JPH0686521B2 - Polyamide and heat resistant metal ion adsorbent - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-resistant metal ion adsorbent composed of a polyamide and a polymer thereof, and more specifically, it is composed of a polyamide having excellent heat resistance and having a chelate-forming ability, and at a high temperature. Also relates to a metal ion adsorbent that can be used stably.

2. Description of the Related Art Selective ion exchange resins, polymer compounds containing chelate ligands, which were born as so-called chelate resins, are used as analytical polymers in functional chemistry that selectively collect specific metal ions from solutions containing metal ions. We are making steady progress in the fields of global environmental chemistry and radiochemistry. In particular, in recent years, water pollution due to heavy metals has become a problem, and there is an increasing interest in chelate resins in the fields of geochemistry and environmental chemistry, such as pollution investigations and removal of industrial waste liquids.

On the other hand, polymer compounds containing metal chelates are heat resistant, flame resistant materials, conductive materials, etc., and fibers and plastics having a coordinating group are made more valuable by coordinating metal ions. Therefore, practical studies are continuing. For example, there is separation and recovery of radionuclides in reactor water of a power generation reactor.

And various metal ion adsorbents are already known, but all are ion-exchange groups such as acidic groups and amino groups,
It consists of a polymer having various chelating groups in the side chain. Therefore, even if the polymer has heat resistance in its main chain, it has a drawback that it is inferior in heat resistance because it has an ion-exchange group or a chelate-forming group in its side chain.

For example, a general-purpose strong acid ion-exchange resin that uses a sulfonic acid group as an ion-exchange group has a gel-type operating temperature of 120 ° C
The mold has a limit of 150 ° C. As long as the styrene-divinylbenzene copolymer is used as the skeleton of the ion exchange resin,
When exposed to high temperatures above ℃, some of the resin softens,
Disassemble.

Therefore, for example, it is proposed to produce a polyphenylene ether having a halomethyl group as a substituent and change the halomethyl group into an acidic group such as a sulfonic acid group or a carboxyl group to obtain a heat-resistant ion exchange resin (special feature JP-A-40-24398) and JP-A-58-157824 aim to improve the heat resistance by introducing a polyimide skeleton into the polymer chain, but the reaction process is complicated and the resin can be obtained quantitatively. Since it cannot be done, there is a big disadvantage in manufacturing.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention has been made in order to solve the above-mentioned various problems, and is excellent in heat resistance and has a chelate-forming ability, and therefore, a metal ion adsorbent even at a high temperature. An object of the present invention is to provide a polyamide that can be stably used as.

Means for Solving the Problems The polyamide of the present invention has a structure represented by formula I: X-YmX-Zn ... I (wherein, X is Y is -CO-A-CO-, A is a nitrogen-containing heterocycle, and Z is
Is Wherein R in X is hydrogen or a lower alkyl group,
m and n show the number of repetitions. ) The Y component is 5 to 95 mol% of the total amount of the acid mixture component, and the inherent viscosity (ηinh) is 0.3 to 2.5 dl / g (0.5 g of polyamide is dissolved in 100 ml of N-methylpyrrolidone and measured at 30 ° C). The present invention is a heat-resistant metal ion adsorbent comprising the above-mentioned polyamide.

As Y in the above formula I, A divalent organic group selected from is desirable.

When the polyamide of the present invention is used as a metal ion adsorbent, the component Y needs to be 5 to 95 mol% of the total amount of the acid mixture component. Ingredient Y is 5 mol% of the total unit
This is because when the amount is smaller, the chelating ability of the polyamide is too small to be practical. In the acid mixed component in the present invention, it is possible to use all of the acid components as the component Y, but when the amount of the component Y is large, it tends to be difficult to obtain a high molecular weight polymer. Since the content is 95 mol% or less, the range occupied by the component Y is 5 to 95 mol%, preferably 15 to 90 mol%.

The polyamide of the present invention generally has an inherent viscosity of 0.3 to 2.5 dl / g, preferably 0.5 to 1.5 dl / g.
5 g are dissolved in 100 ml of N-methylpyrrolidone and have a reading of 30 ° C.). If the inherent viscosity is too small, the polyamide does not have practical strength, while if the inherent viscosity is too large, difficulties may occur during the process of molding the polyamide into various shapes.

The present invention will be described in more detail below.

The polyamide of the present invention contains a diamine component (X component) and an acid mixture component composed of a heteroaromatic dicarboxylic acid component (Y component) and a phthalic acid component (Z component).

Diamine component (X component) contained in the polyamide of the present invention
Is made from a diamine represented by the following formula.

Here, R is hydrogen or a lower alkyl group such as a methyl group or an ethyl group. These diamine components are derived from the diamines used as raw materials, and those which provide such diamine components include 9,9-bis (4-aminophenyl) fluorene and 9,9-bis (3-methyl-
4-aminophenyl) fluorene and 9,9-bis (3
-Ethyl-4-aminophenyl) fluorene and the like.

In addition, the Z component of the acid mixture component is due to phthalic acid used as a raw material, and examples of such phthalic acids include terephthalic acid chloride. Incidentally, isophthalic acid may be used together with terephthalic acid as the phthalic acid component. In this case, from the viewpoint of heat resistance, the proportion of isophthalic acid is 50 mol% or less, preferably 30 mol% or less of the terephthalic acid component.

The heteroaromatic dicarboxylic acid used in the present invention is specifically The heterocycle and aromatic ring may each have an alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group. Preferred specific examples are dipicolinic acid, dinicotinic acid, 4-methyldipicolinic acid, 4-methyldinicotinic acid, 2,5-dicarboxylpyridine, 2,6-
Examples thereof include dicarboxyl pyrazine, 2,4-dicarboxypyrimidine, 3,6-dicarboxypyridazine and 4,7-dicarboxyquinoline.

Next, a method for synthesizing the polyamide of the present invention will be described.

The above-mentioned reaction between the diamine and the acid component is carried out by cooling in a solvent. As the reaction solvent, a solvent which is inert to the reaction, dissolves the above-mentioned raw materials, and dissolves the produced polyamide is preferable. As a preferable solvent, N-methyl-2-
Examples thereof include polar solvents such as pyrrolidone, N, N-dimethylformamide and N, N-dimethylacetamide.
The amount of the solvent used is not particularly limited, but the total weight of the reactants is 10
About 100 to 200 ml per g is suitable in terms of solubility and reaction time. The reaction temperature is 0 to 50 ° C, preferably 5 to 20 ° C
And a reaction time of 30 to 60 minutes is sufficient.

In the present invention, the raw materials are used so that the molar ratio of the diamine component and the carboxylic acid component is equal to obtain a polyamide having a high degree of polymerization. In addition, in order to carry out a sufficient reaction, it is preferable that the reaction solvent is dehydrated and dried with molecular sieves or the like. As the dehydrochlorinating agent used in the reaction, any dehydrochlorinating agent which is usually used can be used, but it is preferable to use triethylamine and pyridine, which are used by mixing in a reaction solvent.

The polyamide according to the present invention has a tertiary nitrogen in the aromatic ring in the polymer main chain and has a chelate-forming ability for metal ions by these, and therefore is suitable for use as a metal ion adsorbent. Moreover, since the polyamide of the present invention can be obtained in a solution state as described above, it can be easily molded into various shapes after filtering the produced hydrochloride, and the shape of powder, beads (spherical), film, membrane, etc. And can be used as a metal ion adsorbent. However, when the polyamide of the present invention is used as a metal ion adsorbent, the shape thereof is not limited.

For example, to obtain a polyamide resin powder, the polyamide solution may be gradually added to a solvent that is compatible with the reaction solvent and does not dissolve the polyamide, preferably water, alcohol or the like. Other than the above, acetone, ethylene glycol, etc. can be used as the coagulation solvent.

To obtain a bead-shaped resin, for example, a polyamide solution may be added in a droplet form to the above coagulation solvent to coagulate the polyamide. Further, in order to form the polyamide of the present invention into a film, the polyamide solution may be applied onto an appropriate substrate, such as a glass plate or a metal plate, and heated to evaporate the solvent. Further, the polyamide film can be obtained by applying the polyamide solution on the substrate and immersing it in the coagulation solvent.

A porous polyamide film can be obtained by dissolving a swelling agent composed of a metal salt soluble in a coagulation solvent in a polyamide solution and then immersing the solution in a coagulation solvent. The method for producing this porous membrane can be carried out according to the method described in, for example, JP-A-56-24007. As the above-mentioned metal salt, usual alkali metal salts and alkaline earth metal salts, preferably lithium, sodium, potassium chlorides, bromides, nitrates and the like can be used. The amount of such a swelling agent is 10 to 30 parts by weight per 100 parts by weight of polyamide. This is because if the amount used is too large, the uniformity of the polyamide solution tends to be impeded, and it becomes difficult to obtain a uniform film.

Since the polyamide of the present invention can be formed into various shapes as described above, it can be used for metal ion adsorption by various methods depending on the shape. For example, a resin is packed in a column and the like, and a solution containing metal ions to be adsorbed is passed through the column, or the resin is dipped in the solution.

In the polyamide according to the present invention, the amide skeleton constitutes a polymer main chain, and the main chain itself has the ability to form a chelate due to the tertiary nitrogen of the aromatic heterocycle. It has excellent heat resistance and strength, unlike metal ion adsorbents that have a functional group, withstands metal ion adsorption over a temperature range of up to 350 ° C
It is possible to practically adsorb metal ions over a temperature range of 0 ° C.

In particular, it is a great advantage that metal ions can be adsorbed in a high temperature range of 200 ° C. or higher, which is difficult to use with conventional ion exchange resins composed of styrene-divinylbenzene copolymers. In general, the rate of metal ion adsorption increases as the treatment temperature increases, so that the metal ion adsorbent of the present invention can significantly reduce the treatment time.

Furthermore, in the case of reactor water of a nuclear reactor in which the metal ion-containing solution is discharged at a high temperature, the metal ion can be immediately adsorbed without cooling the solution. Of course, it can also be used for metal ion adsorption at around room temperature.

The time for contacting the metal ion adsorbent comprising the polyamide of the present invention with the metal ion-containing aqueous solution is usually preferably about 5 minutes to 2 hours, but it may be appropriately selected depending on the application and purpose of use and is not limited thereto. is not.

In order to recover the metal ions adsorbed on the polyamide ion adsorbent of the present invention, similarly to the conventional ordinary metal ion adsorbent, the polyamide and the aqueous mineral acid solution may be contacted, whereby the polyamide metal ion adsorbent is It can be regenerated and reused.

Examples of the present invention will be described below.

Examples Example 1 34.8 g (100 mmol) of 9,9-bis (4-aminophenyl) fluorene was placed in a 1000 ml three-necked flask equipped with a stirrer.
And 20.2 g (200 mmol) of triethylamine were added and dissolved in 500 ml of N-methyl-2-pyrrolidone.

While maintaining the reaction tank at 10 to 15 ° C, 10.1 g (50 mmol) of terephthalic acid chloride and 10.2 g (50 mmol) of 2,6-pyridinedicarboxylic acid chloride were gradually added as a solid. 30
After stirring for 1 minute, the triethylamine.hydrochloride that had separated out was filtered to obtain a colorless transparent polyamide solution. Further, this was poured into methanol, the precipitate was filtered off, and dried to obtain the target polyamide resin.

The physical properties of the obtained polyamide have an inherent viscosity of 1.0 dl /
The glass transition temperature was 360 ° C.

Example 2 34.8 g (100 mmol) of 9,9-bis (4-aminophenyl) fluorene in a 1000-neck three-necked flask equipped with a stirrer.
And 20.2 g (200 mmol) of triethylamine were added and dissolved in 500 ml of N-methyl-2-pyrrolidone.

While maintaining the reaction tank at 10 to 15 ° C., 16.16 g (80 mmol) of terephthalic acid chloride and 4.08 g (20 mmol) of 2,6-pyridinedicarboxylic acid chloride were gradually added as a solid. 3
After stirring for 0 minutes, the precipitated triethylamine / hydrochloride was filtered to obtain a colorless transparent polyamide solution. Further, this was poured into methanol, the precipitate was filtered off, and dried to obtain the target polyamide resin.

The physical properties of the obtained polyamide have an inherent viscosity of 0.8 dl /
The glass transition temperature was 345 ° C.

Example 3 34.8 g (100 mmol) of 9,9-bis (4-aminophenyl) fluorene was placed in a 1000 ml three-necked flask equipped with a stirrer.
And 20.2 g (200 mmol) of triethylamine were added and dissolved in 500 ml of N-methyl-2-pyrrolidone.

In the same manner as in Example 1, 10.1 g (50 mmol) of terephthaloyl chloride and 10.2 g (50 mmol) of 2,5-pyridinedicarboxylic acid chloride were gradually added as a solid while maintaining the reaction tank at 10 to 15 ° C. After stirring for 30 minutes, the precipitated triethylamine / hydrochloride was filtered to obtain a colorless and transparent polyamide solution. Further, this was poured into methanol, the precipitate was filtered off, and dried to obtain the target polyamide resin.

The physical properties of the obtained polyamide have an inherent viscosity of 1.2 dl /
g, glass transition temperature was 350 ° C.

Example 4 34.8 g (100 mmol) of 9,9-bis (4-aminophenyl) fluorene was placed in a three-neck flask 1000 ml container equipped with a stirrer.
And 20.2 g (200 mmol) of triethylamine were added and dissolved in 500 mmol of N-methyl-2-pyrrolidone.

In the same manner as in Example 1, 10.1 g (50 mmol) of terephthalic acid chloride and 10.5 g (50 mmol) of 2,4-pyrimidinedicarboxylic acid chloride were gradually added as a solid while maintaining the reaction tank at 10 to 15 ° C. After stirring for 30 minutes, the precipitated triethylamine / hydrochloride was filtered to obtain a colorless and transparent polyamide solution. Further, this was poured into methanol, the precipitate was filtered off, and dried to obtain the target polyamide resin.

The physical properties of the obtained polyamide have an inherent viscosity of 0.8 dl /
The glass transition temperature was 360 ° C.

Comparative Example 1 34.8 g (100 mmol) of 9,9-bis (4-aminophenyl) fluorene was added to a three-necked flask 1000 ml container equipped with a stirrer.
And 20.2 g (200 mmol) of triethylamine were added and dissolved in 500 ml of N-methyl-2-pyrrolidone.

While maintaining the reaction tank at 10 to 15 ° C., 19.49 g (96 mmol) of terephthalic acid chloride and 0.816 g (4 mmol) of 2,6-pyridinedicarboxylic acid chloride were gradually added as a solid. 3
After stirring for 0 minutes, the precipitated triethylamine / hydrochloride was filtered to obtain a colorless transparent polyamide solution. Further, this was poured into methanol, the precipitate was filtered off, and dried to obtain the target polyamide resin.

The physical properties of the obtained polyamide have an inherent viscosity of 1.1 dl /
The glass transition temperature was 330 ° C.

(Evaluation of Performance as Metal Ion Adsorbent) 1 g of each of the polyamide powders obtained in Examples 1 to 4 and Comparative Example 1 was added to a 1,000 ppm aqueous solution of cobalt nitrate at 30 ° C.
Soak under shaking for 24 hours. Then, the residual cobalt ion concentration in the aqueous solution was measured by the base paper absorption method to determine the cobalt ion adsorption capacity of the polyamide resin of the present invention. The results are shown in Table 1.

Next, polyamide powder obtained in the above Examples and Comparative Examples and a commercially available metal ion adsorbent (Sumikaion KA900-manufactured by Sumitomo Chemical Co., Ltd., a three-dimensional copolymer of divinylpyridine and vinylpyridine) 1 g each in an autoclave After heating in hot water of ℃ for 7 days, it was cooled, and the cobalt ion adsorption amount was determined in the same manner as the above-mentioned method. The results are shown in Table 1.

From Table 1, it can be seen that the polyamide of the present invention has substantially no change in ion adsorption capacity even by heat treatment. on the other hand,
In the commercially available metal ion adsorbent, the polymer main chain was cut by heat treatment, and the particles were in a state of being finely crushed compared to before heating.

EFFECTS OF THE INVENTION The polyamide of the present invention has excellent heat resistance and moldability, has a chelate-forming ability, and can be stably supplied as a metal ion adsorbent at high temperatures. This can greatly contribute to the improvement of water pollution problems caused by heavy metals as ion adsorbents and the improvement of environmental problems such as the removal of industrial waste liquid.

Claims (3)

[Claims] 1. A structure represented by the formula I: X-YmX-Zn ... I (wherein X is Y is -CO-A-CO-, A is a nitrogen-containing heterocycle, and Z is
Is Wherein R in X is hydrogen or a lower alkyl group,
m and n show the number of repetitions. ) Y component is 5 to 95 mol% of the total amount of the acid mixture component, and has an inherent viscosity (ηinh) of 0.3 to 2.5 dl / g (0.5 g of polyamide is dissolved in 100 ml of N-methylpyrrolidone and measured at 30 ° C).
Is a polyamide. 2. Y of formula I is The polyamide according to claim 1, which is a divalent organic group selected from the group consisting of: 3. A heat-resistant metal ion adsorbent comprising the polyamide according to claim 1 or 2.