Method for manufacturing air filter media, and air filter media

Abstract

The present invention provides a method for manufacturing an air filter material capable of enhancing its antifungal effect, and an air filter material itself. [Solution] A method for manufacturing an air filter media, comprising the steps of applying a first resin layer to a filter media layer and applying a second resin layer to the first resin layer, wherein the second resin layer contains an antifungal agent, and the first resin layer contains less antifungal agent per unit area than the second resin layer, or does not contain an antifungal agent.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing an air filter medium and an air filter medium.

Background Art

[0002] Conventionally, in an air filter medium for capturing dust and the like contained in the air, mold may occur.

[0003] In contrast, for example, according to Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-205211), an air filter medium in which an antibacterial reinforcing material using an antifungal agent or an antibacterial agent is laminated on a polytetrafluoroethylene porous membrane has been proposed.

Disclosure of the Invention

Problems to be Solved by the Invention

[0004] As such an air filter medium to which an antifungal agent is applied, it is desirable to enhance the antifungal effect by the applied antifungal agent.

Means for Solving the Problems

[0005] In order to solve the above problems, as a result of intensive studies by the inventors of the present application, prior to applying a resin layer containing an antifungal agent to a filter medium layer, forming a resin layer on the filter medium layer is significant for exerting the performance of the antifungal agent. Further studies were repeated, and the method for manufacturing an air filter medium and the air filter medium of the present disclosure described below were completed.

[0006] The method for manufacturing an air filter medium according to the first aspect includes a step of applying a first resin layer to a filter medium layer and a step of applying a second resin layer to the first resin layer. The second resin layer contains an antifungal agent. The first resin layer has a lower content of the antifungal agent per unit area than the second resin layer, or the first resin layer does not contain an antifungal agent.

[0007] According to this method for manufacturing air filter media, it is possible to enhance the antifungal effect of antifungal agents in the resulting air filter media.

[0008] The method for manufacturing an air filter material according to the second perspective is the method for manufacturing an air filter material according to the first perspective, wherein the first resin layer does not contain an antifungal agent.

[0009] According to this method for manufacturing air filter media, it is possible to further enhance the antifungal effect of the antifungal agent in the resulting filter media.

[0010] The method for manufacturing air filter media according to the third aspect is the method for manufacturing air filter media according to the first or second aspect, wherein the antifungal agent is a powdered antifungal agent. The filter media layer is composed of fibers. The average particle size of the powdered antifungal agent is smaller than the average fiber size of the fibers.

[0011] This method for manufacturing air filter media makes it easier to suppress the shedding of the applied powdered antifungal agent from the fibers.

[0012] The method for manufacturing the air filter material relating to the fourth viewpoint is the method for manufacturing the air filter material relating to the first viewpoint or the third viewpoint, and the antifungal agent is an inorganic antifungal agent.

[0013] The method for manufacturing an air filter material relating to the fifth aspect is a method for manufacturing an air filter material relating to any of the first or fourth aspects, wherein the first resin layer and the second resin layer are coated by flexographic printing or gravure printing.

[0014] This method for manufacturing air filter media makes it easier to minimize the increase in pressure loss of the air filter media caused by coating.

[0015] The method for manufacturing air filter media according to the sixth perspective is a method for manufacturing air filter media according to any of the first to fifth perspectives, wherein the amount of the first resin layer and the second resin layer applied to the filter media layer is such that the increase in pressure loss of the filter media obtained by applying the first resin layer and the second resin layer to the pressure loss of the filter media obtained by applying the first resin layer and the second resin layer from the pressure loss of the filter media alone before the application of the first resin layer and the second resin layer is 10 Pa or less, or the decrease in collection efficiency of the filter media obtained by applying the first resin layer and the second resin layer to the collection efficiency of the filter media obtained by applying the first resin layer and the second resin layer to the collection efficiency of the filter media alone is 10% or less of the collection efficiency of the filter media alone. Here, the pressure loss is the pressure loss when air is passed through the filter media alone or the air filter media at a flow velocity of 5.3 cm / sec. The collection efficiency is the collection efficiency of polyalphaolefin particles with a particle size of 0.3 μm to the filter media alone or the air filter media.

[0016] This method for manufacturing air filter media makes it possible to obtain antifungal effects while minimizing pressure loss or deterioration in collection efficiency of the resulting air filter media.

[0017] The method for manufacturing an air filter material relating to the seventh aspect is a method for manufacturing an air filter material relating to any of the first or sixth aspects, wherein the average interparticle distance of the antifungal agent in the thickness direction of the second resin layer is 10 μm or less.

[0018] This method of manufacturing air filter media makes it possible to allow mold spores to come into contact with the antifungal agent more easily.

[0019] The method for manufacturing an air filter material relating to the eighth viewpoint is the method for manufacturing an air filter material relating to any of the first viewpoints or the seventh viewpoint, wherein the thickness of the first resin layer is 50% or more and 150% or less of the thickness of the second resin layer.

[0020] This method for manufacturing air filter media makes it possible to reduce the amount of coating required to form the first resin layer, thereby suppressing deterioration of the filter media's performance, while also making it easier to retain the antifungal agent.

[0021] The manufacturing method of the air filter filter medium according to the 9th aspect is the manufacturing method of the air filter filter medium according to any one of the 1st to 8th aspects, and the filter medium layer contains polypropylene fibers.

[0022] This manufacturing method of the air filter filter medium can enhance the mold prevention effect in the air filter filter medium containing polypropylene fibers.

[0023] The air filter filter medium according to the 10th aspect includes a first resin layer, a second resin layer, and a filter medium layer. The first resin layer is located between the second resin layer and the filter medium layer. The second resin layer contains a mold inhibitor. The first resin layer has a lower content of the mold inhibitor per unit area than the second resin layer, or the first resin layer does not contain a mold inhibitor.

[0024] This air filter filter medium can enhance the mold prevention effect by the mold inhibitor.

Brief Description of the Drawings

[0025] [Figure 1] SEM photograph of the filter medium of Example 1. [Figure 2] SEM photograph of the filter medium of Example 2. [Figure 3] SEM photograph of the filter medium of Comparative Example 1. [Figure 4] SEM photograph of the filter medium of Comparative Example 2. [Figure 5] SEM photograph of the filter medium of Example 3. [Figure 6] SEM photograph of the base material as the filter medium layer before applying the paint.

Modes for Carrying Out the Invention

[0026] Hereinafter, the manufacturing method of the air filter filter medium and the air filter filter medium will be described by taking embodiments as examples.

[0027] (1) Manufacturing method of air filter filter medium and air filter filter medium A method for manufacturing an air filter media comprises the steps of applying a first resin layer to a filter media layer and applying a second resin layer to the first resin layer, wherein the second resin layer contains an antifungal agent, and the first resin layer contains less antifungal agent per unit area than the second resin layer, or the first resin layer does not contain an antifungal agent.

[0028] (1-1) Filter medium layer The filter layer is not particularly limited and may be, for example, a porous membrane or a nonwoven fabric, and is preferably composed of fibers.

[0029] Examples of fibers include polypropylene (PP), polyethylene terephthalate (PET), polyethylene (PE), polyamide (PA), and glass fiber, with polypropylene being preferred from the viewpoint of easily retaining antifungal agents.

[0030] The average fiber diameter may be, for example, 1 μm or more and 30 μm or less, and preferably 3 μm or more and 10 μm or less.

[0031] The average fiber diameter is determined as follows: First, the surface of the test sample is imaged with a scanning electron microscope (SEM) at 1000 to 5000x magnification. Two orthogonal lines are drawn on one of the captured images, and the thickness of the fiber image where it intersects these lines is obtained as the fiber diameter. Here, the number of fibers measured should be 200 or more. The obtained fiber diameters are plotted on a log-normal scale with fiber diameter on the x-axis and cumulative frequency on the y-axis, and the value at which the cumulative frequency reaches 50% is taken as the average fiber diameter. The geometric standard deviation representing the distribution of fiber diameters is obtained by reading the fiber diameters at 50% and 84% cumulative frequency from the results of the log-normal plot described above and calculating it using the following formula. It is preferable that this geometric standard deviation be 2.0 or less. Geometric standard deviation [-] = Cumulative frequency 84% fiber diameter / Cumulative frequency 50% fiber diameter

[0032] Furthermore, the filter media layer preferably has a pressure loss of 10 Pa or more, and more preferably 30 Pa or more, when air is passed through it at a flow velocity of 5.3 cm / second. While there is no particular upper limit to the pressure loss of the filter media layer, it is preferably 200 Pa, and more preferably 50 Pa.

[0033] Furthermore, the filter media layer preferably has a collection efficiency of 30% or more, and more preferably 35% or more, for polyalphaolefin particles with a particle size of 0.3 μm. The upper limit of the collection efficiency of the filter media layer is not particularly limited, but preferably, for example, 60% or more, and more preferably 50%.

[0034] The filter media layer may be an charged filter media layer or an uncharged filter media layer, but from the viewpoint of suppressing changes in the charged state by applying the first resin layer and the second resin layer, it is preferable that it be an uncharged filter media layer.

[0035] (1-2) First resin layer and its application The first resin layer is the layer that is in direct contact with the filter media layer.

[0036] By applying the first resin layer to the filter material layer prior to coating the second resin layer containing the antifungal agent, it becomes easier to improve the uniformity of the second resin layer's application (especially the uniformity of the antifungal agent contained in the second resin layer), and also improve the adhesion of the antifungal agent.

[0037] The first resin layer is preferably a layer applied by flexographic printing or gravure printing, from the viewpoint of minimizing the deterioration of pressure loss or collection efficiency of the resulting air filter media.

[0038] The resin constituting the first resin layer is preferably a resin that functions as a binder resin, and is preferably an acrylic resin or an olefin resin.

[0039] Examples of acrylic resins include polymers or copolymers of (meth)acrylates such as polyacrylic acid esters, polyethyl methacrylate, polybutyl methacrylate, butyl methacrylate / methyl methacrylate copolymers, butyl methacrylate / ethyl methacrylate copolymers, 2-ethylhexyl methacrylate / ethyl methacrylate copolymers, and lauryl methacrylate / ethyl methacrylate copolymers.

[0040] Examples of olefin resins include polyethylene and polypropylene, and among these, aqueous dispersions of polyolefins having carboxyl groups are preferred.

[0041] Furthermore, the first paint, which is a paint containing the first resin used to form the first resin layer, is preferably an aqueous emulsion that does not contain organic solvents.

[0042] Examples of methods for applying the first coating include plated printing such as gravure printing, flexographic printing, screen printing, and offset printing, as well as plateless printing such as inkjet printing and various transfer printing methods. However, from the viewpoint of minimizing the increase in pressure loss in the filter layer and ensuring that the coating spreads uniformly on the surface of the filter layer without clumping (reduced uniformity due to the formation of coating clumps), gravure printing or flexographic printing is preferred.

[0043] Furthermore, the first resin layer may contain an antifungal agent as described later. In this case, the amount of antifungal agent per unit area in the first resin layer is less than the amount of antifungal agent per unit area in the second resin layer, preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 5% by mass or less. Most preferably, the first resin layer does not contain an antifungal agent. By keeping the amount of antifungal agent in the first resin layer low, it is possible to improve the adhesion of the antifungal agent in the second resin layer and to suppress the shedding of the antifungal agent from the second resin layer.

[0044] Furthermore, the thickness of the first resin layer is preferably 50% to 150% of the thickness of the second resin layer, from the viewpoint of suppressing deterioration of the filter media layer's performance due to an excessively large thickness of the first resin layer, while also effectively suppressing the shedding of the antifungal agent contained in the second resin layer.

[0045] (1-3) Second resin layer and its application The second resin layer is a layer that is in direct contact with the first resin layer.

[0046] The second resin constituting the second resin layer may be the same type as the first resin constituting the first resin layer or a different type, but it is preferable that it be the same type from the viewpoint of improving affinity.

[0047] The resin constituting the second resin layer is preferably a resin that functions as a binder resin, and is preferably an acrylic resin or an olefin resin.

[0048] Examples of acrylic resins include polymers or copolymers of (meth)acrylates such as polyethyl methacrylate, polybutyl methacrylate, butyl methacrylate / methyl methacrylate copolymer, butyl methacrylate / ethyl methacrylate copolymer, 2-ethylhexyl methacrylate / ethyl methacrylate copolymer, and lauryl methacrylate / ethyl methacrylate copolymer.

[0049] Furthermore, the second coating used to form the second resin layer is preferably an aqueous emulsion that does not contain organic solvents.

[0050] The method of applying the second coating may be the same as or different from the method of applying the first coating. Examples include plated printing such as gravure printing, flexographic printing, silkscreen printing, and offset printing, as well as plateless printing such as inkjet printing and various transfer printing methods. Among these, gravure printing or flexographic printing is preferred for the application method of the second coating, as it allows the second coating, which is applied with an antifungal agent mixed in, to be applied in a manner that minimizes the increase in pressure loss in the filter material layer, allows the antifungal agent to spread uniformly without clumping on the filter material layer on which the first resin layer is formed, and suppresses the shedding of the antifungal agent. It should be noted that the antifungal agent can function if it is present on the surface of the air filter material, but it is difficult for it to function if it is located inside the air filter material in the thickness direction, resulting in wasted paint. Therefore, gravure printing or flexographic printing, which allows application to the center of the surface, is preferred over application by immersion in a resin coating containing an antifungal agent.

[0051] Furthermore, it is preferable to apply the second resin layer after the first resin layer has been applied, for example, after a predetermined time such as 5 minutes or 10 minutes or more has passed, and the second resin layer has dried.

[0052] The second resin layer contains an antifungal agent. Applying the second resin layer containing the antifungal agent to the filter media layer coated with the first resin layer suppresses the shedding of the antifungal agent in the resulting air filter media more effectively than directly applying the second resin layer containing the antifungal agent to the filter media layer.

[0053] (1-4) Antifungal agents As a fungicide, it is preferable that it has a particulate form. The fungicide in particulate form may also be in powder form.

[0054] Examples of antifungal agents include organic antifungal agents and inorganic antifungal agents.

[0055] Examples of known organic fungicides include organic nitrogen compounds and sulfur compounds.

[0056] Examples of inorganic antifungal agents include metal nanoparticles such as silver, copper, and zinc; metal oxides such as silver oxide, zinc oxide, nickel oxide, titanium oxide, iron oxide, and copper oxide; and silicon nitride. However, from the viewpoint of easily suppressing leaching, it is preferable to use metal oxides, and among metal oxides, ferrite containing iron oxide as the main component is preferred. As for ferrite, for example, the ferrite described in Japanese Patent Application Publication No. 2023-163851 can be suitably used.

[0057] When the antifungal agent is in the form of a powder or other particulate matter, and the filter layer is composed of fibers, the average particle size of the antifungal agent is preferably smaller than the average fiber diameter of the fibers in the filter layer, more preferably half or less of the average fiber diameter of the fibers in the filter layer, and even more preferably 1 / 10 or less of the average fiber diameter of the fibers in the filter layer. The lower limit of the average particle size of the antifungal agent may be, for example, half or more of the film thickness of the portion of the second resin layer excluding the antifungal agent, and preferably equal to or greater than the film thickness of the portion of the second resin layer excluding the antifungal agent.

[0058] When the antifungal agent is in particulate form, the average particle size is preferably 0.1 μm to 5.0 μm, and more preferably 0.15 μm to 3.0 μm, from the viewpoint of preventing it from becoming embedded in the resin of the second resin layer.

[0059] The weight ratio of the antifungal agent contained in the second resin to 100 parts by weight of the second resin layer is preferably 80 parts by weight or more, more preferably 90 parts by weight or more, and even more preferably 100 parts by weight or more, from the viewpoint of ensuring that the antifungal agent not covered by the second resin is secured and that it is easy to exert its antifungal function.

[0060] Furthermore, the weight ratio of the antifungal agent contained in the second resin to 100 parts by weight of the second resin layer is preferably 145 parts by weight or less, and preferably 135 parts by weight or less, from the viewpoint of suppressing the detachment of the antifungal agent due to the antifungal agent becoming less retained by the second resin.

[0061] Furthermore, from the viewpoint of making the antifungal agent contained in the second resin layer more easily accessible to mold spores, it is preferable that the average interparticle distance of the antifungal agent in the thickness direction of the second resin layer be 10 μm or less. The average interparticle distance may be, for example, the average value obtained by measuring the interparticle distance between the nearest antifungal agent particle and a randomly extracted antifungal agent particle in an SEM image, and repeating this 10 or more times. In this measurement of the average interparticle distance, if multiple antifungal agents are present in a cluster, they can be considered as a single particle.

[0062] Furthermore, from the viewpoint of making it easier for the antifungal agent contained in the second resin layer to come into contact with mold spores, it is preferable that the area ratio of the antifungal agent to the total area of ​​the second resin layer, viewed in the thickness direction, be between 4% and 20%. This area ratio can be calculated by focusing on a predetermined area in an image such as an SEM photograph.

[0063] Furthermore, it is preferable that the antifungal agent contained in the second resin layer remains dispersed with a small particle size, without becoming larger than 20 μm due to aggregation when the second resin layer is formed by coating. For example, if the average particle size of the antifungal agent is 0.2 μm, it is preferable that particles with a particle size 100 times or less of that average are dispersed, and it is preferable that particles with a particle size 10 times or less of that average are dispersed.

[0064] (1-5) Air filter media The air filter media preferably has a pressure loss of 10 Pa or more, and more preferably 30 Pa or more, when air is passed through it at a flow velocity of 5.3 cm / second. While there is no particular upper limit to the pressure loss of the air filter media, it is preferably 200 Pa, and more preferably 50 Pa.

[0065] Furthermore, the air filter media preferably has a collection efficiency of 30% or more, and more preferably 35% or more, for polyalphaolefin particles with a particle size of 0.3 μm. The upper limit of the collection efficiency of the air filter media is not particularly limited, but preferably, for example, 60% or more, and more preferably 50%.

[0066] The amount of the first resin layer and the second resin layer applied to the filter media layer is preferably such that, from the viewpoint of imparting antifungal performance while suppressing deterioration of the performance of the filter media layer, the increase in the pressure loss of the air filter media obtained by applying the first resin layer and the second resin layer to the filter media layer is 10 Pa or less, more preferably 7 Pa or less, and even more preferably 4 Pa ​​or less.

[0067] Furthermore, the amount of the first and second resin layers applied to the filter media layer is preferably such that, from the viewpoint of imparting antifungal performance while suppressing deterioration of the performance of the filter media layer, the decrease in the collection efficiency of the air filter media obtained by applying the first and second resin layers to the collection efficiency of the filter media layer alone is within 10%, more preferably within 6%, and even more preferably within 2%. However, as long as the increase in pressure loss is kept to a minimum, it is acceptable for the collection efficiency of the filter media layer to improve due to the application.

[0068] Furthermore, the amount of the first resin layer and the second resin layer applied to the filter material layer is preferably such that, when the filter material layer is composed of fibers, the average fiber diameter after application is three times or less the average fiber diameter before application, and more preferably two times or less.

[0069] Furthermore, as an air filter media, a support layer may be provided on the side of the filter media layer opposite to the side to which the first resin layer and the second resin layer are coated. Examples of support layers include nonwoven fabric, woven fabric, metal mesh, and resin net. Among these, nonwoven fabric with heat-sealing properties is preferred in terms of strength, flexibility, and workability. The material of the nonwoven fabric is not particularly limited, and polyolefins such as polyethylene and polypropylene, polyamides, polyesters such as polyethylene terephthalate, aromatic polyamides, or composites thereof can be used.

[0070] Furthermore, air filter media are most effective when used in environments where mold growth is a particular concern. For example, air filter media are preferably used in environments with a relative humidity of 60% or higher, more preferably in environments with a temperature of 20 degrees Celsius or higher and a relative humidity of 60% or higher, and even more preferably in environments with a temperature of 25 degrees Celsius or higher and a relative humidity of 70% or higher.

[0071] The air filter material may be an air filter for which the fluid to be treated is a gas, or a filter for which the fluid to be treated is a liquid. [Examples]

[0072] The contents of this disclosure will be specifically explained below with reference to examples and comparative examples.

[0073] Examples and comparative examples were prepared by applying at least one of the first resin layer and the second resin layer to a substrate prepared as a filter media layer.

[0074] The filter material used as the substrate for the filter layer was a non-static filter made of polypropylene fibers. The filter layer had a pressure drop of 36 Pa and a collection efficiency of 39.7%. The average fiber diameter of the fibers in the filter layer was 5 μm.

[0075] (Example 1) In Example 1, a first coating made of a first resin was applied to a substrate to be used as a filter material layer to form a first resin layer, and after drying, a second coating was applied to form a second resin layer, thereby obtaining the filter material of Example 1.

[0076] Both the first and second resins used were olefin-based resins, specifically polyolefin-based aqueous dispersions containing carboxyl groups (Zychsen L, manufactured by Sumitomo Seika Co., Ltd.).

[0077] The second coating contained ferrite particles, which are a powdered antifungal agent, with an average particle size of 0.2 μm. The mixing ratio (mass ratio) of the second resin to the antifungal agent in the second coating was 10:10. The amount of the second coating applied was such that the area ratio of the antifungal agent (planar view) to the total area (planar view) of the filter material obtained after coating was 4.9%.

[0078] The application weights of the first and second coatings were the same, and both were applied using flexographic printing techniques.

[0079] (Example 2) In Example 2, the filter material for Example 2 was obtained in the same manner as in Example 1, except that a ferrite particle powder, which is a fungicide, with an average particle size of 1.0 μm was used, and a second coating was applied in an amount such that the area ratio of the fungicide was 4.0%.

[0080] (Comparative Example 1) Comparative Example 1 was a filter material in which only one layer was formed by coating. The first resin used in the coating that formed the first resin layer of Comparative Example 1 (the first coating of Comparative Example 1) was an olefin-based resin, the same as in Example 1. In addition, the first coating of Comparative Example 1 was formulated with the same antifungal agent as in Example 1. The mixing ratio (mass ratio) of the first resin to the antifungal agent in the first coating of Comparative Example 1 was 10:10. The coating method was also the same as in Example 1, using flexographic printing. The amount of the first coating of Comparative Example 1 applied was such that the area ratio of the antifungal agent on the filter material was 4.7%.

[0081] (Comparative Example 2) Comparative Example 2 used a filter material in which an antifungal agent was further incorporated into the first resin layer of Example 1. The antifungal agent contained in the first resin layer of Comparative Example 2 was the same as that contained in the second resin layer of Example 1. The coating weights of the paint that formed the first resin layer of Comparative Example 2 (first paint of Comparative Example 2) and the paint that formed the second resin layer of Comparative Example 2 (second paint of Comparative Example 2) were the same, and both were applied using flexographic printing. The mixing ratio (mass ratio) of the first resin to the antifungal agent in the first paint of Comparative Example 2 was 10:10, and the mixing ratio (mass ratio) of the second resin to the antifungal agent in the second paint of Comparative Example 2 was also 10:10. In Comparative Example 2, the coating amounts of the first paint and the second paint were the same, resulting in a surface area ratio of 5.2% for the antifungal agent on the filter material.

[0082] (Example 3) Example 3 was the same as Example 1, except that gravure printing was used instead of flexographic printing as the coating method for the first and second coatings, and the amount of the second coating applied was such that the area ratio of the antifungal agent was 4.0%.

[0083] (Comparative Example 3) Comparative Example 3 was a filter material in which only one layer was formed by coating. Unlike Example 1, an acrylic resin was used as the first resin in the coating that formed the first resin layer of Comparative Example 3 (the first coating of Comparative Example 3). In addition, the first coating of Comparative Example 3 contained the same antifungal agent as in Example 1. The mixing ratio (mass ratio) of the first resin to the antifungal agent in the first coating of Comparative Example 3 was 10:10. The coating method involved immersing the substrate as the filter material layer in the first coating. The amount of first coating applied to Comparative Example 3 was such that the area ratio of the antifungal agent on the filter material was 20.0%.

[0084] The physical properties measured for each example, comparative example, and substrate used as the filter layer are as follows.

[0085] (Pressure loss) A sample of the filter media was placed in a 100 mm diameter filter holder, the inlet side was pressurized with a compressor, and the airflow rate was adjusted to 5.3 cm / second using a flow meter. The pressure loss at this time was then measured with a manometer.

[0086] The pressure loss was measured for the substrate, which is the filter media layer, and for the filter media of each example and comparative example obtained by applying each coating.

[0087] (Collection efficiency of polyalphaolefin (PAO) particles with a particle size of 0.3 μm) The collection efficiency of polyalphaolefin (PAO) particles (liquid particles) was evaluated by a pressure drop increase test. Air containing PAO particles was filtered over an effective filtration area of ​​50 cm². 2 When a continuous airflow of 5.3 cm / sec was passed through the sample filter media, the collection efficiency was calculated from the upstream concentration C1 and the downstream concentration C2 using the formula (1-C2) / C1×100. The PAO particles used were those generated with a Ruskin nozzle (median particle size 0.3 μm), and the concentration of PAO particles was approximately 1 million to 6 million particles / cm³. 3 That's what I decided.

[0088] The collection efficiency was measured for the substrate, which is the filter media layer, and for the filter media of each example and comparative example obtained by applying each coating.

[0089] (Fungal agent powder shedding test) For each example and comparative example, a white piece of paper was placed in contact with the surface and lightly rubbed. If color transfer to the white paper was observed, it was evaluated as having powder shedding; if no color transfer was observed, it was evaluated as not having powder shedding. In this example, since the antifungal agent used was brown, if powder shedding was evaluated as having occurred, it was considered that the antifungal agent had detached from the second resin layer. The evaluation was performed twice, at different time intervals: the first time after 2 days and the second time after 2 weeks.

[0090] (JIS Z2911 mold resistance test (textile products, wet method)) The above-mentioned Example 1 and Comparative Example 1 were subjected to tests in accordance with the mold resistance test of JIS Z2911.

[0091] The sample was cut to a predetermined size and placed on an agar medium containing ammonium nitrate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, potassium chloride, iron(II) sulfate heptahydrate, agar, and purified water. A mixed spore solution containing spores of Aspergillus niger, Penicillium citrinum, Ketomium globosum, and Myrotesium vercaria was sprayed onto the sample, and the growth of mold on the sample surface was observed under a temperature of 26±2°C.

[0092] In the mold resistance test, the evaluation of mold growth was as follows: a rating of 0 was given for samples where no mycelial growth was observed with the naked eye; a rating of 1 was given for samples where the area where mycelial growth was observed did not exceed 1 / 3 of the total area; and a rating of 2 was given for samples where the area where mycelial growth was observed exceeded 1 / 3 of the total area.

[0093] (SEM image) SEM images were taken for each example and comparative example.

[0094] For each SEM image, Figure 1 shows the filter material of Example 1, Figure 2 shows the filter material of Example 2, Figure 3 shows the filter material of Comparative Example 1, Figure 4 shows the filter material of Comparative Example 2, Figure 5 shows the filter material of Example 3, and Figure 6 shows the substrate, which is the filter material layer before paint application. Here, Figures 1 to 6 are shown at a magnification of 1000x.

[0095] The physical properties of the filter media for each example and comparative example, and the physical properties of each porous membrane are shown in Table 1 below. [Table 1] [Table 2]

[0096] In each example and comparative example, the increase in pressure loss due to the application of paint to the substrate as the filter layer was kept below 10 Pa in all cases, and the change in collection efficiency was kept within 10% in all cases.

[0097] Examples 1, 2, and 3 achieved a score of 0 (no mycelial growth was observed in the inoculated area of ​​the sample or test piece) in the JIS Z2911 mold resistance test. Comparative Examples 1 and 2 achieved a score of 1 (the area where mycelial growth was observed did not exceed 1 / 3 of the total area). In Comparative Examples 1 and 2, it is thought that mold growth was more likely due to areas where the antifungal agent was not uniformly dispersed, resulting in areas with little or no antifungal agent.

[0098] In Examples 1, 2, and 3, no color transfer (inhibition of fungicide shedding) was achieved in the powder shedding tests conducted 2 days and 2 weeks after the filter media was prepared. In Comparative Examples 1 and 2, no color transfer (inhibition of fungicide shedding) was achieved in the powder shedding test conducted 2 weeks after the filter media was prepared, but color transfer (shedding of fungicide) was observed in the powder shedding test conducted 2 days after the filter media was prepared.

[0099] In addition, in Comparative Example 3, too much paint was applied to the substrate as a filter layer, causing clogging and resulting in cracking on the surface.

[0100] While embodiments of this disclosure have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of this disclosure as described in the claims. [Prior art documents] [Patent Documents]

[0101] [Patent Document 1] Japanese Patent Publication No. 2003-205211

Claims

1. A step of applying a first resin layer to the filter media layer, A step of applying a second resin layer to the first resin layer, Equipped with, The second resin layer contains an antifungal agent. The first resin layer has a lower content of the antifungal agent per unit area than the second resin layer, or does not contain the antifungal agent at all. A method for manufacturing air filter media.

2. The first resin layer does not contain the antifungal agent. A method for manufacturing an air filter material according to claim 1.

3. The aforementioned antifungal agent is a powdered antifungal agent. The aforementioned filter material layer is composed of fibers, The average particle size of the powdered antifungal agent is smaller than the average fiber diameter of the fibers. A method for manufacturing an air filter material according to claim 1 or 2.

4. The aforementioned antifungal agent is an inorganic antifungal agent. A method for manufacturing an air filter material according to claim 1 or 2.

5. The first resin layer and the second resin layer are coated by flexographic printing or gravure printing. A method for manufacturing an air filter material according to claim 1 or 2.

6. The amount of the first resin layer and the second resin layer applied to the filter material layer is: Whether the amount of resin applied is such that the increase in pressure loss of the filter material obtained by applying the first resin layer and the second resin layer to the filter material layer is within 10 Pa, compared to the pressure loss of the filter material layer alone before the application of the first resin layer and the second resin layer, Whether the amount of resin applied is such that the decrease in the collection efficiency of the filter material obtained by applying the first resin layer and the second resin layer to the collection efficiency of the filter material obtained by applying the first resin layer and the second resin layer to the filter material layer is within 10% of the collection efficiency of the filter material layer alone, It is at least one of the following: The aforementioned pressure loss is the pressure loss when air is passed through at a flow velocity of 5.3 cm / second. The aforementioned collection efficiency is the collection efficiency for polyalphaolefin particles with a particle size of 0.3 μm. A method for manufacturing an air filter material according to claim 1 or 2.

7. In the thickness direction of the second resin layer, the average interparticle distance of the antifungal agent is 10 μm or less. A method for manufacturing an air filter material according to claim 1 or 2.

8. The thickness of the first resin layer is 50% or more and 150% or less of the thickness of the second resin layer. A method for manufacturing an air filter material according to claim 1 or 2.

9. The filter material layer includes polypropylene fibers, A method for manufacturing an air filter material according to claim 1 or 2.

10. It comprises a first resin layer, a second resin layer, and a filter material layer. The first resin layer is located between the second resin layer and the filter material layer. The second resin layer contains an antifungal agent. The first resin layer has a lower content of the antifungal agent per unit area than the second resin layer, or does not contain the antifungal agent at all. Air filter media.

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