KR20110117318A - Ion exchange membrane comprising copolymer containing ion exchange group - Google Patents

Abstract

The present invention is (C10 ~ C30) isophthalic monomer having an ion exchange group; (C5-C20) glycol monomers; The present invention relates to an ion exchange membrane prepared by crosslinking a copolymer containing an ion exchange group prepared from an acid anhydride monomer with a crosslinking agent, and to a method for preparing the same, more specifically (C10 to C30) isophthalic monomer having an ion exchange group; (C5-C20) glycol monomers; Preparing a copolymer by stirring a solution for polymerization containing an acid anhydride monomer such as maleic anhydride and a reaction initiator; Forming a film by a solvent casting method using a reaction solution including the copolymer, a crosslinking agent and a photoinitiator; It relates to a method for producing an ion exchange membrane comprising the step of preparing a cation exchange membrane cross-linked by a photocrosslinking method using the membrane photoinitiator.
The ion exchange membrane according to the present invention is not only excellent in ion exchange capacity but also excellent in durability and improved in workability, and thus may be usefully used in composite membranes for water treatment and electrodialysis.

Description

ION EXCHANGE MEMBRANE COMPRISING COPOLYMER CONTAINING ION EXCHANGE GROUP}

The present invention is (C10 ~ C30) isophthalic monomer having an ion exchange group; (C5-C20) glycol monomers; The present invention relates to an ion exchange membrane prepared by crosslinking a copolymer containing an ion exchange group prepared from an acid anhydride monomer with a crosslinking agent, and a method for producing the same.

Ion-exchange membranes that are generally used are attracting worldwide attention for their clean process of renewable energy production that can reduce the environmental pollution by reducing the amount of fossil raw materials. . Recently, due to the rapid increase in the use of electronic products such as small notebooks, computers, mobile phones, ion exchange is being actively researched according to the necessity of developing a high-life, high-performance battery and the development of a new fuel cell as a core material.

Ion-exchange membranes can selectively separate cations and anions in aqueous solution, thus providing fuel cell, electrodialysis, water decomposition electrodialysis for acid and base recovery, diffusion dialysis to recover acid and metal species from pickling waste, ultrapure water process, etc. It is widely used, and in recent years, with the development of high-performance ion exchange membranes in developed countries, their application ranges are further expanded. However, in Korea, the technical accumulation of the ion exchange membrane production and application is very lacking, so it is urgent to develop new high-performance ion exchange membrane production technology through academic preoccupation and technology preoccupation in this field.

Commercially available ion exchange membranes used in fuel cell membranes and electrode membranes include sulfonated polystyrene and Nafion ^™ (hereinafter referred to as 'Nafion') manufactured by Du Pont. However, when the sulfonated polystyrene is dried, it is brittle due to an increase in brittleness, which makes it difficult to form a thin film or a composite film, and has a disadvantage in that it is inferior in mechanical stability during processing with an electrode. In order to improve this disadvantage, there is a method of lowering the sulfonation ratio of polystyrene or a method of increasing the thickness of the membrane. At this time, the ion exchange capacity of the membrane is remarkably decreased, and thus the performance as an ion exchange membrane cannot be expected. In addition, Nafion has been widely used as an ion exchange membrane due to high conductivity and chemical stability as a fluorine-based material, but has a disadvantage in that the price is very expensive due to the included fluorine compound and its use at high temperatures is limited.

As other ion exchange membrane materials, resins with excellent mechanical properties such as polybenzimidazole, polyphosphazene, PEEK, polysulfone, polyimide, polyetherimidazole and polyphenylene sulfide sulfone may be mixed and used as the base material of the cation exchange membrane. However, these membranes are expensive and the method of introducing the ion exchanger through functionalization after the preparation of the membrane reduces the surface properties of the membrane due to the functionalization introduction reaction, so that the mechanical properties are weak. Due to the disadvantage of using a low cost, there is a need for a new method to improve the mechanical properties.

The present invention is to solve the problems of the prior art as described above, (C10 ~ C30) isophthalic monomer having an ion exchange group; (C5-C20) glycol monomers; An object of the present invention is to provide an ion exchange membrane prepared by crosslinking a copolymer containing an ion exchange group prepared from an acid anhydride monomer with a crosslinking agent, and a method for preparing the same.

More specifically, (C10-C30) isophthalic monomer which has an ion exchange group; (C5-C20) glycol monomers; Preparing a copolymer by stirring a solution for polymerization containing an acid anhydride monomer such as maleic anhydride and a reaction initiator; Forming a film by a solvent casting method using a reaction solution including the copolymer, a crosslinking agent and a photoinitiator; The ion exchange membrane composition, which has excellent ion exchange capacity and excellent durability, and processability through the method of preparing an ion exchange membrane including the step of preparing a cation exchange membrane crosslinked by a photocrosslinking method using a photoinitiator, and using the same It is an object of the present invention to provide a method for producing an ion exchange membrane.

The present invention has been made to achieve the above object, the (C10 ~ C30) isophthalic monomer having an ion exchange group; (C5-C20) glycol monomers; Provided is an ion exchange membrane prepared by crosslinking a copolymer containing an ion exchange group prepared from an acid anhydride monomer with a crosslinking agent.

Hereinafter, the present invention will be described in more detail.

At this time, if there is no other definition in the technical terms and scientific terms used, it has a meaning commonly understood by those of ordinary skill in the art.

The present invention is (C10 ~ C30) isophthalic monomer having an ion exchange group; (C5-C20) glycol monomers; An ion exchange membrane prepared by crosslinking with a copolymer containing an ion exchange group prepared from an acid anhydride monomer and an ion exchange membrane prepared by a photocrosslinking method using a photoinitiator, wherein the copolymer has an ion exchange group (C10 to C30). 5-15 mol% of isophthalic monomers, 45-60 mol% of (C5-C20) glycol monomers and 25-40 mol% of acid anhydride monomers.

The isophthalic monomer in the copolymer preferably contains 5 to 15 mol%, preferably 5 to 10 mol%. If the isophthalic monomer is less than 5 mol%, the content of the ion exchange group contained in the isophthalate is lowered and the ion exchange capacity is lowered, so the performance as an ion exchange membrane cannot be expected. If the isophthalic monomer exceeds 15 mol%, brittleness is increased. As a result, molding as an ion exchange membrane becomes difficult.

The (C5-C20) glycol monomer in the copolymer is introduced to impart the flexibility of the copolymer, it is preferable to include 45 to 60 mol%. When the (C5-C20) glycol monomer is less than 45 mol%, the flexibility effect of the ion exchange membrane cannot be expected, and when it exceeds 60 mol%, durability due to swelling of the ion exchange membrane is lowered.

Acid anhydride monomer in the copolymer is introduced to improve the dimensional stability and mechanical properties through the crosslinking reaction, it is preferable to include 25 to 40 mol%. If the acid anhydride monomer is less than 25 mol%, crosslinking reaction is not sufficiently achieved, and mechanical properties cannot be expected to increase. If the acid anhydride monomer is more than 40 mol%, brittleness of the membrane surface is increased due to excessive crosslinking. The performance of the exchange membrane cannot be expected.

The (C10 to C30) isophthalic monomers containing the ion exchange group include dimethyl isophthalate, diphenyl isophthalate, dimethyl 4,6-bis (benzyloxy) isophthalate (Dimethyl 4,6- It is preferable to use any one or two or more mixtures in which an ion exchange group is introduced in the benzene ring among isophthalic systems such as bis (benzyloxy) isophthalate) and dibutyl isophthalate.

Examples of the ion exchange group include a cation exchange group or a quaternary ammonium salt (-NH 3) selected from a sulfonic acid group (-SO 3 H), a carboxyl group (-COOH), a phosphonic group (-PO 3 H 2), and a phosphonic group (-HPO 2 H). Anion exchange groups selected from tertiary amines (-NH2, -NHR, -NR2) and quaternary phosphonium groups (-PR4) can be suitably used.

In addition, when the carbon number of the alkyl group forming the (C5-C20) glycol-based or methacrylate-based monomer is more than 20, it is not suitable for the polymerization reaction, and thus the target effect in the present invention cannot be obtained, thus maintaining C5-C20. Good to do. As a specific example, any one or a mixture selected from diethylene glycol, butyl glycol, hexylene glycol, neopentyl glycol, propylene glycol, and propylene glycol may be used. In terms of the effect of the reaction, it is preferable to use diethylene glycol.

Acid anhydride monomers used to improve the durability of the ion exchange membrane through the crosslinking reaction include maleic anhydride, phthalic anhydride, and the like. will be.

The ion exchange membrane according to the present invention,

a) (C10 to C30) isophthalic monomer having an ion exchange group; (C5-C20) glycol monomers; Preparing a copolymer by stirring a solution for polymerization comprising an acid anhydride monomer and a reaction initiator;

b) forming a film by a solvent casting method using a reaction solution including the copolymer, a crosslinking agent and a photoinitiator;

c) preparing an ion exchange membrane crosslinked with a photoinitiator using a photoinitiator;

It can be prepared by a process comprising a.

The reaction initiator of step a) may be used without particular limitation, and in particular, in the present invention, benzoyl peroxide (BPO), dicumyl peroxide (DCP), azobisisobutyronitrile; AIBN), Butylstannoic acid (BuSnOOH) and the like can be used, but is not limited thereto. Preferably, the reaction initiator is added in an amount of 0.1 to 0.5% by weight. If less than 0.1% by weight, sufficient crosslinking does not occur, so that terpolymerization is difficult. When the reaction initiator exceeds 0.5% by weight, the content of the reaction initiator itself is too high. There is a problem that degradation occurs.

(C10 to C30) isophthalic monomer having an ion exchange group in step a); (C5-C20) glycol monomers; The acid anhydride monomer is polymerized in a two-step reaction, and after the reaction, the unreacted material can be removed by a vacuum desolvent method.

Although the crosslinking agent used in step b) finally plays a role in determining the swelling degree and the degree of crosslinking of the membrane, the present invention is not particularly limited, but in the present invention, polyfunctional amide, polyfunctional acrylate, and polyfunctional isocyanate may be used. It is not limited to this. Such a crosslinking agent is preferably added in 10 to 30% by weight, when less than 10% by weight, the degree of crosslinking is insufficient, and when it exceeds 30% by weight, the crosslinking degree is too high, causing a problem of film breakage.

In addition, the photoinitiator of step b) is not particularly limited to play a role of promoting the crosslinking reaction during crosslinking, but in the present invention, benzophenone series and thioxantone series may be used, but the present invention is not limited thereto. Such photoinitiator is preferably added in 1.0 to 5.0% by weight, if less than 1.0% by weight, there is a problem that can not act as a cross-linking promotion due to the small amount, if it exceeds 5.0% by weight crosslinking reaction due to the addition of excess The problem of physical property degradation occurs.

When the membrane is formed by the solvent casting method of step b), the thickness of the membrane is preferably 80 to 150 μm, and the ion exchange capacity of the ion exchange membrane is excellent as well as durability in the above range.

The forming of the film by the crosslinking of step c) uses a photocrosslinking method, and crosslinking occurs by UV irradiation.

The ion exchange membrane according to the present invention has not only an excellent ion exchange capacity through synthesis of a copolymer containing an ion exchange group and an ion exchange membrane, but also excellent durability and flexibility.

(C10 to C30) isophthalic monomer having an ion exchange group according to the present invention; (C5-C20) glycol monomers; The present invention relates to an ion exchange membrane prepared by crosslinking a copolymer containing an ion exchange group containing an acid anhydride monomer with a crosslinking agent and a method for preparing the same. Since the functionalization reaction is not required after the preparation of the membrane, there is no deterioration in the physical properties of the membrane surface due to the functionalization reaction, so that the durability is excellent and the workability is improved. In addition, through the introduction of an anhydride system that improves dimensional stability and mechanical properties through crosslinking reaction with a flexible (C5 ~ C20) glycol monomer, it is possible to manufacture a membrane with high ion exchange capacity, excellent durability.

Hereinafter, the present invention will be described in more detail with reference to Examples, which are intended only for understanding the constitution and effects of the present invention, and are not intended to limit the scope of the present invention.

[ Example  One]

When the copolymer is mixed, 10 mol% of dimethyl 5-sulfoisophthalate sodium salt (DMISP), which is an isophthalic group containing ion exchange group, and 60 mol% of diethylene glycol (DEG) are mixed and mixed in a 1L flask. Stir at a temperature of 200 ° C. until. After stirring, 0.1 wt% of butyltin acid (BuSnOOH), which is a reaction initiator, was added thereto, and polymerization was performed at 230 ° C. for 5 hours. At this time, the reaction byproduct methanol is removed. After completion of the first reaction, the temperature was lowered to 80 ° C., and 30 mol% of maleic anhydride (MAn) was added, and then 0.1 wt% of butyltin acid (BuSnOOH), a reaction initiator, was added thereto. After the addition, the reaction temperature was raised to 200 ° C., and then reacted for 4 hours to prepare a DMSIP / DEG / MAn terpolymer. After completely dissolving the prepared DMSIP / DEG / MAn terpolymer in dimethyl acetamide (DMAc), 20 wt% of pentaerythritol tetraacrylate (PETA) block isocyanate as a crosslinking agent and 3.0 wt% of benzophenone (BP) as a photoinitiator were added. Add and stir for 6 hours. After stirring, the film was formed into a film having a thickness of 100 μm using a solvent casting method, dried at room temperature for 3 hours, and crosslinked using a constant strength in a UV irradiator to prepare a film.

[ Example  2]

Except that 12.5 mol% of isophthalic dimethyl 5-sulfoisophthalate sodium salt (DMISP) and 55 mol% of diethylene glycol (DEG) were used for the synthesis of the copolymer and 32.5 mol% maleic anhydride (MAn) in the second reaction. Then, the same procedure as in Example 1 was carried out to prepare an ion exchange membrane.

[ Example  3]

Except for the use of isophthalic dimethyl 5-sulfoisophthalate sodium salt (DMISP) and 60 mol% of diethylene glycol (DEG) and 25 mol% of maleic anhydride (MAn) in the second reaction for copolymer synthesis Then, the same procedure as in Example 1 was carried out to prepare an ion exchange membrane.

[ Comparative example  One]

Membrane was prepared in the same manner as in Example 1 except that dimethyl isophthalate containing no ion exchange group was used instead of dimethyl 5-sulfoisophthalate sodium salt (DMISP) containing the ion exchange group of Example 1.

[ Comparative example  2]

After the ion exchange membrane was prepared in the same manner as in Comparative Example 1, the membrane was immersed in 95% sulfuric acid to which silver sulfate was added as a sulfonation initiator, followed by sulfonation at room temperature for 2 hours. After the completion of the phonation reaction, the solution was washed several times with sulfuric acid (70%, 50%, 20% by weight), and finally, unreacted sulfuric acid was removed using distilled water. The washed membrane was dried in a vacuum oven at 50 ℃ for 24 hours to prepare an ion exchange membrane.

[ Test Example  One]

The performance of the ion exchange capacity and mechanical properties of the ion exchange membranes prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were measured, and the results are shown in Table 1 below.

Ion exchange capacity measurement

The dried ion exchange membrane was first washed with 1N HCl aqueous solution, and then washed twice with distilled water until the pH was neutral. After drying in a vacuum oven at 50 ° C. for at least one day, the dried ion exchange membrane is weighed and placed in a 200 mL Erlenmeyer flask. 100 mL of 0.1N NaOH aqueous solution was added and stirred at room temperature for 24 hours. Then, after titration with 0.1N HCl solution, the ion exchange capacity was measured using the following equation.

V _HCl and V _NaOH are the total volumes of HCl and NaOH used for the titration, and N _HCl and N _NaOH represent the normal concentrations of HCl and NaOH.

Mechanical property measurement The tensile strength )

Tensile strength for measuring the durability of the ion exchange membrane was measured by using a tensile strength tester. The specimen was a dumbbell 100 mm long, 25 mm wide and 5 mm wide. The specimen was 20 mm long and 5 mm wide. The strain-stress curve when the test piece was stretched was measured by the method of stress on the elongation from the initial stage to the break, and the tensile strength was confirmed by the method of ASTM D 882.

As shown in Table 1, in the case of the ion exchange membrane prepared in Examples 1 to 3, the membrane is unstable due to the DMSIP / DEG / MAn terpolymerization effect containing the ion exchanger than the ion exchange membrane prepared in Comparative Examples 1-2. It was confirmed that the ion exchange capacity was very high as shown without being brittle. In addition, in the case of Comparative Example 1, the ion exchange capacity was lowered as compared with the example when no ion exchanger was introduced. In addition, the ion exchange membranes prepared in Examples 1 to 3 exhibited significantly improved mechanical strength (tensile strength) than the ion exchange membranes prepared in Comparative Examples 1 and 2. In Comparative Example 2, the ion exchange capacity was higher than that of Comparative Example 1 by introduction of an ion exchanger through sulfonation after membrane preparation, but in the case of tensile strength which is a measure of durability, Examples 1 to 3 and Comparative Example 1 In contrast, the results were lowered.

Claims (4)

(C10 to C30) isophthalic monomer having an ion exchange group; (C5-C20) glycol monomers; An ion exchange membrane prepared by crosslinking a copolymer containing an ion exchange group prepared from an acid anhydride monomer with a crosslinking agent. The method of claim 1,
The (C10 to C30) isophthalic monomer having the ion exchange group is an ion into which an ion exchange group selected from dimethyl isophthalate, diphenyl isophthalate, dimethyl 4,6-bis (benzox) isophthalate or dibutyl isophthalate is introduced. Exchange membrane. The method of claim 1,
The (C5 ~ C20) glycol system is an ion exchange membrane selected from diethylene glycol, butyl glycol, hexylene glycol, neopentyl glycol or propylene glycol. The method of claim 1,
The acid anhydride monomer is maleic anhydride or phthalic anhydride.