JP6912244B2 - Filter cartridge and filter - Google Patents

Description

The present invention relates to a filter cartridge and a filter in which a non-woven fabric is laminated or wound.

In recent years, with the progress of semiconductor manufacturing technology in the electronic industry, the design dimension of the wiring pitch of integrated circuits has been reduced to a dozen nm. Due to the miniaturization of integrated circuits, the operating speed tends to increase and the power consumption tends to decrease. In the manufacturing process of integrated circuits, metal impurities contained in the chemical solution cause a short circuit of wiring and a decrease in the current value, which causes a decrease in the yield. Therefore, it is necessary to purify the chemical solution. Distillation and ion exchange resins are used as means for removing such metal impurities. However, distillation has a high cost, and ion exchange resins have problems such as slow processing speed and contamination by eluates. is doing. Conventionally, a depth type cartridge filter for adsorbing and removing a metal in a solution has been known. Patent Document 1 proposes to wrap a meltblown non-woven fabric around a hollow pipe having holes for use. In Patent Document 2, some of the applicants have proposed a cartridge filter in which a non-woven fabric composed of fibers obtained by graft-polymerizing an ion exchange group and a non-woven fabric composed of fibers obtained by non-graft polymerization are laminated. There is.

Special Table No. 11-504853 JP-A-2009-090259

However, the conventional filter does not have high metal adsorption / removal efficiency, and improvement of this is required.

The present invention provides a filter cartridge and a filter having high metal adsorption and removal efficiency in order to solve the above-mentioned conventional problems.

The filter cartridge of the present invention is a filter cartridge in which a plurality of types of filtration base cloths are laminated or wound around a hollow inner cylinder to adsorb and remove metals in a solution, and the filtration base cloth is made of a metal on a polyolefin fiber. It is a non-woven fabric in which adsorbing groups are chemically bonded, and the filtering base cloth includes a non-woven fabric layer A located on the downstream side and a non-woven fabric layer B located on the upstream side, and the non-woven fabric layer A has a sulfonic acid group as a metal adsorbing group. the consists of chemically bonded polyolefin fibers, the nonwoven fabric layer B, N- methyl -D- glucamine group metal adsorbing group, at least one selected iminodiacetic acid group (iminodiacetic acid groups) and iminodiethanol group or al The polyolefin fibers composed of chemically bonded polyolefin fibers and constituting the nonwoven fabric layers A and B are characterized by being composed of high-density polyethylene fibers having a single fiber average diameter of 0.2 to 10 μm.

The filter of the present invention is a filter for adsorbing and removing metal in a solution, which has a filtering portion in which a plurality of types of filtering base cloths are laminated or wound around a hollow inner cylinder, and the filtering base cloth is a polyolefin fiber. It is a non-woven fabric in which a metal adsorbing group is chemically bonded to, and the filtering base cloth includes a non-woven fabric layer A located on the downstream side and a non-woven fabric layer B located on the upstream side, and the non-woven fabric layer A is sulfone as a metal adsorbing group. at least consists of polyolefin fibers chemically bonded acid groups, the non-woven fabric layer B is a metal adsorbing group N- methyl -D- glucamine group is selected iminodiacetic acid group (iminodiacetic acid groups) and iminodiethanol group or al The polyolefin fibers constituting the non-woven fabric layers A and B, which are composed of a type of chemically bonded polyolefin fibers, are characterized by being composed of high-density polyethylene fibers having a single fiber average diameter of 0.2 to 10 μm.

According to the present invention, a laminated or wrapping type filter cartridge includes a non-woven fabric layer A located on the downstream side and a non-woven fabric layer B located on the upstream side, and the non-woven fabric layer A contains a sulfone group as a metal adsorption group. The non-woven layer B is composed of chemically bonded polyolefin fibers, and the non-woven layer B has an amino group, an N-methyl-D-glucamine group, an iminodiacetic acid group (iminodiacetic acid group), an iminodiethanol group, an amidoxim group, and a phosphoric acid as metal adsorption groups. By being composed of a polyolefin fiber in which at least one selected from a group, a carboxylic acid group and an ethylenediamine triacetate group is chemically bonded, a base cloth for filtration having high metal adsorption / removal efficiency can be obtained.

FIG. 1 is a schematic partial cut-out view of a filter cartridge according to an embodiment of the present invention. FIG. 2 is a schematic explanatory view of the processing apparatus incorporating the depth type cartridge filter. FIG. 3 is a schematic explanatory view of a liquid flow test apparatus according to an embodiment of the present invention. FIG. 4 is a graph showing the removal performance of the filters of Example 1 and Comparative Example 1 with respect to K. FIG. 5 is a graph showing the removal performance of the filters of Comparative Examples 2 and 3 with respect to K. FIG. 6 is a graph showing the removal performance of the filters of Example 2 and Comparative Example 4 with respect to Cu. FIG. 7 is a graph showing the removal performance of the filters of Comparative Examples 5 and 6 with respect to Cu. FIG. 8 is a graph showing the removal performance of the filters of Example 3 and Comparative Example 7 with respect to Na. FIG. 9 is a graph showing the removal performance of the filters of Comparative Examples 8 and 9 with respect to Na.

The present invention is a filter cartridge in which a plurality of types of filtration base cloths are laminated or wound around a hollow inner cylinder. The filtration base cloth is a non-woven fabric in which a metal adsorbing group is chemically bonded to a polyolefin fiber, and the filtration is performed. The base cloth includes a non-woven fabric layer A located on the downstream side and a non-woven fabric layer B located on the upstream side. If wrapped in this order, it is optional to further wrap other types of non-woven fabrics. The non-woven layer A is composed of a polyolefin fiber to which a sulfone group is chemically bonded as a metal adsorbing group, and the non-woven layer B has an amino group, an N-methyl-D-glucamine group and an iminodiacetic group as metal adsorbing groups. It is composed of a polyolefin fiber in which at least one selected from (iminodiacetic acid group), iminodiethanol group, amidoxime group, phosphoric acid group, carboxylic acid group and ethylenediamine triacetate group is chemically bonded. As a result, the metal can be removed efficiently. It should be noted that a plurality of types of filtration base cloths are also included in which different types of filtration base cloths are combined to form one filtration base cloth.

In the present invention, the non-woven fabric layer B is particularly preferably composed of a polyolefin fiber to which an iminodiethanol group is chemically bonded. This is because the metal removal efficiency is high. For metals that can be adsorbed, the sulfonic acid group mainly adsorbs Na, Cu and K, and the iminodiethanol group mainly adsorbs Cr, Al and Fe.

The polyolefin fibers constituting the non-woven fabrics A and B are preferably long fibers. This is because the long-fiber non-woven fabric is less likely to generate fiber waste and has high filter performance. Among them, a melt-blown long fiber non-woven fabric having a high mass (weight) per area of 10 to 100 g / m ^{2 is preferable.}

The average diameter of the single fibers of the polyolefin fibers constituting the nonwoven fabrics A and B is preferably 0.2 to 10 μm. Within the above range, the filter performance is high. In addition, the surface area (specific surface area) can be increased, and the surface of the base material in the graft polymerization reaction can be increased, so that the graft ratio can be increased.

The polyolefin fiber is preferably one selected from polypropylene, a copolymer of propylene and ethylene, polyethylene, or a copolymer of ethylene and another α-olefin having 4 or more carbon atoms, and high-density polyethylene is particularly preferable. These polymers are inert, stable to chemicals and capable of graft polymerization.

The filter cartridge is a filter cartridge including a hollow inner cylinder and a filter base cloth, the filter base cloth is a non-woven fabric in which a metal adsorbent is chemically bonded to a polyolefin fiber, and the filter base cloth is a non-woven fabric. A filter cartridge having a laminated structure formed by being wound around the hollow inner cylinder is preferable.

The filter of the present invention is a filter incorporating the filter cartridge. The filter cartridge has a filter base cloth wrapped around the inner cylinder and is stored in a container. When incorporating the filter cartridge into the filter container, incorporate the filter cartridge into the filter with the filter cartridge stored in the container. In the case of a cartridge type filter, the filter function can be regenerated by exchanging only the filter cartridge. However, in the case of exchanging the entire filter container, for example, a capsule type filter, the present invention also applies. It includes. In the case of a capsule type filter, the portion corresponding to the filter cartridge is a filtration portion.

Next, a method of chemically bonding various functional groups to the polyolefin fiber will be described. The polyolefin fiber is irradiated with radiation such as electron beam or γ-ray and then brought into contact with an emulsion solution containing a reactive monomer such as GMA, or the polyolefin fiber is brought into contact with an emulsion solution containing a reactive monomer and then subjected to an electron beam. , Γ-rays and other radiation is applied to graft-polymerize the reactive monomer onto the polyolefin fiber. When irradiating an electron beam, an irradiation amount of usually 1 to 200 kGy, preferably 5 to 100 kGy, and more preferably 10 to 50 kGy may be achieved. As for the atmospheric conditions, it is preferable to perform irradiation in a nitrogen atmosphere. Commercially available electron beam irradiation devices can be used. For example, EC250 / 15 / 180L (manufactured by Iwasaki Electric Co., Ltd.) and EC300 / 165/800 (Iwasaki Electric Co., Ltd.) are available as area beam type electron beam irradiation devices. ), EPS300 (manufactured by NHV Corporation), etc. can be used.

Specific examples of the graft polymerization method include a liquid phase graft polymerization method, in which a non-woven fabric is activated by irradiation with γ-rays, electron beams, or the like, and then water, a surfactant, and a reactive monomer are used. The graft polymerization is completed on the non-woven substrate by immersing it in an emulsion containing Introduce functional functional groups such as iminodiacetic acid group (iminodiacetic acid group), iminodiethanol group, amidoxime group, phosphoric acid group, carboxylic acid group, ethylenediamine triacetate group, that is, ion exchange group and / or chelate group. The present invention is not particularly limited to the liquid phase graft polymerization method, which is a vapor phase graft polymerization method in which the substrate is brought into contact with the vapor of the monomer for polymerization, the substrate is immersed in the monomer solution, and then taken out from the monomer solution. An impregnated vapor phase graft polymerization method in which the reaction is carried out in the gas phase can also be used. Typical chemical formulas of functional functional groups are (Chemical formula 1) as a sulfonic acid group (SC group), (Chemical formula 2) as an iminodiethanol group (IDE group), and (Chemical formula 3) as an iminodiacetic acid group (IDA group), (Chemical formula 3). The N-methyl-D-glucamine group (NMDG group) is shown in Chemical formula 4).

However, R in (Chemical formula 1) to (Chemical formula 4) is polyethylene (PE) + GMA (Chemical formula 5) or polypropylene (PP) + GMA (Chemical formula 6).

However, n and m in the above (Chemical 5) to (Chemical formula 6) are integers of 1 or more.

Table 1 summarizes the characteristics of the functional functional groups of the above-mentioned (Chemical formula 1) to (Chemical formula 4) of the present invention.

This will be described below with reference to the drawings. In the drawings below, the same reference numerals indicate the same thing. FIG. 1 is a schematic partial cut-out view of a filter cartridge in a depth type cartridge filter according to an embodiment of the present invention. The filter cartridge 1 is used by wrapping at least two layers of a filtration base cloth around a hollow inner cylinder (hollow pipe having a hole) 2. The non-woven fabric layer (A) 3 located on the downstream side and the non-woven fabric layer (B) 4 located on the upstream side are laminated.

FIG. 2 is a schematic explanatory view of the depth type cartridge filter. The depth type cartridge filter 5 has end caps 9a and 9b attached to the depth type filter cartridge 10, is incorporated in the filter container 6, water to be treated is supplied from the supply port 7, and the filter cartridge 10 is from the outside to the inside. The water to be treated passes toward the water, and the metal is removed during this period, and the water is taken out from the treated water outlet 8.

FIG. 3 is a schematic explanatory view of a liquid flow test apparatus according to an embodiment of the present invention. The liquid flow test device 11 supplies the water to be treated 13 contained in the container 12 from the fluororesin (PFA) tube 14 and the tube pump 15 to the laminated filter 17 via the column 16, adsorbs and removes the metal, and treats the water. Put 19 in the container 18. The laminated filter 17 is composed of a non-woven fabric layer (A) 17a located on the downstream side and a non-woven fabric layer (B) 17b located on the upstream side. The liquid passage test apparatus shown in FIG. 3 is a column type laminated type filter, but has the same basic structure as the wrapping type filter. Therefore, the test result of the wrapping type filter can be regarded as the same as that of the column type laminated type.

Hereinafter, the present invention will be specifically described with reference to Examples. The present invention is not limited to the following examples.

<Graft rate>
The graft ratio was calculated by the following formula from the mass of the non-woven fabric before and after the graft.
Graft rate (%) = 100 x (BA) / A
(In the formula, A represents the mass of the non-woven fabric base material before grafting, and B represents the mass of the non-woven fabric base material after grafting.)
<Elemental analysis>
The metal concentration in the sample sampled was measured using atomic absorption spectroscopy in which trace elements can be quantified. From the obtained metal concentration, the metal removal rate (%) was calculated by the following formula (Equation 1). The Blank solution in the formula indicates the metal concentration in the prepared metal solution.

(Number 1)
Metal removal rate (%) = [(Blank liquid metal concentration-Blank liquid metal concentration after passing through the filter) / Blank liquid metal concentration] x 100

<Method of introducing sulfonic acid group>
(Electron beam irradiation process and graft chain introduction process)
One side of a melt-blown non-woven fabric (mesh mass 81 g / m ² , thickness 0.38 mm, fiber filling rate 24%) made of high-density polyethylene with an average fiber diameter of 6 μm is irradiated with an electron beam under a nitrogen atmosphere at an acceleration voltage of 200 kV. Irradiation was performed at a dose of 50 kGy. Next, the irradiated melt-blown non-woven fabric was immersed in a monomer solution in an emulsion state prepared in advance and replaced with nitrogen (nitrogen bubbling), and emulsion graft polymerization was carried out for 4 hours while maintaining the temperature at 55 ° C.
The monomer solution used is a pure water emulsion solution containing 1.6% by mass of glycidyl methacrylate (GMA) and 0.2% by mass of the surfactant Tween 20 (manufactured by Nacalai Tesque, Inc.) based on the total weight of the solution.
When the graft rate was evaluated, the GMA graft rate was 50%.
(Sulfonic acid group introduction process)
The GMA graft-polymerized non-woven fabric obtained above was immersed in a sodium sulfite solution prepared by dissolving sodium sulfite in isopropanol: 15% by mass / pure water: 85% by mass and having a concentration of 10% by mass, and heated at 80 ° C. for 9 hours. The sulfonic acid group was introduced. The non-woven fabric was taken out, washed with pure water, and dried to obtain a sulfonic acid-type non-woven fabric.
The sulfonic acid-type non-woven fabric obtained above was immersed in sulfuric acid having a concentration of 1N and heated at 80 ° C. for 2 hours to open the ring of the residual epoxy group and replace the sodium ion with a hydrogen ion. The non-woven fabric was taken out, washed with pure water, and dried to obtain a sulfonic acid-type ion-exchanged non-woven fabric having an ion exchange capacity of 2 meq / g. The thickness of the non-woven fabric was 0.82 mm.

<Iminodiethanol group introduction process>
(Electron beam irradiation process and graft chain introduction process)
The electron beam irradiation step and the graft chain introduction step were carried out by the same method as the sulfonic acid group. When the graft rate was evaluated, the GMA graft rate was 50%.
(Iminodiethanol group introduction process)
The GMA graft-polymerized non-woven fabric obtained above was immersed in an iminodiethanol solution having a concentration of 20% by mass prepared by dissolving iminodiethanol in pure water, and heated at 80 ° C. for 4 hours to introduce iminodiethanol groups. .. The non-woven fabric was taken out, washed with pure water, and dried to obtain an iminodiethanol-type non-woven fabric having an ion exchange capacity of 2.0 meq / g. The thickness of the non-woven fabric was 0.75 mm.

<Iminodiacetic acid group introduction process>
(Electron beam irradiation process and graft chain introduction process)
The electron beam irradiation step and the graft chain introduction step were carried out by the same method as the sulfonic acid group. When the graft rate was evaluated, the GMA graft rate was 50%.
(Iminodiacetic acid group introduction process)
The GMA graft-polymerized non-woven fabric obtained above was prepared by dissolving iminodiacetic acid disodium hydrate in levelan LV-8: 17% by mass / pure water: 71% by mass to produce iminodiacetic acid disodium hydration at a concentration of 12% by mass. The GMA graft-polymerized non-woven fabric obtained above was immersed in a product solution and heated at 80 ° C. for 9 hours to introduce iminodiacetic acid groups.
The iminodiacetic acid-type non-woven fabric obtained above was immersed in hydrochloric acid having a concentration of 6N to replace sodium ions with hydrogen ions. The non-woven fabric was taken out, washed with pure water, and dried to obtain an iminodic acid-type ion-exchanged non-woven fabric having an ion exchange capacity of 0.8 meq / g. The thickness of the non-woven fabric was 0.68 mm.
<Making a metal removal filter>
The laminated filter 17 shown in FIG. 3 was used. That is, it is composed of the non-woven fabric layer (A) 17a located on the downstream side and the non-woven fabric layer (B) 17b located on the upstream side. The two types of non-woven fabric base materials are cut to a diameter of 7 mmΦ, and a total of 10 sheets of 5 sheets each are laminated in a 7 mmΦ PFA (copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) columns in a different order. Two kinds of functional group composite type filters 17 were prepared.
_{A sulfonic acid base material (hereinafter referred to as SC K} ) was used as the non-woven fabric layer A, and an iminodiethanol base material (hereinafter referred to as IDE _{Cr) was used as the non-woven fabric layer B.} SC _K adsorbs potassium (K), and IDE _Cr adsorbs chromic acid (hereinafter referred to as chromium (Cr)). The base material weight (g / sheet) is as follows.
SC base material = 0.0059 (g / sheet)
IDE base material = 0.0053 (g / sheet)
IDA base material = 0.0055 (g / sheet)

(Example 1, Comparative Example 1)
<Preparation of metal solution>
A potassium dichromate standard solution (1000 ppm), which is a special reagent manufactured by Nacalai Tesque, was diluted with ultrapure water to prepare a 1000 ppb metal solution (Cr = 1000 ppb, K = 2000 ppb).
<Liquid flow / sampling>
As shown in FIG. 3, a metal solution (potassium dichromate) was passed through a filter at 3.1 mL / min using a tube pump, and the solution after passing through the substrate was sampled in a 100 mL PFA bottle.
In this example and comparative example, the metal removal performance with respect to K was examined.
FIG. 4 shows the metal removal rates of the functional group composite type filters of (SC _K → IDE _Cr ) and (IDE _Cr → SC _K). From this result, when K is removed in a solution system in which K and Cr are mixed, Cr is removed in advance with an IDE group, and then K is removed with SC, rather than K being removed with an SC single group (IDE). _Cr → SC _K) it is, was found to exhibit a high removal rate.

(Comparative Examples 2-3)
The experiment was carried out in the same manner as in Example 1 except that the sulfonic acid _{base material (SC K} ) was used as the non-woven fabric layer and the iminodiethanol base material (IDE _{Cr) was used as the non-woven fabric layer.} This metal removal rate is shown in FIG. SC _K has been able to remove K, but IDE _Cr has not. These single filter value of the combined functional group composite filter plus the metal removal rate (hereinafter, described as the theoretical value), showed comparable values and SC _K.

(Example 2, Comparative Example 4)
In this example and comparative example, the metal removal performance with respect to Cu was examined. The filter structure was the same as in Example 1.
<Preparation of metal solution>
Sodium (Na) standard solution (1000 ppm) and copper (Cu) standard solution (1000 ppm), which are special reagents manufactured by Nacalai Tesque, are diluted with ultrapure water to form a 1000 ppb metal solution (Na = 1000 ppb, Cu = 1000 ppb). Was prepared.
<Liquid flow / sampling>
A metal solution (Na, Cu) was passed through the metal solution (Na, Cu) at the same flow rate as in Example 1 and sampled.
<Result of metal removal rate>
FIG. 6 shows the metal removal rates of the functional group composite type filters of (SC _{Na, Cu} → IDA _Cu ) and (IDA _Cu → SC _{Na, Cu).} From this result, it was found that when removing Cu in a solution system in which Na and Cu are mixed, the removal rate is higher when the combination of IDA and SC is used than when the Cu is removed by the IDA and SC single groups. .. Regarding the order of IDA and SC, it was found that the order of _{IDA Cu} → SC _{Na, Cu showed a higher removal rate.}

(Comparative Examples 5 to 6)
The metal removal rates of the two types of single filters (SC _{Na, Cu} ) and (IDA _{Cu) are shown in FIG. Cu} can be removed with IDA Cu and SC _{Na, Cu.} Further, the value of the functional group composite type filter (hereinafter referred to as the theoretical value) obtained by adding the metal removal rates of these single filters is SC _{Na, Cu} + IDA _Cu .

(Example 3, Comparative Example 7)
In this example, the metal removal performance for Na was examined.
FIG. 8 shows the metal removal rates of the functional group composite type filters of (SC _{Na, Cu} → IDA _Cu ) and (IDA _Cu → SC _{Na, Cu).} From this result, when Na is removed in a solution system in which Na and Cu are mixed, Cu is removed in advance by the IDA group and then Na is removed by SC (IDA), rather than removing Na by the SC single group. _{It was found that Cu} → SC _{Na, Cu} ) showed a higher removal rate than the theoretical value.

(Comparative Example 8, Comparative Example 9)
FIG. 9 shows the metal removal rates of the two types of single filters (SC _{Na, Cu} ) and (IDA _Cu). SC _{Na and Cu} were able to remove _{Na, but IDA Cu} could not. The metal removal rate of SC _{Na and Cu} shows a negative value from the middle because Na is released by the functional group adsorbing Na adsorbing Cu with stronger adsorption power. be. In addition, the values of the functional group composite type filter (hereinafter referred to as theoretical values) obtained by adding the metal removal rates of these single filters showed the same values as _{SC Na and Cu.}

Considering the above examples and comparative examples, as a result of investigating the influence of the stacking order of the base materials in the functional group composite filter, the metals that are not the adsorption target of the functional groups are reduced, and then the metal that is the adsorption target is adsorbed. It was found that the metal removal performance was improved by using such a stacking order. One speculation is that the smaller the number of metals that are not the target of adsorption with respect to the metal that is the target of adsorption of the functional group, the higher the probability of contact between the functional group and the target metal.

The filter cartridge of the present invention is useful for a depth type cartridge filter in which a non-woven fabric is wound in a cylindrical shape.

1,10 Depth type filter cartridge 2 Hollow inner cylinder (hollow pipe with holes)
3,17a Non-woven fabric layer (A) located on the downstream side
4,17b Non-woven fabric layer (B) located on the upstream side
5 Depth type cartridge filter 6 Filter container 7 Supply port 8 Treated water outlet 9a, 9b End cap 11 Liquid flow test device 12, 18 Container 13 Water to be treated 14 Fluororesin (PFA) tube 15 Tube pump 16 Column 17 Laminated filter 19 Treated water

Claims (6)

A filter cartridge that adsorbs and removes metals in a solution by laminating or wrapping multiple types of filtration base cloth around a hollow inner cylinder.
The filtration base cloth is a non-woven fabric in which a metal adsorbing group is chemically bonded to a polyolefin fiber.
The filtration base cloth includes a non-woven fabric layer A located on the downstream side and a non-woven fabric layer B located on the upstream side.
The non-woven fabric layer A is composed of a polyolefin fiber in which a sulfonic acid group is chemically bonded as a metal adsorbing group.
The nonwoven fabric layer B is a metal adsorbing group N- methyl -D- glucamine group, consists of iminodiacetic acid groups (iminodiacetic acid groups) and polyolefin fibers chemically coupling at least one selected iminodiethanol group or al,
The polyolefin fibers constituting the non-woven fabric layers A and B are made of high-density polyethylene fibers having a single fiber average diameter of 0.2 to 10 μm.
A filter cartridge characterized by that. The filter cartridge according to claim 1, wherein the non-woven fabric layer B is composed of a polyolefin fiber in which an iminodiethanol group is chemically bonded. The filter cartridge according to claim 1 or 2, wherein the polyolefin fibers constituting the non-woven fabric layers A and B are long fibers. The filter cartridge according to any one of claims 1 to 3, wherein the nonwoven fabric layers A and B are melt-blown long fiber nonwoven fabrics having a mass (weight) per area of 10 to 100 g / m ^2. A filter incorporating the filter cartridge according to any one of claims 1 to 4. A filter that adsorbs and removes metals in a solution and has a filtration part in which a plurality of types of filtration base cloths are laminated or wound around a hollow inner cylinder.
The filtration base cloth is a non-woven fabric in which a metal adsorbing group is chemically bonded to a polyolefin fiber.
The filtration base cloth includes a non-woven fabric layer A located on the downstream side and a non-woven fabric layer B located on the upstream side.
The non-woven fabric layer A is composed of a polyolefin fiber in which a sulfonic acid group is chemically bonded as a metal adsorbing group.
The nonwoven fabric layer B is a metal adsorbing group N- methyl -D- glucamine group, consists of iminodiacetic acid groups (iminodiacetic acid groups) and polyolefin fibers chemically coupling at least one selected iminodiethanol group or al,
The polyolefin fibers constituting the non-woven fabric layers A and B are made of high-density polyethylene fibers having a single fiber average diameter of 0.2 to 10 μm.
A filter that features that.

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