JP2020138136A - Positive ion exchanger - Google Patents

Abstract

To provide an ion exchanger having a long filtration life.SOLUTION: In a cross section that passes the center of gravity of an ion exchanger and has a minimum cross sectional area when the ion exchanger is particulate-like or irregular-shape particulate-like, and in a cross section perpendicular to the longer direction when the ion exchanger is fiber-like or sheet-like, the area of the ion exchange layer occupies 30% or more of the total cross sectional area. The ion exchange layer contains nonfreezing water of 50 (wt.%-absolute dry weight base) or more and 100 (wt.%-absolute dry weight base) or less and water of a lowered melting point of 2 (wt.%-absolute dry weight base) or more and 20 (wt.%-absolute dry weight base) or less.SELECTED DRAWING: None

Description

The present invention relates to a cation exchanger having an ion exchange ability suitable for removing hardness components of tap water, heavy metals and the like.

A cation exchanger has been proposed as a means for removing a hardness component from water.

Patent Document 1 discloses, as an ion exchanger, a fiber formed by hydrolyzing polyacrylonitrile (PAN) fiber while cross-linking it with an aqueous solution of hydrazine / sodium hydroxide.

Further, Patent Document 2 discloses a fiber obtained by dry-spinning polyvinyl alcohol mixed with a partially neutralized salt of a high molecular weight polycarboxylic acid.

Further, Patent Document 3 discloses a method for producing a separation functional fiber in which a fiber having a core-sheath structure is irradiated with ionizing radiation and then the fiber is grafted with glycidyl methacrylate.

Japanese Patent Application Laid-Open No. 1-234428 Japanese Patent Application Laid-Open No. 09-087399 Japanese Patent Application Laid-Open No. 08-199480

An ion exchanger having a longer filtration life is desired.

That is, the present invention relates to the following (1) to (6).
(1) A cation exchanger including an ion exchange layer containing a crosslinked polymer compound having a cation exchange group.
When the ion exchanger is in the form of particles or irregularly shaped particles, in a cross section that passes through the center of gravity of the ion exchanger and has the minimum cross section.
When the ion exchanger is fibrous or sheet-like, in a cross section perpendicular to the longitudinal direction,
The area of the ion exchange layer occupies 30% or more of the total cross section, and
In the Na-type wet state, the ion exchange layer contains 50 (% by weight-absolute dry weight standard) or more of antifreeze water, 100 (% by weight-absolute dry weight standard) or less, and 2 (% by weight-weight%-) water having a lower melting point. A cation exchanger comprising 20 (% by weight-absolute dry weight standard) or more (absolute dry weight standard) or more.
(2) The positive according to (1), wherein the ion exchange layer is in a Na-type wet state, and the temperature at which the relaxation time measured by TD-NMR shows a minimum value is −15 ° C. or higher. Ion exchanger.
(3) The cation exchanger according to (1) or (2), wherein the cation exchange group is a carboxy group.
(4) The cation exchanger according to any one of (1) to (3), wherein the cation exchanger has a fibrous shape.
(5) The cation exchanger includes a core material and an ion exchange layer which is arranged around the core material and contains a polymer compound having an ion exchange group (5). The cation exchanger according to any one of 1) to (4).
(6) The ion exchange according to any one of (1) to (5), wherein the core material contains at least one polymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate and nylon. fiber.

When the area of the ion exchange layer in the cross section occupies 30% or more of the total cross section, the ion exchange capacity becomes large and the filtration life becomes long. Further, when the amount of antifreeze water and melting point lowering water contained in the ion exchange layer in the Na-type wet state is within the above range, the ion exchange capacity based on the wet weight can be increased and the filtration life can be extended. ..

1. 1. Ion Exchanger The ion exchanger of the present invention has an ion exchange layer containing a crosslinked polymer compound having an ion exchange group.

In the present embodiment, the ion exchange layer satisfies the following condition (a).
(A) After immersing the ion-exchange fiber in a 1 mol / L sodium hydroxide aqueous solution, the cross section of the Na-type ion exchanger is shown in a scanning electron microscope / electron probe microscope / Electron Probe Micro. When observed with an Analyzer (SEM / EPMA), the sodium atom concentration is 10% by weight or more. When the ion exchanger is in the form of particles or irregularly shaped particles, the cross section of the ion exchanger shall be a cross section that passes through the center of gravity of the ion exchanger and has the minimum cross-sectional area, and the ion exchanger is in the form of fibrous. Or, in the case of a sheet, the cross section is perpendicular to the longitudinal direction. In the cross section, the area of the ion exchange layer occupies 30% or more of the total cross section. It is preferably 40% or more. When the ion exchange layer occupies 30% or more, an ion exchanger having a large ion exchange capacity can be obtained.
The sodium atom concentration (% by weight) is a weight fraction of the sodium element in each pixel in the cross-sectional image when the sample cross-section is measured by SEM / EPMA. The X-ray intensity of Kα (1.191 nm) detected when the standard sample sodium chloride crystal is irradiated with an electron beam by EPMA corresponds to a sodium atom concentration of 39.34% by weight. The sodium atom concentration is calculated from the X-ray intensity of Kα (1.191 nm) detected from the pixels in the cross-sectional image when the cross section of the sample is measured by SEM / EPMA.

The ion exchange layer contains 50 (% by weight-absolute dry weight standard) or more of antifreeze water in a Na-type wet state, and preferably 60 (% by weight-absolute dry weight standard) or more. By containing 50 (% by weight-absolute dry weight standard) or more of antifreeze water, the ions to be adsorbed are promoted to diffuse into the inside of the ion exchange layer, and the ion exchange groups are effectively used, so that the ions are used. The exchange capacity increases. Further, it contains 100 (% by weight-absolute dry weight standard) or less of antifreeze water, and preferably 80 (% by weight-absolute dry weight standard) or less. By containing 100 (% by weight-absolute dry weight standard) or less of antifreeze water, swelling can be suppressed and the ion exchange capacity based on wet weight can be increased. The antifreeze water is water that exists in the vicinity of the ion exchange group in the wet ion exchange layer and does not freeze up to −55 ° C. under atmospheric pressure.

The ion exchange layer contains 1 (% by weight-absolute dry weight standard) or more of water having a lower melting point in a Na-type wet state. By containing 1 (% by weight-absolute dry weight standard) or more of water having a lower melting point, diffusion of ions to be adsorbed is promoted, and the ion exchange capacity is increased by effectively using the ion exchange group. Further, it contains 20 (% by weight-absolute dry weight standard) or less, preferably 10 (% by weight-absolute dry weight standard) or less of water having a lower melting point. By containing 20 (% by weight-absolute dry weight standard) or less of water having a lower melting point, swelling can be suppressed and the ion exchange capacity based on wet weight can be increased. The melting point-lowering water is water existing inside the wet ion exchange layer that freezes at a temperature lower than 0 ° C. and −55 ° C. or higher under atmospheric pressure.

The water content (% by weight-absolute dry weight standard) of the antifreeze water and the water whose melting point is lowered in the Na-type wet ion exchange layer is -55 using the differential scanning calorimetry (DSC method). From the DSC curve of the temperature rise process from ° C to 5 ° C, the bulk moisture content Wf is obtained using the following equation (1), and the melting point lowering moisture content Wfc is obtained using equation (2), and subtracted from the total moisture content Wt. , The antifreeze moisture content Wnf is obtained. Bulk water is water that mainly exists on the surface of a sample and freezes at 0 ° C.

m ₀ is the sample weight, m is the dry weight of the sample, dq / dt is the heat flux signal of DSC, and ΔH ₀ is the amount of heat of fusion at 0 ° C. under atmospheric pressure.

The dry weight m of the sample was the weight after vacuum drying at 110 ° C. for 2 hours or more after the DSC measurement.

In the differential scanning calorimetry of the Na-type wet ion exchange layer, when the ion exchanger contains a portion other than the ion exchange layer, only the ion exchange layer is taken out and the measurement is performed. The method of extracting only the ion exchange layer from the ion exchanger is not particularly limited, but for example, when the ion exchange layer is present near the surface of the ion exchanger, a method of cutting out a portion near the surface of the ion exchanger using a single edge or the like is used. Can be mentioned.

The Na type wet state will be described. After immersing 100 mg of the dry ion exchange layer in 100 mL of a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour, suction filtration is performed. After that, washing with distilled water and suction filtration are performed to remove water on the surface, which is referred to as a Na-type wet state.
In the Na-type wet state, the ion exchange layer has a relaxation time measured by TD-NMR, which is a temperature showing a minimum value, hereinafter referred to as a minimum temperature, but is -15 ° C. or higher, preferably -13 ° C. or higher. is there. The minimum temperature of the relaxation time is observed when the molecular motility of water changes due to temperature changes and becomes motility corresponding to the device frequency, and the motility of water molecules becomes so high that the minimum is confirmed at a lower temperature. Indicates high. Since water with a lower melting point has a higher mobility than water with a lower melting point, the minimum temperature becomes smaller when a large amount of water with a lower melting point is contained in the water with a lower melting point. On the other hand, even when the amount of water whose melting point is lowered is smaller than that of antifreeze water, it is excessively crosslinked, hindering the diffusion of the ions to be adsorbed into the ion exchange layer, and the ion exchange group is not effectively used. In, the motility of water increases and the minimum temperature decreases because the contact between the polar ion exchange group and water is hindered. When the minimum temperature is -13 ° C. or higher, diffusion of ions to be adsorbed can be promoted, ion exchange groups can be effectively used, swelling can be suppressed, and the ion exchange capacity based on wet weight can be increased.
The shape of the ion exchanger is not particularly limited and may be granular, sheet-like, fibrous, etc., but from the viewpoint of filtration life, it is better that the adsorption target can be quickly diffused to the functional groups inside the ion exchanger during filtration. Since the filtration life is long, a fiber shape having the same surface area and a short diffusion path to the center of the ion exchanger is preferable.

The ion exchanger may be formed only from an ion exchange layer containing a crosslinked polymer compound having an ion exchange group, but preferably contains a core material from the viewpoint of maintaining strength. As the core material, polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polylactic acid and polycarbonate; polyamides such as aromatic polyamide, nylon 6, nylon 66, nylon 11, nylon 12, nylon 610; and acrylic. , Polyacrylonitrile, polyvinyl chloride, PTFE, polyvinylidene fluoride and other halogenated polyolefins can be used. It is preferable that the core fiber contains at least one polymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate and nylon. Polyamide and polyester are particularly preferable as the core fiber. Nylon 6 and nylon 66 are particularly preferable for polyamide, and polyethylene terephthalate (PET) is particularly preferable for polyester.

The ion exchange layer contains a polymer compound having a cation exchange group.

Examples of the cation exchange group include a strongly acidic cation exchange group such as a sulfonic acid group and a weakly acidic cation exchange group such as a carboxy group and a phosphoric acid group.

A crosslinked polymer compound having an ion exchange group is a compound in which a plurality of polymer chains are covalently crosslinked at multiple points. The crosslinked polymer compound has a three-dimensional network structure formed by cross-linking and is insoluble in solvents such as water and organic solvents, but the solvent can be retained in the network structure. It can be said that the crosslinked polymer compound is a gel.

The crosslinked polymer compound is, for example, a compound formed by a crosslinking reaction between a polymer compound having a carboxy group and a compound having two or more functional groups that react with the carboxy group.

The polymer compound having a carboxy group is a compound having a plurality of carboxy groups in the molecule, and specific examples thereof include a polymer obtained by hydrolyzing a homopolymer or a copolymer. Examples of the homopolymer include a homopolymer of acrylic acid or methacrylic acid, and examples of the copolymer include a copolymer containing at least one of acrylic acid and methacrylic acid as a monomer component and maleic anhydride as a monomer component. Examples thereof include copolymers contained, acrylic acid esters, and methacrylic acid esters. More specifically, polyacrylic acid is mentioned as a polymer compound having a carboxy group.

A compound having two or more functional groups that react with a carboxy group has a plurality of functional groups in the molecule that react with a carboxy group such as a hydroxyl group, an amino group, a glycidyl group, an oxazoline group, and a carbodiimide group to form a covalent bond. It is a compound, and a compound having a plurality of highly reactive functional groups such as a glycidyl group, an oxazoline group and a carbodiimide group is particularly preferable. Specific examples of such a compound include a polyglycidyl compound, a polyoxazoline compound and a polycarbodiimide compound.

The polyglycidyl compound is a compound containing two or more glycidyl groups in one molecule, and specific compounds include Denacol EX-313 (glycerol polyglycidyl ether) and EX-421 manufactured by Nagase ChemteX Corporation. (Diglycerol polyglycidyl ether), EX-512 (polyglycerol polyglycidyl ether), EX-612 (sorbitol polyglycidyl ether), EX-810 (ethylene glycol diglycidyl ether), EX-821 (polyethylene glycol diglycidyl ether) , EX-850 (diethylene glycol diglycidyl ether).

The polyoxazoline compound is a compound containing two or more oxazoline groups in one molecule, and specific compounds include Epocross WS-300, WS-500, and WS-700 manufactured by Nippon Shokubai Co., Ltd. ..

The polycarbodiimide compound is a compound containing two or more carbodiimide groups in one molecule, and specific compounds include carbodilite V-02, SV-02, and V-10 manufactured by Nisshinbo Chemical Co., Ltd.

One type of crosslinked polymer compound may have a plurality of types of ion exchange groups. Further, one type of crosslinked polymer compound may have only one of a cation exchange group or an anion exchange group, or may have both. The crosslinked polymer compound may be composed of one kind of monomer or may be composed of two or more kinds of monomers.

From the viewpoint of the ion exchange capacity based on the dry weight, the ion exchange layer preferably contains 50% by weight or more, preferably 60% by weight or more of the polymer composed of the acrylic monomer. By containing 50% by weight or more of the polymer composed of the acrylic monomer, an ion exchange fiber having a large ion exchange capacity based on the dry weight can be obtained. Further, it is preferable that the polymer composed of an acrylic monomer is contained in an amount of 95% by weight or less, preferably 85% by weight or less. By containing 95% by weight or less of the polymer composed of the acrylic monomer, the swelling of the ion exchanger can be suppressed and the ion exchange capacity based on the wet weight can be increased.

2. 2. Method for producing cation exchanger The core material can be produced by a spray method or the like in the case of a granular material. When the core material is fibrous, it can be produced by melt spinning, electric field spinning, or wet spinning. When making multiple core fibers, the sea-island melt spinning method is used, the core fibers are island components, the components that are more easily dissolved in the alkaline aqueous solution than the core fibers are the sea components, and only the sea components are dissolved in the alkaline aqueous solution after spinning. There is a way to make it, but it is not limited to this.

The method for forming the ion exchange layer is as follows.

When a core material is included, it has an ion exchange ability by adding a cation exchange group. Examples of the ion exchange group imparted to the core material include a strongly acidic cation exchange group such as a sulfonic acid group and a weakly acidic cation exchange group such as a carboxy group and a phosphoric acid group. Examples of the monomer having a sulfonic acid group include styrene sulfonic acid, vinyl sulfonic acid, 2-acrylamide-2 methylpropane sulfonic acid, and sodium salts and ammonium salts thereof. Examples of the monomer having a carboxy group include acrylic monomers such as acrylic acid and methacrylic acid. In addition, although the monomer itself does not have an ion exchange group and / or a chelate group, examples of the monomer having a functional group that can be converted into an ion exchange group and / or a chelate group include acrylic acid ester, methacrylic acid ester, and methacrylic acid. Examples thereof include glycidyl, styrene, acrylonitrile, achlorine, and chloromethylstyrene. From the viewpoint of ion exchange capacity, it is particularly preferable to use an acrylic monomer.

As a method for imparting such a functional group to the core material, it is preferable to graft-copolymerize the monomer having the above functional group to the core fiber together with the cross-linking agent by using an initiator, but irradiate with gamma rays or electron beams. Then, the monomer having a cation exchange group may be copolymerized with the cross-linking agent on the core fiber. An ion exchange layer is formed around the core fiber by graft-copolymerizing the monomer having a cation exchange group with the cross-linking agent onto the core fiber. Examples of the initiator include ammonium persulfate (APS), azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO) and the like.

In particular, when a peroxide such as ammonium persulfate (APS) or benzoyl peroxide (BPO) is used as the initiator, iron (II) salt, sulfite, sulfinate, hydroxylamine and the like are simultaneously used as the reducing agent. By using it, the reaction can be further promoted.

In addition, tetramethylethylenediamine (TEMED), ethylenediaminetetraacetic acid (EDTA) and the like may be added as substances that promote radical polymerization.

By copolymerizing the cross-linking agent with a monomer having a cation exchange group, swelling is suppressed and the ion exchange capacity based on the wet weight is increased.

As the cross-linking agent, paraformaldehyde, bifunctional acrylamide, bifunctional acrylate, bifunctional methacrylate and divinylbenzene are preferably used. Examples of the bifunctional acrylamide include N, N'-methylenebisacrylamide. Examples of the bifunctional acrylate include 2-hydroxy-3-acryloyloxypropyl methacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, and the like. Examples of the bifunctional methacrylate include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate.

When the ion exchange group contains a carboxy group, the swelling can be suppressed and the ion exchange capacity based on the wet weight can be increased by applying the ion exchange layer to the core material and then performing the heat treatment. The heating temperature is 170 ° C. or higher, preferably 180 ° C. or higher, and more preferably 190 ° C. or higher. When the temperature is 170 ° C. or higher, the carboxy groups are crosslinked by the decarboxylation reaction, swelling can be suppressed, and the ion exchange capacity based on the wet weight can be increased. On the other hand, the heating temperature is preferably 230 ° C. or lower, more preferably 220 ° C. or lower. When the heating temperature is 230 ° C. or lower, excessive progress of crosslink formation can be suppressed. In addition, the time for heating the ion exchanger in this step is preferably 3 minutes or more, and more preferably 5 minutes or more. When the heating time is 3 minutes or more, the cross-linking reaction proceeds sufficiently, so that the polymer compound having a carboxy group is less likely to elute into water. The heating time is preferably 40 minutes or less, more preferably 30 minutes or less. When the heating time is 40 minutes or less, the cost at the time of processing can be suppressed. When the heat treatment is performed, copolymerization by adding a cross-linking agent is not essential.

In addition to copolymerizing a monomer having an ion exchange group on the core material, as a method for imparting an ion exchange layer to the core material, for example, (1) a polymer compound having a carboxy group and a functional group reacting with the carboxy group A step of bringing the core material into contact with an aqueous solution containing two or more compounds, (2) a step of draining excess aqueous solution adhering to the core material after the above step (1), (3) the above step (2). After that, a polymer compound having a carboxy group and a compound having two or more functional groups that react with the carboxy group are subjected to a cross-linking reaction by heating.
In the step (1), as a method of bringing the core material into contact with an aqueous solution containing a polymer compound having a carboxy group and a compound having two or more functional groups that react with the carboxy group, the core material is immersed in the above aqueous solution. A method of applying the above aqueous solution to the core material using a coater, a roller, a spray, or the like can be used.

In this step, the concentration of the polymer compound having a carboxy group in the solution is preferably 100 g / L or more, more preferably 300 g / L or more. When it is 100 g / L or more, the solution can be sufficiently retained on the core fiber. On the other hand, the concentration of the polymer compound having a carboxy group in the solution is preferably 550 g / L or less, more preferably 500 g / L or less. If the concentration exceeds 550 g / L, dissolution becomes difficult and the viscosity of the solution increases, which makes processing difficult.

Further, in this step, the concentration of the compound having two or more functional groups that react with the carboxy group in the solution is preferably 10 g / L or more, more preferably 50 g / L or more. When the concentration of the compound having two or more functional groups that react with the carboxy group in the solution is 10 g / L or more, the elution of the polymer compound having the carboxy group into water can be suppressed. On the other hand, the concentration of the compound having two or more functional groups that react with the carboxy group in the solution is preferably 200 g / L or less, more preferably 100 g / L or less. When the concentration is 200 g / L or less, the excessive progress of the cross-linking reaction is suppressed, and as a result, the number of carboxy groups is maintained.

When a sufficient amount of crosslinks are formed, the swelling of the ion exchange layer is suppressed, so that a large ion exchange capacity can be obtained even on a wet weight basis, and as a result, a long filtration life is realized. Further, water as a carrier is required to transfer ions to the ion exchange group inside the ion exchange layer, but in the case of cross-linking between carboxy groups, another functional group (for example, an epoxy group) is used. The amount of water can be secured more than the cross-linking. Therefore, a large ion exchange capacity can be obtained, and as a result, a long filtration life is realized.

In the step (2), as a method of draining the excess aqueous solution adhering to the core material, a method of draining the liquid using a rubber roller such as a mangle, a method of blowing air with an air nozzle or the like to drain the liquid, A method of draining liquid through a nozzle or the like can be used.

In the step (3), as a method of cross-linking the polymer compound having a carboxy group and the compound having two or more functional groups reacting with the carboxy group by heating, it is heated in a heating device such as an oven or a pin tenter. Or a method of blowing hot air using a dryer or the like can be used.

In this step, the temperature at which the polymer compound having a carboxy group and the compound having two or more functional groups reacting with the carboxy group are crosslinked by heating is 170 ° C. or higher, preferably 180 ° C. or higher, more preferably 180 ° C. or higher. It is over 190 ° C. When the temperature is 170 ° C. or higher, the polymer compound having a carboxy group and the compound having two or more functional groups that react with the carboxy group can be crosslinked, and the carboxy groups can also be crosslinked by a decarboxylation reaction. it can. On the other hand, the heating temperature is preferably 230 ° C. or lower, more preferably 220 ° C. or lower. When the heating temperature is 230 ° C. or lower, the progress of excessive cross-linking can be suppressed.

Further, as the time for heating the core material in this step, it is preferable to heat for 3 minutes or more, and more preferably for 5 minutes or more. When the heating time is 3 minutes or more, the cross-linking reaction proceeds sufficiently, so that the polymer compound having a carboxy group is less likely to elute into water. The heating time is preferably 40 minutes or less, more preferably 30 minutes or less. When the heating time is 40 minutes or less, the cost at the time of processing can be suppressed.
When the ion exchanger is processed into a form such as a woven fabric, a knitted fabric, or a non-woven fabric, the step of coating the core material with a crosslinked polymer compound having an ion exchange group and / or the ion exchange group is added to the single fiber gap of the core material. The step of adhering the crosslinked polymer compound to be possessed may be performed before or after the step of processing the core fiber into a form such as a woven fabric, a knitted fabric, or a non-woven fabric.

3. 3. Utilization of cation exchanger The cation exchanger can be used, for example, as an ion exchange column including a column and a cation exchanger packed in the column.

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

The ratio of the ion exchange layer, the wet weight-based ion exchange capacity, the antifreeze moisture content, the melting point lowering moisture ratio, the minimum temperature of the relaxation time, and the filtration life were measured as follows.

(Ratio of ion exchange layer)
The ion exchange layer is a scanning electron microscope / electron probe microanalyzer in which a cross section of a sodium type ion exchange fiber is immersed in an aqueous sodium hydroxide solution. , SEM / EPMA) indicates a layer having a sodium atom concentration of 10% by weight or more. When the ion exchanger is in the form of particles or irregularly shaped particles, the cross section of the ion exchanger shall be a cross section that passes through the center of gravity of the ion exchanger and has the minimum cross-sectional area, and the ion exchanger is in the form of fibrous. Or, in the case of a sheet, the cross section is perpendicular to the longitudinal direction.
The sodium atom concentration (% by weight) is a weight fraction of the sodium element in each pixel in the cross-sectional image when the sample cross-section is measured by SEM / EPMA. The X-ray intensity of Kα (1.191 nm) detected when the standard sample sodium chloride crystal is irradiated with an electron beam by EPMA corresponds to a sodium atom concentration of 39.34% by weight. The sodium atom concentration was calculated from the X-ray intensity of Kα (1.191 nm) detected from the pixels in the cross-sectional image when the cross section of the sample was measured by SEM / EPMA. Detailed SEM / EPMA measurement conditions are shown.
Equipment: JEOL Electronic Probe Microanalyzer (Fe-EPMA) JXA-8530F
Acceleration voltage: 10kV
Irradiation current: 15nA
Measurement time: 30 ms
Beam size: 1 μm
Analytical X-ray / spectroscopic crystal: Na Kα (1.191 nm) / TAPH (acidic rubidium phthalate)
The sample was measured by forming a cross section with a microtome and vapor-depositing carbon.
The ratio of the area of the ion exchange layer to the total cross section was defined as the ratio of the ion exchange layer.

(Measuring method of wet weight-based ion exchange capacity)
Prepare 100 mL of a 1 mol / L hydrochloric acid aqueous solution for 1 g of the ion exchanger or the ion exchange layer of the ion exchanger, and immerse the ion exchanger in the Na-type wet state or the ion exchange layer of the ion exchanger. (1 hour). After that, it was washed with pure water, and it was confirmed that the supernatant aqueous solution became neutral. Then, the ion exchanger was immersed in a 0.1 M sodium hydroxide aqueous solution (ion exchanger 1 g / 100 mL-sodium hydroxide aqueous solution), and the mixture was stirred for 1 hour. Then, 5 mL of the supernatant of the solution was collected, and 5 mL of a 0.1 mL aqueous hydrochloric acid solution was added. 10 mL of the solution was neutralized and titrated with a 0.1 mol / L sodium hydroxide aqueous solution using a phenolphthalein solution as an indicator. Then, by dividing the number of moles of sodium hydroxide required for neutralization by the weight of the Na-type wet state ion exchanger or the ion exchange layer of the ion exchanger, the ion exchange capacity based on the wet weight (wet weight standard) meq / wet-g).

The Na type wet state will be described. After immersing the dry ion exchanger or the ion exchange layer of the ion exchanger in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour (100 mL-sodium hydroxide aqueous solution with respect to 100 mg of the ion exchanger). , Perform suction filtration. After that, washing with distilled water and suction filtration are performed, and the state in which the water on the surface is removed with a waste cloth is defined as a Na type wet state.

(Antifreeze moisture content, melting point lowering moisture content)
The water content (% by weight-absolute dry weight standard) of the antifreeze water and the water whose melting point is lowered in the Na-type wet ion exchange layer is determined by using the differential scanning calorimetry (DSC method) as follows. Obtained under measurement conditions.
Equipment: DSC Q100 manufactured by TA Instruments
Measurement temperature range: Approximately -55-5 ° C
Heating rate: 0.3 ° C / min
Sample container: Aluminum sealed sample container Temperature / calorie calibration: Pure water (melting point 0.0 ° C, heat of fusion 79.7 cal / g)
Sample weight: 10 mg
From the DSC curve of the temperature rise process from −55 ° C. to 5 ° C., the bulk moisture content Wf is obtained using the above equation (1), and the melting point lowering moisture content Wfc is obtained using the equation (2), and is subtracted from the total moisture content Wt. Therefore, the antifreeze moisture content Wnf was determined. Bulk water is water that mainly exists on the surface of a sample and freezes at 0 ° C.
m0 is the sample weight, m is the dry weight of the sample, dq / dt is the heat flux signal of DSC, and ΔH ₀ is the amount of heat of fusion at 0 ° C. under atmospheric pressure.

The dry weight m of the sample was the weight after vacuum drying at 110 ° C. for 2 hours or more after the DSC measurement.

When the ion exchanger contained a portion other than the ion exchange layer, only the ion exchange layer was taken out and measured.

(Minimum temperature of relaxation time)
The minimum temperature of the relaxation time in the Na-type wet state ion exchange layer was determined by using time domain magnetic resonance (TD-NMR: Time Domain-Nuclear Magnetic Resonance) under the following conditions.
Device: mq-20 (Bruker BioSpin)
Measurement method: Inversion recovery
Measurement frequency: 19.95 MHz (1H nucleus)
Pulse repetition time: 7 seconds Measurement time: 20 minutes / temperature Measurement temperature: 203 to 313K (-70 to 40oC) 5K step analysis method: The obtained T1 relaxation curve is analyzed by the following formula, and the transition at each temperature is performed. The time T1 was calculated. The temperature showing the minimum T1 among the obtained T1s was defined as the minimum temperature of the relaxation time.

A: Strength, t: Time, T ₁ : T ₁ Relaxation time (filtration life)
As raw water, an aqueous solution having a calcium chloride concentration of 2 mmol / L and a sodium hydrogen carbonate concentration of 2 mmol / L was used, and the removal rate of calcium ions was measured. A 15 mL column was filled with 5 g of a Na-type wet ion exchanger, and raw water was passed therethrough so that the space velocity SV value was 500 (hr ^-1 ).

Raw water filters the filter 10bed vol. 10 mL was sampled for each permeation, and the calcium ion concentration in the permeated solution was measured by ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrum) to calculate the calcium ion removal rate. bed vol. Is the value obtained by dividing the volume of the permeate by the volume of the packed bed of 15 mL.
Bed vol. When the calcium ion removal rate reached 50%. Was defined as "filtration life".

(Example 1)
167 decitex, about 2 g of 48 filament PET fiber, 46.2 mass% polyacrylic acid 25,000 (manufactured by Wako Pure Chemical Industries, Ltd.), and 7.7 mass% polyglycerol polyglycidyl ether (Nagase Chemtex Co., Ltd.) The product was immersed in a 1 L aqueous solution containing EX-512). Next, the fiber was drained with a nozzle having a diameter of 430 μm and heated at 180 ° C. for 20 minutes. The obtained fibers were washed with running water and dried again by heating at 130 ° C. for 3 minutes. The obtained ion exchange fiber was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour, and the carboxy group was replaced with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Example 2)
167 decitex, about 2 g of 48 filament PET fiber, 46.2 mass% polyacrylic acid 25,000 (manufactured by Wako Pure Chemical Industries, Ltd.), and 7.7 mass% polyglycerol polyglycidyl ether (Nagase Chemtex Co., Ltd.) The product was immersed in a 1 L aqueous solution containing EX-512). Next, the fiber was drained with a nozzle having a diameter of 430 μm and heated at 200 ° C. for 20 minutes. The obtained fibers were washed with running water and dried again by heating at 130 ° C. for 3 minutes. The obtained ion exchange fiber was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour, and the carboxy group was replaced with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Example 3)
Acrylic acid 1.5 wt. To impart a functional group to 2 g of 167 decitex, 48 filament nylon fibers. %, Methacrylic acid 3.5 wt. %, APS 0.05 wt. %, Sodium hydroxymethane sulfinate 0.15 wt. %, Ethylenediamine tetraacetic acid 0.05 wt. It was immersed in 200 mL of a 70 ° C. aqueous solution for 1 hour and dried. Then, the obtained ion-exchange fiber heated at 180 ° C. for 20 minutes was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour to replace the carboxy group with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Example 4)
Acrylic acid 1.5 wt. To impart a functional group to 2 g of 167 decitex, 48 filament nylon fibers. %, Methacrylic acid 3.5 wt. %, APS 0.05 wt. %, Sodium hydroxymethane sulfinate 0.15 wt. %, Ethylenediamine tetraacetic acid 0.05 wt. It was immersed in 200 mL of a 70 ° C. aqueous solution for 1 hour and dried. Then, the obtained ion-exchange fiber heated at 200 ° C. for 20 minutes was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour to replace the carboxy group with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Example 5)
Acrylic acid 1.5 wt. To impart a functional group to 2 g of nylon fine particles having a particle size of 100 μm. %, Methacrylic acid 3.5 wt. %, APS 0.05 wt. %, Sodium hydroxymethane sulfinate 0.15 wt. %, Ethylenediamine tetraacetic acid 0.05 wt. It was immersed in 200 mL of a 70 ° C. aqueous solution for 1 hour and dried. Then, the obtained ion exchanger heated at 200 ° C. for 20 minutes was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour to replace the carboxy group with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Comparative Example 1)
Acrylic acid 1.5 wt. To impart a functional group to 2 g of nylon fine particles having a particle size of 100 μm. %, Methacrylic acid 3.5 wt. %, N, N'-methylenebisacrylamide 10 wt.%, APS 0.05 wt. %, Sodium hydroxymethane sulfinate 0.15 wt. %, Ethylenediamine tetraacetic acid 0.05 wt. It was immersed in 200 mL of a 70 ° C. aqueous solution for 1 hour and dried.
The obtained ion exchanger was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour to replace the carboxy group with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Comparative Example 2)
Acrylic acid 1.5 wt. To impart a functional group to 2 g of 167 decitex, 48 filament nylon fibers. %, Methacrylic acid 3.5 wt. %, N, N'-methylenebisacrylamide 10 wt.%, APS 0.05 wt. %, Sodium hydroxymethane sulfinate 0.15 wt. %, Ethylenediamine tetraacetic acid 0.05 wt. It was immersed in 200 mL of a 70 ° C. aqueous solution for 1 hour and dried.
The obtained ion exchange fiber was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour, and the carboxy group was replaced with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Comparative Example 3)
167 decitex, about 2 g of 48 filament PET fiber, 46.2 mass% polyacrylic acid 25,000 (manufactured by Wako Pure Chemical Industries, Ltd.), and 7.7 mass% polyglycerol polyglycidyl ether (Nagase Chemtex Co., Ltd.) The product was immersed in a 1 L aqueous solution containing EX-512). Next, the fiber was drained with a nozzle having a diameter of 430 μm and heated at 130 ° C. for 20 minutes. The obtained fibers were washed with running water and dried again by heating at 130 ° C. for 3 minutes. The obtained ion exchange fiber was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour, and the carboxy group was replaced with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Comparative Example 4)
167 decitex, about 2 g of 48 filament PET fiber, 46.2 mass% polyacrylic acid 25,000 (manufactured by Wako Pure Chemical Industries, Ltd.), and 7.7 mass% polyglycerol polyglycidyl ether (Nagase Chemtex Co., Ltd.) The product was immersed in a 1 L aqueous solution containing EX-512). Next, the fiber was drained with a nozzle having a diameter of 430 μm and heated at 240 ° C. for 20 minutes. The obtained ion exchanger was washed with running water and dried again by heating at 130 ° C. for 3 minutes. The obtained ion exchanger was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour to replace the carboxy group with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Comparative Example 5)
Acrylic acid 1.5 wt. To impart a functional group to 2 g of 167 decitex, 48 filament nylon fibers. %, Methacrylic acid 3.5 wt. %, APS 0.05 wt. %, Sodium hydroxymethane sulfinate 0.15 wt. %, Ethylenediamine tetraacetic acid 0.05 wt. It was immersed in 200 mL of a 70 ° C. aqueous solution for 1 hour and dried.
The obtained ion exchanger was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour to replace the carboxy group with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Comparative Example 6)
Acrylic acid 1.5 wt. To impart a functional group to 2 g of nylon fine particles having a particle size of 100 μm. %, Methacrylic acid 3.5 wt. %, APS 0.05 wt. %, Sodium hydroxymethane sulfinate 0.15 wt. %, Ethylenediamine tetraacetic acid 0.05 wt. It was immersed in 200 mL of a 70 ° C. aqueous solution for 1 hour and dried.
The obtained ion exchanger was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour to replace the carboxy group with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Comparative Example 7)
Acrylic acid 0.7 wt. To impart a functional group to 2 g of 167 decitex, 48 filament nylon fibers. %, Methacrylic acid 1.5 wt. %, APS 0.03 wt. %, Sodium hydroxymethane sulfinate 0.07 wt. %, Ethylenediamine tetraacetic acid 0.03 wt. It was immersed in 200 mL of a 70 ° C. aqueous solution for 1 hour and dried. Then, the obtained ion exchanger heated at 200 ° C. for 20 minutes was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour to replace the carboxy group with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

(Comparative Example 8)
Acrylic acid 0.7 wt. To impart a functional group to 2 g of nylon fine particles having a particle size of 100 μm. %, Methacrylic acid 1.5 wt. %, APS 0.03 wt. %, Sodium hydroxymethane sulfinate 0.07 wt. %, Ethylenediamine tetraacetic acid 0.03 wt. It was immersed in 200 mL of a 70 ° C. aqueous solution for 1 hour and dried. Then, the obtained ion exchanger heated at 200 ° C. for 20 minutes was immersed in a 0.1 mol / L sodium hydroxide aqueous solution for 1 hour to replace the carboxy group with a sodium type. Further, it was washed with RO water until the pH of the washing water became 8 or less. The performance of the obtained ion exchanger is shown in Table 1.

The ion exchange fiber of the present invention can be suitably used for hard water softening and pure water production.

Claims (6)

An ion exchanger including an ion exchange layer containing a crosslinked polymer compound having a cation exchange group.
The shape of the ion exchanger is either particles, fibers or sheets.
When the ion exchanger is in the form of particles, in a cross section that passes through the center of gravity of the ion exchanger and has the smallest area.
When the ion exchanger is fibrous, in a cross section perpendicular to its longitudinal direction,
When the ion exchanger is in the form of a sheet, in the cross section in the thickness direction thereof,
The area of the ion exchange layer occupies 30% or more of the total cross section, and
In the Na-type wet state, the ion exchange layer contains 50 (% by weight-absolute dry weight standard) or more of antifreeze water, 100 (% by weight-absolute dry weight standard) or less, and 2 (% by weight-weight%-) water having a lower melting point. A cation exchanger comprising 20 (% by weight-absolute dry weight standard) or more (absolute dry weight standard) or more. The cation exchanger according to claim 1, wherein when the ion exchange layer is in a Na-type wet state, the temperature at which the relaxation time measured by TD-NMR shows a minimum value is −15 ° C. or higher. .. The cation exchanger according to claim 1 or 2, wherein the cation exchange group is a carboxy group. The cation exchanger according to any one of claims 1 to 3, wherein the cation exchanger has a fibrous shape. Claims 1 to 1, wherein the cation exchanger includes a core material and an ion exchange layer which is arranged around the core material and contains a polymer compound having an ion exchange group. The cation exchanger according to any one of 4. The ion exchanger according to any one of claims 1 to 5, wherein the cation exchanger contains at least one polymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate and nylon.