KR101836410B1 - Styrene-tert-butyl styrene based cation exchange composite membranes with plasticizers and method for preparing the same - Google Patents

Abstract

The present invention provides a cation exchange composite membrane configured to include a sulfonated styrene-tert-butylstyrene-based copolymer represented by chemical formula 1 and a plasticizer. A cation exchange composite membrane configured to include a sulfonated styrene-tert-butylstyrene-based copolymer and a plasticizer of the present invention has enhanced ion exchange capacity, mechanical properties, chemical properties and processability while having low electrical resistance, is easy to control ion exchange capacity and ionic conductivity, and has ionic conductivity superior to that of the conventional cation exchange composite membrane. Moreover, the membrane of the present invention can be manufactured more easily than the conventional cation exchange composite membrane, and also has low cost.

Description

[0001] The present invention relates to a styrene-tert-butylstyrene-based cation exchange composite membrane containing a plasticizer and a method for preparing the same,

TECHNICAL FIELD The present invention relates to a cation exchange composite membrane containing a plasticizer and a method for producing the composite membrane. More specifically, the present invention relates to a method for producing a cation exchange membrane, which includes a plasticizer in a styrene-terbutylstyrene- To a cation exchange composite membrane which improves the electrochemical characteristics and a method for producing the same.

The ion-exchange membrane is a type of polymer membrane, which can selectively separate anions or cations through electrostatic principles depending on the type of ion-exchangeable group introduced into the membrane. In the case of the cation exchange membranes used for commercial purposes, ion exchangers are largely classified into strong acid sulfonic acid groups (-SO ₃ ^- ) and weakly acidic carboxylic acid groups (-COO ^- ). In the case of anion exchange membranes, And an ammonium chloride group (-NH ³⁺ ) as an ion-exchange group.

The separation process using such an ion exchange membrane enables separation and purification of comparatively high purity as compared with the separation process using distillation or chemical treatment, low consumption of energy, simple equipment and low investment cost, and continuous process is possible And has been attracting attention as a separation and refining process in various industrial fields because it has excellent processing ability per hour.

Currently, ion-exchange membranes are used for electrodialysis, desalting and electrodialysis for desalination or purification to remove heavy metals or other harmful ionic substances harmful to human body, water-splitting electrodialysis, Diffusion dialysis, desalination of seawater or surface water, and electrodeionization for the production of ultrapure water for semiconductor or power generation, and its application field is also expanding. In general, commercial membranes should have high ion selective permeability (> 0.95 - 0.98), low electrical resistance (<3.0 - 4.0 Ω / cm ² ), adequate water content, high mechanical strength and chemical resistance.

Conventionally, an ion exchange membrane was produced by a manufacturing process using a copolymer of styrene-divinylbenzene or vinylbenzyl chloride-divinylbenzene as a base material, a bulk polymerization method, a latex method and a paste method.

Bulk polymerization is a polymerization method in which a solvent is not used and polymerization is carried out by adding an initiator to the monomer alone or by adding an initiator to the monomer. However, when the above-mentioned bulk polymerization is carried out by using only a styrene-divinylbenzene monomer alone, the brittleness is increased and the mechanical properties are lowered. Therefore, a support capable of reinforcing mechanical strength should be used. In order to obtain a thin film, There is a problem that the manufacturing cost of the entire membrane is increased.

The latex method is a method in which a copolymer of styrene-divinylbenzene or a latex of a styrene-butadiene copolymer is dipped in a support and dried, and then a basic membrane is formed through crosslinking by oxidative crosslinking, And introducing an ion exchanger through a reaction, chloromethylation reaction or quaternary amination reaction. However, the latex method has a problem that the mechanical properties and electrochemical characteristics of the membrane may be lowered due to the influence of the emulsifier remaining in the latex of the polymer.

On the other hand, the paste method is a method in which a paste is prepared by using a styrene-divinylbenzene monomer, a copolymer powder thereof, a rubber additive, and the like, Or the latex method is superior in mechanical properties and electrochemical properties. However, in order to obtain more improved mechanical properties, an additive must be added. The complexity of such a manufacturing process causes a rise in the manufacturing cost of the film, and the film is broken and the chemical stability is lowered during drying Y. Mizutani, Structure of ion-exchange membranes, J. Member Sci. 49 (1990) 121).

Conventionally, Patent Document 1 discloses a method of absorbing vinylbenzyl chloride, swelling-promoting monomer, divinylbenzene, and a photoinitiator using a nonporous low-density polyethylene film as a support, which simultaneously exhibits monomer absorbability and photo-crosslinking properties, And then introducing an anion-exchange group through a quaternary amination reaction to produce an anion exchange membrane. However, the strength of the support itself is too low in the ion-exchange membrane produced by the above method, and it is difficult to commercially produce the ion-exchange membrane due to high brittleness after introduction of the ion exchanger.

Patent Document 2 discloses a porous film produced by a series of manufacturing processes in which a polymerization solution containing a styrenic monomer, a vinylbenzyl monomer, a crosslinking agent and an initiator is impregnated with a porous film and polymerized to form an introduction of ammonium ion Discloses an anion exchange composite membrane containing a styrene-vinylbenzene-based copolymer. The anion exchange membranes prepared by the above method do not use additives for improving the mechanical strength, and thus they are deficient in terms of high strength and high impact resistance.

Further, Patent Document 3 discloses a cation exchange composite membrane comprising a styrene-ter-butylstyrene-olefin-based copolymer into which a sulfonated group is introduced. Since the cation exchange composite membrane contains an expensive olefinic additive, there is a problem in that it is not economical and the olefinic additive has a low reactivity, which makes it difficult to produce the copolymer. In addition, the cation exchange composite membrane has a problem of insufficient physical properties and ionic conductivity.

However, as described above, the plasticizer is added to the polymerization solution in which the sulfonation reaction activity of the present invention, the styrene-based monomer, the sulfonation-inactive tert-butylstyrene monomer, the crosslinking agent and the initiator are mixed, There has not been reported an invention relating to a method for producing a cation exchange composite membrane by immersing the support in a supporter of a polymer electrolyte membrane to saturate the interior, followed by thermal crosslinking polymerization, and then introducing a sulfonating group.

Accordingly, the present inventors have been interested in a method for producing a cation exchange composite membrane having a simple manufacturing process, low manufacturing cost, and excellent conductivity, mechanical strength, and chemical resistance, and the cation exchange composite membrane of the present invention is subjected to ion exchange The present invention has been accomplished by confirming that it has superior ability, low electric resistance, and excellent processability.

Patent Document 1: Korean Patent No. 10-0542295 Patent Document 2: Korean Patent No. 10-0999048 Patent Document 3: Korean Patent No. 10-1190732

It is an object of the present invention to provide a cation exchange complex having a low electric resistance and excellent ion exchange ability, processability, mechanical properties and chemical resistance, easy control of ion exchange capacity and ion conductivity, improved brittleness of a composite membrane, To provide a membrane.

It is also an object of the present invention to provide a method for producing the above cation exchange composite membrane.

In order to achieve the above object,

There is provided a cation exchange composite membrane comprising a sulfonated styrenic-tert-butyl styrenic copolymer represented by the following formula (1) and a plasticizer.

&Lt; Formula 1 >

(In the formula 1,

"은 랜덤 공중합체를 나타낸다)"

"Represents a random copolymer)

In addition,

Impregnating a polymeric solution comprising a styrene-based monomer, a tert-butylstyrene-based monomer, a plasticizer, a crosslinking agent and an initiator with a support in the form of a fabric (step 1);

Preparing a composite membrane comprising a cross-linked styrene-ter-butyl styrenic copolymer and a plasticizer by adding a styrene-based monomer, a tert-butyl styrene-based monomer and a plasticizer in a cloth-shaped support impregnated in step 1 above (Step 2); And

(Step 3) of reacting chlorosulfonic acid or sulfuric acid with a composite membrane composed of the styrene-ter-butyl styrenic copolymer and plasticizer of step 2 and introducing a sulfonated group with a cation exchanger to prepare a cation- The present invention also provides a method for producing a cation exchange composite membrane.

Further,

There is provided a composite membrane module comprising a cation exchange composite membrane comprising a sulfonated styrene-based tert-butyl styrene copolymer and a plasticizer represented by the above formula (1).

Further,

The present invention provides a separation and purification process using a composite membrane module comprising a cation exchange membrane comprising a sulfonated styrene-tert-butyl styrene copolymer and a plasticizer represented by the above formula (1) and a plasticizer.

The cation exchange composite membrane comprising the sulfonated group-containing styrene-ter-butyl styrenic copolymer and the plasticizer of the present invention not only has improved ion exchange capacity, mechanical properties, chemical properties and processability while having low electrical resistance It is very easy to control the ion exchange ability and the ion conductivity and has an ion conductivity superior to that of the conventional cation exchange composite membrane. In addition, compared with the conventional cation exchange composite membrane, it is easy to manufacture and has a low cost.

The present invention

There is provided a cation exchange composite membrane comprising a sulfonated styrenic-tert-butyl styrenic copolymer represented by the following formula (1) and a plasticizer.

&Lt; Formula 1 >

(In the formula 1,

"은 랜덤 공중합체를 나타낸다)"

"Represents a random copolymer)

Hereinafter, the cation exchange composite membrane according to the present invention will be described in detail.

The cation exchange composite membrane according to the present invention is characterized in that it comprises a sulfonated styrene-ter-butyl styrenic copolymer and a plasticizer, and the cation exchange membrane according to the present invention is characterized in that the ion exchange membrane Mechanical properties, chemical properties and processability as well as control of ion exchange capacity and ion conductivity are very easy and ion conductivity is superior to conventional cation exchange composite membranes.

In addition, since it does not contain expensive olefinic additives used in conventional cation exchange composite membranes, it is economical. The olefinic additives have low reactivity and it is difficult to form a cation exchange composite membrane. In the case of a plasticizer, The plasticizer is uniformly dissolved in the solution uniformly during the preparation of the composite membrane and the plasticizer can be uniformly distributed in the membrane without phase separation even after the polymerization is proceeded and the solution is changed to the solidified composite membrane. It is easy.

In the cation exchange composite membrane according to the present invention, the copolymer may be supported by a support. The support may be selected from any of polymers having a fabric type excellent in mechanical strength and chemical resistance without limitation, and supports such as polyether, polypropylene, polyvinyl chloride and polytetrafluoroethylene may preferably be used.

Further, in the cation exchange composite membrane according to the present invention, the copolymer contains 97 to 90% by weight of a monomer mixture comprising a styrene monomer, a tert-butylstyrene monomer, a crosslinking agent and an initiator, and 3 to 10% By weight, based on the total weight of the composition. When the content of the plasticizer is less than 3% by weight, the effect is not clear and the brittleness is difficult to be improved. When the plasticizer content exceeds 10% by weight, the flexibility of the cation exchange composite membrane is excessively lowered, Lt; / RTI &gt;

Further, in the production of the vinyl benzyl system-styrenic copolymer and the plasticizer-containing material constituting the present invention, as the plasticizer, any general plasticizer used in the molding of a polymer product may be used, but preferably, dioctyl phthalate, Phthalate plasticizers such as naphthalate and dibutyl phthalate, adipates such as dioctyl adipate and diisononyl adipate, and dioctyl malate, etc. may be used alone or in combination.

In addition, in obtaining the substance including the styrene-ter-butylstyrene copolymer and the plasticizer constituting the present invention, the styrene-based monomer is used as the sulfonation-reactive monomer, and the styrene- May be selected and used without limitation. Preferably, styrene, alphamethylstyrene, vinylpyridine, trifluorostyrene, 2-vinylpyridinium and the like can be used alone or in combination, and more preferably, a styrene monomer having sulfonation reaction activity can be used.

In addition, the tert-butylstyrene-based monomer is used as the sulfonation-inactivation monomer in obtaining the substance including the styrene-ter-butylstyrene copolymer and the plasticizer constituting the present invention, and the inert monomer is butylstyrene-based.

The sulfonation-inert tert-butylstyrene monomer inhibits the introduction of the cation exchanger, thereby lowering the ion exchange capacity as the composition thereof increases. However, the water content can be lowered to maintain the strength of the composite membrane. Accordingly, in the cation exchange composite membrane according to the present invention, the ion exchange ability and the ion conductivity of the cation exchange composite membrane can be easily controlled by controlling the composition of the styrene monomer and the tert-butylstyrene monomer.

Further, in obtaining the substance including the styrene-ter-butylstyrene copolymer and the plasticizer constituting the present invention, the plasticizer may be added to the styrene-ter-butylstyrene polymer to increase the flexibility of the film, The plasticizer can be selected and used without limitation. The cation exchange composite membrane of the present invention can exhibit excellent mechanical properties by including a plasticizer.

In addition,

Impregnating a polymeric solution comprising a styrene-based monomer, a tert-butylstyrene-based monomer, a plasticizer, a crosslinking agent and an initiator with a support in the form of a fabric (step 1);

Preparing a composite membrane comprising a cross-linked styrene-ter-butyl styrenic copolymer and a plasticizer by adding a styrene-based monomer, a tert-butyl styrene-based monomer and a plasticizer in a cloth-shaped support impregnated in step 1 above (Step 2); And

(Step 3) of reacting chlorosulfonic acid or sulfuric acid with a composite membrane composed of the styrene-ter-butyl styrenic copolymer and plasticizer of step 2 and introducing a sulfonated group with a cation exchanger to prepare a cation- The present invention also provides a method for producing a cation exchange composite membrane.

Hereinafter, the method for producing the cation exchange composite membrane according to the present invention will be described in detail for each step.

When the plasticizer is mixed with the monomer solution to prepare a composite membrane, the plasticizer must be uniformly dissolved in the solution uniformly. Also, even after the polymerization is proceeded and the solution is changed into a solidified film, It should be uniformly distributed. The plasticizer used in the present invention is very well soluble in the present monomer mixture (styrene, tert-butylstyrene, divinylbenzene) composed of a liquid and can maintain a uniform phase. Even after polymerization and crosslinking, the plasticizer can be homogeneously Is an additive having a high affinity for a styrenic-tert-butyl styrenic copolymer distributed therein.

Therefore, it is economical to use a plasticizer which is easier to manufacture and less expensive than the conventional cation exchange composite membrane.

First, in the method for producing a cation exchange composite membrane according to the present invention, step 1 is a step of impregnating a support in the form of a fabric in a polymerization solution containing a styrene monomer, a tert-butyl styrene monomer, a plasticizer, a crosslinking agent and an initiator.

Specifically, the polymerization solution of Step 1 is prepared by mixing a styrene-based monomer with a tert-butylstyrene-based monomer, a plasticizer, a crosslinking agent and an initiator.

In this case, the polymerization solution of Step 1 is prepared by mixing 97 wt% to 90 wt% of a monomer mixture containing a styrene monomer, a tert-butylstyrene monomer, a crosslinking agent and an initiator and 3 wt% to 10 wt% And the initiator is preferably contained in an amount of 0.1 to 5% by weight based on 100% by weight of the monomer mixture. The styrene-based monomer, the tert-butylstyrene-based monomer and the cross-linking agent in the polymerization solution of Step 1 are preferably mixed at a weight ratio of 2: 4: 5 to 7: 0.5 to 2.0.

Further, although the general plasticizers used in molding the polymer product may be used as the plasticizer in the step 1, phthalate plasticizers such as dioctyl phthalate, diisononyl phthalate and dibutyl phthalate, and dioctyl adipate, diisononyl Adipate such as adipate, and dioctyl maleate may be used alone or in combination.

The crosslinking agent of step 1 plays a role in controlling the degree of swelling and the degree of crosslinking of the final composite membrane. Any crosslinking agent capable of crosslinking the styrene-tert-butyl styrene copolymer can be used without limitation, Benzene can be used.

The initiator of step 1 may be selected without limitation as long as it can initiate thermal crosslinking polymerization. Preferably, N, N'-azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO) Cumyl peroxide, lauroyl peroxide and the like can be used, and more preferred is N, N'-azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO).

Further, the saturated textile type support of step 1 may be prepared by impregnating a support such as polyethylene, polypropylene, polyvinyl chloride, or polytetrafluoroethylene in the form of a fabric in a polymerization solution prepared by mixing a monomer mixture solution with a plasticizer at room temperature . Since the support in the form of a saturated fabric is filled with the polymerization solution and the network structures of the spaces between the fibers are plasticized in the process of processing, the mechanical strength and chemical resistance And a uniform ion exchange membrane can be produced.

Next, in the method for producing a cation exchange composite membrane according to the present invention, Step 2 is a step of adding a styrene-based monomer, a tert-butylstyrene-based monomer and a plasticizer in a cloth-shaped support impregnated in Step 1, tert-butyl styrene copolymer and a plasticizer.

Specifically, the polymerization reaction in Step 2 is preferably carried out for 30 minutes to 24 hours, more preferably 30 minutes to 24 hours, so that the styrene monomer, the tert-butylstyrene monomer, the plasticizer, the crosslinking agent and the initiator can sufficiently reach the equilibrium state , The fabric-type support should be left in the polymerization solution at room temperature for 1 to 12 hours.

Thereafter, the support onto which the polymerized solution is impregnated is placed on a rectangular glass plate, covered with another glass plate, and then subjected to polymerization using heat at a temperature of 50 to 100 DEG C for 8 to 24 hours to form a styrene- a tert-butyl styrene copolymer and a plasticizer can be produced. After the completion of the polymerization reaction, the unreacted monomers remaining in the membrane may be washed in several times in an organic solvent such as tetrahydrofuran, dichloroethane, acetone, toluene or the like.

Next, in the method for producing a cation exchange composite membrane according to the present invention, step 3 is a step of reacting a composite membrane comprising the styrene-ter-butylstyrene copolymer and the plasticizer of step 2 with chlorosulfonic acid or sulfuric acid And introducing a sulfonation group into a cation exchange group to prepare a cation exchange composite membrane.

Specifically, the chlorosulfonic acid or sulfuric acid in step 3 may be diluted with an organic solvent such as dichloroethane, and may be reacted with a copolymer comprising the styrene-ter-butyl styrenic copolymer and the plasticizer of step 2 To introduce a sulfone group. The concentration of chlorosulfonic acid or sulfuric acid in the reaction for introducing a sulfonate group into the copolymer can be used without any great limitation, but it is preferably 0.5% by weight or more for chlorosulfonic acid, 95% by weight or more for sulfuric acid Is preferably used.

The reaction of the styrene-terbutylstyrene-based copolymer containing the plasticizer with chlorosulfonic acid or sulfuric acid is carried out by immersing the copolymer membrane in a mixed solution of dichloroethane and chlorosulfonic acid or a mixed solution of dichloroethane and sulfuric acid, Hour to 24 hours, preferably 1 hour to 2 hours. After the completion of the reaction, the reaction mixture is washed with ultra pure water or organic solvent at room temperature several times to remove unreacted materials remaining in the composite membrane, and then immersed in ultrapure water or organic solvent overnight and then washed several times to prepare a cation exchange complex A membrane can be produced.

The cation exchange membrane according to the present invention is excellent in ion exchange capacity and has a high mechanical strength by using a support having a high strength. In addition, the cation exchange membrane according to the present invention is superior to a cation exchange membrane without a plasticizer , Low brittleness is significantly lowered by having a low water content, the strength is improved, the low membrane area resistance is obtained, the ion conductivity is improved, the flexibility of the membrane is increased, and the ion distribution of the whole membrane is improved. Therefore, the method for producing a cation exchange composite membrane of the present invention can be usefully used in the production of a cation exchange composite membrane having improved ion exchange capacity, mechanical properties, chemical properties, processability and ionic conductivity while having low electric resistance.

Further,

There is provided a composite membrane module comprising a cation exchange composite membrane comprising a sulfonated styrene-based tert-butyl styrene copolymer and a plasticizer represented by the above formula (1).

The composite membrane module comprising a sulfonic group-introduced styrene-tert-butyl styrene copolymer and a cation exchange composite membrane comprising a plasticizer has a low ion exchange capacity, mechanical properties and chemical properties great. In addition, compared with a composite membrane module comprising a conventional cation exchange composite membrane, it is easy to manufacture and is inexpensive.

Further,

The present invention provides a separation and purification process using a composite membrane module comprising a cation exchange membrane comprising a sulfonated styrene-tert-butyl styrene copolymer and a plasticizer represented by the above formula (1) and a plasticizer.

The separation process using the composite membrane module including the cation exchange composite membrane according to the present invention is capable of separating and purifying with high purity as compared with the separation method using distillation or chemical treatment, consuming less energy, And can be used as a separation and purification process in various industrial fields in that the continuous process is possible and the processing ability per hour is excellent.

Particularly, by using a cation exchange composite membrane comprising a sulfonated group-introduced styrene-ter-butyl styrenic copolymer and a plasticizer, it is economical not only in terms of ion exchange ability, mechanical properties and chemical properties, but also inexpensiveness .

Hereinafter, the present invention will be described in more detail with reference to the following Examples and Experimental Examples.

However, the following examples and experimental examples are intended to illustrate the contents of the present invention, but the scope of the invention is not limited by the examples and the experimental examples.

Example 1 Preparation of a cation exchange composite membrane containing a plasticizer-1

Step 1: Polymerization in which styrene: tert-butylstyrene: divinylbenzene was mixed at a weight ratio of 30: 60: 10 and 100 wt% of the monomer mixture was mixed with 1 wt% of benzoyl peroxide (BPO) Was mixed with a plasticizer dioctyl phthalate in a weight ratio of 97: 3 to prepare a polymerization solution. Thereafter, a polyethylene support in the form of a fabric having a thickness of about 180 [mu] m was dipped in the polymerization solution for 4 hours to be saturated impregnated.

Step 2: In step 1, the polyethylene support impregnated with the polymerization solution was placed on a rectangular glass plate, covered with another glass plate, and sealed with a tape to prevent loss of the polymerization solution. The polymerization was carried out in an oven at a temperature of 65 DEG C for 16 hours. After completion of the polymerization, the membrane was separated from the glass plate, immersed in tetrahydrofuran at room temperature, and allowed to stand for 12 hours. Then, the membrane was taken out and immersed in tetrahydrofuran to remove unreacted monomer several times to obtain a styrene-terbutylstyrene- To prepare a composite membrane.

Step 3: The composite membrane prepared in Step 2 was immersed in a mixed solution of 1 volume% of chlorosulfonic acid and 99 volume% of dichloroethane in a volume ratio of 1: 3, and sulfonated at room temperature for 24 hours. After completion of the sulfonation reaction, the reaction mixture was washed several times at room temperature with ultrapure water to remove the unreacted chlorosulfonic acid remaining in the composite membrane, and the membrane was washed several times with ultrapure water overnight, . By this process, a styrene-tert-butylstyrene-based cation exchange composite membrane to which a plasticizer having polyethylene as a support and having a total membrane thickness of about 220 탆 was added was prepared.

&Lt; Example 2 > Preparation of a cation exchange composite membrane containing a plasticizer - 2

Step 1: Polymerization in which styrene: tert-butylstyrene: divinylbenzene was mixed at a weight ratio of 25: 60: 15 and 100 wt% of the monomer mixture was mixed with 1 wt% of benzoyl peroxide (BPO) The solution was mixed with plasticizer dioctyl phthalate in a weight ratio of 95: 5 to prepare a polymerization solution. A polypropylene support in the form of a fabric having a thickness of about 180 [mu] m was then impregnated into the polymerization solution for 3 hours to saturate.

Step 2: In step 1, the polypropylene support impregnated with the polymerization solution was placed on a rectangular glass plate, covered with another glass plate, and sealed with a tape to prevent loss of the polymerization solution. The polymerization was carried out in an oven at a temperature of 65 DEG C for 16 hours. After completion of the polymerization, the membrane was separated from the glass plate, immersed in tetrahydrofuran at room temperature, and allowed to stand for 12 hours. Then, the membrane was taken out and immersed in tetrahydrofuran to remove unreacted monomer several times to obtain a styrene-terbutylstyrene- To prepare a composite membrane.

Step 3: The composite membrane prepared in Step 2 was immersed in a mixed solution of 1 volume% of chlorosulfonic acid and 99 volume% of dichloroethane in a volume ratio of 1: 3, and sulfonated at room temperature for 24 hours. After completion of the sulfonation reaction, the reaction mixture was washed several times at room temperature with ultrapure water to remove the unreacted chlorosulfonic acid remaining in the composite membrane, and the membrane was washed several times with ultrapure water overnight, . By this procedure, a styrene-tert-butylstyrene-based cation exchange composite membrane to which a plasticizer having polypropylene as a support and having a total membrane thickness of about 220 탆 was added was prepared.

< Example  3> Cation exchange with plasticizer Composite membrane  Manufacturing - 3

Step 1: Polymerization in which styrene: tert-butylstyrene: divinylbenzene was mixed at a weight ratio of 25: 60: 15 and 100 wt% of the monomer mixture was mixed with 1 wt% of benzoyl peroxide (BPO) The solution was mixed with a plasticizer dioctyl maleate at a weight ratio of 93: 7 to prepare a polymerization solution. Thereafter, a polyvinyl chloride support in the form of a fabric having a thickness of about 180 [mu] m was immersed in the polymerization solution for 4 hours for saturation impregnation.

Step 2: In step 1, the polyvinyl chloride support impregnated with the polymerization solution was placed on a rectangular glass plate, covered with another glass plate, and sealed with a tape to prevent loss of the polymerization solution. The polymerization was carried out in an oven at a temperature of 80 DEG C for 16 hours. After completion of the polymerization, the membrane was separated from the glass plate, immersed in tetrahydrofuran at room temperature, and allowed to stand for 12 hours. Then, the membrane was taken out and immersed in tetrahydrofuran to remove unreacted monomer several times to obtain a styrene-terbutylstyrene- To prepare a composite membrane.

Step 3: The composite membrane prepared in Step 2 was immersed in a mixed solution of 1 volume% of chlorosulfonic acid and 99 volume% of dichloroethane in a volume ratio of 1: 3, and sulfonated at room temperature for 24 hours. After completion of the sulfonation reaction, the reaction mixture was washed several times at room temperature with ultrapure water to remove the unreacted chlorosulfonic acid remaining in the composite membrane, and the membrane was washed several times with ultrapure water overnight, . By this procedure, a styrene-tert-butylstyrene-based cation exchange composite membrane to which a plasticizer having polypropylene as a support and having a total membrane thickness of about 220 탆 was added was prepared.

< Example  4> Cation exchange with plasticizer Composite membrane  Manufacturing - 4

Step 1: Polymerization in which styrene: tert-butylstyrene: divinylbenzene was mixed at a weight ratio of 25: 60: 15 and 100 wt% of the monomer mixture was mixed with 1 wt% of benzoyl peroxide (BPO) The solution was mixed with a plasticizer dioctyl maleate at a weight ratio of 90: 10 to prepare a polymerization solution. A polytetrafluoroethylene support in the form of a fabric having a thickness of about 180 [mu] m was then dipped in the polymerization solution for 3 hours to saturate.

Step 2: In step 1, the polytetrafluoroethylene support impregnated with the polymerization solution was placed on a rectangular glass plate, covered with another glass plate, and sealed with a tape to prevent loss of the polymerization solution. The polymerization was carried out in an oven at a temperature of 80 DEG C for 16 hours. After completion of the polymerization, the membrane was separated from the glass plate, immersed in tetrahydrofuran at room temperature, and allowed to stand for 12 hours. Then, the membrane was taken out and immersed in tetrahydrofuran to remove unreacted monomer several times to obtain a styrene-terbutylstyrene- To prepare a composite membrane.

Step 3: The composite membrane prepared in Step 2 was immersed in a mixed solution of 1 volume% of chlorosulfonic acid and 99 volume% of dichloroethane in a volume ratio of 1: 3, and sulfonated at room temperature for 24 hours. After completion of the sulfonation reaction, the reaction mixture was washed several times at room temperature with ultrapure water to remove the unreacted chlorosulfonic acid remaining in the composite membrane, and the membrane was washed several times with ultrapure water overnight, . By this procedure, a styrene-tert-butylstyrene-based cation exchange composite membrane to which a plasticizer having polypropylene as a support and having a total membrane thickness of about 220 탆 was added was prepared.

< Comparative Example  1> Cation exchange without plasticizer Composite membrane  Produce

A cation exchange composite membrane was prepared in the same manner as in Example 1 except that no plasticizer was used in the preparation of the polymerization solution in the step 1 of Example 1 above.

< Comparative Example  2> Paste method  &Lt; RTI ID = 0.0 &gt;

(Commercially available from Astrom Corporation, CMX, thickness: about 140 占 퐉) prepared by a conventional paste method commercially available.

< Comparative Example  3> Cation exchange involving olefin additive Composite membrane  Produce

Step 1: Styrene: tert-butylstyrene: divinylbenzene was mixed in a weight ratio of 30: 60: 10, and N, N'-azobisisobutyronitrile (AIBN) By weight, and 1-hexene as an olefin-based additive was mixed at a weight ratio of 50:50 to prepare a polymerization solution. Thereafter, a polyethylene support in the form of a fabric having a thickness of about 180 [mu] m was dipped in the polymerization solution for 4 hours to be saturated impregnated.

Step 2: In step 1, the polyethylene support impregnated with the polymerization solution was placed on a rectangular glass plate, covered with another glass plate, and sealed with a tape to prevent loss of the polymerization solution. The polymerization was carried out in an oven at a temperature of 65 DEG C for 16 hours. After completion of the polymerization, the membrane was separated from the glass plate, immersed in tetrahydrofuran at room temperature, allowed to stand for 12 hours, and then taken out and immersed in tetrahydrofuran to remove unreacted monomers several times to obtain a styrene-tert- Based additive was prepared.

Step 3: The composite membrane prepared in Step 2 was immersed in a mixed solution of 1 volume% of chlorosulfonic acid and 99 volume% of dichloroethane in a volume ratio of 1: 3, and sulfonated at room temperature for 24 hours. After completion of the sulfonation reaction, the reaction mixture was washed several times at room temperature with ultrapure water to remove the unreacted chlorosulfonic acid remaining in the composite membrane, and the membrane was washed several times with ultrapure water overnight, . By this process, a styrene-tert-butylstyrene type cation-exchange composite membrane to which olefin was added with polyethylene as a support, having a membrane total thickness of about 230 탆, was prepared.

< Experimental Example  1> cation Exchange membrane  Character analysis

In order to confirm the improved characteristics of the cation exchange composite membrane comprising the sulfonated styrene-ter-butyl styrenic copolymer and the plasticizer according to the present invention, Examples 1 to 4 and Comparative Examples 1 to 3 The water content, ion exchange capacity (IEC) and membrane area resistance of the cation exchange composite membrane prepared in Example 1 were measured by the following experiment, and the results are shown in Table 1 below.

First, the water content of the cation-exchange composite membrane was measured by immersing the cation-exchange composite membrane in ultrapure water for 24 hours or more to sufficiently swell the membrane, carefully wiping the surface water and measuring the weight W ₁ (g) After drying in a set vacuum oven, the dry weight W ₂ (g) was measured and the water content (%) was calculated by the following equation (1).

&Quot; (1) &quot;

In addition, the ion exchange capacity of the cation exchange composite membrane was measured by measuring the dry weight of the cation exchange composite membrane and then immersing the membrane in a 1.0 M hydrochloric acid (HCl) solution for 5 hours to completely replace the sulfonate group with the -SO ₃ H ⁺ Before the titration, the sulfonate was immersed in a 2.0 M NaCl solution for 5 hours, replaced with -SO ₃ Na ⁺ , and washed with 1 M of sodium chloride Sodium hydroxide (NaOH) solution. The amount of consumed sodium hydroxide (NaOH) was measured, and the ion exchange capacity (IEC, unit meq / g) was calculated by the following formula (2).

&Quot; (2) &quot;

(Where W _y represents the weight of the dried membrane, V represents the amount of consumed sodium hydroxide (NaOH), and C represents the concentration of the sodium hydroxide (NaOH) solution used in the titration).

Further, the membrane area resistance of the cation exchange composite membrane was calculated from the impedance value and the phase angle measured using an LCZ meter in a 0.5 M NaCl aqueous solution by the following equation (3) .

&Quot; (3) &quot;

(In the above equation (3),? Represents a phase angle and Z represents an impedance value).

division

Example Comparative Example Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2
(Commercial membrane, CMX) Comparative Example 3

polymerization
solution
ingredient
(weight%) Plasticizer
(Plasticizer
Kinds) 3
(Dioctyl phthalate) 5
(Dibutyl phthalate) 7
(Dioctyl maleate) 10
(Dioctyl maleate) - - 100
(1-hexene) textile
Support Poly
Ethylene Poly
Propylene Polyvinyl chloride Polytetrafluorene ethylene Poly
Ethylene - Poly
Ethylene Styrene 30 25 25 25 30 - 30 tert-
Butyl styrene 60 60 60 60 60 - 60 Divinylbenzene 10 15 15 15 10 - 10


Properties
Ion exchange
Volume
(meq./g) 3.8 3.7 3.6 3.5 3.7 2.4 3.5 Moisture content
(%) 21 19 17 13 46 25 28 Membrane area
resistance
(Ω · cm ² ) 1.6 1.8 2.1 2.3 3.8 3.5 2.5

As shown in Table 1 above, the cation exchange composite membranes of Examples 1 to 4, in which a plasticizer was used for the preparation of the polymerization solution, were compared with Comparative Example 1 in which no plasticizer was used, Comparative Example 2 in which a commercial membrane was used, As a result of mutual comparison with Example 3,

The cation exchange composite membranes of Examples 1 to 4 of the present invention had a lower water content than the membranes of Comparative Example 1 and Comparative Example 2 by using a support having a high strength in the form of a fabric and containing a plasticizer to lower the brittleness, It was found that the ion conductivity was improved by the lowering of the ion conductivity. In addition, it was confirmed that even when compared with the cation exchange composite membrane of Comparative Example 3 containing the conventional olefin-based additive, it exhibited a low water content and a low membrane area resistance.

The ion exchange capacity of the composite membrane is increased because the ion exchange capacity of the cation exchange membrane is increased, that is, the higher the ion exchange capacity is, the higher the ion exchange ability is. However, the higher the ion exchange capacity, the higher the swelling degree of the composite membrane, and the mechanical properties of the composite membrane are lowered. Therefore, a method capable of suppressing the degree of water swelling while maintaining a high ion exchange capacity is important. In the present invention, by adding a hydrophobic plasticizer, the effect of suppressing the degree of water swelling is maintained while maintaining the ion exchange ability.

Furthermore, the cation exchange composite membranes of Examples 1 to 4 of the present invention have a low membrane area resistance, which not only improves the ion conductivity but also increases the flexibility of the membrane, thereby improving the ion distribution of the whole membrane, can confirm. The thickness of the cation exchange composite membranes of Examples 1 to 4 is 220 탆, which is much thicker than the thickness of the commercial membrane CMX of Comparative Example 2, which is about 140 탆, . In particular, it was confirmed that the composite membrane of Comparative Example 3 containing an olefin-based additive had a low membrane area resistance and an excellent ion conductivity.

Therefore, the cation exchange membrane composite membrane comprising the sulfonated group-containing styrene type-tert-butyl styrene type copolymer and the plasticizer of the present invention has low ion exchange capacity, mechanical properties, chemical properties, processability and ion conductivity Is an improved cation exchange composite membrane. It is economical to use a cheap plasticizer at a low cost, and a method of producing the same is easy, so that it can be easily used in the production of a cation exchange composite membrane.

Claims (10)

1. A cation exchange composite membrane comprising a sulfonated styrene-tert-butyl styrene copolymer and a plasticizer represented by the following formula (1), wherein the cation exchange membrane is a non-nitric rubber-

&Lt; Formula 1 >

(In the formula 1,
"

Quot; represents a random copolymer).
The method according to claim 1,
Wherein the plasticizer is at least one selected from the group consisting of dioctyl phthalate, diisononyl phthalate, dibutyl phthalate, dioctyl adipate, diisononyl adipate and dioctyl malate.
The method according to claim 1,
Characterized in that the copolymer is obtained by copolymerizing from 97% by weight to 90% by weight of a monomer mixture comprising a styrene-based monomer, a tert-butylstyrene-based monomer, a crosslinking agent and an initiator and from 3% by weight to 10% by weight of a plasticizer. Composite membrane.
The method of claim 3,
Wherein the styrene monomer is one or a mixture of two or more selected from the group consisting of alpha methyl styrene, vinyl pyridine, trifluorostyrene, and 2-vinyl pyridinium.
Impregnating a polymeric solution comprising a styrene-based monomer, a tert-butylstyrene-based monomer, a plasticizer, a crosslinking agent and an initiator with a support in the form of a fabric (step 1);
Preparing a composite membrane comprising a cross-linked styrene-ter-butyl styrenic copolymer and a plasticizer by adding a styrene-based monomer, a tert-butyl styrene-based monomer and a plasticizer in a cloth-shaped support impregnated in step 1 above (Step 2); And
(Step 3) of reacting chlorosulfonic acid or sulfuric acid with a composite membrane composed of the styrene-ter-butyl styrenic copolymer and plasticizer of step 2 and introducing a sulfonated group with a cation exchanger to prepare a cation- &Lt; / RTI &gt; of claim 1.
6. The method of claim 5,
Wherein the polymerization solution of step 1 is a mixture of 97 wt% to 90 wt% of a monomer mixture comprising a styrene monomer, a tert-butyl styrene monomer, a crosslinking agent and an initiator, and 3 wt% to 10 wt% Exchange composite membrane.
6. The method of claim 5,
Wherein the styrene-based monomer, the tert-butylstyrene-based monomer, and the cross-linking agent in the polymerization solution of Step 1 are mixed at a weight ratio of 2: 4: 5 - 7: 0.5 - 2.0.
6. The method of claim 5,
Wherein the crosslinking agent of step 1 is divinylbenzene.
1. A composite membrane module comprising a cation exchange membrane composite membrane according to claim 1 comprising a sulfonated styrene-based tertiary-butyl styrene copolymer represented by the following formula (1) and a plasticizer:

&Lt; Formula 1 >

(In the formula 1,
"

Quot; represents a random copolymer).
A process for separating and purifying a composite membrane module comprising the cation exchange membrane composite membrane according to claim 1, comprising a sulfonated styrene-tert-butyl styrene copolymer represented by the following formula (1) and a plasticizer:

&Lt; Formula 1 >

(In the formula 1,
"

Quot; represents a random copolymer).