Essential oil-impregnated carbon porous material, and antibacterial and antiviral agents, antibacterial and antiviral filters, and air purifiers using the same

Abstract

One aspect of the present invention relates to an essential oil-impregnated porous carbon material impregnated with water and an essential oil having antimicrobial activity and / or antiviral activity. The essential oil-impregnated porous carbon material comprises a porous carbon material having a specific surface area determined by the nitrogen adsorption BET method of 500 m2 / g to 2500 m2 / g, an acidic functional group amount of ０.1 meq / g to 5 meq / g, and a pore volume of pores having a size of 2 nm or less of 0.35 cm3 / g or more, the pore volume being determined by analyzing the nitrogen adsorption isotherm obtained in the process of measuring the amount of nitrogen adsorption using the NL-DFT method.

Description

[Technical Field]

[0001] The present invention relates to an essential oil-impregnated carbon porous material and an antibacterial filter and an antiviral filter using the same. [Background technology]

[0002] In recent years, there has been an increasing demand for high functionality and diversification in fields such as air purification. In particular, much research has been conducted into air purification filter media with antibacterial and antiviral properties. Dust-proof filters are known to be used as a means of removing airborne bacteria and viruses. However, such filters alone cannot kill bacteria and viruses that adhere to the filter, and there is a risk that they may multiply on the filter. Furthermore, these filters are only effective against viruses approximately 100 nm in size, such as influenza viruses, and are less effective against relatively small viruses, such as polioviruses, approximately 30 nm in size. Even if the dust-removal effect were enhanced, the increased pressure loss would likely make them difficult to use as filters for masks and other devices.

[0003] In addition to filters, antibacterial agents that impart antibacterial and antiviral effects by using a device that generates hydroxyl radicals or by slowly releasing stabilized radicals or peroxides, as well as general antibacterial agents that contain synthetic chemical substances such as phenols or alcohols, are not recommended for use in products that are carried around at all times as everyday items such as masks, from the standpoint of safety for the human body and ensuring sufficient functionality.

[0004] On the other hand, there are materials that use silver ions as a relatively safe antibacterial agent (e.g., Patent Document 1), but while their antibacterial function is effective against gram-negative bacteria such as Escherichia coli, their antibacterial function is weak against gram-positive bacteria such as Staphylococcus aureus, and their antiviral effect has not yet been confirmed. Another disadvantage is that the material itself is expensive.

[0005] There are also antibacterial agents that use titanium oxide with photocatalytic properties, but because the photocatalytic properties are expressed by ultraviolet or visible light, there are problems with their usage, such as being limited to use during the daytime and in a location where outside light can be taken in, or using a special device such as an ultraviolet lamp in combination (Patent Document 2).

[0006] Furthermore, antibody filters, in which antibodies collected from the eggshells of birds such as chickens are attached to a carrier such as nonwoven fabric, are used in air purifiers and mask filters. However, these antibody filters use antibodies that act only on specific antigens such as influenza viruses, and cannot be expected to be effective against the many other viruses and bacteria that exist in the environment (Patent Document 3).

[0007] For these reasons, there is a need for safe, inexpensive materials that have high antibacterial and antiviral properties.

[0008] In light of this, it has been reported that air purifying filters contain essential oils (such as phytoncides) extracted from natural products as highly safe ingredients for purposes such as deodorization (Patent Document 4). Oils and alcohols evaporate when exposed to air, causing the active ingredients with antibacterial and antiviral properties to quickly disappear, making them difficult to use over long periods of time. To solve this problem, Patent Document 4 discloses incorporating only essential oils into porous particulate materials such as activated carbon and zeolite. However, the method of incorporating only essential oils into porous particulate materials, as in Patent Document 4, did not result in a material that exhibited sufficient antibacterial and antiviral properties.

[0009] Therefore, the present inventors have reported a filter in which magnesium chloride, water, and phytoncide are impregnated onto activated carbon as a material that exhibits sufficient antibacterial and antiviral effects (Patent Document 5).

[0010] However, although the antibacterial and antiviral agent disclosed in Patent Document 5 has high antibacterial and antiviral properties, when an excess of water is present due to the coexistence of inorganic salts such as magnesium chloride with water, hydrolysis occurs, resulting in a decrease in antibacterial and antiviral properties as a result of water consumption, and depending on the external environment such as temperature and humidity, the evaporation of water can cause the essential oil to volatilize, resulting in a loss of active ingredients, and there is still room for improvement in the long-term stability of performance depending on the external environment. There is also room for improvement in the antibacterial and antiviral properties. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-285348 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-246208 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-030951 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-172156 [Patent Document 5] WO2015 / 104894 publication Summary of the Invention

[0012] An object of the present invention is to provide an essential oil-impregnated carbon porous material having excellent antibacterial and antiviral properties, and an antibacterial and antiviral filter and air purifier incorporating the same.

[0013] An essential oil-impregnated porous carbon material according to one aspect of the present invention is an essential oil-impregnated porous carbon material impregnated with water and an essential oil having at least one of an antibacterial activity and an antiviral activity, and the carbon porous material constituting the essential oil-impregnated porous carbon material has a specific surface area of ​​500 m2 as measured by a nitrogen adsorption BET method. 2 / g or more 2500m 2 / g or less, the amount of acidic functional groups is 0.1 meq / g or more and 5 meq / g or less, and the pore volume of pores with a pore diameter of 2 nm or less, obtained by analyzing the adsorption isotherm obtained by measuring the amount of nitrogen adsorption using the NL-DFT method, is 0.35 cm 3 / g or more. DETAILED DESCRIPTION OF THE INVENTION

[0014] Research by the present inventors has revealed that the antibacterial activity of essential oils such as phytoncides is reduced or lost unless a certain proportion of moisture is present. As a result of extensive research, the present inventors have found that the above-mentioned object can be achieved by using an essential oil-impregnated carbon porous material having the above-mentioned configuration.

[0015] According to the present invention, it is possible to provide an essential oil-impregnated carbon porous material that provides an antibacterial agent and an antiviral agent that can exhibit excellent antibacterial and antiviral effects, and an antibacterial and antiviral filter and an air purifier that include the same.

[0016] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0017] [Essential oil impregnated carbon porous material] The essential oil-impregnated porous carbon material of this embodiment is composed of a specific porous carbon material, water, and essential oil.

[0018] The specific surface area of ​​the carbon porous material constituting the essential oil-impregnated carbon porous material of this embodiment is 500 m by the BET method. 2 / g or more, preferably 700m 2 / g or more, more preferably 800m 2 The specific surface area of ​​the carbon porous material used in this embodiment, as measured by the BET method, is 2500 m 2 / g or less, preferably 2200m 2 / g or less, and more preferably 2000m 2 / g or less. When the specific surface area by the BET method is equal to or greater than the lower limit, the impregnation state of the essential oil and water can be maintained in a suitable manner, and volatilization of the essential oil components can be suppressed. On the other hand, when the specific surface area by the BET method is equal to or less than the upper limit, the mechanical strength of the carbon material can be maintained, it can be processed in a suitable manner, and a decrease in the probability of contact between bacteria or viruses and the essential oil components, which is caused by the essential oil components being adsorbed inside the porous carbon by capillary action, can be suppressed.

[0019] The amount of acidic functional groups in the carbon porous material constituting the essential oil-impregnated carbon porous material of this embodiment is 0.1 meq or more, preferably 0.2 meq / g or more. The amount of acidic functional groups in the carbon porous material is 5 meq / g or less, preferably 4 meq / g or less. When the amount of acidic functional groups is above the lower limit, the carbon porous material has excellent affinity with water, thereby suppressing water evaporation, and the essential oil-impregnated carbon porous material can maintain its antibacterial and antiviral activity for a long period of time. When the amount of acidic functional groups is 5 mq / g or less, the carbon porous material has excellent affinity with essential oil components, allowing the essential oil components to be suitably retained on the surface of the carbon porous material, and the essential oil-impregnated carbon porous material can maintain its antibacterial and antiviral activity for a long period of time. The amount of acidic functional groups in activated carbon can be quantified using a commonly known method (see, for example, "Surfaces, Vol. 34, No. 2 (1996)" and "Catal. 16, 179 (1966)"). Specifically, the amount of acidic functional groups can be determined by placing 2 g of each activated carbon sample in a 100 ml Erlenmeyer flask, adding 50 ml of 1 / 10 N alkaline reagent (sodium ethoxide), shaking for 24 hours, filtering, and titrating the unreacted alkaline reagent with 1 / 10 N hydrochloric acid. Specifically, the amount can be determined by the method described in the Examples below.

[0020] The carbon porous material of this embodiment preferably has a hydrogen content of 0.21% by weight or more, and more preferably 0.3% by weight or more. Furthermore, the hydrogen content is preferably 1.0% by weight or less, and more preferably 0.8% by weight or less. The hydrogen content indicates the terminal amount of the carbon skeleton, i.e., the size of the carbon structure. In this embodiment, a hydrogen content of less than the upper limit is preferred because the carbon structure is sufficiently developed and the impregnation of essential oils can be maintained favorably, while a hydrogen content of more than the lower limit can maintain the impregnation of water favorably. Here, the hydrogen content can be measured by the method (elemental analysis) described in the Examples below.

[0021] The pore volume of pores with a pore diameter of 2 nm or less (hereinafter sometimes abbreviated as micropore volume) obtained by analyzing the adsorption isotherm obtained by measuring the nitrogen adsorption amount of the carbon porous material constituting the essential oil-impregnated carbon porous material of this embodiment using the NL-DFT method was 0.35 cm 3 / g or more, preferably 0.36 cm 3 The micropore volume of the carbon porous material used in the present invention is preferably 0.42 cm3 / g or more. 3 / g or less, and more preferably 0.40 cm 3 / g or less. Here, the micropores refer to pores with a pore size (pore diameter) of 2 nm or less, and the micropore volume can be calculated by analyzing the adsorption isotherm obtained by measuring the amount of nitrogen adsorption using the NL-DFT method. In the present invention, the micropore volume is 0.35 cm 3 / g or more, the essential oil and water can be suitably maintained in a state where they are attached to the carbon porous material, the evaporation of the essential oil and water can be suppressed, and the antibacterial and antiviral activities can be suitably maintained.

[0022] The essential oil-impregnated porous carbon material of this embodiment, or the carbon porous material that constitutes it, has the specific surface area, micropore volume, and amount of acidic functional groups measured by the BET method described above, which makes it easier for bacteria and viruses to be captured and contacted by the essential oil-impregnated porous carbon material, and also makes it possible for the essential oil and water to come into contact efficiently, thereby fully exerting antibacterial and antiviral effects. Furthermore, the essential oil-impregnated porous carbon material of this embodiment can maintain the impregnated state of the essential oil and water appropriately, allowing it to stably exert antibacterial and antiviral effects for a long period of time.

[0023] The raw materials for the carbon porous material used in this embodiment are not particularly limited as long as they satisfy the properties of the resulting carbon porous material. Examples include plant-based materials such as wood, sawdust, charcoal, fruit shells such as coconut shells and walnut shells, fruit seeds, pulp manufacturing by-products, lignin, and blackstrap molasses; mineral-based materials such as peat, grass peat, lignite, brown coal, litholytic coal, anthracite, coke, coal tar, coal pitch, petroleum distillation residue, and petroleum pitch; synthetic materials such as phenol, saran, and acrylic resin; and natural materials such as recycled fiber (rayon). The raw materials can be carbonized and activated as needed to obtain the carbon porous material. Activation methods include combustion gas activation, carbon dioxide activation, and steam activation.

[0024] When steam activation is performed, the steam concentration in the gas used for activation is set to a range of 10 to 80%, more preferably 20 to 50%. The activation temperature is not particularly determined because it depends on the steam content, but is usually set to a range of 600 to 1000°C, more preferably 700 to 980°C, in order to prevent excessive oxidation of the carbon porous material.

[0025] Furthermore, in this embodiment, it is preferable to cool the carbon porous material after activation in a gas of the same composition as the activation gas until the temperature of the carbon porous material reaches 300°C or less, and then remove it from the system. The gas similar to the activation gas, which is the atmosphere required for cooling, may be an atmosphere of nitrogen gas, carbon dioxide gas, or a mixture of these gases (with an oxygen and hydrogen content of 1 to 2% or less) used during activation, and the gas used for activation and the gas used for cooling do not necessarily have to have the same composition. This prevents the functional groups on the surface from being removed during cooling, and allows the material to be stably removed.

[0026] The carbon porous material may be in any form, such as powder, granules, or fibers (threads, woven fabric (cloth), felt, etc.). When used in applications such as air purifier filters or masks, it is preferable to use an activated carbon sheet in which the activated carbon is bonded to a filter substrate such as a nonwoven fabric; a molded product in which the activated carbon is molded with a binder into a plate, honeycomb, cylinder, columnar, or other shape; or a filter-shaped can in which the carbon porous material is filled.

[0027] When a powdered carbon porous material is used to form a sheet, the average particle size is preferably 10 μm to 150 μm, more preferably 20 μm to 75 μm, from the viewpoints of workability and contact efficiency with essential oil components, etc. When granular activated carbon is used, for the same reasons, the average particle size is preferably 75 μm to 1.7 mm (200 mesh to 10 mesh), more preferably 100 μm to 0.5 mm. When fibrous activated carbon is used, it is preferably cut into pieces of about 1 to 5 mm for moldability. Here, the average particle size refers to D50 as measured by laser diffraction.

[0028] The essential oil constituting the essential oil-impregnated carbon porous material of this embodiment may be chemically synthesized or derived from natural products, as long as it has at least one of antibacterial and antiviral properties. Naturally extracted chemicals derived from natural products are more preferable because they are relatively safe and have little impact on the environment.

[0029] Chemically synthesized ones include phenol, isopropylmethylphenol, resorcinol, parahydroxybenzoic acid esters, phenoxyethanol, thymol, cresol, hinokitiol, benzoic acid, salicylic acid, dehydroacetic acid, hexachlorophene, undecylenic acid monoethanolamide, benzalkonium chloride, benzethonium chloride, chlorhexidine gluconate, and lysozyme chloride.

[0030] Examples of natural plant-derived extracts include various essential oils extracted from at least one type of plant such as cypress, Japanese cypress, oak, ginkgo, bamboo grass, nandina, eucommia, turmeric, asarum, juniper, sandalwood, Abies sachalinensis, black pine, spruce, cedar, spruce, arborvitae, fir, camphor tree, mandarin orange, myrtle, osmanthus, tea tree, eucalyptus, cedarwood, acacia, juniper, thyme, pine, peppermint, lavender, parsley, and rice, but are not limited to the above plant species as long as the plant can be used to extract essential oils. Preferred are essential oils extracted from these plants, such as aloe extract, Scutellaria root extract, Phellodendron bark extract, Katsumire, peony extract, gardenia extract, artemisia capillaris extract, Lithospermum root extract, Sanzan extract, peppermint, mulberry extract, rosemary extract, lavender extract, speril, honeysuckle, hinokitiol, and itan root, which contain active ingredients known as phytoncides that possess antibacterial and antiviral functions. Among these, essential oils containing at least one organic substance selected from terpenoids, phenylpropanoids, flavonoids, alkaloids, phenols, alcohols, steroids, heterocycles, esters, ethers, ketones, aldehydes, fatty acids, and mixtures thereof are particularly preferred.

[0031] In this embodiment, it is particularly preferable to use essential oils with excellent antibacterial and antiviral properties, such as phytoncides, which contain a large amount of the above organic substances, tea tree oil, eucalyptus oil, patchouli oil, and peppermint oil. Phytoncides, in particular, have long been known as wood extracts with antibacterial properties. It is believed that plants possess compounds called phytoncides as self-defense substances to protect themselves from bacteria. Phytoncides contain over 100 types of organic natural substances, and when they coexist, they are thought to be able to act on a wide variety of bacteria and viruses.

[0032] Terpenoids are known to have antibacterial, antiviral, disinfectant, antibacterial, and preservative properties. Generally, compounds with more hydroxyl groups are said to have stronger antibacterial and antiviral effects, so it is thought that if a product contains compounds with many hydroxyl groups, it will have stronger antibacterial and antiviral effects.

[0033] In addition, essential oil components that are thought to have antibacterial and antiviral effects have been confirmed to include alcohols such as benzyl alcohol and phenethyl alcohol, long-chain alcohols such as dodecanol and hexadecanol, phenols such as phenol, cresol, ethylphenol, propylphenol, thymol, eugenol, guaiacol, creosol, methoxyphenol, and dimethoxyphenol, fatty acids such as acetic acid, lauric acid, palmitic acid, myristic acid, caprylic acid, propionic acid, and butyric acid, esters such as bornyl acetate, isobornyl acetate, geranyl acetate, benzyl acetate, and linalyl acetate, and aldehydes such as neral and geranial.

[0034] In this embodiment, the amount of essential oil impregnated is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and even more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the carbon porous material constituting the essential oil-impregnated carbon porous material. Furthermore, the amount of essential oil impregnated is preferably 300 parts by mass or less, preferably 280 parts by mass or less, and preferably 250 parts by mass or less, relative to 100 parts by mass of the carbon porous material constituting the essential oil-impregnated carbon porous material. Alternatively, the amount may be 100 parts by mass or less, 50 parts by mass or less, 30 parts by mass or less, 25 parts by mass or less, 23 parts by mass or less, or 20 parts by mass or less. When the amount is above the lower limit, antibacterial activity and antiviral activity are suitably expressed, while when the amount is below the upper limit, surface wetting and stickiness are suppressed, resulting in excellent handleability, which is preferred.

[0035] The essential oil-impregnated carbon porous material of this embodiment is impregnated with water. This is because impregnation of water allows the antibacterial and antiviral effects of the essential oil impregnated in the essential oil-impregnated carbon porous material to be fully exerted. The amount of water impregnated in the essential oil-impregnated carbon porous material is preferably an amount that can form micellar particles with the essential oil impregnated on the essential oil-impregnated carbon porous material, or an amount that does not cause phase separation between the water and the essential oil. While the reason for this is not entirely clear, it is presumed that the water impregnated in the essential oil-impregnated carbon porous material forms a micellar structure with the essential oil, allowing the antibacterial and antiviral components in the essential oil to exert their antibacterial and antiviral effects. To confirm whether the amount of water and essential oil that does not cause phase separation can be confirmed by visually observing whether an interface between the oil phase and the water phase is observed when an essential oil composition containing water, essential oil, and optionally a surfactant is prepared.

[0036] The amount of water impregnated into the essential oil-impregnated carbon porous material of this embodiment is preferably 20 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, and particularly preferably 60 parts by mass or more, relative to 100 parts by mass of the carbon porous material constituting the essential oil-impregnated carbon porous material. The amount is preferably 300 parts by mass or less, and more preferably 200 parts by mass or less. Generally, the carbon porous material constituting the essential oil-impregnated carbon porous material can naturally adsorb 7 to 20 parts by mass of water relative to 100 parts by mass of the carbon porous material. In this embodiment, although the cause is unclear, it is known that the presence of moisture significantly affects antibacterial and antiviral activity. Therefore, it is presumed that moisture trapped within the pores and unable to move freely will not be able to exhibit the functions of the present invention. Therefore, it is preferable that the porous carbon material having the characteristics of the carbon material of this embodiment has a moisture content greater than the naturally adsorbed moisture. Whether or not the amount of water contained in the essential oil-impregnated carbon porous material of this embodiment is greater than or equal to the amount of water that can be naturally adsorbed can be confirmed by comparing the amount of water contained in the carbon porous material before the essential oil is impregnated.

[0037] The essential oil-impregnated porous carbon material of this embodiment has essential oil and water impregnated therein, and although the state of impregnation is not entirely clear, it is presumed that the essential oil, water, and, if necessary, surfactant and / or moisturizing substance are mixed within the pores to form a micellar state or a membrane structure. By forming such a micellar state or membrane structure within the pores, the essential oil and water are stably maintained in an impregnated state on the porous carbon material constituting this embodiment, while bacteria and viruses are suitably captured, and the water necessary for the antibacterial and antiviral effects of the essential oils is supplied sufficiently and stably, resulting in the long-term stable exertion of antibacterial and antiviral effects.

[0038] The carbon porous material of this embodiment retains water due to the action of its pores and acidic functional groups composed of oxygen, hydrogen, etc., but the addition of a surfactant can increase its affinity with water, resulting in stable water adsorption. Furthermore, the surfactant suppresses phase separation, thereby preventing a decrease in the retention of essential oils and water on the carbon porous material. For these reasons, a surfactant may be further impregnated into the essential oil-impregnated carbon porous material of this embodiment.

[0039] It is believed that when a surfactant is present, essential oils, water, and surfactants tend to form membrane structures or micelles within the pores of the carbon porous material, and that essential oil components can be incorporated into these membrane structures or micelles. The surface of micelles is hydrophilic, and it is thought that they can efficiently contact the hydrophilic bacterial biomembrane of bacteria and viruses that have arrived from outside. The micelles are thought to assimilate with the bacterial biomembrane, and their phytoncide components can denature proteins inside the biomembrane or destroy the biomembrane itself, which is the same antibacterial action as antibacterial peptides and phenolic antibacterial agents.

[0040] Furthermore, even in the absence of surfactants, fatty acids, which are one of the components contained in essential oils (especially phytoncides), are thought to function as surfactants. Therefore, it is estimated that the same antibacterial activity as antibacterial peptides and phenolic antibacterial agents can be exhibited even without surfactants, but the addition of surfactants is thought to produce a more efficient antibacterial effect.

[0041] Such surfactants can be used without any particular limitation as long as they do not impair the effects of the present invention, but anionic surfactants, nonionic surfactants, or amphoteric surfactants are particularly preferred. This is because the use of materials that are also used in dishwashing detergents and food additives and have been proven to be relatively safe for the human body makes it possible to produce essential oil-impregnated porous carbon materials more safely and at lower cost.

[0042] More specific examples of such surfactants that can be used include alkylbenzenesulfonates, monoalkylphosphates, alkylpolyoxyethylene sulfates, monoalkyl sulfates, soaps, alkyldimethylamine oxides, alkylcarboxybetaines, polyoxyethylene alkyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters (polysorbates), glycerin fatty acid esters, polyoxyethylene fatty acid esters, and the like.

[0043] When the essential oil-impregnated carbon porous material of this embodiment contains a surfactant, the surfactant content is approximately 0.01 to 2.0 times the weight of the essential oil. If the surfactant content is less than 0.01 times, the wettability of the porous material decreases, and the essential oil components tend to be somewhat less likely to be impregnated. On the other hand, if the surfactant content exceeds 2.0 times, the viscosity of the essential oil composition increases, which may also make it difficult for the essential oil components to be impregnated into the porous material. From this perspective, it is believed that excellent antibacterial and antiviral effects can be efficiently exhibited if the surfactant content is in the range of 0.01 to 2.0 times the weight of the porous material.

[0044] Furthermore, in this embodiment, a moisturizing substance may be added to suppress water evaporation. The moisturizing substance is not particularly limited and may be either organic or inorganic. Examples of organic substances that can be used include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, and cellulose. Examples of inorganic substances that can be used include oxides such as silicon oxide, aluminum oxide, titanium oxide, calcium oxide, and magnesium oxide, as well as composites thereof, and metal hydroxides such as calcium hydroxide, magnesium hydroxide, and titanium hydroxide. These absorb moisture, and when incorporated into the essential oil composition described below, they can reduce vapor pressure and suppress water evaporation. This allows the essential oil-impregnated carbon porous material to retain moisture. Therefore, it is believed that excellent antibacterial and antiviral effects can be maintained for a long period of time. Furthermore, since the material does not contain elements such as halogens, boron, and sulfur, it is preferable because it does not emit harmful substances due to moisture absorption or heat.

[0045] The content of the moisturizing substance is preferably 0.1 to 1.0 times the weight of the porous carbon material. If the content of the moisturizing substance is 0.1 times or more the weight of the porous carbon material, the moisturizing properties improve, and the antibacterial and antiviral effects tend to improve. On the other hand, if the content is 1.0 times or less, the porous carbon material or essential oil will be saturated, which tends to prevent crystal precipitation.

[0046] Note that the moisture-retaining substance may be prone to precipitation depending on the conditions of use and the substance selected, and in such cases, it is a preferred embodiment to set the content of the moisture-retaining substance relative to the carbon porous material in a mass ratio of less than 0.1. In the case of the metal hydroxides listed above or inorganic substances other than metal hydroxides, for example, metal chlorides such as magnesium chloride, precipitation tends to occur easily, and the content of the metal chloride relative to the carbon porous material is preferably less than 0.1, more preferably less than 0.05, or may be 0 (i.e., not included).

[0047] The method for producing the essential oil-impregnated porous carbon material of this embodiment is not particularly limited, and the material can be prepared by a conventionally known method. For example, the following preparation method can be used.

[0048] First, an essential oil composition (impregnation liquid) is prepared by mixing essential oil, water, and, if necessary, a surfactant, a moisturizing substance, etc. In this case, it is preferable to mix the components so that the weight of each component relative to the porous material will be the above-mentioned blend ratio after impregnation, and prepare the essential oil composition (impregnation liquid).

[0049] Next, the essential oil composition (impregnation liquid) is impregnated onto the carbon porous material. The impregnation method can be a method using a spray device that can spray a fixed amount of the essential oil composition, a shower device that can sprinkle the essential oil composition, or a method of immersing the material in a water tank containing the essential oil composition for a fixed period of time and then draining the liquid.

[0050] When the carbon porous material is in powder or granular form, the essential oil composition (impregnated liquid) can be uniformly mixed by spraying or dropping the essential oil composition onto the activated carbon while stirring it with a mixer or the like, thereby obtaining an essential oil-impregnated carbon porous material.

[0051] When the carbon porous material is in the form of fibers or a molded product such as a sheet, felt, or fabric, it is easier to impregnate it using a batch method or a continuous method, such as a method using a conveyor impregnation device having a sheet delivery mechanism.

[0052] Specifically, the essential oil composition is applied by a sponge roll or a brush that can adequately hold the essential oil composition, or by applying the essential oil composition evenly or by dropping it.

[0053] In this case, compression, squeezing, and reapplication may be repeated to spread the essential oil composition evenly over the entire carbon porous material sheet, but a simpler and more efficient method is to measure the weight of each component in the essential oil composition so that it ultimately contains the above-mentioned ratio.

[0054] In this embodiment, the temperature at which the essential oil composition is applied is not particularly limited, and is within a range in which the vapor pressure of water does not increase significantly and which does not interfere with application by freezing or the like, i.e., in the range of 4°C to 80°C, more preferably in the range of 10°C to 60°C, and even more preferably in the range of 20°C to 60°C.

[0055] The atmosphere in which the essential oil composition (impregnation liquid) is impregnated is not particularly limited, and the impregnation may be carried out in air or in an inert gas. In particular, when the impregnation is carried out at a high temperature, it is preferable to carry out the impregnation in an inert gas.

[0056] To prevent the obtained essential oil-impregnated porous carbon material from drying, it is preferable to immediately place it in a zip-top bag or the like after preparation, seal it, and store it as is until immediately before use.

[0057] Alternatively, a powdery or granular carbon porous material may be supported on a substrate sheet to produce a filter (sheet) comprising the carbon porous material, and the essential oil composition may be impregnated onto the carbon porous material on the filter in the same manner as in the case of the above-mentioned molded carbon porous material in the form of a sheet, felt, or fabric. In this case, the substrate may be a filter substrate having a three-dimensional network skeleton structure, and examples thereof include various filter substrates having a three-dimensional network skeleton structure such as porous urethane (polyurethane foam sheet), nonwoven fabric, fabric, and mesh, with polyurethane foam sheet being preferred. In addition, a method for supporting the carbon porous material on the substrate may involve immersing the substrate in a suspension in which an adhesive substance and the carbon porous material are dispersed or dissolved in water, and then applying a solution until the basis weight of the carbon porous material reaches the desired value (preferably 100 g / m). 2 ~200g / m 2 ), and then drying (preferably at 100°C to 200°C for 0.1 to 6 hours) can be performed to obtain a filter comprising a carbon porous material.

[0058] [Antibacterial and / or antiviral agents] The essential oil-impregnated porous carbon material of this embodiment as described above can be used in various applications as an antibacterial agent and / or an antiviral agent.

[0059] For example, the filter can be used for applications such as air purifier filters, mask filters, air conditioner filters, humidifier filters, car air conditioner filters, vacuum cleaner filters, garbage disposal filters, and refrigerator filters.

[0060] The antibacterial agent and / or antiviral agent of the present embodiment contains naturally derived ingredients that are gentle on the human body, and can retain their active ingredients for a long period of time. Therefore, it is believed that excellent effects can be achieved by supporting the agent in filters used in air purifiers, masks, and the like.

[0061] For example, an antibacterial and / or antiviral filter can be provided by supporting an antibacterial and / or antiviral agent made of the essential oil-impregnated carbon porous material of this embodiment on a filter substrate having a three-dimensional network skeleton structure.

[0062] The filter substrate that can be used in the antibacterial and / or antiviral filter of this embodiment is not particularly limited as long as it is a substrate having a three-dimensional network skeleton structure that can support the essential oil-impregnated carbon porous material as described above.

[0063] Specifically, examples include various filter substrates having a three-dimensional network skeleton structure, such as porous urethane, nonwoven fabric, woven fabric, and mesh, which are highly breathable and easily support the essential oil-impregnated carbon porous material of this embodiment. Commercially available products may be used, and suitable porous urethanes include 1301WH2.2t manufactured by Kurabo, ECZ 10t manufactured by Inoac, and MF-13 manufactured by Inoac. Suitable nonwoven fabrics include KC130 manufactured by Kurashiki Seni Kako. Suitable mesh substrates include PH3734, PH3232, and EH3433 manufactured by Mizutaka.

[0064] The antibacterial and / or antiviral filters described above can be obtained, for example, by dispersing an essential oil-impregnated carbon porous material or a carbon porous material in a certain amount of water, adding latex (LX812 manufactured by Zeon Corporation) as an adhesive and cellulose (Cellogen WSA manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as a thickener to prepare a slurry, and then impregnating the various filter substrates described above with this slurry and drying them. Note that when a carbon porous material is used as the slurry to be impregnated during filter production, the essential oil composition is impregnated after the filter is produced.

[0065] Furthermore, when these filters are provided in air purifiers, air conditioners, etc. and brought into contact with airflow, they can efficiently exhibit antibacterial and antiviral functions.

[0066] As described above, this specification discloses various aspects of the technology, but the main technologies among them are summarized below. That is, the essential oil-impregnated porous material according to one aspect of the present invention is an essential oil-impregnated porous carbon material impregnated with water and an essential oil having at least one of an antibacterial activity and an antiviral activity, and the carbon porous material constituting the essential oil-impregnated porous carbon material has a specific surface area of ​​500 m2 as measured by the nitrogen adsorption BET method. 2 / g or more 2500m 2 / g or less, the amount of acidic functional groups is 0.1 meq / g or more and 5 meq / g or less, and the pore volume of pores with a pore diameter of 2 nm or less, obtained by analyzing the adsorption isotherm obtained by measuring the amount of nitrogen adsorption using the NL-DFT method, is 0.35 cm 3 / g or more.

[0067] With this configuration, it is possible to provide an essential oil-impregnated carbon porous material that provides an antibacterial agent and an antiviral agent that can exhibit excellent antibacterial and antiviral effects, as well as an antibacterial and antiviral filter and an air purifier that include the same.

[0068] It is preferable that the essential oil-impregnated carbon porous material further be impregnated with a surfactant, which allows the carbon porous material to stably adsorb water and also suppresses phase separation, thereby preventing a decrease in the retention of essential oil and water on the carbon porous material.

[0069] In the essential oil-impregnated carbon porous material, the essential oil is preferably a natural extract derived from a plant, which has the advantages of being relatively safe and having little impact on the environment.

[0070] Furthermore, in the essential oil-impregnated porous carbon material, the content of the metal chloride relative to the amount of the porous carbon material is preferably less than 0.1 times by mass, which is thought to suppress precipitation of the metal chloride.

[0071] Furthermore, an antibacterial agent and an antiviral agent according to a further aspect of the present invention are characterized in that they comprise the essential oil-impregnated carbon porous material described above.

[0072] Furthermore, a filter according to yet another aspect of the present invention is characterized by comprising the above-mentioned antibacterial agent or antiviral agent.

[0073] The present invention also includes an air cleaner equipped with the above-mentioned filter. [Example]

[0074] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0075] (Specific surface area and micropore volume of carbon porous materials by nitrogen adsorption BET method) Below is an approximate formula derived from the BET formula.

[0076]

number

[0077]

number

[0078] Using the approximate formula (I) above, we substitute the amount of adsorption (v) measured at a given relative pressure (p / p0) by the multipoint method using nitrogen adsorption at liquid nitrogen temperature to obtain v. m The specific surface area (SSA: unit is m 2 / g) was calculated. m is the amount of adsorption (cm) required to form a monolayer on the sample surface. 3 / g), and v is the measured adsorption amount (cm 3 / g), p0 is the saturated vapor pressure, p is the absolute pressure, c is a constant (reflecting the heat of adsorption), and N is Avogadro's number 6.022 × 10 23 , a(nm 2) is the area occupied by the adsorbate molecule on the sample surface (molecular occupied cross-sectional area).

[0079] Specifically, the amount of nitrogen adsorption to the carbon porous material at liquid nitrogen temperature was measured using an "Autosorb-iQ-MP" manufactured by Quantachrome, as follows: The carbon material serving as the measurement sample was filled into a sample tube, and the sample tube was cooled to -196°C. The pressure was then reduced once, and nitrogen (purity 99.999%) was then adsorbed onto the measurement sample at the desired relative pressure. The amount of nitrogen adsorbed by the sample when equilibrium pressure was reached at each desired relative pressure was taken as the amount of adsorbed gas v. The specific surface area was calculated using the BET method based on the obtained value.

[0080] The adsorption isotherm obtained by measuring the amount of adsorbed nitrogen was analyzed by the NL-DFT method, and the volume of pores having a pore diameter of 2 nm or less was calculated as the micropore volume.

[0081] (Measurement of the amount of acidic functional groups in carbon porous materials) The amount of acidic functional groups in carbon porous materials can be determined by the method detailed in Surface, 34[2] (1996) Otowa, p. 62 or Catal., 1966

[16] (USA), p. 179. Specifically, 2 g of activated carbon sample is placed in a 100 mL Erlenmeyer flask, 50 mL of 1 / 10 N alkaline reagent (sodium ethoxide) is added, and the mixture is shaken for 24 hours, followed by filtration. The unreacted alkaline reagent is then titrated with 1 / 10 N hydrochloric acid. In this method, oxygen-derived functional groups react with sodium ethoxide, and the remaining sodium ethoxide is quantified with hydrochloric acid to determine the amount of acidic functional groups.

[0082] (Measurement of hydrogen content in carbon porous materials: elemental analysis) Elemental analysis was performed using an oxygen, nitrogen, and hydrogen analyzer EMGA-930 manufactured by Horiba Ltd. based on the inert gas dissolution method. The detection method of this device is hydrogen: inert gas fusion - non-dispersive infrared absorption method (NDIR), and calibration is performed using a Ni capsule and TiH2 (H standard sample). As a pretreatment, 20 mg of a sample whose moisture content had been measured at 250°C for approximately 10 minutes was placed in the Ni capsule and measured after degassing for 30 seconds in the elemental analyzer. The test was performed on three samples, and the average value was used as the analytical value.

[0083] [Manufacturing Example 1] <Preparation of carbon porous materials> 100 parts by weight of coconut shell carbonized material, finely pulverized to 200 mesh or less, was mixed with 40 parts by weight of water containing 2 parts by weight of CMC, and gently granulated into spherical particles using a dish granulator. The resulting granules were dried. A moving bed was formed from top to bottom while the granules were heated, and heavy oil gas vaporized at 350°C was continuously blown into the vaporized hydrocarbon inlet at a ratio of 40 parts per 100 parts of granules. The heat treatment temperature was 950°C, and the granules were held at that temperature for 30 minutes.

[0084] Next, the above granular carbon material was activated using combustion gas from liquefied propane gas at a temperature of 900°C for 1 hour. After that, the temperature was lowered to 200°C while maintaining the same atmosphere, to produce a porous carbon material. The physical properties of the obtained porous carbon material are shown in Table 1.

[0085] <Preparation of a filter with a carbon porous material> Next, 100 parts by mass of the obtained carbon porous material was dispersed in 120 parts by mass of water, and a suspension was prepared by adding 40 parts of a 2% by mass CMC aqueous solution and 260 parts of a 45% by mass acrylonitrile butadiene latex as adhesives. A polyurethane foam sheet (3 mm thick, polyurethane basis weight 80 g / m) was used. 2 ) was immersed in a carbon porous material suspension, and the carbon porous material was immersed in a suspension having a weight per unit area of ​​150 g / m 2 After squeezing the filter to a thickness of 1000 ml, it was dried at 120°C to obtain a filter comprising a carbon porous material.

[0086] [Manufacturing Example 2] A carbon porous material was obtained in the same manner as in Production Example 1, except that the activation time was changed to 2 hours, and then a filter comprising the carbon porous material was obtained.

[0087] [Manufacturing Example 3] A carbon porous material was obtained in the same manner as in Production Example 1, except that the activation time was changed to 3 hours, and then a filter comprising the carbon porous material was obtained.

[0088] [Manufacturing Example 4] A carbon porous material was obtained in the same manner as in Production Example 1, except that after activation, the gas flow was switched to nitrogen and the temperature was maintained at 900°C for 1 hour, and then a filter comprising the carbon porous material was obtained.

[0089] [Manufacturing Example 5] A carbon porous material was obtained in the same manner as in Production Example 1, except that in Production Example 1, the activation time was 4 hours, and then the temperature was lowered to 200°C and the holding time at 200°C was 2 hours. Then, a filter comprising the carbon porous material was obtained.

[0090] Table 1 shows the specific surface area, acidic functional group, hydrogen content, and micropore volume measured by the BET method of the carbon porous materials obtained in Production Examples 1 to 5.

[0091] [Table 1]

[0092] [Examples 1 to 3] The above-mentioned phytoncide solution (essential oil, Phytoncide Japan "PT-150", water content 99.7%) preparation was evenly applied using a sponge roller to the filters (100 x 120 mm, activated carbon weight 1.08 g) equipped with carbon porous materials in Production Examples 1 to 3, to prepare the filters equipped with phytoncide-impregnated carbon porous materials in Examples 1 to 3, respectively. The filters equipped with phytoncide-impregnated carbon porous materials were repeatedly compressed, squeezed, and re-impregnated to ensure that the impregnating solution was evenly distributed over the entire sheet, and the weight was adjusted so that approximately 2 g of essential oil composition was finally added to the filters equipped with carbon porous materials. The weight of the filter itself before the impregnation operation was 1.8 g, and the weight gain after the impregnation operation was 2 g, 2.4 g, and 2.7 g in Examples 1 to 3, respectively.

[0093] [Comparative Example 1] The same procedure as in Example 1 was carried out except that the phytoncide solution was not applied.

[0094] [Comparative Examples 2 and 3] Using the activated carbons prepared in Production Examples 4 and 5 in the same manner as in Example 1, filters equipped with phytoncide-impregnated carbon porous materials of Comparative Examples 2 and 3 were respectively produced. Phytoncide solution was impregnated the same number and amount as in Example 1, and the filters were compressed, squeezed, and re-impregnated. As a result, the weight gains after the impregnation procedure in Comparative Examples 2 and 3 were 0.4 g and 0.5 g, respectively.

[0095] When activated carbon satisfying the requirements of the present invention is used, the amount of phytoncide (essential oil) impregnated per 100 parts by mass of activated carbon is considered to be sufficient to impregnate the activated carbon and achieve its intended effect. Based on the difference in the impregnation amount increment between Example 1 and Comparative Example 2, approximately 1.5 g of phytoncide solution is impregnated into the phytoncide-impregnated carbon porous material of Example 1. Furthermore, considering the cases where the water in the phytoncide solution does not evaporate and where only the water evaporates completely, it is estimated that 0.006 g to 1.5 g of phytoncide is impregnated per 1.08 g of activated carbon in Example 1, or approximately 0.5 to 140 parts by mass of phytoncide impregnated per 100 parts by mass of activated carbon. Similarly, it is estimated that the amount is approximately 0.6 to 220 parts by mass in Example 2 and 0.75 to 250 parts by mass in Example 3. Furthermore, in Comparative Examples 2 and 3, assuming that the entire increase in the filter mass is impregnated into the activated carbon, it is estimated that essential oil is impregnated in the ranges of 0.0011 to 0.37 parts by mass and 0.0014 to 0.46 parts by mass per 100 parts by mass of activated carbon, respectively.

[0096] [Antiviral activity against feline coronavirus] Feline infectious peritonitis virus (FIPV; feline virus: strain 79-1146), frozen and stored in a deep-freeze refrigerator, was used to infect fcwf4 cells (feline kidney cells: strain fcwf4p86) at a multiplicity of infection (MOI) of 0.01 in cell growth medium (Eagle's MEM (Gibco) containing 10% FBS) and cultured for 72 hours at 37°C in the presence of 5% CO2 (passage 1). Five consecutive passages were cultured in large quantities, and the virus solution was separated and purified by sucrose density ultra-high-speed centrifugation. It was then dispensed into 1 mL aliquots and stored in a deep-freeze at -80°C until use in experiments. A portion of the virus solution was used to confirm cytopathic effect using a 10-fold serial dilution method, and viral infectivity (TCID 50 ) was measured.

[0097] <Test Method> Testing performance of special fibers against feline coronavirus Measurement conditions Contact time: 1, 5, 10, 60, 480 minutes Number of specimens: 3 times for each test condition Collection volume: 1 ml / fiber (10 mm x 10 mm)

[0098] <Measurement method> 1. About 10 minutes in advance 7.00 TCID 50 Feline infectious peritonitis virus (FIPV; feline virus: strain 79-1146) was adjusted to a concentration of 0.01 / ml. The optimal virus concentration was calculated based on the cytopathic effect in a virus-free negative control (preliminary test).

[0099] 2. Test pieces (10 mm x 10 mm) cut from the sheets equipped with the essential oil-impregnated carbon porous materials obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were placed in cell culture dishes (60 mm diameter). 100 μL of the virus solution with the adjusted concentration was dropped onto the test pieces. Immediately after dropping, the test pieces were cultured at 37°C in the presence of 5% CO2 for the specified period of time.

[0100] 3. The test piece was collected at each contact time specified in the measurement conditions, and 1 mL of virus maintenance medium Eagle's MEM (Gibco) containing 1% BSA was added to perform a washing operation, and the virus solution was collected.

[0101] 4. The recovered virus solution was diluted 10-fold and inoculated onto fcw-f4 cells in a 96-well microplate for 1 hour of contact infection. After removing the virus solution, 0.1 ml of virus maintenance medium, Eagle's MEM (Gibco) containing 1% BSA, was added and the cells were cultured for 96 hours at 37°C in the presence of 5% CO2. Cytopathic effect (CPE) or metabolic inhibition was observed every 24 hours, and the virus infectious titer (TCID50) was measured. The effective dilution series of the recovered virus solution was calculated based on the cytopathic effect in a control test (preliminary test) that did not contain virus.

[0102] <Preliminary test: Cytotoxicity> Four test substances (each 10mm x 10mm piece) were mixed with 0.1ml of cell growth medium to prepare the measurement sample stock solution, which was diluted 10-fold and then inoculated onto FCW-F4 cells in a 96-well microplate. With the exception of test substance A, 100% cytopathic effect (CPE) was observed in the measurement sample stock solution for the three test substances (Table 3). -1 In the diluted solutions, test substances B, C, and D caused 20% cell degeneration. -2 10% cytopathic change was observed in the diluted solution.

[0103] These results suggest that the test substance affects the fcw-f4 cells used in virus titer measurements, and it was determined that a 1 / 1000 dilution would be appropriate for further testing. Furthermore, it was decided that the infectious titer of FIPV used in the measurements should be equivalent to 7.0 TCID50 / ml or higher. The results are shown in Table 2.

[0104] [Table 2]

[0105] [Antibacterial performance] The antibacterial performance of the filters comprising the essential oil-impregnated carbon porous materials obtained in the above examples and comparative examples was tested with reference to the five test methods in JIS Z 2801:2010 "Antibacterial processed products - Antibacterial test methods and antibacterial effect."

[0106] The filter comprising the essential oil-impregnated carbon porous material was cut into a size of approximately 5 cm x 5 cm, and 0.5 g of the granular material was weighed out so that it could be evenly distributed within an area of ​​approximately 5 cm x 5 cm to prepare a sample.

[0107] Each specimen was inoculated with a test bacterial solution (0.4 mL of Staphylococcus aureus (S. aureus) and 0.4 mL of Escherichia coli (E. coli)), and a covering film (polyethylene film, approximately 4 cm x 4 cm, approximately 0.09 mm thick) was placed on top and tightly attached. The specimen was then stored at 35°C for 24 hours, and the viable bacterial count per sample was measured. Measurements were performed three times.

[0108] The antibacterial activity value R was calculated using the following formula: R=(Ut-U0)-(At-U0)=Ut-At U0: Mean logarithm of the number of viable bacteria ( / unit) immediately after inoculation of the untreated (control) sample pieces Ut: Mean logarithm of the number of viable bacteria ( / unit) on untreated sample pieces after 24 hours At: Mean logarithm of the number of viable bacteria ( / unit) in the antibacterial sample after 24 hours The results are shown in Table 3. The antibacterial activity value R was determined against Staphylococcus aureus and Escherichia coli.

[0109] The index for determining whether the antibacterial property is sufficiently functional was determined to be an inhibitory effect when the antibacterial activity value R was 2.0 or more.

[0110] [Table 3]

[0111] The results in Tables 2 and 3 show that the filters comprising the essential oil-impregnated porous carbon materials obtained in Examples 1 to 3 had sufficient essential oil impregnated therein and had good antiviral and antibacterial properties. In contrast, the essential oil was not impregnated in the porous carbon material of Comparative Example 1, and the filters comprising the essential oil-impregnated porous carbon materials obtained in Comparative Examples 2 and 3 were unable to impregnate the essential oil sufficiently and had poor antiviral and antibacterial properties.

[0112] This application is based on Japanese Patent Application No. 2020-138757, filed on August 19, 2020, the contents of which are incorporated herein by reference.

[0113] In order to express the present invention, the present invention has been properly and sufficiently described above through specific embodiments, but it should be recognized that those skilled in the art can easily change and / or improve the above embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes them to depart from the scope of the claims set forth in the claims, such changes or improvements are construed as being encompassed within the scope of the claims. [Industrial Applicability]

[0114] INDUSTRIAL APPLICABILITY The present invention has wide industrial applicability in air purification technologies, particularly in the technical fields of antiviral agents, antibacterial agents, filters, and the like.

Claims

1. An essential oil-impregnated porous carbon material impregnated with water and an essential oil having at least one of an antibacterial activity and an antiviral activity, wherein the carbon porous material constituting the essential oil-impregnated porous carbon material has a specific surface area of ​​500 m2 as determined by a nitrogen adsorption BET method. ２ / g or more 2500m ２ / g or less, the amount of acidic functional groups is 0.1 meq / g or more and 4 meq / g or less, and the pore volume of pores with a pore diameter of 2 nm or less, obtained by analyzing the adsorption isotherm obtained by measuring the amount of nitrogen adsorption using the NL-DFT method, is 0.35 cm ３ / g or more of the essential oil-impregnated carbon porous material.

2. 2. The essential oil-impregnated carbon porous material according to claim 1, further impregnated with a surfactant.

3. 3. The essential oil-impregnated carbon porous material according to claim 1, wherein the essential oil is a natural extract derived from a plant.

4. 4. The essential oil-impregnated carbon porous material according to claim 1, wherein the content of the metal chloride relative to the carbon porous material is less than 0.1 times by mass.

5. An antibacterial agent comprising the essential oil-impregnated carbon porous material according to any one of claims 1 to 4.

6. An antiviral agent comprising the essential oil-impregnated carbon porous material according to any one of claims 1 to 5.

7. A filter comprising the antibacterial agent according to claim 5.

8. A filter comprising the antiviral agent according to claim 6.

9. An air purifier comprising the filter according to claim 7 or 8.

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