JP5896486B2 - Nonwoven metal adsorbent and method for producing the same - Google Patents

Description

The present invention has a high adsorption capacity suitable for adsorption / recovery of metals in a wide range of solutions such as factory effluent, industrial water, environmental water, and manufacturing process water, has high chemical resistance, and is easy to diversify. The present invention relates to a non-woven metal adsorbent that can be processed into various forms and a method for producing the same.

It has been a long time since the creation of a recycling society was screamed. Separate collection and recycling of aluminum cans, steel cans, plastics such as PET, secondary batteries, papers, bottles, etc. are familiar, and the recycling rate is improving year by year. On the other hand, metal elements including rare metals such as rare earth elements, indium, niobium, manganese, platinum group, copper, zinc, aluminum, etc. are called “critical metals” and are extremely important key materials in high-tech industries. . Of these, copper, zinc, recycling systems such as aluminum has almost established, it does not stand still prospect of practical use with respect to other metal elements. The first reason for this is that the concentration of valuable metals in the waste and wastewater is low, so the efficiency in the extraction process is low. Another problem is that the process is complicated and costly, and that other than precious metals cannot be profitable. In view of the social circumstances surrounding metal resources, it is urgent to establish a system for collecting and recycling valuable metals, and at the same time, it is necessary to develop and establish efficient adsorption and separation techniques for valuable metals.

Generally, methods such as agglomeration, coprecipitation, solvent extraction, and particulate adsorbent are used for removing and collecting metals. In consideration of equipment, environmental load, and recycling, a method using a particulate adsorbent such as an ion exchange resin or a chelate resin is effective. In particular, chelate resins have higher affinity with metals than ion exchange resins, and thus can be said to be optimal metal adsorbents (Non-Patent Documents 1 to 3). Currently, various chelating resins such as iminodiacetic acid type, low molecular weight polyamine type, aminophosphoric acid type, and isothionium type are commercially available, but iminodiacetic acid type chelating resin applicable to a wide range of metal adsorption is mainly used. Has been. However, iminodiacetic acid-type chelate resins do not have a large complexing ability with metal elements, and in many cases, high recovery cannot be obtained in actual use. Moreover, since iminodiacetic acid type chelate resin also has a slow metal adsorption rate, it is difficult to treat a large amount of treated water quickly. Furthermore, since this iminodiacetic acid type chelate resin is in the form of particles, it must be used by filling a specific can body, and it is often difficult to apply depending on the use conditions and installation environment.

In order to solve the above-mentioned problems and respond to various demands, the chelate resin needs to further improve the metal adsorption characteristics, and it is necessary to study diversification of the adsorbent form. As one of the solutions to such a problem, research on a fibrous metal adsorbent is in progress as a chelate resin. In the fibrous adsorbent, since the adsorption site is limited to the fiber surface, the problem of diffusion resistance into the pores, which is often a problem with the particulate adsorbent in general, does not occur. Therefore, the fibrous adsorbent exhibits rapid adsorption / desorption characteristics, and since it is fibrous, it can be processed into a fabric (cloth, woven fabric, non-woven fabric, etc.) or paper, and can be further processed further. .

There are several disclosures about methods for producing fibrous adsorbents. Patent Document 1 discloses a method of introducing a chelating functional group into a fibrous member by a chemical grafting method. Patent Documents 2 and 3 disclose chelation on the surface of a fibrous member by radical generation / graft polymerization method by irradiation. Patent Document 4 discloses a method for introducing a functional functional group, and Patent Document 4 discloses a method for injecting a low-molecular chelating agent into a general-purpose fiber under high temperature and pressure. Although the fibrous adsorbent produced by these methods has a sufficient function and is presumed to be able to rapidly process the liquid to be treated, there is a problem in production. In the chemical grafting method, the types of fibers that can be grafted are limited and the manufacturing process is complicated. The radiation grafting method has an advantage that it can be applied to various fibers as compared with the chemical grafting method, but it is not a simple and inexpensive manufacturing method because it is a work in a specific environment from the viewpoint of radiation handling. Also, the chelating agent injection / impregnation method has an advantage that various fibers can be used, but the versatility is poor because it is impregnation under high temperature and high pressure.

Patent Document 5 and Patent Document 6 disclose a method for producing a fibrous metal adsorbent using a mixed spinning method. According to Patent Document 5, a long-chain ligand (a compound having a long molecular chain length and a metal-adsorbing ability) is added to polyvinyl alcohol, and after spinning by a wet method or a dry method, it is further formalized to form a fibrous metal. A method of manufacturing an adsorbent is disclosed, and this manufacturing method can manufacture a fibrous metal adsorbent at low cost and in large quantities using existing equipment. Further, according to Patent Document 6, a method for producing a fibrous metal adsorbent by wet spinning method by adding the same long-chain ligand as in Patent Document 5 to viscose is disclosed. Similarly to Patent Document 5, it is possible to produce a fibrous metal adsorbent at low cost and in large quantities using existing equipment. Since the fibrous metal adsorbent produced by these methods is fibrous, it is possible to produce a nonwoven fabric (see Patent Document 6), and various forms of metal can be obtained by further processing the resulting nonwoven fabric. It is possible to produce an adsorbent.
The fibrous metal adsorbents disclosed in Patent Document 5 and Patent Document 6 are easy to manufacture and use long-chain ligands, so that they are more complex than iminodiacetic acid-type chelate resins. In addition to showing ability, it has high element selectivity.
However, the fibrous metal adsorbent of the rayon base material manufactured in Patent Document 6 has the following problems. That is, the solution to be treated for metal recovery is generally an acidic solution containing hydrochloric acid, sulfuric acid, nitric acid and the like. For this reason, since rayon decomposes when exposed to a strongly acidic condition, the use of the fibrous metal adsorbent of the rayon base material is restricted under acidic conditions. Since rayon is also decomposed by microorganisms in the environment, the fibrous metal adsorbent of the rayon base material has a problem that it cannot withstand continuous use over a long period of time or a plurality of recycle uses.
Furthermore, the fibrous metal adsorbent of the polyvinyl alcohol base material disclosed in Patent Document 5 has the following problems. That is, polyvinyl alcohol is improved in acid resistance and alkali resistance by being formalized, but resistance to an organic solvent is not necessarily high. For this reason, the fibrous metal adsorbent of the polyvinyl alcohol base material has a problem that its application is limited to recovering and removing valuable metals (for example, a palladium catalyst for coupling reaction) in an organic solvent.

The fibrous adsorbent prepared by the above spinning method can be made into a non-woven fabric by a known method such as a needle punch method or a water jet method after opening using a roller card machine or the like, and further by secondary processing. It is possible to use various forms of adsorbents. However, such a method for producing a nonwoven fabric requires a multi-step process such as a spinning process, a fiber opening process, and a nonwoven fabric forming process, and the production process becomes complicated. Furthermore, in the nonwoven fabric prepared by such a method, the short fiber (lint) produced | generated in the opening process and the nonwoven fabric formation process is contained in a nonwoven fabric. In the metal recovery from the solution using the nonwoven fabric, since lint leaks into the treated water, it is necessary to remove lint from the adsorption treated water. For this reason, this removal process must be added to the metal recovery process. In particular, when the metal adsorbent produced by this nonwoven fabric production method is used for cleaning treatment of pure water, irrigation water, etc., leakage of lint into the treated water becomes a very serious problem.

As a countermeasure against lint leakage in the nonwoven fabric of the rayon base material, there is a method in which heat fusion fibers are mixed at the time of opening the obtained fibrous adsorbent material to form a nonwoven fabric, followed by heat treatment. By this heat treatment, the fibers are fixed by fusing with the heat-fusible fibers mixed with the fibrous metal adsorbent. Although the generation of lint is reduced by this method, the leakage of lint cannot be completely suppressed. Moreover, since the amount of the fibrous adsorbent per unit weight decreases due to the mixing of the heat-bonding fibers, the metal adsorption amount decreases.

JP 2001-113272 A Japanese Patent No. 4119966 Japanese Patent No. 3247704 JP 2007-247104 A JP 2011-056349 A JP 2011-056350 A

Hojo Masamasa, “Chelating Resins / Ion Exchange Resins”, Kodansha Scientific (1976). Manabu Senoo, Mitsuo Abe, Kaoru Suzuki, “Ion Exchange-Basics of Advanced Separation Technology”, Kodansha Scientific (1991). Supervised by Atsushi Kanzaki, Japan Ion Exchange Society, "All about cutting-edge ion exchange technology", Industrial Research Committee (2009).

The present invention has been made in view of the above problems, and is used for adsorption and recovery of metals in a solution. It has a high adsorption capacity, high chemical resistance, and various metal adsorption by chemical modification. Non-woven metal adsorbents that can be imparted with characteristics, can be manufactured using existing manufacturing equipment without using special equipment or complicated operations, and can be easily processed into various forms, and their manufacture It aims to provide a method.

As a result of intensive studies by the inventor of the present invention, a polymer having a glycidyl group and a polyolefin fiber matrix polymer having a flow start temperature of 200 ° C. or less are melt-mixed, and a melt blow method (also called a melt blown method) Alternatively, after forming a nonwoven fabric by the spunbond method, a long-chain metal arrangement having an amino group or an imino group on a glycidyl group present on the fiber surface of the nonwoven fabric or a halohydrin group formed by treating this glycidyl group with hydrogen halide. It has been found that by introducing a metal adsorbing functional group by reacting a ligand, a non-woven metal adsorbent having a high adsorption capacity, high chemical resistance and processable into various forms can be produced.

More specifically, the present invention relates to a nonwoven metal adsorbent described below and a method for producing the same.
1) Polymer having a glycidyl group having an epoxy value of 128 to 600 g / equivalent, polyethylene, polypropylene, poly [ethylene-vinyl acetate] having a flow initiation temperature of 200 ° C. or less, partially saponified poly [ Ethylene-vinyl acetate], and a polyolefin fiber matrix polymer selected from the group consisting of these mixtures, the mixing ratio of the polymer having a glycidyl group and the polyolefin fiber matrix polymer is 10: Melt and mix at 90-60: 40 to make a nonwoven fabric by the melt blow method or the spunbond method, and then react with a glycidyl group on the fiber surface of the nonwoven fabric to react with a long chain metal ligand having an amino group or an imino group to absorb metal Convert to halohydrin group by introducing a functional group or reacting this glycidyl group with hydrogen halide Nonwoven-like metal-adsorbing material is prepared by reacting a long-chain metal ligand introducing metal adsorbing functional group having an amino group or an imino group after.
2) The polymer having a glycidyl group is a homopolymer of a monomer selected from an acrylate ester having a glycidyl group or a methacrylate ester having a glycidyl group, or an acrylate ester having no glycidyl group and the glycidyl group, glycidyl A copolymer with a monomer selected from a methacrylic acid ester having no group or a vinyl aromatic monomer, and the molecular weight of the homopolymer or copolymer is 8,000 to 100,000 in terms of weight average molecular weight The non-woven fabric metal adsorbent according to 1) above, wherein
3) The long-chain metal ligand having an amino group or imino group is a polymer or polymer mixture selected from the group consisting of polyethyleneimine, polyallylamine, partial carboxymethylated products thereof, and mixtures thereof. The non-woven fabric metal adsorbent according to 1) above.
4) Polymer having a glycidyl group having an epoxy value of 128 to 600 g / equivalent, polyethylene, polypropylene, poly [ethylene-vinyl acetate] having a flow initiation temperature of 200 ° C. or less, partially saponified poly [ Ethylene-vinyl acetate], and a polyolefin fiber matrix polymer selected from the group consisting of these mixtures, the mixing ratio of the polymer having a glycidyl group and the polyolefin fiber matrix polymer is 10: After melt-mixing at 90-60: 40 and making it into a nonwoven fabric by the melt blow method or the spun bond method, it is reacted with a long-chain metal ligand having an amino group or an imino group on the glycidyl group on the fiber surface. Group or by reacting this glycidyl group with a hydrogen halide and converting it to a halohydrin group. A method of manufacturing a nonwoven fabric-like metal adsorbent Bruno by reacting long-chain metal ligand having a group or imino group introduced metal-adsorbing functional group,
A polymer or polymer mixture selected from the group consisting of polyethyleneimine, polyallylamine, partial carboxymethylated products thereof, and mixtures thereof is used as the long-chain metal ligand having an amino group or imino group. A method for producing a nonwoven metal adsorbent.
5) The polymer having a glycidyl group is a homopolymer of a monomer selected from an acrylate ester having a glycidyl group or a methacrylate ester having a glycidyl group, or an acrylate ester having no glycidyl group and glycidyl group, glycidyl A copolymer with a monomer selected from a methacrylic acid ester having no group or a vinyl aromatic monomer, and the molecular weight of the homopolymer or copolymer is 8,000 to 100,000 in terms of weight average molecular weight 4. A method for producing a non-woven metal adsorbent according to 4), wherein a certain one is used.

Here, as the polymer having a glycidyl group, one having an epoxy value of 128 to 600 g / equivalent is used. Here, examples of the polymer having a glycidyl group include a homopolymer of a monomer having a glycidyl group, or a copolymer of a monomer having a glycidyl group and a monomer having no glycidyl group.
Examples of the homopolymer include a homopolymer of an acrylate ester having a glycidyl group and a homopolymer of a methacrylic ester having a glycidyl group.
Examples of the copolymer include a copolymer of an acrylate monomer having a glycidyl group and an acrylate monomer having no glycidyl group, a methacrylate monomer having no glycidyl group, or a vinyl aromatic monomer, and a glycidyl group. And a copolymer of a methacrylic acid ester monomer having an acrylate monomer having no glycidyl group, a methacrylic acid ester monomer having no glycidyl group, or a vinyl aromatic monomer. As the molecular weight of the polymer having a glycidyl group, an average molecular weight (weight average molecular weight) of 8,000 to 100,000 is preferably used.

Examples of the polymer having a glycidyl group having an epoxy value of 128 to 600 g / equivalent include, for example, glycidyl acrylates, glycidyl acrylate homopolymer (epoxy value 128 g / equivalent), glycidyl methacrylate homopolymer (epoxy value 142 g / equivalent) Can be given. Examples of the copolymer include a copolymer of glycidyl methacrylate and styrene (polymerization ratio, glycidyl methacrylate: styrene = 20: 80, epoxy value of 544 g / equivalent), copolymer of glycidyl methacrylate and methyl methacrylate (polymerization ratio). In the case of glycidyl methacrylate: methyl methacrylate = 20: 80, the epoxy value is 542 g / equivalent). In the range where the epoxy value does not exceed 600, a high adsorption capacity is shown. However, if the epoxy value exceeds this, the adsorption capacity tends to decrease. Therefore, the one in the range not exceeding 600 can be most preferably used.

According to the present invention, a) a step of preparing a polymer having a glycidyl group in the molecule, b) kneading the polymer having a glycidyl group and a polyolefin fiber matrix polymer having a flow start temperature of 200 ° C. or lower. Step, c) Step of forming a nonwoven fabric by melt blow method or spun bond method, d) Amino group or imino group on the glycidyl group on the surface of the non-woven fiber, or a halohydrin group formed by reacting hydrogen halide with this glycidyl group By using a simple method of introducing a metal-adsorbing functional group by reacting a long-chain metal ligand having a group, the existing production equipment can be used as it is without improving the high adsorption capacity. It is possible to manufacture a non-woven metal adsorbent that has high chemical resistance and can be easily processed into various forms. The nonwoven metal adsorbent obtained by the present invention is rich in flexibility, and can be easily processed into a cylindrical form by tube winding, a laminated form by lamination, or a laminated form by folding (pleating). Thus, metal adsorbents having various forms suitable for valuable metal recovery and heavy metal removal can be produced. Moreover, since the nonwoven fabric-like metal adsorbent obtained by the present invention is sufficiently fused between fibers, it is difficult for lint to be generated, and it can also be used for cleaning treatment of pure water, irrigation water and the like. Furthermore, even after introducing a long-chain metal ligand having an amino group or imino group into a non-woven fabric mixed with a polymer having a glycidyl group, a reactive amino group is present in the long-chain metal ligand molecule. And the imino group remain, it is possible to change the metal adsorption property by further chemically modifying the remaining amino group or imino group by a secondary reaction.

An example of the manufacturing process of the nonwoven fabric-like metal adsorbent of the present invention is shown. The electron micrograph of the poly [ethylene-vinyl acetate] nonwoven fabric of 30 mass% mixing of acrylic polymer which has a glycidyl group obtained by Example 2 is shown. The relationship between the mixing ratio of the copolymer of glycidyl methacrylate and styrene and the copper adsorption capacity in the non-woven metal adsorbent mixed with the copolymer of glycidyl methacrylate and styrene obtained in Example 3 is shown. The relationship between the spinning temperature, copper adsorption capacity, and fiber diameter in the copolymer mixed nonwoven fabric-like metal adsorbent of glycidyl methacrylate and styrene obtained in Example 4 is shown. The electron micrograph of the poly [ethylene-vinyl acetate] nonwoven fabric-like metal adsorbent of 30% by mass of a copolymer of glycidyl methacrylate and styrene obtained at a spinning temperature of 190 ° C. and a spinning temperature of 220 ° C. in Example 4 is shown. . Here, FIG. A shows a case where the spinning temperature is 190 ° C., and FIG. B shows a case where the spinning temperature is 220 ° C. The relationship between the mixing ratio of the copolymer of glycidyl methacrylate and styrene and the copper adsorption capacity in the non-woven metal adsorbent mixed with the copolymer of glycidyl methacrylate and styrene obtained in Example 6 is shown. The electron micrograph of the 80% saponified poly [ethylene-vinyl acetate] nonwoven fabric-like metal adsorbent obtained by mixing 40% by mass of the glycidyl methacrylate and styrene copolymer obtained in Example 6 is shown.

FIG. 1 shows an example of the process for producing the nonwoven metal adsorbent of the present invention.
In this example, first, a fiber matrix obtained by kneading a polymer having a glycidyl group and a polyolefin fiber matrix polymer having a flow start temperature of 200 ° C. or less and mixing a polymer having a glycidyl group as a spinning raw material. A polymer material is prepared. Next, the fiber matrix polymer mixed with the polymer having the glycidyl group is formed into a nonwoven fabric by a melt blow method or a spun bond method. Then, a metal adsorbing functional group is introduced by reacting a long-chain metal ligand having an amino group or an imino group directly with the glycidyl group on the fiber surface of the obtained nonwoven fabric (polymer mixed nonwoven fabric having a glycidyl group). Or by reacting the glycidyl group with a hydrogen halide to form a halohydrin group, and reacting the generated halohydrin group with a long-chain metal ligand having an amino group or an imino group to introduce a metal-adsorptive functional group Thus, a non-woven metal adsorbent is obtained. The nonwoven metal adsorbent produced by this process has a high adsorption capacity of metal elements and high chemical resistance, and further changes to a nonwoven metal adsorbent with various metal adsorption characteristics by chemical modification. In addition, it can be easily processed into various forms such as pleating and tube winding.

In the present invention, a nonwoven fabric is produced by a melt blow method or a spun bond method. These methods use a low-melting-point thermoplastic resin (mainly polypropylene, polyethylene, etc.) as a raw material resin to produce a nonwoven fabric composed of fibers with a fiber diameter of sub-μm to several tens of μm, for example, 0.5 to 50 μm. can do. These manufacturing methods can obtain a nonwoven fabric by a series of processes, without opening using a roller card machine etc.
In the melt-blowing method, a nonwoven fabric is produced by blowing a thermoplastic resin from a nozzle installed after an extruder on a collection screen with a high-temperature and high-speed air stream. That is, the desired nonwoven fabric can be produced in one step without going through the steps of spinning, opening, and entanglement to make a nonwoven fabric. In addition, since the spun fibers are fused and cooled to solidify into a non-woven fabric, the manufactured non-woven fabric has high strength and is less likely to lint.
In the spunbond method, a molten thermoplastic resin is extruded from a nozzle installed after the extruder and spun, and the extruded fibers are superposed on a conveyor, and then the fibers are heat-sealed by a heat roller. Producing non-woven fabric. Since a nonwoven fabric composed of endless long fibers is produced by this method, the nonwoven fabric has high strength and dimensional stability and does not generate lint.
In general, the melt blow method is suitable for the production of a small amount of various types of nonwoven fabrics, and the spunbond method is suitable for the manufacture of a large amount of small types of nonwoven fabrics.
In the present invention, by using these methods, spinning and non-woven fabric can be performed at the same time or almost simultaneously. Therefore, after the pre-spun fibers are opened, the needle punch method, the water jet method, etc. It is possible to simplify the complicated process of making a nonwoven fabric by a technique. In addition, the nonwoven fabric obtained by these methods has a feature that lint does not occur or hardly occurs because fibers are sufficiently fused. Furthermore, these non-woven fabric forming methods also have the feature that the fibers constituting the non-woven fabric can be made into fine fibers, and a continuous roll-shaped non-woven fabric can be produced continuously.

The polymer having a glycidyl group used in the present invention is preferably a homopolymer of a vinyl monomer having a glycidyl group capable of reacting with an amino group or an imino group, or a copolymer with a monomer copolymerizable therewith. Can be mentioned.
Examples of the vinyl monomer having a glycidyl group include glycidyl methacrylate, glycidyl acrylate, and glycidoxymethylstyrene. One or more of these vinyl monomers having a glycidyl group may be used as a homopolymer or a copolymer of vinyl monomers having a glycidyl group.
Examples of the monomer having no glycidyl group that can be copolymerized with a vinyl monomer having a glycidyl group include styrene, methacrylic acid ester, acrylic acid ester, methacrylamide, and acrylamide.
However, when a copolymer having a high composition ratio of the monomer having no glycidyl group is used, the content of the glycidyl group is lowered, and as a result, the introduction amount of the metal-adsorbing functional group is lowered. The thing of 128-600 g / equivalent is used.
Moreover, when the molecular weight of the polymer having a glycidyl group is high, the brittleness becomes high, the kneadability and spinnability are lowered, and the metal adsorbent is low in flexibility. On the other hand, when the molecular weight is too low, it becomes difficult to uniformly knead with the fiber matrix polymer. In addition, when a metal-adsorbing functional group is introduced into a non-woven fabric produced using a material having a low molecular weight, there is a problem that the metal-adsorbing functional group is detached or eluted depending on use conditions. Therefore, in the present invention, it is preferable to use a polymer having an average molecular weight (weight average molecular weight) of 8,000 to 100,000.

In the present invention, examples of the fiber matrix polymer that is melt-mixed and spun with a polymer having a glycidyl group include polyolefin-based thermoplastic resins having a flow start temperature of 200 ° C. or lower. In general, since glycidyl groups are decomposed from about 250 ° C., the melt mixing spinning with a fiber base material having a flow start temperature exceeding 200 ° C. causes reduction or disappearance of glycidyl groups. Polyethylene, polypropylene, poly [ethylene-vinyl acetate], partially saponified poly [ethylene-vinyl acetate], or a mixture thereof is used as the fiber matrix polymer having a flow start temperature of 200 ° C. or less. However, non-woven fabrics prepared using partially saponified poly [ethylene-vinyl acetate] having a high degree of saponification, for example, partially saponified poly [ethylene-vinyl acetate] having a saponification degree exceeding 85%, are extremely Swells, part of the fusion between the fibers collapses, and there is a tendency for the tensile strength to decrease. Therefore, it is preferable to use partially saponified poly [ethylene-vinyl acetate] having a saponification degree of 85% or less. These fiber matrix polymers are not easily attacked by acids and alkalis in the general solution to be treated, and also have solvent resistance, so they can be used to prepare non-woven metal adsorbents with high chemical resistance and durability. Suitable as a fiber matrix polymer for. Further, since it has flexibility and can be fused with other polymers, it can be easily processed into various forms that can meet various needs.

The metal adsorption capacity of the nonwoven metal adsorbent of the present invention is determined by the mixing ratio (mixing ratio) of the polymer having a glycidyl group to the fiber matrix polymer and a long chain arrangement having an amino group or an imino group to be reacted with the glycidyl group. Depends on the amount of ligand introduced. When the mixing ratio of the polymer having a glycidyl group is low, the introduction amount of the long-chain ligand having an amino group or an imino group is lowered, and as a result, the metal adsorption capacity tends to be lowered. Accordingly, it is preferable that the mixing ratio of the polymer having a glycidyl group is high, but the polymer having a glycidyl group is highly brittle, and if the mixing ratio is increased, the spinnability may be lowered. Therefore, the mixing ratio of the polymer having a glycidyl group and the fiber matrix polymer is preferably 10:90 to 60:40, more preferably 20:80 to 50:50, as a mass ratio.

Introduction of the metal-adsorptive functional group into the polymer-mixed non-woven fabric having a glycidyl group is carried out by utilizing a reaction of a glycidyl group or a halohydrin group generated by reacting this glycidyl group with a hydrogen halide. Similarly, the epoxy group and halohydrin group of the glycidyl group are easily reacted with an amino group or an imino group. It can be said that the halohydrin group is a kind of a reactive derivative of an epoxy group. Various metal-coordinating low-molecular compounds that serve as metal-adsorbing functional groups are known, and among these metal-coordinating low-molecular compounds, there are many compounds that can easily react with glycidyl groups. However, when such a low molecular weight compound is introduced into the nonwoven fabric as a metal-adsorbing functional group, the short-chain length of the metal-adsorbing functional group derived from the short molecular chain length of the low-molecular compound causes The movement of this metal-adsorptive functional group moiety is very limited. Therefore, the chance of contact between the metal-adsorbing functional group and the metal element to be captured is low, and a quick adsorption characteristic is not necessarily obtained. Therefore, in the present invention, a long-chain metal ligand having an amino group or imino group is used. Examples of the long-chain ligand include polyethyleneimine, polyallylamine, partial carboxymethylated products thereof, and mixtures thereof.

The first form of a long-chain ligand having an amino group or an imino group for introducing a metal-adsorbing functional group into a polymer-mixed nonwoven fabric having a glycidyl group is a polyethyleneimine represented by Chemical Formula 1 (Chemical Formula 1) or It is a polyallylamine represented by Chemical Formula 2 (Chemical Formula 2). However, polyethyleneimine also produces a compound having a structure branched at the nitrogen site depending on the production method, and is sometimes commercially available as a mixture containing these branched compounds. Polyethyleneimine having a branched structure site can also react with the glycidyl group on the fiber surface, and a polyethyleneimine mixture containing polyethyleneimine having such a branched structure can also be used. In the present invention, polyethylene imine alone or further mixed with polyethylene imine having a branched structure is used as a long-chain ligand having an amino group or imino group to introduce a metal-adsorbing functional group into the nonwoven fabric. . These polyamines function as metal-adsorbing functional groups for transition metal elements, and also function as anion exchange groups to adsorb metal oxyanions such as molybdic acid and tungstic acid. It can also contribute to adsorption. Since these polyamines have a large number of amino groups or imino groups in the molecule, they react with multiple glycidyl groups on the fiber surface or with halohydrin groups formed by reacting glycidyl groups with hydrogen halide at multiple locations. It is possible. That is, it is presumed that a large number of metal coordination functional groups are introduced at a high density on the fiber surface because the metal-adsorbing functional groups are introduced in such a manner as to cover the fiber base material surface. Furthermore, by introducing polyamine in a covering manner, the water repellency based on the fiber base material is reduced (improves hydrophilicity), and the metal element in the aqueous solution can be efficiently adsorbed and recovered. Become.

Here, n is an integer of 2 or more, and the average molecular weight (weight average molecular weight) is 3,000 or less.

Here, m is an integer of 1 or more, and the average molecular weight (weight average molecular weight) is 3,000 or less.

The second form of the long-chain ligand having an amino group or imino group for introducing a metal-adsorbing functional group into a polymer-mixed non-woven fabric having a glycidyl group is represented by Chemical Formula 3 (Chemical Formula 3) and Chemical Formula 4 (Chemical Formula 4) 4) Partial carboxymethylation of the nitrogen atom of polyethyleneimine of chemical formula 1 (chemical formula 1) or polyallylamine of chemical formula 2 (chemical formula 2) so that the amino group or imino group shown in 4) remains. The degree of carboxymethylation of the partially carboxymethylated polyamine is not particularly specified, but there must be sufficient amino groups or imino groups to be introduced into the glycidyl groups in the fiber. Considering reaction efficiency and introduction rate, the degree of carboxymethylation is preferably 60% or less. In the present invention, these partially carboxymethylated polyamines may be used alone or in combination with two or more kinds of polyamines having different partial carboxymethylation, and if necessary, a long chain having an amino group or an imino group. It can be used by mixing with polyamine which is the first form of the type ligand. The basic metal adsorption properties of fully carboxymethylated polyamines are similar to iminodiacetic acid type ligands, but in the case of partially carboxymethylated polyamines, the amino groups that are not carboxymethylated or Since the imino group exists, the characteristics of the metal adsorbent into which the polyamine which is the first form of the present invention is introduced are also provided. Furthermore, the partially carboxymethylated polyamine has many imino groups and aminocarboxymethyl groups that are metal-adsorbing functional groups in one molecule, and is a long-chain type with a high degree of freedom. It is possible to prepare a metal adsorbent that is superior in both complex forming power and adsorption speed. As a method for partial carboxymethylation, a part of the amino group or imino group is protected with a protecting group in advance, and then carboxymethylated with a carboxymethylating reagent (usually halogenated acetic acid) by a known method, and then the protecting group is removed. The reaction may be carried out by reducing the ratio of the carboxymethylating reagent (usually halogenated acetic acid) used. By adjusting the degree of carboxymethylation, the selectivity to molybdic acid, tungstic acid, etc. can be improved. Even when a partially carboxymethylated polyamine is reacted, since there are a plurality of amino groups or imino groups, the fiber reacts with a plurality of glycidyl groups on the fiber surface in the same manner as in the first embodiment of the present invention. It is introduced so as to cover the surface of the base material.

Here, n1 and n2 are integers of 1 or more.

Here, m1 and m2 are integers of 1 or more.

Introducing a metal-adsorbing functional group into a polymer-mixed non-woven fabric having a glycidyl group is a method of stirring in a solution containing a long-chain ligand having an amino group or an imino group, or an amino group or an imino group. It can be performed by spraying a solution containing a long-chain ligand, or by immersing in a reaction bath filled with a solution containing a long-chain ligand having an amino group or imino group. Is possible. The nonwoven fabric forming method of the present invention has a feature that it can be continuously produced in the form of a long roll. Therefore, a continuous and easy adjustment of the reaction time is used for introduction of the metal-adsorbing functional group. Is effective. For example, when the immersion method is used, it is performed by immersing a polymer mixed nonwoven fabric having a glycidyl group in a solution containing a long-chain ligand having an amino group or an imino group for a certain period of time for reaction.
The long-chain ligand is bonded to a polymer having a glycidyl group by a reaction between an amino group or imino group of the long-chain ligand and a glycidyl group. At this time, since the long-chain ligand reacts with the glycidyl group appearing on the fiber surface, a metal-adsorbing functional group is introduced on the fiber surface. Thereby, it becomes a nonwoven fabric-like metal adsorbent with a high adsorption speed. In order to improve the reactivity between the polymer-mixed nonwoven fabric having glycidyl groups and the long-chain ligand, the polymer-mixed nonwoven fabric having glycidyl groups is treated with hydrohalic acid such as hydrochloric acid in advance to form glycidyl groups. It can also be halohydrinized. The halohydrination of the glycidyl group can be carried out by a known method using hydrochloric acid or hydrobromic acid as the hydrogen halide, but it is preferable to chlorohydrinate using hydrochloric acid that is easily available and handled. For example, chlorohydrin can be formed by immersing a polymer mixed nonwoven fabric having a glycidyl group in a 0.05 mol / L to 1 mol / L hydrochloric acid aqueous solution for 10 to 30 minutes. At this time, in order to shorten the reaction time, it may be heated to several tens of degrees Celsius. In addition, since the polyolefin polymer has strong water repellency, the reaction rate between the polymer-mixed nonwoven fabric having a glycidyl group and the long-chain ligand may be lowered. Therefore, dioxane or dimethylformamide may be added to a solution containing a long-chain ligand for improving reactivity. However, if the amount of dioxane or dimethylformamide added to the solution is increased, the polymer having a glycidyl group may be dissolved and eluted, so it is preferable to suppress the amount added to 20% (volume%) or less. The solution for dissolving the long-chain ligand may be an aqueous solution, but the polyolefin polymer is highly water-repellent, so the reaction rate of the polymer-mixed nonwoven fabric having a glycidyl group and the long-chain ligand may be lowered. is there. Therefore, the reaction is preferably performed in an alcohol solution or an aqueous solution containing alcohol so that the polymer having a glycidyl group does not dissolve or elute. Moreover, you may heat as needed. Since the introduction reaction of a long-chain ligand to a glycidyl group or a halohydrin group is relatively rapid, a polymer-mixed nonwoven fabric having a glycidyl group or a dip-type reaction tank filled with a solution of a long-chain ligand It is possible to introduce a long-chain ligand by immersing a polymer-mixed non-woven fabric having a large number of halohydrin groups produced by reacting glycidyl groups with hydrogen halide. As a matter of course, the long-chain ligand introduction step may be either a continuous type or a batch type. Unreacted glycidyl group or halohydrin group remains in the non-woven fabric after the reaction, but it is treated with alkali or acid to convert the glycidyl group or halohydrin group to a hydroxyl group, and the water repellency based on the fiber matrix polymer Can be further reduced.
In the present invention, the long-chain ligand reacts with the glycidyl group appearing on the fiber surface forming the polymer-mixed nonwoven fabric having a glycidyl group, so that a metal-adsorbing functional group is introduced on the fiber surface. However, a part of the polymer having a glycidyl group is incorporated in the fiber, and not all the glycidyl groups of the mixed polymer having a glycidyl group are exposed on the fiber surface. Therefore, a long-chain ligand cannot be introduced into all polymers having a glycidyl group. The amount of glycidyl groups which can be present and reacted on the fiber surface depends on the fiber diameter as well as the amount of the polymer having a glycidyl group mixed with the fiber matrix polymer. If the fiber diameter is small, the fiber surface area (specific surface area) per unit weight will increase, and as a result, the amount of reactive glycidyl groups per unit weight will increase, increasing the amount of metal adsorption per unit weight. Is possible. Also in this point, in the present invention, there is an advantage of using a melt blow method or a spun bond method capable of manufacturing a nonwoven fabric made of fibers having a fiber diameter of sub-μm to several tens of μm, for example, 0.5 to 50 μm.

The metal adsorption property of the nonwoven metal adsorbent of the present invention depends on the metal adsorption property of a long-chain metal ligand having an amino group or an imino group introduced into a nonwoven fabric mixed with a polymer having a glycidyl group. However, in a long-chain metal ligand molecule having an amino group or an imino group, a reactive amino group or imino group remains even after the introduction reaction into the nonwoven fabric. It is possible to change the metal adsorption property by introducing (chemically modifying) an additional functional group into this amino group or imino group by a secondary reaction. After introducing polyethyleneimine or polyallylamine, which is the first form of long-chain ligand having an amino group or imino group, into the nonwoven fabric, a carboxymethylation reagent (usually using a halogenated acetic acid) is used by a known method. May be used to carboxymethylate. Thereby, it is possible to convert to an aminocarboxylic acid type metal ligand such as iminodiacetic acid or ethylenediaminetetraacetic acid. This reaction can also be applied to partially carboxymethylated polyamines, and can be converted to metal adsorption properties closer to aminocarboxylic acid type metal ligands by carboxymethylation by a secondary reaction. In addition, when phosphonic acid and formaldehyde are reacted under hydrochloric acid acidity, a phosphomethyl group can be introduced into an amino group or an imino group, and the selectivity to rare earth can be improved. Furthermore, the selectivity to gold or platinum can be improved by reacting with acetic anhydride in a non-aqueous organic solvent to N-acetylate the amino group or imino group. Further, when the ion exchange capacity needs to be improved, a halogenated alkyl compound may be introduced into an amino group or imino group under alkaline conditions by a known method to form a quaternary ammonium group. Naturally, these reactions can also be applied to partially carboxymethylated polyamines, which makes it possible to prepare nonwoven metal adsorbents with multiple metal ligands with different properties. It becomes. In addition to secondary reactions of long-chain metal ligands having amino groups or imino groups, the remaining glycidyl groups after introduction of long-chain metal ligands have ionic functional groups such as amino groups, carboxyl groups, and sulfo groups, Furthermore, it is possible to improve the metal adsorption characteristics of the nonwoven metal adsorbent by introducing a low molecular ligand.

Next, although an Example demonstrates this invention, this invention is not limited at all by this Example.

(1) Kneading of a polymer having a glycidyl group and polyethylene A low-density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., LH902, flow start temperature: 107 ° C.) 7.0 kg and an acrylic high polymer having a glycidyl group 3.0 kg of molecules (manufactured by NOF Corporation, Marproof G-0150M, weight average molecular weight: 8,000 to 10,000, epoxy value: 310 g / equivalent) to a biaxial kneader (Toshiki Machine Co., Ltd., TEM26SS) The mixture was charged in a conventional manner, kneaded at 200 ° C., and a polyethylene pellet mixed with 30% by mass of an acrylic polymer having a glycidyl group was obtained with a pelletizer.

(2) The pellets obtained by melt spinning (1) were dried at 50 ° C. for 24 hours, and using this as a raw material, a spinning temperature of 190 ° C., an airflow temperature of 200 ° C., an airflow velocity of 155 m / sec, Melt blow spinning was performed under the condition of a nozzle hole diameter of 0.4 mm to obtain a polyethylene nonwoven fabric mixed with 30% by mass of an acrylic polymer having a glycidyl group with a basis weight of 65 g / m ² .

(3) Introduction of metal-adsorptive functional group Polyethylene non-woven fabric mixed with 30% by mass of acrylic polymer having glycidyl group obtained in (2) above is cut into a square of about 50 mm square with a cutting machine and kept at 40 ° C. It was immersed in an isopropyl alcohol solution containing 20% by mass of pentaethylenehexamine (manufactured by Wako Pure Chemical Industries, Ltd.) for 20 minutes to introduce pentaethylenehexamine. After the reaction, it was washed with pure water to obtain a non-woven metal adsorbent with pentaethylenehexamine introduced. The obtained nonwoven metal adsorbent was immersed in a 0.5 mol / L copper sulfate solution (pH 5.5) to adsorb copper. It was 0.52 mmol Cu / g when the amount of copper adsorption in a copper sulfate solution was measured with the atomic absorption photometer and the amount of copper adsorption was calculated | required. The nonwoven metal adsorbent used for this measurement was washed with 3 mol / L nitric acid to desorb the adsorbed copper, and then immersed in 1 mol / L nitric acid for 50 hours. After the immersion, the sample was sufficiently washed with water, and the copper adsorption amount was again determined by the same method as described above. The amount of metal adsorbed after the nitric acid immersion cleaning was 0.50 mmol Cu / g, and no performance degradation was observed in the strongly acidic solution. Moreover, although the nitric acid aqueous solution in which the nonwoven metal adsorbent was immersed and the rinse water after immersion were observed with a microscope, it was determined that no short fibers or fiber pieces were observed and no lint was generated.

In Example 1 (1) and (2), instead of low-density polyethylene (polyolefin fiber matrix polymer), poly [ethylene-vinyl acetate] (Mitsui / DuPont Polychemical Co., Ltd., Everflex EV420, flow start A poly [ethylene-vinyl acetate] non-woven fabric mixed with 30% by mass of acrylic polymer was prepared under the same conditions except that the temperature was 84 ° C. That is, an acrylic polymer having a glycidyl group with a weight per unit area of 65 g / m ² by performing a conventional melt blow spinning under conditions of a spinning temperature of 190 ° C., an air temperature of 200 ° C., an air velocity of 155 m / sec, and a nozzle hole diameter of 0.4 mm. A 30% by mass mixed poly [ethylene-vinyl acetate] nonwoven fabric was obtained. The electron micrograph of the obtained poly [ethylene-vinyl acetate] nonwoven fabric mixed with 30% by mass of the acrylic polymer having a glycidyl group is shown in FIG. Pentaethylenehexamine (manufactured by Wako Pure Chemical Industries, Ltd.) was introduced into the produced poly [ethylene-vinyl acetate] nonwoven fabric mixed with 30% by mass of the acrylic polymer having glycidyl groups by the same method as in Example 1 (3), and the nonwoven fabric. A metal adsorbent was prepared. The amount of copper adsorbed was 0.73 mmol Cu / g. Moreover, the performance fall after 50-hour immersion in 3 mol / L nitric acid was not confirmed, and lint was not observed.

In the same manner as in Example 2, the influence of the mixing ratio of the polymer having a glycidyl group was examined. The polyolefin fiber matrix polymer is the same poly [ethylene-vinyl acetate] as in Example 2, and the polymer having glycidyl group is a copolymer of glycidyl methacrylate and styrene (manufactured by NOF Corporation, Marproof G-0250S). , Weight average molecular weight: 20,000, epoxy value: 310 g / equivalent). The spinning conditions were the same as in Example 2. The mixing ratio of the polymer having a glycidyl group was 30% by mass, 40% by mass, 50% by mass, and 60% by mass. Tetraethylenepetamine (manufactured by Wako Pure Chemical Industries, Ltd.) was introduced into the poly [ethylene-vinyl acetate] non-woven fabric in which the copolymer of glycidyl methacrylate and styrene was mixed in the same manner as in Example 1 (3). A nonwoven metal adsorbent was prepared. The results are shown in FIG. As is apparent from the figure, the metal adsorption capacity increased by increasing the mixing ratio, and a metal adsorption capacity (copper adsorption capacity) of 1.32 mmol Cu / g was obtained at 60 mass%. However, the mixing rate and the metal adsorption capacity were not in a linear proportional relationship, and there was a tendency that the mixing rate was almost constant at a mixing rate of 50% by mass or more.

Comparative Example 1

Using the same fiber base material as in Example 3 and a polymer having a glycidyl group, a nonwoven fabric in which 70% by mass of a copolymer of glycidyl methacrylate and styrene was mixed under the same conditions as in Example 3 was produced. When the mixing ratio was 70% by mass, although spinning was possible, the degree of fusion between the fibers was low, and a uniform nonwoven fabric with sufficient strength could not be obtained. Attempts were made to introduce tetraethylenepetamine (manufactured by Wako Pure Chemical Industries, Ltd.) into this poly (ethylene-vinyl acetate) nonwoven fabric mixed with 70% by mass of this glycidyl methacrylate and styrene copolymer in the same manner as in Example 1 (3). It was. After being immersed in the 20% by mass tetraethylene petamine solution, a part of the fibers unraveled within a few minutes and could not be pulled up as a non-woven fabric after the reaction time (20 minutes) was completed.

Based on the results of Example 3, the influence of the spinning temperature was examined. The blend ratio of the same glycidyl methacrylate and styrene copolymer as in Example 3 was 30% by mass, and the same poly [ethylene-vinyl acetate] as in Example 2 was used as the fiber matrix polymer. The spinning conditions were spinning temperatures of 190 ° C, 200 ° C, 210 ° C and 220 ° C. The other conditions were as follows: at a spinning temperature of 190 ° C, an airflow temperature of 200 ° C, an airflow velocity of 155 m / sec, at a spinning temperature of 200 ° C, an airflow temperature of 210 ° C, an airflow velocity of 162 m / sec, and at a spinning temperature of 210 ° C, an airflow temperature of 220 ° C and an airflow velocity of 168 m. / Sec, at a spinning temperature of 220 ° C., an air flow temperature of 230 ° C., an air velocity of 175 m / sec, melt blow spinning under the conditions of a nozzle hole diameter of 0.4 mm, and a poly [ethylene-acetic acid mixed with 30% by mass of a glycidyl methacrylate-styrene copolymer Vinyl] nonwoven fabric was obtained. Tetraethylenepetamine (manufactured by Wako Pure Chemical Industries, Ltd.) was introduced into the produced poly [ethylene-vinyl acetate] nonwoven fabric mixed with 30% by mass of glycidyl methacrylate and styrene copolymer in the same manner as in Example 1 (3). A non-woven metal adsorbent was prepared. The results are shown in FIG. As is apparent in the figure, the metal adsorption capacity increased by increasing the spinning temperature, and a metal adsorption capacity of 1.22 mmol Cu / g at 210 ° C. and 1.32 mmol Cu / g at 220 ° C. was obtained. However, the spinning temperature and the metal adsorption capacity are not linearly proportional, and tend to be almost constant at a spinning temperature of 210 ° C. or higher. FIG. 5 shows an electron micrograph of a poly [ethylene-vinyl acetate] non-woven fabric mixed with 30% by mass of a copolymer of glycidyl methacrylate and styrene at a spinning temperature of 190 ° C. and a spinning temperature of 220 ° C. The higher the spinning temperature, the thinner the fiber diameter. As shown in FIG. 5b, the fiber diameter at the spinning temperature of 220 ° C. was about 15 μm.

Partially saponified poly [ethylene-vinyl acetate] (manufactured by Tosoh Corporation, Mersen H6822, flow starting temperature: 105 ° C.) having a saponification degree of 80% is used as the polyolefin fiber matrix polymer and has the same glycidyl group as in Example 1. 80% partially saponified poly [ethylene-vinyl acetate] non-woven fabric in which acrylic polymer is kneaded at a mixing ratio of 30% by mass, melt blown under the same conditions as in Example 2 and mixed with 30% by mass of acrylic polymer having a glycidyl group Got. The prepared 80% partially saponified poly [ethylene-vinyl acetate] nonwoven fabric mixed with 30% by mass of an acrylic polymer having a glycidyl group was immersed in a 0.1 mol / L hydrochloric acid aqueous solution for 30 minutes (40 ° C.) to convert the glycidyl group into chlorohydrin. After conversion to a group, partially carboxymethylated pentaethylenehexamine was introduced with reference to the method of Example 1 (3). Partially carboxymethylated pentaethylenehexamine is a 1 mol / L sodium hydroxide solution containing 40% by mass of pentaethylenehexamine (manufactured by Wako Pure Chemical Industries, Ltd.), pentaethylenehexamine and sodium monochloroacetate (manufactured by Wako Pure Chemical Industries, Ltd.). And sodium monochloroacetate was added so that the blending ratio (to the nitrogen molar ratio) was 1: 0.6, and the mixture was reacted at 40 ° C. for 4 hours. The obtained partially carboxymethylated pentaethylenehexamine solution was diluted twice with pure water, and an 80% partially saponified poly [ethylene-vinyl acetate] non-woven fabric mixed with 30% by mass of an acrylic polymer having a chlorohydrinized glycidyl group was obtained. It was immersed and reacted at 40 ° C. for 20 minutes. It was observed that the fibers swelled slightly during the reaction, but after the reaction, the 80% partially saponified poly [ethylene-vinyl acetate] non-woven metal adsorbent mixed with 30% by mass of acrylic polymer having a glycidyl group. There was no decrease in mechanical strength. The metal adsorption capacity (copper adsorption capacity) of an 80% partially saponified poly [ethylene-vinyl acetate] nonwoven fabric metal adsorbent mixed with 30% by mass of an acrylic polymer having a glycidyl group was 0.48 mmol Cu / g.

Comparative Example 2

In Example 5, instead of partially saponified poly [ethylene-vinyl acetate] having a saponification degree of 80% as a fiber matrix polymer, partially saponified poly [ethylene-vinyl acetate] having a saponification degree of 90% (manufactured by Tosoh Corporation, 90% partially saponified poly [ethylene-vinyl acetate] non-woven fabric mixed with 30% by mass of an acrylic polymer having a glycidyl group under the same conditions as in Example 5 except that Mersen H6960, flow start temperature: 118 ° C. Produced. Thereafter, in the same manner as in Example 5, partially carboxymethylated pentaethylenehexamine was introduced into a 90% partially saponified poly [ethylene-vinyl acetate] nonwoven fabric mixed with 30% by mass of an acrylic polymer having a glycidyl group. In the 90% partially saponified poly [ethylene-vinyl acetate] nonwoven fabric mixed with 30% by mass of the acrylic polymer having glycidyl groups, extreme swelling of the fibers was observed when chlorohydrinized and partially carboxymethylated pentaethylenehexamine was introduced. During the partially carboxymethylated pentaethylenehexamine introduction reaction, a part of the fiber was loosened. After the reaction, although it was able to be pulled up as a nonwoven fabric, the mechanical strength was clearly reduced and it was easily torn. The metal adsorption capacity (copper adsorption capacity) of 90% partially saponified poly [ethylene-vinyl acetate] non-woven fabric mixed with 30% by mass of acrylic polymer having glycidyl group was 80 of 30% by mass of acrylic polymer having glycidyl group. % Partially saponified poly [ethylene-vinyl acetate] non-woven fabric was 0.44 mmol Cu / g slightly lower.

Based on the results of Example 5, the influence of the mixing ratio of the polymer having a glycidyl group was examined using partially saponified poly [ethylene-vinyl acetate] having a saponification degree of 80%. As the polymer having a glycidyl group, the same copolymer of glycidyl methacrylate and styrene as in Example 3 was used. The mixing ratio of the polymer having a glycidyl group was 20% by mass, 30% by mass, and 40% by mass. Spinning conditions were: Spinning temperature of 160 ° C., air flow temperature of 200 ° C., air flow speed of 155 m / sec, nozzle hole diameter of 0.4 mm, melt blend spinning with a basis weight of 65 g / m ² glycidyl methacrylate and styrene copolymer mixture part A saponified poly [ethylene-vinyl acetate] nonwoven fabric was obtained.
In the same manner as in Example 1 (3), tetraethylenehexamine (manufactured by Wako Pure Chemical Industries, Ltd.) was introduced into the produced glycidyl methacrylate and styrene copolymer mixed partially saponified poly [ethylene-vinyl acetate] non-woven fabric. A metal adsorbent was prepared. The results are shown in FIG. As is clear from the figure, the metal adsorption capacity (copper adsorption capacity) was increased by increasing the mixing ratio, and a metal adsorption capacity of 0.67 mmol Cu / g was obtained at a mixing ratio of 40% by mass. Although the metal adsorption capacity was lower than that in the case of using unsaponified poly [ethylene-vinyl acetate] in Example 3, even if partially saponified poly [ethylene-vinyl acetate] having a saponification degree of 80% was used, sufficient metal was used. A non-woven metal adsorbent having an adsorption capacity could be obtained. FIG. 7 shows an electron micrograph of a partially saponified poly [ethylene-vinyl acetate] nonwoven fabric obtained by mixing 40% by mass of a glycidyl methacrylate / styrene copolymer obtained in this example.

In Example 1 (1), the polyolefin fiber matrix polymer was changed to polypropylene (Nippon Polypro Corporation, Novatec PP SA3A, flow start temperature: 176 ° C.), and an acrylic polymer having a glycidyl group was used. Polypropylene pellets mixed with 30% by mass of an acrylic polymer having a glycidyl group were obtained. The spinning conditions were as follows: a spinning temperature of 220 ° C., an air temperature of 230 ° C., an air speed of 175 m / sec, melt blow spinning under the conditions of a nozzle hole diameter of 0.4 mm, and a polypropylene nonwoven fabric mixed with 30% by mass of an acrylic polymer having a glycidyl group. Produced. Tetraethylenepetamine (manufactured by Wako Pure Chemical Industries, Ltd.) was introduced into the obtained nonwoven fabric in the same manner as in Example 1 (3) to prepare a nonwoven metal adsorbent. The metal adsorption capacity (copper adsorption capacity) of polypropylene nonwoven fabric mixed with 30% by mass of acrylic polymer having glycidyl group is 0.49 mmol Cu / g, and 30% by mass of acrylic polymer having glycidyl group of Example 1 is mixed. It was almost the same as the case of the polyethylene nonwoven fabric.

Comparative Example 3

Polymethylpentene (manufactured by Mitsui Chemicals, TPX DX845, flow start temperature: 239 ° C.) as a polyolefin fiber matrix polymer, and an acrylic polymer having the same glycidyl group as in Example 1 as a polymer having a glycidyl group An attempt was made to produce a polymethylpentene nonwoven fabric mixed with 30% by mass of an acrylic polymer having a glycidyl group. With a kneading temperature of 260 ° C., polymethylpentene pellets mixed with 30% by mass of an acrylic polymer having a glycidyl group were obtained in the same manner as in Example 1 (1). The obtained pellets were markedly yellowed, the extreme decomposition of the acrylic polymer having a glycidyl group had progressed, and the yarn could not be made into a nonwoven fabric without spinnability.

Looking at the results of Example 1 to Example 7, all of the nonwoven metal adsorbents obtained in Examples 1 to 7 have a high metal adsorption capacity and are shown in Example 1 (3). Even after the nitric acid immersion test, no decrease in metal adsorption capacity was observed. In addition, in the nitric acid immersion test, the nitric acid aqueous solution in which the nonwoven fabric-like metal adsorbent was soaked and the washing water after immersion were observed with a microscope. No fiber fragments were observed, and no lint was observed.

According to the present invention, a) a step of preparing a polymer having a glycidyl group in the molecule, b) a step of kneading the polymer having a glycidyl group and a polyolefin fiber matrix polymer having a flow initiation temperature of 200 ° C. or less. C) a step of forming a non-woven fabric by a melt blow method or a spun bond method, d) an amino group or an imino group on a glycidyl group on the surface of the non-woven fiber, or a halohydrin group formed by reacting this glycidyl group with a hydrogen halide. It has a high adsorption capacity by using the existing production equipment as it is without improving the existing manufacturing equipment by a simple method of introducing a metal-adsorbing functional group by reacting with a long-chain metal ligand. It is possible to produce a non-woven metal adsorbent that has high chemical resistance and can be easily processed into various forms. The nonwoven metal adsorbent obtained by the present invention is rich in flexibility and can be easily processed into a cylindrical form by tube winding, a laminated form by lamination, or a laminated form by folding (pleating). Thus, metal adsorbents having various forms suitable for valuable metal recovery and heavy metal removal can be produced. In addition, the non-woven metal adsorbent obtained by the present invention has sufficient strength between the fibers, so that it has sufficient strength and hardly generates lint and is used for cleaning treatment such as pure water and water. It is also possible to use it. Furthermore, it is possible to change the metal adsorption characteristics by chemically modifying the amino group or imino group remaining in the long-chain metal ligand having an amino group or imino group introduced into the nonwoven fabric by a secondary reaction. It is.

Claims (2)

A polymer having a glycidyl group having an epoxy value of 128 to 600 g / equivalent, polyethylene, polypropylene, poly [ethylene-vinyl acetate] having a flow initiation temperature of 200 ° C. or lower, and partially saponified poly [ethylene-ethylene having a saponification degree of 85% or lower. Vinyl acetate], and a polyolefin fiber matrix polymer selected from the group consisting of these mixtures, the mixing ratio of the polymer having a glycidyl group and the polyolefin fiber matrix polymer in a mass ratio of 10:90 to After melt-mixing at 60:40 to form a nonwoven fabric by the melt blow method or the spun bond method, it is reacted with a long-chain metal ligand having an amino group or an imino group on the glycidyl group on the fiber surface of the nonwoven fabric to form a metal-adsorbing functional group. The glycidyl group was reacted with a hydrogen halide to convert it to a halohydrin group. A method of amino group or by reacting a long-chain metal ligand having an imino group by introducing a metal adsorbing functional group to produce a nonwoven fabric-like metal-adsorbing material,
A polymer or polymer mixture selected from the group consisting of polyethyleneimine, polyallylamine, partial carboxymethylated products thereof, and mixtures thereof is used as the long-chain metal ligand having an amino group or imino group. A method for producing a nonwoven metal adsorbent. The polymer having a glycidyl group is a homopolymer of a monomer selected from an acrylate ester having a glycidyl group or a methacrylate ester having a glycidyl group, or an acrylate ester having no glycidyl group and a glycidyl group. A copolymer with a monomer selected from methacrylic acid ester or vinyl aromatic monomer which does not have, and the molecular weight of these homopolymer or copolymer is 8,000 to 100,000 in terms of weight average molecular weight The method for producing the nonwoven metal adsorbent according to claim 1, wherein: