JP6440502B2 - Metal ion scavenger - Google Patents

Description

  The present invention relates to a hydrogel having a network structure in which an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and maleic acid is crosslinked.

  Examples of water gels that are currently known to form hydrogels include water-soluble polymers such as starch, carrageenan, fiber derivatives, gelatin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, and polyoxyethylene oxide. There is. Hydrogels using these water-soluble polymers are widely used in applications such as a fragrance material, a fireproof material, a heat insulation material, and a cold insulation material.

  However, hydrogels using these water-soluble polymers are generally complicated in their production methods. For example, stepwise temperature adjustment or the like is necessary (Patent Document 1 etc.), gelation reaction under high temperature is necessary, or a stable hydrogel cannot be formed unless the temperature is 0 ° C. or lower, Alternatively, a production method in which the gelation reaction needs to be promoted by strictly adjusting the pH of the aqueous solution (Patent Document 2, etc.) is mainstream, and there are few production methods for hydrogel that can be easily gelled. In addition, when the water content of the hydrogel is high, many gelation reactions are slow. Furthermore, the hydrogel obtained by the conventional method has a high swelling rate due to moisture absorption, and when used in a certain container, when the moisture is released from the moisture absorption state, the volume shrinks, resulting in a void in the container. There's a problem.

  On the other hand, from the viewpoint of environmental purification and environmental protection in recent years, there is a fact that the separation, removal, and recovery of metal ions that cause various industrial problems are very important.

JP2013-234280A Special table 2009-536940

  The present invention has been made in view of the above-mentioned problems, and its main purpose is to provide a hydrogel that has a relatively simple manufacturing method, a small volume expansion coefficient at the time of water absorption, and a high metal ion scavenging property. is there.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by a hydrogel having the following constitution, and have further completed the present invention by further study based on this finding.

  That is, the hydrogel according to one aspect of the present invention has a network structure in which an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and maleic acid is crosslinked, and absorbs 200 parts by weight of water. The volume expansion coefficient is 120% or less.

  With such a configuration, it is possible to provide a hydrogel having a small volume expansion coefficient at the time of water absorption and high metal ion scavenging properties. Further, the hydrogel of the present invention has an advantage that it can be obtained by a relatively simple production method.

  Furthermore, in the hydrogel, the network structure is preferably obtained by crosslinking an α-olefin-maleic acid copolymer with a polyvalent amine represented by the following formula.

(In the formula, n represents an integer of 1 to 50)
Thereby, the above effect can be obtained more reliably.

  Furthermore, it is preferable that the hydrogel does not contain ammonia-derived ammonium in the molecule. Thereby, a hydrogel with higher metal ion scavenging property can be provided.

  In addition, a metal ion scavenger according to another aspect of the present invention is characterized by comprising the hydrogel described above.

  ADVANTAGE OF THE INVENTION According to this invention, the volume expansion coefficient at the time of water absorption is small, and a hydrogel with a high metal ion trapping property is provided. The hydrogel of the present invention can be obtained by a relatively simple production method.

  Hereinafter, although embodiment of this invention is described in detail, this invention is not limited to these.

  The hydrogel of this embodiment has a network structure in which an α-olefin-maleic acid copolymer obtained by copolymerization of an α-olefin and maleic acid is crosslinked, and has a volume expansion coefficient of 120% or less. And

  By having such a configuration, it is possible to provide a hydrogel that is relatively simple to manufacture, can maintain the particle shape during water absorption, has a small volume expansion coefficient, and has high metal ion scavenging properties. Conceivable.

  In the present embodiment, the hydrogel refers to a structure in which a solvent containing water as a main component is taken in and held in a network structure formed by crosslinking a polymer. The amount of the solvent contained in the hydrogel of the present embodiment is not particularly limited. The solvent taken into the network structure may contain a solvent that dissolves in water or a solvent that is miscible with water to the extent that the effects of the present invention are not affected. The network structure means a structure like a network stretched in three dimensions by crosslinking an α-olefin-maleic acid copolymer obtained by copolymerizing α-olefins and maleic acids. To do.

  The α-olefin used in the present embodiment is a linear or branched olefin having a carbon-carbon unsaturated double bond at the α-position. In particular, olefins having 2 to 12 carbon atoms, particularly 2 to 8 carbon atoms are preferred. Representative examples that may be used include ethylene, propylene, n-butylene, isobutylene, n-pentene, isoprene, 2-methyl-1-butene, 3-methyl-1-butene, n-hexene, 2-methyl- 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-butene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethylbutadiene, 2,5 -Pentadiene, 1,4-hexadiene, 2,2,4-trimethyl-1-pentene and the like. Among these, isobutylene is particularly preferable from the viewpoints of availability, polysynthesis, and product stability. Here, the isobutylene includes a mixture containing isobutylene as a main component, for example, a BB fraction (C4 fraction). These olefins may be used alone or in combination of two or more.

  These olefin monomers may be used alone or in combination of two or more. Among these monomers, α-olefins, particularly α-olefins such as ethylene and isobutylene are preferably used. In particular, use of isobutylene is more preferable from the viewpoint of exhibiting an action of suppressing swelling of the polymer due to moisture absorption.

  Examples of maleic acids used in this embodiment include maleic anhydride, maleic acid, maleic acid monoesters (for example, methyl maleate, ethyl maleate, propyl maleate, phenyl maleate, etc.), maleic acid diesters (for example, Maleic anhydride derivatives such as dimethyl maleate, diethyl maleate, dipropyl maleate, diphenyl maleate, etc.), maleic imide or N-substituted derivatives thereof (eg maleic imide, N-methyl maleimide, N-ethyl maleimide, N-substituted alkylmaleimides such as N-propylmaleimide, Nn-butylmaleimide, Nt-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-methylphenylmaleimide, N-ethylphenylmaleimide, etc. N-substitution of Rualkylphenyl maleimide or N-substituted alkoxyphenyl maleimide such as N-methoxyphenyl maleimide and N-ethoxyphenyl maleimide), and further halides thereof (for example, N-chlorophenyl maleimide), citraconic anhydride Citraconic acid, citraconic acid monoester (eg, methyl citraconic acid, ethyl citraconic acid, propyl citraconic acid, phenyl citraconic acid, etc.), citraconic acid diester (eg, dimethyl citraconic acid, diethyl citraconic acid, dipropyl citraconic acid, diphenyl citraconic acid) Citraconic anhydride derivatives, citraconic imides or N-substituted derivatives thereof (for example, citraconic imide, 2-methyl-N-methylmaleimide, 2-methyl-N-ethylmaleimide, 2-methyl) N-substituted alkylmaleimide 2-methyl-N-phenyl such as N-propylmaleimide, 2-methyl-Nn-butylmaleimide, 2-methyl-Nt-butylmaleimide, 2-methyl-N-cyclohexylmaleimide 2-methyl-N-substituted alkylphenylmaleimide such as maleimide, 2-methyl-N-methylphenylmaleimide, 2-methyl-N-ethylphenylmaleimide, or 2-methyl-N-methoxyphenylmaleimide, 2 Preferred examples include 2-methyl-N-substituted alkoxyphenylmaleimides such as -methyl-N-ethoxyphenylmaleimide) and further halides thereof (for example, 2-methyl-N-chlorophenylmaleimide). Among these, use of maleic anhydride is preferable from the viewpoint of availability, polymerization rate, and ease of molecular weight adjustment. These maleic acids may be used alone or in combination.

  In this embodiment, when maleic anhydride, which is preferably used as maleic acid, is used, the copolymer can impart water solubility by hydrolysis of the maleic anhydride site, if necessary. In performing the hydrolysis, ammonia, lithium hydroxide, sodium hydroxide, potassium hydroxide, or the like can be used. These may be used singly or in combination. Ammonia is preferably used for various purposes, particularly for the purpose of capturing metal ions.

  Various methods can be employed for the reaction between the copolymer using maleic anhydride and ammonia, but a method in which ammonia gas is brought into contact with the solid powder of the copolymer, and the copolymer powder is slurried in a solvent. A method in which ammonia gas is contacted while being bubbled in a solvent or a method in which copolymer powder is dissolved in aqueous ammonia is preferably employed. The reaction ratio of the copolymer of this embodiment and ammonia is about 0.5-2 mol of ammonia with respect to 1 mol of maleic anhydride groups contained in the copolymer, and more preferably 1-2 mol.

  The composition ratio of α-olefins and maleic acids in the copolymer of the present embodiment is a carboxylate salt derived from maleic acids obtained by reacting and neutralizing the produced copolymer with a basic substance. As long as the composition containing the copolymer is soluble in water, it may be of any degree as long as the effects of the present invention are not impaired. Usually, it is about 1-10 moles of α-olefins per mole of maleic acids. In particular, in the case of each copolymer of ethylene or isobutylene and maleic anhydride preferably used in this embodiment, the amount is about 1 to 3 moles of ethylene and isobutylene per mole of maleic anhydride. Preferably, it is an alternating copolymer of about the same mole.

  The molecular weight of the copolymer is such that the intrinsic viscosity measured at 30 ° C. in a dimethylformamide solution is 0.05 to 5 (dl / g), preferably about 0.1 to 3 (dl / g). It is desirable that

  The hydrogel of this embodiment is a copolymer of an α-olefin and maleic acid as described above, represented by the following general formula:

(In the formula, n represents an integer of 1 to 50)
A hydrogel obtained by a crosslinking reaction treatment with a polyvalent amine represented by

  More preferably, it is a hydrogel obtained by subjecting a reaction product obtained by reacting a copolymer of an α-olefin and maleic acid to a base to a crosslinking reaction with the polyvalent amine.

  Moreover, the said polyvalent amine used in this embodiment has a role as a gelatinizer. Specific examples of the polyvalent amine used in the present embodiment include ethylenediamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, linear polyethyleneimine, branched polyethyleneimine, and the like. Those having a large number of n in the above formula can also be used. However, a gel having a number of n exceeding 50 has a very high gelation speed, and a gel may be partially formed, so that a uniform hydrogel cannot be formed. Even if ammonia or a monovalent amine is used as the gelling agent, the intended product in the present invention cannot be obtained.

  In the present invention, the polyamine may be added in any amount as long as the resulting hydrogel can sufficiently retain water and supplement the metal, and is usually an isobutylene-maleic anhydride alternating copolymer 100. It is used in the range of 0.5 to 5.5 parts by weight, more preferably 0.6 to 5 parts by weight with respect to parts by weight. If too much polyvalent amine is used for cross-linking, there is a problem that the liquid holding ability is lowered and the adsorptivity of ions is lowered. If the amount is too small, the adsorbing power of metal ions is lowered although the liquid is held, which is not preferable.

  In the present embodiment, the hydrogel obtained by crosslinking a copolymer of a monomer of α-olefins and maleic acids with a polyvalent amine is a mixture of α-olefins and maleic acids in a solvent. A hydrogel obtained by reacting a copolymer obtained by radical polymerization with a polyvalent amine.

  Furthermore, a known stabilizer, an antioxidant such as triphenylphosphine, and the like can be added to the hydrogel of the present embodiment as necessary.

  The hydrogel of this embodiment has a volume expansion coefficient of 120% or less. Specifically, for example, the volume expansion coefficient in the present embodiment refers to the volume expansion coefficient when 200 parts by weight of water is absorbed with respect to 100 weights of the dried hydrogel. When the volume expansion coefficient exceeds 120%, the water is diluted by the water in which the affinity between the carboxylic acid of the hydrogel and the metal is present, and sufficient metal ion scavenging properties cannot be provided. More preferably, the volume expansion coefficient is 115% or less. Although there is no lower limit in particular in the volume expansion coefficient of this embodiment, when filling and using a container, it is desirable that it is 100% or more from a viewpoint that a space | gap will produce | generate when it shrink | contracts and filling efficiency will fall.

  The volume expansion coefficient in the present embodiment can be measured by, for example, filling a graduated cylinder with a dried hydrogel, adding and absorbing water whose volume has been measured separately, and measuring the amount of expansion.

  In the hydrogel of the present embodiment, the volume expansion coefficient can be adjusted, for example, by adjusting the degree of crosslinking depending on the amount of polyvalent amine added.

  In addition, the dried hydrogel refers to the state which does not contain water molecules other than crystal water. The method for obtaining a dried hydrogel is not limited. For example, a method of heating above the boiling point of water under normal pressure, a method of heating while applying an air flow under normal pressure, and a method of distilling off water under reduced pressure. Can be used. From the viewpoint of suppressing structural changes during drying of the hydrogel, it is preferable to use a method of heating while applying an air flow under normal pressure, or a method of distilling off water under reduced pressure.

  Although it does not specifically limit as a manufacturing method of the hydrogel of this embodiment, The example is demonstrated concretely. First, the polyvalent amine described above is added in an amount of 0.5 to 5.5 parts by weight with respect to 100 parts by weight of the copolymer in a 1 to 60% by weight aqueous solution of the reaction product of the copolymer and ammonia. Add and mix to make uniform aqueous solution. Thereafter, for example, the aqueous solution can be poured into a desired mold and gelled at room temperature or under heating.

  The time until gelation varies depending on the type of copolymer, its concentration, the type of gelling agent (polyvalent amine), its concentration and gelation temperature, and they can be appropriately selected as necessary. Generally, it takes about several minutes to a few dozen days. The gelation reaction becomes faster as the gelation temperature increases. According to the present embodiment, the gelation reaction proceeds sufficiently at room temperature even when the aqueous solution of the reaction product of the copolymer and ammonia has a low concentration of about 5 to 10% by weight. A hydrogel can be obtained in a desired time. Similarly, the gel strength of the produced hydrogel can be freely adjusted by selecting the type and concentration of the copolymer and the gelling agent.

  Specifically, for example, when allowed to stand at various temperatures, gelation takes place at 20 ° C. for 6 hours, at 30 ° C. for 3 to 4 hours, at 40 ° C. for 1 to 2 hours, and at 60 ° C. for 10 to 20 minutes.

  Further, in the present embodiment, ammonia remaining in the hydrogel molecule reacts with metal ions when the hydrogel is used as a metal ion scavenger, for example, to increase water solubility and reduce metal ion adsorption. This is not preferable. Accordingly, it is preferable to heat at the time of gelation, and it is desirable to perform gelation in the range of 60 ° C. to 120 ° C., more preferably in the range of 80 ° C. to 100 ° C., to remove ammonia from the reaction system. Alternatively, an inert gas such as nitrogen can be introduced into the reaction solution at the time of gelation to improve the ammonia removability.

  The obtained hydrogel can be dehydrated by a method such as hot air drying or vacuum drying, if necessary, to enhance storage stability.

  The hydrogel of this embodiment can be used for various uses from the outstanding characteristic. For example, it can be used for applications such as a metal ion scavenger, a humectant, and a metal exchanger.

  Especially, since it has excellent metal ion scavenging properties, it can be more effective when used as a metal ion scavenger.

  Examples of metal ions that can be captured by the metal ion scavenger of the present embodiment include alkali metal ions such as Li, Na, K, and Rb, alkaline earth metal ions such as Ca, Mg, and Ba, Fe, Zn, Cu, Examples thereof include transition metal ions such as Ni and Cr.

  The capture agent of this embodiment can be suitably used for capturing, fixing, removing, and collecting these metal ions.

  In the present embodiment, the mechanism by which the scavenger captures metal ions is considered to be neutralization with a carboxylic acid and coordination with a crosslinked polyvalent amine.

  The means for capturing metal ions in the solution using the metal ion scavenger of the present embodiment is not particularly limited, but a metal ion scavenger (hydrogel) is added to the ion solution containing metal ions. Metal ions in the solution can be captured by swelling, mixing and stirring. After capture, metal ions contained in the hydrogel can be separated by adding a known technique, for example, by adding acidic water and regenerating the carboxylic acid.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[Manufacture of hydrogel]
Example 1
Isobutylene-maleic anhydride alternating copolymer ([η] = 1.06, Kuraray Co., Ltd. Isoban-10) 100 parts by weight was stirred in a container while ammonia gas was blown into the isobutylene-maleic anhydride alternating copolymer. 117 parts by weight of a reaction product of ammonia and ammonia (hereinafter abbreviated as ammonia adduct) was prepared. Then, 11.7 parts by weight of this ammonia adduct and 90 parts by weight of water were mixed to prepare an aqueous solution. Next, after adding 0.3 parts by weight of tetraethylenepentamine to the obtained aqueous solution and stirring, the solution was allowed to stand at a temperature of 30 ° C. and gelled in 10 hours.

  Furthermore, the obtained gelled product was heated to 90 ° C., and ammonia was removed from the generated vapor out of the system. The obtained hydrogel was dried with hot air at 80 ° C. for 10 hours to obtain 20 g of a dry intermediate (hydrated product). Furthermore, it vacuum-dried at 80 degreeC and 1 Torr for 12 hours, and obtained 10.2 g of dried hydrogels. The dried hydrogel was pulverized to obtain particles having an average particle size of 30 μm. When the volume of 10 g of the particles was measured, the bulk density was 0.58. When 20 g of water was added to this powder, the volume at 25 ° C. was 20.2 ml, and the volume expansion coefficient was 117%.

(Example 2)
The same procedure as in Example 1 was conducted except that 0.5 parts by weight of tetraethylenepentamine was used as the ammonia adduct of the isobutylene-maleic anhydride alternating copolymer used in Example 1. The results of the volume expansion coefficient of the obtained gel are shown in Table 1.

Example 3
The same procedure as in Example 1 was conducted except that 0.5 parts by weight of ethylenediamine was used as the ammonia adduct of the isobutylene-maleic anhydride alternating copolymer used in Example 1. The results of the volume expansion coefficient of the obtained gel are shown in Table 1.

(Comparative Example 1)
The same procedure as in Example 1 was conducted except that 0.01 parts by weight of tetraethylenepentamine was used as the ammonia adduct of the isobutylene-maleic anhydride alternating copolymer used in Example 1. The results of the volume expansion coefficient of the obtained gel are shown in Table 1.

(Comparative Example 2)
While stirring 100 parts by weight of polyacrylic acid having a molecular weight of 170,000 in a container, ammonia gas was blown to prepare 121 parts by weight of a reaction product of polyacrylic acid and ammonia (hereinafter abbreviated as ammonia adduct). Then, 10 parts by weight of this ammonia adduct and 90 parts by weight of water were mixed to prepare an aqueous solution. Next, after adding 0.3 parts by weight of tetraethylenepentamine to the copolymer and stirring the resulting aqueous solution, the solution was allowed to stand at a temperature of 30 ° C., and gelled in 8 hours.

  Furthermore, the obtained gelled product was heated to 90 ° C., and ammonia was removed from the generated vapor out of the system. The obtained gel was dried with hot air at 80 ° C. for 10 hours, dried to 20 g of hydrated material, and further dried under vacuum at 80 ° C. and 1 Torr for 12 hours to obtain 10.2 g of dried gel. This gel was pulverized to obtain particles having an average particle diameter of 42 μm. When the volume of 10 g of the particles was measured, the bulk density was 0.51. When 20 g of water was added to this powder, the volume at 25 ° C. was 45.1 ml, and the volume expansion coefficient was 230%.

[Test Example] Metal ion scavenging evaluation (Test Example 1)
100 mg of aluminum chloride was dissolved in 1000 g of ion exchange water. The hydrogel obtained in Example 1 was swollen with 10 g of ion-exchanged water, added to a 2000 ml beaker containing an aluminum chloride solution, stirred for 3 hours, and the ions in water were analyzed by ICP emission method. Table 2 below shows the aluminum ion concentration before addition and the aluminum ion concentration after addition and stirring.

(Test Example 2)
A metal ion scavenging evaluation test was conducted in the same manner as in Test Example 1 except that a solution in which 100 mg of ferric chloride was dissolved in 1000 g of ion-exchanged water was prepared and the hydrogel obtained in Example 2 was used.

(Test Example 3)
A metal ion scavenging evaluation test was conducted in the same manner as in Test Example 1 except that a solution obtained by dissolving 10 mg of zinc chloride in 1000 g of ion-exchanged water was used and the hydrogel obtained in Example 3 was used.

(Test Example 4)
Except for using the hydrogel prepared in Comparative Example 1, Test Example 1 and the metal ion scavenging evaluation test were performed in the same manner.

(Test Example 5)
Except that the hydrogel prepared in Comparative Example 2 was used, Test Example 1 and the metal ion scavenging evaluation test were performed in the same manner.

From the above results, it was shown that various metal ions can be sufficiently captured by using the hydrogel of the present invention. On the other hand, the hydrogel of the comparative example having a high volume expansion coefficient could not sufficiently capture metal ions.

Claims (2)

a network structure in which an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and maleic acid is crosslinked;
The volume expansion coefficient is 120% or less , and
The network structure is a metal ion scavenger composed of a hydrogel obtained by crosslinking an α-olefin-maleic acid copolymer with a polyvalent amine represented by the following formula.
(In the formula, n represents an integer of 1 to 50) The metal ion scavenger according to claim 1, wherein the hydrogel does not contain ammonia-derived ammonium in the molecule.