KR101137313B1 - Manufacturing method of copolymer for ion exchange membrane - Google Patents

Abstract

The present invention is a styrene; (C1-C20) alkyl acrylate type or methacrylate type; The present invention relates to a method for producing a copolymer for producing an ion exchange membrane including a hydroxy (C 1 to C 20) alkyl acrylate type or a methacrylate type, wherein the copolymer for preparing an ion exchange membrane can be sulfonated to prepare an ion exchange membrane. More specifically, a polymerization solution comprising a styrene monomer, a (C1 to C20) alkyl acrylate or methacrylate monomer, a hydroxy (C1 to C20) alkyl acrylate or methacrylate monomer and a reaction initiator Stirring to prepare a copolymer; Forming a film by a solvent casting method using a reaction solution including the copolymer, a crosslinking agent, and a thermal initiator; A method for producing an ion exchange membrane comprising a, forming a group ^- (-SO ₃₎ sulfonic acid cation-exchange membrane to the sulfonation.

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 an electrodialysis composite membrane.

Ion exchange membrane, styrene type, acrylate type, methacrylate type, sulfonic acid group

Description

Manufacturing method of copolymer for preparing ion exchange membrane {Manufacturing method of copolymer for ion exchange membrane}

The present invention is a styrene; (C1-C20) alkyl acrylate type or methacrylate type; The present invention relates to a method for producing a copolymer for producing an ion exchange membrane comprising a hydroxy (C1 to C20) alkyl acrylate type or a methacrylate type and an ion exchange membrane prepared by sulfonating the copolymer for preparing an ion exchange membrane.

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, the developed range of high-performance ion exchange membrane is developed in developed countries. 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 have the disadvantage of using plasticizers due to their weak mechanical properties. Therefore, there is a need for a new method for improving low cost and mechanical properties.

The present invention is to solve the problems of the prior art as described above, styrene-based; (C1-C20) alkyl acrylate type or methacrylate type; It is an object of the present invention to provide a method for preparing an ion exchange membrane copolymer comprising a hydroxy (C 1 -C 20) alkyl acrylate type or a methacrylate type and an ion exchange membrane prepared by sulfonating the copolymer for preparing an ion exchange membrane.

More specifically, a polymerization solution containing a styrene monomer, a (C1 to C20) alkyl acrylate or methacrylate monomer, a hydroxy (C1 to C20) alkyl acrylate or methacrylate monomer and a reaction initiator Stirring to prepare a copolymer; Forming a film by a solvent casting method using a reaction solution including the copolymer, a crosslinking agent and a thermal initiator; The membrane sulfonated to the sulfonic acid to the cation-exchange group (-SO ₃ ^-) and forming a group; excellent durability as well as the ion exchange capacity of solid through the manufacturing method of the ion exchange membrane comprising a workability is improved ion-exchange membranes for producing copolymer And it is an object of the present invention to provide a method for producing an ion exchange membrane using the same.

The present invention has been made to achieve the above object, a styrene-based; (C1-C20) alkyl acrylate type or methacrylate type; It provides a method for producing a copolymer for producing an ion exchange membrane comprising a hydroxy (C1 ~ C20) alkyl acrylate-based or methacrylate-based and an ion exchange membrane prepared by sulfonating the copolymer for producing an ion exchange membrane.

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

In this case, unless there is another definition in the technical terms and scientific terms used, it has the meaning that is commonly understood by those of ordinary skill in the art, unnecessarily obscure the subject matter of the present invention in the following description Description of known functions and configurations that may be omitted.

The present invention is a styrene; (C1-C20) alkyl acrylate type or methacrylate type; The present invention relates to a method for preparing a copolymer for producing an ion exchange membrane comprising a hydroxy (C 1 to C 20) alkyl acrylate type or a methacrylate type and to an ion exchange membrane prepared by sulfonating the copolymer for preparing an ion exchange membrane. 45 to 65 wt% of styrene monomer, 15 to 30 wt% of (C1-C20) alkyl acrylate or methacrylate monomer, and 5 to 25 hydroxy (C1-C20) alkyl acrylate or methacrylate monomer Contains by weight.

Styrene-based monomer in the copolymer is preferably included 45 to 65% by weight, more preferably 50 to 60% by weight. If the styrene-based monomer is less than 45% by weight, the content of sulfonation reaction is lowered and the ion exchange capacity is lowered, so that the performance as an ion exchange membrane cannot be expected. Molding becomes difficult.

The (C1-C20) alkyl acrylate-based or methacrylate-based monomer in the copolymer is introduced to impart the flexibility of the copolymer, it is preferable to include 15 to 30% by weight. When the (C1-C20) alkyl acrylate-based or methacrylate-based monomer is less than 15 wt%, the flexibility effect of the ion exchange membrane cannot be expected, and when it exceeds 30 wt%, the swelling ratio of the ion exchange membrane is increased. have.

The hydroxy (C1 ~ C20) alkyl acrylate-based or methacrylate-based monomer in the copolymer is introduced to improve the dimensional stability and mechanical properties through the crosslinking reaction, it is preferable to include 5 to 25% by weight. When the hydroxy (C1 ~ C20) alkyl acrylate-based or methacrylate-based monomer is less than 5% by weight cross-linking reaction is not sufficiently achieved, the mechanical properties can not be expected to increase, if it exceeds 25% by weight Due to excessive crosslinking during the sulfonation reaction, the sulfonation reaction is inhibited, thereby lowering the ion exchange capacity, and thus the performance of the ion exchange membrane cannot be expected.

The styrene monomer may be any one or a mixture of two or more selected from ethylbenzene, divinylbenzene, p-ethylvinylbenzene, and styrene monomer. Is to use a styrene monomer (SM).

In addition, when the carbon number of the alkyl group forming the (C1-C20) alkyl acrylate-based or methacrylate-based monomer is more than 20, it is not suitable for the polymerization reaction, and thus the effect desired in the present invention cannot be obtained. It is good to keep it. Specific examples include methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), Lauryl methacrylate (LMA), ethyl methacrylate (EMA), n-butyl methacrylate (BMA), n-hexyl methacrylate (n-hexyl methacrylate, The use of any one or mixtures of two or more selected from HMA) is good in terms of the effectiveness of the reaction, most preferably using lauryl methacrylate (LMA).

When the carbon number of the alkyl group forming the hydroxy (C1 ~ C20) alkyl acrylate-based or methacrylate-based monomer also exceeds 20, it is preferable to maintain the C1 ~ C20 because it is not suitable for the polymerization reaction. Specific examples include hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), 2-hydroxyethyl methacrylate (2-HEMA), and hydroxypropyl meta. It is preferable to use any one or two or more mixtures selected from hydroxypropyl methacrylate (HPMA) and glycidal methacrylate (GMA) in terms of the effect of the reaction, and most preferably hydroxyethyl acrylate (HEA ).

The ion exchange membrane according to the present invention,

a) stirring a solution for polymerization containing a styrene monomer, a (C1 to C20) alkyl acrylate or methacrylate monomer, a hydroxy (C1 to C20) alkyl acrylate or methacrylate monomer and a reaction initiator To prepare a copolymer;

b) forming a film by a solvent casting method using a reaction solution containing the copolymer, a crosslinking agent and a thermal initiator;

to form a group) ^- c) a sulfonic acid (-SO ₃ a cation-exchange group to sulfonation the membrane;

It can be prepared by a process comprising a.

The reaction initiator of step a) may be used without particular limitation, and in the present invention, benzoyl peroxide (BPO), dicumyl peroxide (DCP), azobisisobutyronitrile (AIBN), etc. may be used, but is not limited thereto. The reaction initiator is preferably added in 0.2 ~ 0.7% by weight, when less than 0.2% by weight does not cause sufficient crosslinking is difficult ternary copolymerization, when the content exceeds 0.7% by weight is too high in the content of the reaction initiator itself deteriorated physical properties There is a problem that happens.

The styrene monomer, the (C1-C20) alkyl acrylate or methacrylate monomer, the hydroxy (C1-C20) alkyl acrylate or methacrylate monomer of step a) is at a temperature of 80 ~ 100 ℃ The polymerization takes place, and after the reaction, the unreacted material can be removed by vacuum desolvent method.

The crosslinking agent used in step b) finally plays a role in influencing the swelling degree and the degree of crosslinking of the membrane, but the present invention is not limited thereto. However, the present invention is not limited thereto. Such a crosslinking agent is preferably added in an amount of 5 to 30% by weight, and when less than 5% by weight, the degree of crosslinking is insufficient. When the amount of the crosslinking agent is more than 30% by weight, the crosslinking degree is so high that brittleness of the membrane occurs.

In addition, the thermal initiator of step b) is not particularly limited to promote a crosslinking reaction during crosslinking, but in the present invention, benzoyl peroxide (BPO), dicumyl peroxide (DCP), azobisisobutyronitrile (AIBN), and the like may be used. It is not. It is preferable that such a thermal initiator is added in an amount of 0.2 to 1.5% by weight, and if it is less than 0.2% by weight, there is a problem in that it cannot serve as a crosslinking promoting agent. In the reaction, a problem of deterioration of physical properties 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 in this range, the ion exchange capacity of the ion exchange membrane is excellent as well as excellent in durability.

Forming the film of step b) is preferably carried out at 25 ~ 150 ℃, crosslinking occurs in the temperature range.

Next, the above c) was deposited a film of step b) in 95% sulfuric acid for the step of sulfonation sulfonic acid (-SO ₃ cation ^exchanger may form a group), the ion exchange membrane according to the invention the concentration of the sulfonic acid group The high ion exchange capacity is not only high, but also has excellent durability and flexibility.

Styrene system according to the present invention; (C1-C20) alkyl acrylate type or methacrylate type; The ion exchange membrane prepared by sulfonating a copolymer for preparing an ion exchange membrane and a copolymer for preparing an ion exchange membrane comprising a hydroxy (C 1 -C 20) alkyl acrylate or a methacrylate type has an excellent ion exchange capacity by forming sulfonic acid groups. In addition, it is excellent in durability and workability is improved. In addition, the introduction of hydroxy (C1-C20) alkyl acrylate- or methacrylate-based monomers to improve the dimensional stability and mechanical properties through crosslinking reaction with flexible (C1-C20) alkyl acrylate-based or methacrylate-based monomers Through the ion exchange capacity, high durability and flexible membrane can be produced.

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 1

For copolymer synthesis, 55% by weight of styrene monomer (SM), 20% by weight of hydroxyethyl acrylate (HEA) and 25% by weight of lauryl methacrylate (LMA) were mixed and placed in a 1L flask. 500 mL of dichloroethane (DCE) and 0.4 wt% of t-butyl peroxide (PO) as a reaction initiator were added, and polymerization was performed at 80 ° C. for 10 hours. After the reaction, the unreacted product was removed by vacuum desolvent method to prepare a SM / HEA / LMA terpolymer. After completely dissolving the prepared SM / HEA / LMA terpolymer in 1,2-Dichloroethane (DCE), 20 wt% of crosslinking agent blocked isocyanate and 1.0 wt% of thermal initiator Benzoyl peroxide (BPO) were added and stirred for 6 hours. It was. After stirring, the film was formed into a thickness of 120 μm using a solvent casting method, dried at room temperature for 3 hours, sequentially heated to a vacuum oven at 150 ° C., crosslinked for 3 hours, and then dried at room temperature for 1 hour to prepare a membrane. It was. The membrane was immersed in 95% sulfuric acid added with silver sulfate as a sulfonation initiator, and then sulfonated at room temperature for 2 hours. After completion of the sulfonated reaction, sulfuric acid (70%, 50%, 20% wt%) by concentration Net), 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.

[Example 2]

The same procedure as in Example 1 was used except that 60 wt% of styrene monomer (SM), 20 wt% of hydroxyethyl acrylate (HEA) and 20 wt% of lauryl methacrylate (LMA) were used for the copolymer synthesis. To prepare an ion exchange membrane.

Example 3

The same procedure as in Example 1 was used except that 65 wt% of styrene monomer (SM), 20 wt% of hydroxyethyl acrylate (HEA), and 15 wt% of lauryl methacrylate (LMA) were used for the copolymer synthesis. To prepare an ion exchange membrane.

Comparative Example 1

An ion exchange membrane was prepared in the same manner as in Example 1 except that polystyrene (Mw; 180,000) was used instead of the styrene monomer (SM), hydroxyethyl acrylate (HEA), and lauryl methacrylate of Example 1. Prepared.

Comparative Example 2

Except for using 80% by weight of styrene monomer (SM), 10% by weight of hydroxyethyl acrylate (HEA) and 10% by weight of lauryl methacrylate (LMA) for the synthesis of the copolymer as in Example 1 To prepare an ion exchange membrane.

[Test Example 1]

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 (tensile strength)

Tensile strength of the ion exchange membrane was measured using a tensile strength tester. The specimen was a 100 mm long, 25 mm wide and 5 mm wide dumbbell. A 20 mm long, 5 mm wide specimen was used to stretch the specimen. The stress-stress curve was measured by the stress on the elongation from the beginning to the break, and the tensile strength was determined by the method of ASTM D 882.

[Table 1] Evaluation of ion exchange capacity and mechanical properties of ion exchange membrane

As shown in Table 1, in the case of the ion exchange membrane prepared in Examples 1 to 3, the membrane is not unstable due to the three-way copolymerization effect of Sty / HEA / LMA than the ion exchange membrane prepared in Comparative Examples 1 to 2. As can be seen, very high ion exchange capacity was observed. 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.

Claims (9)

delete delete delete delete delete delete a) 45 to 65% by weight of styrene-based monomers, 15 to 30% by weight of (C1-C20) alkyl acrylate-based or methacrylate-based monomers, hydroxy (C1-C20) alkyl acrylate-based or methacrylate-based monomers 5 Preparing a copolymer by stirring a solution for polymerization containing ˜25 wt% and a reaction initiator 0.2˜0.7 wt%; b) forming a film by using a reaction solution containing the copolymer, a crosslinking agent and a thermal initiator in a thickness of 80 to 150 μm by a solvent casting method, and then crosslinking at 25 to 150 ° C. to form a film; to form a group) ^- c) a sulfonic acid (-SO ₃ a cation-exchange group to sulfonation the membrane; Method for producing an ion exchange membrane comprising a. delete delete