Adsorbent and adsorption filter containing adsorbent

Abstract

Provided is an adsorbent having high removal performance with respect to contaminants such as volatile organic compounds, the adsorbent being capable of forming an adsorption filter that undergoes little pressure loss when the adsorption filter is manufactured using the adsorbent. An adsorbent according to the present disclosure contains an adsorbent A having an average particle major axis of 200-900 μm, an adsorbent B having an average particle major axis of 0.1-100 μm, and a thermoplastic resin C having an average particle major axis of 0.1-100 μm. The adsorbent B is fixed to the surface of the adsorbent A via the thermoplastic resin C.

Description

Adsorbent and adsorption filter containing adsorbent

[0001] SUMMARY The present disclosure relates to adsorbents for removing contaminants and to adsorption filters including the adsorbents.

[0002] In recent years, environmental society has shown growing interest in measures to combat odor pollution. Examples of odor pollution include pollution caused by exhaust gases. Volatile organic compounds, such as toluene and acetaldehyde, are known to be causative agents of sick-house syndrome, and the removal and deodorization of these odorous substances presents a major challenge. It is known that these exhaust gases can be removed using filters attached to air purification devices such as air purifiers and air conditioners. It is preferable for these filters to have low pressure loss, i.e., high breathability.

[0003] There is a strong demand for filters that have high pollutant removal performance and low pressure loss to remove the above-mentioned pollutants. In response to this demand, Patent Document 1 discloses a method for forming irregular aggregates of activated carbon particles of the same particle size using a thermoplastic resin, thereby creating voids between the aggregates and achieving low pressure loss. Patent Document 2 discloses a method for supporting particles with an average particle size of 1 μm or less on a nonwoven fabric, thereby achieving high volatile organic compound removal performance.

[0004] Japanese Patent No. 3612329 Japanese Patent Application Laid-Open No. 2015-157250

[0005] However, the present inventors have found that the filter of Patent Document 1 has problems such as the aggregates collapsing due to the external force applied when forming the adsorbent into a sheet, filling voids and increasing pressure loss, and the irregular structure of the formed aggregates resulting in large variations in performance.Furthermore, the present inventors have found that the filter of Patent Document 2 has a problem in that when the particle diameter of the particles used is small, the adsorbent particles fill the voids between the nonwoven fabric fibers, resulting in high pressure loss.

[0006] In view of the above problems, an object of the present disclosure is to provide an adsorbent that has high performance in removing pollutants such as volatile organic compounds, and that can be used to produce an adsorption filter with low pressure loss.Another object of the present disclosure is to provide an adsorption filter that has high performance in removing pollutants such as volatile organic compounds and low pressure loss.

[0007] The present inventors have conducted extensive research to solve the above problems, and have finally completed the present disclosure. The adsorbent and adsorption filter of the first disclosure are preferably any of the following: 1. An adsorbent comprising: adsorbent A having an average particle length of 200 to 900 μm; adsorbent B having an average particle length of 0.1 to 100 μm; and thermoplastic resin C having an average particle length of 0.1 to 100 μm, wherein adsorbent B is fixed to the surface of adsorbent A via thermoplastic resin C. 2. The adsorbent according to item 1 above, wherein the weight ratio of adsorbent A to adsorbent B is 100:1 to 20. 3. The adsorbent according to item 1 or 2 above, wherein the weight ratio of adsorbent A to thermoplastic resin C is 100:1 to 20. 4. The adsorbent according to any one of items 1 to 3 above, wherein adsorbent A comprises activated carbon, activated alumina, silica gel, zeolite, or a mixture thereof. 5. The adsorbent according to any one of claims 1 to 4 above, wherein the adsorbent B comprises activated carbon, activated alumina, silica gel, zeolite, or a mixture thereof. 6. The adsorbent according to any one of claims 1 to 5 above, wherein the thermoplastic resin C comprises at least one selected from the group consisting of polyolefin resins, polyamide resins, polyester resins, polyacrylic resins, and copolymers thereof. 7. The adsorbent according to any one of claims 1 to 6 above, wherein the adsorbent A comprises activated carbon and the adsorbent B comprises activated carbon. 8. The adsorbent according to any one of claims 1 to 6 above, wherein the adsorbent A comprises activated carbon and the adsorbent B comprises silica gel. 9. The adsorbent according to any one of claims 1 to 8 above, wherein the thermoplastic resin C comprises an ethylene-acrylic acid copolymer resin. 10. An adsorption filter comprising the adsorbent according to any one of claims 1 to 9 above and a substrate.

[0008] The adsorption filter of the second disclosure is preferably any one of the following: 11. An adsorption filter comprising an adsorbent A having an average particle length of 200 to 900 μm, an adsorbent B having an average particle length of 0.1 to 100 μm, a thermoplastic resin C having an average particle length of 0.1 to 100 μm, and a substrate, wherein the adsorbent A, the adsorbent B, and the thermoplastic resin C are supported on the substrate, 500 or more particles of the adsorbent B are fixed to each particle of the adsorbent A via the thermoplastic resin C, and when the total number of the adsorbents B is 100%, 65% or more of the adsorbents B are fixed to the adsorbent A via the thermoplastic resin C. 12. An adsorption filter according to item 11 above, wherein the weight ratio of the adsorbent A to the adsorbent B is 100:1 to 20. 13. An adsorption filter according to item 11 or 12 above, wherein the weight ratio of the adsorbent A to the thermoplastic resin C is 100:1 to 20. 14. The adsorption filter according to any one of claims 11 to 13, wherein the adsorbent A comprises activated carbon, activated alumina, silica gel, zeolite, or a mixture thereof. 15. The adsorption filter according to any one of claims 11 to 14, wherein the adsorbent B comprises activated carbon, activated alumina, silica gel, zeolite, or a mixture thereof. 16. The adsorption filter according to any one of claims 11 to 15, wherein the thermoplastic resin C comprises at least one selected from the group consisting of polyolefin resins, polyamide resins, polyester resins, polyacrylic resins, and copolymers thereof. 17. The adsorption filter according to any one of claims 11 to 16, wherein 500 to 2,000,000 particles of the adsorbent B are fixed to each particle of the adsorbent A via the thermoplastic resin C, and when the total number of the adsorbents B is taken as 100%, 65% to 100% of the adsorbents B are fixed to the adsorbent A via the thermoplastic resin C. 18. 18. The adsorption filter according to any one of claims 11 to 17 above, wherein adsorbent A comprises activated carbon, and adsorbent B comprises activated carbon. 19. The adsorption filter according to any one of claims 11 to 17 above, wherein adsorbent A comprises activated carbon, and adsorbent B comprises silica gel. 20. The adsorption filter according to any one of claims 11 to 19 above, wherein thermoplastic resin C comprises an ethylene acrylic acid copolymer resin.

[0009] The contents of the first disclosure and the contents of the second disclosure may be combined.

[0010] The adsorbent of the first disclosure has adsorbent B, which has a small average particle length of 0.1 μm to 100 μm, fixed to adsorbent A via thermoplastic resin C. This increases the surface area for adsorbing pollutants, thereby increasing the pollutant removal rate. The first disclosure can provide an adsorbent and an adsorption filter that can improve the removal performance of pollutants such as volatile organic compounds and reduce pressure loss when an adsorption filter is produced.

[0011] The adsorption filter of the second disclosure has adsorbent B, which has a small average particle length of 0.1 μm to 100 μm, fixed to adsorbent A via thermoplastic resin C on a substrate. This increases the surface area for adsorbing contaminants, thereby increasing the contaminant removal rate. Furthermore, since at least 65% of the total number of adsorbents B is fixed to the surface of adsorbent A, there is little adsorbent B free from the surface of adsorbent A, preventing clogging caused by adsorbent B filling gaps in the substrate. This makes it possible to manufacture an adsorption filter with low pressure loss. The adsorption filter of the second disclosure thus increases the removal rate of contaminants, including volatile organic compounds, while also reducing pressure loss, thereby improving contaminant removal performance.

[0012] 1 is a scanning electron microscope photograph of the adsorbent obtained in Example 2A of the second disclosure. 2 is a scanning electron microscope photograph of the adsorption filter obtained in Example 2A of the second disclosure, after the substrate has been peeled off. 3 is a scanning electron microscope photograph of the adsorption filter obtained in Comparative Example 2A of the second disclosure, after the substrate has been peeled off.

[0013] While the embodiments of the present disclosure will be described below, the present disclosure is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the above and below-described aims, all of which are encompassed within the technical scope of the present disclosure. The following description will be given in the order of the first disclosure and the second disclosure.

[0014] <First Disclosure> An adsorbent according to an embodiment of the first disclosure includes adsorbent A having an average particle length of 200 μm to 900 μm, adsorbent B having an average particle length of 0.1 to 100 μm, and thermoplastic resin C having an average particle length of 0.1 to 100 μm, wherein adsorbent B is fixed to adsorbent A via thermoplastic resin C. The adsorbent according to the embodiment of the first disclosure will be hereinafter referred to as "adsorbent D" to avoid confusion with adsorbent A and adsorbent B.

[0015] The mechanism of improved volatile organic compound removal performance according to the first disclosure is presumed to be as follows. Adsorption occurs at the interface between the gas, liquid, or solid phase and the adsorbent. Therefore, by increasing the contact probability at the interface between the adsorbent and the adsorbed substance, the adsorbed substance can be adsorbed to the adsorbent with high efficiency. Adsorbent D according to the embodiment of the first disclosure contains adsorbent B, which has a small average particle length of 0.1 μm to 100 μm, resulting in a large surface area per unit volume and a high removal rate of pollutants. Furthermore, when an adsorption filter is manufactured using adsorbent D, if the particles contained in adsorbent D have small particle sizes, voids are filled, resulting in a high packing density and, as a result, high pressure loss. However, in adsorbent D according to the embodiment of the first disclosure, adsorbent B, which has a small average particle length, is fixed to the surface of adsorbent A, which has a large average particle length of 200 μm to 900 μm, via thermoplastic resin C. As a result, when an adsorption filter is produced using the adsorbent D, voids are easily formed between the particles, so the packing density does not become too high, and an adsorption filter with low pressure loss can be produced.

[0016] When producing adsorbent D, adsorbent A having an average particle length of 200 to 900 μm and adsorbent B having an average particle length of 0.1 to 100 μm can be obtained by sieving the adsorbent particles through a mesh. The mesh size can be selected depending on the desired particle length. For example, adsorbent A having a large average particle length can be obtained by sieving particles that can pass through a No. 18 mesh but not through a No. 65 mesh or larger mesh. Adsorbent B having a small average particle length can be obtained by sieving through a No. 200 mesh or larger mesh. These mesh numbers refer to the number of meshes per inch (25.4 mm).

[0017] After being manufactured as adsorbent D, the major axes of adsorbent A, adsorbent B, and thermoplastic resin C contained in adsorbent D can be measured from a micrograph such as a scanning electron microscope (SEM). The major axes of adsorbent A, adsorbent B, and thermoplastic resin C can be determined, for example, by observing 100 particles of each of adsorbent A, adsorbent B, and thermoplastic resin C using an SEM, measuring the length of the longest line segment connecting two points on the outer edge of a particle, and averaging the 100 measurements. In the micrograph, if the particle shape is circular, the length of the line segment is the diameter of the circle; if the particle shape is elliptical, the length of the line segment is the major axis of the ellipse; and if the particle shape is rectangular, the length of the line segment is the diagonal length of the rectangle. However, the shape of the particle is not limited to the above shapes. Regardless of the shape of the particle, the major axis can be uniquely determined by the above definition.

[0018] The average particle length of adsorbent A is preferably 200 to 900 μm, more preferably 300 to 850 μm. It is even more preferably 350 to 800 μm, and most preferably 400 to 750 μm. This range has the advantage that pressure loss does not increase significantly and production into a sheet is easy. If the average particle length is 200 μm or more, pressure loss does not increase when an adsorption filter is produced using adsorbent D. Furthermore, if the average particle length is 900 μm or less, the thickness of the adsorption filter does not increase, and production of the adsorption filter is not difficult.

[0019] The average particle length of adsorbent B is preferably 0.1 to 100 μm, more preferably 0.5 to 75 μm. It is even more preferably 1 to 50 μm, and most preferably 5 to 30 μm. Within this range, adsorbent B can be uniformly fixed to the surface of adsorbent A. If the average particle length of adsorbent B is 0.1 μm or more, the cohesive force of adsorbent B does not increase, and adsorbent B can be easily and uniformly fixed to the surface of adsorbent A. If the average particle length of adsorbent B is 100 μm or less, the adsorbent B does not become too large relative to the surface area of ​​adsorbent A, making it easier to ensure the adhesion force of adsorbent B to the surface of adsorbent A and preventing adsorbent B from falling off adsorbent A. This avoids difficulties in production.

[0020] The average particle length of the thermoplastic resin C is preferably 0.1 to 100 μm, more preferably 0.5 to 75 μm. It is even more preferably 1 to 50 μm, and most preferably 5 to 30 μm. Within this range, it is possible to uniformly adhere adsorbent B to the surface of adsorbent A. If the average particle length of the thermoplastic resin C is 0.1 μm or more, the cohesive force of the thermoplastic resin C is not increased, and the thermoplastic resin C can be easily and uniformly adhered to the surface of adsorbent A. If the average particle length of the thermoplastic resin C is 100 μm or less, the size of the thermoplastic resin C does not become too large, and the force for adhering adsorbent B is sufficient, preventing adsorbent B from falling off adsorbent A. Therefore, manufacturing is not difficult.

[0021] The weight ratio of adsorbent A to adsorbent B is preferably 100:1 to 20, more preferably 100:2 to 18, and most preferably 100:4 to 15. Within this range, adsorbent B can be uniformly fixed to the surface of adsorbent A. When the weight ratio of adsorbent A to adsorbent B is 100:1 or more, the effects of adsorbent B used are more easily obtained. Furthermore, when the weight ratio of adsorbent A to adsorbent B is 100:20 or less, a sufficient amount of adsorbent B can be fixed to adsorbent A, while the pressure loss of the adsorption filter can be suppressed when the adsorption filter is manufactured.

[0022] The weight ratio of adsorbent A to thermoplastic resin C is preferably 100:1 to 20, more preferably 100:2 to 18, and most preferably 100:4 to 15. Within this range, thermoplastic resin C can be uniformly attached to the surface of adsorbent A.

[0023] Adsorbent A and adsorbent B are preferably made of a material intended to capture ions or molecules contained in the gas phase, such as contaminants such as toluene or acetaldehyde, and thereby remove them from the target gas phase.

[0024] The adsorbent A may be any of the above materials, but examples thereof include activated carbon, activated alumina, silica gel, and zeolite. These may be selected depending on the intended use. One of these may be used alone, or two or more may be used in combination. To remove volatile organic compounds such as toluene and acetaldehyde, the adsorbent A preferably contains activated carbon, silica gel, or a mixture thereof.

[0025] The adsorbent B may be any of the above materials, but examples thereof include activated carbon, activated alumina, silica gel, and zeolite. These may be selected depending on the intended use. One of these may be used alone, or two or more may be used in combination. To remove volatile organic compounds such as toluene and acetaldehyde, it is preferable that the adsorbent B contains activated carbon, silica gel, or a mixture thereof.

[0026] The activated carbon is not particularly limited, but it is preferable to use common activated carbon such as coconut shell activated carbon, coal-based activated carbon, wood-based activated carbon, and synthetic resin-based activated carbon in terms of performance and availability.

[0027] The BET surface area of ​​the activated carbon is not particularly limited, but is preferably 800 to 1500 m ２ / g is preferred, and 850 to 1300m ２ / g is more preferable in terms of performance. ２ / g or more, the deodorizing effect is easily obtained. ２ / g or less, it is possible to prevent contaminants that have been adsorbed from being desorbed.

[0028] The pore volume of the activated carbon is not particularly limited, but is preferably 0.30 to 0.70 cm ３ / g, and 0.40 to 0.55 cm ３ / g. ３ / g or more, the deodorizing effect is easily obtained. ３ / g or less, it is possible to prevent contaminants that have been adsorbed from being desorbed.

[0029] The average pore size of the activated carbon can be adjusted appropriately depending on the substance to be adsorbed. For example, when the substance to be adsorbed is toluene, the average pore size is preferably 15 Å to 19 Å, more preferably 16 Å to 18 Å, but is not particularly limited.

[0030] The BET specific surface area of ​​the silica gel is not particularly limited, but is preferably 20 to 1000 m ２ / g is preferred, and 50 to 700m ２ / g is preferable in terms of performance. ２ / g or more, the deodorizing effect is easily obtained. ２ / g or less, it is possible to prevent contaminants that have been adsorbed from being desorbed.

[0031] The adsorbent A, the adsorbent B, or the adsorbent D may be subjected to a chemical treatment before use in order to improve the adsorption performance of polar substances and aldehydes. Suitable chemicals used in gas chemical treatment include, for example, amine-based chemicals such as ethanolamine, polyethyleneimine, aniline, p-anisidine, and sulfanilic acid, as well as sodium hydroxide, potassium hydroxide, guanidine carbonate, guanidine phosphate, aminoguanidine sulfate, 5,5-dimethylhydantoin, benzoguanamine, 2,2-iminodiethanol, 2,2,2-nitrotriethanol, ethanolamine hydrochloride, 2-aminoethanol, 2,2-iminodiethanol hydrochloride, p-aminobenzoic acid, sodium sulfanilate, L-arginine, methylamine hydrochloride, semicarbazide hydrochloride, hydrazine, hydroquinone, hydroxylamine sulfate, permanganate, potassium carbonate, and potassium bicarbonate for aldehyde gases, nitrogen compounds such as NOx, sulfur compounds such as SOx, and acidic polar substances such as acetic acid. These may be used alone or in combination. For basic polar substances such as ammonia, methylamine, trimethylamine, and pyridine, for example, phosphoric acid, citric acid, malic acid, ascorbic acid, and tartaric acid are preferably used. The chemical treatment is carried out, for example, by supporting or impregnating the chemical on the adsorbent A, adsorbent B, or adsorbent D.

[0032] The thermoplastic resin C is a material that softens when heated, can be molded or processed, and solidifies when cooled. The thermoplastic resin C is not limited to any particular material, but examples include polyolefin resins, polyamide resins, polyester resins, polyacrylic resins, and copolymers thereof. These may be used alone or in combination of two or more. Examples of copolymers include copolymers having at least a structural unit derived from a first monomer and a structural unit derived from a second monomer. The first monomer and the second monomer may be the same as the monomers used to produce the polyolefin resin, polyamide resin, polyester resin, or polyacrylic resin, respectively. For example, the copolymer may include an ethylene-acrylic acid copolymer resin having ethylene units derived from ethylene and acrylic acid units derived from acrylic acid. To produce such an ethylene-acrylic acid copolymer resin, it is not necessary to react the polyolefin resin with the polyacrylic resin; instead, the resin may be produced by copolymerizing ethylene, acrylic acid, and, if necessary, other monomers.

[0033] Although not particularly limited, the melt index value of thermoplastic resin C is preferably 50 g / 10 min or less, and more preferably 30 g / 10 min or less. A melt index value of 50 g / 10 min or less can prevent the thermoplastic resin C from covering the pores of adsorbent A and adsorbent B during processing, thereby preventing a decrease in deodorizing performance.

[0034] The method for producing adsorbent D is not particularly limited, but examples thereof include a method in which adsorbent A and thermoplastic resin C are mixed, and then adsorbent B is added and the mixture is heated and stirred, and a method in which adsorbent A, adsorbent B, and thermoplastic resin C are simultaneously heated and stirred.

[0035] The adsorbent D is preferably one that removes ions or molecules contained in a gas phase, such as toluene or acetaldehyde, from the target gas phase by capturing them therein, but it can be used for a variety of purposes, including, but not limited to, an adsorption filter attached to an air purification device such as an air purifier or air conditioner.

[0036] The adsorption filter comprises an adsorbent D and a substrate. The substrate can be obtained by molding a filter material. The molding method is not particularly limited, but methods of processing the filter material into a flat, pleated, or honeycomb shape are preferred. When used as a cross-flow filter, the pleated shape increases the contact area with the gas to be treated, improving the removal rate of pollutants and simultaneously reducing the pressure loss of the filter.

[0037] The substrate is a sheet containing adsorbent D. The sheet processing method is not particularly limited, and conventionally known processing methods can be used. For example, (a) a wet sheeting method in which adsorbent D is dispersed in water together with sheet-constituting fibers and dehydrated, (b) an airlaid method in which an adsorbent is dispersed in air together with sheet-constituting fibers, (c) a method in which an adsorbent is filled between two or more layers of nonwoven fabric, woven fabric, net-like material, film, or membrane substrate by thermal bonding, (d) a method in which an adsorbent is bonded to a breathable material such as a nonwoven fabric, woven fabric, or urethane foam using an emulsion adhesive or a solvent-based adhesive, (e) a method in which an adsorbent is supported on a breathable material such as a nonwoven fabric, woven fabric, or urethane foam by utilizing the thermoplasticity of the substrate or thermoplastic resin, or (f) a method in which the adsorbent is mixed and integrated by kneading it into fibers or resin. In particular, the methods (b), (c), and (e) are preferably used because they do not require the use of a surfactant and can prevent the adsorbent from being coated. The substrate described in the second disclosure may be used as the substrate in the first disclosure.

[0038] The adsorbent D according to the embodiment of the first disclosure and the adsorption filter manufactured using it are preferably used for the purpose of removing volatile organic compounds, such as toluene and aldehydes, indoors, in vehicles, wallpaper, furniture, interior materials, resin molded bodies, electrical equipment, etc. For example, it is preferable to fill the granular material in a breathable container such as a box, bag, or net, and leave it to stand or allow it to ventilate before use.

[0039] <Second Disclosure> An adsorption filter according to an embodiment of the second disclosure comprises an adsorbent A having an average particle length of 200 μm to 900 μm, an adsorbent B having an average particle length of 0.1 μm to 100 μm, a thermoplastic resin C having an average particle length of 0.1 to 100 μm, and a substrate, wherein the adsorbent A, the adsorbent B, and the thermoplastic resin C are supported on the substrate, 500 or more particles of the adsorbent B are fixed to each particle of the adsorbent A via the thermoplastic resin C, and when the total number of the adsorbents B is taken as 100%, 65% or more of the adsorbents B are fixed to the adsorbent A via the thermoplastic resin C.

[0040] The mechanism of improved volatile organic compound removal performance according to the second disclosure is presumed to be as follows. Adsorption occurs at the interface between the gas, liquid, or solid phase and the adsorbent. Therefore, by increasing the contact probability at the interface between the adsorbent and the adsorbed substance, the adsorbed substance can be adsorbed to the adsorbent with high efficiency. The adsorption filter according to the second disclosure includes adsorbent B, which has a small average particle length of 0.1 μm to 100 μm, resulting in a large surface area per unit volume of the entire adsorbent, thereby achieving a high contaminant removal rate. Furthermore, if the adsorbent particle size is small, voids are filled, resulting in a high packing density and therefore high pressure loss. However, in the adsorption filter according to the second disclosure, 500 or more particles of adsorbent B, which has a small average particle length, are fixed to the surface of adsorbent A, which has a large average particle length of 200 μm to 900 μm, via thermoplastic resin C, which has an average particle length of 0.1 to 100 μm. This facilitates the formation of voids between the adsorbent particles in the adsorption filter, preventing excessive packing density. Furthermore, in the adsorption filter according to the embodiment of the second disclosure, 65% or more of the total 100% of the adsorbents B are fixed to the surface of the adsorbent A via the thermoplastic resin C, so that there is little adsorbent B remaining free from the surface of the adsorbent A, and it is possible to prevent adsorbent B from filling up and clogging gaps in the substrate. As a result, an adsorption filter with low pressure loss can be obtained. When the adsorption filter according to the embodiment of the second disclosure is attached to and used in an air purification device such as an air purifier or air conditioner, the differential pressure between the upstream and downstream sides of the adsorption filter is reduced, improving adsorption performance and contributing to energy savings.

[0041] When manufacturing an adsorption filter, adsorbent A with an average particle length of 200 to 900 μm and adsorbent B with an average particle length of 0.1 to 100 μm can be obtained by sieving adsorbent particles through a mesh. Adsorbent A with a large average particle length can be obtained by, for example, sieving particles that can pass through a No. 18 mesh but not through a No. 65 mesh or larger mesh, while adsorbent B with a small average particle length can be obtained by, for example, sieving through a No. 200 mesh or larger mesh. The mesh numbers are the number of meshes per inch (25.4 mm). The mesh numbers can be selected based on the desired particle length.

[0042] After the adsorption filter is manufactured, the major axes of the adsorbent A, adsorbent B, and thermoplastic resin C contained in the adsorption filter can be measured from a photograph obtained by removing at least a portion of the substrate so that the adsorbent A, adsorbent B, and thermoplastic resin C can be observed, and then observing the adsorbent A, adsorbent B, and thermoplastic resin C with a microscope such as a scanning electron microscope (SEM). The major axes of the adsorbent A, adsorbent B, and thermoplastic resin C can be determined, for example, by observing 100 particles of each adsorbent A, adsorbent B, and thermoplastic resin C with an SEM, measuring the length of the longest line segment connecting two points on the outer edge of a particle, and averaging the 100 measurements. In the micrograph, if the particle shape is circular, the length of the line segment is the diameter of the outer edge; if the particle shape is elliptical, the length of the line segment is the major axis of the ellipse; and if the particle shape is rectangular, the length of the line segment is the diagonal length of the rectangle. However, the shape of the particle is not limited to the above shapes. Regardless of the shape of the particle, the major axis can be uniquely determined by the above definition.

[0043] The average particle length of adsorbent A is preferably 200 to 900 μm, more preferably 300 to 850 μm. It is even more preferably 350 to 800 μm, and most preferably 400 to 750 μm. This range has the advantage that pressure loss does not increase significantly and the adsorption sheet is easy to manufacture. If the average particle length is 200 μm or more, the pressure loss does not increase when an adsorption filter is manufactured. Furthermore, if the average particle length is 900 μm or less, the thickness of the adsorption filter does not increase, and manufacturing the adsorption filter is not difficult.

[0044] The average particle length of adsorbent B is preferably 0.1 to 100 μm, more preferably 0.5 to 75 μm. It is even more preferably 1 to 50 μm, and most preferably 5 to 30 μm. Within this range, adsorbent B can be uniformly fixed to the surface of adsorbent A. If the average particle length of adsorbent B is 0.1 μm or more, the cohesive force of adsorbent B does not increase, and adsorbent B can be easily and uniformly fixed to the surface of adsorbent A. If the average particle length of adsorbent B is 100 μm or less, the adsorbent B does not become too large relative to the surface area of ​​adsorbent A, making it easier to ensure the adhesion force of adsorbent B to the surface of adsorbent A and preventing adsorbent B from falling off adsorbent A. This avoids difficulties in production.

[0045] The average particle length of the thermoplastic resin C is preferably 0.1 to 100 μm, more preferably 0.5 to 75 μm. It is even more preferably 1 to 50 μm, and most preferably 5 to 30 μm. Within this range, it is possible to uniformly adhere adsorbent B to the surface of adsorbent A. If the average particle length of the thermoplastic resin C is 0.1 μm or more, the cohesive force of the thermoplastic resin C is not increased, and the thermoplastic resin C can be easily and uniformly adhered to the surface of adsorbent A. If the average particle length of the thermoplastic resin C is 100 μm or less, the size of the thermoplastic resin C does not become too large, and the force for adhering adsorbent B is sufficient, preventing adsorbent B from falling off adsorbent A. Therefore, manufacturing is not difficult.

[0046] The number of adsorbents B fixed per particle of adsorbent A is 500 or more, preferably 600 or more, more preferably 800 or more, and even more preferably 1000 or more. If the lower limit of the number of adsorbents B fixed per particle of adsorbent A is within the above range, the surface area for adsorbing contaminants by adsorbent B can be increased, thereby increasing the contaminant removal rate. There is no particular upper limit on the number of adsorbents B fixed per particle of adsorbent A, but for example, it is preferably 2,000,000 or less, more preferably 1,000,000 or less, even more preferably 500,000 or less, and particularly preferably 100,000 or less. The number of adsorbents B that can adhere to the surface of adsorbent A depends on the size of adsorbents B relative to the surface area of ​​adsorbent A. However, if the upper limit of the number of adsorbents B that can adhere to each particle of adsorbent A is within the above range, adsorbents B are less likely to fall off the surface of adsorbent A, and clogging due to fallen adsorbents can be prevented, thereby reducing the pressure loss of the adsorption filter.

[0047] The number of adsorbents B adhering to each particle of adsorbent A can be obtained from a micrograph taken with a scanning electron microscope (SEM) or the like. The number of adsorbents B adhering to each particle of adsorbent A can be obtained, for example, by removing at least a portion of the substrate so that adsorbents A and B can be observed, observing 10 adsorbent particles with an SEM, counting the number of adsorbents B adhering to the surface of adsorbent A in each case, and then doubling this number assuming that the same number of adsorbents B are adhering to the surface opposite the observation surface, and then averaging the resulting 10 measured values.

[0048] In the adsorption filter, when the total number of adsorbents B is 100%, the number of adsorbents B adhering to the surface of adsorbent A is preferably 65% ​​or more. Adsorbents B that are not adhering to the surface of adsorbent A may fill the voids in the substrate, increasing the pressure loss of the adsorption filter. However, by having the number of adsorbents B adhering to the surface of adsorbent A be 65% or more out of the total number of adsorbents B (100%), the number of adsorbents B that are not adhering to the surface of adsorbent A and are free to fill the voids in the substrate is reduced, thereby reducing the pressure loss of the adsorption filter. The proportion of adsorbents B adhering to the surface of adsorbent A is more preferably 70% or more, even more preferably 75% or more, even more preferably 80% or more, and particularly preferably 90% or more. If the lower limit of the proportion of adsorbents B adhering to the surface of adsorbent A is within the above range, the pressure loss of the adsorption filter can be reduced. The proportion of adsorbent B adhering to the surface of adsorbent A is ideally 100%, but in reality it may be 99% or less, 98% or less, 96% or less, or 95% or less.

[0049] The proportion of adsorbent B adhering to the surface of adsorbent A can be obtained from a micrograph taken with a scanning electron microscope (SEM) or the like. The proportion of adsorbent B adhering to the surface of adsorbent A can be determined, for example, by removing at least a portion of the substrate so that adsorbent A and adsorbent B can be observed, observing with an SEM so that at least 10 adsorbents A fit into one field of view, and counting the number of adsorbents B adhering to the surface of adsorbent A and the number of adsorbents B not adhering to the surface of adsorbent A but present in the gaps between adsorbents A in the field of view. The measurement may be performed by actually counting the number of adsorbents B, or by visually estimating the number of adsorbents B adhering to the surface of adsorbent A and the number of adsorbents B not adhering to the surface of adsorbent A but present in the gaps between adsorbents A.

[0050] The weight ratio of adsorbent A to adsorbent B is preferably 100:1 to 20, more preferably 100:2 to 18, and most preferably 100:4 to 15. Within this range, adsorbent B can be uniformly fixed to the surface of adsorbent A. When the weight ratio of adsorbent A to adsorbent B is 100:1 or more, the effects of adsorbent B used are more easily obtained. Furthermore, when the weight ratio of adsorbent A to adsorbent B is 100:20 or less, the pressure loss of the adsorption filter can be suppressed while a sufficient amount of adsorbent B is fixed to adsorbent A.

[0051] The weight ratio of adsorbent A to thermoplastic resin C is preferably 100:1 to 20, more preferably 100:2 to 18, and most preferably 100:4 to 15. Within this range, thermoplastic resin C can be uniformly attached to the surface of adsorbent A.

[0052] Adsorbent A and adsorbent B are preferably made of a material that removes ions or molecules contained in the gas phase, such as contaminants such as toluene or acetaldehyde, from the target gas phase by capturing them therein.

[0053] The adsorbent A may be any of the above materials, but examples thereof include activated carbon, activated alumina, silica gel, and zeolite. These may be selected depending on the intended use. One of these may be used alone, or two or more may be used in combination. To remove volatile organic compounds such as toluene and acetaldehyde, the adsorbent A preferably contains activated carbon, silica gel, or a mixture thereof.

[0054] The adsorbent B may be any of the above materials, but examples thereof include activated carbon, activated alumina, silica gel, and zeolite. These may be selected depending on the intended use. One of these may be used alone, or two or more may be used in combination. To remove volatile organic compounds such as toluene and acetaldehyde, it is preferable that the adsorbent B contains activated carbon, silica gel, or a mixture thereof.

[0055] The activated carbon is not particularly limited, but it is preferable to use common activated carbon such as coconut shell activated carbon, coal-based activated carbon, wood-based activated carbon, and synthetic resin-based activated carbon in terms of performance and availability.

[0056] The BET surface area of ​​the activated carbon is not particularly limited, but is preferably 800 to 1500 m ２ / g is preferred, and 850 to 1300m ２ / g is more preferable in terms of performance. ２ / g or more, the deodorizing effect is easily obtained. ２ / g or less, it is possible to prevent contaminants that have been adsorbed from being desorbed.

[0057] The pore volume of the activated carbon is not particularly limited, but is preferably 0.30 to 0.70 cm ３ / g, and 0.40 to 0.55 cm ３ / g. ３ / g or more, the deodorizing effect is easily obtained. ３ / g or less, it is possible to prevent contaminants that have been adsorbed from being desorbed.

[0058] The average pore size of the activated carbon can be adjusted appropriately depending on the substance to be adsorbed. For example, when the substance to be adsorbed is toluene, the average pore size is preferably 15 Å to 19 Å, more preferably 16 Å to 18 Å, but is not particularly limited.

[0059] The BET specific surface area of ​​the silica gel is not particularly limited, but is preferably 20 to 1000 m ２ / g is preferred, and 50 to 700m ２ / g is preferable in terms of performance. ２ / g or more, the deodorizing effect is easily obtained. ２ / g or less, it is possible to prevent contaminants that have been adsorbed from being desorbed.

[0060] The adsorbent A and / or the adsorbent B may be subjected to a chemical treatment before use in order to improve the adsorption performance of polar substances and aldehydes. Examples of chemicals used in gas chemical treatment include amine-based chemicals such as ethanolamine, polyethyleneimine, aniline, p-anisidine, and sulfanilic acid, as well as sodium hydroxide, potassium hydroxide, guanidine carbonate, guanidine phosphate, aminoguanidine sulfate, 5,5-dimethylhydantoin, benzoguanamine, 2,2-iminodiethanol, 2,2,2-nitrotriethanol, ethanolamine hydrochloride, 2-aminoethanol, 2,2-iminodiethanol hydrochloride, p-aminobenzoic acid, sodium sulfanilate, L-arginine, methylamine hydrochloride, semicarbazide hydrochloride, hydrazine, hydroquinone, hydroxylamine sulfate, permanganate, potassium carbonate, and potassium bicarbonate. These may be used singly or in combination of two or more. For basic polar substances such as ammonia, methylamine, trimethylamine, and pyridine, for example, phosphoric acid, citric acid, malic acid, ascorbic acid, and tartaric acid are preferably used. The chemical treatment is carried out, for example, by supporting or impregnating the chemical on the adsorbent A and / or the adsorbent B.

[0061] The thermoplastic resin C is a material that softens when heated, can be molded or processed, and solidifies when cooled. The thermoplastic resin C is not limited to any particular material, but examples include polyolefin resins, polyamide resins, polyester resins, polyacrylic resins, and copolymers thereof. These may be used alone or in combination of two or more. Examples of copolymers include copolymers having at least a structural unit derived from a first monomer and a structural unit derived from a second monomer. The first monomer and the second monomer may be the same as the monomers used to produce the polyolefin resin, polyamide resin, polyester resin, or polyacrylic resin, respectively. For example, the copolymer may include an ethylene-acrylic acid copolymer resin having ethylene units derived from ethylene and acrylic acid units derived from acrylic acid. To produce such an ethylene-acrylic acid copolymer resin, it is not necessary to react the polyolefin resin with the polyacrylic resin; instead, the resin may be produced by copolymerizing ethylene, acrylic acid, and, if necessary, other monomers.

[0062] Although there are no particular limitations on the melt index value of thermoplastic resin C, it is preferably 50 g / 10 min or less, and more preferably 30 g / 10 min or less. If the melt index value is 50 g / 10 min or less, it is possible to prevent the thermoplastic resin C from covering the pores of adsorbent A and adsorbent B during processing, which would result in a decrease in deodorizing performance.

[0063] The method for fixing adsorbent B to adsorbent A is not particularly limited, but examples include a method in which adsorbent A and thermoplastic resin C are mixed, and then adsorbent B is added, followed by heating and stirring, or a method in which adsorbent A, adsorbent B, and thermoplastic resin C are simultaneously heated and stirred.

[0064] The adsorption filter can be obtained by supporting adsorbent A and adsorbent B on a substrate. The substrate is preferably one that can be molded into a planar, pleated, or honeycomb shape. When used as a cross-flow filter, the pleated shape increases the contact area with the gas to be treated, improving the pollutant removal rate and simultaneously reducing the pressure loss of the filter.

[0065] The method for supporting adsorbent A and adsorbent B on a substrate is not particularly limited, and known processing methods can be used. For example, (a) a wet sheeting method in which adsorbent A and adsorbent B are dispersed in water together with the fibers constituting the substrate and dehydrated, (b) an airlaid method in which adsorbent A and adsorbent B are dispersed in air together with the fibers constituting the substrate, (c) a method in which adsorbent A and adsorbent B are filled between two or more layers of nonwoven fabric, woven fabric, net-like material, film, membrane, etc. by thermal adhesion, (d) a method in which adsorbent A and adsorbent B are bonded and supported on breathable materials such as nonwoven fabric, woven fabric, and urethane foam using an emulsion adhesive or a solvent-based adhesive, (e) a method in which adsorbent A and adsorbent B are bonded and supported on breathable materials such as nonwoven fabric, woven fabric, and urethane foam using the thermoplasticity of a thermoplastic resin, and (f) a method in which adsorbent A and adsorbent B are mixed and integrated by kneading them into fibers or a resin, or other suitable methods can be used depending on the application. In particular, it is preferable to use the above methods (b), (c) and (e) because they do not require the use of a surfactant and can prevent the adsorbent from being coated with the surfactant.

[0066] When adsorbent A and adsorbent B are supported on a substrate, it is preferable to support adsorbent A, with adsorbent B fixed to the surface via thermoplastic resin C, on the substrate. That is, in the above methods (a) to (f), "adsorbent A and adsorbent B" can be read as "adsorbent A, with adsorbent B fixed to the surface via thermoplastic resin C." This makes it possible to easily fix adsorbent B to the surface of adsorbent A.

[0067] The substrate is preferably a nonwoven fabric. The type of nonwoven fabric is not particularly limited, but is preferably a needle-punched nonwoven fabric that can be formed by piercing the fibers with needles having protrusions (needles) to entangle the fibers, a spunlace nonwoven fabric that can be formed by entangling fibers with a high-pressure water jet, a spunbond nonwoven fabric that can be formed by bonding a web formed from long fibers into a sheet, or a laminate thereof. When stacking nonwoven fabrics, it is preferable to bond each layer using, for example, needles. The substrate may also be an electret nonwoven fabric obtained by electrically charging a nonwoven fabric. Needless to say, the substrate may be a material other than a nonwoven fabric, or the nonwoven fabric substrate may contain another material such as a knitted fabric or a woven fabric.

[0068] Adsorption filters can capture ions and molecules contained in a gas phase, such as toluene and acetaldehyde, and remove them from the target gas phase, and can be used for a variety of purposes. Although not particularly limited, adsorption filters can be used indoors, in vehicles, etc., and are preferably used in wallpaper, furniture, interior materials, resin molded articles, electrical equipment, etc.

[0069] This application claims the benefit of priority based on Japanese Patent Application No. 2024-105606 filed on June 28, 2024, and the benefit of priority based on Japanese Patent Application No. 2024-105607 filed on June 28, 2024. The entire contents of the specifications of Japanese Patent Application No. 2024-105606 and Japanese Patent Application No. 2024-105607 are incorporated herein by reference.

[0070] The following examples will specifically demonstrate the effects of the present disclosure. The following examples are not intended to limit the present disclosure, and any design modifications made in accordance with the above and below principles are within the technical scope of the present disclosure. The following will be described in the order of the first disclosure and the second disclosure.

[0071] <First Disclosure> Regarding the first disclosure, first, the measurement method for each performance will be described.

[0072] (Toluene removal performance) Filtration area 36 cm ２A sheet of adsorbent was sandwiched between two columns. Air with a toluene vapor concentration of 80 ppm was supplied to the column at a surface velocity of 20 cm / s, a temperature of 25°C, and a humidity of 50% RH. The toluene concentration at the column outlet was measured every minute, and the removal rate (η) expressed by the following formula was calculated by substituting the toluene inlet concentration (Ci [ppm]) and the toluene outlet concentration (Co [ppm]) into the formula. The toluene concentration was measured using a hydrocarbon meter. Removal rate η (%) = [1 - (Co / Ci)] x 100. The removal rate one minute after the start of measurement was defined as the initial toluene efficiency. Measurement was continued until the removal rate reached 5% or less. The toluene adsorption amount every five minutes was calculated from the removal rate calculated from the toluene concentration at the column outlet measured every five minutes, the toluene concentration at the column inlet, and the air volume. These values ​​were integrated and divided by the filtration area of ​​the sheet of adsorbent packed in the column to obtain the toluene adsorption capacity.

[0073] (Acetaldehyde removal performance) Filtration area 36 cm ２ The adsorbent sheet was sandwiched between two columns. Air with an acetaldehyde vapor concentration of 3 ppm was supplied to the column under conditions of a surface velocity of 20 cm / s, a temperature of 25°C, and a humidity of 50% RH. The acetaldehyde concentration at the column outlet was measured every 5 minutes, and the removal rate (η) expressed by the following formula was calculated by substituting the acetaldehyde inlet concentration (Ci [ppm]) and the acetaldehyde outlet concentration (Co [ppm]) into the following formula. The acetaldehyde concentration was measured using a gas chromatograph equipped with an FID (flame ionization detector). Removal rate η (%) = [1 - (Co / Ci)] x 100

[0074] The removal rate one minute after the start of measurement was defined as the initial acetaldehyde efficiency. Measurement was continued until the removal rate reached 5% or less, and the removal rate was calculated from the acetaldehyde concentration at the column outlet measured every five minutes, and the acetaldehyde concentration at the column inlet and the air volume were used to determine the acetaldehyde adsorption amount every five minutes. These values ​​were integrated and divided by the filtration area of ​​the sheet adsorbent packed in the column to determine the acetaldehyde adsorption capacity.

[0075] (Filtration Performance) The pressure loss PD (mmaq) was determined by placing a sample of the adsorption filter in a duct, controlling the linear velocity through the filter to 10.4 cm / sec, and reading the static pressure difference between upstream and downstream of the sheet with a pressure gauge.

[0076] Example 1: Granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) was used as adsorbent A. ２ / g, pore volume 0.46 cm ３ The thermoplastic resin C was adhered to the surface of the adsorbent A by mixing and stirring an ethylene acrylic acid copolymer resin (average particle length 10 μm, melt index value 9 g / 10 min) as the thermoplastic resin C at a weight ratio of 20:1. Next, powdered activated carbon (average particle length 10 μm, specific surface area 1100 m) as the adsorbent B was added. ２ / g, pore volume 0.52 cm ３ The same amount of thermoplastic resin C (1 / g, average pore diameter 18 Å) was weighed out and heated and stirred at 120° C. for 5 minutes to obtain adsorbent D of Example 1.

[0077] Here, in order to uniformly coat the surface of the adsorbent A with the thermoplastic resin C, the thermoplastic resin C is attached to the adsorbent A in advance. However, this is not limiting, and the adsorbent A, adsorbent B, and thermoplastic resin C may be mixed together and heated and stirred.

[0078] An adsorption filter was fabricated using the adsorbent D of Example 1 as follows. A thermal bonded nonwoven fabric substrate was used as the downstream layer. A mixture of adsorbent D and a thermoplastic powder resin as an adhesive to the substrate in a weight ratio of 20:1 was applied to the downstream layer to a basis weight of 300 g / m. ２ The downstream layer coated with adsorbent D and adhesive was overlaid with an electret nonwoven fabric substrate as an upstream layer, and heated to obtain an adsorption filter in which adsorbent D was supported between the nonwoven fabrics. The performance of this adsorption filter was measured. The adsorbent conditions and performance measurement results are shown in Table 1.

[0079] Example 2: Granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) was used as adsorbent A. ２ / g, pore volume 0.46 cm ３The thermoplastic resin C was adhered to the surface of the adsorbent A by mixing and stirring a mixture of an ethylene acrylic acid copolymer resin (average particle length 10 μm, melt index value 9 g / 10 min) as the thermoplastic resin C in a weight ratio of 20:1. Next, a type B silica gel (average particle length 20 μm, specific surface area 450 m) impregnated with 0.1 wt % adipic acid dihydrazide was used as the adsorbent B. ２ The same amount of the thermoplastic resin C (1 / g) was weighed out, and the mixture was heated and stirred at 120°C for 5 minutes to obtain an adsorbent D of Example 2.

[0080] An adsorption filter was fabricated using Adsorbent D of Example 2 as follows. A thermal bonded nonwoven fabric substrate was used as the downstream layer. A mixture of Adsorbent D and a thermoplastic powder resin as an adhesive to the substrate in a weight ratio of 20:1 was applied to the downstream layer to a basis weight of 300 g / m. ２ The downstream layer coated with adsorbent D and adhesive was overlaid with the electret nonwoven fabric substrate as the upstream layer, and heated to obtain an adsorption filter in which adsorbent D was supported between the nonwoven fabrics. The performance of this adsorption filter was measured. The adsorbent conditions and performance measurement results are shown in Table 1.

[0081] Comparative Example 1 Granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) ２ / g, pore volume 0.46 cm ３ An adsorption filter was fabricated as follows using a thermobonded nonwoven fabric as the downstream layer, and a mixture of the adsorbent of Comparative Example 1 and a thermoplastic powder resin as an adhesive to the substrate in a weight ratio of 20:1 was laid on top of the downstream layer to a basis weight of 300 g / m. ２ The adsorption filter was then measured for various performance characteristics. The adsorbent conditions and performance measurement results are shown in Table 1.

[0082] Comparative Example 2: Granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) ２ / g, pore volume 0.46 cm ３ / g, average pore diameter 17 Å) and B-type silica gel (average particle length 20 μm, specific surface area 450 m) impregnated with 0.1 wt% adipic acid dihydrazide. ２ A mixture of the adsorbent and the thermoplastic powder resin (adhesive for the substrate) at a weight ratio of 20:1 was used as the adsorbent of Comparative Example 2. An adsorption filter was fabricated using this adsorbent as follows: A thermal bond nonwoven fabric was used as the downstream layer, and a mixture of the adsorbent of Comparative Example 2 and a thermoplastic powder resin (adhesive for the substrate) at a weight ratio of 20:1 was placed on top of this downstream layer, with a basis weight of 300 g / m. ２ The adsorption filter was then measured for various performance characteristics. The adsorbent conditions and performance measurement results are shown in Table 1.

[0083]

[0084] As can be seen from Table 1, Example 1 and Comparative Example 1 used the same average particle length of granular activated carbon, and therefore the pressure loss was equivalent. However, Comparative Example 1 did not use adsorbent B, and therefore the initial toluene removal rate was lower than that of Example 1.

[0085] Similarly, Example 2 and Comparative Example 1 used the same average particle length of granular activated carbon, and therefore had comparable pressure losses, but Comparative Example 1 did not use adsorbent B, and therefore had lower initial acetaldehyde removal rates and acetaldehyde adsorption capacities than Example 2. This shows that the effects of the first disclosure can be achieved by adhering adsorbent B to the surface of adsorbent A, regardless of the type of adsorbent.

[0086] In Example 2 and Comparative Example 2, the type and amount of adsorbent used are the same, and therefore the adsorption performance is the same. On the other hand, the filter using the adsorbent of Example 2 has low pressure loss. Therefore, the adsorbent of the first disclosure has high adsorption capacity for harmful molecules such as toluene and acetaldehyde, and can reduce pressure loss when used as an adsorption filter.

[0087] <Second Disclosure> Regarding the second disclosure, first, each measurement method will be described.

[0088] (Number of adsorbents B adhering to adsorbent A) Ten adsorbents obtained in each of the examples and comparative examples were observed under a scanning electron microscope (SEM). From the SEM observation photographs, the number of adsorbents B adhering to the surface of each adsorbent A was counted. Assuming that the same number of adsorbents B were adhering to the surface opposite to the observation surface, this number was doubled, and the average of the obtained 10 measurements was taken as the number of adsorbents B adhering to adsorbent A. In this case, the number was rounded to the nearest ten.

[0089] (Proportion of Adsorbent B Adhering to Adsorbent A) One side of the nonwoven fabric was peeled off from the adsorption filter obtained in each Example and Comparative Example, and observation was performed using a scanning electron microscope (SEM) so that at least 10 particles of adsorbent A were included in one field of view. Of the total number of adsorbents B (100%) captured in the SEM observation photograph, the number of adsorbents B adhering to the surface of adsorbent A and the number of adsorbents B not adhering to the surface of adsorbent A but present in the gaps between adsorbents A were determined by visual estimation, and the proportion of adsorbents B adhering to adsorbent A was calculated.

[0090] (Toluene Removal Performance, Acetaldehyde Removal Performance, and Filtration Performance) The toluene removal performance, acetaldehyde removal performance, and filtration performance were measured in the same manner as in the first disclosure.

[0091] Example 1A: Granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) was used as adsorbent A. ２ / g, pore volume 0.46 cm ３ The thermoplastic resin C was adhered to the surface of the adsorbent A by mixing and stirring an ethylene acrylic acid copolymer resin (average particle length 10 μm, melt index value 9 g / 10 min) as the thermoplastic resin C at a weight ratio of 20:1. Next, powdered activated carbon (average particle length 10 μm, specific surface area 1100 m) as the adsorbent B was added. ２ / g, pore volume 0.52 cm ３ The same amount of thermoplastic resin C (1 / g, average pore diameter 18 Å) was weighed out, and the mixture was heated and stirred at 120°C for 5 minutes. This produced an adsorbent of Example 1A in which adsorbent B (powdered activated carbon) was fixed to the surface of adsorbent A (granular activated carbon).

[0092] Here, in order to uniformly coat the surface of the adsorbent A with the thermoplastic resin C, the thermoplastic resin C is attached to the adsorbent A in advance. However, this is not limiting, and the adsorbent A, adsorbent B, and thermoplastic resin C may be mixed together and heated and stirred.

[0093] An adsorption filter was fabricated using the adsorbent of Example 1A as follows: A thermal bonded nonwoven fabric substrate was used as the downstream layer, and a mixture of the adsorbent of Example 1A and a thermoplastic powder resin as an adhesive to the substrate in a weight ratio of 20:1 was applied to the downstream layer to a basis weight of 300 g / m. ２ The adsorption filter of Example 1A was obtained by stacking the electret nonwoven fabric substrate as an upstream layer on the downstream layer coated with the adsorbent and adhesive of Example 1A and heating the nonwoven fabric to carry the adsorbent of Example 1A between the layers of nonwoven fabric. The performance of this adsorption filter was measured. The adsorbent conditions and performance measurement results are shown in Table 2.

[0094] Example 2A: Granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) was used as adsorbent A. ２ / g, pore volume 0.46 cm ３ The thermoplastic resin C was adhered to the surface of the adsorbent A by mixing and stirring a mixture of an ethylene acrylic acid copolymer resin (average particle length 10 μm, melt index value 9 g / 10 min) as the thermoplastic resin C in a weight ratio of 20:1. Next, a type B silica gel (average particle length 20 μm, specific surface area 450 m) impregnated with 0.1 wt % adipic acid dihydrazide was used as the adsorbent B. ２ The same amount of thermoplastic resin C (1 / g) was weighed out and heated and stirred at 120°C for 5 minutes. This resulted in an adsorbent of Example 2A in which adsorbent B (powdered activated carbon) was fixed to the surface of adsorbent A (granular activated carbon). An SEM photograph of the resulting adsorbent is shown in Figure 1.

[0095] An adsorption filter was fabricated using the adsorbent of Example 2A as follows. A thermal bonded nonwoven fabric substrate was used as the downstream layer. A 20:1 weight ratio mixture of the adsorbent and a thermoplastic powder resin as an adhesive to the substrate was applied to the downstream layer to a basis weight of 300 g / m. ２The adsorption filter of Example 2A was obtained by stacking the electret nonwoven fabric substrate as the upstream layer on the downstream layer coated with the adsorbent and adhesive, and heating the resulting adsorption filter with the adsorbent of Example 2A supported between the nonwoven fabrics. The performance of this adsorption filter was measured. The adsorbent conditions and performance measurement results are shown in Table 2. Figure 2 shows an SEM photograph taken after peeling off the nonwoven fabric on one side of the adsorption filter of Example 2A.

[0096] Comparative Example 1A: Granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) ２ / g, pore volume 0.46 cm ３ An adsorption filter was fabricated as follows using the adsorbent of Comparative Example 1A (average pore size: 17 Å). A thermal bonded nonwoven fabric was used as the downstream layer, and a mixture of the adsorbent of Comparative Example 1A and a thermoplastic powder resin as an adhesive to the substrate in a weight ratio of 20:1 was placed on top of the downstream layer to a basis weight of 300 g / m. ２ The adsorption filter of Comparative Example 1A was obtained by stacking an electret nonwoven fabric as an upstream layer on the downstream layer coated with the adsorbent and adhesive, and heating the nonwoven fabric to obtain the adsorption filter of Comparative Example 1A in which the adsorbent of Comparative Example 1A was supported between the nonwoven fabrics. The performance of this adsorption filter was measured. The adsorbent conditions and performance measurement results are shown in Table 2.

[0097] Comparative Example 2A: Granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) ２ / g, pore volume 0.46 cm ３ / g, average pore diameter 17 Å) and B-type silica gel (average particle length 20 μm, specific surface area 450 m) impregnated with 0.1 wt% adipic acid dihydrazide. ２ The adsorbent of Comparative Example 2A was prepared by mixing the adsorbent and the thermoplastic powder resin at a weight ratio of 20:1. This adsorbent was used to prepare an adsorption filter as follows: A thermal bonded nonwoven fabric was used as the downstream layer, and a base material was coated on the downstream layer with a mixture of the adsorbent of Comparative Example 2A and a thermoplastic powder resin as an adhesive to the base material at a weight ratio of 20:1. ２The adsorption filter of Comparative Example 2A was obtained by stacking an electret nonwoven fabric as an upstream layer on the downstream layer coated with the adsorbent and adhesive, and heating the resulting adsorption filter. The adsorbent of Comparative Example 2A was supported between the nonwoven fabrics. The performance of this adsorption filter was measured. The adsorbent conditions and performance measurement results are shown in Table 2. An SEM photograph taken after peeling off one side of the nonwoven fabric is shown in Figure 3.

[0098]

[0099] As can be seen from Table 2, Example 1A and Comparative Example 1A had the same average particle length of the granular activated carbon used, and therefore the pressure loss was equivalent. However, Comparative Example 1A did not use adsorbent B, and therefore the initial toluene removal rate was lower than that of Example 1A.

[0100] Similarly, Example 2A and Comparative Example 1A had the same pressure loss because the average particle length of the granular activated carbon used was the same, but Comparative Example 1A did not use adsorbent B, and therefore the initial acetaldehyde removal rate and acetaldehyde adsorption capacity were lower than those of Example 1A. This shows that the effect of the second disclosure can be achieved by adhering adsorbent B to the surface of adsorbent A, regardless of the type of adsorbent.

[0101] In Example 2A and Comparative Example 2A, the type and amount of adsorbent used are the same, so the adsorption performance is the same. On the other hand, the filter using the adsorbent of Example 2A has low pressure loss. Therefore, the adsorption filter of the second disclosure has high adsorption capacity for harmful molecules such as toluene and acetaldehyde, and can also reduce pressure loss.

[0102] By using the adsorbent and adsorption filter of the present disclosure, it is possible to efficiently remove contaminants, including volatile organic compounds such as toluene and aldehydes, with low pressure loss, which is expected to make a significant contribution to the industrial sector.

Claims

1. An adsorbent comprising: adsorbent A having an average particle length of 200 to 900 μm; adsorbent B having an average particle length of 0.1 to 100 μm; and thermoplastic resin C having an average particle length of 0.1 to 100 μm, wherein adsorbent B is fixed to the surface of adsorbent A via thermoplastic resin C.

2. The adsorbent according to claim 1, wherein the weight ratio of adsorbent A to adsorbent B is 100:1-20.

3. The adsorbent according to claim 1, wherein the weight ratio of said adsorbent A to said thermoplastic resin C is 100:1-20.

4. The adsorbent of claim 1, wherein said adsorbent A comprises activated carbon, activated alumina, silica gel, zeolite, or a mixture thereof.

5. The adsorbent of claim 1, wherein said adsorbent B comprises activated carbon, activated alumina, silica gel, zeolite, or a mixture thereof.

6. The adsorbent according to claim 1, wherein the thermoplastic resin C comprises at least one selected from the group consisting of polyolefin resins, polyamide resins, polyester resins, polyacrylic resins, and copolymers thereof.

7. An adsorption filter comprising the adsorbent according to any one of claims 1 to 6 and a substrate.

8. An adsorption filter comprising: adsorbent A having an average particle length of 200 to 900 μm; adsorbent B having an average particle length of 0.1 to 100 μm; thermoplastic resin C having an average particle length of 0.1 to 100 μm; and a substrate, wherein said adsorbent A, said adsorbent B, and said thermoplastic resin C are supported on said substrate, and 500 or more particles of said adsorbent B are fixed to each particle of said adsorbent A via said thermoplastic resin C, and when the total number of said adsorbents B is taken as 100%, 65% or more of said adsorbents B are fixed to said adsorbent A via said thermoplastic resin C.

9. The adsorption filter according to claim 8, wherein the weight ratio of adsorbent A to adsorbent B is 100:1-20.

10. The adsorption filter according to claim 8 or 9, wherein the weight ratio of said adsorbent A to said thermoplastic resin C is 100:1-20.

11. The adsorption filter of claim 8 or 9, wherein said adsorbent A comprises activated carbon, activated alumina, silica gel, zeolite, or a mixture thereof.

12. The adsorption filter of claim 8 or 9, wherein said adsorbent B comprises activated carbon, activated alumina, silica gel, zeolite, or a mixture thereof.

13. An adsorption filter according to claim 8 or 9, wherein the thermoplastic resin C comprises at least one selected from the group consisting of polyolefin resins, polyamide resins, polyester resins, polyacrylic resins, and copolymers thereof.

14. An adsorption filter as described in claim 8 or 9, wherein 500 or more and 2,000,000 or less particles of adsorbent B are fixed to each particle of adsorbent A via thermoplastic resin C, and when the total number of adsorbents B is taken as 100%, 65% or more and 100% or less of adsorbents B are fixed to adsorbent A via thermoplastic resin C.

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