Adsorbent, adsorption filter, filter unit, and method for manufacturing adsorption filter

Abstract

Provided is an adsorbent having high removal performance with respect to a contaminant such as a volatile organic compound, the adsorbent being capable of forming an adsorption filter that undergoes low pressure loss when the adsorption filter is manufactured using the adsorbent.　This adsorbent contains an adsorbent A having an average particle long diameter of 200-1000 μm and an adsorbent B having an average particle long diameter of 0.1-100 μm. The adsorbent B is fixed to the surface of the adsorbent A. The number of adsorbents B fixed per one adsorbent A is 500 or more.

Description

Adsorbent, adsorption filter, filter unit, and method for manufacturing adsorption filter

[0001] The present invention relates to an adsorbent, an adsorption filter, a filter unit for removing pollutants, and a method for manufacturing an adsorption filter.

[0002] In recent years, there has been growing interest in combating odor pollution as one of the countermeasures for environmental problems. Examples of odor pollution include pollution caused by exhaust gases. Volatile organic compounds, such as toluene and acetaldehyde, are considered to be causative agents of sick house syndrome, and the removal and deodorization of these odorous substances is a major challenge. It is known that these exhaust gases can be removed by 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, for example, Patent Document 1 discloses a method for achieving low pressure loss by bonding and aggregating activated carbon particles of the same particle diameter with a thermoplastic resin to form irregular aggregates, thereby creating voids between the aggregates. Patent Document 2 discloses a method for achieving high volatile organic compound removal performance by supporting particles with an average particle diameter of 1 μm or less on a nonwoven fabric.

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

[0005] However, the filter of Patent Document 1 has problems such as the aggregates breaking down due to external forces 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 filter of Patent Document 2 has problems such as the particles used having a small particle diameter, and the adsorbent particles filling voids between the fibers of the nonwoven fabric, resulting in increased pressure loss.

[0006] In view of the above circumstances, the present invention aims to provide an adsorbent having high performance in removing pollutants including volatile organic compounds, an adsorption filter having high performance in removing pollutants and low pressure loss, a filter unit including an adsorption filter, and a method for manufacturing an adsorption filter.

[0007] The adsorbents according to the embodiments of the present invention that have been able to solve the above problems are as follows: [1] An adsorbent comprising an adsorbent A having an average particle length of 200 μm to 1000 μm and an adsorbent B having an average particle length of 0.1 μm to 100 μm, wherein the adsorbent B is adhered to the surface of the adsorbent A, and the number of the adsorbent B adhered to each particle of the adsorbent A is 500 or more.

[0008] The adsorbent contains adsorbent B, which has a small average particle length of 0.1 μm to 100 μm, thereby increasing the surface area for adsorbing contaminants and increasing the contaminant removal rate. Furthermore, since 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 1000 μm, an adsorption filter with low pressure loss can be obtained when the adsorbent is used to prepare the adsorption filter.

[0009] The adsorbent according to the embodiment of the present invention preferably has any one of the following [2] to [7]: [2] The average particle length R of the adsorbent A Ａ and the average particle major axis R of the adsorbent B Ｂ The ratio R Ｂ / R Ａ [3] The adsorbent according to [1], wherein the average particle length R of the adsorbent A is 1 / 5000 to 1 / 5. Ａ , the average particle major axis R of the adsorbent B Ｂ , and the weight ratio P ((weight of adsorbent A) / (weight of adsorbent B)) of the adsorbent A and the adsorbent B is P=R Ａ ３ / [{(R Ａ +2R Ｂ ) ３ -R Ａ ３}×X], where X is 0.1 or more and 10 or less. [4] The adsorbent according to any one of [1] to [3], wherein the adsorbent A is any one of activated carbon, activated alumina, silica gel, and zeolite. [5] The adsorbent according to any one of [1] to [4], wherein the adsorbent B is any one of activated carbon, activated alumina, silica gel, and zeolite. [6] The adsorbent according to any one of [1] to [5], wherein the adsorbent B is fixed to the surface of the adsorbent A via a binder. [7] The adsorbent according to [6], wherein the binder is at least one selected from the group consisting of sodium alginate, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyethylene glycol, polypropylene glycol, polyvinyl acetate, and copolymers thereof.

[0010] The adsorption filter according to the embodiment of the present invention that has solved the above problems is as follows: [8] An adsorption filter comprising the adsorbent according to any one of [1] to [7] above and a substrate, wherein the adsorbent A and the adsorbent B are supported on the substrate, and when the total number of the adsorbents B is taken as 100%, 65% or more of the adsorbents B are fixed to the surface of the adsorbent A. [9] An adsorption filter according to [8], wherein the substrate is a nonwoven fabric.

[0011] The above-mentioned adsorption filter contains small adsorbent B particles with an average particle length of 0.1 μm to 100 μm, thereby increasing the surface area for adsorbing contaminants and increasing the contaminant removal rate. Furthermore, by adhering 500 or more particles of small adsorbent B particles to the surface of large adsorbent A particles with an average particle length of 200 μm to 1000 μm, it becomes easy to create voids between the adsorbent particles. Furthermore, since 65% or more of the total number of adsorbent B particles is adhered to the surface of adsorbent A, there is little free adsorbent B present on the surface of adsorbent A, preventing adsorbent B from filling gaps in the substrate and causing clogging. This allows for an adsorption filter with low pressure loss.

[0012] The present invention also provides a method for manufacturing the above-mentioned adsorption filter. The manufacturing method is as follows:

[10] The method comprises the steps of preparing an adsorbent A having an average particle length of 200 μm to 1000 μm, an adsorbent B having an average particle length of 0.1 μm to 100 μm, and a substrate, adsorbent B being fixed to the surface of adsorbent A to obtain an adsorbent, and adsorbent being supported on the substrate, wherein the weight W of adsorbent A is 200 μm to 1000 μm, and the adsorbent B is 0.1 μm to 100 μm. Ａ and the weight W of the adsorbent B Ｂ Ratio of W Ａ / W Ｂ The value P is 0.3 or more and 150 or less, and when the total number of adsorbents B is 100%, 65% or more of the adsorbents B are fixed to the surface of the adsorbents A.

[0013] According to the above-mentioned method for manufacturing an adsorption filter, by using an adsorbent B having a small average particle length of 0.1 μm to 100 μm, the surface area for adsorbing contaminants can be increased, and therefore the removal rate of contaminants can be increased. In addition, the adsorbent B having a small average particle length is fixed to the surface of the adsorbent A having a large average particle length of 200 μm to 1000 μm, and the weight W of the adsorbent A is Ａ and the weight W of the adsorbent B Ｂ Ratio of W Ａ / W Ｂ By setting the value P between 0.3 and 150, it becomes easy to create voids between the adsorbent particles. Furthermore, since 65% or more of the total 100% of the adsorbent B is fixed to the surface of the adsorbent A, there is little adsorbent B remaining free from the surface of the adsorbent A, and it is possible to prevent adsorbent B from filling the gaps in the substrate and causing clogging. This makes it possible to manufacture an adsorption filter with low pressure loss.

[0014] The method for producing an adsorption filter according to an embodiment of the present invention is preferably any one of the following

[11] to

[17] .

[11] The average particle length R of the adsorbent A Ａ and the average particle major axis R of the adsorbent B Ｂ The ratio R Ｂ / R Ａ

[12] The method for manufacturing an adsorption filter according to

[10] , wherein the average particle length R of the adsorbent A is 1 / 5000 to 1 / 5. Ａ , the average particle major axis R of the adsorbent B Ｂ , and the weight ratio P of the adsorbent A to the adsorbent B ((the weight W of the adsorbent A) Ａ ) / (weight W of adsorbent B Ｂ )) is P=R Ａ ３ / [{(R Ａ +2R Ｂ ) ３ -R Ａ ３}×X], where X is 0.1 or more and 10 or less.

[13] The method for manufacturing an adsorption filter according to any one of

[10] to

[12] , wherein the step of adsorbent B being fixed to the surface of adsorbent A to obtain an adsorbent includes a step of mixing adsorbent A, adsorbent B, and a binder.

[14] The method for manufacturing an adsorption filter according to

[13] , wherein the binder is at least one selected from the group consisting of sodium alginate, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyethylene glycol, polypropylene glycol, polyvinyl acetate, and copolymers thereof.

[15] The method for manufacturing an adsorption filter according to any one of

[10] to

[14] , wherein adsorbent A is activated carbon, activated alumina, silica gel, or zeolite.

[16] The method for manufacturing an adsorption filter according to any one of

[10] to

[15] , wherein the adsorbent B is any one of activated carbon, activated alumina, silica gel, and zeolite.

[17] The method for manufacturing an adsorption filter according to any one of

[10] to

[16] , wherein the substrate is a nonwoven fabric.

[0015] Other embodiments of the adsorption filter of the present invention that solve the above problems are as follows.

[18] An adsorption filter comprising at least a substrate A, an adsorption layer, and a substrate B laminated in the listed order, wherein the adsorption layer contains activated carbon, and the average particle length of the activated carbon is 300 μm to 700 μm.

[19] The adsorption filter according to

[18] , wherein the quality factor value, as expressed by the following formula, is 0.8 or greater: Quality factor value = Ln {(100 - toluene deodorization efficiency [%]) / 100} / pressure loss of adsorption layer [mmAq].

[20] The adsorption filter according to

[18] or

[19] , wherein the substrate A is a thermal-bonded nonwoven fabric or a spun-bonded nonwoven fabric.

[21] The adsorption filter according to any one of

[18] to

[20] , wherein the substrate B is a needle-punched nonwoven fabric, a thermal-bonded nonwoven fabric, a melt-blown nonwoven fabric, or a spun-bonded nonwoven fabric.

[0016] The present invention also provides the following filter unit:

[22] A filter unit comprising the adsorption filter according to any one of

[18] to

[21] above.

[0017] The adsorbent described above can improve the removal performance of pollutants such as volatile organic compounds. It is also possible to provide a filter and filter unit that can efficiently adsorb the substances to be removed with low pressure loss. Furthermore, the method for manufacturing the adsorption filter described above can manufacture an adsorption filter that can improve the removal rate of pollutants such as volatile organic compounds while reducing pressure loss, thereby improving the pollutant removal performance.

[0018] 1 is a scanning electron microscope photograph of the adsorbent obtained in Example 2. FIG. 2 is a scanning electron microscope photograph of the adsorption filter obtained in Example 2 after the substrate was removed. FIG. 3 is a scanning electron microscope photograph of the adsorption filter obtained in Comparative Example 4 after the substrate was removed. FIG. 4 is a graph showing the relationship between the toluene removal rate and pressure loss when adsorption filters are made using the adsorbents of Examples 1 to 16 and Comparative Examples 1 to 6. FIG. 5 is a graph showing the relationship between the toluene removal rate and pressure loss when adsorption filters are made using the adsorbents of Example 17 and Comparative Example 7.

[0019] The present invention will be described below based on the embodiments, but the present invention is not limited to the following embodiments, and it is of course possible to implement the present invention by making appropriate modifications within the scope that can comply with the purpose described above and below, and all of these modifications are included in the technical scope of the present invention.

[0020] (Adsorbent) The adsorbent according to an embodiment of the present invention comprises an adsorbent A having an average particle length of 200 μm to 1000 μm and an adsorbent B having an average particle length of 0.1 μm to 100 μm, the adsorbent B being adhered to the surface of the adsorbent A, and the number of particles of adsorbent B adhered to each particle of adsorbent A being 500 or more. Thus, the adsorbent according to an embodiment of the present invention comprises adsorbent A and adsorbent B, but in order to avoid confusion with adsorbent A and adsorbent B, the adsorbent according to an embodiment of the present invention will hereinafter be referred to as "adsorbent C."

[0021] Since adsorption occurs at the interface between the gas phase, liquid phase, or solid phase and the adsorbent, increasing the contact probability at the interface between the adsorbent and the adsorbed substance allows the adsorbed substance to be adsorbed to the adsorbent with high efficiency. The adsorbent C according to an embodiment of the present invention contains adsorbent B, which has a small average particle length of 0.1 μm to 100 μm, and therefore has a large surface area per unit volume, thereby achieving a high removal rate of contaminants. Furthermore, when adsorbent C is formed into a sheet to form an adsorption filter, if the particle size of the particles contained in adsorbent C is small, the voids are filled, resulting in a high packing density and resulting in high pressure loss. In contrast, in the adsorbent C according to an embodiment of the present invention, 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 1000 μm. As a result, when an adsorption filter is produced using adsorbent C, voids are likely to form between the particles, preventing the packing density from becoming too high, resulting in an adsorption filter with low pressure loss.

[0022] In producing adsorbent C, adsorbent A having an average particle length of 200 μm to 1000 μm and adsorbent B having an average particle length of 0.1 μm to 100 μm can be obtained by sieving 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, or adsorbent B having a small average particle length can be obtained by sieving through a No. 160 mesh or larger.

[0023] After being produced as adsorbent C, the major axes of adsorbent A and adsorbent B contained in adsorbent C can be measured from a micrograph such as a scanning electron microscope (SEM). The major axes of adsorbent A and adsorbent B can be determined by, for example, observing 100 particles of each of adsorbent A and adsorbent B with an SEM, measuring the length of the longest line segment connecting the outer edges of one particle, and averaging the measured values ​​for the 100 particles. 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 length of the diagonal of the rectangle. However, the shape of the particle is not limited to these shapes. Regardless of the shape of the particle, the major axis can be uniquely determined by the above definition.

[0024] The average particle length of adsorbent A is 200 μm or more, preferably 250 μm or more, more preferably 300 μm or more, even more preferably 350 μm or more, particularly preferably 375 μm or more, and may be 400 μm or more. If the lower limit of the average particle length of adsorbent A is within the above range, the pressure loss when an adsorption filter is produced using adsorbent C can be reduced. Furthermore, the average particle length of adsorbent A is 1000 μm or less, preferably 900 μm or less, more preferably 850 μm or less, even more preferably 800 μm or less, and may be 750 μm or less. If the upper limit of the average particle length of adsorbent A is within the above range, there is an advantage that when adsorbent C is formed into a sheet to produce an adsorption filter, the thickness does not become too thick, making production easier.

[0025] The average particle length of adsorbent B is 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 5 μm or more. When the lower limit of the average particle length of adsorbent B is within the above range, the cohesive force of adsorbent B does not become too strong, and adsorbent B can be uniformly fixed to the surface of adsorbent A. Furthermore, the average particle length of adsorbent B is 100 μm or less, preferably 75 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. When the upper limit of the average particle length of adsorbent B is within the above range, the fixing strength of adsorbent B to the surface of adsorbent A can be ensured, and it is easy to prevent adsorbent B from falling off from adsorbent A. When the average particle length of adsorbent B is within the above range, adsorbent B can be fixed to the surface of adsorbent A with uniform and strong fixing strength.

[0026] The number of adsorbents B fixed per particle of adsorbent A is 500 or more, preferably 600 or more, more preferably 800 or more, even more preferably 1,000 or more, and particularly preferably 2,000 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 improving the contaminant removal rate of adsorbent C. There is no particular upper limit on the number of adsorbents B fixed per particle of adsorbent A, but it may be, for example, preferably 2,000,000 or less, more preferably 1,000,000 or less, even more preferably 500,000 or less, particularly preferably 100,000 or less, or may be 80,000 or less, 50,000 or less, 30,000 or less, 10,000 or less, 9,000 or less, or 8,000 or less. The number of particles of adsorbent B that can adhere to the surface of adsorbent A depends on the size of the particles of adsorbent B relative to the surface area of ​​adsorbent A. However, if the upper limit of the particles of adsorbent B adhering to each particle of adsorbent A is within the above range, the particles of adsorbent B are less likely to fall off the surface of adsorbent A, and clogging due to the fallen particles of adsorbent can be prevented, thereby reducing pressure loss when an adsorption filter is produced using adsorbent C.

[0027] The adsorbent B may be directly fixed to the surface of the adsorbent A, or, as will be described later, the adsorbent B may be indirectly fixed to the surface of the adsorbent A via a binder. That is, in the adsorbent according to the embodiment of the present invention, the adsorbent B is directly or indirectly fixed to the surface of the adsorbent A.

[0028] 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 observing 10 particles of adsorbent C with an SEM, counting the number of particles of adsorbents B adhering to the surface of adsorbent A in each particle of adsorbent C, and then doubling this number assuming that the same number of particles of adsorbents B are adhering to the surface opposite to the observation surface, and then averaging the 10 measured values ​​thus obtained.

[0029] Average particle length R of adsorbent A Ａ and the average particle major axis R of the adsorbent B Ｂ The ratio R Ｂ / R Ａ The ratio R is preferably 1 / 5000 to 1 / 5, more preferably 1 / 1000 to 1 / 10, even more preferably 1 / 500 to 1 / 20, and most preferably 1 / 100 to 1 / 30. Ｂ / R Ａ When the ratio R is 1 / 5000 or more, the cohesive force of the adsorbent B does not become too strong, and the adsorbent B can be uniformly fixed to the surface of the adsorbent A. Ｂ / R Ａ When the ratio is 1 / 5 or less, the size of adsorbent B relative to the surface area of ​​adsorbent A does not become too large, making it easier to ensure the adhesive force of adsorbent B to the surface of adsorbent A and preventing adsorbent B from falling off from adsorbent A.

[0030] Average particle length R of adsorbent A Ａ , the average particle major axis R of the adsorbent B Ｂ and the weight ratio P of the adsorbent A to the adsorbent B ((weight of adsorbent A) / (weight of adsorbent B)) preferably satisfies the relationship of the following formula (1): P=R Ａ ３ / [{(R Ａ +2R Ｂ ) ３ -RＡ ３} × X] ... (1)

[0031] Equation (1) indicates that the weight ratio P ((weight of adsorbent A) / (weight of adsorbent B)) corresponds to (volume of adsorbent A) / (volume of adsorbent B). Here, the volume of adsorbent A is approximately R Ａ ３ In addition, in the case of adsorbent C, adsorbent B is fixed to both sides of adsorbent A, and the major axis R of adsorbent A is Ａ The major axis R of adsorbent B is Ｂ Add two times the volume of the adsorbent C and cube it to find the volume (R Ａ +2R Ｂ ) ３ From this, the volume of adsorbent A is calculated as R Ａ ３ By subtracting Ａ +2R Ｂ ) ３ -R Ａ ３ The smaller X is, the smaller the amount of adsorbent B adhering to the surface of adsorbent A is, and the larger X is, the larger the amount of adsorbent B adhering to the surface of adsorbent A is.

[0032] X is preferably 0.1 or more and 10 or less, more preferably 0.2 or more and 8.0 or less, even more preferably 0.4 or more and 5.0 or less, and most preferably 0.5 or more and 2.0 or less. When X is within this range, it is easy to obtain adsorbent C in which adsorbent B is uniformly adhered to the surface of adsorbent A. When X is less than 0.1, the amount of adsorbent B is too small, making it difficult to achieve the effects of the present invention. Furthermore, when X is greater than 10, it is thought that multiple layers of adsorbent B will accumulate on the surface of adsorbent A, and even if the amount of adsorbent B is increased so that X is greater than 10, it is unlikely that the effect of reducing the pressure loss of the adsorption filter will be improved compared to when X is 0.1 or more and 10 or less. Conversely, when X is too large, adsorbent B will be more likely to detach from the surface of adsorbent A, which is thought to increase the pressure loss of the adsorption filter. From this perspective, X is preferably 15 or less, more preferably 12 or less.

[0033] Adsorbent A and adsorbent B are preferably made of a material that can capture ions or molecules of contaminants, such as toluene or acetaldehyde, contained in the gas phase, thereby removing them from the gas phase.

[0034] The adsorbent A is not particularly limited as long as it is made of the above-mentioned material, but is preferably, for example, any one of activated carbon, activated alumina, silica gel, and zeolite. These may be used alone or in combination of two or more. To remove volatile organic compounds such as toluene and aldehydes, the adsorbent A is preferably composed of activated carbon or silica gel.

[0035] The adsorbent B is not particularly limited as long as it is made of the above-mentioned material, but is preferably, for example, any one of activated carbon, activated alumina, silica gel, and zeolite. These may be used alone or in combination of two or more. To remove volatile organic compounds such as toluene and aldehydes, the adsorbent B is preferably composed of activated carbon or silica gel.

[0036] The materials constituting adsorbent A and adsorbent B may be the same or different, but are preferably the same, which can ensure the adhesive force of adsorbent B to the surface of adsorbent A.

[0037] 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.

[0038] The BET specific surface area of ​​the activated carbon is not particularly limited, but is preferably 800 m ２ / g~1500m ２ / g is preferred, and 850m ２ / g~1300m ２ / g is more preferable. 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.

[0039] The pore volume of the activated carbon is not particularly limited, but is preferably 0.30 cm ３ / g to 0.70 cm ３ / g is preferred, and 0.40 cm ３ / g ~ 0.55 cm ３ / g is more preferable. 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.

[0040] The average pore diameter 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 diameter is preferably 15 Å to 19 Å, and more preferably 16 Å to 18 Å.

[0041] The BET specific surface area of ​​the silica gel is not particularly limited, but is preferably 20 m ２ / g to 1000m ２ / g is preferred, and 50m ２ / g~700m ２ / g is more preferable. 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.

[0042] It is preferable that adsorbent B be fixed to the surface of adsorbent A via a binder. This makes it easy for adsorbent B to be fixed to the surface of adsorbent A, and makes it easy to prevent adsorbent B from falling off the surface of adsorbent A. As a result, when adsorbent C is formed into a sheet to form an adsorption filter, it is possible to prevent the adsorbent B that has fallen off the surface of adsorbent A from filling voids formed by adsorbent A with a large average particle length, thereby preventing an increase in pressure loss.

[0043] The binder is not particularly limited as long as it can fix adsorbent B to the surface of adsorbent A, but examples include water-soluble polymers, thermoplastic resins, and water-dispersible polymers. In particular, the binder is preferably a water-soluble polymer. The water-soluble polymer preferably has a solubility in water of 1 g or more at 20°C and 1 atmosphere and a molecular weight of 10,000 or more. The binder is preferably a water-soluble polymer, and is preferably at least one selected from the group consisting of sodium alginate, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyethylene glycol, polypropylene glycol, polyvinyl acetate, and copolymers thereof.

[0044] By using a water-soluble polymer as the binder, adsorbent B can be easily fixed to the surface of adsorbent A even when the amount of binder added is small.

[0045] The binder solution concentration is preferably 0.1 wt % to 10 wt %, more preferably 1 wt % to 5 wt %. By having a binder solution concentration of 0.1 wt % or more, it is possible to ensure the adhesive force of adsorbent B to the surface of adsorbent A. By having a binder solution concentration of 10 wt % or less, it is possible to avoid the problem of the binder coating the adsorbent particles that occurs when the binder solution concentration exceeds 10 wt %. The binder solution concentration may be the solution concentration of the water-soluble polymer.

[0046] The method for producing adsorbent C, i.e., the method for fixing adsorbent B to the surface of adsorbent A, is not particularly limited, and examples thereof include a method in which adsorbent A and adsorbent B are immersed in an aqueous solution in which a water-soluble polymer is dissolved, stirred, and then dried, and a method in which an aqueous solution in which a water-soluble polymer is dissolved is formed into a mist or atomized form and sprayed onto adsorbent A and adsorbent B, and then dried.

[0047] The adsorbent C is a material intended to remove ions or molecules, such as toluene or acetaldehyde, contained in a gas phase by capturing them therein, and can be used for a variety of purposes. For example, the adsorbent C can be used in a filter attached to an air purification device such as an air purifier or an air conditioner, although this is not particularly limited.

[0048] The adsorption filter manufactured using adsorbent C can be obtained by molding the filter material. There is no particular limitation on the molding method, but it is preferable to process the filter material into a flat, pleated, or honeycomb shape. When used as a cross-flow filter, the pleated shape increases the contact area with the gas to be treated, and when used as a parallel flow filter, the honeycomb shape increases the removal rate of pollutants, while simultaneously achieving low pressure loss of the adsorption filter. The manufacturing method of the adsorption filter will be described in detail later.

[0049] The adsorbent C according to the embodiment of the present invention and a filter manufactured using the same can be used indoors, in vehicles, etc., and is preferably used for the purpose of removing volatile organic compounds such as toluene and aldehydes from wallpaper, furniture, interior materials, resin molded articles, electrical equipment, etc. It is also preferable to fill the adsorbent C in a breathable container such as a box, bag, or net, and leave it to stand or allow it to ventilate before use.

[0050] (First adsorption filter) The adsorption filter according to the first embodiment of the present invention (hereinafter sometimes referred to as the first adsorption filter) has the above-mentioned adsorbent and a substrate, with adsorbent A and adsorbent B supported on the substrate, adsorbent B adhering to the surface of adsorbent A, and the number of adsorbents B adhering to each particle of adsorbent A being 500 or more.

[0051] The description of adsorbent A and adsorbent B contained in the adsorbent according to the first embodiment of the present invention can be found in the above (Adsorbent) section, so that the description will be omitted below.

[0052] In the first adsorption filter, 500 or more particles of adsorbent B, which have a small average particle length, are fixed to the surface of adsorbent A, which has a large average particle length of 200 μm to 1000 μm. This facilitates the formation of voids between the adsorbent particles in the adsorption filter, preventing excessive packing density. Furthermore, since 65% or more of the total number of adsorbents B is fixed to the surface of adsorbent A, there is little adsorbent B remaining free from the surface of adsorbent A, preventing adsorbent B from filling gaps in the substrate and causing clogging. As a result, an adsorption filter with low pressure loss can be achieved. When the adsorption filter according to the embodiment of the present invention 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.

[0053] After being manufactured as an adsorption filter, the major axes of adsorbent A and adsorbent B contained in the adsorption filter can be measured from a photograph obtained by removing at least a portion of the substrate so that adsorbent A and adsorbent B can be observed, and then observing the filter with a microscope such as a scanning electron microscope (SEM).

[0054] The first adsorption filter has the advantage that the thickness of the adsorption filter does not become too large and is easy to manufacture because it contains adsorbent A having an average particle length within the predetermined range as described above. Also, the first adsorption filter has adsorbent B having an average particle length within the predetermined range as described above, so that adsorbent B can be adhered to the surface of adsorbent A with a uniform and strong adhesion force.

[0055] In the first adsorption filter, the number of adsorbents B fixed to each particle of adsorbent A is within a predetermined range, so that 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.

[0056] The adsorbent B may be directly fixed to the surface of the adsorbent A, or the adsorbent B may be indirectly fixed to the surface of the adsorbent A via a binder. That is, in the adsorbent according to the embodiment of the present invention, the adsorbent B is directly or indirectly fixed to the surface of the adsorbent A.

[0057] To determine the number of adsorbents B adhering to each particle of adsorbent A in the first adsorption filter, for example, at least a portion of the substrate is removed so that adsorbents A and B can be observed, and then 10 adsorbent particles are observed under an SEM. The number of adsorbents B adhering to the surface of adsorbent A in each case is counted, and assuming that the same number of adsorbents B are adhering to the surface opposite the observation surface, this number is doubled, and the average of the 10 measured values ​​obtained can be calculated.

[0058] 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 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.

[0059] 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.

[0060] The adsorption filter can be obtained by supporting adsorbent A and adsorbent B on a substrate. The substrate is preferably 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.

[0061] 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 processing methods (b), (c), and (e) among the above processing methods, since there is no need to use a surfactant and the adsorbent can be prevented from being covered with the surfactant.

[0062] When the above-mentioned adsorbent A and adsorbent B are supported on a substrate, it is preferable to support the adsorbent A with adsorbent B fixed to its surface on the substrate. That is, in the above-mentioned methods (a) to (f), "adsorbent A and adsorbent B" can be read as "adsorbent A with adsorbent B fixed to its surface." This makes it possible to easily fix the adsorbent B to the surface of the adsorbent A.

[0063] 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.

[0064] 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.

[0065] (Method for manufacturing an adsorption filter) A method for manufacturing an adsorption filter according to an embodiment of the present invention comprises the steps of preparing an adsorbent A having an average particle length of 200 μm to 1000 μm, an adsorbent B having an average particle length of 0.1 μm to 100 μm, and a substrate; adsorbent B being fixed to the surface of adsorbent A to obtain an adsorbent; and supporting the adsorbent consisting of adsorbent A and adsorbent B on the substrate.

[0066] Since adsorption occurs at the interface between the gas phase, liquid phase, or solid phase and the adsorbent, increasing the contact probability at the interface between the adsorbent and the adsorbed substance allows the adsorbed substance to be adsorbed to the adsorbent with high efficiency. The manufacturing method for an adsorption filter according to an embodiment of the present invention uses an adsorbent B with a small average particle length of 0.1 μm to 100 μm, thereby increasing the surface area per unit volume of the adsorbent in the manufactured adsorption filter and enabling the manufacture of an adsorption filter with a high removal rate of pollutants. Furthermore, when the particle size of the adsorbent particles is small, voids are filled, resulting in a high packing density and therefore high pressure loss. In this regard, the manufacturing method for an adsorption filter according to an embodiment of the present invention includes a step of adsorbing an adsorbent B with a small average particle length onto the surface of an adsorbent A with a large average particle length of 200 μm to 1000 μm to obtain an adsorbent, and the weight W of the adsorbent A is Ａ and the weight W of the adsorbent B Ｂ Ratio of W Ａ / W ＢAdsorbents A and B are used so that the value P is 0.3 or more and 150 or less. This makes it easy for voids to form between the adsorbent particles in the adsorption filter, preventing the packing density from becoming too high. Furthermore, since 65% or more of the total 100% of adsorbents B are fixed to the surface of adsorbent A, there is little adsorbent B remaining free from the surface of adsorbent A, preventing adsorbent B from filling gaps in the substrate and causing clogging. As a result, an adsorption filter with low pressure loss can be obtained. When an adsorption filter manufactured by the manufacturing method according to an embodiment of the present invention is installed 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.

[0067] Adsorbent A having an average particle length of 200 μm to 1000 μm and adsorbent B having an average particle length of 0.1 μm to 100 μm can be obtained by sieving 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, and adsorbent B having a small average particle length can be obtained by sieving through a No. 160 mesh or larger.

[0068] The average particle length of adsorbent A is 200 μm or more, preferably 250 μm or more, more preferably 300 μm or more, even more preferably 350 μm or more, particularly preferably 375 μm or more, and may be 400 μm or more. If the lower limit of the average particle length of adsorbent A is within the above range, the pressure loss of the adsorption filter can be reduced. Furthermore, the average particle length of adsorbent A is 1000 μm or less, preferably 900 μm or less, more preferably 850 μm or less, even more preferably 800 μm or less, and may be 750 μm or less. If the upper limit of the average particle length of adsorbent A is within the above range, there is an advantage that the thickness of the adsorption filter does not become too thick and manufacturing is facilitated.

[0069] The average particle length of adsorbent B is 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 5 μm or more. When the lower limit of the average particle length of adsorbent B is within the above range, the cohesive force of adsorbent B does not become too strong, and adsorbent B can be uniformly fixed to the surface of adsorbent A. Furthermore, the average particle length of adsorbent B is 100 μm or less, preferably 75 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. When the upper limit of the average particle length of adsorbent B is within the above range, the fixing strength of adsorbent B to the surface of adsorbent A can be ensured, and it is easy to prevent adsorbent B from falling off from adsorbent A. When the average particle length of adsorbent B is within the above range, adsorbent B can be fixed to the surface of adsorbent A with uniform and strong fixing strength.

[0070] The adsorbent B may be directly fixed to the surface of the adsorbent A, or, as will be described later, the adsorbent B may be indirectly fixed to the surface of the adsorbent A via a binder. That is, in the adsorbent according to the embodiment of the present invention, the adsorbent B is directly or indirectly fixed to the surface of the adsorbent A.

[0071] The method for fixing adsorbent B to the surface of adsorbent A is not particularly limited, and examples thereof include a method in which adsorbent A and adsorbent B are immersed in an aqueous solution in which a water-soluble polymer is dissolved, followed by stirring, and then drying; and a method in which an aqueous solution in which a water-soluble polymer is dissolved is formed into a mist or mist and sprayed onto adsorbent A and adsorbent B, followed by drying.

[0072] The step of adhering adsorbent B to the surface of adsorbent A preferably includes a step of mixing adsorbent A, adsorbent B, and a binder. By mixing adsorbent A, adsorbent B, and a binder, adsorbent B can be easily fixed to the surface of adsorbent A.

[0073] The binder is not particularly limited as long as it can fix adsorbent B to the surface of adsorbent A, but examples include water-soluble polymers, thermoplastic resins, and water-dispersible polymers. In particular, the binder is preferably a water-soluble polymer. The water-soluble polymer preferably has a solubility in water of 1 g or more at 20°C and 1 atmosphere and a molecular weight of 10,000 or more. The binder is preferably a water-soluble polymer, and is preferably at least one selected from the group consisting of sodium alginate, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyethylene glycol, polypropylene glycol, polyvinyl acetate, and copolymers thereof.

[0074] By using a water-soluble polymer as the binder, adsorbent B can be easily fixed to the surface of adsorbent A even when the amount of binder added is small.

[0075] The binder solution concentration is preferably 0.1 wt % to 10 wt %, more preferably 1 wt % to 5 wt %. By having a binder solution concentration of 0.1 wt % or more, it is possible to ensure the adhesive force of adsorbent B to the surface of adsorbent A. By having a binder solution concentration of 10 wt % or less, it is possible to avoid the problem of the binder coating the adsorbent particles that occurs when the binder solution concentration exceeds 10 wt %. The binder solution concentration may be the solution concentration of the water-soluble polymer.

[0076] The method for supporting an adsorbent consisting of 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 bonding, (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 processing methods (b), (c), and (e) among the above processing methods, since there is no need to use a surfactant and the adsorbent can be prevented from being covered with the surfactant.

[0077] The step of supporting an adsorbent consisting of adsorbent A and adsorbent B on a substrate is preferably performed after the step of adsorbent B being fixed to the surface of adsorbent A to obtain an adsorbent. That is, it is preferable to support adsorbent A with adsorbent B fixed to its surface on a substrate, and in the above methods (a) to (f), "adsorbent A and adsorbent B" can be read as "adsorbent A with adsorbent B fixed to its surface." This allows adsorbent B to be easily fixed to the surface of adsorbent A. This makes it easy to perform the step of fixing adsorbent B to the surface of adsorbent A. Alternatively, the step of fixing adsorbent B to the surface of adsorbent A to obtain an adsorbent and the step of supporting the adsorbent on a substrate may be performed simultaneously. In this case, the "step of supporting an adsorbent on a substrate" can be understood as the "step of supporting adsorbent A and adsorbent B on a substrate."

[0078] The substrate is preferably formed into a planar, pleated, or honeycomb shape. A pleated shape increases the contact area with the gas to be treated when used as a cross-flow filter, and a honeycomb shape increases the contact area with the gas to be treated when used as a parallel-flow filter, thereby improving the pollutant removal rate and simultaneously reducing the pressure loss of the filter.

[0079] 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.

[0080] Weight W of adsorbent A Ａ and the weight W of adsorbent B Ｂ Ratio of W Ａ / W Ｂ The value P of the ratio W is 0.3 or more, and can be 0.5 or more, 1 or more, 2 or more, 3 or more, 5 or more, 7 or more, 10 or more, etc. Ａ / W Ｂ The value P of the ratio W is 150 or less, and can be 120 or less, 100 or less, 90 or less, 80 or less, 70 or less, 50 or less, etc. Ａ / W Ｂ If the value P is within the above range, the surface area for adsorbing pollutants by adsorbent B can be increased, thereby increasing the pollutant removal rate, and voids can be secured by adsorbent A, thereby keeping the pressure loss of the adsorption filter low.

[0081] When the total number of adsorbents B is 100%, the number of adsorbents B adhering to the surface of adsorbent A is 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.

[0082] 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.

[0083] The number of adsorbents B fixed per particle of adsorbent A is preferably 500 or more, more preferably 600 or more, even more preferably 800 or more, even more preferably 1000 or more, and particularly preferably 2000 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 improving the contaminant removal rate. The upper limit of the number of adsorbents B fixed per particle of adsorbent A is not particularly limited, but may be, for example, preferably 2,000,000 or less, more preferably 1,000,000 or less, even more preferably 500,000 or less, particularly preferably 100,000 or less, or may be 80,000 or less, 50,000 or less, 30,000 or less, 10,000 or less, 9,000 or less, or 8,000 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.

[0084] 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 assuming that the same number of adsorbents B are adhering to the surface opposite the observation surface, doubling this number, and averaging the resulting 10 measured values.

[0085] Average particle length R of adsorbent A Ａ and the average particle major axis R of the adsorbent B Ｂ The ratio R Ｂ / R Ａ The ratio R is preferably 1 / 5000 to 1 / 5, more preferably 1 / 1000 to 1 / 10, even more preferably 1 / 500 to 1 / 20, and most preferably 1 / 100 to 1 / 30. Ｂ / R Ａ When the ratio R is 1 / 5000 or more, the cohesive force of the adsorbent B does not become too strong, and the adsorbent B can be uniformly fixed to the surface of the adsorbent A. Ｂ / R Ａ When the ratio is 1 / 5 or less, the size of adsorbent B relative to the surface area of ​​adsorbent A does not become too large, making it easier to ensure the adhesive force of adsorbent B to the surface of adsorbent A and preventing adsorbent B from falling off from adsorbent A.

[0086] Average particle length R of adsorbent A Ａ , the average particle major axis R of the adsorbent B Ｂ and the weight ratio P of the adsorbent A to the adsorbent B ((weight of adsorbent A) / (weight of adsorbent B)) preferably satisfies the relationship of the following formula (1): P=R Ａ ３ / [{(R Ａ +2R Ｂ ) ３ -R Ａ ３}×X] ...Formula (1)

[0087] Equation (1) indicates that the weight ratio P ((weight of adsorbent A) / (weight of adsorbent B)) corresponds to (volume of adsorbent A) / (volume of adsorbent B). Here, the volume of adsorbent A is approximately R Ａ ３ In addition, in the case of adsorbent C, adsorbent B is fixed to both sides of adsorbent A, and the major axis R of adsorbent A is Ａ The major axis R of adsorbent B is Ｂ Add two times the volume of the adsorbent and cube it to find the volume of the adsorbent (R Ａ +2R Ｂ ) ３ From this, the volume of adsorbent A is calculated as R Ａ ３ By subtracting Ａ +2R Ｂ ) ３ -R Ａ ３ The smaller X is, the smaller the amount of adsorbent B adhering to the surface of adsorbent A is, and the larger X is, the larger the amount of adsorbent B adhering to the surface of adsorbent A is.

[0088] X is preferably 0.1 or more and 10 or less, more preferably 0.2 or more and 8.0 or less, even more preferably 0.4 or more and 5.0 or less, and most preferably 0.5 or more and 2.0 or less. When X is within this range, adsorbent B can be uniformly fixed to the surface of adsorbent A. When X is less than 0.1, the amount of adsorbent B is too small, making it difficult to achieve the effects of the present invention. Furthermore, when X is greater than 10, it is thought that multiple layers of adsorbent B will accumulate on the surface of adsorbent A, and even if the amount of adsorbent B is increased so that X is greater than 10, it is unlikely that the effect of reducing the pressure loss of the adsorption filter will be improved compared to when X is 0.1 or more and 10 or less. Conversely, when X is too large, adsorbent B will be more likely to detach from the surface of adsorbent A, which is thought to increase the pressure loss of the adsorption filter. From this perspective, X is preferably 15 or less, more preferably 12 or less.

[0089] Adsorbent A and adsorbent B are preferably made of a material that can capture ions or molecules of contaminants, such as toluene or acetaldehyde, contained in the gas phase, thereby removing them from the gas phase.

[0090] The adsorbent A is not particularly limited as long as it is made of the above-mentioned material, but is preferably, for example, any one of activated carbon, activated alumina, silica gel, and zeolite. These may be used alone or in combination of two or more. To remove volatile organic compounds such as toluene and aldehydes, the adsorbent A is preferably composed of activated carbon or silica gel.

[0091] The adsorbent B is not particularly limited as long as it is made of the above-mentioned material, but is preferably, for example, any one of activated carbon, activated alumina, silica gel, and zeolite. These may be used alone or in combination of two or more. To remove volatile organic compounds such as toluene and aldehydes, the adsorbent B is preferably composed of activated carbon or silica gel.

[0092] The materials constituting adsorbent A and adsorbent B may be the same or different, but are preferably the same, which can ensure the adhesive force of adsorbent B to the surface of adsorbent A.

[0093] 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.

[0094] The BET specific surface area of ​​the activated carbon is not particularly limited, but is preferably 800 m ２ / g~1500m ２ / g is preferred, and 850m ２ / g~1300m ２ / g is more preferable. 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.

[0095] The pore volume of the activated carbon is not particularly limited, but is preferably 0.30 cm ３ / g to 0.70 cm ３ / g is preferred, and 0.40 cm ３ / g ~ 0.55 cm ３ / g is more preferable. 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.

[0096] The average pore diameter 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 diameter is preferably 15 Å to 19 Å, and more preferably 16 Å to 18 Å.

[0097] The BET specific surface area of ​​the silica gel is not particularly limited, but is preferably 20 m ２ / g to 1000m ２ / g is preferred, and 50m ２ / g~700m ２ / g is more preferable. 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.

[0098] The adsorption filter manufactured by the manufacturing method according to an embodiment of the present invention 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, the adsorption filter can be used indoors, in vehicles, etc., and is preferably used in wallpaper, furniture, interior materials, resin molded articles, electrical equipment, etc.

[0099] (Second Adsorption Filter) The present invention also provides an adsorption filter according to a second embodiment (hereinafter sometimes referred to as the second adsorption filter). The second adsorption filter is characterized in that it comprises at least a substrate A, an adsorption layer, and a substrate B laminated in the listed order, the adsorption layer containing activated carbon, and the activated carbon having an average particle length of 300 μm to 700 μm.

[0100] In the second adsorption filter, the average particle length of the activated carbon is preferably 300 to 700 μm, more preferably 350 to 650 μm. Within this range, even if the activated carbon basis weight is increased to achieve a certain level of adsorption performance, voids are maintained between the activated carbon particles, resulting in low pressure loss. If the average particle length is less than 300 μm, increasing the amount of activated carbon to achieve adsorption performance reduces voids and increases pressure loss. Furthermore, if the average particle length is greater than 700 μm, particles are more likely to fall out from between the substrates, and the filter unit may be poorly bent or corrugated when used to form a pleated or wavy air purification filter unit.

[0101] The average particle major axis can be determined by, for example, observing 100 pieces of activated carbon under an SEM, measuring the length of the longest line segment connecting the outer edges of each particle, and averaging the measurements of the 100 pieces. 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 length of the long side of the rectangle. However, the particle shape is not limited to these shapes. Regardless of the particle shape, the major axis can be uniquely determined by the above definition.

[0102] The particle size range of the activated carbon contained in the adsorption layer is not particularly limited, but taking into consideration breathability, activated carbon shedding, and sheet processability, for example, a value of 150 to 1000 μm, and more preferably 180 to 850 μm, as measured by ASTM standard sieves (ASTM E11). If the particle size range is less than 150 μm, increasing the weight of the activated carbon to achieve a certain level of adsorption performance reduces the void space and increases pressure loss. If the particle size range is greater than 1000 μm, shedding from the adsorption filter occurs, and processability during pleating or corrugation when forming air purification filter units into pleated or wavy shapes is impaired.

[0103] The activated carbon is not particularly limited, but it is preferable to use common activated carbon such as coconut shell activated carbon, coal activated carbon, wood activated carbon, and synthetic resin activated carbon in terms of performance and availability.

[0104] The BET specific 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 On the other hand, if the specific surface area is less than 1500 m / g, it is difficult to obtain the desired performance. ２ If the ion concentration exceeds 1 / g, the adsorbent is likely to be released from the adsorption filter.

[0105] 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 On the other hand, when the pore volume is less than 0.70 cm3 / g, it is difficult to obtain adsorption performance. ３ If the ion concentration exceeds 1 / g, the adsorbent is likely to be released from the adsorption filter.

[0106] 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.

[0107] The weight of activated carbon in the second adsorption filter is 50 to 700 g / m ２ is preferred, and 100 to 600 g / m ２ Within this range, a significant increase in pressure loss can be suppressed and sufficient deodorizing performance can be obtained. ２ If the weight of activated carbon is less than 700 g / m, sufficient adsorption performance will not be exhibited. ２ If the thickness is larger, the particles may fall off from the adsorption filter, or the processability of pleating or corrugating may be impaired when forming a filter unit for air purification into a pleated or corrugated shape.

[0108] The adsorption layer can efficiently adsorb and remove volatile organic compounds. Activated carbon may be treated with chemicals to improve its adsorption performance for polar substances and aldehydes. Chemicals used in gas chemical treatment include, for example, amine-based agents such as ethanolamine, polyethyleneimine, aniline, p-anisidine, and sulfanilic acid for aldehyde gases, nitrogen compounds such as NOx, sulfur compounds such as SOx, and acidic polar substances such as acetic acid; sodium hydroxide, potassium hydroxide, guanidine carbonate, guanidine phosphate, aminoguanidine sulfate, 5,5-dimethylhydantoin, benzoguanamine, 2,2-iminodiethanol, 2,2,2-nitrotriethanol, and ethanolamine. Suitable chemicals include methylamine 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 basic polar substances such as ammonia, methylamine, trimethylamine, and pyridine, suitable chemicals include phosphoric acid, citric acid, malic acid, ascorbic acid, and tartaric acid. Chemical treatment can be carried out, for example, by supporting or impregnating activated carbon with a chemical. In addition to treating activated carbon directly with a chemical, it is also possible to impregnate the filter by a conventional coating method near the filter surface or by impregnating the entire filter. In this case, a chemical aqueous solution containing a thickener such as sodium alginate or polyethylene oxide can be prepared and used for supporting or impregnating the filter. This method is effective in supporting and impregnating chemicals that have low solubility in water, and also in preventing the chemicals from falling off.

[0109] The adsorption layer may further contain an adhesive. Examples of adhesives include thermoplastic powder resins and hot melt sheets (e.g., spider web-shaped hot melt sheets), among which thermoplastic powder resins are preferred. Powder resins can be uniformly dispersed in activated carbon. Examples of types of thermoplastic powder resins include polyolefin resins, polyamide resins, polyester resins, and ethylene-acrylic copolymer resins.

[0110] When a thermoplastic powder resin is used as the adhesive, its size, in terms of average particle diameter, is preferably 10 to 500 μm, more preferably 5 to 30 μm. It is also desirable that 95% by weight or more of the resin be contained in the range of an average particle diameter of 1 to 40 μm. An average particle diameter within this range can reduce clogging of the surface pores of the activated carbon by the thermoplastic resin, while effectively pre-adhering to the activated carbon by van der Waals forces and electrostatic forces during mixing with the activated carbon, allowing for uniform dispersion and effectively preventing partial peeling between the adsorption layer and the substrate.

[0111] The shape of the thermoplastic powder resin used in the adhesive is not particularly limited, but examples include spherical and crushed shapes. Naturally, two or more types of thermoplastic powder resins can be used in combination. Furthermore, even when using chemical-loaded activated carbon or a chemical-loaded substrate, this formulation ensures that the thermoplastic powder resin is temporarily adhered to the surface of the activated carbon from the time of mixing in a dry state. Therefore, even if the chemicals have different properties, they can be prevented from interfering with each other in the subsequent sheet-forming process, thereby achieving sufficient effectiveness.

[0112] The thermoplastic powdered resin is preferably used in an amount of 1 to 40% by weight, more preferably 3 to 30% by weight, relative to the activated carbon. Within this range, an adsorption filter having excellent adhesive strength to the substrates A and B, pressure loss, and deodorizing performance can be obtained.

[0113] The quality factor value of the second adsorption filter, as shown in the following formula, is preferably 0.8 or more, and more preferably 1.0 or more. The higher the quality factor value, the better the adsorption performance and the lower the pressure loss. If the quality factor value is less than 0.8, there are problems such as low volatile organic compound removal performance, high pressure loss, or both. Quality factor value = -Ln {(100 - toluene deodorization efficiency [%]) / 100} / pressure loss of adsorption layer [mmAq]

[0114] Various sheet-like substrates can be used for the substrate A and the substrate B. As such a sheet-like substrate, a breathable woven or nonwoven fabric is preferred, and a nonwoven fabric is particularly preferred because the fibers are densely packed. As the nonwoven fabric, dry nonwoven fabrics such as thermal bonded nonwoven fabrics, needle punched nonwoven fabrics, and spunlace nonwoven fabrics, spunbonded nonwoven fabrics, meltblown nonwoven fabrics, wet nonwoven fabrics, etc. are preferably used depending on the application. The sheet-like substrate may be resin-processed. The sheet-like substrate may also be electret-processed.

[0115] The substrate A and the substrate B may be the same type of substrate or different types of substrates, and various combinations can be used as required.

[0116] The second adsorption filter may further contain components with additional functions, such as antibacterial agents, antifungal agents, antiviral agents, and flame retardants. These components may be kneaded into substrate A and / or substrate B, or may be attached and supported in post-processing. For example, by including a flame retardant, it is possible to manufacture an adsorption filter that meets the flame retardancy standards specified in FMVSS.302 and the UL flame retardancy standard. Additionally, components with additional functions may be added to the adsorption layer.

[0117] The second adsorption filter can be manufactured by the following method. First, the activated carbon and adhesive are weighed out to a predetermined weight, placed in a mixer, and stirred for approximately 10 minutes at a rotation speed of 30 rpm. Next, this mixed powder is scattered on the adhesive layer side of the substrate, and the substrate is then placed on top of it and heat-pressed. The surface temperature during heat-pressing is preferably 3 to 30°C higher than the melting point of the thermoplastic resin, and preferably 5 to 20°C higher.

[0118] The thickness of the adsorption filter is preferably 0.1 to 3.0 mm, more preferably 0.5 to 2.0 mm. If the thickness is less than 0.1 mm, the dust collection space is small, so the pressure loss increases quickly under dust load and clogging occurs. If the thickness exceeds 3.0 mm, the filter is too thick, and when it is made into a pleated unit, the structural resistance increases, resulting in a practical problem of high pressure loss throughout the unit.

[0119] Methods for finally heat-pressing the adsorption filter into a sheet include the roll-to-roll heat-press method commonly used in this field, and the flat-bed lamination method in which the filter is sandwiched between heated belt conveyors that are both flat on the top and bottom. The flat-bed lamination method is more preferred because it produces a more uniform thickness and adhesive state.

[0120] When pleating an adsorption filter, a general pleating machine such as a reciprocating or rotary type can be used. A heat-setting process may be performed to fix the pleat height and pitch to facilitate attachment of the frame material and to stabilize the shape of the adsorption filter during use. The heat treatment temperature during heat-setting is preferably set to a temperature equal to or higher than the melting point of the thermal adhesive fiber contained in the adhesive layer (about −10 to 20°C of the melting point) and equal to or lower than the melting point of the thermal adhesive fiber contained in the adhesive layer +30°C, thereby maintaining the pleated shape without pleating each other and maintaining the performance of the adsorption filter itself.

[0121] After the adsorption filter has been subjected to the necessary processing and cut to the necessary dimensions, it can be used as a filter unit either alone or in combination with a frame material, etc. Therefore, the filter unit is also included in the scope of the present invention.

[0122] This application claims the benefit of priority based on Japanese Patent Application Nos. 2023-107689, 2023-107690, 2023-107691, and 2023-158333, filed on June 30, 2023. The entire contents of the specifications of Japanese Patent Application Nos. 2023-107689, 2023-107690, 2023-107691, and 2023-158333, filed on September 22, 2023, are incorporated herein by reference.

[0123] The present invention will be described below with reference to examples. The present invention is not limited to the examples, and any design modifications made in accordance with the above and below spirit are included within the technical scope of the present invention.

[0124] (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.

[0125] (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.

[0126] (Measurement of toluene removal rate) Cross-sectional area: 36 cm ２ A sheet of adsorbent, i.e., an adsorption filter, was sandwiched between the columns. Air with a toluene vapor concentration of 80 ppm was supplied to the column at a linear velocity of 20 cm / sec, a temperature of 25°C, and a humidity of 50% RH. The toluene concentration at the column outlet was measured after 1 minute, and the removal rate (η) was calculated using the following formula (2). In the formula (2), Ci (ppm) is the toluene concentration at the inlet, and Co (ppm) is the toluene concentration at the outlet. The toluene concentration was measured using a hydrocarbon meter. Removal rate η (%) = [1 - (Co / Ci)] x 100 ... (2)

[0127] (Measurement of Pressure Loss) An adsorbent sheet, i.e., an adsorption filter, was placed in a duct, and the linear velocity of the sheet passing through was controlled to be 10.4 cm / sec. The pressure loss (mmAq) was determined by reading the static pressure difference between upstream and downstream of the sheet with a pressure gauge.

[0128] (Evaluation of Quality Factor Value) The quality factor value was calculated from the above-mentioned evaluation of toluene removal performance and the evaluation of pressure loss in the adsorption layer described below using the following formula: Quality factor value = -Ln {(100 - toluene deodorization efficiency [%]) / 100} / pressure loss in the adsorption layer [mmAq]

[0129] (Evaluation of Pressure Loss of Adsorption Layer) The pressure loss (mmAq) of the adsorption layer is evaluated using the following procedure. (1) The adsorption filter is installed in a duct, the linear velocity of the sheet passing through is controlled to 10.4 cm / sec, and the static pressure difference between the upstream and downstream of the sheet is read using a pressure gauge. (2) The adsorption layer is peeled off from the adsorption filter, and substrate A and substrate B are stacked without the adsorption layer, and the static pressure difference between the upstream and downstream is read using a pressure gauge using the above process. (3) The results of (1) and (2) are entered into the following formula to calculate the pressure loss of the adsorption layer. Pressure loss of the adsorption layer [mmAp] = Pressure loss of the adsorption filter [mmAp] - Pressure loss of substrate A and substrate B [mmAp]

[0130] Example 1: Granular activated carbon (average particle length: 300 μm, specific surface area: 1000 m) was used as adsorbent A. ２ / g, pore volume 0.46 cm ３ / g, average pore diameter 17 Å), and powdered activated carbon (average particle length 15 μm, specific surface area 1000 m) as adsorbent B. ２ / g, pore volume 0.46 cm ３ Activated carbon granules and powdered activated carbon (2000 sachets / g, average pore diameter 17 Å) were mixed in a weight ratio of 3:1, and an aqueous solution of sodium alginate (ALG-Na) was added in an amount of 0.46 times the total weight of the granular activated carbon and powdered activated carbon, and then mixed. The molecular weight of sodium alginate (ALG-Na) was 55,000, and the concentration of the aqueous solution of sodium alginate (ALG-Na) was 4.4 wt%. This was dried to obtain an adsorbent in which powdered activated carbon was fixed to the surface of the granular activated carbon. The obtained adsorbent was observed with an SEM, and the number of adsorbents B fixed to adsorbent A was determined from the SEM photographs using the method described above.

[0131] The adsorbent obtained above was formed into a sheet to produce an adsorption filter. The downstream layer was a thermal bonded nonwoven fabric, and the adsorbent obtained above and a thermoplastic powder resin as an adhesive were mixed in a weight ratio of 20:1. The resulting sheet had a basis weight of 200 g / m. ２The adsorption filter was heated using an electret nonwoven fabric as the upstream layer, and an adsorption filter with an adsorbent supported on the nonwoven fabric was obtained. The proportion of adsorbent B adhering to the surface of adsorbent A, the toluene removal rate, and the pressure loss were measured for this adsorption filter using the above-mentioned methods. The manufacturing conditions and measurement results are shown in Table 1.

[0132] Comparative Example 1 Granular activated carbon (average particle length: 300 μm, specific surface area: 1000 m) ２ / g, pore volume 0.46 cm ３ The adsorption filter was fabricated by forming a sheet of a thermo-bonded nonwoven fabric into a downstream layer. The adsorbent and a thermoplastic powder resin were mixed in a weight ratio of 20:1 to form a sheet with a basis weight of 200 g / m. ２ The adsorption filter was heated using an electret nonwoven fabric as the upstream layer, and the adsorption agent was supported on the nonwoven fabric to obtain an adsorption filter. The toluene removal rate and pressure loss of this adsorption filter were measured using the above-mentioned methods. The manufacturing conditions and measurement results of the adsorbent are shown in Table 1.

[0133]

[0134] In Example 1 and Comparative Example 1, the pressure loss was equivalent because the average particle length of the granular activated carbon (adsorbent A) used was the same. However, since powdered activated carbon (adsorbent B) was not used in Comparative Example 1, the toluene removal rate was lower than that of Example 1.

[0135] 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 ３ / g, average pore diameter 17 Å), and powdered activated carbon (average particle length 15 μm, specific surface area 1000 m) as adsorbent B. ２ / g, pore volume 0.46 cm ３Activated carbon granules and powdered activated carbon (17 Å / g, average pore diameter 17 Å) were mixed in a weight ratio of 7:1, and an aqueous solution of sodium alginate (ALG-Na) was added in an amount of 0.46 times the total weight of the granular activated carbon and powdered activated carbon, and then mixed. The molecular weight of sodium alginate (ALG-Na) was 55,000, and the concentration of the aqueous solution of sodium alginate (ALG-Na) was 4.4 wt%. This was dried to obtain an adsorbent in which powdered activated carbon was fixed to the surface of the granular activated carbon. An SEM photograph of the obtained adsorbent is shown in Figure 1. Using the above method, the number of adsorbents B fixed to adsorbent A was determined from the SEM photograph.

[0136] The adsorbent obtained above was formed into a sheet to produce an adsorption filter. The downstream layer was a thermal bonded nonwoven fabric, and the adsorbent obtained above and a thermoplastic powder resin as an adhesive were mixed in a weight ratio of 20:1. The resulting sheet had a basis weight of 200 g / m. ２ The adsorption filter was heated using an electret nonwoven fabric as the upstream layer, and an adsorption filter in which the adsorbent was supported on the nonwoven fabric was obtained. For this adsorption filter, the proportion of adsorbent B adhering to the surface of adsorbent A, the toluene removal rate, and the pressure loss were measured using the above-mentioned methods. The manufacturing conditions and measurement results of the adsorbent are shown in Table 2. Also, an SEM photograph taken after peeling off one side of the nonwoven fabric is shown in Figure 2.

[0137] Example 3 An adsorbent was obtained in the same manner as in Example 2, except that the weight ratio of adsorbent A to adsorbent B was changed to 50:1. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 2.

[0138] Example 4 An adsorbent was obtained in the same manner as in Example 2, except that the weight ratio of adsorbent A to adsorbent B was changed to 1:1. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 2.

[0139] Example 5 An adsorbent was obtained in the same manner as in Example 2, except that the weight ratio of adsorbent 1 to adsorbent B was changed to 1:2. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 2.

[0140] Example 6 An adsorbent was obtained in the same manner as in Example 2, except that the concentration of the aqueous sodium alginate (ALG-Na) solution mixed with the granular activated carbon and powdered activated carbon was changed to 9.0 wt%. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The manufacturing conditions and measurement results of the adsorbent are shown in Table 2.

[0141] Example 7 An adsorbent was obtained in the same manner as in Example 2, except that the concentration of the aqueous sodium alginate (ALG-Na) solution mixed with the granular activated carbon and powdered activated carbon was changed to 2.0 wt%. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 2.

[0142] Example 8 An adsorbent was obtained in the same manner as in Example 2, except that the molecular weight of sodium alginate (ALG-Na) mixed with the granular activated carbon and powdered activated carbon was changed to 80,000. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 2.

[0143] Example 9 An adsorbent was obtained in the same manner as in Example 2, except that the molecular weight of sodium alginate (ALG-Na) mixed with the granular activated carbon and powdered activated carbon was changed to 100,000. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 2.

[0144] Example 10 An adsorbent was obtained in the same manner as in Example 2, except that a 4.4 wt% aqueous solution of polyvinyl alcohol (PVA) was mixed with the granular activated carbon and powdered activated carbon instead of the aqueous solution of sodium alginate (ALG-Na). The molecular weight of the polyvinyl alcohol (PVA) was 90,000. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The manufacturing conditions and measurement results of the adsorbent are shown in Table 2.

[0145] Example 11 An adsorbent was obtained in the same manner as in Example 2, except that a 4.4 wt% aqueous polyacrylamide (PAM) solution was mixed with the granular activated carbon and powdered activated carbon instead of the aqueous sodium alginate (ALG-Na) solution. Furthermore, an adsorption filter was produced using the obtained adsorbent in the same manner as in Example 2. The manufacturing conditions and measurement results of the adsorbent are shown in Table 2.

[0146] Example 12 An adsorbent was obtained in the same manner as in Example 2, except that a 4.4 wt% aqueous solution of carboxymethyl cellulose (CMC) was mixed with the granular activated carbon and powdered activated carbon instead of the aqueous solution of sodium alginate (ALG-Na). The molecular weight of the carboxymethyl cellulose (CMC) was 120,000. An adsorption filter was also prepared using the obtained adsorbent in the same manner as in Example 2. The manufacturing conditions and measurement results of the adsorbent are shown in Table 2.

[0147] Example 13 An adsorbent was obtained in the same manner as in Example 2, except that a 4.4 wt% aqueous solution of polyvinylpyrrolidone (PVP) was mixed with the granular activated carbon and powdered activated carbon instead of the aqueous solution of sodium alginate (ALG-Na). The molecular weight of the polyvinylpyrrolidone (PVP) was 360,000. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The manufacturing conditions and measurement results of the adsorbent are shown in Table 2.

[0148] Example 14: Granular activated carbon (average particle length: 900 μm, specific surface area: 1000 m) was used as adsorbent A. ２ / g, pore volume 0.46 cm ３ An adsorbent was obtained in the same manner as in Example 2, except that adsorbent A and adsorbent B (wt. / g, average pore diameter 17 Å) were used and mixed in a weight ratio of 10:1. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 2.

[0149] Example 15: Powdered activated carbon (average particle length 50 μm, specific surface area 1000 m) was used as adsorbent B. ２ / g, pore volume 0.46 cm ３An adsorbent was obtained in the same manner as in Example 2, except that adsorbent A and adsorbent B (wt. / g, average pore diameter 17 Å) were used and mixed in a weight ratio of 2:1. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 2.

[0150] Example 16: Powdered activated carbon (average particle length 1 μm, specific surface area 1000 m) was used as adsorbent B. ２ / g, pore volume 0.46 cm ３ An adsorbent was obtained in the same manner as in Example 2, except that adsorbent A and adsorbent B (wt. / g, average pore diameter 17 Å) were used and mixed in a weight ratio of 100:1. An adsorption filter was also produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 2.

[0151]

[0152] Comparative Example 2: Granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) ２ / g, pore volume 0.46 cm ３ The adsorption filter was fabricated by forming a sheet of a thermo-bonded nonwoven fabric into a downstream layer. The adsorbent and a thermoplastic powder resin were mixed in a weight ratio of 20:1 to form a sheet with a basis weight of 200 g / m. ２ The adsorption filter was heated using an electret nonwoven fabric as the upstream layer, and the adsorption agent was supported on the nonwoven fabric to obtain an adsorption filter. The toluene removal rate and pressure loss of this adsorption filter were measured using the above-mentioned methods. The manufacturing conditions and measurement results of the adsorbent are shown in Table 3.

[0153] Comparative Example 3: Granular activated carbon (average particle length 900 μm, specific surface area 1000 m ２ / g, pore volume 0.46 cm ３ An adsorption filter was obtained in the same manner as in Comparative Example 2, except that a cellulose acetate stearate (cellulose acetate stearate, ...

[0154] Comparative Example 4: A thermal bond nonwoven fabric was used as the downstream layer, and granular activated carbon (average particle length: 600 μm, specific surface area: 1000 m) was used as the adsorbent A. ２ / g, pore volume 0.46 cm３ / g, average pore diameter 17 Å), and powdered activated carbon (average particle length 15 μm, specific surface area 1000 m) as adsorbent B. ２ / g, pore volume 0.46 cm ３ / g, average pore size 17 Å) and a thermoplastic powder resin as an adhesive in a weight ratio of 7:1:0.4 were mixed and used to prepare a 200 g / m ２ The adsorption filter was heated using an electret nonwoven fabric as the upstream layer, and an adsorption filter in which the adsorbent was supported on the nonwoven fabric was obtained. For this adsorption filter, the number of adsorbent B adhering to the surface of adsorbent A, the proportion of adsorbent B adhering to the surface of adsorbent A, the toluene removal rate, and the pressure loss were measured using the above-mentioned methods. The manufacturing conditions and measurement results are shown in Table 3. Also, an SEM photograph taken after peeling off one side of the nonwoven fabric is shown in Figure 3.

[0155] Comparative Example 5 An adsorbent was obtained in the same manner as in Example 2, except that the weight ratio of adsorbent A to adsorbent B was changed to 200:1. Using the above method, the number of adsorbent B particles adhering to adsorbent A was determined from SEM photographs. Furthermore, an adsorption filter was produced using the obtained adsorbent in the same manner as in Example 2. The production conditions and measurement results of the adsorbent are shown in Table 3.

[0156] Comparative Example 6: Granular activated carbon (average particle length 150 μm, specific surface area 1000 m ２ / g, pore volume 0.46 cm ３ The adsorption filter was fabricated by forming a sheet of a thermo-bonded nonwoven fabric into a downstream layer. The adsorbent and a thermoplastic powder resin were mixed in a weight ratio of 20:1 to form a sheet with a basis weight of 200 g / m. ２ The adsorption filter was heated using an electret nonwoven fabric as the upstream layer, and the adsorption agent was supported on the nonwoven fabric to obtain an adsorption filter. The toluene removal rate and pressure loss of this adsorption filter were measured using the above-mentioned methods. The manufacturing conditions and measurement results of the adsorbent are shown in Table 3.

[0157]

[0158] As can be seen from Table 2, the adsorbents of Examples 2 to 16 had a high toluene removal rate, and when the adsorbents were used to form an adsorption filter, the pressure loss was kept low.

[0159] In contrast, as can be seen from Table 3, Comparative Examples 2 and 3, in which adsorbent B was not used, showed low toluene removal rates. Comparative Example 4, in which adsorbent A and adsorbent B were mixed at a weight ratio of 7:1 but the proportion of adsorbent B adhering to the surface of adsorbent A was low, showed a high toluene removal rate, but the pressure loss of the adsorption filter was high. This is thought to be because the proportion of adsorbent B that was not adhering to adsorbent A and was free was high, causing clogging by filling the voids between the fibers of the nonwoven fabric. Comparative Example 5, in which adsorbent B was used but the weight ratio of adsorbent A to adsorbent B was 200:1, showed a low toluene removal rate due to the small amount of adsorbent B. Comparative Example 6, in which activated carbon with an average particle length of 150 μm, which does not correspond to adsorbent A or adsorbent B, was used alone, showed a high toluene removal rate, but the pressure loss when used as an adsorption filter was high.

[0160] Fig. 4 is a graph showing the relationship between the toluene removal rate and pressure loss when the adsorption filters were made using the adsorbents of Examples 1 to 16 and Comparative Examples 1 to 6. The horizontal axis represents pressure loss (mmAq), and the vertical axis represents the toluene removal rate (%). Fig. 4 shows that the filters using the adsorbents of Examples 1 to 16 had a high toluene removal rate relative to the pressure loss, while the filters using the adsorbents of Comparative Examples 1 to 6 had a low toluene removal rate relative to the pressure loss.

[0161] As described above, the adsorbent of the present invention has a high toluene removal rate and is capable of reducing the pressure loss when used in an adsorption filter.

[0162] Example 17: Silica gel (average particle length: 600 μm, specific surface area: 600 m) was used as adsorbent A. ２ / g, pore volume 0.46 cm ３ / g, average pore diameter 24 Å), and powdered activated carbon (average particle length 15 μm, specific surface area 1000 m) as adsorbent B. ２ / g, pore volume 0.46 cm ３The silica gel and powdered activated carbon (powdered activated carbon) were mixed in a weight ratio of 7:1, and an aqueous solution of sodium alginate (ALG-Na) was added in an amount of 0.46 times the total weight of the silica gel and powdered activated carbon. The molecular weight of the sodium alginate (ALG-Na) was 55,000, and the concentration of the aqueous solution of sodium alginate (ALG-Na) was 4.4 wt%. This was dried to obtain an adsorbent with powdered activated carbon adhered to the surface of the silica gel. Furthermore, an adsorption filter was produced using the obtained adsorbent in the same manner as in Example 2. The manufacturing conditions and measurement results of the adsorbent are shown in Table 4.

[0163] Comparative Example 7: Silica gel (average particle length: 600 μm, specific surface area: 600 m) was used instead of granular activated carbon. ２ / g, pore volume 0.46 cm ３ An adsorption filter was obtained in the same manner as in Comparative Example 2, except that an adsorbent having a molecular weight of 10 ...

[0164]

[0165] Fig. 5 is a graph showing the relationship between the toluene removal rate and pressure loss when adsorption filters were made using the adsorbents of Example 17, which used silica gel as adsorbent A, and Comparative Example 7. The horizontal axis represents pressure loss (mmAq), and the vertical axis represents toluene removal rate (%). From Table 4 and Fig. 5, it can be seen that the filter using the adsorbent of Example 17 had a high toluene removal rate relative to the pressure loss, while the filter using the adsorbent of Comparative Example 7 had a low toluene removal rate relative to the pressure loss. This shows that the effects of the present invention can be achieved by adhering adsorbent B to the surface of adsorbent A, regardless of the type of adsorbent.

[0166] Example 18: Electrostatically treated needle-punched nonwoven fabric (basis weight 30 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was applied to a sheet having a basis weight of 300 g / m ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0167] Example 19: Electrostatically treated needle-punched nonwoven fabric (basis weight 30 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0168] Example 20: Electrostatically treated needle-punched nonwoven fabric (basis weight 30 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0169] Example 21: Electrostatically treated needle-punched nonwoven fabric (basis weight 40 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0170] Example 22: Electrostatically treated needle-punched nonwoven fabric (basis weight 40 g / m ２), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0171] Example 23: Electrostatically treated needle-punched nonwoven fabric (basis weight 40 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0172] Example 24: Electrostatically treated needle-punched nonwoven fabric (basis weight 50 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0173] Example 25: Electrostatically treated needle-punched nonwoven fabric (basis weight 50 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0174] Example 26: Electrostatically treated needle-punched nonwoven fabric (basis weight 50 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0175] Example 27: Electrostatically treated needle-punched nonwoven fabric (basis weight 95 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0176] Example 28: Electrostatically treated needle-punched nonwoven fabric (basis weight 95 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0177] Example 29: Electrostatically treated needle-punched nonwoven fabric (basis weight 95 g / m ２), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0178] Example 30: Thermal bonded nonwoven fabric (basis weight 27 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0179] Example 31: Thermal bonded nonwoven fabric (basis weight 27 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0180] Example 32: Thermal bonded nonwoven fabric (basis weight 27 g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0181] Example 33: Electrostatically treated needle-punched nonwoven fabric (basis weight 30 g / m ２ ), granular activated carbon (average particle length 400 μm, specific surface area 1000 m ２ / g) and thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0182] Example 34: Electrostatically treated needle-punched nonwoven fabric (basis weight 30 g / m ２ ), granular activated carbon (average particle length 400 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0183] Example 35: Electrostatically treated needle-punched nonwoven fabric (basis weight 30 g / m ２ ), granular activated carbon (average particle length 400 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0184] Example 36: A PET thermal bonded nonwoven fabric (first layer basis weight 30 g / m) having a first layer made of a thermal bonded nonwoven fabric containing thermal adhesive staple fibers and a second layer made of a nonwoven fabric containing high melting point fibers having a melting point 30°C or more higher than the thermal adhesive staple fibers having the lowest melting point in the first layer. ２ , second layer basis weight 40g / m ２ , total basis weight 70g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, an electrostatically treated meltblown nonwoven fabric (basis weight 26 g / m ２ The adsorption filter was obtained by laminating two pieces of the adsorption filter (tensile strength of 3 N at a displacement of 3 mm) and integrating them by heat and pressure bonding. The physical properties of this adsorption filter were evaluated by the above-mentioned methods. The results are shown in Table 5.

[0185] Example 37: A PET thermal bonded nonwoven fabric (first layer basis weight 30 g / m) having a first layer made of a thermal bonded nonwoven fabric containing thermal adhesive staple fibers and a second layer made of a nonwoven fabric containing high melting point fibers having a melting point 30°C or more higher than the thermal adhesive staple fibers having the lowest melting point in the first layer. ２ , second layer basis weight 40g / m ２ , total basis weight 70g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, an electrostatically treated meltblown nonwoven fabric (basis weight 26 g / m ２ The adsorption filter was obtained by laminating two pieces of the adsorption filter (tensile strength of 3 N at a displacement of 3 mm) and integrating them by heat and pressure bonding. The physical properties of this adsorption filter were evaluated by the above-mentioned methods. The results are shown in Table 5.

[0186] Example 38: A PET thermal bonded nonwoven fabric (first layer basis weight 30 g / m) having a first layer made of a thermal bonded nonwoven fabric containing thermal adhesive staple fibers and a second layer made of a nonwoven fabric containing high melting point fibers having a melting point 30°C or more higher than the thermal adhesive staple fibers having the lowest melting point in the first layer. ２ , second layer basis weight 40g / m ２ , total basis weight 70g / m ２ ), granular activated carbon (average particle length 600 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, an electrostatically treated meltblown nonwoven fabric (basis weight 26 g / m ２ The adsorption filter was obtained by laminating two pieces of the adsorption filter (tensile strength of 3 N at a displacement of 3 mm) and integrating them by heat and pressure bonding. The physical properties of this adsorption filter were evaluated by the above-mentioned methods. The results are shown in Table 5.

[0187] <Comparative Example 8> Electrostatically processed needle-punched nonwoven fabric (basis weight 30 g / m ２ ), granular activated carbon (average particle length 250 μm, specific surface area 1000 m ２ / g) and thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0188] <Comparative Example 9> Electrostatically processed needle-punched nonwoven fabric (basis weight 30 g / m ２ ), granular activated carbon (average particle length 250 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0189] <Comparative Example 10> Electrostatically processed needle-punched nonwoven fabric (basis weight 30 g / m ２ ), granular activated carbon (average particle length 250 μm, specific surface area 1000 m ２ / g) and a thermoplastic powder resin were mixed in a weight ratio of 20:1, and the mixture was ２ On top of this, a thermal bond nonwoven fabric (65 g / m ２ The adsorption filter was then laminated and integrated by heat and pressure to obtain an adsorption filter. The physical properties of this adsorption filter were evaluated by the methods described above. The results are shown in Table 5.

[0190]

[0191] From Table 5, it can be seen that when the average particle length of activated carbon is 300 μm to 700 μm, the quality factor value is high and the pressure loss is low.

[0192] By using the adsorbent of the present invention, it is possible to remove pollutants including volatile organic compounds such as toluene and aldehydes efficiently with low pressure loss, which is expected to make a great contribution to the industrial world.

Claims

1. An adsorbent comprising an adsorbent A having an average particle length of 200 μm to 1000 μm and an adsorbent B having an average particle length of 0.1 μm to 100 μm, said adsorbent B being fixed to the surface of said adsorbent A, and the number of said adsorbents B fixed to each particle of said adsorbent A being 500 or more.

2. The average particle length R of the adsorbent A Ａ and the average particle major axis R of the adsorbent B Ｂ Ratio of R Ｂ / R Ａ The adsorbent according to claim 1, wherein the ratio of the solubility of the adsorbent to the total solubility of the adsorbent is 1 / 5000 to 1 / 5.

3. The average particle length R of the adsorbent A Ａ , the average particle major axis R of the adsorbent B Ｂ and the weight ratio P ((weight of adsorbent A) / (weight of adsorbent B)) of the adsorbent A and the adsorbent B is P=R Ａ ３ / [{(R Ａ +2R Ｂ ) ３ -R Ａ ３ 3. The adsorbent according to claim 1 or 2, which satisfies the relationship: x x, where x is 0.1 or more and 10 or less.

4. The adsorbent according to claim 1 or 2, wherein the adsorbent A is any one of activated carbon, activated alumina, silica gel, and zeolite.

5. The adsorbent according to claim 1 or 2, wherein the adsorbent B is any one of activated carbon, activated alumina, silica gel, and zeolite.

6. The adsorbent according to claim 1 or 2, wherein the adsorbent B is fixed to the surface of the adsorbent A via a binder.

7. The adsorbent according to claim 6, wherein the binder is at least one selected from the group consisting of sodium alginate, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyethylene glycol, polypropylene glycol, polyvinyl acetate, and copolymers thereof.

8. An adsorption filter comprising the adsorbent according to claim 1 or 2 and a substrate, wherein the adsorbent A and the adsorbent B are supported on the substrate, and when the total number of the adsorbents B is taken as 100%, 65% or more of the adsorbents B are fixed to the surface of the adsorbent A.

9. The adsorptive filter according to claim 8, wherein the substrate is a nonwoven fabric.

10. A method for producing an adsorbent, comprising the steps of: preparing an adsorbent A having an average particle length of 200 μm to 1000 μm, an adsorbent B having an average particle length of 0.1 μm to 100 μm, and a substrate; adsorbent B being fixed to the surface of the adsorbent A to obtain an adsorbent; and supporting the adsorbent on the substrate, wherein the weight W of the adsorbent A is Ａ and the weight W of the adsorbent B Ｂ Ratio of W Ａ / W Ｂ The value P is 0.3 or more and 150 or less, and when the total number of the adsorbents B is 100%, 65% or more of the adsorbents B are fixed to the surface of the adsorbent A.

11. The average particle length R of the adsorbent A Ａ and the average particle major axis R of the adsorbent B Ｂ Ratio of R Ｂ / R Ａ The method for manufacturing an adsorption filter according to claim 10, wherein the ratio of the number of particles to the number of particles is 1 / 5000 to 1 / 5.

12. The average particle length R of the adsorbent A Ａ , the average particle major axis R of the adsorbent B Ｂ , and the weight ratio P of the adsorbent A to the adsorbent B ((the weight W of the adsorbent A) Ａ ) / (weight W of adsorbent B Ｂ )) is P=R Ａ ３ / [{(R Ａ +2R Ｂ ) ３ -R Ａ ３ 12. The method for producing an adsorption filter according to claim 10, wherein the relationship: x x is 0.1 or more and 10 or less.

13. A method for manufacturing an adsorption filter as described in claim 10 or 11, wherein the step of fixing the adsorbent B to the surface of the adsorbent A to obtain an adsorbent includes a step of mixing the adsorbent A, the adsorbent B and a binder.

14. The method for manufacturing an adsorption filter according to claim 13, wherein the binder is at least one selected from the group consisting of sodium alginate, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyethylene glycol, polypropylene glycol, polyvinyl acetate, and copolymers thereof.

15. The method for manufacturing an adsorption filter according to claim 10 or 11, wherein the adsorbent A is any one of activated carbon, activated alumina, silica gel, and zeolite.

16. The method for manufacturing an adsorption filter according to claim 10 or 11, wherein the adsorbent B is any one of activated carbon, activated alumina, silica gel, and zeolite.

17. The method for manufacturing an adsorption filter according to claim 10 or 11, wherein the substrate is a nonwoven fabric.

18. An adsorption filter comprising at least a substrate A, an adsorption layer, and a substrate B laminated in the order listed, wherein the adsorption layer contains activated carbon, and the average particle length of the activated carbon is 300 μm to 700 μm.

19. The adsorption filter according to claim 18, which has a quality factor of 0.8 or more, as shown in the following formula: Quality factor = Ln {(100 - toluene deodorization efficiency [%]) / 100} / pressure loss of adsorption layer [mmAq] 20. An adsorption filter as claimed in claim 18 or 19, wherein the substrate A is a thermally bonded nonwoven fabric or a spunbonded nonwoven fabric.

21. An adsorptive filter according to claim 18 or 19, wherein the substrate B is a needle-punched nonwoven fabric, a thermally bonded nonwoven fabric, a melt-blown nonwoven fabric, or a spun-bonded nonwoven fabric.

22. A filter unit comprising an adsorption filter according to claim 18 or 19.

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