KR102191140B1 - An ion-exchange membrane and a method for manufacturing the same - Google Patents

Abstract

An embodiment of the present invention is a matrix comprising a polyolefin having a weight average molecular weight (Mw) of 250,000 to 450,000; And it provides a silane-modified polyolefin crosslinked in the matrix; including a support and an electrolyte, an ion exchange membrane and a method of manufacturing the same.

Description

Ion exchange membrane and its manufacturing method {AN ION-EXCHANGE MEMBRANE AND A METHOD FOR MANUFACTURING THE SAME}

The present invention relates to an ion exchange membrane and a method of manufacturing the same.

Ion exchange membranes are used in various fields such as fuel cells, redox flow cells, water treatment, and seawater desalination. Ion exchange membranes are attracting worldwide attention as a major clean technology capable of reducing environmental pollution by reducing the use of fossil raw materials, especially because of their relatively simple manufacturing process, excellent selectivity for specific ions, and a wide range of applications. The ion exchange membrane as described above can selectively separate cations and anions in aqueous solutions, such as fuel cells, electrodialysis, water decomposition electrodialysis for recovering acids and bases, diffusion dialysis for recovering acids and metal species from pickling waste, ultrapure water. It is widely used, such as a process, and as high-performance ion exchange membranes have recently been developed in advanced countries, their application range is further expanded.

Such an ion exchange membrane should have high selectivity and require low permeability of solvent and non-ionic solutes, low resistance to diffusion of selected permeated ions, high mechanical strength and chemical resistance. These ion exchange membranes are required to have excellent mechanical strength and durability. Methods commonly used to meet these needs include a method of preparing a hybrid composite membrane by adding an inorganic substance, a hot press method of heat-pressing a catalyst mixture, a method of adding a curing agent, and the like. The hybrid composite membrane manufacturing method has a disadvantage in that if the swelling phenomenon of the membrane continues, a gap is created between the additive of the membrane and the polymer membrane, so that normal ion exchange capability cannot be exhibited. In addition, the method of adding the curing agent also has a disadvantage in that the curing agent is eluted over time. Due to the above-described problems, the development of an ion exchange membrane having high durability and excellent mechanical properties is still required.

Currently, commercially available ion exchange membranes include sulfonated polystyrene, Nafion ^™ (hereinafter referred to as "Nafion") manufactured by Du Pont. However, when the sulfonated polystyrene is dried, it is broken due to an increase in brittleness, making it difficult to form a thin film or a composite film, and there is a disadvantage in that mechanical stability is lowered when processed into an electrode. In order to improve these disadvantages, there is a method of adjusting the sulfonation ratio of polystyrene or a method of increasing the thickness of the membrane.In this case, the resistance of the membrane is increased and the ion exchange capacity of the membrane is remarkably decreased, and the performance as an ion exchange membrane cannot be expected. When the system is manufactured, the volume is increased and space is limited. In addition, Nafion, as a fluorine-based material, has been widely used as an ion exchange membrane due to its high ion conductivity and chemical stability. However, due to the fluorine compound, it is very expensive and its use at high temperatures is limited. In fact, expensive ion exchange membranes such as Nafion have been pointed out as a cause of increasing the cost of manufacturing the stack. The unit cost of a fluorine-based ion exchange membrane such as Nafion is about 1 million won/m ² , which is one of the problems to be solved. Accordingly, various studies have been conducted on non-fluorine ion exchange membranes with low cost, in particular, SPAES (sulfonated poly arylene ether sulfone), SPEEK (sulfonated polyether ether ketone), PBI (polybenzimidazole), SPSf (sulfonated polysulfone), and other synthetic polymers. Studies on hydrocarbon-based polymers have been extensively conducted.

As described above, new materials have been developed and tested for their possibilities by controlling various factors such as the introduction of various functional groups into the non-fluorine-based polymer, the arrangement of the polymer chain, and the control of the molecular weight. However, most materials are limited in practical application due to low chemical and physical stability compared to their excellent electrical performance.

On the other hand, although various methods have been suggested to improve the performance of the polymer material itself, there is still a problem of low ion selectivity and durability.

The present invention is to solve the problems of the prior art described above, the object of the present invention is excellent in mechanical properties and ion exchange ability, it can be implemented uniformly, and the production cost increases according to the elution and disposal of alkoxyvinylsilane. To solve the problem, to provide an ion exchange membrane with excellent economical efficiency and a manufacturing method thereof.

One aspect of the present invention, a weight average molecular weight (M _w ) a matrix comprising a polyolefin having a weight average molecular weight (M _w ) of 250,000 to 450,000, and a porous support comprising a crosslinked silane-modified polyolefin in the matrix; And an electrolyte impregnated in the pores of the porous support or applied to the surface thereof.

In one embodiment, the porous support may further include an inorganic filler.

In one embodiment, the content of the inorganic filler in the porous support may be 10 to 70% by weight.

In one embodiment, the content of the silane-modified polyolefin in the porous support may be 0.1 to 5% by weight.

In one embodiment, the silane may be a vinyl silane containing an alkoxy group.

In one embodiment, the porous support may satisfy one or more of the following conditions (i) to (ix).

(i) air permeability 125~300sec/100ml; (ii) punching strength 200~400gf; (iii) Tensile strength in the longitudinal direction (MD) 1,500~3,000kgf/cm ² ; (iv) Transverse direction (TD) tensile strength 1,000~2,500kgf/cm ² ; (v) 80% or less of tensile elongation in the longitudinal direction (MD); (vi) 55% or less of tensile elongation in the transverse direction (TD); (vii) 10% or less of longitudinal heat shrinkage at 120°C; (viii) 15% or less in transverse direction heat shrinkage at 120°C; (ix) Meltdown temperature 200~250℃.

In one embodiment, the average pore size of the porous support may be 20 ~ 2,000nm.

In one embodiment, the porous support may have a contact angle of 15° or less.

In one embodiment, the porosity of the porous support may be 30 to 90%.

In one embodiment, the electrolyte may include a sulfonated polymer, a fluorine-based compound, or a combination thereof.

In one embodiment, the degree of sulfonation of the sulfonated polymer may be 60 to 90%.

In one embodiment, the sulfonated polymer is polysulfone series, poly(ethersulfone) series, poly(thiosulfone) series, poly(etheretherketone) series, polyimide series, polystyrene series, polyphosphagen series, and It may be one sulfonated hydrocarbon-based polymer selected from the group consisting of a mixture of two or more of these.

In one embodiment, the fluorine-based compound is a copolymer of tetrafluoroethylene and fluorovinyl ether containing perfluorosulfonic acid, poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), sulfonic acid group, It may be one selected from the group consisting of polytetrafluoroethylene, polyvinylfluoride, polyvinylidene fluoride, polyhexafluoropropylene, and two or more copolymers or combinations thereof.

Another aspect of the present invention, (a) manufacturing a porous support by processing a composition comprising a polyolefin having a weight average molecular weight (M _w ) of 250,000 to 450,000 and a silane-modified polyolefin; (b) crosslinking the silane-modified polyolefin contained in the porous support; And (c) impregnating the porous support in an electrolyte solution containing an electrolyte and a solvent; containing, it provides a method for producing an ion exchange membrane.

In one embodiment, the composition may further include a crosslinking catalyst.

In one embodiment, the content of the crosslinking catalyst in the composition may be 0.01 to 5% by weight.

In one embodiment, in the step (b), the porous support may be introduced into a crosslinking tank in which a solution having a boiling point exceeding 100° C. is supported and passed continuously.

In one embodiment, step (b) may be performed at a temperature of 120°C or higher.

In one embodiment, the solution may further include a crosslinking catalyst.

In one embodiment, the content of the crosslinking catalyst in the solution may be 0.5 to 15% by weight.

In one embodiment, prior to step (c), the step of plasma treatment of the porous support in the presence of a mixed gas containing sulfur dioxide (SO ₂ ) and oxygen (O ₂ ); may further include.

In one embodiment, the mixed gas may contain 50 to 90 vol% of sulfur dioxide and 10 to 50 vol% of oxygen.

In one embodiment, the plasma treatment may be performed for 0.5 to 90 minutes.

In one embodiment, the content of the electrolyte in the electrolyte may be 10 to 60% by weight.

The ion exchange membrane and its manufacturing method according to an aspect of the present invention, in the manufacture of the support of the ion exchange membrane, use a polyolefin having silane modification completed without separately performing a silane modification reaction of the polyolefin, which is a weight average molecular weight in a certain range. By mixing and using a polyolefin having a certain ratio with excellent mechanical properties, it can be implemented uniformly, and productivity and economics can be maximized by solving the problem of increasing the manufacturing cost according to the elution and disposal of alkoxyvinylsilane.

According to another aspect of the present invention, by treating the support of the ion exchange membrane with plasma in the presence of a mixed gas containing sulfur dioxide (SO ₂ ) and oxygen (O ₂ ), the surface of the support and the surfaces of the internal pores are hydrophilized and sulfonated. It is possible to improve the binding force with the electrolyte impregnated in the support and thus durability and ion conductivity of the ion exchange membrane.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a scanning electron microscope (SEM) photograph of a porous support manufactured according to an embodiment of the present invention.
2 is a cross-sectional SEM photograph of an ion exchange membrane manufactured according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be implemented in various different forms, and therefore is not limited to the embodiments described herein.

Throughout the specification, when a part is said to be "connected" to another part, this includes not only "directly connected" but also "indirectly connected" with another member interposed therebetween. . In addition, when a part "includes" a certain component, it means that other components may be further provided, rather than excluding other components unless specifically stated to the contrary.

Ion exchange membrane

One aspect of the present invention, a matrix comprising a polyolefin having a weight average molecular weight (Mw) of 250,000 to 450,000 and a porous support comprising a crosslinked silane-modified polyolefin in the matrix; And an electrolyte impregnated in the pores of the porous support or applied to the surface thereof.

The support may be a kind of porous membrane having pores formed therein. The electrolyte may be impregnated in at least a portion of the pores inside the support, and may be further coated on at least a portion of the surface of the support. The electrolyte inside the pores and the electrolyte on the surface of the support may be interconnected.

In the support, the silane-modified polyolefin is crosslinked in the matrix to firmly support and fix the matrix, thereby improving the mechanical properties of the support. As used herein, the term "matrix" refers to a component constituting a continuous phase in a support comprising two or more components. That is, in the support, a polyolefin having a weight average molecular weight (M _w ) of 250,000 to 450,000 may exist in a continuous phase, and a silane-modified polyolefin crosslinked therein may exist in a discontinuous phase.

For practical use of the ion exchange membrane of the present invention, it is necessary to uniformly control the distribution of the silane-modified polyolefin so that the crosslinked silane-modified polyolefin is uniformly distributed in the support. When the crosslinking reaction of the silane-modified polyolefin occurs due to bias in some regions of the support, the required level of mechanical properties cannot be realized, and in particular, the mechanical properties of the support region increase, so the reliability and reproducibility of the product significantly decrease. Can be.

According to an embodiment of the present invention, by adjusting the molecular weight of the polyolefin constituting the matrix to a certain range, the silane-modified polyolefin is uniformly mixed in the polyolefin while the polyolefin and the silane-modified polyolefin are kneaded in an extruder. Can be dispersed. The weight average molecular weight (M _w ) of the polyolefin may be 250,000 to 450,000. If the weight average molecular weight of the polyolefin is more than 450,000, the viscosity increases and processability may be reduced, and if it is less than 250,000, the viscosity is excessively lowered and the dispersibility of the silane-modified polyolefin is extremely reduced, and in some cases, the polyolefin and the silane Phase separation or layer separation may occur between the modified polyolefins.

The polyolefin may be one selected from the group consisting of polyethylene, polypropylene, ethylene vinyl acetate, ethylene butyl acrylate, ethylene ethyl acrylate, and combinations or copolymers of two or more of them, and preferably, polyethylene. It is not limited.

The content of the silane-modified polyolefin in the support may be 0.1 to 5% by weight. If the content of the silane-modified polyolefin in the support is less than 0.1% by weight, the required level of mechanical properties cannot be realized, and if it exceeds 5% by weight, the mechanical properties converge to the required level, which is disadvantageous in terms of economy and productivity.

The silane may be a vinyl silane containing an alkoxy group. For example, the vinylsilane containing an alkoxy group may be one selected from the group consisting of trimethoxyvinylsilane, triethoxyvinylsilane, triacetoxyvinylsilane, and a combination of two or more of them, and preferably, It may be methoxyvinylsilane, but is not limited thereto.

The support may further include an inorganic filler. The inorganic filler is a group consisting of silica (SiO ₂ ), TiO ₂ , Al ₂ O ₃ , zeolite, AlOOH, BaTiO ₂ , talc (Talk), Al (OH) ₃ , CaCO ₃ and a mixture of two or more of them It may be one selected from, preferably spherical nanoparticles having an average particle size of 10 nm to 1,000 nm, preferably nanoparticles whose surface is hydrophobicized or hydrophilized. The content of the inorganic filler in the support may be 10 to 70% by weight, preferably 10 to 60% by weight. If the content of the inorganic filler is less than 10% by weight, mechanical strength, acid resistance, chemical resistance, and flame retardancy of the support may be deteriorated, and if it exceeds 70% by weight, flexibility and workability of the support may be lowered.

For example, silica (SiO ₂ ) may have a hydrocarbon layer formed of hydrophobic linear hydrocarbon molecules formed on its surface. Since silica itself has hydrophilic properties, in order to improve compatibility with hydrophobic polyethylene, a spherical silica nanoparticle coated with a straight-chain hydrocarbon molecule, for example, (poly)ethylene, is suitable.

As described above, the support having a structure in which a certain amount of silane-modified polyolefin is crosslinked in a polyolefin-based matrix whose molecular weight is adjusted to a certain range may satisfy one or more of the following conditions (i) to (ix). (i) air permeability 125~300sec/100ml; (ii) punching strength 200~400gf; (iii) Tensile strength in the longitudinal direction (MD) 1,500~3,000kgf/cm ² ; (iv) Transverse direction (TD) tensile strength 1,000~2,500kgf/cm ² ; (v) 80% or less of tensile elongation in the longitudinal direction (MD); (vi) 55% or less of tensile elongation in the transverse direction (TD); (vii) 10% or less of longitudinal heat shrinkage at 120°C; (viii) 15% or less in transverse direction heat shrinkage at 120°C; (ix) Meltdown temperature 200~250℃.

The support may be hydrophilized and sulfonated to satisfy excellent ionic conductivity. The average pore size of the hydrophilized support may be 20 to 2,000 nm, the contact angle with moisture (H ₂ O) may be 15 degrees or less, and the zeta potential measured as a negative value (-) on the surface of the porous membrane The absolute value of may be 10 mV or more, preferably 15 mV or more, more preferably 20 mV or more. In addition, the porosity of the support may be 30 to 90%, preferably, 50 to 80%.

The hydrophilized support can be easily combined with the electrolyte due to high affinity with the electrolyte, which is essentially hydrophilic, since the -SO ₃ groups generated on the surface and the surface of the inner pores have hydrophilicity. In addition, since the bonding strength can be strengthened, the durability of the ion exchange membrane can be remarkably improved, and since the loss of hydrophilic groups included in the support and the electrolyte is minimized, ion conductivity can also be improved.

The electrolyte may include a sulfonated polymer, a fluorine-based compound, or a combination thereof.

The degree of sulfonation of the sulfonated polymer may be 60 to 90%. As used herein, the term "degree of sulfonation" refers to the total number of moles of a plurality of monomers constituting the sulfonated polymer, m, and the number of moles of a monomer substituted with at least one sulfonic acid group in the sulfonated polymer, n In this case, it can be calculated by the formula n/m. For example, if n/m is 1, the degree of sulfonation may be 100%.

In general, as the degree of sulfonation of the polymer electrolyte increases, the ionic conductivity of the polymer increases, while the hydrophilicity becomes excessively high, resulting in a phenomenon in which it is dissolved in water or severely swelled. Conversely, when the degree of sulfonation is low, the hydrophobicity is strong, so that the water resistance and durability are improved, while there is a problem that the ion conductivity is decreased. Therefore, by adjusting the sulfonation degree of the polymer electrolyte in the range of 60 to 90%, ion conductivity, water resistance, and durability can be achieved in a balanced manner.

The sulfonated polymer is, for example, polysulfone series, poly(ethersulfone) series, poly(thiosulfone) series, poly(etheretherketone) series, polyimide series, polystyrene series, polyphosphazene series, and these Among them, it may be one sulfonated hydrocarbon-based polymer selected from the group consisting of a mixture of two or more, and preferably, may be a sulfonated polysulfone, but is not limited thereto.

The fluorine-based compound is, for example, perfluorosulfonic acid, poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), a copolymer of tetrafluoroethylene containing a sulfonic acid group and fluorovinyl ether, poly It may be one selected from the group consisting of tetrafluoroethylene, polyvinylfluoride, polyvinylidene fluoride, polyhexafluoropropylene, and copolymers or combinations of two or more of them, and preferably, perfluorosulfonic acid. However, it is not limited thereto.

Method of manufacturing an ion exchange membrane

Another aspect of the present invention, (a) manufacturing a porous support by processing a composition comprising a polyolefin having a weight average molecular weight (M _w ) of 250,000 to 450,000 and a silane-modified polyolefin; (b) crosslinking the silane-modified polyolefin contained in the porous support; And (c) impregnating the porous support in an electrolyte solution containing an electrolyte and a solvent; containing, it provides a method for producing an ion exchange membrane.

In the step (a), a composition containing a polyolefin having a weight average molecular weight (M _w ) of 250,000 to 450,000 and a silane-modified polyolefin is introduced into an extruder, extruded, discharged through a T-die, and molded into a sheet, and then stretched. Thus, a porous support can be prepared.

The polyolefin may be one selected from the group consisting of polyethylene, polypropylene, ethylene vinyl acetate, ethylene butyl acrylate, ethylene ethyl acrylate, and combinations or copolymers of two or more of them, and preferably, polyethylene. It is not limited.

The composition may include 20 to 40 parts by weight of the polyolefin and 0.1 to 10 parts by weight of the silane-modified polyolefin. If the content of the silane-modified polyolefin in the composition is less than 0.1 parts by weight, the required level of mechanical properties cannot be realized, and if it exceeds 10 parts by weight, the mechanical properties converge to the required level, which is disadvantageous in terms of economy and productivity.

The silane may be a vinyl silane containing an alkoxy group. For example, the vinylsilane containing an alkoxy group may be one selected from the group consisting of trimethoxyvinylsilane, triethoxyvinylsilane, triacetoxyvinylsilane, and a combination of two or more of them, and preferably, It may be methoxyvinylsilane, but is not limited thereto.

The composition may further include 60 to 80 parts by weight of a pore-forming agent. The pore-forming agent may be extracted and removed from the inside of the support by a wet method using thermally induced phase separation to form pores.

The wet method may be to immerse the support including the pore-forming agent in an extraction tank in which a solvent is supported. The extraction temperature may be 15 to 80°C, preferably, 25 to 40°C, and the extraction time may be 0.1 to 60 minutes, preferably 1 to 20 minutes.

The pore-forming agent is, for example, paraffin oil, paraffin wax, mineral oil, solid paraffin, soybean oil, rapeseed oil, palm oil, palm oil, di-2-ethylhexylphthalate, dibutylphthalate, diisononylphthalate, diisodecylphthalate , Bis(2-propylheptyl)phthalate, naphthenic oil, and may be one selected from the group consisting of a combination of two or more of them, preferably, may be paraffin oil, more preferably, the kinematic viscosity at 40 ℃ 50 ~ It may be 100 cSt paraffin oil, but is not limited thereto.

The solvent for extracting the pore-forming agent may be one selected from the group consisting of pentane, hexane, benzene, dichloromethane, carbon tetrachloride, methyl ethyl ketone, acetone, and a mixture of two or more thereof, preferably dichloromethane. However, it is not limited thereto.

The composition may further include a crosslinking catalyst. If the composition further includes a crosslinking catalyst, the crosslinking reaction in step (b) may be accelerated. As such a crosslinking catalyst, in general, carboxylate, organic bases, inorganic acids and organic acids of metals such as tin, zinc, iron, lead, and cobalt may be used. For example, the crosslinking catalyst is dibutyltindilaurate, dibutyltindiacetate, stannous acetate, stannous caprylic acid, zinc naphthenate, zinc caprylate, cobalt naphthenate, ethylamine, dibutylamine , Hexylamine, pyridine, sulfuric acid, inorganic acids such as hydrochloric acid, toluene sulfonic acid, acetic acid, stearic acid, may be an organic acid such as stearic acid, maleic acid, and the like, and preferably, dibutyltin dilaurate, but is not limited thereto.

The crosslinking catalyst has been conventionally used in the manufacture of a silane-modified polyolefin, or by applying a solution or dispersion of a crosslinking catalyst to a support. However, it is difficult to uniformly disperse the crosslinking catalyst together with the silane-modified polyolefin by such a conventional method. As described above, before crosslinking, the silane-modified polyolefin contained in the support needs to be uniformly dispersed, and at this time, the crosslinking catalyst involved in the crosslinking reaction of the silane-modified polyolefin needs to be uniformly dispersed.

In contrast, by premixing the crosslinking catalyst with a pore former and introducing it through a side feeder of the extruder, the crosslinking catalyst can be uniformly dispersed with the silane-modified polyolefin to further increase the efficiency of the crosslinking reaction.

The content of the crosslinking catalyst in the composition may be 0.01 to 5% by weight. If the content of the crosslinking catalyst is less than 0.01% by weight, the crosslinking reaction cannot be promoted to a required level, and if it exceeds 5% by weight, the reaction rate converges to the required level, which is disadvantageous in terms of economy and productivity.

The stretching performed in step (a) may be performed by a known method such as uniaxial stretching or biaxial stretching (sequential or simultaneous biaxial stretching). In the case of sequential biaxial stretching, the draw ratio may be 4 to 20 times in the horizontal direction (MD) and the vertical direction (TD), respectively, and the surface magnification accordingly may be 16 to 400 times.

In the step (b), the silane-modified polyolefin included in the support may be crosslinked. The crosslinking may be achieved by placing the support in a thermo-hygrostat in which temperature and humidity are controlled within a certain range, and in this case, the step (b) is discontinuous or continuous with the step (a), even if the temperature is constant. Since it is performed in a moisture environment that is difficult to increase above the level, an excessive time may be required for the crosslinking reaction. On the other hand, in the step (b), by introducing the porous membrane into a crosslinking tank in which a solution having a boiling point of more than 100°C, preferably 120°C or more, more preferably 150°C or more is supported and continuously passing through it, the crosslinking reaction It is possible to improve productivity by significantly shortening the time required for operation.

Specifically, since the solution contains a component having a boiling point of more than 100°C, a temperature condition during the crosslinking reaction may be set to more than 100°C, preferably, more than 120°C to promote the crosslinking reaction. As the component, one selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and combinations of two or more of them may be used. These components are hygroscopic and may cause a crosslinking reaction with moisture contained in the components, but if necessary, a certain amount of water may be mixed and used.

In addition, the solution may further include a crosslinking catalyst, and in this case, the crosslinking reaction may be sufficiently promoted even if a certain amount of water is not mixed. The content of the crosslinking catalyst in the solution may be 0.5 to 15% by weight. If the content of the crosslinking catalyst is less than 0.5% by weight, the crosslinking reaction cannot be promoted to the required level, and if it exceeds 15% by weight, the reaction rate converges to the required level, which is disadvantageous in terms of economy and productivity.

The crosslinking catalyst contained in the solution supported in the crosslinking tank has an effect essentially similar to that contained in the composition. However, the crosslinking catalyst included in the composition, that is, the crosslinking catalyst introduced through the side feeder of the extruder in step (a), effectively disperses the silane-modified polyolefin distributed in the center (center layer) of the support in step (b). While crosslinking can be performed, it is difficult to actively participate in the crosslinking reaction of the silane-modified polyolefin distributed in the surface portion (skin layer). The crosslinking catalyst contained in the solution supported in the crosslinking tank is in contact with the surface portion (skin layer) of the support when the support passes through the crosslinking tank, so that the silane-modified polyolefin distributed on the surface portion (skin layer) of the supporter It can further accelerate the crosslinking reaction of. The types and effects of the crosslinking catalyst are as described above.

Prior to the step (c), the step of plasma treating the support in the presence of a mixed gas containing sulfur dioxide (SO ₂ ) and oxygen (O ₂ ); may further include.

When manufacturing an ion exchange membrane to be described later through the plasma treatment, the surface of the support and the surfaces of the internal pores are hydrophilized, that is, the surfaces of the support and the surfaces of the internal pores have a negative charge, thereby improving the bonding strength with the electrolyte. In this way, the durability of the ion exchange membrane, particularly, long-term durability and ion conductivity can be remarkably improved.

Conventionally, in order to hydrophilize the surface of the support and realize a certain level of ionic conductivity, a wet process in which the support is immersed in sulfuric acid for a certain period of time to sulfonate was mainly used, but in this case, the wet process was preceded by plasma treatment or Since it is performed separately from the plasma treatment, such as following, the process is complicated, and there is a problem that a large amount of process waste liquid is generated.

On the other hand, since the process gas used in the plasma treatment contains a certain amount of sulfur dioxide gas as well as conventional air, oxygen and/or inert gas, the plasma treatment is a single plasma treatment without a wet process such as immersing the support in sulfuric acid. Through a dry process, a functional group such as -SO ₃ is generated on the surface of the support and the surface of the internal pores, that is, sulfonated to maximize the hydrophilicity and ionic conductivity of the support, and a conventional complex process Can be simplified and is advantageous in terms of environment.

The mixed gas, which is a process gas used in the plasma treatment, is 50 to 90% by volume of sulfur dioxide and 10 to 50% by volume of oxygen, preferably, 60 to 80% by volume of sulfur dioxide and 20 to 40% by volume of oxygen, more preferably, It may contain 70 to 80 vol% of sulfur dioxide and 20 to 30 vol% of oxygen. If the content of sulfur dioxide in the mixed gas is less than 50% by volume, the level of hydrophilicity required for the support cannot be achieved, and if it exceeds 90% by volume, the process may become unstable.

The plasma treatment may be performed for 0.5 to 90 minutes, preferably, 0.5 to 20 minutes. If the plasma treatment is performed for less than 0.5 minutes, the support cannot be hydrophilized or sulfonated to a required level, and if the plasma treatment is performed for more than 90 minutes, the hydrophilicity and sulfonation degree converge to a certain level, resulting in a decrease in process efficiency.

In the step (c), the support may be impregnated and/or coated with an electrolyte solution containing an electrolyte and a solvent to fill the pores of the support, and if necessary, the electrolyte may have a certain thickness on the surface of the support. Can be coated with. According to the step (c), the thickness of the ion exchange membrane on which the electrolyte is filled and/or coated may be 30 to 200 μm.

The impregnation and/or coating includes (i) a method of impregnating the hydrophilized support into an impregnation bath filled with the electrolyte for a predetermined period of time, (ii) a coating device for transferring the hydrophilized support to the electrolyte, for example For example, it may be coated with a roll coater, a bar coater, or the like, or a combination of (i) and (ii).

In particular, when the step (c) is performed by using a roll coater among the (ii), the roll coater includes a first roll that transfers the electrolyte to one surface of the hydrophilized support and the hydrophilized support. A suction means of a predetermined structure and shape is mounted therein while contacting the other surface to support and transport the support so that the electrolyte delivered from the first roll can be smoothly filled into the pores of the support without empty space. It may include a second roll. In addition, the electrolyte delivered in excess of the amount required for coating is sucked by the suction means mounted inside the second roll and then transferred to a means for supplying the electrolyte to the first roll so that the electrolyte is reused. can do.

The content of the electrolyte in the electrolyte may be 10 to 60% by weight. If the content of the polymer electrolyte is less than 10% by weight, the ion conductivity of the ion exchange membrane may be deteriorated, and if the content of the polymer electrolyte is more than 60% by weight, the ion conductivity is no longer improved, and thus unnecessary raw materials are exhausted, which is disadvantageous in terms of economy.

The electrolyte may include a sulfonated polymer, a fluorine-based compound, or a combination thereof.

The properties of the sulfonated polymer and the fluorine-based compound are as described above.

The solvent of the electrolyte solution may be one selected from the group consisting of ester-based, ether-based, alcohol-based, ketone-based, amide-based, sulfone-based, carbonate-based, aliphatic hydrocarbon-based, aromatic hydrocarbon-based, and mixtures of two or more thereof, Preferably, it may be an amide-based solvent, more preferably N-methyl-2-pyrrolidone.

Examples of the ester solvent include methyl acetate, ethyl acetate, n-butyl acetate, cellosolve acetate, propylene glycol monomethyl acetate, 3-methoxybutyl acetate, methyl butyrate, ethyl butyrate, and propyl propionate. However, it is not limited thereto.

The ether solvents include diethyl ether, dipropyl ether, dibutyl ether, butyl ethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, octyl ether, hexyl ether, etc. However, it is not limited thereto.

Examples of the alcohol-based solvent include methanol, ethanol, propanol, isopropanol, n-butanol, amyl alcohol, cyclohexanol, octyl alcohol, and decanol, but are not limited thereto.

Examples of the ketone-based solvent include acetone, cyclohexanone, methyl amyl ketone, diisobutyl ketone, methyl ethyl ketone, and methyl isobutyl ketone, but are not limited thereto.

Examples of the amide-based solvent include N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methylformamide, dimethylformamide, and dimethylacetamide, but are not limited thereto.

Examples of the sulfone-based solvent include dimethyl sulfoxide, diethyl sulfoxide, diethyl sulfone, tetramethylene sulfone, and the like, but are not limited thereto.

Examples of the carbonate-based solvent include ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, propylene carbonate, ethylene carbonate, and dibutyl carbonate, but are not limited thereto.

Examples of the aliphatic hydrocarbon-based solvent include pentane, hexane, heptane, octane, nonane, decane, dodecane, tetradecane, hexadecane, and the like, and the aromatic hydrocarbon-based solvent includes benzene, ethylbenzene, chlorobenzene, toluene, Xylene, etc. may be mentioned, but the present invention is not limited thereto.

Hereinafter, embodiments of the present invention will be described in detail.

Manufacturing Example 1-1

29.5 parts by weight of high-density polyethylene having a weight average molecular weight (M _w ) of 350,000, 0.5 parts by weight of trimethoxyvinylsilane-modified high-density polyethylene having a MFR of 0.8 g/10min and a density of 0.958 g/ml, and a paraffin having a kinematic viscosity of 70 cSt at 40°C 70 parts by weight of oil was mixed and put into a twin screw extruder (internal diameter 58mm, L/D=56, Twin screw extruder). A base sheet having a thickness of 800 μm was prepared by discharging from the twin-screw extruder to a T-die having a width of 300 mm under conditions of 200°C and a screw rotation speed of 40 rpm and passing through a casting roll having a temperature of 40°C. The base sheet was stretched 6 times in the longitudinal direction (MD) in a 110°C roll stretching machine and 7 times in the transverse direction (TD) in a 125°C tenter stretching machine to prepare a stretched film. The stretched film was impregnated in a dichloromethane leaching tank at 25° C. to extract and remove paraffin oil for 1 minute. The film from which the paraffin oil was removed was dried at 50° C. for 5 minutes. Then, after heating at 125°C in a tenter stretching machine, it was stretched by 1.45 times in the transverse direction (TD) and then relaxed by 1.25 times. The film was crosslinked for 72 hours in a constant temperature and humidity tank at 85° C. and 85% humidity to prepare a porous support.

Preparation Example 1-2

29.5 parts by weight of high-density polyethylene having a weight average molecular weight (M _w ) of 350,000, 0.5 parts by weight of trimethoxyvinylsilane-modified high-density polyethylene having a MFR of 0.8 g/10min and a density of 0.958 g/ml, and a paraffin having a kinematic viscosity of 70 cSt at 40°C 70 parts by weight of oil was mixed and put into a twin screw extruder (internal diameter 58mm, L/D=56, Twin screw extruder). Dibutyltindilaurate, which is a crosslinking catalyst, was pre-dispersed in some of the paraffin oil, and added through a side feeder of the twin screw extruder to be 0.01% by weight based on the total weight of the material passing through the twin screw extruder. A base sheet having a thickness of 800 μm was prepared by discharging from the twin-screw extruder to a T-die having a width of 300 mm under conditions of 200°C and a screw rotation speed of 40 rpm and passing through a casting roll having a temperature of 40°C. The base sheet was stretched 6 times in the longitudinal direction (MD) in a 110°C roll stretching machine and 7 times in the transverse direction (TD) in a 125°C tenter stretching machine to prepare a stretched film. The stretched film was impregnated in a dichloromethane leaching tank at 25° C. to extract and remove paraffin oil for 1 minute. The film from which the paraffin oil was removed was dried at 50° C. for 5 minutes. Then, after heating at 125°C in a tenter stretching machine, it was stretched by 1.45 times in the transverse direction (TD) and then relaxed by 1.25 times. The film was crosslinked for 72 hours in a constant temperature and humidity tank at 85° C. and 85% humidity to prepare a porous support.

Manufacturing Example 1-3

A porous support was manufactured in the same manner as in Preparation Example 1-1, except that high-density polyethylene having a weight average molecular weight (M _w ) of 350,000 was replaced with a high-density polyethylene having a weight average molecular weight (M _w ) of 250,000.

Manufacturing Example 1-4

A porous support was manufactured in the same manner as in Preparation Example 1-2, except that high-density polyethylene having a weight average molecular weight (M _w ) of 350,000 was replaced with a high-density polyethylene having a weight average molecular weight (M _w ) of 250,000.

Manufacturing Example 1-5

The porous support was prepared in the same manner as in Preparation Example 1-1, except that the stretched film was not crosslinked in a thermo-hygrostat, but propylene glycol was added to a crosslinking bath heated to 160°C and passed through for 30 minutes continuously. Was prepared.

Preparation Example 1-6

The stretched film is not crosslinked in a thermo-hygrostat, and a solution of propylene glycol and dibutyltindilaurate in a weight ratio of 95:5 is added to a crosslinking tank heated to 160℃ and passed through for 10 minutes in a continuous manner to crosslink. Except for that, a porous support was prepared in the same manner as in Preparation Example 1-1.

Manufacturing Example 1-7

The porous support was prepared in the same manner as in Preparation Example 1-1, except that the stretched film was not crosslinked in a constant temperature and humidity tank, and ethylene glycol was added to a crosslinking bath heated to 120°C and passed through for 60 minutes in a continuous manner. Was prepared.

Manufacturing Example 1-8

The stretched film is not crosslinked in a thermo-hygrostat, and a solution in which ethylene glycol and dibutyltindilaurate are mixed in a weight ratio of 90:10 is added to a crosslinking tank heated to 120℃, and is passed through continuously for 15 minutes to crosslink. Except for that, a porous support was prepared in the same manner as in Preparation Example 1-1.

Manufacturing Example 1-9

20 parts by weight of nanosilica particles having an average particle size of 600 nm coated with ethylene, 29.5 parts by weight of high-density polyethylene having a weight average molecular weight (M _w ) of 350,000, MFR 0.8 g/10min, trimethoxyvinylsilane having a density of 0.958 g/ml 0.5 parts by weight of modified high-density polyethylene, and 70 parts by weight of paraffin oil having a kinematic viscosity of 70 cSt at 40°C were mixed, and nanosilica particles were dispersed using a high-speed mixer.

Thereafter, after removing the fine bubbles generated in the mixing process through a vacuum defoaming process, it was put into a twin screw extruder (inner diameter 58mm, L/D=56). A base sheet having a thickness of 800 μm was prepared by discharging from the twin-screw extruder to a T-die having a width of 300 mm under conditions of 200°C and a screw rotation speed of 40 rpm and passing through a casting roll having a temperature of 40°C. At this time, the input content was controlled so that the content of nanosilica in the base sheet was 51.4% by weight. The base sheet was stretched 6 times in the longitudinal direction (MD) in a 110°C roll stretching machine and 7 times in the transverse direction (TD) in a 125°C tenter stretching machine to prepare a stretched film. The stretched film was impregnated in a dichloromethane leaching tank at 25° C. to extract and remove paraffin oil for 1 minute. The film from which the paraffin oil was removed was dried at 50° C. for 5 minutes. Then, after heating at 125°C in a tenter stretching machine, it was stretched by 1.45 times in the transverse direction (TD) and then relaxed by 1.25 times. The film was crosslinked for 72 hours in a constant temperature and humidity tank at 85° C. and 85% humidity to prepare a porous support.

Comparative Production Example 1

Mix 55 parts by weight of paraffin oil with a kinematic viscosity of 70 cSt at 40°C to 45 parts by weight of silane-modified polyethylene with MFR 0.8g/10min and density 0.958g/cm ³ and put into a twin screw extruder (internal diameter 58mm, L/D=56) I did. A base sheet having a thickness of 60 μm was prepared by discharging from the twin-screw extruder to a T-die having a width of 300 mm under conditions of 160°C and a screw rotation speed of 40 rpm and passing through a casting roll having a temperature of 40°C. After applying an aqueous dispersion of dibutyltindilaurate having a concentration of 30% by weight on both sides of the base sheet, a crosslinking reaction was carried out in hot water at 85°C for 1 hour to prepare a crosslinked film. The crosslinked film was impregnated in a dichloromethane leaching tank at 25°C to extract and remove paraffin oil for 30 minutes. The crosslinked film was dried in an oven at a temperature of 80° C. for 30 minutes to prepare a porous support.

Comparative Production Example 2

35 parts by weight of high-density polyethylene having a melting temperature of 135°C and a weight average molecular weight of 300,000, 65 parts by weight of paraffin oil having a kinematic viscosity of 40 cSt at 40°C, 2 parts by weight of trimethoxyvinylsilane, 2 parts by weight of dibutyltindilaurate And 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane (2,5-dimethyl-2,5-di (tert-butylperoxy) hexane) by mixing 2 parts by weight of a twin-screw extruder (internal diameter 58 mm) , L/D=56). A silane-modified polyolefin composition was prepared by reaction extrusion in the twin-screw extruder under conditions of 200°C and a screw rotation speed of 30 rpm, and discharged through a T-die having a width of 300 mm and passed through a casting roll having a temperature of 40°C to a thickness of 800 μm. An in base sheet was prepared. The base sheet was stretched 5.5 times in the longitudinal direction (MD) in a roll stretching machine at 108° C., and stretched 5.5 times in the transverse direction (TD) in a tenter stretching machine at 123° C. to prepare a stretched film. The stretched film was impregnated in a dichloromethane leaching tank at 25° C. to extract and remove paraffin oil for 10 minutes. The film from which the paraffin oil was removed was heat-set at 127°C to prepare a porous support. The porous support was crosslinked for 24 hours in a constant temperature and humidity tank at 80° C. and 90% humidity to prepare a porous support.

Comparative Production Example 3

5 parts by weight of high-density polyethylene having a weight average molecular weight of 500,000, 10 parts by weight of silane-modified polyethylene having a MFR of 0.5 g/10 min and a density of 0.942 g/ml, and 85 parts by weight of paraffin oil having a kinematic viscosity of 60 cSt at 40° C. It was put into an extruder (inner diameter 58mm, L/D=56). After discharging from the twin-screw extruder to a T-die having a width of 300 mm under conditions of 160°C and a screw rotation speed of 40 rpm, passing through a casting roll having a temperature of 40°C and rolling at 115°C to obtain a base sheet having a thickness of 500 μm . Was prepared. If some defects occurred in the manufacturing process of the base sheet, it was discarded, and a base sheet having a normal appearance was selected and used.

The base sheet was stretched 3.5 times in the longitudinal direction (MD) in a roll stretching machine at 115°C, and stretched 3.5 times in the transverse direction (TD) in a tenter stretching machine at 115°C to prepare a stretched film. The stretched film was impregnated in a dichloromethane leaching tank at 25° C. to extract and remove paraffin oil for 1 minute. The film from which the paraffin oil was removed was dried at 50° C. for 5 minutes, and the film was crosslinked for 24 hours in a constant temperature and humidity tank at 90° C. and 95% humidity. Thereafter, heat treatment was performed at 110° C. for 30 minutes to prepare a porous support.

Comparative Production Example 4

A porous support was prepared in the same manner as in Preparation Example 1-1, except that the stretched film was not crosslinked in a constant temperature and humidity tank, but was added to a crosslinking tank loaded with boiling water and passed through in a continuous manner.

Comparative Production Example 5

A porous support was prepared in the same manner as in Preparation Example 1-1, except that the stretched film was not crosslinked in a constant temperature and humidity tank, but was added to a crosslinking tank supported by hot water heated to 80°C and passed through in a continuous manner. .

Experimental Example 1

The test method for each of the physical properties measured in the present invention is as follows. If there is no separate mention of the temperature, it was measured at room temperature (25 ℃).

-Thickness ( μm ): The thickness of the support specimen was measured using a fine thickness meter.

-Porosity (%): According to ASTM F316-03, the porosity of a support specimen having a radius of 25 mm was measured using a Capillary Porometer of PMI.

-Permeability (Gurley, sec/100ml): Using the Asahi Seiko's Densometer EGO2-5 model, the time for 100ml of air to pass through a support specimen with a diameter of 29.8mm at a measurement pressure of 0.025MPa was measured.

-Crosslinking degree (gel fraction, %): 100mg (W ₀ ) of the support specimen was immersed in 1,2,4-trichlorobenzene and then heat-treated at 130°C for 2 hours. After separating the specimen and drying it at 50° C. for 24 hours, the weight (W) of the dried specimen was measured and the degree of crosslinking was calculated using the following calculation formula.

-Tensile strength (kgf/cm ² ): The applied stress was measured until fracture of the specimen occurred by applying stress to a support specimen having a size of 20 × 200 mm using a tensile strength meter.

-Tensile elongation (%): Using a tensile strength meter, a stress was applied to a support specimen having a size of 20 × 200 mm, and the maximum length extended until fracture of the specimen occurred was measured, and the tensile elongation was calculated using the following calculation formula.

(In the above calculation formula, l ₁ is the length in the horizontal or vertical direction of the specimen before stretching, and l ₂ is the length in the horizontal or vertical direction of the specimen just before fracture.)

-Punching strength (gf): Using a KES-G5 model of a punching strength measuring instrument from KATO TECH, a force is applied to a support specimen of 100 × 50 mm at a speed of 0.05 cm/sec with a stick having a diameter of 0.5 mm. The force applied at the time the specimen was pierced was measured.

-Meltdown temperature (°C): After applying a force of 0.01N to the support specimen using a thermomechanical analysis, the temperature was raised at a rate of 5°C/min to measure the degree of deformation of the specimen. The temperature at which the specimen breaks was taken as the meltdown temperature.

-Heat shrinkage rate (%): After placing a 200×200mm support specimen between A4 paper for 1 hour in an oven at 120°C, cooling it at room temperature, and measuring the contracted length of the specimen in the horizontal and vertical directions. Heat shrinkage was calculated using the formula.

(In the above calculation formula, l ₃ is the length in the horizontal or vertical direction of the specimen before shrinkage, and l ₄ is the length in the horizontal or vertical direction of the specimen after shrinking.)

The porous support prepared according to the above Preparation Example was photographed by SEM and shown in FIG. 1.

The physical properties of the support prepared according to Preparation Example and Comparative Preparation Example were measured, and the results are shown in Tables 1 and 2 below.

division Preparation Example 1-2 (before crosslinking) Preparation Example 1-2 (after crosslinking) Thickness( μm ) 9 9.6 Porosity (%) 50 52 Air permeability (sec/100ml) 124 129 MD tensile strength (kgf/cm ² ) 1,400 1,590 MD tensile elongation (%) 85 60 TD tensile strength (kgf/cm ² ) 955 1,090 TD tensile elongation (%) 60 55 MD heat contraction rate (%) 11 5 TD heat contraction rate (%) 17 10 Drilling strength (gf) 190 230 Meltdown temperature (℃) 150 210

division Manufacturing Example 1-1 Preparation Example 1-2 Comparative Production Example 1 Comparative Production Example 2 Comparative Production Example 3 Thickness( μm ) 9.4 9.6 25 14.3 26 Porosity (%) 50 52 43 33 42 MD tensile strength (kgf/cm ² ) 1,520 1,590 779 1,350 2,137 MD tensile elongation (%) 67 60 173 210 47 TD tensile strength (kgf/cm ² ) 1,020 1,090 543 1280 1,793 TD tensile elongation (%) 52 55 159 183 33 MD heat contraction rate (%) 7 5 12 11 17 TD heat contraction rate (%) 11 10 14 13 19 Drilling strength (gf) 210 230 150 480 350 Meltdown temperature (℃) 205 210 177 190 185

Experimental Example 2

The paraffin oil regenerated after extraction in the dichloromethane leaching tanks of Preparation Example 1-2 and Comparative Preparation Examples 1 and 2 was subjected to inductively coupled plasma atomic emission spectroscopy (ICP), and the results are shown in Table 3 below. Indicated.

division Si content (mg/kg) Sn content (mg/kg) Remark Preparation Example 1-2 5 3 Within measurement error Comparative Production Example 1 4~5 1~2 Within measurement error Comparative Production Example 2 220 7 -

Referring to Table 3, in Preparation Example and Comparative Preparation Example 1 using silane-modified polyolefin, the Si content per 1 kg of paraffin oil is 5 mg or less, which is within the measurement error, but Comparative Preparation Example 2 using trimethoxyvinylsilane is paraffin oil. 220 mg of Si was detected per 1 kg. In addition, as a result of additional analysis of the paraffin oil of Comparative Preparation Example 2, it was confirmed that a number of silanes were grafted to paraffin oil other than polyethylene during the grafting process of trimethoxyvinylsilane. The silane-modified paraffin oil was completely discarded because it was not regenerated.

Experimental Example 3

The porous support prepared according to Preparation Example and Comparative Preparation Example was divided into three portions in the transverse direction (TD), and the support specimen was extracted from each portion, and the degree of crosslinking, the puncture strength, and the meltdown temperature were measured, and are shown in Table 4 below. In Table 4 below, L denotes a value measured on a specimen of the support on one side, R on the other side, and M on the center side. The maximum difference is the greater of the difference between the M value and the L or R value.

division Preparation Example 1-2 Manufacturing Example 1-4 Comparative Production Example 2 Comparative Production Example 3 L punching strength (gf) 250 240 490 230 M Drilling strength (gf) 230 220 450 410 R punching strength (gf) 220 230 470 490 Maximum difference (gf) 30 20 40 260 L Melt down temperature (℃) 211 224 193 212 M meltdown temperature (℃) 208 215 179 157 R meltdown temperature (℃) 207 219 187 149 Maximum difference (℃) 4 9 14 63

Experimental Example 4

When crosslinking according to Preparation Examples and Comparative Preparation Examples, the gel fraction of the support according to the crosslinking time was measured to evaluate the reaction rate according to the crosslinking method and conditions, and the results are shown in Table 5 below.

Crosslinking time Manufacturing Example 1-5 Preparation Example 1-6 Comparative Production Example 4 Manufacturing Example 1-7 Manufacturing Example 1-8 Comparative Production Example 5 2 30 34 0 - - - 5 42 69 4 5 20 0 10 55 70 12 12 48 0 15 65 - 25 20 61 5 30 70 - 50 42 - 6 45 - - 70 - - - 60 - - - 60 - 11

Referring to Table 5, in the case of Preparation Examples 1-5 and 1-6, in which the crosslinking reaction was performed continuously in a crosslinking tank in which propylene glycol (boiling point: 188.2°C) was supported, about 70% of Comparative Preparation Example 4 Preparation Example 1 in which the time required to achieve the degree of crosslinking was reduced to a maximum of 1/3 or less, and a crosslinking reaction was carried out in a continuous manner in a crosslinking tank carrying ethylene glycol (boiling point: 197.3°C) having a higher boiling point than propylene glycol. In the cases 7, 1-8, the time required to achieve a degree of crosslinking of about 60% was reduced to a maximum of 1/10 or less compared to Comparative Preparation Example 5.

Manufacturing Example 2

In order to modify the surface of the porous support of Preparation Examples 1-1 to 1-8, it was treated with vacuum plasma. Before plasma treatment, the porous support was inserted into a frame capable of maintaining a flat state and purged with nitrogen to remove impurities on the support.

The chamber size of the apparatus for vacuum plasma treatment is 150mm in width, 200mm in depth, and 120mm in height, and a planar electrode for generating plasma is installed in parallel with the upper surface of the chamber at a location 25mm away from the upper surface. The porous support was placed in parallel with the planar electrode at a position 20 mm away from the planar electrode, and a vacuum condition was created until the pressure inside the chamber became 0.1 torr.

The gas having the composition according to Table 6 was introduced into the chamber at a flow rate of 100 sccm, and the pressure inside the chamber was maintained at 0.5 torr for 2 minutes to purify. In addition, by applying a high-frequency power having a frequency of 50KHz at an output of 100W, the porous support was treated for the time according to Table 6 below. After the treatment, gas inflow into the chamber was blocked and the pressure was maintained at 0.5 torr, purged with air for 2 minutes, and the vacuum condition was released to open the chamber.

The upper and lower surfaces of the porous support were turned over and placed in the chamber in the same manner as described above, and the same process was repeated to ensure that both surfaces of the porous support, that is, the upper and lower surfaces, were evenly treated.

By measuring the contact angle of the second distilled water droplet on the surface of the surface-treated porous support, the change in the hydrophilic properties of the porous support was evaluated, and the zeta potential of the surface of the porous support was measured using a flow potential method. The charging properties of the porous support were evaluated. The measurement and evaluation results after the hydrophilic modification of the support prepared in Preparation Example 1-1 are typically shown in Table 6 below.

division A B C D E F G Gas composition
(O ₂ : SO ₂ , vol%) 50: 50 20: 80 20: 80 20: 80 20: 80 - air Plasma treatment time (min) 120 120 90 60 30 - 120 Contact angle (degree, ˚) 3 0 0 4 13 110 99 Zeta potential (mV) -9 -25 -22 -17 -10 -2 -3

Referring to Table 6, the porous support that has not undergone plasma surface treatment (F) has very strong hydrophobicity and the surface is weakly charged by silane, while plasma is formed using a gas in which oxygen and sulfur dioxide are mixed in a certain ratio as a process gas. The surface-treated porous scaffolds (A to E) had a negative charge and remarkably enhanced hydrophilicity.

In addition, when the non-plasma surface-treated support of F and the plasma surface-treated support of A are immersed in distilled water, the support of F floats in water due to the property that water does not penetrate into the pores and the surface is in contact with air. While it is opaque by light scattering due to the difference in refractive index between the polyethylene materials, the support of A can be well immersed in the water by infiltrating water into the pores, and due to the moderate difference in refractive index between the water filling the pores and the polyethylene material. This makes it appear transparent.

In addition, from A and B, it can be seen that when the ratio of sulfur dioxide in the process gas is larger than that of oxygen, the surface of the porous support is more effectively hydrophilically modified.

Manufacturing Example 3-1

Polysulfone 354.4 g (0.8 mol) and dichloroethane 3,900 ml were added to a 5-neck 5 L reactor equipped with a mechanical stirrer, a gas inlet, and a cooler, and stirred at room temperature for 12 hours or more under a nitrogen atmosphere.

When the dissolution was complete, 259.3 ml (2 mol) of chlorotrimethylsilane was added using a dropping funnel, and 134.4 ml (2 mol) of chlorosulfonic acid and 100 ml of dichloroethane were mixed and slowly added. After the addition was completed, it was reacted for 6 hours.

After the reaction was completed, the product was slowly added to methanol to precipitate, washed 2 to 3 times to remove residual dichloroethane, and then added to an aqueous NaCl solution to convert Na ⁺ ions in the form of a salt, followed by pulverization and washing.

The product was neutralized using a 10N NaOH aqueous solution using a mechanical stirrer, washed with water, filtered, and dried under reduced pressure in a vacuum oven at 80° C. for 24 hours to obtain a sulfonated polysulfone having a degree of sulfonation of 80%. The sulfonated polysulfone was dissolved in NMP at a concentration of 30 to 60% by weight at 60° C. for 2 hours to prepare an electrolyte.

Manufacturing Example 3-2

To a 5-neck 150 ml reactor equipped with a mechanical stirrer, a gas inlet, and a cooler, 20 g of perfluorosulfonic acid, 30 ml of water, and 70 ml of alcohol were added to the reactor, followed by stirring at room temperature for at least 2 hours under a nitrogen atmosphere. After stirring, 10 ml of NMP was additionally added and stirred for at least 30 minutes to prepare an electrolyte.

Example 1

The porous support that went through the process of Preparation Example 2 was impregnated with the electrolyte solution of Preparation Example 3-1 to prepare an ion exchange membrane.

The ion exchange membrane prepared according to the above example was photographed by SEM and shown in FIG. 2.

In order to quantify the performance and durability of the prepared membrane, the cation transfer water was measured in 0.5N sodium chloride aqueous solution, respectively, immediately after the ion exchange membrane was prepared by impregnation and after 2 days of storage in distilled water, and representatively, Preparation Example 1- The physical properties of the ion exchange membrane prepared based on the support of 1 are shown in Table 7 below.

division A B F G Exfoliation after 2 days of storage in distilled water Not occurring Not occurring Occur Occur Cation transfer water immediately after preparation 0.95 0.94 0.95 0.95 Cation transfer water after 2 days of storage of distilled water 0.94 0.94 0.62 0.59

Referring to Table 7 above, when an ion exchange membrane is prepared by impregnating a polymer electrolyte into a porous membrane of a substrate that has not undergone plasma surface treatment or is treated with air using air as a process gas (F, G), distilled water is stored for 2 days. After lapse, a peeling phenomenon between the polymer electrolyte and the porous substrate film was observed. In addition, in the case of F and G, the number of cation transfers measured immediately after the ion exchange membrane was prepared reached 0.95, but after 2 days of storage in distilled water, it decreased significantly to less than 0.62, indicating that the durability as an ion exchange membrane was low. On the other hand, oxygen and sulfur dioxide were found to have low durability. In the case of the ion exchange membrane manufactured by impregnating the porous membrane (A, B) of the substrate with plasma surface treatment with the gas mixed in a certain ratio as the process gas, no peeling phenomenon was observed even when stored in distilled water for 2 days or longer. It was maintained above 0.94 with little change in the number of cation transfers.

Example 2

The porous support that went through the process of Preparation Example 2 was impregnated with the electrolyte solution of Preparation Example 3-2 to prepare an ion exchange membrane.

The performance and durability of the prepared membrane were evaluated by the following method, and the results are shown in Table 8 below.

-Ion conversion rate (IEC, meq/g): The degree of inclusion of ion exchange groups in the ion exchange membrane can be known through the ion conversion rate, and was measured using an acid-base titration method. The ion exchange membrane was immersed in a 0.01N sodium chloride aqueous solution for 24 hours, followed by titration using a 0.01N sodium hydroxide solution, and the ion conversion rate was calculated using the following equation.

In the above formula, V _NaOH is the volume of the aqueous sodium hydroxide solution used in the titration, N _NaOH is the normal concentration of the sodium hydroxide aqueous solution, and W _dry is the weight of the dried ion exchange membrane.

-Water absorption rate (water uptake, %): To measure the water absorption rate of the ion exchange membrane, the ion exchange membrane was washed several times with deionized water, and the washed ion exchange membrane was immersed in deionized water for 24 hours. After removing the water present, the weight (W _wet ) was measured. Subsequently, the same ion exchange membrane was dried again in a vacuum dryer at 120° C. for 24 hours, and then the weight (W _dry ) was measured again, and the water absorption rate was calculated using the following equation.

-Dimensional stability (Δl, Δt, ΔV, %): Dimensional stability is the same as the water absorption rate, but instead of weight, the length, thickness, and volume change of the ion exchange membrane were measured, and the dimensional change rate was calculated using the following equation. I did.

division IEC Δl Δt ΔV Water absorption rate A 1.37 2.2 2.71 7.81 9.80 B 1.32 2.0 2.11 5.22 7.51 F 1.10 5.11 6.35 17.93 11.93

Referring to Table 8, the ion exchange membranes (A, B) prepared by impregnating the electrolyte into the plasma surface-treated substrate porous membrane in the presence of a mixed gas containing sulfur dioxide (SO ₂ ) and oxygen (O ₂ ), the ion conversion rate This is higher than the ion exchange membrane (F) manufactured by impregnating the porous membrane with an electrolyte in the substrate porous membrane that has not undergone plasma surface treatment at a rate of about 1.1 meq/g or more, and has excellent ion conductivity and reduced the length change rate by about 60-70%. The dimensional stability was improved, and the water absorption rate was also lowered to 10% or less, indicating excellent durability as an ion exchange membrane. The foregoing description of the present invention is for illustration purposes only, and those of ordinary skill in the art to which the present invention pertains the present invention. It will be understood that it can be easily transformed into other concrete forms without changing the technical idea or essential features of Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims to be described later, and all changes or modified forms derived from the meaning and scope of the claims and the concept of equivalents thereof should be construed as being included in the scope of the present invention.

Claims (24)

A porous support comprising a continuous phase matrix comprising a polyolefin having a weight average molecular weight (M _w ) of 250,000 to 450,000, and a discontinuous silane-modified polyolefin crosslinked in the matrix; And
Including; an electrolyte impregnated in the pores of the porous support or applied to the surface,
The content of the silane-modified polyolefin in the porous support is 0.1 to 5% by weight, ion exchange membrane. The method of claim 1,
The porous support further comprises an inorganic filler, ion exchange membrane. The method of claim 2,
The content of the inorganic filler in the porous support is 10 to 70% by weight, ion exchange membrane. delete The method of claim 1,
The silane is a vinyl silane containing an alkoxy group, ion exchange membrane. The method of claim 1,
The porous support satisfies one or more of the following conditions (i) to (ix), ion exchange membrane:
(i) air permeability 125~300sec/100ml;
(ii) punching strength 200~400gf;
(iii) Tensile strength in the longitudinal direction (MD) 1,500~3,000kgf/cm ² ;
(iv) Transverse direction (TD) tensile strength 1,000~2,500kgf/cm ² ;
(v) 80% or less of tensile elongation in the longitudinal direction (MD);
(vi) 55% or less of tensile elongation in the transverse direction (TD);
(vii) 10% or less of longitudinal heat shrinkage at 120°C;
(viii) 15% or less in transverse direction heat shrinkage at 120°C;
(ix) Meltdown temperature 200~250℃. The method of claim 1,
The average pore size of the porous support is 20 ~ 2,000nm, ion exchange membrane. The method of claim 1,
The porous support has a contact angle of 15˚ or less, an ion exchange membrane. The method of claim 1,
The porosity of the porous support is 30 to 90%, the ion exchange membrane. The method of claim 1,
The electrolyte is an ion exchange membrane containing a sulfonated polymer, a fluorine-based compound, or a combination thereof. The method of claim 10,
The sulfonation degree of the sulfonated polymer is 60 to 90%, the ion exchange membrane. The method of claim 10,
The sulfonated polymer is a polysulfone series, a poly(ethersulfone) series, a poly(thiosulfone) series, a poly(etheretherketone) series, a polyimide series, a polystyrene series, a polyphosphazene series, and a mixture of two or more of them. One sulfonated hydrocarbon-based polymer selected from the group consisting of, the ion exchange membrane. The method of claim 10,
The fluorine-based compound is perfluorosulfonic acid, poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), a copolymer of tetrafluoroethylene and fluorovinyl ether containing a sulfonic acid group, polytetrafluoroethylene, Polyvinyl fluoride, polyvinylidene fluoride, polyhexafluoropropylene, and one selected from the group consisting of two or more copolymers or combinations thereof, the ion exchange membrane. (a) manufacturing a porous support by processing a composition comprising 20 to 40 parts by weight of a polyolefin having a weight average molecular weight (M _w ) of 250,000 to 450,000 and 0.1 to 10 parts by weight of a silane-modified polyolefin;
(b) crosslinking the silane-modified polyolefin contained in the porous support; And
(c) impregnating the porous support into an electrolyte solution containing an electrolyte and a solvent; and,
In the product of the step (b), the polyolefin and the crosslinked silane-modified polyolefin constitute a continuous phase and a discontinuous phase, respectively. The method of claim 14,
The composition further comprises a crosslinking catalyst, a method for producing an ion exchange membrane. The method of claim 15,
The content of the crosslinking catalyst in the composition is 0.01 to 5% by weight, the method for producing an ion exchange membrane. The method of claim 14,
In the step (b), the support is introduced into a crosslinking tank in which a solution having a boiling point exceeding 100°C is supported and continuously passed through the method for producing an ion exchange membrane. The method of claim 17,
The (b) step is made at a temperature of 120 ℃ or higher, the method of manufacturing an ion exchange membrane. The method of claim 17,
The solution further comprises a crosslinking catalyst, the method of manufacturing an ion exchange membrane. The method of claim 17,
The content of the crosslinking catalyst in the solution is 0.5 to 15% by weight, the method for producing an ion exchange membrane. The method of claim 14,
Before step (c),
Plasma treatment of the support in the presence of a mixed gas containing sulfur dioxide (SO ₂ ) and oxygen (O ₂ ); further comprising, a method of manufacturing an ion exchange membrane. The method of claim 21,
The method for producing an ion exchange membrane, wherein the mixed gas contains 50 to 90% by volume of sulfur dioxide and 10 to 50% by volume of oxygen. The method of claim 21,
The plasma treatment is performed for 0.5 to 90 minutes, the method of manufacturing an ion exchange membrane. The method of claim 14,
A method of manufacturing an ion exchange membrane, wherein the content of the electrolyte in the electrolyte is 10 to 60% by weight.

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