JP2015030731A - Ethylene-vinyl alcohol-based graft copolymer, production method thereof and semimetal adsorption - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel ethylene-vinyl alcohol-based graft copolymer excellent in adsorptivity of semimetals, e.g. boron, its production method and a semimetal adsorbent using it.SOLUTION: An ethylene-vinyl alcohol-based graft copolymer consists of a base material component composed of an ethylene-vinyl alcohol-based copolymer and a graft chain which is introduced into the base material component and has an N-methylglucamine. The graft copolymer is obtained by a production method including a step of preparing the ethylene vinyl alcohol-based copolymer and a step of introducing the graft chain having the N-methylglucamine group into the copolymer to obtain the graft copolymer introduced with the graft chain having the N-methylglucamine group. The graft copolymer is useful as a semimetal adsorbent for boron, etc.

Description

  The present invention relates to an ethylene-vinyl alcohol-based graft copolymer into which a graft chain having an N-methylglucamine group is introduced, a method for producing the same, and a semimetal adsorbent using the ethylene-vinyl alcohol-based graft copolymer About.

  Metalloid compounds such as boron, arsenic, and germanium may be contained in hot springs, seawater, factory wastewater, mine wastewater, and the like. For example, boron compounds are used in various industrial products such as pharmaceuticals, cosmetics, soaps, electroplating, glass, etc., and not only the stage for producing boron compounds used in these applications but also boron compounds are used. In addition, boron-containing wastewater is also generated in the stage of incineration and disposal of products containing used boron compounds, as well as in wastewater from various power plants and flue gas desulfurization wastewater.

  The effect of boron on the human body is not clear, but vomiting and abdominal pain, neurotoxicity and growth inhibition due to inoculation of high-concentration solutions have been observed.

  From such a background, since 2001, according to the Water Pollution Control Law, the drainage standard for boron and its compounds outside the sea has been set to 10 mg / L. However, since there is no effective and inexpensive treatment technique, it is in a situation that is a provisional standard, and technical improvement of boron-containing water treatment is required.

  As existing treatment technologies for water containing metalloids such as boron, a coagulation precipitation method, membrane separation, electrical separation, a method using a metalloid adsorbent, and the like have been proposed. In particular, the method of adsorbing and recovering a semimetal using a semimetal adsorbent utilizes the property that a semimetal such as boron forms a complex with a plurality of hydroxyl group-containing compounds.

  Metalloid ion adsorbents are materials that use a property that boron or arsenic generally forms a complex with a compound containing a plurality of hydroxyl groups. As a resin in which a functional group containing a hydroxyl group is introduced into an insoluble polymer, For example, Patent Document 1 discloses a boron adsorbent using a polyol chitin / chitosan derivative crosslinked by electron beam irradiation as a raw material.

  As a means for increasing the amount of metalloid adsorption, a technique for increasing the amount of functional group introduction using a graft polymerization technique is known. For example, Patent Document 2 discloses that a chelate-forming group is introduced into a graft chain introduced by electron beam irradiation graft polymerization into a highly crystalline particulate crystalline cellulose base material.

  Furthermore, in order to increase the amount of graft chains and increase the adsorption capacity, Patent Document 3 discloses that a base material serving as a nucleus is present by preparing a radical polymerization initiator by irradiating polymer particles with radiation. A method for producing an adsorptive polymer is disclosed.

JP 2008-104956 A JP 2009-013204 A JP 2013-006942 A

  However, the adsorbent made from the polyol chitin / chitosan derivative disclosed in Patent Document 1 has a drawback that the amount of functional groups is small and the amount of boron adsorbed is small.

  Moreover, although the crystalline cellulose currently disclosed by patent document 2 has implemented the functional group introduction by graft polymerization, since the cellulose is used as a base material, the stability of the radical generate | occur | produced by the electron beam irradiation is carried out. Since the graft ratio of the graft body is low and tends to fluctuate, there is a concern that the performance is likely to vary. Furthermore, since the crystalline crystalline cellulose itself is expensive, there are restrictions on actual use.

  Further, in Patent Document 3, the particles are used by changing the particles directly into radical polymerization initiators by irradiating the very small particles with radiation. In such a case, the radicals in a very unstable state are used. Since a polymerization initiator is used, not only the stability of the reaction is low, but also the shape of the resulting adsorptive polymer cannot be controlled. Furthermore, since the base material component no longer exists in the obtained radical polymer, the characteristics of the base material component cannot be utilized.

Accordingly, an object of the present invention is to have an ethylene-vinyl alcohol copolymer as a base material component, and an N-methylglucamine group is introduced into this base material component and has a good adsorptivity to a metalloid. It is to provide a graft copolymer.
Another object of the present invention is to provide a method for producing a graft copolymer in which graft chains are simply introduced even under room temperature conditions in the atmosphere using a graft copolymerization technique using ionizing radiation. .
Still another object of the present invention is to provide a semi-metal adsorbent using the graft copolymer.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have introduced (i) a graft chain having an N-methylglucamine group using an ethylene-vinyl alcohol copolymer as a base component. (Ii) Surprisingly, the ethylene-vinyl alcohol copolymer can introduce a graft chain more easily than other polymers (for example, polyethylene and cellulose), and achieves a high functional group introduction amount. It was found that a polymer can be obtained and the obtained graft copolymer has a high metalloid adsorption performance.

  In addition, (iii) by controlling the shape of the ethylene-vinyl alcohol copolymer as a base material component to a predetermined shape, (iv) the adsorption performance of the resulting graft copolymer can be further improved, (v) The present inventors have also found out that the handleability of the obtained graft copolymer and its filtration performance can be improved, thereby completing the present invention.

That is, the first configuration of the present invention is a base component composed of an ethylene-vinyl alcohol copolymer,
This is an ethylene-vinyl alcohol-based graft copolymer composed of a graft chain having an N-methylglucamine group introduced to the base material component.

  In the graft copolymer, the amount of N-methylglucamine groups introduced may be 0.7 mmol / g or more.

  The graft copolymer is preferably a porous body. For example, the major axis of the pores formed on the surface of the porous body may be 0.01 μm to 20 μm.

  The graft copolymer may be in the form of particles having a particle size of 30 μm to 5000 μm.

  The second configuration of the present invention is a step of preparing an ethylene-vinyl alcohol copolymer (step A), and a graft chain having a methylglucamine group is introduced into the ethylene-vinyl alcohol copolymer. And a step of obtaining a graft copolymer into which a graft chain having a methylglucamine group has been introduced (step B). A method for producing an ethylene-vinyl alcohol-based graft copolymer.

  The ethylene-vinyl alcohol copolymer prepared in the step A may be a porous body. In step A, an ethylene-vinyl alcohol copolymer and a water-soluble polymer (for example, polyvinyl alcohol) are melt-mixed, and the mixed melt is cooled and solidified, whereby an ethylene-vinyl alcohol-based copolymer is obtained. Preferably, the method includes a step of obtaining a complex containing a water-soluble polymer and a step of extracting a water-soluble polymer from the complex to obtain a porous body.

  In the step B, a graft chain may be introduced using ionizing radiation. In this case, after irradiation with ionizing radiation, the irradiated object can be left in air at room temperature for a predetermined time (for example, not less than 10 minutes and not more than 2 hours).

  The third configuration of the present invention is a metalloid adsorbent using the graft copolymer.

  In the first configuration of the present invention, by using an ethylene-vinyl alcohol copolymer as a base component, a graft copolymer having a graft chain having an N-methylglucamine group is obtained with a high functional group introduction amount. be able to.

  In the second configuration of the present invention, an ethylene-vinyl alcohol-based graft copolymer can be efficiently produced by using an ethylene-vinyl alcohol-based copolymer as a starting material. In particular, when a graft chain is introduced using ionizing radiation, radicals generated in the ethylene-vinyl alcohol copolymer are lost even at room temperature and atmospheric conditions even if the polymerization is carried out by irradiation with ionizing radiation at room temperature. Since it is difficult to activate, a graft chain can be easily and stably introduced, and a high functional group introduction amount can be achieved. In addition, when a porous ethylene-vinyl alcohol copolymer is used, the amount of functional groups introduced can be further increased.

  In the third configuration of the present invention, various metalloids can be efficiently adsorbed by the metalloid adsorbent using such an ethylene-vinyl alcohol-based graft copolymer.

  Hereinafter, embodiments of the present invention will be specifically described. Note that the embodiments described below do not limit the present invention. Further, unless otherwise specified, the state before the graft chain is introduced is expressed as an ethylene-vinyl alcohol copolymer, and the state after the graft chain is introduced is expressed as an ethylene-vinyl alcohol graft copolymer. .

(Graft copolymer)
The first configuration of the present invention is composed of a base component composed of an ethylene-vinyl alcohol copolymer and a graft chain having an N-methylglucamine group introduced to the base component. Graft copolymer.

  From the viewpoint of achieving a high degree of adsorptivity, the above graft copolymer preferably has an N-methylglucamine group introduction amount of 0.7 mmol / g or more with respect to the ethylene-vinyl alcohol copolymer. More preferably, it is 0.5 mmol / g or more, more preferably 1.9 mmol / g or more, and most preferably 2.1 mmol / g or more. If the amount introduced is too small, the amount of functional metal introduced may be too small to obtain the target metalloid adsorption amount.

The aforementioned graft copolymer may be a porous body. The porous body only needs to have pores formed at least on the surface of the ethylene-vinyl alcohol copolymer, and does not need to have pores formed inside the ethylene-vinyl alcohol copolymer. It has a structure containing at least 10, preferably 100 or more, and more preferably 1,000 or more pores having a major axis of 0.01 to 20 μm per 1 cm ^{2 of} area.

  When pores are formed on the surface of the ethylene-vinyl alcohol-based graft copolymer, the average value of the major axis is preferably 0.01 μm to 20 μm, more preferably 0.05 μm to 10 μm, and further preferably 0.1 μm to 8 μm. Preferably, 0.2-5 micrometers is the most preferable. The major axis of these pores is a value measured by the method described in Examples described later. Among them, the use of a porous material having large pores facilitates efficient adsorption on the adsorptive functional groups in the pores, so that the intended semimetal adsorption performance is easily obtained.

  The shape of the above-mentioned graft copolymer is not particularly limited, and depending on the application location of the graft copolymer, various kinds of fibers, aggregates of woven fabrics and nonwoven fabrics, particles, sheets, films or processed products thereof can be used. You can choose from shapes. Among these, from the viewpoint of improving the adsorptivity with the semimetal, a particulate shape is preferable. In the present invention, the term “particle” is a concept including powder.

  When the above-mentioned graft copolymer is in the form of particles, it may be adjusted to the desired particle size by pulverization as necessary, but the particle size is preferably 30 μm to 5000 μm, more preferably 60 μm to 4500 μm, and more preferably 100 μm to 4000 μm Most preferred. If the particle size is too small, handling is difficult, for example, the fine powder is likely to fly.

  In particular, in the ethylene-vinyl alcohol graft copolymer of the present invention, the amount of methylglucamine groups introduced can be increased even when the particle size is somewhat large. In addition to excellent properties, the filtration performance can be improved.

  The second configuration of the present invention is a step of preparing an ethylene-vinyl alcohol copolymer (step A), and a graft chain having a methylglucamine group is introduced into the ethylene-vinyl alcohol copolymer. And a step of obtaining a graft copolymer into which a graft chain having a methylglucamine group has been introduced (step B). A method for producing an ethylene-vinyl alcohol-based graft copolymer.

(Ethylene-vinyl alcohol copolymer)
The ethylene-vinyl alcohol copolymer used as the base material of the graft copolymer of the present invention is not particularly limited as long as a graft copolymer having the above properties can be obtained. For example, the ethylene content is 10 to 60 mol% is preferable, and about 20 to 50 mol% is more preferable. When the ethylene content is less than 10 mol%, the water resistance of the obtained graft copolymer may be lowered. On the other hand, when the ethylene content exceeds 60 mol%, it is difficult to produce and difficult to obtain.

  The saponification degree of the ethylene-vinyl alcohol copolymer is preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 99 mol% or more. When the degree of saponification is less than 90 mol%, the moldability may be deteriorated or the water resistance of the obtained graft copolymer may be lowered.

  Further, the melt flow rate (MFR) (210 ° C., load 2160 g) of the ethylene-vinyl alcohol copolymer is not particularly limited, but is preferably 0.1 g / 10 minutes or more, more preferably 0.5 g / 10 minutes or more. preferable. If it is less than 0.1 g / 10 min, water resistance and strength may be reduced. In addition, the upper limit of a melt flow rate should just be the range normally used, for example, may be 25 g / 10min or less.

The ethylene-vinyl alcohol copolymer of the present invention may contain another unsaturated monomer unit as long as the effects of the present invention are not impaired. The content of the unsaturated monomer unit is preferably 10 mol% or less, more preferably 5% mol or less.
Such ethylene-vinyl alcohol copolymers can be used alone or in combination of two or more.

  The ethylene-vinyl alcohol-based copolymer may have various shapes such as a film, a sheet, a container, particles, and a powder depending on the use when introducing the graft chain.

  As a method for introducing a graft chain having an N-methylglucamine group into the above ethylene-vinyl alcohol copolymer, various known methods are possible. For example, radicals using a polymerization initiator are used. Examples thereof include a method of introducing a graft chain using polymerization, a method of generating a radical using ionizing radiation, and introducing a graft chain.

  Among these, from the viewpoint of high graft chain introduction efficiency, a method of introducing a graft chain using ionizing radiation is preferably used. In particular, it has been clarified that the ethylene-vinyl alcohol copolymer has high stability of radicals generated by ionizing radiation irradiation, as shown in Examples described later.

  In particular, even after ionizing radiation irradiation, the ethylene-vinyl alcohol copolymer maintains radicals in air at room temperature (for example, about 15 to 35 ° C.) for about 1 to 2 hours. The graft chain can be introduced by bringing the ethylene-vinyl alcohol copolymer into contact with an unsaturated monomer as shown below in the presence of air.

  In general, in the graft polymerization to ordinary polymers such as polyethylene and cellulose, the irradiation step and the graft chain introduction step are continuously performed in an inert atmosphere and / or under refrigeration (or contacted with an unsaturated monomer immediately after irradiation). Step) is necessary, but it is not necessary for the ethylene-vinyl alcohol copolymer, and it is possible to widen the allowable range of the process in industrial production.

  When introducing a graft chain having an N-methylglucamine group, polymerization of an unsaturated monomer in the presence of an ethylene-vinyl alcohol copolymer (for example, chain transfer method, polymer initiator method, radiation graft method, A graft chain may be introduced by a mechanical chemical reaction method) or a graft chain may be introduced by a binding reaction or exchange reaction between polymers. Further, the unsaturated monomer may be an unsaturated monomer having an N-methylglucamine group, or an unsaturated monomer having a group reactive to N-methylglucamine. It may be.

  Among these, from the viewpoint of efficiently introducing a graft chain, it is preferable that an unsaturated monomer having a reactive group is grafted using ionizing radiation and then converted to an N-methylglucamine group.

  Examples of the ionizing radiation include α rays, β rays, γ rays, accelerated electron rays, ultraviolet rays, and the like. Practically, accelerated electron rays or γ rays are preferable.

  As a method of graft polymerization of unsaturated monomer to the base material of ethylene-vinyl alcohol copolymer using ionizing radiation, simultaneous irradiation method of irradiating radiation in the coexistence of base material and unsaturated monomer Any of the pre-irradiation methods in which the unsaturated monomer and the substrate are brought into contact with each other after irradiation with the substrate in advance is possible, but the pre-irradiation method is used from the viewpoint of suppressing side reactions other than graft polymerization. Is desirable.

  In the graft polymerization, the substrate and the unsaturated monomer are brought into contact with each other as a liquid phase polymerization method in which the substrate is brought into direct contact with a liquid unsaturated monomer or an unsaturated monomer solution, and an unsaturated monomer. There is a gas phase graft polymerization method in which the body is contacted in a vapor or vaporized state, but it can be selected according to the purpose.

  Although it does not specifically limit as a dose irradiated with ionizing radiation, 5-250 kGy is preferable, 10-230 kGy is more preferable, 20-200 kGy is further more preferable. If the dose is less than 5 kGy, the dose is too small and the graft ratio may be lowered, and the target metalloid ion adsorption amount may not be obtained. In the case of 250 kGy or more, there are concerns that the processing step is costly and the resin deteriorates during irradiation.

  Although the temperature at the time of irradiating ionizing radiation is not specifically limited, Less than 60 degreeC is preferable and 0 to 50 degreeC is more preferable. When the temperature is 60 ° C. or higher, active species generated by ionizing radiation are deactivated, and the subsequent reactivity may be reduced. If it is less than 0 ° C., special cooling measures are required, which may be costly.

  As a method for introducing a graft chain having an N-methylglucamine group, N-methylglucamine is grafted after an unsaturated monomer having a reactive group is grafted to N-methylglucamine using ionizing radiation. A method of converting to a camin group is preferably used.

  The unsaturated monomer to be graft-polymerized may be any monomer having a reactive group that can be converted to an N-methylglucamine group after polymerization, for example, an unsaturated group having an epoxy group such as glycidyl (meth) acrylate. Monomers, unsaturated monomers having a halogenated alkyl group such as chloromethylstyrene, chloroethyl (meth) acrylate, and chloro-2-hydroxypropyl (meth) acrylate are used.

  The reaction conditions such as the concentration of the unsaturated monomer to be contacted and the polymerization treatment time can be appropriately set by the party depending on the required graft ratio and the like. Further, the unsaturated monomer may be polymerized in a state dissolved in a solvent, or the unsaturated monomer may be polymerized by emulsifying the unsaturated monomer in water or the like using a surfactant. The temperature during the polymerization is preferably 40 ° C to 150 ° C. If the temperature is too low, the reaction is difficult to proceed. If the temperature is too high, the reaction may be difficult to control.

  In the case of conversion to an N-methylglucamine group, the unsaturated monomer is graft-polymerized to an ethylene-vinyl alcohol copolymer as a base component, and then the graft copolymer and N-methylglucamine are converted. It can be introduced by reacting with camin or a salt thereof.

  The amount (graft ratio) of the unsaturated monomer introduced by graft polymerization is not particularly limited, but is 30 to 900 parts by mass (30 to 900%) with respect to 100 parts by mass of the ethylene-vinyl alcohol polymer. Is preferable, 100 to 800 parts by mass (100 to 800%) is more preferable, 200 to 700 parts by weight (200 to 700%) is further preferable, and 300 to 700 parts by weight (300 to 700%) is preferable. It is particularly preferred that When the graft ratio is less than 30 parts by mass, the adsorption performance is often insufficient. When the graft ratio exceeds 900 parts by mass, synthesis is generally difficult.

  The solvent used for the introduction of the N-methylglucamine group is not particularly limited as long as N-methylglucamine can be dissolved. Water or methanol is used, but water is particularly used because of its high solubility.

  The reaction temperature at the time of introducing the N-methylglucamine group and the concentration of the N-methylglucamine solution are not particularly limited and are appropriately selected. For example, the temperature at the time of introduction can be appropriately selected from the range of 20 ° C to 100 ° C. If the temperature is too low, the reaction is difficult to proceed. If the temperature is too high, the reaction may be difficult to control.

  The form of the ethylene-vinyl alcohol polymer used for the graft polymerization is not particularly limited because it can be selected according to the shape of the desired graft copolymer, but it may be in the form of particles in consideration of the use of an adsorbent. preferable. In the case of particles, particles having a target particle size can be used by appropriate pulverization or the like, but the particle size is preferably 55 μm to 3000 μm, more preferably 60 μm to 2500 μm, and most preferably 65 μm to 2000 μm. When the particle size is too small, handling is difficult, for example, the fine powder tends to fly. If the particle diameter is too large, the graft ratio may not increase and the target metalloid ion adsorption ability may not be sufficiently obtained.

  Further, from the viewpoint of efficiently introducing the graft chain, it is preferable to use a porous ethylene-vinyl alcohol copolymer that is made porous for introducing the graft chain.

The ethylene-vinyl alcohol copolymer may be made porous by melt-mixing a pore-forming material such as a foaming agent and the ethylene-vinyl alcohol copolymer, but the viewpoint of controlling the size of the pores From the above, the porous ethylene-vinyl alcohol copolymer is obtained by mixing the ethylene-vinyl alcohol copolymer and the water-soluble polymer by melt kneading to obtain a composite in which the melt is cooled and solidified, and It is preferably formed by a step of extracting a water-soluble polymer from the complex.
In the present invention, “cooling and solidifying a melt” means cooling and solidifying the melt without using a solidification bath or the like.

  The water-soluble polymer used in the present invention is not particularly limited as long as it can be melt-mixed with the ethylene-vinyl alcohol copolymer, and generally known water-soluble polymers can be used. Examples of the water-soluble polymer include starch; gelatin; cellulose derivatives; water-soluble amine-based polymers such as polyvinylamine and polyallylamine; polyacrylic acid; polyacrylamide such as polyisopropylacrylamide; polyvinylpyrrolidone; Among these, polyvinyl alcohol is particularly preferably used because it is excellent in melt kneading with an ethylene-vinyl alcohol copolymer and easy to control the voids.

  The ratio of the ethylene-vinyl alcohol copolymer and the water-soluble polymer can be appropriately determined according to the required degree of porosity. For example, the ethylene-vinyl alcohol copolymer: water-soluble polymer is 100: 0 to about 20:80, preferably about 100: 0 to 30:70.

  The polyvinyl alcohol used in the present invention can have a structural unit other than the structural unit derived from the vinyl alcohol unit and the vinyl ester monomer as long as the effects of the present invention are obtained. The structural unit includes, for example, α-olefins such as ethylene, propylene, n-butene, isobutylene and 1-hexene; acrylic acid and salts thereof; methyl acrylate, ethyl acrylate, N-propyl acrylate, acrylic acid i Unsaturated monomers having an acrylate group such as propyl, N-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate and octadecyl acrylate; methacrylic acid And salts thereof; methyl methacrylate, ethyl methacrylate, N-propyl methacrylate, i-propyl methacrylate, N-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid Dodecyl, octadecyl methacrylate, etc. Unsaturated monomer having a methacrylic acid ester group; acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and its salt, acrylamidopropyldimethylamine and its salt (For example, quaternary salts); methacrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, methacrylamide propane sulfonic acid and its salts, methacrylamide propyldimethylamine and its salts (for example, quaternary salts); methyl vinyl ether, ethyl Vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether Vinyl ethers such as ether, stearyl vinyl ether and 2,3-diacetoxy-1-vinyloxypropane; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene chloride, fluorine Vinylidene halides such as vinylidene chloride; allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, and salts or esters thereof A vinylsilyl compound such as vinyltrimethoxysilane and isopropenyl acetate. The content of the structural unit is less than 10 mol%.

  The viscosity average polymerization degree (measured in accordance with JIS K6726) of the polyvinyl alcohol used in the present invention is not particularly limited, but is preferably 100 to 10,000, more preferably 200 to 7,000, still more preferably. Is 300 to 5,000. If the viscosity average degree of polymerization deviates from the above range, the surface area of the resulting porous body may be reduced.

  The saponification degree of the polyvinyl alcohol used in the present invention is not particularly limited, but is preferably 50 mol% or more, more preferably 60 to 98 mol%, and particularly preferably 70 to 95 mol%. When the saponification degree is less than 50 mol%, the water solubility is lowered, and the extractability in hot water extraction after molding is deteriorated. Polyvinyl alcohol having a saponification degree higher than 98 mol% is difficult to melt and mix.

  When the ethylene-vinyl alcohol copolymer of the present invention is made porous, for example, a composite in which an ethylene-vinyl alcohol copolymer and a water-soluble polymer are mixed by melt kneading and the melt is cooled and solidified ( After obtaining a compound, it is obtained by extracting a water-soluble polymer from this complex. The method of melt kneading is not particularly limited, and a known kneader such as a single screw extruder, a twin screw extruder, a Brabender, or a kneader can be used. In order to obtain a target shape, pulverization or the like may be performed at each stage as necessary.

  Moreover, as long as the water-soluble polymer can be extracted without dissolving the ethylene-vinyl alcohol copolymer, the solvent used for the extraction is not particularly limited, and water, various organic solvents, and a mixture of water and an organic solvent. However, from the viewpoint of utilizing a water-soluble polymer, it is preferable to use water, particularly hot water, as the solvent. The temperature of hot water is preferably 40 ° C to 120 ° C, more preferably 50 ° C to 100 ° C.

The porous ethylene-vinyl alcohol polymer thus obtained is a porous body, but it is sufficient that pores are formed at least on the surface, and it is necessary that the pores are formed to the inside. Absent. In this case, the porous body has a structure containing at least 10, preferably 100 or more, more preferably 1,000 or more pores having a major axis of 0.01 μm to 20 μm per 1 cm ^{2 of} area. Have The pores formed on the surface may have an average length of about 0.01 μm to 20 μm, preferably 0.05 μm to 10 μm, more preferably about 0.2 μm to 5 μm. The average value of the major axis of these pores is a value measured by the method described in the examples described later.

  The graft copolymer of the present invention may contain additives such as a crosslinking agent, inorganic fine particles, a light stabilizer, and an antioxidant as long as the effects of the present invention are not impaired.

(Semi-metal adsorbent)
The third configuration of the present invention is a metalloid adsorbent using an ethylene-vinyl alcohol-based graft copolymer into which a graft chain having an N-methylglucamine group is introduced.
Since this graft copolymer has excellent metalloid adsorption ability, it is particularly preferable to use it as a metalloid adsorbent.

(Adsorbent shape)
The shape of the adsorbent of the present invention is not particularly limited, depending on the application location, from various shapes such as fibers and aggregates of woven and knitted fabrics and nonwoven fabrics, particles, sheets, hollow fibers, and films or processed products thereof. You can choose. Among these, it is preferable to be particulate from the viewpoint of improving the adsorptivity with metal ions and being easily packed in a closed space such as a column. When it is particulate, the adsorbent may be spherical or non-spherical (for example, irregularly shaped particles).

(Semimetal recovery method)
The metalloid adsorbent of the present invention can recover various metalloids with high efficiency and low cost by a simple operation. The metalloid recovery method includes, for example, an adsorption step of bringing the metalloid adsorbent of the present invention into contact with a metalloid ion-containing liquid containing the target metalloid and adsorbing the metalloid on the adsorbent. May be. The adsorbent adsorbing the metalloid may recover the metalloid by an elution operation or combustion.

  Although it does not specifically limit as a collection object of the metalloid adsorbent of this invention, Boron, arsenic, germanium, selenium, antimony, etc. are mentioned.

  Taking advantage of the above-described metalloid adsorption performance, the metalloid adsorbent of the present invention can be used, for example, to remove harmful substances contained in factory wastewater, mine wastewater, hot spring water, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by these Examples.

[Calculation of average pore length]
The dry particle surface was observed using a scanning electron microscope. Arbitrary 50 pores were selected from the pores formed on the surface, and the major axis of each pore was measured. The 50 major axes were averaged to derive an average value. However, in the case of 1 nm or less, since it cannot be distinguished from scratches, deposits, etc., it was excluded from the selection. The dried particles were prepared by drying at 100 ° C. for 3 hours with a hot air dryer.

[Graft ratio]
Calculation was performed according to the following formula.
Graft rate [w / w (%)] = 100 × (mass of graft chain imparted) / (mass of substrate)

[Amount of functional group]
Let W be the mass change before and after performing the reaction for introducing N-methylglucamine. Calculation was performed according to the following formula.
Functional group amount [mmol / g] = (W [g] / reaction substrate molecular weight [g / mol]) / (resin particle weight after reaction [g]) × 1000

[Boron adsorption]
A commercially available 1000 mg / L boron standard solution for atomic absorption was diluted to 100 mg / L, and 100 mg of a semimetal ion adsorbent was added to 40 mL of an adsorbed solution adjusted to pH = 8 by adding sodium hydroxide. Stir for 24 hours at ° C. Thereafter, the boron concentration measured with an ICP emission analyzer (manufactured by Nippon Jarrel Ash, IRIS-AP) is defined as C (mg / L). The boron adsorption amount is obtained from the following equation.
Boron adsorption amount per 1 g of graft copolymer (mg / g) = 40−0.4 × C (mg / L)

[Arsenic adsorption]
A commercially available 1000 mg / L arsenic standard solution for atomic absorption is diluted to 20 mg / L, and 50 mg of a semi-metal ion adsorbent is added to 100 mL of an adsorbed solution adjusted to pH = 3 by adding nitric acid. And stir for 24 hours. Thereafter, the arsenic concentration measured with an atomic absorption photometer (manufactured by Hitachi, Ltd., Z-5000) is defined as D (mg / L). The amount of arsenic adsorption is obtained from the following equation.
Arsenic adsorption amount per 1 g of graft copolymer (mg / g) = 40-2D (mg / L)

[Example 1]
90 parts by mass of a commercially available ethylene-vinyl alcohol copolymer (Kuraray Co., Ltd., “F101”, MFR 3.8 g / 10 min) and 10 parts by mass of a vinyl alcohol polymer (Kuraray Co., Ltd., “PVA205”) After melt-kneading in a lab plast mill, the compound obtained by cooling and solidifying the melt was pulverized, and particles having a particle diameter of 1180 to 1400 μm were produced using a sieve. Furthermore, the obtained particle | grains were processed in hot water, the vinyl alcohol-type polymer was extracted, and the porous ethylene-vinyl alcohol-type copolymer particle was obtained. The average pore long diameter of the porous particles was 0.36 μm. The porous particles were irradiated with 60 kGy ionizing radiation, allowed to stand in air at 25 ° C. for 1 hour, and then immersed and stirred in an isopropanol solution of glycidyl methacrylate substituted with nitrogen at 80 ° C. for graft polymerization. When the graft ratio of the obtained particles was evaluated, it was 407%. Further, the particles are immersed and stirred in an aqueous solution of N-methylglucamine under the condition of 80 ° C., an addition reaction of N-methylglucamine is performed, and an ethylene-vinyl alcohol-based graft grafted with the target N-methylglucamine group is obtained. A copolymer was obtained. When the amount of N-methylglucamine group introduced was evaluated, it was 2.6 mmol / g. The obtained ethylene-vinyl alcohol-based graft copolymer was classified into particles having a particle diameter of 2360 μm to 2800 μm using a sieve, and the amount of boron adsorbed was evaluated. The particle composition is shown in Table 1, and the adsorption results are shown in Table 2.

[Example 2]
A commercially available ethylene-vinyl alcohol copolymer (“E105” manufactured by Kuraray Co., Ltd., MFR 13 g / 10 min) was pulverized, and particles having a particle size of 212 μm to 425 μm were prepared using a sieve. The particles were irradiated with ionizing radiation of 30 kGy, allowed to stand in air at 25 ° C. for 1 hour, and then immersed and stirred in an isopropanol solution of glycidyl methacrylate substituted with nitrogen at 80 ° C. for graft polymerization. When the graft ratio of the obtained particles was evaluated, it was 128%. Further, the particles are immersed and stirred in an aqueous solution of N-methylglucamine under the condition of 80 ° C., an addition reaction of N-methylglucamine is carried out, and an ethylene-vinyl alcohol-based graft grafted with the target N-methylglucamine group A copolymer was obtained. When the amount of N-methylglucamine group introduced was evaluated, it was 1.6 mmol / g. The obtained ethylene-vinyl alcohol-based graft copolymer was classified into particles having a particle diameter of 212 μm to 500 μm using a sieve, and the amount of boron adsorbed was evaluated. The particle composition is shown in Table 1, and the adsorption results are shown in Table 2.

[Example 3]
Laboplast mills 90 parts by mass of commercially available ethylene-vinyl alcohol copolymer (Kuraray Co., Ltd., “G156”, MFR 15 g / 10 min) and 10 parts by mass of vinyl alcohol polymer (Kuraray Co., Ltd., PVA217). After melt-kneading, the compound obtained by cooling and solidifying the melt was pulverized, and particles having a particle diameter of 212 μm to 425 μm were produced using a sieve. Further, the obtained particles were treated in hot water to extract a vinyl alcohol polymer, and porous ethylene-vinyl alcohol copolymer particles were obtained. The average pore long diameter of the porous particles was 0.95 μm. The porous particles were irradiated with ionizing radiation of 100 kGy, allowed to stand in air at 25 ° C. for 1 hour, and then immersed and stirred in an isopropanol solution of glycidyl methacrylate substituted with nitrogen at 80 ° C. for graft polymerization. When the graft ratio of the obtained particles was evaluated, it was 370%. Further, the particles are immersed and stirred in an aqueous solution of N-methylglucamine under the condition of 80 ° C., an addition reaction of N-methylglucamine is performed, and an ethylene-vinyl alcohol-based graft grafted with the target N-methylglucamine group is obtained. A copolymer was obtained. When the amount of N-methylglucamine group introduced was evaluated, it was 2.3 mmol / g. The obtained ethylene-vinyl alcohol-based graft copolymer was classified into particles having a particle diameter of 212 μm to 500 μm using a sieve, and the amount of boron adsorbed was evaluated. The particle composition is shown in Table 1, and the adsorption results are shown in Table 2.

[Example 4]
90 parts by mass of a commercially available ethylene-vinyl alcohol copolymer (Kuraray Co., Ltd., “F101”, MFR 3.8 g / 10 min) and 10 parts by mass of a vinyl alcohol polymer (Kuraray Co., Ltd., “PVA205”) After melt-kneading in a lab plast mill, the compound obtained by cooling and solidifying the melt was pulverized, and particles having a particle size of 106 μm to 212 μm were prepared using a sieve. Furthermore, the vinyl alcohol polymer was extracted from the obtained particles in hot water to obtain porous ethylene-vinyl alcohol copolymer particles. The average pore long diameter of the porous particles was 0.27 μm. The porous particles were irradiated with ionizing radiation of 100 kGy, allowed to stand in air at 25 ° C. for 1 hour, and then immersed and stirred in an isopropanol solution of glycidyl methacrylate substituted with nitrogen at 80 ° C. for graft polymerization. When the graft ratio of the obtained particles was evaluated, it was 371%. Further, the particles are immersed and stirred in an aqueous solution of N-methylglucamine under the condition of 80 ° C., an addition reaction of N-methylglucamine is performed, and an ethylene-vinyl alcohol-based graft grafted with the target N-methylglucamine group is obtained. A copolymer was obtained. When the amount of N-methylglucamine group introduced was evaluated, it was 2.4 mmol / g. The obtained ethylene-vinyl alcohol-based graft copolymer was classified into particles having a particle diameter of 212 μm to 500 μm using a sieve, and the amount of boron adsorbed was evaluated. The particle composition is shown in Table 1, and the adsorption results are shown in Table 2.

[Example 5]
80 parts by mass of a commercially available ethylene-vinyl alcohol copolymer (Kuraray Co., Ltd., “L104”, MFR 8.9 g / 10 min) and 20 parts by mass of a vinyl alcohol polymer (Kuraray Co., Ltd., “PVA205”) After melt-kneading in a lab plast mill, the compound obtained by cooling and solidifying the melt was pulverized, and particles having a particle diameter of 300 μm to 500 μm were prepared using a sieve. Furthermore, the vinyl alcohol polymer was extracted from the obtained particles in hot water to obtain porous ethylene-vinyl alcohol copolymer particles. The average value of the major axis of the pores of the porous particles was 0.41 μm. The porous particles were irradiated with 20 kGy ionizing radiation, allowed to stand in air at 25 ° C. for 1 hour, and then immersed and stirred in an isopropanol solution of glycidyl methacrylate substituted with nitrogen at 80 ° C. for graft polymerization. When the graft ratio of the obtained particles was evaluated, it was 269%. Further, the particles are immersed and stirred in an aqueous solution of N-methylglucamine under the condition of 80 ° C., an addition reaction of N-methylglucamine is performed, and an ethylene-vinyl alcohol-based graft grafted with the target N-methylglucamine group is obtained. A copolymer was obtained. When the amount of N-methylglucamine group introduced was evaluated, it was 2.1 mmol / g. The obtained ethylene-vinyl alcohol-based graft copolymer was classified into particles having a particle diameter of 212 μm to 500 μm using a sieve, and the amount of boron adsorbed was evaluated. The particle composition is shown in Table 1, and the adsorption results are shown in Table 2.

[Example 6]
A commercially available ethylene-vinyl alcohol copolymer (Kuraray Co., Ltd., “G156”, MFR 15 g / 10 min) was pulverized, and particles having a particle diameter of 300 μm to 500 μm were prepared using a sieve. The particles were irradiated with 20 kGy ionizing radiation, allowed to stand in air at 25 ° C. for 1 hour, and then immersed and stirred in an isopropanol solution of glycidyl methacrylate substituted with nitrogen at 80 ° C. for graft polymerization. When the graft ratio of the obtained particles was evaluated, it was 85%. Further, the particles are immersed and stirred in an aqueous solution of N-methylglucamine under the condition of 80 ° C., an addition reaction of N-methylglucamine is carried out, and an ethylene-vinyl alcohol-based graft grafted with the target N-methylglucamine group A copolymer was obtained. When the amount of N-methylglucamine group introduced was evaluated, it was 1.3 mmol / g. The obtained ethylene-vinyl alcohol-based graft copolymer was classified into particles having a particle diameter of 425 μm to 710 μm using a sieve, and the amount of boron adsorbed was evaluated. The particle composition is shown in Table 1, and the adsorption results are shown in Table 2.

[Comparative Example 1]
Commercially available polyethylene (manufactured by Prime Polymer Co., Ltd., “7000F”) was pulverized, and particles having a particle size of 212 μm to 425 μm were prepared using a sieve. The particles were irradiated with 200 kGy ionizing radiation, left in air at 25 ° C. for 1 hour, and then immersed in an isopropanol solution of glycidyl methacrylate substituted with nitrogen at 80 ° C. for graft polymerization. When the graft ratio of the obtained particles was evaluated, it was 5%. Further, the particles are immersed and stirred in an aqueous solution of N-methylglucamine under the condition of 80 ° C., an addition reaction of N-methylglucamine is carried out, and the target N-methylglucamine group grafted polyethylene-based graft copolymer Got. When the amount of N-methylglucamine group introduced was evaluated, it was 0.2 mmol / g. The obtained polyethylene-based graft copolymer was classified into particles having a particle diameter of 425 μm to 710 μm using a sieve, and the amount of boron adsorbed was evaluated. The particle composition is shown in Table 1, and the adsorption results are shown in Table 2.

[Comparative Example 2]
Commercially available crystalline cellulose particles (manufactured by Asahi Kasei Chemicals Corporation, “Selfia CP-203”) are classified into particles having a particle diameter of 212 μm to 300 μm using a sieve, immersed in ion-exchanged water for 12 hours, and then spin-dehydrated. . The particles were irradiated with 20 kGy ionizing radiation, allowed to stand in air at 25 ° C. for 1 hour, and then immersed and stirred in an isopropanol solution of glycidyl methacrylate substituted with nitrogen at 80 ° C. for graft polymerization. When the graft ratio of the obtained particles was evaluated, it was 9%. Further, the cellulose-based graft copolymer in which the target N-methylglucamine group is grafted by immersing and stirring the particles in an N-methylglucamine aqueous solution at 80 ° C. to perform addition reaction of N-methylglucamine. Got. When the amount of N-methylglucamine group introduced was evaluated, it was 0.6 mmol / g. The obtained cellulose-based graft copolymer was classified into particles having a particle diameter of 212 μm to 500 μm using a sieve, and the amount of boron adsorbed was evaluated. The particle composition is shown in Table 1, and the adsorption results are shown in Table 2.

  As shown in Examples 1 to 5, when graft polymerization by ionizing radiation was carried out using an ethylene-vinyl alcohol copolymer, the graft polymerization proceeded relatively stably even when left at room temperature after irradiation with ionizing radiation. Thus, an ethylene-vinyl alcohol graft copolymer having an N-methylglucamine group introduced into the graft chain could be obtained. Further, the obtained ethylene-vinyl alcohol-based graft copolymer showed adsorptivity of semimetals such as boron and arsenic.

  As in Comparative Examples 1 and 2, when polyethylene or cellulose commonly used in graft polymerization using ionizing radiation is used, there is a problem that graft polymerization does not proceed much if left at room temperature after irradiation with ionizing radiation. Therefore, it has been found that there is a possibility that the process management may become complicated. The obtained graft copolymer also had low metalloid adsorption.

  ADVANTAGE OF THE INVENTION According to this invention, the ethylene-vinyl alcohol type graft copolymer by which N-methylglucamine group was introduce | transduced into the graft chain, and its manufacturing method can be provided. Moreover, for example, semimetals such as boron and arsenic can be efficiently recovered using the obtained ethylene-vinyl alcohol-based graft copolymer.

  As described above, the preferred embodiments of the present invention have been described. However, various additions, modifications, or deletions are possible without departing from the spirit of the present invention, and such modifications are also included in the scope of the present invention. It is.

Claims (12)

A base material component composed of an ethylene-vinyl alcohol copolymer;
An ethylene-vinyl alcohol-based graft copolymer composed of a graft chain having an N-methylglucamine group introduced to the base material component.   The graft copolymer according to claim 1, wherein the amount of N-methylglucamine group introduced is 0.7 mmol / g or more.   An ethylene-vinyl alcohol-based graft copolymer, wherein the graft copolymer according to claim 1 or 2 is a porous body.   The graft copolymer of Claim 3 WHEREIN: The ethylene-vinyl alcohol type graft copolymer particle whose major axis of the pore formed in the surface of a porous body is 0.01 micrometer-20 micrometers.   The graft copolymer as described in any one of Claims 1-4 WHEREIN: The ethylene-vinyl alcohol-type graft copolymer which is a particulate form with a particle diameter of 30 micrometers-5000 micrometers.   A step of preparing an ethylene-vinyl alcohol copolymer (step A), and introducing a graft chain having a methyl glucamine group into the ethylene-vinyl alcohol copolymer, the methyl glucamine group is introduced. And a step (Step B) for obtaining a graft copolymer into which the graft chain is introduced. A method for producing an ethylene-vinyl alcohol-based graft copolymer.   The method for producing a graft copolymer according to claim 6, wherein the ethylene-vinyl alcohol copolymer prepared in step A is a porous body.   8. The manufacturing method according to claim 7, wherein the step A includes melting and mixing the ethylene-vinyl alcohol copolymer and the water-soluble polymer, and cooling and solidifying the mixed melt, whereby the ethylene-vinyl alcohol copolymer. A method for producing a graft copolymer, comprising: obtaining a composite comprising a polymer and a water-soluble polymer; and extracting the water-soluble polymer from the composite to obtain a porous body.   The method for producing a graft copolymer according to any one of claims 6 to 8, wherein a graft chain is introduced using ionizing radiation in Step B.   The process for producing a graft copolymer, wherein, in Step B of the production method according to claim 9, after irradiation with ionizing radiation, the irradiated product can be left in air at room temperature for a predetermined time.   The manufacturing method of the graft copolymer as described in any one of Claims 8-10 whose water-soluble polymer is polyvinyl alcohol.   The metalloid adsorbent which uses the graft copolymer as described in any one of Claims 1-5.