High-performance filter media

Abstract

To provide a high-functionality filter medium that efficiently expresses various functions such as antibacterial, antiviral, antifungal, and anti-allergen properties.SOLUTION: A filter medium according to the present invention is a high-functionality filter medium for air filters, including at least a functional layer and a liquid repellent layer, where the functional layer is situated on the upstream side of air flow and the liquid repellent layer is situated on the downstream side of air flow, and the functional layer includes one or more functional agents selected from antibacterial, antiviral, antifungal and anti-allergen agents.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a high-performance filter material suitable for use in air filter applications. [Background technology]

[0002] In recent years, with air pollution such as PM2.5 becoming a problem, the demand for filter media for air purifiers, automotive cabin filters, and masks has increased due to the need to live in a cleaner air environment. Common to all of these applications is the technology of removing fine dust from the air using filter media made of nonwoven fabrics, etc. These filter media require both high collection efficiency and high breathability.

[0003] Furthermore, the substances captured by the filter media of the air purifier filters and automobile cabin filters mentioned above include allergens derived from dust mites and pollen, as well as mold spores, fungi, viruses, etc. Since these substances can cause disease, it is desirable that they be inactivated on the filter media where they are captured.

[0004] For example, Patent Document 1 discloses a filter material in which an antibacterial agent is added to a coarse dust collection sheet and an adhesive material, and an electret fine dust collection sheet is laminated on top of it. However, the above filter material was still insufficient in capturing allergens, mold spores, fungi, viruses, etc. from the air. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-561 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention aims to solve these conventional problems and to provide a high-performance filter material that efficiently exhibits various functions such as antibacterial, antiviral, antifungal, and anti-allergen properties. [Means for solving the problem]

[0007] To solve the above problems, the high-performance filter material of the present invention has the following features. (1) A high-performance filter material for an air filter comprising at least a functional layer and a liquid-repellent layer, wherein the functional layer is arranged on the upstream side of the airflow and the liquid-repellent layer is arranged on the downstream side of the airflow, and the functional layer comprises one or more functional agents selected from antibacterial agents, antiviral agents, antifungal agents and antiallergen agents. (2) The high-performance filter material according to (1) above, wherein the liquid-repellent layer contains a fluororesin. (3) The high-performance filter material according to (1) or (2) above, wherein the functional agent has high water solubility. (4) The high-performance filter material according to any one of (1) to (3) above, wherein the liquid-repellent layer is an electrostatically charged nonwoven fabric. (5) A high-performance filter material according to any one of (1) to (4) above, wherein the functional layer and the liquid-repellent layer are in contact. (6) A high-performance filter material according to any one of (1) to (5) above, wherein the water absorption height of the functional layer in the Baylec water absorption test is greater than the water absorption height of the liquid-repellent layer in the Baylec water absorption test. [Effects of the Invention]

[0008] The high-performance filter material of the present invention has a liquid-repellent layer on the downstream side, which makes it difficult for moisture containing bacteria, viruses, mold, and allergens to penetrate the liquid-repellent layer and allows it to remain in the functional layer on the upstream side. This increases the contact rate with functional agents, and allows for the efficient expression of functions such as antibacterial, antiviral, antifungal, and anti-allergen properties. [Modes for carrying out the invention]

[0009] The high-performance filter material of the present invention will be described in detail below.

[0010] [Functional Layer] The functional layer in the present invention contains one or more functional agents selected from antibacterial agents, antiviral agents, antifungal agents, and anti-allergen agents.

[0011] Antibacterial property refers to the function of preventing and suppressing the growth of bacteria by reducing or killing the number of bacteria. When the fiber layer constituting the functional layer has antibacterial property, it means that the processing for suppressing the growth of bacteria on the fiber layer has been carried out. The imparting of antibacterial property is obtained by imparting a functional agent having an antibacterial function (hereinafter referred to as an antibacterial agent) to the fiber layer.

[0012] The antibacterial agent used in the present invention is not particularly limited. As inorganic antibacterial agents, metal nanoparticles such as silver, copper, and zinc, zeolite, silica gel, glass, calcium phosphate, zirconium phosphate, calcium silicate, magnesium metasilicate aluminate, potassium titanate, zinc oxide, and carriers obtained by imparting metals such as silver, copper, and zinc to carriers, and metal oxides such as zinc oxide, copper oxide, and titanium dioxide can be preferably used. As organic antibacterial agents, thiazoline-based such as 2-n-octyl-4-isothiazolin-3-one and 1,2-benzisothiazolin-3-one, carboxylic acid-based such as sorbic acid, carbamate-based such as 3-iodo-2-propynyl butylcarbamate, quaternary ammonium salt-based such as benzalkonium chloride, didecyldimethylammonium chloride, dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, dimethyltetradecyl[3-(trimethoxysilyl)propyl]ammonium chloride, hexadecylpyridinium chloride, phenol-based such as 3-methyl-4-isopropylphenol, 4-chloro-3,5-dimethylphenol, 3-methyl-4-chlorophenol, and polyphenols derived from natural products such as catechins and tannins can be preferably used. In particular, since bacteria, viruses, molds, and allergens are often present in water, it is more preferable to use an antibacterial agent that is easily eluted in water and has high water solubility. Catechins and tannins are more preferable from the viewpoint of excellent antibacterial property. An antibacterial agent having high water solubility means that the solubility in water at 25°C is 10 g / L or more. The antibacterial agent may be used alone or in combination of a plurality of antibacterial agents.

[0013] The antibacterial property can be measured by the antibacterial test of textile products using the halo method of JIS L 1902 (2015). It is preferably that the antibacterial activity value is 2.2 or more against Staphylococcus aureus and Klebsiella pneumoniae. More preferably, it is 2.5 or more, and even more preferably 3.0 or more.

[0014] Antiviral property refers to the function of denaturing the proteins on the virus surface or damaging the structure, thereby eliminating the compatibility with the receptors of host cells and reducing the activity. It includes the denaturation of the envelope in enveloped viruses. That the fiber layer constituting the functional layer has antiviral property means that processing for reducing the activity of the virus is performed on the fiber layer. The impartation of antiviral property is obtained by imparting a functional agent having an antiviral function (hereinafter referred to as an antiviral agent) to the fiber layer.

[0015] The antiviral agents used in the present invention are not particularly limited, but suitable inorganic antiviral agents include metal nanoparticles such as silver, copper, and zinc; metal oxides such as copper oxide, zinc oxide, and titanium oxide; carriers such as zeolites, silica gel, glass, calcium phosphate, zirconium phosphate, calcium silicate, magnesium aluminometasilicate, potassium titanate, and zinc oxide, to which metals such as silver, copper, and zinc are attached. Suitable organic antiviral agents include quaternary ammonium salts such as organic benzalkonium chloride, didecyldimethylammonium chloride, dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, dimethyltetradecyl[3-(trimethoxysilyl)propyl]ammonium chloride, and hexadecylpyridinium chloride; carbamates such as 3-iodo-2-propynylbutylcarbamate; and polyphenols derived from natural products such as catechins and tannins. As mentioned above, since bacteria, viruses, molds, and allergens are often present in water, it is preferable to use an antiviral agent that is highly water-soluble and easily dissolves in water, and catechins and tannins are more preferable due to their excellent antiviral properties. An antiviral agent with high water solubility is defined as one whose solubility in water at 25°C is 10 g / L or more. Antiviral agents may be used alone or in combination of multiple antiviral agents.

[0016] Antiviral activity can be measured according to the JIS L 1922 (2016) plaque assay method for testing the antiviral activity of textile products. While the target virus species is not limited, for example, it is preferable that the antiviral activity value against influenza virus (H1N1) be 2.0 or higher. More preferably, it is 2.5 or higher, and even more preferably 3.0 or higher.

[0017] Antifungal properties refer to the ability to penetrate the inside of mold cells, inhibit the functions necessary for mold growth, and suppress mold reproduction. For a functional layer to have antifungal properties, it means that the fiber layer has been processed to suppress mold growth. Antifungal properties are obtained by applying an antifungal agent (hereinafter referred to as an antifungal agent) to the fiber layer.

[0018] The antifungal agents used in the present invention are not particularly limited, but include benzimidazole-based agents such as 2-(4-thiazolyl)-benzimidazole (thiabendazole) and methyl-2-benzimidazole carbamate (carbendazim), and organic iodide-based agents such as bromo 2,3-diiodo 2-propenylethylcarbonate, 4-chlorphenyl-3'-iodopropagyl pormal, diiodomethyl paratolylsulfone, and 2,3,3-triiodoaryl alcohol. Guanidine-based agents such as dodecylguanidine hydrochloride, polyhexamethylene biguanidine hydrochloride, and chlorhexidine gluconate; sulfamide-based agents such as N-dichlorofluoromethylthio-N',N'-dimethyl-N-phenylsulfamide (diclofluanide) and N-dichlorofluoromethylthio-N',N'-dimethyl-Np-tolylsulfamide (trifluanide); 2-bromo-2-nitropropane-1,3-diol; and orthophenylphenol can be suitably used. As mentioned above, since bacteria, viruses, molds, and allergens are often present in water, it is more preferable to use an antifungal agent that is easily eluted in water and has high water solubility, and polyhexamethylene biguanidine hydrochloride and chlorhexidine gluconate are more preferred in terms of their excellent antifungal properties. An antifungal agent with high water solubility refers to one whose solubility in water at 25°C is 10 g / L or more. Antifungal agents may be used alone, or multiple antiviral agents may be used in combination. In addition, some of the antibacterial and antiviral agents mentioned above also have antifungal properties, and these may be used as appropriate.

[0019] The antifungal properties can be measured according to the mold resistance test method of JIS Z 2911 (2018). The types of molds are not limited, but for example, for Aspergillus niger, Penicillium, Citrinum, Cetomium, Globosum, Myrotesium, and Vercaria, a measurement value of 1 (the area where mycelial growth is observed in the inoculated part of the sample or test piece does not exceed 1 / 3 of the total area) is preferable, and a measurement value of 0 (no mycelial growth is observed in the inoculated part of the sample or test piece) is more preferable.

[0020] Antiallergenic properties refer to the ability to inactivate and neutralize allergens, which are substances that cause allergic symptoms in humans, through methods such as adsorption, coating, or denaturation. Allergens include animal and plant proteins such as the fur and epithelium of dogs, cats, and birds, pollen from cedar, cypress, and ragweed, mold, mites, cockroaches themselves, or their excrement, and are substances that trigger allergic reactions through skin or mucous membrane contact.

[0021] The anti-allergen agents used in the present invention are not particularly limited, but inorganic anti-allergen agents such as polyphenols derived from natural extracts such as tannic acid and catechins, alkaline earth metal salts such as calcium salts and strontium salts, zirconium salts such as zirconyl chloride, zirconium hydroxide, and zirconium carbonate, and aluminum salts such as alum and aluminum sulfate can be suitably used. As mentioned above, since bacteria, viruses, molds, and allergens are often present in water, it is more preferable to use an anti-allergen agent with high water solubility that easily dissolves in water, and catechins are more preferable in terms of their excellent anti-allergen properties. An anti-allergen agent with high water solubility refers to one whose solubility in water at 25°C is 10 g / L or more. The anti-allergen agent may be used alone, or multiple anti-allergen agents may be used in combination. In addition, some of the above-mentioned antibacterial agents and antiviral agents also contain anti-allergen properties, and these can also be used as appropriate.

[0022] The anti-allergenicity is measured by contacting a nonwoven fabric with the undiluted solution containing the antigen, allowing it to stand, and calculating the degree of decrease in the number of antigens in the recovered solution. Specifically, it is calculated using the following formula. Allergen reduction rate (%) = Number of antigens in the recovered solution / Number of antigens in the original solution × 100 Enzyme-linked immunosorbent assay (ELISA) is suitably used to measure the number of antigens in a solution. ELISA utilizes the antigen-antibody reaction, which is the reaction of an antibody that specifically binds to the target allergen. Specifically, it involves labeling an antibody that binds to the allergen with an enzyme, reacting it with a substrate after binding to the allergen to cause the substrate to develop color, and quantifying the allergen concentration in the sample using a calibration curve calculated based on the color development (absorbance) of a standard allergen of known concentration. Among ELISA methods, the sandwich ELISA method is particularly suitable, in which two antibodies are used against the antigen. The first antibody captures the allergen, impurities other than the captured allergen are removed by washing, and then the second antibody is used for detection. This method offers high detection specificity and high reproducibility, and the process from sample preparation to measurement can be carried out in a simple manner.

[0023] For example, it is preferable that the allergen reduction rate for cedar pollen allergens be 90% or higher. More preferably, it is 95% or higher, and even more preferably 98% or higher.

[0024] The functional agents mentioned above, such as antibacterial agents, antiviral agents, antifungal agents, and antiallergen agents, may be used individually or in combination of two or more. However, caution is necessary as certain combinations may impair the function of each functional agent or reduce the physical properties of the functional layer.

[0025] The fibers constituting the functional layer are not particularly limited. For example, synthetic fibers such as polypropylene, polyester, polylactic acid, polyethylene, fluororesin, vinylon, nylon, and rayon can be used, and they can be widely used in woven fabrics, knitted fabrics, non-woven fabrics, etc. In terms of productivity, non-woven fabrics are preferred. The manufacturing method of the non-woven fabric is not particularly limited, and examples include the spunbond method, thermal bonding method, chemical bonding method, needle punching method, hydroentangling method, airlaid method, wet papermaking method, etc.

[0026] The thickness of the functional layer is preferably 0.1 mm or more and 1.0 mm or less. By setting the thickness to 1.0 mm or less, when using the filter medium in a pleated shape, the air permeability resistance derived from the structure can be sufficiently reduced. More preferably, it is 0.5 mm or less. By setting the thickness to 0.1 mm or more, sufficient strength of the functional layer can be obtained.

[0027] The air permeability of the functional layer is 100 cm 3 / cm 2 / sec or more and 500 cm 3 / cm 2 / sec or less is preferred. By setting the air permeability to 500 cm 3 / cm 2 / sec or less, the collection performance of dust and relatively large liquid droplets can be obtained. More preferably, it is 400 cm 3 / cm 2 / sec or less. Even more preferably, it is 350 cm 3 / cm 2 / sec or less. By setting the air permeability to 100 cm 3 / cm 2 / sec or more, the air permeability of the filter medium can be ensured.

[0028] Also, in order to obtain the retention of the pleated shape during filter processing, the Gurley stiffness is preferably 300 mg or more.

[0029] Various known methods can be used to incorporate the functional agent into the functional layer of the present invention. Examples include impregnation, spraying, or kneading the agent onto the fiber surface, or kneading it into the fiber during the manufacturing process. Methods that allow the functional agent to permeate the entire functional layer (e.g., dipping method, impregnation method) or methods that allow it to be applied from the surface of the functional layer (e.g., spraying method, vapor deposition method, gravure transfer method) are preferably used. When two or more functional agents are used in combination, they may be added in the same process or in separate processes. However, if they are added in the same process, the agents may aggregate if they do not mix well with each other, in which case it is preferable to add them in separate processes. An example of adding in separate processes is to knead the functional agent into the resin beforehand, and then, after the nonwoven fabric is manufactured, apply another functional agent by spraying or the like.

[0030] [Liquid repellent layer] The liquid-repellent layer in this invention is characterized by having liquid-repellent properties. Having liquid-repellent properties means that when a certain liquid is dropped onto the surface of a nonwoven fabric, it exhibits the behavior of repelling the droplet. In this application, this means that the surface test liquid tension required for penetration is 35.0 mN / m or less in the wetting tension test liquid defined in JIS K6768 (1999), more preferably 30.0 mN / m or less, and even more preferably 25.0 mN / m or less.

[0031] The liquid-repellent layer's liquid-repellent properties suppress the movement of moisture (mist and droplets) containing bacteria, viruses, mold, and allergens that have passed through the functional layer into the liquid-repellent layer. Furthermore, if the surface test liquid tension of the liquid-repellent layer is 40 mN / m or less, the penetration of water droplets and oil droplets into the liquid-repellent layer can be suppressed. In particular, in the electretization of the liquid-repellent layer described later, the adhesion of water droplets containing ionic components and oil droplets deactivates the electrostatic properties, so suppressing the penetration of water droplets and oil droplets into the liquid-repellent layer is effective in preventing a decrease in the collection performance of the liquid-repellent layer.

[0032] The fibers constituting the liquid-repellent layer are not particularly limited, and synthetic fibers such as polypropylene, polyester, polylactic acid, polyethylene, fluororesin, vinylon, nylon, and rayon can be used, and can be widely used in woven fabrics and nonwoven fabrics, but nonwoven fabrics are preferred in terms of productivity. The method for manufacturing nonwoven fabrics is not particularly limited, but examples include the melt-blown method, spunbond method, thermal bond method, chemical bond method, needle punch method, water-flow entanglement method, air-laid method, and wet papermaking method.

[0033] The thickness of the liquid-repellent layer is preferably 0.01 mm to 0.5 mm. By setting the thickness to 0.5 mm or less, the airflow resistance due to the structure can be sufficiently reduced when the filter material is used in a pleated shape. More preferably, it is 0.4 mm or less. By setting the thickness to 0.01 mm or more, sufficient strength of the liquid-repellent layer can be obtained.

[0034] The diameter of the fibers constituting the liquid-repellent layer is preferably 0.005 to 20 μm, more preferably 0.01 to 10 μm, particularly preferably 0.02 to 5 μm, and most preferably 0.03 to 3 μm. A fiber diameter of 20 μm or less provides a practically sufficient collection efficiency. A fiber diameter of 0.005 μm or more provides sufficient air permeability.

[0035] There are no particular limitations on the method for imparting liquid repellency, but methods such as mixing a liquid repellent into the raw materials when spinning the nonwoven fabric, contacting the nonwoven fabric with a solution containing a liquid repellent, or directly applying the liquid repellent to the nonwoven fabric using methods such as spraying, vapor deposition, or gravure transfer can be used as appropriate.

[0036] The imparting of liquid repellency to the nonwoven fabric may be done on the liquid repellent layer alone before laminating the functional layer and the liquid repellent layer, or after lamination with the functional layer. Preferably, the liquid repellency is imparted before lamination with the functional layer. If the liquid repellency is imparted to the liquid repellent layer alone before lamination, it is possible to prevent a decrease in the antibacterial, antiviral, antifungal, and anti-allergen properties of the functional layer during the liquid repellency imparting process.

[0037] While there are no particular limitations on the type of liquid repellent, those containing fluororesin are preferred. By using a fluororesin-based liquid repellent, the surface test liquid tension required for penetration in the above-mentioned wetting tension test solution can be reduced.

[0038] As for the type of fluororesin, at least one selected from the group consisting of tetrafluoroethylene resin, tetrafluoroethylene-perfluoropropyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, chlorotrifluoroethylene resin, ethylene-tetrafluoroethylene copolymer, vinylidene fluoride resin, vinyl fluoride resin, hexafluoropropylene-vinylidene fluoride copolymer, polyimide-based modified fluororesin, polyphenylene sulfide-based modified fluororesin, epoxy-based modified fluororesin, polyethersulfone-based modified fluororesin, phenol-based modified fluororesin, acrylate polymers having perfluoroalkylethylene groups, and methacrylate copolymers having perfluoroalkylethylene groups can be used.

[0039] The liquid-repellent layer is preferably made of an electrostatically charged nonwoven fabric in order to obtain high breathability and collection performance. As the nonwoven fabric, nonwoven fabrics containing thermoplastic resin fibers or nonwoven fabrics containing natural fibers can be used. Among these, nonwoven fabrics containing thermoplastic resin fibers are preferably used.

[0040] The form of nonwoven fabric containing thermoplastic resin fibers is not particularly limited, but examples include meltblown nonwoven fabrics, spunbond nonwoven fabrics, thermal bond nonwoven fabrics, needle-punched nonwoven fabrics, and airlaid nonwoven fabrics. Among these, meltblown nonwoven fabrics are preferred from the viewpoint that the fiber diameter of the fibers constituting the nonwoven fabric can be reduced, and that there is no oil on the surface of the fibers constituting the nonwoven fabric, or if there is an oil on the surface of the fibers constituting the nonwoven fabric, it is only in a very small amount. Here, examples of oils include silicone-based oils such as dimethylpolysiloxane and mineral oils. Furthermore, when electrostatic treatment is applied to the nonwoven fabric in order to further improve the collection efficiency of the filter material, if an oil is present on the surface of the fibers constituting the nonwoven fabric, the nonwoven fabric tends not to exhibit sufficient electrostatic ability.

[0041] As for the thermoplastic resin fibers, polyolefin fibers are preferred, and polypropylene fibers (hereinafter sometimes referred to as PP fibers) are more preferred, because the nonwoven fabric after the electrostatic treatment described above exhibits excellent electrostatic capacity. Additives to improve the electrostatic effect due to the electrostatic treatment may be included. Known additives can be used as appropriate, but hindered amine-based additives or triazine-based additives are more preferred because they improve the durability of electrostatic force against water and the like. The additive content is preferably in the range of 100 to 30,000 ppm, and more preferably in the range of 7,000 to 15,000 ppm, relative to the total mass of the nonwoven fabric constituting the liquid-repellent layer. If the content is 100 ppm or more, it becomes easier to obtain the desired high level of electrostatic performance. If the content is 30,000 ppm or less, the additive is more easily distributed uniformly in the fibers and does not affect spinnability or film-forming properties.

[0042] Examples of hindered amine compounds include poly[(6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl)((2,2,6,6-tetramethyl-4-piperidyl)imino)hexamethylene((2,2,6,6-tetramethyl-4-piperidyl)imino)] (manufactured by BASF Japan Ltd., "Kimasorb" (registered trademark) 944LD), dimethyl succinate-1-(2 Examples include (-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate (manufactured by BASF Japan Ltd., "Tinuvin" (registered trademark) 622LD) and 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidyl) (manufactured by BASF Japan Ltd., "Tinuvin" (registered trademark) 144).

[0043] Examples of triazine-based additives include poly[(6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl)((2,2,6,6-tetramethyl-4-piperidyl)imino)hexamethylene((2,2,6,6-tetramethyl-4-piperidyl)imino)] (manufactured by BASF Japan Ltd., "Kimasorb" (registered trademark) 944LD), and 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-((hexyl)oxy)-phenol (manufactured by BASF Japan Ltd., "Tinuvin" (registered trademark) 1577FF).

[0044] Here, the PP fiber content in the nonwoven fabric is preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 98% by mass or more, based on the total mass of the nonwoven fabric. The higher the PP fiber content in the nonwoven fabric, the better the electrostatic charge capacity of the nonwoven fabric after electrostatic treatment tends to be.

[0045] When applying electrostatic treatment to a nonwoven fabric, the method is not particularly limited, and any known method of electrostatic treatment can be selected, such as corona discharge, pure water electrostatic treatment, or triboelectric treatment. Among these, the pure water electrostatic treatment, which involves applying water to the nonwoven fabric and then drying it, is preferably used. The timing of the electrostatic treatment is also not particularly limited, and it can be performed before or after liquid-repellent treatment. If the electrostatic properties are deactivated due to the use of solvents during liquid-repellent treatment, it is preferable to perform the treatment after liquid-repellent treatment. Multiple processes can be performed in a single step. That is, the coating of a fluorine-containing polymer and the electrostatic treatment process using a liquid can be performed in a single step.

[0046] In the high-performance filter material of the present invention, it is preferable that the functional layer and the liquid-repellent layer are in contact. Contact between the two layers refers to a state in which the two layers are laminated. The means of lamination may include using a powdered or linear adhesive between the functional layer and the liquid-repellent layer, directly fabricating the liquid-repellent layer on top of the functional layer, or directly fabricating the functional layer on top of the liquid-repellent layer. When laminating the functional layer and the liquid-repellent layer by adhesive, the amount of adhesive should be 1.0 to 20.0 g / m². 2 Preferably, it is 1.0 g / m 2With this level of adhesion, the bonding between the functional layer and the liquid-repellent layer becomes more sufficient, at 20.0 g / m². 2 The following conditions can further suppress the degradation of the functional agent's performance due to the functional agent being covered by the adhesive in the functional layer. Due to the liquid-repellent properties of the liquid-repellent layer, moisture containing bacteria, viruses, mold, and allergens is less likely to penetrate the liquid-repellent layer and more likely to remain in the upstream functional layer, thereby increasing the contact rate with the functional agent and allowing various functions such as antibacterial, antiviral, antifungal, and anti-allergen properties to be expressed efficiently.

[0047] In the high-performance filter material of the present invention, it is preferable that the water absorption height of the functional layer in the Baylec water absorption test is greater than the water absorption height of the liquid-repellent layer in the Baylec water absorption test. Because the water absorption of the functional layer is higher than that of the liquid-repellent layer, moisture containing bacteria, viruses, molds, and allergens that have been repelled by the liquid-repellent layer can be more easily absorbed by the functional layer, and various functions can be expressed more efficiently not only on the laminated surface in contact with the liquid-repellent layer, but also throughout the entire functional layer.

[0048] The high-performance filter material of the present invention is suitable for use in air filter applications, particularly as filters for air purifiers and cabin filters for automobiles, and can be suitably processed into shapes such as pleats and used as a filter unit. To obtain good retention of the pleat shape of the filter, it is more preferable to use fibers with a rigidity of 300 mg or more, as measured by the Gahl method, as the rigidity of the filter material.

[0049] Automotive cabin filters sometimes require flame retardancy, and the functional layer or liquid-repellent layer of the present invention can also be made flame-retardant. Common examples of flame retardants include phosphorus-based flame retardants, nitrogen-based flame retardants, halogen-based flame retardants, bromine-based flame retardants and their composites, magnesium hydroxide, aluminum hydroxide, antimony-based materials, thermally expandable graphite, and silicone-based materials. Flame retardancy can be imparted by adding a flame retardant to the functional layer or liquid-repellent layer, or by using flame-retardant fibers in the fibers constituting the functional layer or liquid-repellent layer. [Examples]

[0050] The present invention will be described more specifically below using examples, but the present invention is not necessarily limited to these examples.

[0051] (1) Inspection Leave the sample at room temperature (24°C, 60% RH) for at least 8 hours to determine its mass, and then calculate the area in square meters. 2 The mass was converted to a unit mass and determined as the basis weight of the sample. The minimum area of ​​the sample was 0.01 m². 2 The number of samples to be evaluated was five, and their arithmetic mean was used as the basis for evaluation.

[0052] (2) Thickness Using a dial thickness gauge (TECLOCK SM-114, probe shape 10mmφ, measuring force 2.5N or less), the measurement frequency was 60cm. 2 We calculated the thickness at 3 locations, for a total of 15 locations, and used the arithmetic mean of these values ​​as the thickness.

[0053] (3) Amount of adhesion The amount of functional agents adhering to the fibers was calculated by measuring the weight of the fibers before the impregnation or before the impregnation, and the weight of the fibers after the impregnation or after the impregnation, under the conditions of (1), and determining the difference.

[0054] (4) Liquid repellency test A 50 μL drop of a wettability tensile strength test mixture (35.0 mN / m, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as defined in JIS K6768 (1999) was dropped onto a 100 mm x 100 mm nonwoven fabric surface from a height of 5 mm, and the penetration was visually confirmed. A sample that did not wet or spread for 30 seconds or more after dropping was marked with a circle (○), and a sample that wetted or spread within 30 seconds was marked with a cross (×).

[0055] (5) Antimicrobial test JIS L 1902 (2015) (Test Methods for Antimicrobial Properties of Textile Products), Annex JA (Normative), Qualitative Test (Halo Method), Sample 615 mm 2 A circular specimen (28 mm in diameter) was placed in the center of an agar plate containing the test bacteria and incubated at 37°C for 24 hours. After incubation, the length of the halo formed around the specimen was measured, and the width of the halo was calculated using the following formula. Harrow width (mm) W = (TD) / 2 T: Sum of the length of the test specimen and the width of the halo (mm) D: Length of the test specimen (mm) The calculated halo width was evaluated according to the following criteria. ◎: Halo width is 3.0 or greater ○: Halo width is 2.0 or greater, but less than 3.0. △: Halo width is greater than 0.0 and less than 2.0 ×: No Hello detected (6) Antifungal test According to JIS Z2911 (2018) (Test method for mold resistance (testing of textile products, wet method)), a mixed spore suspension of molds was inoculated onto the sample, and after incubation for a certain period, the growth of mycelia on the surface of the sample was observed with the naked eye and under a microscope. The sample size was 30 mm x 30 mm, and it was positioned with the functional layer facing upwards, and the mixed spore suspension was inoculated onto the functional layer surface. The molds used in the test were Aspergillus niger, Penicillium citrinum, Chaetomium globosum, and Myrothecium verrucaria, which were mixed in equal volumes to form the mixed spore suspension.

[0056] The observed results were evaluated according to the following criteria. ◎: No mycelial growth is observed in the inoculated area of ​​the sample, and a halo is visible on the culture medium on which the sample is placed. ○: No mycelial growth was observed in the inoculated area of ​​the sample, and no halo was observed on the culture medium on which the sample was placed. △: The area of ​​mycelial growth observed in the inoculated portion of the sample is less than 1 / 3 of the total area. ×: The area of ​​mycelial growth observed in the inoculated portion of the sample exceeds 1 / 3 of the total area. (7) Baylec method water absorption test The water absorption test for textile products was conducted according to JIS L1907 (2010) with a water absorption time of 10 minutes. ○: The water absorption height of the functional layer is greater than the water absorption height of the liquid-repellent layer or the fiber layer. ×: The water absorption height of the functional layer is less than or equal to that of the liquid-repellent layer or the fiber layer. (8) Measurement of solubility in water 500 ml of water was added to a 1 L glass beaker, and the mixture was stirred at 100 rpm using a fluororesin (PTFE) rotor while being kept warm in a 25°C constant temperature bath. 5 g of the functional agent was added, and after 10 minutes, it was visually checked whether the solution was uniformly transparent. If the solution was uniformly transparent after adding 5 g of the functional agent, the solubility in 1 L of water at 25°C was judged to be 10 g or more. If the solution was not uniformly transparent, the solubility in 1 L of water at 25°C was judged to be less than 10 g.

[0057] The water used was pure water with an conductivity of 1 μS / cm or less at 25°C, produced using the G-10DSTSET pure water system manufactured by Organo Corporation.

[0058] [Example 1] (Functional layer) This fabric, weighing 50 g / m², consists of 20% polyester staple fibers with a single fiber fineness of 6.0 dtex, 10% polyester staple fibers with a single fiber fineness of 3.0 dtex, 11% polyester staple fibers with a single fiber fineness of 0.4 dtex, 27% vinylon staple fibers with a single fiber fineness of 6.7 dtex, 16% vinylon staple fibers with a single fiber fineness of 17.0 dtex, and 16% acrylic resin binder. 2 A 0.4 mm thick wet-process nonwoven paper was used as the base fiber sheet.

[0059] A processing solution was prepared by mixing a quaternary ammonium salt (Nikka Chemical Co., Ltd. "Nikkanon RB-40") as an antibacterial agent with a nonionic surfactant (Nikka Chemical Co., Ltd. "Texport SN-10") as a dispersant agent in water. This solution was then placed in an impregnation tank, and the base fiber sheet was passed through the impregnation tank to absorb the processing solution. After passing through an air-through heating furnace, a functional layer was created. The concentration of the processing solution was such that the amount of quaternary ammonium salt adhering to it was 1.0 g / m². 2 I adjusted it so that it would be as follows.

[0060] The solubility of the aforementioned antibacterial agent in 1 liter of water at 25°C was less than 10 g.

[0061] (liquid repellent layer) Using a polypropylene resin containing 0.03% by mass of "Irgaclear" (registered trademark) XT386 (manufactured by BASF Japan Ltd.) [1,3,5-tris(2,2-dimethylpropionylamino)benzene] and 1% by mass of the hindered amine compound "Kimasorb" (registered trademark) 944 (manufactured by BASF Japan Ltd.), the average fiber diameter is 2.0 μm and the basis weight is 30 g / m², produced by melt-blowing. 2 A melt-blown nonwoven fabric was obtained and used as a base fiber sheet.

[0062] A fluororesin aqueous dispersion was prepared by mixing fluororesin processing agent / water / penetrating agent 1 / additive 1 in the following proportions: 40% by mass / 50% by mass / 4% by mass / 6% by mass. AGE100 (manufactured by Asahi Glass Co., Ltd.) was used as the fluororesin processing agent, distilled water as the water, 1-hexanol as the penetrating agent 1, and Delectol MAP (manufactured by Meisei Chemical Industry Co., Ltd.) as the additive 1. The above fluororesin aqueous dispersion was placed in an impregnation tank, and the base fiber sheet was passed through the impregnation tank to impregnate it with the processing solution. After mangle processing, the sheet was passed through a heating furnace at 110°C. The amount of fluororesin impregnated was 1.2 g / m². 2 Next, pure water was sprayed onto the entire nonwoven fabric sheet at high pressure to distribute the pure water evenly, and after draining the water, it was allowed to air dry to obtain an electrostatically charged liquid-repellent layer.

[0063] (filter media) The resulting functional layer is coated with polyethylene hot melt resin at a rate of 3.0 g / m². 2 The material was sprayed in such a manner, passed through a heating furnace, and while the hot-melt resin was melted, it was layered with the liquid-repellent layer to bond the functional layer and the liquid-repellent layer, thereby obtaining a filter material. The evaluation results are shown in Table 1. The obtained filter material had good antibacterial properties.

[0064] [Example 2] (Functional layer) The antibacterial agent used is catechin (Protectia's "Cateprotect NW"), and the concentration of the processing solution is set to 2.0 g / m² based on the amount of catechin adhering to it. 2 The functional layer was obtained in the same manner as in Example 1, except for making adjustments to achieve the desired result.

[0065] The solubility of the aforementioned antibacterial agent in 1 liter of water at 25°C was 10 g or more.

[0066] (liquid repellent layer) A liquid-repellent layer was obtained using the same method as in Example 1. (filter media) A filter material was obtained using the same method as in Example 1. The evaluation results are shown in Table 1. The obtained filter material had high water absorption in the functional layer and very good antibacterial properties.

[0067] [Example 3] (Functional layer) Instead of an antibacterial agent, thiabendazole (M-30, manufactured by Sumika Environmental Science Co., Ltd.) was used as an antifungal agent, and the concentration of the processing solution was set to 1.0 g / m² based on the amount of thiabendazole adhering to it. 2 The functional layer was obtained in the same manner as in Example 1, except for making adjustments to achieve the desired result.

[0068] The solubility of the aforementioned antifungal agent in 1 liter of water at 25°C was less than 10 g.

[0069] (liquid repellent layer) A liquid-repellent layer was obtained using the same method as in Example 1.

[0070] (filter media) A filter medium was obtained using the same method as in Example 1. The evaluation results are shown in Table 1. The obtained filter medium showed good mold resistance.

[0071] [Comparative Example 1] (Functional layer) A functional layer was obtained using the same method as in Example 1.

[0072] (Fiber layer) Using a polypropylene resin containing 0.03% by mass of "Irgaclear" (registered trademark) XT386 (manufactured by BASF Japan Ltd.) [1,3,5-tris(2,2-dimethylpropionylamino)benzene] and 1% by mass of the hindered amine compound "Kimasorb" (registered trademark) 944 (manufactured by BASF Japan Ltd.), the average fiber diameter is 2.0 μm and the basis weight is 30 g / m², produced by melt-blowing. 2A melt-blown nonwoven fabric was obtained and used as a base fiber sheet.

[0073] Next, pure water was sprayed onto the entire nonwoven fabric sheet at high pressure to distribute the water evenly, and after draining the water, it was allowed to air dry to obtain an electrostatically charged fiber layer.

[0074] (filter media) The resulting functional layer is coated with polyethylene hot melt resin at a rate of 3.0 g / m². 2 The material was sprayed in such a manner, passed through a heating furnace, and while the hot-melt resin was molten, it was layered with the fiber layer to bond the functional layer and the fiber layer, thereby obtaining a filter material. The evaluation results are shown in Table 1. The obtained filter material had inferior antibacterial properties compared to Example 1.

[0075] [Comparative Example 2] (Functional layer) The functional layer was obtained using the same method as in Example 3.

[0076] (Fiber layer) A fibrous layer was obtained using the same method as in Comparative Example 1.

[0077] (filter media) A filter material was obtained using the same method as in Comparative Example 1. The evaluation results are shown in Table 1. The obtained filter material had inferior antifungal properties compared to Example 3.

[0078] [Table 1] [Industrial applicability]

[0079] The high-performance filter material of the present invention can be suitably used in air filter applications, particularly as a filter for air purifiers and a cabin filter for automobiles.

Claims

1. A high-performance filter material for an air filter, comprising at least a functional layer and a liquid-repellent layer, The functional layer is located upstream of the airflow. The liquid-repellent layer is positioned downstream of the airflow. The functional layer contains one or more functional agents selected from antibacterial agents, antiviral agents, antifungal agents, and antiallergen agents. The functional agent has a water solubility of 10 g / L or more at 25°C. The aforementioned liquid-repellent layer is an electrostatically charged nonwoven fabric. A high-performance filter material in which the functional layer and the liquid-repellent layer are in contact.

2. The high-performance filter material according to claim 1, wherein the liquid-repellent layer comprises a fluororesin.

3. The high-performance filter material according to claim 1 or 2, wherein the water absorption height of the functional layer in the Baylec water absorption test is greater than the water absorption height of the liquid-repellent layer in the Baylec water absorption test.

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