Adsorption filter

Abstract

To provide an adsorption filter that combines excellent water permeability through low water flow resistance with the capability to remove ultrafine particles, while allowing for extended use.SOLUTION: An adsorption filter according to the present invention is composed of a molded body including activated carbon and a binder. The pore volume of pores with diameters of 15-30 μm, relative to the volume of the adsorption filter and measured via mercury porosimetry, is 0.06-0.30 cm3 / cc.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an adsorption filter comprising a molded body containing activated carbon and a binder. [Background technology]

[0002] In recent years, there has been growing concern about the safety and health of tap water quality, and there is a desire to remove harmful substances contained in tap water, such as free residual chlorine, VOCs (volatile organic compounds) such as trihalomethanes, pesticides, and moldy odors.

[0003] In order to remove such harmful substances, an adsorption filter made of activated carbon molding is generally used.

[0004] It is desirable that the adsorption filter made of the activated carbon molded body also has the ability to remove turbidity components (particulate matter) contained in tap water. For this reason, for example, Patent Document 1 discloses a method for manufacturing a turbidity-reducing filter body that can be used for a longer period of time by adjusting the hardness difference between the inflow filter medium part and the outflow filter medium part of the activated carbon molded body. For example, Patent Document 2 discloses a water purification cartridge that is equipped with an activated carbon molded body and a nonwoven fabric and can achieve both high turbidity removal performance and a sufficiently long clogging life. Furthermore, for example, Patent Document 3 discloses an activated carbon molded body obtained by molding a mixture containing powdered activated carbon (a) and a fibrous binder (b) having a median particle size of 80 μm to 120 μm and a standard deviation σg in the particle size distribution of 1.3 to 1.9. It is described that the activated carbon molded body of Patent Document 3 has excellent removal capabilities for free residual chlorine, volatile organic compounds, CAT, and 2-MIB, and also has excellent turbidity filtering capabilities.

[0005] Generally, the turbidity removal performance test performed on activated carbon molded filters is specified, for example, in JIS S 3201:2019. In this test, kaolin of about 1 μm to 20 μm is used as the turbidity component (particulate matter) and its removal performance is evaluated. In the evaluations of activated carbon molded products in Patent Documents 1, 2, and 3, the turbidity removal performance is also evaluated based on this test.

[0006] Meanwhile, recently, from the viewpoint of further safety and hygiene, there has been a demand for adsorption filters made of activated carbon molded bodies that have the ability to remove not only fine particles (generally with a particle size of 1 μm to 20 μm) but also ultrafine particles with a particle size of 1 μm or less. As such an adsorption filter, for example, Patent Document 4 describes a molded adsorbent whose fine particle removal performance is improved by specifying the median particle size D50 of particulate matter and the content of particulate matter with a particle size of 10 μm or less within a predetermined range. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2015-033680 A [Patent Document 2] JP 2016-140788 A [Patent Document 3] International Publication No. 2011 / 016548 [Patent Document 4] Patent Publication No. 2021-122778 Summary of the Invention

[0008] An object of the present invention is to provide an adsorption filter which is capable of achieving both excellent water permeability due to low water resistance and ultrafine particle removal performance, and which can be used for a long period of time.

[0009] The present inventors conducted extensive research to solve the above problems and arrived at the present invention.

[0010] The adsorption filter according to a first aspect of the present invention is an adsorption filter made of a molded body containing activated carbon and a binder, The pore volume of the adsorption filter having a pore diameter of 15 μm or more and 30 μm or less is 0.06 cm3, as measured by mercury intrusion porosimetry. 3 / cc~0.30cm 3 / cc.

[0011] Alternatively, an adsorption filter according to a second aspect of the present invention is an adsorption filter made of a molded body containing activated carbon and a binder, In the volume-based cumulative particle size distribution of the activated carbon, D50 is 30 μm or more and 110 μm or less, and D90 is 110 μm or more, The content of particles having a particle diameter of 10 μm or less in the activated carbon is 1.2 vol % or more and 8.9 vol % or less. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing an example of a mold for preparing an adsorption filter in this embodiment. [Diagram 2] FIG. 2 is a perspective view showing an example of an adsorption filter according to this embodiment obtained using the mold of FIG. [Diagram 3] FIG. 3 is a diagram illustrating how to cut out a sample when measuring the pore volume of an adsorption filter. [Figure 4] FIG. 4 is a perspective view showing an example of an automatic grinding machine for manufacturing an adsorption filter. [Diagram 5] FIG. 5 is a graph showing the results of a water flow test using test water containing turbid substances in Examples 1 to 3 and Comparative Example 1. [Figure 6] FIG. 6 is a graph showing the results of a water flow test using test water containing turbid substances when backwashing was performed in Examples 1 to 3 and Comparative Example 1. [Figure 7] FIG. 7 is a graph showing the results of a water flow test using test water containing turbid substances in Examples 4 to 6. [Figure 8]FIG. 8 is a graph showing the results of a water flow test using test water containing turbid substances when backwashing was performed in Examples 4 to 6. [Figure 9] FIG. 9 is a graph showing the results of a water flow test using test water containing turbid substances in Comparative Examples 2 to 5. [Figure 10] FIG. 10 is a graph showing the results of a water flow test using test water containing turbid substances when backwashing was performed in Comparative Examples 2 to 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] As described above, the molded adsorbent described in Patent Document 4 has improved fine particle removal performance by defining the median particle diameter D50 of the particulate matter and the content of particulate matter with a particle diameter of 10 μm or less within a predetermined range. However, an adsorption filter with improved fine particle removal performance, particularly ultrafine particle removal performance, generally requires the particle size of the raw activated carbon to be finer to reduce the pores of the adsorption filter. This results in high water flow resistance of the adsorption filter. Therefore, there is a demand for an adsorption filter that can achieve both excellent water flow due to low water flow resistance and ultrafine particle removal performance.

[0014] In addition, it is considered that an adsorption filter made of finely grained activated carbon as a raw material, such as the molded adsorbent described in Patent Document 4, may become clogged early with turbid substances of about 1 μm to 20 μm, which may result in a decrease in the removal performance of the adsorption filter and a shortened life of the adsorption filter.

[0015] In order to extend the life of an adsorption filter, there is a method of reversing the water flow direction through the adsorption filter at regular intervals (also referred to as "backwashing" in this specification) to remove clogging caused by turbid substances. However, it is expected that an adsorption filter made of fine-grained activated carbon will not easily release turbid substances even when such a backwashing operation is performed.

[0016] According to the present invention, it is possible to provide an adsorption filter that can achieve both excellent water permeability due to low water resistance and ultrafine particle removal performance, and can be used for a long period of time. The adsorption filter according to the present invention can efficiently regenerate the flow rate by performing a backwashing operation, thereby extending the life of the filter.

[0017] Hereinafter, the embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0018] The adsorption filter in this embodiment is an adsorption filter made of a molded body containing activated carbon and a binder, and the pore volume of the adsorption filter having a pore diameter of 15 μm or more and 30 μm or less is 0.06 cm3 as measured by mercury intrusion porosimetry. 3 / cc~0.30cm 3 / cc.

[0019] Alternatively, the adsorption filter in this embodiment is an adsorption filter made of a molded body containing activated carbon and a binder, and in the volume-based cumulative particle size distribution of the activated carbon, D50 is 30 μm or more and 110 μm or less, D90 is 110 μm or more, and the particle content of the activated carbon having a particle diameter of 10 μm or less is 1.2 vol.% or more and 8.9 vol.% or less.

[0020] In this specification, "D50" means a 50% particle size in a cumulative particle size distribution based on volume. Furthermore, "D90" means a 90% particle size in a cumulative particle size distribution based on volume. Moreover, "D10" measured in the following examples means a 10% particle size in a cumulative particle size distribution based on volume.

[0021] By having any one of these configurations, the adsorption filter in this embodiment can achieve both excellent water permeability due to low water resistance and ultrafine particle removal performance, and can be used for a long period of time.

[0022] Specifically, in this embodiment, the physical properties and compounding ratio of the raw activated carbon are appropriately selected and / or adjusted, and the pore volume in the filter is appropriately controlled to adjust the pore volume in a predetermined pore diameter range to be within a specific range. Alternatively, in this embodiment, as the raw activated carbon, activated carbon is used in which D50 and D90 in the cumulative particle size distribution based on volume are within a predetermined range, and the content of particle diameters equal to or less than a specific value is within a predetermined range. As a result, an adsorption filter can be obtained that can achieve both excellent water permeability due to low water resistance and ultrafine particle removal performance, and can be used for a long period of time.

[0023] [Physical properties of adsorption filters] The adsorption filter in this embodiment has a pore volume of pores having a diameter of 15 μm or more and 30 μm or less based on the volume of the adsorption filter measured by mercury intrusion porosimetry (hereinafter, also simply referred to as "pore volume of pores having a diameter of 15 μm or more and 30 μm or less"). 3 / cc~0.30cm 3 / cc. The pore volume of pores with diameters of 15 μm to 30 μm is 0.06 cm 3 / cc or more, clogging due to turbid substances can be suppressed, and an adsorption filter having excellent water permeability and usable satisfactorily for a long period of time can be obtained. Furthermore, by performing a backwashing operation, the flow rate of the adsorption filter can be efficiently regenerated, and the life of the adsorption filter can be extended. In addition, when the pore volume of the pores having a diameter of 15 μm or more and 30 μm or less is reduced to 0.30 cm 3 By setting the content to be equal to or less than 1 / cc, the ultrafine particle removal performance of the adsorption filter can be improved.

[0024] The pore volume of the pores having a diameter of 15 μm or more and 30 μm or less is preferably 0.08 cm 3 / cc or more, preferably 0.10 cm 3 / cc or more, more preferably 0.12 cm 3 / cc or more, and 0.13 cm is particularly preferable. 3 The pore volume of the pores having a diameter of 15 μm or more and 30 μm or less is preferably 0.27 cm3 / cc or less, preferably 0.25 cm 3 / cc or less, and more preferably 0.23 cm 3 / cc or less, and especially preferably 0.21 cm 3 / cc or less.

[0025] Furthermore, the adsorption filter in this embodiment has a pore volume of pores with diameters of 7 μm or less based on the volume of the adsorption filter measured by mercury intrusion porosimetry (hereinafter, also simply referred to as "pore volume of pores with diameters of 7 μm or less") of 0.10 cm 3 The volume of pores with diameters of 7 μm or less is preferably 0.10 cm 3 / cc or more, the adsorption filter can obtain a significantly excellent ultrafine particle removal performance.

[0026] The pore volume of the pores having a diameter of 7 μm or less is more preferably 0.12 cm 3 / cc or more, more preferably 0.14 cm 3 The upper limit of the pore volume of the pores having a diameter of 7 μm or less is not particularly limited, but for example, the pore volume of the pores having a diameter of 7 μm or less is preferably 0.50 cm 3 / cc or less, preferably 0.45 cm 3 / cc or less, more preferably 0.40 cm 3 / cc or less.

[0027] Furthermore, the adsorption filter in this embodiment preferably has a total pore volume based on the volume of the adsorption filter measured by mercury intrusion porosimetry (hereinafter also simply referred to as "total pore volume") of 0.50 cm 3 / cc~0.73cm 3 / cc. The total pore volume is preferably 0.50 cm 3 By making the total pore volume 0.73 cm3 / cc or more, the adsorption filter can have better water permeability and can be suitably used for applications such as water purification filters. 3 By setting the amount of activated carbon to 0.1 g / cc or less, a sufficient amount of activated carbon can be retained, and the adsorption performance as a general filter can be improved.

[0028] The total pore volume is more preferably 0.53 cm 3 / cc or more, and more preferably 0.56 cm 3 The total pore volume is more preferably 0.70 cm3 / cc or more. 3 / cc or less, and more preferably 0.67 cm 3 / cc or less.

[0029] In this specification, the pore volume of pores with diameters of 15 μm to 30 μm, the pore volume of pores with diameters of 7 μm or less, and the total pore volume measured by mercury intrusion porosimetry can be measured using a mercury intrusion pore volume measuring device (MicroActive AutoPore V 9620 manufactured by Micromeritics Co., Ltd.) as described in the following examples. In the following examples, the molded layer of the filter is used as a measurement sample with a size of about 1 cm square, but it is preferable to change the size of this measurement sample appropriately depending on the filter size. For example, in the case of a spout-in type filter, it is desirable to measure with a measurement sample with a size of about 5 mm square.

[0030] In the adsorption filter of the present embodiment as described above, the pore volume with a pore diameter of 15 μm or more and 30 μm or less, the pore volume with a pore diameter of 7 μm or less, and the total pore volume can be controlled by various methods. For example, the values ​​can be controlled by appropriately selecting and / or adjusting the physical properties and the blending amount of the raw material activated carbon, the blending ratio of two or more types of activated carbon with different physical properties when used, the type and the blending amount of the raw material binder, the blending amount of the optional components of the raw material, the processing conditions (suction pressure, drying time, etc.) during the manufacture of the adsorption filter, etc. In particular, as will be described in detail later, the pore volume with a pore diameter of 15 μm or more and 30 μm or less can be controlled by adjusting the D50 and D90 of the raw material activated carbon and the particle content (volume %) of the raw material activated carbon with a particle diameter of 10 μm or less within a predetermined range.

[0031] The density of the adsorption filter in this embodiment (hereinafter also simply referred to as "filter density") is 0.59 g / cm 3 It is preferable that the filter density is 0.59 g / cm or less. 3 By keeping the density of the filter at 0.35 g / cm or less, the water resistance can be kept better, and the filter can be suitably used, for example, in a water purification filter. Also, clogging of the filter can be suppressed. Also, the filter density is 0.35 g / cm or less. 3 It is preferable that the filter density is 0.35 g / cm or more. 3 By setting the amount of activated carbon to the above level, the total amount of activated carbon becomes suitable, and the performance of removing ultrafine particles and other general harmful substances can be maintained at a good level.

[0032] The filter density is preferably 0.38 g / cm 3 More preferably, 0.40 g / cm 3 More preferably, 0.42 g / cm 3 More preferably, the filter density is 0.57 g / cm 3 More preferably, 0.55 g / cm 3 Less than 0.53 g / cm is particularly preferable. 3 In this specification, the filter density can be measured by the method described in detail in the Examples below.

[0033] The filter density can be controlled by various methods, for example, by appropriately selecting and / or adjusting the physical properties and amount of the raw activated carbon, the mixing ratio when two or more types of activated carbon with different physical properties are used, the type and amount of the raw binder, the amount of optional components in the raw material, the processing conditions (suction pressure, drying time, etc.) during the manufacture of the adsorption filter, etc.

[0034] The adsorption filter in this embodiment preferably has a benzene saturation adsorption amount of 18% to 35%. In this specification, the benzene saturation adsorption amount of the adsorption filter can be determined in accordance with the activated carbon test method of JIS K 1474:2014 by passing air containing solvent vapor at 1 / 10 the solvent saturation concentration at 25°C and calculating the increase in sample weight (%) when the mass becomes constant.

[0035] By setting the benzene saturation adsorption amount to 18% or more, sufficient removal performance can be obtained, particularly for organic substances. By setting the benzene saturation adsorption amount to 35% or less, it is possible to prevent the pore diameter from increasing in an overactivated state, and to suppress the risk of a decrease in the adsorption and retention capacity of harmful substances. The benzene saturation adsorption amount is more preferably 20% or more, and even more preferably 22% or more. Moreover, the benzene saturation adsorption amount is more preferably 33% or less, and even more preferably 30% or less.

[0036] The benzene saturation adsorption capacity of the adsorption filter in this embodiment can be controlled by, for example, appropriately selecting and / or adjusting the physical properties of the raw activated carbon and its blending amount, or, when two or more types of activated carbon with different physical properties are used, their blending ratio, etc.

[0037] [Composition of the adsorption filter] The adsorption filter in this embodiment is made of a molded body containing activated carbon and a binder.

[0038] (activated carbon) The activated carbon raw material used in the adsorption filter in this embodiment has a cumulative particle size distribution based on volume of the activated carbon, in which D50 is 30 μm or more and 110 μm or less, and D90 is 110 μm or more, and the content of particles having a particle size of 10 μm or less is 1.2 vol% or more and 8.9 vol% or less.

[0039] By using activated carbon with such a particle size as the raw material, the pore volume of pores with diameters of 15 μm to 30 μm is reduced to 0.06 cm 3 / cc~0.30cm 3 It is possible to obtain an adsorption filter having a size within the range of 1 / cc.

[0040] Specifically, by using activated carbon having a D50 of 30 μm or more and a D90 of 110 μm or more as the raw material activated carbon, the pore volume of the adsorption filter having a pore diameter of 15 μm or more and 30 μm or less can be increased. As a result, an adsorption filter that is less susceptible to clogging due to turbid substances, has excellent water permeability, and can be used well for a long period of time can be obtained. Furthermore, by performing a backwashing operation, the flow rate can be efficiently regenerated, and the life of the adsorption filter can be extended.

[0041] In the raw activated carbon, D50 is preferably 33 μm or more, more preferably 40 μm or more, even more preferably 44 μm or more, and particularly preferably 50 μm or more. In addition, in the raw activated carbon, D50 is preferably 108 μm or less, more preferably 100 μm or less, even more preferably 92 μm or less, and particularly preferably 85 μm or less.

[0042] In the raw material activated carbon, D90 is preferably 120 μm or more, more preferably 130 μm or more, even more preferably 140 μm or more, and particularly preferably 150 μm or more. The upper limit of D90 is not particularly limited, but may be, for example, 300 μm or less.

[0043] In addition, by making the content of particles with a particle diameter of 10 μm or less in the raw activated carbon 1.2% by volume or more, an adsorption filter with excellent ultrafine particle removal performance can be obtained. Furthermore, by making the content of particles with a particle diameter of 10 μm or less in the raw activated carbon 8.9% by volume or less, an adsorption filter with excellent water permeability due to low water permeability resistance can be obtained.

[0044] In the raw activated carbon, the content of particles having a particle diameter of 10 μm or less is preferably 2.7 vol% or more, more preferably 2.9 vol% or more, even more preferably 3.1 vol% or more, and particularly preferably 3.2 vol% or more. In addition, in the raw activated carbon, the content of particles having a particle diameter of 10 μm or less is preferably 8.0 vol% or less, more preferably 7.4 vol% or less, even more preferably 6.8 vol% or less, and particularly preferably 6.3 vol% or less.

[0045] The type of raw material activated carbon is not particularly limited as long as it satisfies the conditions of D50, D90 and the particle content of 10 μm or less in particle size, and it can be used alone or in combination of two or more types of activated carbon with different physical properties. When two or more types of activated carbon are used in combination, the particle content of 10 μm or less in particle size varies depending on the physical properties of each activated carbon and the blending ratio of each activated carbon. Therefore, the value can be controlled by appropriately selecting and / or adjusting them.

[0046] In this specification, the values ​​of D50, D90 and the particle content of the raw material activated carbon having a particle diameter of 10 μm or less can be controlled by appropriately selecting and / or adjusting, for example, the type of carbonaceous material that is the raw material of the activated carbon described later, the activation treatment method of the carbonaceous material during the production of the activated carbon and its treatment conditions (heating temperature and time, etc.), the crushing conditions, the classification conditions, etc. Furthermore, the D50, D90 and the particle content of the raw material activated carbon having a particle diameter of 10 μm or less can be analyzed and measured, for example, by a laser diffraction / scattering method using a wet particle size distribution measuring device (Microtrac MT3300EX-II, manufactured by Microtrac-Bell, Inc.) as described in the examples described later.

[0047] The raw activated carbon may be a commercially available product. Alternatively, for example, activated carbon obtained by subjecting a carbonaceous material serving as a raw material for the activated carbon to a carbonization treatment as necessary, followed by an activation treatment, and, as necessary, a washing treatment, a drying treatment, and a pulverization treatment, may be used.

[0048] The carbonaceous material to be used as the raw material is not particularly limited, but examples thereof include plant-based carbonaceous materials (e.g., plant-derived materials such as wood, sawdust, charcoal, fruit shells such as coconut shells and walnut shells, fruit seeds, pulp manufacturing by-products, lignin, and blackstrap molasses), mineral-based carbonaceous materials (e.g., mineral-derived materials such as peat, lignite, brown coal, bituminous coal, anthracite, coke, coal tar, coal pitch, petroleum distillation residue, and petroleum pitch), synthetic resin-based carbonaceous materials (e.g., synthetic resin-derived materials such as phenolic resin, polyvinylidene chloride, and acrylic resin), and natural fiber-based carbonaceous materials (e.g., natural fibers such as cellulose, and regenerated fibers such as rayon). These carbonaceous materials may be used alone or in combination of two or more.

[0049] Among these carbonaceous materials, coconut shells or phenolic resins are preferred from the viewpoint of ease of development of micropores involved in the volatile organic compound removal performance defined in JIS S 3201:2019.

[0050] When carbonization is required, these carbonaceous materials can be usually subjected to carbonization in an environment that is blocked from oxygen or air, for example, at a temperature of about 400° C. to 800° C., preferably 500° C. to 800° C., and more preferably 550° C. to 750° C. Thereafter, particle size adjustment may be performed as necessary.

[0051] Thereafter, the carbonaceous material is subjected to an activation treatment. The activation treatment is a treatment in which pores are formed on the surface of the carbonaceous material to convert it into activated carbon, which is a porous body. The activation treatment can be performed by a method generally used in the technical field, and is not particularly limited. Two types of treatment methods, gas activation treatment and chemical activation treatment, can be mentioned mainly. Of these, when used for water purification treatment, gas activation treatment is preferred from the viewpoint of leaving less impurities.

[0052] The gas activation treatment is, for example, a treatment in which the carbonaceous material is heated in the presence of water vapor, carbon dioxide, air, oxygen, combustion gas, or a mixed gas thereof. The heating temperature is not particularly limited, but is, for example, performed at a temperature of about 700°C to 1100°C, preferably 800°C to 980°C, and more preferably 850°C to 950°C. The activation time and the temperature rise rate are not particularly limited, and may be appropriately adjusted according to the type, shape, and size of the selected carbonaceous material. In consideration of safety and reactivity, it is preferable to perform the treatment using a water vapor-containing gas containing water vapor at 10% by volume to 40% by volume. The chemical activation treatment may be performed by a known method in which, for example, an activator such as zinc chloride, calcium chloride, phosphoric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, magnesium hydroxide, or calcium hydroxide is mixed with the carbonaceous material and heated under an inert gas atmosphere.

[0053] The activated carbon after the activation treatment is washed and dried as necessary. Specifically, when a plant-based carbonaceous material such as coconut shell or a mineral-based carbonaceous material containing impurities such as alkali metals, alkaline earth metals, and transition metals is used as the raw material for the activated carbon, washing is performed as necessary to remove ash, chemicals, etc. Mineral acid and water are used for washing, and hydrochloric acid, which has a high washing efficiency, is preferred as the mineral acid.

[0054] The activated carbon after the activation treatment is pulverized and / or classified as necessary. The pulverization can be performed using a pulverizing device generally used for pulverizing activated carbon, such as an aerofoil mill, a rod mill, a roller mill, a hammer mill, a blade mill, a pin mill, or other high-speed rotating mill, a ball mill, a jet mill, or the like. The classification can be performed using a method generally used for classifying activated carbon, such as classification using a sieve, wet classification, or dry classification. Examples of wet classifiers include classifiers that utilize the principles of gravity classification, inertial classification, hydraulic classification, centrifugal classification, or the like. Examples of dry classifiers include classifiers that utilize the principles of sedimentation classification, mechanical classification, centrifugal classification, or the like.

[0055] The form of the activated carbon obtained through such a treatment or commercially available activated carbon may be any of powder, particles, fibers (fibers, woven fabric (cloth), felt), etc., and can be appropriately selected depending on the application. Among these forms, powder, which has high adsorption performance per volume, is preferred.

[0056] (binder) The binder used in the adsorption filter in this embodiment is not particularly limited, and a powder or fibrous binder may be used alone or in combination of two or more. Among these, it is preferable to use a fibrous binder from the viewpoint of excellent water permeability when the adsorption filter is molded.

[0057] The fibrous binder is not particularly limited as long as it can be shaped by entangling activated carbon, and can be widely used regardless of synthetic or natural products. Examples of such binders include acrylic fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, cellulose fibers, nylon fibers, aramid fibers, and pulp. The fiber length of the fibrous binder is preferably 4 mm or less.

[0058] It is preferable that the fibrous binder contains an acrylic fibrous binder. Furthermore, it is more preferable that the fibrous binder contains a cellulose fibrous binder. Moreover, these fibrous binders may be used in combination of two or more kinds. For example, it is more preferable to use both an acrylic fibrous binder and a cellulose fibrous binder in combination. By using a combination of cellulose fibrous binders, it is possible to reduce the outflow of fine powder from the adsorption filter in this embodiment. The blending ratio of the acrylic fibrous binder and the cellulose fibrous binder is preferably 30 parts by mass to 70 parts by mass, more preferably 40 parts by mass to 60 parts by mass, of the cellulose fibrous binder relative to 100 parts by mass of the acrylic fibrous binder.

[0059] In this embodiment, the water permeability of the fibrous binder is preferably about 1 mL to 200 mL in terms of CSF value. More preferably, the CSF value is 10 mL to 150 mL. Here, in this specification, the CSF value is a value measured with reference to the Canadian standard freeness method of "Testing method for freeness of pulp" specified in JIS P 8121:2012. Specifically, the value is evaluated using tap water with a conductivity of about 100 μs / cm in the measurement. The CSF value can be adjusted, for example, by fibrillating the binder.

[0060] By setting the CSF value of the fibrous binder to 1 mL or more, sufficient water permeability can be maintained, the strength of the molded body can be prevented from decreasing, and the risk of pressure loss can be prevented. Furthermore, by setting the CSF value to 200 mL or less, powdered activated carbon can be sufficiently retained, the strength of the molded body can be prevented from decreasing, and the risk of the adsorption performance can be prevented from decreasing. When two or more types of fibrous binders are used in combination, it is preferable that the CSF value of the two or more types of fibrous binders mixed together satisfies the above range.

[0061] Specifically, when the fibrous binder contains an acrylic fibrous binder, the CSF value of the acrylic fibrous binder is preferably 20 mL or more, more preferably 50 mL or more. The CSF value of the acrylic fibrous binder is preferably 200 mL or less, more preferably 150 mL or less. By setting the CSF value in such a range, even when the fibrous binder contains a fibrous binder other than the acrylic fibrous binder, the CSF value of the entire fibrous binder containing the acrylic fibrous binder becomes an appropriate value, which makes it possible to improve the strength of the molded body, reduce pressure loss, and maintain the retention and adsorption performance of the powdered activated carbon. From the same viewpoint, when the fibrous binder contains an acrylic fibrous binder and a cellulose fibrous binder, the cellulose fibrous binder preferably has a CSF value of 1 mL or more, more preferably 10 mL or more, when 50 parts by mass of the cellulose fibrous binder are mixed with 100 parts by mass of the acrylic fibrous binder. The cellulose-based fibrous binder preferably has a CSF value of 50 mL or less, and more preferably 40 mL or less, when 50 parts by mass of the cellulose-based fibrous binder is mixed with 100 parts by mass of the acrylic fibrous binder.

[0062] The blending ratio of the activated carbon and the binder is not particularly limited, and may be appropriately set so that the pore volume of the pores having a diameter of 15 μm or more and 30 μm or less (and preferably the pore volume of the pores having a diameter of 7 μm or less) falls within the specific range specified in this embodiment when the adsorption filter is molded. For example, taking into consideration the adsorption performance of the activated carbon and the moldability of the adsorption filter, the binder is preferably about 2 to 8 parts by mass per 100 parts by mass of the activated carbon. By setting the amount of the binder to 2 parts by mass or more, a molded adsorption filter having sufficient strength can be obtained. By setting the amount of the binder to 8 parts by mass or less, it is possible to suppress the adsorption performance of the activated carbon in the adsorption filter from decreasing.

[0063] The mixing ratio of the binder to 100 parts by mass of activated carbon is more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more. The mixing ratio of the binder to 100 parts by mass of activated carbon is more preferably 7 parts by mass or less, and even more preferably 6 parts by mass or less. In addition, when the binder contains a lead adsorbent or the like described later, it is preferable that the mixing ratio of the binder is the above-mentioned mixing ratio with respect to the total of the activated carbon and the lead adsorbent.

[0064] (optional ingredient) Furthermore, the adsorption filter in this embodiment may contain any other functional component as long as the effect of the present invention is not impaired. For example, zeolite powder (lead adsorbent), ion exchange resin, or chelating resin that can adsorb and remove soluble lead may be included. Furthermore, in order to impart antibacterial properties, various adsorbents containing silver ions or silver compounds may be included alone or in combination of two or more. An example of such an adsorbent is silver-impregnated activated carbon, which is added in an amount that does not affect the physical properties of the adsorption filter in this embodiment. The amount of these other optional components is not particularly limited, but may be appropriately set so that the pore volume of a pore diameter of 15 μm to 30 μm (and preferably the pore volume of a pore diameter of 7 μm or less) falls within the specific range specified in this embodiment when the adsorption filter is molded. For example, 1 to 30 parts by mass of the other optional components may be added to 100 parts by mass of the entire adsorption filter.

[0065] The adsorption filter made of a molded body containing activated carbon and a binder in this embodiment may further include a core and may be a cylindrical adsorption filter. By making it cylindrical, the water flow resistance can be reduced. Furthermore, when it is filled into a housing and used as a cartridge as described below, there is an advantage that the cartridge can be easily loaded into a water purifier and replaced.

[0066] The core is not particularly limited as long as it can be inserted into the hollow part of the cylindrical adsorption filter and can reinforce the cylindrical adsorption filter. Examples include trical pipes, netron pipes, ceramic filters, etc. Furthermore, nonwoven fabrics can be wrapped around the outer periphery of the core.

[0067] [Method of manufacturing adsorption filters] The method for producing the adsorption filter in this embodiment is not particularly limited and may be any method known to those skilled in the art. From the viewpoint of efficient production, the slurry suction method is preferred.

[0068] An example of a method for producing a cylindrical adsorption filter in this embodiment will be described in detail below, but the present invention is not limited to this production method.

[0069] Specifically, for example, the cylindrical adsorptive filter (molded body) in this embodiment can be manufactured by a method including a slurry preparation step, a suction filtration step, a rolling step as required, a drying step, and a grinding step as required. In the slurry preparation step, powdered activated carbon and a fibrous binder are dispersed in water to prepare a slurry. In the suction filtration step, the prepared slurry is filtered while being sucked to obtain a premolded body. In the rolling step, the premolded body after suction filtration is compressed on a shaping table to adjust the shape of the outer surface as required. In the drying step, the premolded body with the adjusted shape is dried to obtain a dried molded body. In the grinding step, the outer surface of the dried molded body is ground as required. Each step will be described in more detail below.

[0070] (Slurry preparation process) In the slurry preparation step, a slurry is prepared by dispersing the powdered activated carbon and the fibrous binder in a solvent, for example, so that the fibrous binder is 2 to 8 parts by mass relative to 100 parts by mass of the powdered activated carbon, and the solid content concentration is 0.1 to 10% by mass, preferably 1 to 5% by mass. The solvent is not particularly limited, but it is preferable to use water or the like. By adjusting the solid content concentration of the slurry to a concentration that is not too high, the dispersion can be easily made uniform, and the occurrence of spots in the molded body can be prevented. On the other hand, by adjusting the solid content concentration of the slurry to a concentration that is not too low, the molding time can be shortened, and the productivity can be improved. Furthermore, the density of the molded body can be prevented from becoming too high, and good water permeability can be maintained.

[0071] (Suction filtration process) The suction filtration process will be described with reference to FIG. 1. In FIG. 1, the respective symbols represent a mold 1, a core 2, a suction hole 3, flanges 4, 4', and a filtrate outlet 5. In the suction filtration process, for example, as shown in FIG. 1, a mold 1 for a cylindrical molded body is used, which has a number of suction holes 3 on the surface of a core 2, flanges 4, 4' attached to both ends, and a filtrate outlet 5. First, the above-mentioned core is attached to the mold 1, and the mold 1 is placed in the prepared slurry, and the slurry is attached to the mold 1 by filtering while sucking from the inside of the mold 1 through the filtrate outlet 5. As a suction method, a conventional method, for example, a method of sucking using a suction pump or the like, can be used. In this way, the preform is attached to the mold 1.

[0072] (Rolling process) If necessary, after the suction filtration step, a rolling step can be carried out in order to adjust the outer diameter of the preform to a predetermined size, to increase the roundness, and to reduce the unevenness of the outer peripheral surface. In the rolling step, the mold 1 with the preform obtained in the suction filtration step still attached thereto is placed on a table and moved back and forth while being pressed down with a predetermined force.

[0073] The suction filtration step and the rolling step, which are performed as necessary, may be performed any number of times in order to obtain the desired pore volume, adsorption filter density, and the like.

[0074] (drying process) Next, the flanges 4, 4' at both ends of the mold 1 are removed, and the core 2 is pulled out. This makes it possible to obtain a hollow cylindrical preform. In the drying step, the preform thus removed from the mold 1 is dried in a dryer or the like to obtain the molded body 6 (the adsorption filter in this embodiment) shown in Fig. 2.

[0075] The drying temperature is, for example, about 100°C to 150°C, particularly about 110°C to 130°C. The drying time is, for example, about 4 to 24 hours, particularly about 8 to 16 hours. By setting the drying temperature at a temperature that is not too high, it is possible to prevent deterioration of the filtration performance or deterioration of the strength of the molded body due to deterioration or melting of the fibrous binder. By setting the drying temperature at a temperature that is not too low, it is possible to shorten the drying time and prevent insufficient drying.

[0076] (Grinding process) If necessary, after the drying step, a grinding step can be performed to further adjust the outer diameter of the adsorption filter or to reduce the unevenness of the outer peripheral surface. The grinding method is not particularly limited as long as it can grind (or polish) the outer surface of the dried molded body, and any grinding method known to those skilled in the art can be used. From the viewpoint of uniformity of grinding, a method using a grinding machine that rotates and grinds the molded body itself is preferred.

[0077] The grinding step is not limited to a method using a grinding machine, and may be performed, for example, by grinding a molded body fixed to a rotating shaft with a fixed flat grinding wheel. In this method, the generated grinding swarf tends to accumulate on the grinding surface, so it is effective to perform grinding while blowing air.

[0078] [Uses of adsorption filters] The adsorption filter in this embodiment can be used, for example, as a water purification filter, a filter for artificial dialysis, etc. When used as a water purification filter or a filter for artificial dialysis, for example, the adsorption filter can be manufactured by the above-mentioned manufacturing method, shaped and dried, and then cut into a desired size and shape for use. Furthermore, if necessary, a cap may be attached to the tip portion, or a nonwoven fabric may be attached to the surface.

[0079] The adsorption filter in this embodiment can be filled in a housing and used as a water purification cartridge. The water purification cartridge is loaded into a water purifier and used to pass water, and the water passing method can be a total filtration method in which the entire amount of raw water is filtered or a circulation filtration method. The water purification cartridge loaded into the water purifier can be used, for example, by filling a water purification filter (the adsorption filter in this embodiment) into a housing. Alternatively, the water purification filter can be used in combination with a known nonwoven fabric filter, various adsorbents, mineral additives, ceramic filter materials, etc.

[0080] The outline of the present invention has been described above, but the adsorption filter in this embodiment can be summarized as follows.

[0081] The adsorption filter according to a first aspect of the present invention is an adsorption filter made of a molded body containing activated carbon and a binder, The pore volume of the adsorption filter having a pore diameter of 15 μm or more and 30 μm or less is 0.06 cm3, as measured by mercury intrusion porosimetry. 3 / cc~0.30cm 3 / cc.

[0082] Alternatively, an adsorption filter according to a second aspect of the present invention is an adsorption filter made of a molded body containing activated carbon and a binder, In the volume-based cumulative particle size distribution of the activated carbon, D50 is 30 μm or more and 110 μm or less, and D90 is 110 μm or more, The content of particles having a particle diameter of 10 μm or less in the activated carbon is 1.2 vol % or more and 8.9 vol % or less.

[0083] In the adsorption filter according to the first or second aspect, the volume of pores having a diameter of 7 μm or less on a volume basis of the adsorption filter as measured by mercury intrusion porosimetry is 0.10 cm 3 It is preferable that the content is 1 / cc or more.

[0084] In the adsorption filter according to the first aspect, in a cumulative particle size distribution based on volume of the activated carbon, D50 is 30 μm or more and 110 μm or less, and D90 is 110 μm or more, The content of particles having a particle diameter of 10 μm or less in the activated carbon is preferably 1.2% by volume or more and 8.9% by volume or less. EXAMPLES

[0085] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0086] First, the raw materials used in each Example and Comparative Example, the methods for measuring the physical properties of the raw material powdered activated carbon, and the methods for measuring and evaluating the physical properties of the produced adsorption filters will be described in detail.

[0087] [Raw materials for adsorption filters] The method for producing the activated carbon (powdered activated carbon) used as the raw material will be described below, but the production method is not particularly limited as long as it satisfies the required physical properties.

[0088] Powdered activated carbon A Coconut shell charcoal made by carbonizing coconut shells from the Philippines was activated with steam at 900°C, and the obtained coconut shell activated carbon was washed with dilute hydrochloric acid and desalted with ion-exchanged water to obtain granular activated carbon. The obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon A with D10 of 15 μm, D50 of 85 μm, and D90 of 159 μm.

[0089] ·Powdered activated carbon B Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon B having a D10 of 14 μm, a D50 of 60 μm, and a D90 of 152 μm.

[0090] ·Powdered activated carbon C Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon C having a D10 of 18 μm, a D50 of 55 μm, and a D90 of 152 μm.

[0091] ·Powdered activated carbon D Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon D having a D10 of 15 μm, a D50 of 86 μm, and a D90 of 164 μm.

[0092] Powdered activated carbon E Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon E having a D10 of 18 μm, a D50 of 45 μm, and a D90 of 130 μm.

[0093] ·Powdered activated carbon F Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon F having a D10 of 18 μm, a D50 of 44 μm, and a D90 of 120 μm.

[0094] ·Powdered activated carbon G Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon G having a D10 of 16 μm, a D50 of 32 μm, and a D90 of 58 μm.

[0095] ·Powdered activated carbon H Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon H having a D10 of 13 μm, a D50 of 108 μm, and a D90 of 194 μm.

[0096] ·Powdered activated carbon I Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a roll mill to obtain powdered activated carbon I having a D10 of 72 μm, a D50 of 138 μm, and a D90 of 215 μm.

[0097] ·Powdered activated carbon J Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill and then dry classified. Finally, powdered activated carbon J with D10 of 24 μm, D50 of 58 μm, and D90 of 149 μm was obtained.

[0098] ·Powdered activated carbon K Granular activated carbon was obtained in the same manner as for powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon K having a D10 of 10 μm, a D50 of 32 μm, and a D90 of 66 μm.

[0099] The physical properties of the above powdered activated carbon A to powdered activated carbon K are summarized in Tables 3 and 4 below, together with the physical properties of the adsorption filters and the evaluation results thereof.

[0100] (binder) Acrylic fibrous binder: "Acrylic fiber Bi-PUL / F" manufactured by Nippon Exlan Kogyo Co., Ltd., CSF value 83mL Cellulosic fibrous binder (CSF value is 28 mL when 50 parts by mass of the cellulose fibrous binder is mixed with 100 parts by mass of the above acrylic fibrous binder (CSF value 83 mL))

[0101] (others) Titanosilicate lead adsorbent: Solenis, "ATS", average particle size 20μm Core: Daiwabo Progress Co., Ltd., "PMF-30C-12-14" Nonwoven fabric: Shinwa Co., Ltd., "9540-F"

[0102] [Measurement of particle size distribution of raw activated carbon] The D10 (μm), D50 (μm), and D90 (μm) of the raw material activated carbon, as well as the particle content (volume %) with a particle diameter of 10 μm or less, were measured by the laser diffraction / scattering method. That is, the activated carbon to be measured was placed in ion-exchanged water together with a surfactant, and ultrasonic vibration was applied to create a uniform dispersion, which was then measured using a wet particle size distribution analyzer (Microtrac MT3300EX-II, manufactured by Microtrac-Bell). The surfactant used was "Polyoxyethylene (10) octylphenyl ether" manufactured by Fujifilm Wako Pure Chemical Corporation. The analysis conditions are shown below.

[0103] (Analysis conditions) Number of measurements: Average of 3 measurements Measurement time: 30 seconds Distribution display; volume Particle size classification; standard Calculation mode: MT3000II Solvent name;WATER Upper measurement limit: 2000μm, lower measurement limit: 0.021μm Remaining ratio: 0.00 Passage ratio: 0.00 Remaining ratio setting; Disabled Particle permeability; absorption Particle refractive index: N / A Particle shape;N / A Solvent refractive index: 1.333 DV value: 0.0882 Transmittance (TR);0.880~0.900 Enhanced Filter; Disabled Flow rate;70% Ultrasonic output: 40W Ultrasonic time: 180 seconds

[0104] [Measurement of adsorption filter density] Adsorption filter density (g / cm 3 ) was calculated according to the following formula after drying the obtained adsorption filter at 120° C. for 2 hours. Note that the adsorption filter density refers to the density of only the molded layer of activated carbon. Adsorption filter density = (mass of the activated carbon adsorption filter layer) / (volume of the activated carbon adsorption filter layer)

[0105] [Measuring the pore volume of adsorption filters using a mercury porosimeter] The pore volume of the adsorption filter was measured using a mercury intrusion pore volume measuring device (MicroActive AutoPore V 9620, manufactured by Micromeritics). The measurement pressure was 0.7 kPa-420 MPa. After cutting out the molded layer consisting of activated carbon and binder of the cylindrical adsorption filter as shown in Figure 3, the cut piece was further cut into a size of approximately 1 cm square. The pore volume (cm) of the cut out sample of approximately 1 cm square with a pore diameter of 15 μm to 30 μm based on the weight of the adsorption filter was 3 / g), pore volume of pores with diameters of 7 μm or less (cm 3 / g) and total pore volume (cm 3 The pore volume (cm3) of the adsorption filter with a pore diameter of 15 μm or more and 30 μm or less was calculated by multiplying these values ​​by the adsorption filter density obtained above. 3 / cc), pore volume of pores with diameters of 7 μm or less (cm 3 / cc) and total pore volume (cm 3 / cc) was calculated.

[0106] [Evaluation of turbidity filtering capacity] The turbidity filtering capacity of the adsorption filter was evaluated by conducting a water flow test using test water containing turbidity substances and calculating the turbidity removal rate life (L / cc) and turbidity clogging life (L / cc). These were measured and calculated using the following methods.

[0107] First, kaolin (manufactured by Nacalai Tesque, Inc.) with a particle size of 0.1 μm to 4 μm was used as a turbid substance, and the dilution water adjusted to a turbidity of 2 degrees was adjusted to a water temperature of 20 ± 3 ° C., which was used as the test water. This test water was passed through the obtained cylindrical adsorption filter from the outside to the inside so that the dynamic water pressure was maintained at 0.1 MPa, and the flow rate was measured over time. At the same time, the test water and the treated water were collected and used as samples. These samples were measured for turbidity at a wavelength of 660 nm using a spectrophotometer (manufactured by SHIMADZU, "UV-1900") and a cylindrical quartz cell of 50 mm. From the results, the removal rate (%) of turbidity contained in the test water by the treatment was calculated. Furthermore, the cumulative amount of water passing per volume of the adsorption filter at the time when the turbidity removal rate became less than 80% was calculated as the turbidity removal rate life (L / cc). In this test, a turbidity removal rate life (L / cc) of 10.5 L / cc or more was set as the passing standard, and the adsorption filter was evaluated as being capable of effectively removing turbid substances over a long period of time.

[0108] Furthermore, the cumulative amount of water passing per volume of the adsorption filter when the flow rate became less than half of that after 10 minutes of water passing was calculated as the turbidity clogging life (L / cc). In this test, a turbidity clogging life (L / cc) of 10.5 L / cc or more was regarded as the passing standard, and the adsorption filter was evaluated as being able to maintain excellent water permeability for a long period of time without clogging with turbid substances.

[0109] [Evaluation of turbidity substance filtration capacity when performing backwashing] The turbidity filtering capacity of the adsorption filter during backwashing was evaluated by the following method. While backwashing was being performed, a water flow test was conducted using test water containing turbidity substances, and the turbidity removal rate life (L / cc) and turbidity clogging life (L / cc) were calculated. These were measured and calculated by the following method.

[0110] Backwashing was performed once every 5 hours of water flow from the start of the water flow test. Specifically, the backwashing was performed by reversing the water flow direction for 1 minute, i.e., passing the test water from the inside to the outside of the cylindrical adsorption filter while maintaining a dynamic water pressure of 0.1 MPa. After 1 minute had elapsed, the water flow direction was returned to the original direction, i.e., the test water was passed again from the outside to the inside of the adsorption filter while maintaining a dynamic water pressure of 0.1 MPa. Other procedures, measurement methods, and calculation methods were the same as those for the turbidity removal rate life (L / cc) and turbidity clogging life (L / cc) described above.

[0111] In this test, the pass criterion was a turbidity removal rate life (L / cc) of 15.1 L / cc or more when backwashing was performed, and the adsorption filter was evaluated as being able to effectively remove turbid substances for a long period of time while backwashing was performed.In addition, the pass criterion was a turbidity clogging life (L / cc) of 15.1 L / cc or more when backwashing was performed, and the adsorption filter was evaluated as being able to maintain excellent water permeability for a long period of time while backwashing was performed without clogging with turbid substances.

[0112] [Measurement of ultrafine particle removal performance] The ultrafine particle removal performance of the adsorption filter was measured by the following method. First, using fluorescent particles Fluoro-Max™ Green Fluorescent Polymer Microspheres G500 (particle diameter 0.5 μm) manufactured by Thermo Fisher Scientific, diluted water with a concentration of 10,000 particles / ml or more was prepared, and the temperature of the diluted water was adjusted to 20±3°C to prepare test water. This test water was passed from the outside to the inside of the cylindrical adsorption filter at a flow rate of 1.9 L / min, and the test water and treated water were simultaneously collected over time to prepare samples. These samples were filtered through a 0.2 μm membrane filter (MEMBRANE FILTER A020B025A WHITE (cellulose mixed ester, 0.2 μm, 25 mm, black ruled) manufactured by ADVANTEC), and the membrane filter was dried at 60°C. The dried membrane filter was fixed on a slide glass and observed under a fluorescent microscope (OLYMPUS, "BX51-34-FL") to calculate the number of fluorescent particles in both samples, and the removal rate (%) of particles contained in the test water by treatment was calculated. Furthermore, the cumulative amount of water passing per volume of the adsorption filter at the time when the particle removal rate became less than 85% was calculated as the ultrafine particle removal rate life (L / cc). In this test, the pass criterion was an ultrafine particle removal rate life (L / cc) of 10.5 L / cc or more, and the adsorption filter was evaluated as being capable of removing ultrafine particles well for a long period of time.

[0113] [Measurement of initial water flow resistance] Water at 20±3°C was passed from the outside to the inside of the cylindrical adsorption filter at a flow rate of 1.9 L / min, and the water flow resistance (MPa) 10 minutes after the start of water flow was measured as the initial water flow resistance (MPa). Note that this water flow resistance value did not include the resistance due to the housing.

[0114] [Measurement of VOC removal performance] The VOC removal performance of the adsorption filter was measured by the following method. First, diluted water with a chloroform concentration of 60±12 ppb was prepared, and the temperature of the diluted water was adjusted to 20±3°C to prepare test water. This test water was passed from the outside to the inside of the cylindrical adsorption filter at a flow rate of 1.9 L / min, and the test water and treated water were simultaneously collected over time to prepare samples. The chloroform concentration in these samples was measured using an ECD gas chromatograph ("GC-2014", manufactured by Shimadzu Corporation), and the removal rate (%) was calculated. Furthermore, the cumulative amount of water passing per volume of the adsorption filter at the time when the chloroform removal rate became less than 80% was calculated as the VOC removal rate life (L / cc). In this test, a VOC removal rate life (L / cc) of 10.5 L / cc or more was used as the pass criterion, and the adsorption filter was evaluated as being capable of removing VOCs well over a long period of time.

[0115] [Lead removal performance measurement] The lead removal performance of the adsorption filter was measured by the following method. First, diluted water with a lead concentration of 150±15 ppb was prepared, and the pH of the diluted water was adjusted to 8.30 to 8.60 using an aqueous sodium hydroxide solution, and the temperature was adjusted to 20±3°C to prepare test water. This test water was passed from the outside to the inside of the cylindrical adsorption filter at a flow rate of 1.9 L / min, and the test water and treated water were simultaneously collected over time to prepare samples. The lead concentration in these samples was measured by an ICP emission spectrometer ("ICPE9820", Shimadzu Corporation) using an ultrasonic nebulizer ("UAG-1", Shimadzu Corporation). Furthermore, the cumulative amount of water passing per volume of the adsorption filter at the time when the lead concentration of the treated water became 10 ppb or more was calculated as the lead removal rate life (L / cc). In this test, a lead removal rate life (L / cc) of 10.5 L / cc or more was used as the pass criterion, and the adsorption filter was evaluated as being capable of removing lead well over a long period of time.

[0116] Next, the method for producing the adsorption filters in each of the Examples and Comparative Examples, as well as the results of measuring the physical properties and evaluating the performance of the produced adsorption filters, will be described in detail.

[0117] <Example 1> The powdered activated carbon A, the titanosilicate-based lead adsorbent, the acrylic fibrous binder, and the cellulose fibrous binder were mixed in the ratio shown in Table 1 below to make a total of 8.36 kg, and tap water was added. The amount of the slurry after the addition was 83.6 L.

[0118] Next, the core was attached to the cylindrical molding frame (outer diameter 40.0 mmφ, center shaft diameter 11.6 mmφ, and outer diameter flange interval 365.0 mmH) shown in Figure 1 described above, and the obtained slurry was molded to 43 mmφ, which is slightly larger than the outer diameter of the mold, by only suction at 400 mmHg, and then dried. Next, the obtained molded body was attached to the automatic grinding machine shown in Figure 4, and the outer surface of the molded body was ground at a molded body rotation speed of 360 rpm, a grindstone rotation speed of 2535 rpm, and a grindstone moving speed of 250 mm / 10 sec (2.5 cm / sec), to obtain a cylindrical adsorption filter with an outer diameter of 38.6 mmφ, an inner diameter of 12 mmφ, and a height of 108.0 mmH.

[0119] The adsorption filter thus obtained was subjected to measurement of its density and pore volume using a mercury porosimeter by the methods described above. The results of the measurements of the physical properties of the adsorption filter are summarized in Table 3 below.

[0120] After that, a nonwoven fabric was wrapped around the circumference of the obtained adsorption filter in one layer. Next, a cylindrical packing made of ABS resin with a thickness of about 1 mm and an outer diameter of 39 mm was adhered to one end of the adsorption filter with a hot melt adhesive. Furthermore, a packing with an outer diameter of 39 mm, two holes of 2.2 mm in the center, and a screw part connectable to a water flow test housing was adhered to the other end of the adsorption filter with a hot melt adhesive.

[0121] The adsorption filter, which is made by wrapping nonwoven fabric and attaching packing, has an average diameter of 50 mm, a length of approximately 117 mm, and an internal volume of approximately 230 cm 3The filter was loaded into an ABS resin housing. Water was passed from the outside to the inside of the filter, and the turbidity filtration capacity, turbidity filtration capacity when backwashing was performed, ultrafine particle removal performance, initial water flow resistance, VOC removal performance, and lead removal performance were evaluated using the method described above. The results of these performance evaluations are also summarized in Table 3 below. Table 3 also lists the particle content (volume %) of the raw activated carbon with a particle diameter of 10 μm or less, measured using the method described above.

[0122] <Examples 2 to 6> As shown in Table 1 below, in Examples 2 to 6, cylindrical adsorptive filters were obtained in the same manner as in Example 1, except that powdered activated carbon B to powdered activated carbon F were used as the raw activated carbon instead of powdered activated carbon A. The results of physical property measurements and performance evaluations of the adsorption filters in Examples 2 to 6 are summarized in Table 3 below.

[0123] <Comparative Examples 1 to 5> As shown in Table 2 below, in Comparative Examples 1 to 5, cylindrical adsorptive filters were obtained in the same manner as in Example 1, except that powdered activated carbon G to powdered activated carbon K were used as the raw activated carbon instead of powdered activated carbon A. The physical property measurement results and performance evaluation results of the adsorption filters in Comparative Examples 1 to 5 are summarized in Table 4 below.

[0124] [Table 1]

[0125] [Table 2]

[0126] In Tables 1 and 2, "-" means that it is not included. The amounts of the acrylic fibrous binder and the cellulose fibrous binder in Tables 1 and 2 are shown in parts by mass relative to 100 parts by mass of the total of the raw material activated carbon and the titanosilicate lead adsorbent.

[0127] [Table 3]

[0128] [Table 4]

[0129] Further, FIG. 5 shows a graph of the results of the water flow test using test water containing turbid substances in Examples 1 to 3 and Comparative Example 1. In addition, FIG. 6 shows a graph of the results of the water flow test using test water containing turbid substances in Examples 1 to 3 and Comparative Example 1 when backwashing is performed. Also, FIG. 7 shows a graph of the results of the water flow test using test water containing turbid substances in Examples 4 to 6. FIG. 8 shows a graph of the results of the water flow test using test water containing turbid substances in Examples 4 to 6 when backwashing is performed. FIG. 9 shows a graph of the results of the water flow test using test water containing turbid substances in Comparative Examples 2 to 5. FIG. 10 shows a graph of the results of the water flow test using test water containing turbid substances in Comparative Examples 2 to 5 when backwashing is performed.

[0130] [Consideration] As shown in Table 3 above, the adsorption filters of Examples 1 to 6 have a pore volume of 0.06 cm3 with a pore diameter of 15 μm or more and 30 μm or less. 3 / cc~0.30cm 3 / cc. Furthermore, the activated carbons (powdered activated carbons A to F) used as raw materials for the adsorption filters of Examples 1 to 6 satisfy all of the conditions that D50 is 30 μm or more and 110 μm or less, D90 is 110 μm or more, and the particle content of particles with a particle diameter of 10 μm or less is 1.2 vol% or more and 8.9 vol% or less. On the other hand, the adsorption filters of Comparative Examples 1 to 5 have a pore volume of 0.06 cm for pores with a diameter of 15 μm or more and 30 μm or less. 3 / cc~0.30cm 3 / cc range, or the raw activated carbon does not satisfy the conditions that D50 is 30 μm or more and 110 μm or less, D90 is 110 μm or more, and the particle content of particle diameters of 10 μm or less is 1.2 vol.% or more and 8.9 vol.% or less.

[0131] As shown in Tables 3 and 4 and Figures 5 and 7, the adsorption filters of Examples 1 to 6 were able to remove not only ultrafine particles but also turbid substances well for a long period of time and maintained excellent water permeability, compared to the adsorption filter of Comparative Example 1. Furthermore, as shown in Tables 3 and 4, the adsorption filters of Examples 1 to 6 also had lower initial water resistance values ​​compared to the adsorption filter of Comparative Example 1. This is thought to be because the adsorption filter of Comparative Example 1, which uses a small particle size of raw activated carbon, can remove ultrafine particles to the same extent as the filters of Examples 1 to 6, but becomes clogged with larger turbid substances, which reduces water permeability and ultimately shortens the life of the adsorption filter.

[0132] Furthermore, as shown in Table 3 and Figures 6 and 8, the adsorption filters of Examples 1 to 6 had a high flow rate regeneration effect by backwashing, and were able to maintain good turbidity removal performance for a long period of time. On the other hand, in the adsorption filter of Comparative Example 1, the particle size of the raw activated carbon was small, and turbidity substances were not easily released even when backwashing was performed, so it is believed that the life of the adsorption filter could not be extended significantly in the end.

[0133] The adsorption filter of Comparative Example 2 had good water permeability compared to the adsorption filters of Examples 1 to 6, but was inferior in both turbidity removal performance (including the case where backwashing was performed) and ultrafine particle removal performance, and the filter life was shortened. This is thought to be because the pore diameters of the adsorption filter were distributed over a larger range compared to Examples 1 to 6.

[0134] The adsorption filter of Comparative Example 3 also had good water permeability compared to the adsorption filters of Examples 1 to 6, but was inferior in both turbidity removal performance (including the case with backwashing) and ultrafine particle removal performance, and the filter life was shortened. This is thought to be because the particle size of the raw activated carbon was significantly larger than those of Examples 1 to 6.

[0135] The adsorption filter of Comparative Example 4 was inferior in turbidity removal performance (including the case where backwashing was performed) and had a shorter filter life than the adsorption filters of Examples 1 to 6. This is believed to be because the content of particles with a particle diameter of 10 μm or less in the raw activated carbon was too low compared to Examples 1 to 6.

[0136] The adsorption filter of Comparative Example 5 was clogged with turbid substances, had poor water permeability, and had a short filter life compared to the adsorption filters of Examples 1 to 6. This is thought to be because, like Comparative Example 1, the particle size of the raw activated carbon was smaller than those of Examples 1 to 6.

[0137] Furthermore, as shown in Table 3 above, the adsorption filters of Examples 1 to 6 were able to effectively remove VOCs and lead, which corresponds to a harmful substance, over a long period of time.

[0138] This application is based on Japanese Patent Application No. 2022-053499 filed on March 29, 2022, the contents of which are incorporated herein by reference.

[0139] In order to express the present invention, the present invention has been described adequately and sufficiently through the embodiments and examples with reference to specific examples, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments and examples. Therefore, unless the changes or improvements made by those skilled in the art are at a level that departs from the scope of the claims described in the claims, the changes or improvements are interpreted as being included in the scope of the claims. [Industrial Applicability]

[0140] The adsorption filter of the present invention is preferably used as a water purification cartridge by being filled into a housing in order to remove harmful substances, such as free residual chlorine, VOCs (volatile organic compounds) such as trihalomethanes, pesticides, and mold odors contained in tap water.

Claims

1. An adsorption filter comprising a molded body containing activated carbon and a binder, The pore volume of the adsorption filter having a pore diameter of 15 μm or more and 30 μm or less, measured by mercury intrusion porosimetry, is 0.06 cm ３ / cc ~ 0.30cm ３ / cc.

2. An adsorption filter comprising a molded body containing activated carbon and a binder, In the volume-based cumulative particle size distribution of the activated carbon, D50 is 30 μm or more and 110 μm or less, and D90 is 110 μm or more, An adsorption filter, wherein the activated carbon has a particle content of particles having a particle diameter of 10 μm or less of 1.2 vol % or more and 8.9 vol % or less.

3. The volume of pores having a diameter of 7 μm or less on a volume basis of the adsorption filter measured by mercury intrusion porosimetry is 0.10 cm ３ 3. The adsorption filter according to claim 1, wherein the adsorption capacity is 100% or more.

4. In the volume-based cumulative particle size distribution of the activated carbon, D50 is 30 μm or more and 110 μm or less, and D90 is 110 μm or more, 2. The adsorption filter according to claim 1, wherein the content of particles having a particle diameter of 10 μm or less in the activated carbon is 1.2 vol % or more and 8.9 vol % or less.

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