KR101451567B1 - Porous support, method for manufacturing the same, and reinforced membrane comprising the same - Google Patents

Abstract

The present invention relates to a porous support, a method for manufacturing the same, and a reinforced membrane including the same. The porous support includes a nanoweb in which polyimide nanofibers are integrated in a form of nonwoven cloth including a plurality of pores. A main chain of the polyimide includes hydrophilic substituents. The porous support has excellent air permeability, water permeability, heat resistance, chemical resistance, and hydrophile.

Description

TECHNICAL FIELD [0001] The present invention relates to a porous support, a method for producing the porous support, and a reinforced membrane comprising the porous support,

The present invention relates to a porous support, a method for producing the same, and a reinforcing membrane comprising the porous support. More particularly, the present invention relates to a porous support excellent in durability, heat resistance and chemical resistance as well as excellent in hydrophilicity, And a reinforcing film comprising the same.

Since nanofibers have a wide surface area and excellent porosity, they are used in various applications such as water purification filters, air purification filters, composite materials, and separators for batteries. Especially, they can be effectively applied to reinforced composite membranes used in fuel cells for automobiles.

Fuel cells are an electrochemical device that is powered by hydrogen and oxygen, and they are now becoming environmentally friendly because their products are pure water and reusable heat. In addition, it is widely used as a power source for household, automobile, and power generation due to simple operation, high output density and quietness.

Fuel cells can be divided into alkali electrolyte fuel cells, direct oxidation fuel cells, polymer electrolyte membrane fuel cells (PEMFC) and the like depending on the type of electrolyte membrane. Among them, polymer electrolyte membrane fuel cells are classified into hydrogen ion H ⁺ ) is generated from the anode to the cathode and generates electricity. The fuel cell can operate at room temperature and has a shorter activation time than other fuel cells.

A polymer electrolyte membrane fuel cell includes an electricity generating unit including a membrane electrode assembly (MEA) and a separator (also referred to as a bipolar plate) in which an oxide electrode and a reducing electrode are formed with a polymer electrolyte membrane interposed therebetween, A fuel supply unit for supplying fuel to the electricity generation unit, and an oxidant supply unit for supplying an oxidant such as oxygen or air to the electricity generation unit.

The polymer electrolyte membrane can be divided into a single membrane composed of a polymer such as a fluorine-based or hydrocarbon-based polymer as a conductor of a hydrogen ion and a composite membrane formed by combining an organic or inorganic material or a porous support together with the polymer. In the case of a single membrane, Nafion (TM) of DuPont, which is a perfluorinated polymer, is most widely used, but it is expensive, has low mechanical stability, and has a thick membrane resistance.

In order to overcome these disadvantages, research has been actively conducted on composite membranes having enhanced mechanical and morphological stability. Among them, porous membrane having a concept of impregnating an ion conductor on a porous support is not only inexpensive, but also has performance mechanical and shape stability Many studies have been made.

Polytetrafluoroethylene (PTFE) is used as a general support for pore filling membranes. However, the PTFE support has a problem that the chemical resistance is excellent but the porosity is as low as 40 to 60%.

Korean Patent Laid-Open No. 2011-0120185 (published on November 3, 2011)

An object of the present invention is to provide a porous support excellent in durability, heat resistance and chemical resistance as well as excellent in hydrophilicity while having excellent air permeability and passage capacity.

Another object of the present invention is to provide a method for producing the porous support.

It is another object of the present invention to provide a reinforcing membrane comprising the porous support.

According to one embodiment of the present invention, the polyimide nanofibers include a nanoweb integrated into a nonwoven fabric including a plurality of pores, wherein the main chain of the polyimide provides a porous support comprising a hydrophilic substituent.

The hydrophilic substituent may include any one substituent selected from the group consisting of an amine group, a carboxyl group, a hydroxyl group, and combinations thereof.

The polyimide may be prepared by imidizing a polyamic acid prepared by polymerizing a comonomer including a diamine, a dianhydride, and a hydroxy group.

The comonomer containing a hydroxy group may be any one selected from the group consisting of dianiline including a hydroxy group, diphenylurea including a hydroxy group, diamine including a hydroxy group, and combinations thereof.

The saturation hindrance time of the nano web may be 1 second to 5 minutes.

The moisture content of the nano-web may be 3.0% or more.

The nano-web may have a wettability of 2 to 15 cm by a wicking test.

The nano-web may have a contact angle of 90 ° or less.

The nanofiber may include 0.1 to 20 parts by weight of a hydrophilic additive to 100 parts by weight of the nanofiber polymer.

The hydrophilic additive may be impregnated into the pores of the nanoweb.

The hydrophilic additive may be coated on one surface or both surfaces of the nano web.

The hydrophilic additive may be selected from the group consisting of anatase type titanium dioxide (TiO ₂ anatase), rutile type titanium dioxide (TiO ₂ rutile), brookite type titanium dioxide (TiO ₂ brookite), tin dioxide (SnO ₂ ), zirconium dioxide Aluminum (Al ₂ O ₃ ), oxidized single wall carbon nanotube, oxidized multiwall carbon nanotube, oxidized graphite oxide, oxidized graphene, and combinations thereof.

Wherein the hydrophilic additive is selected from the group consisting of polyhydroxyethyl methacrylate polyvinyl acetate, polyurethane, polydimethylsiloxane, polyimide, polyamide, polyethylene terephthalate, polymethyl methacrylate, epoxy, It can be one.

The hydrophilic additive may be an nano-hydrophilic additive having an average particle diameter of 0.005 to 1 mu m.

The nanoweb may be plasma treated on one or both surfaces.

An inorganic material may be deposited on one or both surfaces of the nano web.

The inorganic material may be selected from the group consisting of anatase type titanium dioxide (TiO ₂ anatase), rutile type titanium dioxide (TiO ₂ rutile), brookite type titanium dioxide (TiO ₂ brookite), tin dioxide (SnO), zirconium dioxide (ZrO ₂ ) Al ₂ O ₃ , oxidized single wall carbon nanotubes, oxidized multiwall carbon nanotubes, oxidized graphite oxide, oxidized graphene, and combinations thereof.

According to another embodiment of the present invention, there is provided a method for producing an electrospinning solution, comprising the steps of: preparing an electrospinning solution by adding a diamine and a dianhydride to a solvent; electrospinning the electrospinning solution to prepare a nanofibers in the form of a nonwoven fabric Preparing an integrated polyamic acid nano-web, and imidizing the polyamic acid nano-web to produce a polyimide nano-web, wherein the main chain of the nano- A carboxyl group, a hydroxyl group, and a combination thereof. The present invention also provides a method for producing a porous support.

The diamine or the dianhydride may be substituted with any one substituent selected from the group consisting of an amine group, a carboxyl group, a hydroxyl group, and combinations thereof.

The method may further include the step of preparing the polyimide nanoweb or the polyamic acid nanoweb and then replacing the hydrophilic substituent with the main chain of the polyimide or the polyamic acid.

A comonomer containing a hydroxy group may be further added to the electrospinning solution.

A hydrophilic additive may be further added to the electrospinning solution.

And further impregnating the inside of the pores of the nano web with a hydrophilic additive.

The method may further include coating a hydrophilic additive on one surface or both surfaces of the nano web.

The method may further include plasma-treating one or both surfaces of the nano-web.

The plasma treatment may be performed using a gas capable of imparting a hydrophilic group to one or both surfaces of the nanoweb by using a low-temperature plasma or a radio frequency (RF) plasma.

The method may further include depositing an inorganic material on one or both surfaces of the nano web.

The method of depositing the inorganic material may be sputtering.

According to another embodiment of the present invention, there is provided a reinforced membrane comprising the porous support and an ion exchange polymer filling the pores of the porous support.

Other details of the embodiments of the present invention are included in the following detailed description.

The porous support according to the present invention is excellent in durability, heat resistance and chemical resistance as well as excellent in hydrophilicity because it has excellent air permeability and water permeability.

1 is a schematic view of a nozzle-type electrospinning device.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "comprises" or "having" are used to designate the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

The term "nano," as used herein, refers to nanoscale and includes a size of 1 μm or less.

The term "diameter " as used herein means the length of the minor axis passing through the center of the fiber, and" length "means the length of the major axis passing through the center of the fiber.

A porous support according to an embodiment of the present invention includes a nanofiber in which nanofibers are integrated into a nonwoven fabric including a plurality of pores.

The nanofiber exhibits excellent chemical resistance and can be preferably used because it has hydrophobicity and has no fear of morphological change due to moisture in a high humidity environment. Examples of the hydrocarbon-based polymer include nylon, polyimide, polyaramid, polyetherimide, polyacrylonitrile, polyaniline, polyethylene oxide, polyethylene naphthalate, polybutylene terephthalate, styrene butadiene rubber, polystyrene, polyvinyl chloride, Polyolefins such as polyvinyl alcohol, polyvinylidene fluoride, polyvinyl butylene, polyurethane, polybenzoxazole, polybenzimidazole, polyamideimide, polyethylene terephthalate, polyethylene, polypropylene, copolymers thereof and mixtures thereof . Among them, polyimide having better heat resistance, chemical resistance, and shape stability can be preferably used.

The porous support includes a collection of nanofibers in which nanofibers produced by electrospinning are randomly arranged, that is, nanobubbles. In consideration of the porosity and thickness of the nanofibers, the nanofibers were measured for 50 fiber diameters using a scanning electron microscope (JSM6700F, JEOL) and the average of 40 to 5000 nm Diameter. If the average diameter of the nanofibers is less than 40 nm, the mechanical strength of the porous support may be lowered. If the average diameter of the nanofibers exceeds 5,000 nm, the porosity may be significantly decreased and the thickness may be increased.

The nano-web is made of the nanofiber as described above, and thus can have a porosity of 50% or more. Since the porous support has a specific surface area of 50% or more as described above, it is easy to impregnate the electrolyte when applied as a separation membrane, and as a result, the efficiency of the battery can be improved. On the other hand, the nano-web preferably has a porosity of 90% or less. If the porosity of the nano-web exceeds 90%, the morphology of the nano-web may be deteriorated and the post-process may not proceed smoothly. The porosity can be calculated according to the ratio of the volume of air to the total volume of the porous support according to Equation (1). In this case, a rectangular volume sample is prepared and measured by measuring the width, length, and thickness, and the air volume can be obtained by subtracting the volume of the polymer inversely calculated from the density after measuring the mass of the sample from the total volume.

[Equation 1]

Porosity (%) = (air volume in nano web / total volume of porous support) x 100

In addition, the nanoweb may have an average thickness of 5 to 50 탆. If the thickness of the nano-web is less than 5 탆, the mechanical strength and dimensional stability of the separator may be significantly deteriorated. On the other hand, when the thickness of the nano-web exceeds 50 탆, resistance loss increases, have. More preferably, the thickness of the nano-web is in the range of 10 to 30 占 퐉.

In order for the nano-web to have a thickness of nanofibers having excellent porosity and optimized diameter and being easy to manufacture and to exhibit excellent tensile strength after electrolyte impregnation, the polymer constituting the nano-web has a weight of 30,000 to 500,000 g / mol It is preferable to have an average molecular weight. If the weight average molecular weight of the polymer constituting the nano-web is less than 30,000 g / mol, porosity and thickness of the nano-web can be easily controlled, but tensile strength after porosity and wet treatment may be lowered. On the other hand, if the weight average molecular weight of the polymer constituting the nano-web exceeds 500,000 g / mol, the heat resistance may be somewhat improved, but the manufacturing process may not proceed smoothly and the porosity may be lowered.

The nano-web may have a weight average molecular weight in the range described above, and may have a heat resistance of 180 ° C or higher, preferably 300 ° C or higher, as the polymer precursor is converted into a polymer under optimal curing conditions. If the heat resistance of the nano-web is less than 180 ° C, the nano-web may be easily deformed at a high temperature as heat resistance deteriorates, and thus the performance of the electrochemical device manufactured using the nano-web may deteriorate. Also, when the heat resistance of the nano web is deteriorated, the shape of the nano web may be deformed due to abnormal heat generation, and the performance may be deteriorated.

The nano-web is insoluble in an organic solvent at room temperature to 100 < 0 > C and can be chemically stable. The organic solvent may be an organic solvent such as NMP, DMF, DMAc, DMSO, THF or the like.

The nano-web may have a strain of 10% or less and preferably 5% or less. The strain rate can be measured as an average of the transverse and longitudinal strains before and after leaving the nano-web at 100 ° C for 100 mm and 200 ° C for 24 hours. If the strain exceeds 10% by length, the dimensional stability of the support and morphological deformation can be achieved under high temperature environment.

When the nano-web is made of polyimide, the imide conversion may be 90% or more, preferably 99% or more. The imide conversion rate was measured by the infrared spectrum with respect to the nano web, it can be determined by calculating the ratio of the p- substituted CH absorbance already de CN absorbance versus 1500㎝ ^-1 in 1375㎝ ^-1. If the imide conversion is less than 90%, the physical properties and shape stability can not be secured due to unreacted materials.

The nano-web may have an air permeability of 50 to 250 lpm, and preferably 100 to 150 lpm. The air permeability can be measured by the ISO 9237 method. When the air permeability is less than 50 lpm, absorption of the electrolyte may become difficult, and when the air permeability exceeds 250 lpm, the electrolyte may not be sufficiently contained.

The nanoweb may have a saturated hydrophilic time of from 1 second to 5 minutes, preferably from 1 second to 3 minutes, and more preferably from 1 second to 60 seconds. The saturation humidification arrival time is determined by KS K ISO 9073-6, Textile - Nonwoven Fabric Test Methods - Part 6: Water Absorption Time in Absorption Measurement Standard, .

When the saturation humidification time is within the above range, the ion-exchange polymer may be impregnated into the nano-web to uniformly impregnate the ion-exchange polymer uniformly throughout the pores of the nano-web. Also, when the hydrophilic property of the nano-web is increased, a hydrophilic channel is further formed when the reinforced membrane is used as a membrane for a fuel cell, so that ion conductivity can be improved.

The nano-web may have an electrolyte absorption rate of 10 to 60% by weight, and preferably 30 to 40% by weight. The electrolyte absorptivity was measured according to KS K ISO 9073-6, Textile-Nonwoven Fabric Test Method, Part 6: Absorption Measurement Standard, liquid humidification time method, 70/30 (v / v) ratio of ethyl methyl carbonate and ethylene carbonate, v) The mixture can be dropped at a height of 25 mm to measure the time the specimen is completely wet. If the electrolyte absorptivity is less than 10 wt%, the electrolyte absorption may decrease and the battery performance may not be sufficiently exhibited. If the electrolyte absorptivity is more than 60 wt%, the physical properties of the support may deteriorate.

The nano-web may have a moisture regain of 3.0% or more, preferably 3.0 to 5.0%, and more preferably 3.1 to 5.0%. The moisture content was determined by measuring the weight (O: sample weight) after reaching moisture equilibrium in a fiber laboratory standard state (KS K 0901) for 24 hours in accordance with the method of moisture measurement of KS K 0221 textile: oven balance method , And dried at 105 to 110 ° C for 1 hour and 30 minutes, and then the weight (D: weight of the dried sample) is measured.

&Quot; (2) "

Moisture content (%) = (O-D) / D x 100

(O: weight of specimen, D: weight of dried specimen)

The nano-web may have a wettability by wicking test of 2 to 15 cm, preferably 2.1 to 15 cm, and more preferably 3 to 15 cm. The wicking test was conducted according to the AATCC Test Method 197-2011, Vertical Wicking of Textiles (Option B, Measure distance at a given time), 30 minutes after immersing the specimen Can be measured by a method of measuring the maximum wicking distance. If the wettability by the wicking test is less than 2 cm, the ion conductor and the support may be separated from each other in the operating environment of the fuel cell, the operation time may be delayed or the physical form stability may be deteriorated under the low humidity condition, Acceleration of the swelling of the ion conductor in a fuel cell operating environment may result in reduced durability, or the ion conductor and support may desorb.

The nano-web may have a contact angle of 90 ° or less, preferably 1 to 50 °, and more preferably 5 to 35 °. The contact angle was maintained at 30 DEG C and RH of 40%. Distilled water was charged into a syringe, water droplets having a diameter of 3 mm were dropped on the nanoweb, and water droplets were spread for 5 minutes. After 5 minutes, The contact angle can be measured. When the contact angle is less than 1 °, the wettability of the nano web is excellent. However, it may be difficult to manufacture the nano-web having an excessively high quality of the additive in the spinning process. It may be difficult to exhibit sufficient performance when used.

When the nanofiber is made of a hydrophobic polymer such as polyimide, it has an advantage of excellent heat resistance, chemical resistance, and shape stability. However, since the hydrophilic property is insufficient, the ion conductive polymer is uniformly dispersed And the ion conductivity may be lowered due to the lack of formation of the hydrophilic channel. Therefore, in order to satisfy the saturated wetting time, water content, wettability or contact angle by the wicking test, the hydrophobic polymer nanofibers need to be hydrophilized. The hydrophilization treatment can be applied to any conventional method for improving the hydrophilicity of the nano-web, and is not particularly limited in the present invention.

As an example of the hydrophilic treatment method of the nano-web, the nano-web may include a hydrophilic additive. That is, the nanofiber itself may include the hydrophilic additive, the hydrophilic additive may be impregnated into the pores of the nanoweb, and the hydrophilic additive may be coated on one or both surfaces of the nanoweb Lt; / RTI >

Specifically, when the nanofiber includes the hydrophilic additive, the nanofiber may include 0.1 to 20 parts by weight, preferably 0.5 to 20 parts by weight, more preferably 1 to 20 parts by weight of a hydrophilizing additive per 100 parts by weight of the nanofiber polymer, 2 parts by weight.

If the content of the hydrophilic additive is less than 0.1 parts by weight based on 100 parts by weight of the nanofiber polymer, the hydrophilic property may be insufficient and the wettability may be deteriorated to deteriorate the performance of the electrochemical device. If the amount exceeds 20 parts by weight, It is possible to increase the instability of nanofiber jets and cause uneven fiber concentration, which may cause problems when applied to a separator of an electrochemical device.

When the hydrophilic additive is impregnated into the pores of the nano-web or the hydrophilic additive is coated on one surface or both surfaces of the nano-web, the nano-web may have a hydrophilic additive of 0.1 To 20 parts by weight, preferably 3 to 20 parts by weight, more preferably 5 to 20 parts by weight.

If the content of the hydrophilic additive is less than 0.1 parts by weight based on 100 parts by weight of the nanoweb, the hydrophilic property may be insufficient and the wettability may be deteriorated to deteriorate the performance of the electrochemical device. If the amount exceeds 20 parts by weight, It is possible to increase the instability of the fiber jet and cause uneven fiber concentration, which may cause problems in application to the separator of the electrochemical device.

The nano-web is excellent in wettability by including the hydrophilic additive, and when used as a separator for an electrochemical device, the nano-web is excellent in wettability with respect to an electrolyte, thereby improving the efficiency of the battery. In addition, the porous support has excellent durability, heat resistance, and chemical resistance, so that the performance of the electrochemical device can be maintained even under harsh operating conditions.

The hydrophilic additive may be an inorganic or organic hydrophilic additive. The inorganic hydrophilic additive may be subjected to an oxidation and / or reduction reaction, that is, an electrochemical reaction, with an anode or an anode current collector in an operating voltage range of the electrochemical device (for example, 0 to 5 V based on Li / Li ⁺ And is not particularly limited as long as it can withstand the manufacturing process when manufacturing the nanofibers including the nanofibers.

For example, the inorganic hydrophilic additive may be selected from the group consisting of anatase type TiO ₂ anatase, rutile type TiO ₂ rutile, brookite type TiO ₂ brookite, tin dioxide (SnO 2), zirconium dioxide ZrO ₂ ), aluminum oxide (Al ₂ O ₃ ), oxidized single wall carbon nanotube, oxidized multiwall carbon nanotube, oxidized graphite oxide, oxidized graphene, and combinations thereof. preferably TiO may be _two days.

Further, the organic hydrophilic additive may also be oxidized and / or reduced with an anode or an anode current collector in an operating voltage range of the electrochemical device (for example, 0 to 5 V based on Li / Li ^{+ in} the case of a lithium secondary battery) There is no particular limitation so long as it does not cause a reaction, does not impair the conductivity, and can withstand the manufacturing process when manufacturing nanofibers containing the same.

For example, the organic hydrophilic additive may be selected from the group consisting of polyhydroxyethyl methacrylate polyvinyl acetate, polyurethane, polydimethylsiloxane, polyimide, polyamide, polyethylene terephthalate, polymethyl methacrylate, epoxy and combinations thereof Lt; / RTI > group.

The hydrophilic additive may be a nano-hydrophilic additive, and accordingly, the average particle diameter of the hydrophilic additive may be 0.005 to 1 탆, preferably 0.005 to 0.8 탆, more preferably 0.005 to 0.5 탆. If the average particle diameter of the nano-hydrophilic additive is less than 0.005 탆, the hydrophilization effect of the nano-hydrophilic particles may be impaired or the handling may be difficult. If the average particle diameter exceeds 1 탆, the physical tensile strength of the support may be lowered, Can be reduced.

As described above, when the nanofiber is made of polyimide, which is a hydrophobic polymer, the main chain of the polyimide has an amine group, a carboxyl group, a hydroxyl group, a hydroxyl group, And a combination of any of these.

That is, the polyimide may be prepared by preparing polyamic acid (PAA), followed by an imidization reaction in a subsequent curing process. The polyamic acid can be prepared according to a conventional production method. Specifically, the polyamic acid can be prepared by mixing a diamine in a solvent, adding dianhydride thereto, and then polymerizing the diamine. As the dianhydride, a wholly aromatic polyimide using an aromatic dianhydride can be preferably used.

At this time, in order that the main chain of the polyimide contains any one substituent selected from the group consisting of an amine group, a carboxyl group, a hydroxyl group, and a combination thereof, the polyimide or the polyamic acid is prepared, Alternatively, the hydrophilic substituent may be substituted for the main chain of the polyamic acid, or the polyimide may be prepared by using the diamine and / or the dianhydride containing the hydrophilic substituent, Can be prepared by polymerizing a comonomer containing a hydroxyl group together. The comonomer containing a hydroxy group may be selected from the group consisting of dianiline including a hydroxy group, diphenylurea including a hydroxy group, diamine including a hydroxy group, and combinations thereof.

When the main chain of the polyimide includes the hydrophilic substituent, the hydrophilic substituent may be contained in an amount of 0.01 to 0.1 mol%, preferably 0.01 to 0.08 mol%, more preferably 0.02 to 0.08 mol% based on the entire polyimide . If the content of the hydrophilic substituent is less than 0.01 mol%, hydrophilization may be insufficient due to the reduction of the hydrophilic group of the main chain of the polyimide. If the content of the hydrophilic substituent is more than 0.1 mol%, generation of side reaction and physical strength may be problematic.

As described above, when the nanofiber is made of a hydrophobic polymer such as polyimide or the like, in order to satisfy the saturated wetting time, water content, wettability by a wicking test, or contact angle, the surface of one or both surfaces of the nano- . When the nano-web is subjected to plasma treatment, a functional group having any hydrophilic property selected from the group consisting of a carboxyl group, a hydroxyl group, an amine group, and a combination thereof may be substituted on the surface of the nano-web.

Specifically, the plasma treatment may be performed using a gas capable of imparting a hydrophilic group to one or both sides of the nanoweb by using a low temperature plasma or a radio frequency (RF) plasma. The gas capable of imparting the hydrophilic group may be any one selected from the group consisting of ammonia gas, argon gas, oxygen gas, and combinations thereof. The flow rate of the gas capable of imparting the hydrophilic group may be 10-200 sccm , The power of the plasma may be 50 to 200 W, and the plasma treatment time may be 10 seconds to 5 minutes.

As described above, when the nanofiber is made of a hydrophobic polymer such as polyimide or the like, in order to satisfy the saturated wetting time, water content, wettability or contact angle by wicking test, the surface of one or both surfaces of the nano- Can be deposited. The inorganic material may be selected from the group consisting of anatase type titanium dioxide (TiO ₂ anatase), rutile type titanium dioxide (TiO ₂ rutile), brookite type titanium dioxide (TiO ₂ brookite), tin dioxide (SnO), zirconium dioxide (ZrO ₂ ) Al ₂ O ₃ , oxidized single wall carbon nanotubes, oxidized multiwall carbon nanotubes, oxidized graphite oxide, oxidized graphene, and combinations thereof.

The porous support is excellent in gas permeability and water permeability, and is excellent in heat resistance and chemical resistance, and is required to have heat resistance and chemical resistance, and is used as a filter medium for gas or liquid filters, a filter medium for dustproof masks, , Materials for filters such as ventilation for printers, materials for high-grade clothes such as moisture-proof tarpaulins, electro-chemical materials such as polymer electrolyte for fuel cell, secondary battery, separator of electrolytic device or capacitor, wound dressing, artificial blood vessel And can be used as a medical material such as a support, a bandage, a mask for cosmetics, and the like.

According to another embodiment of the present invention, there is provided a method of manufacturing a porous support, which comprises: electrospinning an electrospinning solution to produce a nanofabricated nanofibers integrated into a nonwoven fabric including a plurality of pores.

For example, when the nanofiber is formed of polyimide, which is a hydrophobic polymer, the method of producing the porous support comprises: preparing an electrospun solution by adding a diamine and a dianhydride to a solvent; electrospinning the electrospun solution Preparing a polyamic acid nanoweb integrated with nanofibers in the form of a nonwoven fabric including a plurality of pores, and preparing a polyimide nanoweb by imidizing the polyamic acid nanoweb.

The electrospinning solution is a solution containing monomers for forming the nanofibers. The monomers for forming the nanofibers exhibit excellent chemical resistance and are hydrophobic. In the environment of high humidity, A hydrocarbon-based polymer free from concern for shape deformation can be preferably used.

Examples of the hydrocarbon-based polymer include nylon, polyimide, polyaramid, polyetherimide, polyacrylonitrile, polyaniline, polyethylene oxide, polyethylene naphthalate, polybutylene terephthalate, styrene butadiene rubber, polystyrene, polyvinyl chloride, Polyolefins such as polyvinyl alcohol, polyvinylidene fluoride, polyvinyl butylene, polyurethane, polybenzoxazole, polybenzimidazole, polyamideimide, polyethylene terephthalate, polyethylene, polypropylene, copolymers thereof and mixtures thereof . Among these, polyimide having better heat resistance, chemical resistance, and shape stability is preferably used. Hereinafter, the case where the nanofiber is made of polyimide which is a hydrophobic polymer will be described in detail.

The monomers for forming the nanofibers may be used without particular limitation as long as they can form the hydrocarbon polymer. For example, a polyimide-containing nano-web is a polyimide precursor that is well soluble in an organic solvent. Polyamic acid (PAA) is used to prepare a polyamic acid nano-web, and imidization reaction in a subsequent curing process ≪ / RTI >

The polyamic acid nano-web may be prepared by a conventional method. Specifically, the polyamic acid nano-web may be prepared by mixing a diamine in a solvent, adding dianhydride thereto, and electrospinning the mixture.

Examples of the dianhydride include pyromellitic dianhydride (PMDA), 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride (3,3', 4,4'-benzophenonetetracarboxylic dianhydride, BTDA ), 4,4'-oxydiphthalic anhydride (ODPA), 3,4,3 ', 4'-biphenyltetracarboxylic acid anhydride (3,4,3', 4 ' -biphenyltetracarboxylic dianhydride (BPDA), bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride (SiDA), and mixtures thereof. Examples of the diamine include 4,4'-oxydianiline (ODA), 1,3-bis (4-aminophenoxy) benzene , RODA), p-phenylene diamine (p-PDA), o-phenylene diamine (o-PDA), and mixtures thereof. Prize Examples of the solvent for dissolving polyamic acid include m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO) Acetone, tetrahydrofuran (THF), chloroform, gamma -butyrolactone, and mixtures thereof.

The monomers for forming the nanofibers are preferably included in an amount of 5 to 20% by weight based on the total weight of the electrospinning solution. If the content of the monomers is less than 5% by weight, the fiber can not be formed or fibers having a uniform diameter can not be produced because the spinning does not proceed smoothly, whereas the content of the monomers exceeds 20% by weight If the discharge pressure increases suddenly, the radiation may not be produced or the fairness may deteriorate.

In step 2, the electrospun solution is spun to produce a nanobubbel precursor, i.e., a polyamic acid nanobeb. The radiation is not particularly limited in the present invention but may be electrospinning, electro-blown spinning, centrifugal spinning or melt blowing, Radiation can be used.

Hereinafter, the case of using electrospinning will be described in detail.

1 is a schematic view of a nozzle-type electrospinning device. 1, the electrospinning is performed by supplying the precursor solution to the nozzle 3 in a predetermined amount by using a metering pump 2 in a solution tank 1 in which the nanofibrous precursor solution is stored, The precursor nanofibers may be prepared by discharging the nanofibre precursor solution through the nanofiber precursor solution 3, forming a nanofiber precursor coagulated at the same time as the nanofiber precursor is scattered, and further concentrating the coagulated nanofiber precursor at the collector 4 to form precursor nanofibers of the porous support. have.

At this time, the electrospinning may be performed while increasing the positive charge density around the nozzle and increasing the negative charge density around the collector. As a result, polymer droplets are radiated and scattered, and at the same time, the effect of collecting into nanofibers can be obtained. The periphery of the nozzle or the periphery of the collector may mean a space within a radius of 10 cm from the surface of the nozzle or the collector, but is not particularly limited in the present invention.

Specifically, the positive charge density around the nozzle can be adjusted by providing a high voltage generator (not shown) capable of supplying a positive charge around the nozzle, and the negative charge density around the collector is controlled by a high voltage A generator (not shown) may be provided and controlled.

The degree of the increase of the positive charge density around the nozzle can be adjusted by supplying a positive charge around the nozzle at +10 to +100 kV, and the degree of increase of the negative charge density around the collector is set to be 0 to -100 kV . When the positive charge supply amount is less than +10 kV, the radiation force may be insufficient. When the positive charge supply amount is more than +100 kV, the electrical insulation may be broken. If the negative charge supply amount is less than 0, the potential difference may be insufficient. It can be destroyed.

At this time, the intensity of the electric field between the nozzle 3 and the collector 4 applied by the high voltage generating portion 6 and the voltage transmitting rod 5 is preferably 850 to 3,500 V / cm. If the electric field intensity is less than 850 V / cm, it is difficult to produce nanofibers of uniform thickness because the precursor solution is not continuously discharged. Also, since nanofibers formed after spinning can not be smoothly focused on the collector, The manufacture of the web may be difficult, and if the electric field strength exceeds 3,500 V / cm, the nanofibers can not be correctly placed on the collector 4, so that a nanobuck having a normal shape can not be obtained.

Through the spinning process, a nanofiber precursor having a uniform fiber diameter, preferably an average diameter of 0.01 to 5 탆, is produced, and the nanofiber precursor has a nonwoven fabric shape in a predetermined direction or randomly arranged.

In step 3, the nanofiber precursor of the nanobubbles precursor is cured.

In order to convert the nanofiber precursor into the nanofiber, a curing process is performed as an additional process for the nanofiber precursor. For example, if the nanofibrous precursor produced through electrospinning is made of polyamic acid, it is converted to polyimide through imidization during the curing process.

Accordingly, it is preferable that the temperature during the curing process is appropriately adjusted in consideration of the conversion rate of the nanofiber precursor. Concretely, it is preferable that the curing process is carried out at 80 to 650 ° C. When the curing temperature is lower than 80 ° C, the conversion rate is lowered. As a result, the heat resistance and chemical resistance of the nanoweb may be deteriorated. When the curing temperature is higher than 650 ° C, There is a possibility that the physical properties of the resin are deteriorated.

As described above, when the nanofiber is made of a hydrophobic polymer such as polyimide, in order to satisfy the saturated wetting time, water content, wettability or contact angle by wicking test, the nanoweb may include a hydrophilic additive have. That is, the nanofiber itself may include the hydrophilic additive, the hydrophilic additive may be impregnated into the pores of the nanoweb, and the hydrophilic additive may be coated on one or both surfaces of the nanoweb Lt; / RTI >

Specifically, when the nanofiber includes the hydrophilic additive, the hydrophilic additive may be further added to the electrospinning solution, followed by electrospinning. In this case, the hydrophilic additive may include 0.1 to 20 parts by weight, preferably 3 to 20 parts by weight, more preferably 5 to 20 parts by weight, of the hydrophilizing additive relative to 100 parts by weight of the monomer for producing the nanofibers .

If the amount of the hydrophilic additive is less than 0.1 parts by weight based on 100 parts by weight of the monomer for producing the nanofibers, the hydrophilic property may be insufficient and the wettability may be deteriorated to deteriorate the performance of the electrochemical device. In the spinning process, instability of nanofiber jets is increased and nonuniform fiber concentration occurs, which may cause problems when applied to a separator of an electrochemical device.

When the precursor solution containing the hydrophilic additive is spun, the instability of the jet is increased, and the nanofiber is uniformly focused on the collector. In this case, It is impossible to manufacture a nano-web having excellent quality. Therefore, when spinning the precursor solution containing the hydrophilic additive, a cation blower is installed in the radial environment to increase the cation density, and the base material of the collector surface should be exposed to the anion blower to increase the anion density of the collector base. Otherwise, a stable radiant jet can not be obtained and it may be difficult to produce a uniform and high-quality support.

In the case where the hydrophilic additive is impregnated into the pores of the nano web or the hydrophilic additive is coated on one surface or both surfaces of the nano web, the hydrophilic additive may be added to the hydrophilic additive solution prepared by adding the hydrophilic additive to the solvent. The porous support may be prepared by impregnating the nano-web with impregnation or by coating the surface of the nano-web with the solution of the hydrophilic additive.

In the method for impregnating the nanoweb with the hydrophilic additive solution, the nanoweb is dipped in the hydrophilic additive solution at room temperature for 5 to 30 minutes, and then dried in a hot air oven at 50 to 100 ° C. for 3 hours or more. , And performing the drying operation 2 to 5 times.

The method of coating the surface of the nanoweb with the hydrophilic additive solution may be various methods known in the art such as a laminating process, a spray process, a screen printing process, and a doctor blade process.

The hydrophilic additive solution may be at least one selected from the group consisting of anatase type TiO ₂ anatase, rutile type TiO ₂ rutile, brookite type TiO ₂ brookite, tin dioxide (SnO 2), zirconium dioxide (ZrO ₂ ), Aluminum oxide (Al ₂ O ₃ ), oxidized single-walled carbon nanotubes, oxidized multi-walled carbon nanotubes, oxidized graphite oxide, oxidized graphene, and combinations thereof, or Polyimide, polyamide, polyethylene terephthalate, polymethylmethacrylate, epoxy, and combinations thereof, wherein the organic hydrophilic polymer is selected from the group consisting of polyhydroxyethyl acrylate, polyhydroxyethyl acrylate, polyvinyl acetate, polyhydroxyethyl methacrylate, polyvinyl acetate, polyurethane, The additives were mixed with N-methyl-2-pyrrolidine (NMP), dimethylformamide (DMF), dimethylacetate Polyimide may be (dimethylacetamide, DMA), it added to any one of the solvents selected from the group consisting of dimethyl sulfoxide (dimethylsulfoxide, DMSO), and a combination thereof and prepared by mixing.

As described above, in order to satisfy the saturated wetting time, water content, wettability or contact angle by wicking test, the main chain of the polyimide may be an amine group, a carboxyl group, a hydrolyzate, And a hydrophilic substituent selected from the group consisting of a combination thereof.

That is, in order to produce a nanobeb made of a polyimide including the hydrophilic substituent group in the main chain, the porous support may be prepared by preparing the polyimide or the polyamic acid and then adding the polyimide or polyamic acid to the main chain of the polyimide or the polyamic acid. A polyimide is prepared by using a diamine and / or a dianhydride containing the hydrophilic substituent, or a comonomer including the hydroxy group in addition to the diamine and a dianhydride is added together Followed by polymerization.

The hydrophilic substituent may be substituted for the main chain of the polyimide or the polyamic acid by a treatment with an aqueous alkali solution such as KOH or NaOH to replace the carboxyl group and the amine group in a part of the main chain.

Further, the comonomer containing a hydroxy group may be any of those capable of polymerizing with the diamine and / or the dianhydride, including the hydrophilic substituent, for example, dianiline including a hydroxy group, Diphenylurea including a hydroxyl group, a diamine including a hydroxy group, and combinations thereof.

As described above, when the nanofiber is made of a hydrophobic polymer such as polyimide or the like, in order to satisfy the saturated wetting time, water content, wettability by a wicking test, or contact angle, the surface of one or both surfaces of the nano- . When the nano-web is subjected to plasma treatment, a functional group having any hydrophilic property selected from the group consisting of a carboxyl group, a hydroxyl group, an amine group, and a combination thereof may be substituted on the surface of the nano-web.

Specifically, the plasma treatment may be performed using a gas capable of imparting a hydrophilic group to one or both sides of the nanoweb by using a low temperature plasma or a radio frequency (RF) plasma. The gas capable of imparting the hydrophilic group may be any one selected from the group consisting of ammonia gas, argon gas, oxygen gas, and combinations thereof. The flow rate of the gas capable of imparting the hydrophilic group may be 10-200 sccm , The power of the plasma may be 50 to 200 W, and the plasma treatment time may be 10 seconds to 5 minutes.

As described above, when the nanofiber is made of a hydrophobic polymer such as polyimide or the like, an inorganic material is deposited on the surface of one or both surfaces of the nanoweb in order to satisfy the saturated wetting time, water content, wettability or contact angle by wicking test .

The deposited inorganic layer may be selected from the group consisting of anatase type TiO ₂ anatase, rutile type TiO ₂ rutile, boukite type TiO ₂ brookite, tin dioxide (SnO ₂ ), zirconium dioxide (ZrO ₂ ) Any precursor selected from the group consisting of aluminum oxide (Al ₂ O ₃ ), oxidized single wall carbon nanotube, oxidized multiwall carbon nanotube, oxidized graphite oxide, graphene oxide, and combinations thereof may be deposited by chemical vapor deposition ) Or physical vapor deposition (PVD) methods including sputtering. The deposition may be performed using a RF sputter or an evaporator, placing a substrate capable of imparting a hydrophilic group to the surface, and then treating the substrate at a temperature of 50 to 300 DEG C for 1 minute to 60 minutes.

According to another embodiment of the present invention, the reinforcing membrane comprises the porous support and the ion exchange polymer filled in the pores of the porous support.

The method of filling the ion exchange polymer in the pores of the porous support may include impregnation. The impregnation method may be performed by immersing the porous support in a solution containing an ion exchange polymer. In addition, the ion-exchange polymer may be formed by in-situ polymerization in the porous support after the relevant monomer or low molecular weight oligomer is immersed in the porous support.

The impregnation temperature and time may be influenced by various factors. For example, the thickness of the nano-web, the concentration of the ion exchange polymer, the type of the solvent, the concentration of the ion exchange polymer to be impregnated in the porous support, and the like can be influenced. However, the impregnation process may be performed at a temperature of 100 ° C or less at any point of the solvent, and more usually at a temperature of 70 ° C or less at room temperature. However, the temperature can not be higher than the melting point of the nanofiber.

The ion exchange polymer may be a cation exchange polymer having a cation exchange group such as a proton, or an anion exchange polymer having an anion exchange group such as a hydroxy ion, a carbonate or a bicarbonate.

The cation exchange group may be any one selected from the group consisting of a sulfonic acid group, a carboxyl group, a boronic acid group, a phosphoric acid group, an imide group, a sulfonimide group, a sulfonamide group and a combination thereof. Generally, the cationic exchange group may be a sulfonic acid group or a carboxyl group have.

Wherein the cation exchange polymer comprises the cation exchange group and a fluorine-based polymer containing fluorine in the main chain; Polyimides, polyacetals, polyethylenes, polypropylenes, acrylic resins, polyesters, polysulfones, polyethers, polyetherimides, polyesters, polyethersulfones, polyetherimides, polyamides, polyamides, Hydrocarbon polymers such as carbonates, polystyrene, polyphenylene sulfide, polyether ether ketone, polyether ketone, polyaryl ether sulfone, polyphosphazene or polyphenylquinoxaline; Partially fluorinated polymers such as polystyrene-graft-ethylene tetrafluoroethylene copolymer, or polystyrene-graft-polytetrafluoroethylene copolymer; Sulfonimide, and the like.

More specifically, when the cation exchange polymer is a hydrogen ion cation exchange polymer, the polymer may include a cation exchanger selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group and derivatives thereof in the side chain , Specific examples thereof include poly (perfluorosulfonic acid) containing sulfonic acid group, poly (perfluorocarboxylic acid), copolymer of tetrafluoroethylene and fluorovinyl ether containing sulfonic acid group, desulfurized sulfurized polyether A fluorine-based polymer including a ketone or a mixture thereof; Sulfonated polyimide (S-PI), sulfonated polyarylethersulfone (S-PAES), sulfonated polyetheretherketone (SPEEK), sulfonated polybenzyl ether A sulfonated polybenzimidazole (SPBI), a sulfonated polysulfone (S-PSU), a sulfonated polystyrene (S-PS), a sulfonated polyphosphazene, But is not limited thereto.

The anion exchange polymer is a polymer capable of transporting an anion such as a hydroxide ion, a carbonate or a bicarbonate. The anion exchange polymer is commercially available in the form of hydroxide or halide (generally chloride), and the anion exchange polymer Can be used for water purification, metal separation or catalytic processes, and the like.

As the anion exchange polymer, a metal hydroxide-doped polymer may be used. Specifically, metal hydroxide doped poly (ether sulfone), polystyrene, vinyl polymer, poly (vinyl chloride), poly (vinylidene fluoride) ), Poly (tetrafluoroethylene), poly (benzimidazole), poly (ethylene glycol), and the like.

The ion exchange polymer may be included in an amount of 50 to 99% by weight based on the total weight of the reinforcing film. If the content of the ion-exchange polymer is less than 50% by weight, the ionic conductivity of the reinforced membrane may be lowered. If the content of the ion-exchange polymer exceeds 99% by weight, the mechanical strength and dimensional stability of the reinforced membrane may be deteriorated .

The ion-exchange polymer may be filled in the pores of the porous support, and the coating layer may be formed on one or both surfaces of the porous support in the manufacturing process. If the coating layer of the ion-exchange polymer is formed on the surface of the porous support to a thickness exceeding 30 탆, the mechanical strength of the reinforcing membrane is preferably in the range of And the resistance loss can be increased by increasing the total thickness of the reinforcing film.

Since the reinforcing membrane has the structure in which the ion exchange polymer is filled in the pores of the porous support, it exhibits excellent mechanical strength of 40 MPa or more. As the mechanical strength is increased, the total thickness of the reinforced membrane can be reduced to 80 탆 or less. As a result, the ion conduction rate is increased and the resistance loss is reduced along with the material cost saving.

In addition, since the reinforcing membrane includes a porous support having excellent durability, and the binding force between the nanofibers constituting the porous support and the ion exchange polymer is excellent, the three-dimensional expansion of the reinforced membrane due to moisture can be suppressed, Is relatively low. In particular, the reinforcing membrane exhibits excellent dimensional stability of less than 5% when swollen in water. The dimensional stability is a physical property which is evaluated from the change in length before and after swelling when the reinforcing membrane is swelled in water according to the following formula (3).

&Quot; (3) "

Dimensional stability = [(length after swelling-length before swelling) / length before swelling] × 100

Since the reinforced membrane has excellent dimensional stability and ionic conductivity, it can be preferably used as a polymer electrolyte membrane for a fuel cell or a membrane for a reverse osmosis filter.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[ Manufacturing example  1: Preparation of porous support]

( Example  1-1)

100 parts by weight of PMDA and ODA and a PDA monomer and 5 parts by weight of an anatase-type nano TiO ₂ hydrophilizing additive were dissolved in a dimethylformamide solution to prepare 5 L of a 620 poise spinning solution at 12.5 wt%. The prepared spinning solution was transferred to a solution tank, and the solution was supplied to a spinning chamber having 26 nozzles and a high voltage of 49 kV through a metering gear pump to spin the polyamic acid nanoweb. At this time, the solution supply amount was 1.0 ml / min. In addition, cationic blowers and anion blowers were installed in the spinning chamber and the collector base, respectively, to increase the cation density in the spinning environment and to increase the anion density in the collector base.

Then, the polyamic acid nanoweb was thermally cured in a continuous curing furnace maintained at a temperature of 420 ° C. for 10 minutes while transferring the polyamic acid nanoweb in a roll-to-roll manner, thereby preparing a porous support composed of a polyimide nano-web.

( Example  1-2)

A porous support was prepared in the same manner as in Example 1-1 except that 0.1 part by weight of anatase-type nano-TiO ₂ was used as a hydrophilic additive.

( Example  1-3)

A porous support was prepared in the same manner as in Example 1-1 except that 20 parts by weight of anatase-type nano-TiO ₂ was used as a hydrophilic additive.

( Comparative Example  1-1)

100 monomers of PMDA, ODA and PDA monomers were dissolved in a dimethylformamide solution to prepare 5 L of a 620 poise spinning solution at 12.5 wt%. The prepared spinning solution was transferred to a solution tank, and the solution was supplied to a spinning chamber having 26 nozzles and a high voltage of 49 kV through a metering gear pump to spin the polyamic acid nanoweb. At this time, the solution supply amount was 1.0 ml / min. The polyamic acid nanoweb was thermally cured in a continuous curing furnace maintained at a temperature of 420 DEG C for 10 minutes to prepare a porous support composed of a polyimide nanoweb.

[ Test Example  1: Characteristic measurement of porous support]

The saturation hindrance time, moisture content, wettability and contact angle of the porous support prepared in the above Examples and Comparative Examples were measured, and the results are summarized in Table 1 below.

Example 1-1 Examples 1-2 Example 1-3 Comparative Example 1-1 Saturation Humidification Reach Time ¹⁾ 200 600 60 3600 Moisture content ^{2 )} 3.5 3.0 5.0 2.5 Wettability ^{3 )} 3 2 7 0 Contact angle ^{4 )} 45 80 25 113

1) Time to reach saturation humidification in seconds: KS K ISO 9073-6, textile - test method for nonwoven fabrics - Part 6: Absorption measurement method Under the liquid absorption time method, water is dropped at a height of 25 mm, Time is measured.

2) Moisture content (%): KS K 0221 Method of moisture measurement of textile: After reaching moisture equilibrium in fiber laboratory standard condition (KS K 0901) for 24 hours according to oven balance method, After drying for 30 minutes, the weight change rate is measured.

3) Wettability (cm): According to AATCC Test Method 197-2011, Vertical Wicking of Textiles (Option B, Measure distance at a given time), the specimens were immersed Measure the maximum wicking distance after 30 minutes.

4) Contact angle (°): The distilled water was filled into the syringe while keeping the temperature at 30 ° C and RH 40%. After dropping water droplets having a diameter of 3 mm on the separation membrane and waiting for the water droplets to spread for 5 minutes, Measure the contact angle.

Referring to Table 1, it can be seen that the porous membranes prepared in the Examples are superior in hydrophilicity to the membranes prepared in the Comparative Examples.

[ Manufacturing example  2 Preparation of porous support]

( Example  2-1)

PMDA, ODA and PDA monomers were dissolved in a dimethylformamide solution to prepare 5 L of a 620 poise spinning solution at 12.5 wt%. The prepared spinning solution was transferred to a solution tank, and the solution was supplied to a spinning chamber having 26 nozzles and a high voltage of 49 kV through a metering gear pump to spin the polyamic acid nanoweb. At this time, the solution supply amount was 1.0 ml / min.

Then, the polyamic acid nano-web was thermally cured in a continuous curing furnace maintained at a temperature of 420 ° C for 10 minutes to prepare a polyimide nano-web.

On the other hand, a hydrophilic additive, anatase type nano TiO ₂ , was added to dimethylformamide and stirred to prepare a hydrophilic additive solution. The prepared nanoweb was immersed in the prepared hydrophilic additive solution at room temperature for 10 minutes and then dried in a hot air oven at 80 DEG C for 3 hours or longer. Such immersion and drying operations were performed 2 to 5 times, Was impregnated into the nanoweb.

( Example  2-2)

The procedure of Example 2-1 was repeated except that the hydrophilic additive solution was coated on both surfaces of the nanoweb by spraying and then dried in Example 2-1 to prepare a porous support Respectively.

( Example  2-3)

PMDA, ODA and PDA monomers were dissolved in a dimethylformamide solution to prepare 5 L of a 620 poise spinning solution at 12.5 wt%. The prepared spinning solution was transferred to a solution tank, and the solution was supplied to a spinning chamber having 26 nozzles and a high voltage of 49 kV through a metering gear pump to spin the polyamic acid nanoweb. At this time, the solution supply amount was 1.0 ml / min.

Then, the polyamic acid nano-web was thermally cured in a continuous curing furnace maintained at a temperature of 420 ° C for 10 minutes to prepare a polyimide nano-web. Both surfaces of the polyimide nano- Oxygen gas was introduced into the plasma processing chamber at a flow rate of 150 sccm and then subjected to plasma treatment at 20 W for 5 minutes.

( Example  2-4)

PMDA, ODA and PDA monomers were dissolved in a dimethylformamide solution to prepare 5 L of a 620 poise spinning solution at 12.5 wt%. The prepared spinning solution was transferred to a solution tank, and the solution was supplied to a spinning chamber having 26 nozzles and a high voltage of 49 kV through a metering gear pump to spin the polyamic acid nanoweb. At this time, the solution supply amount was 1.0 ml / min.

Then, the polyamic acid nano-web was thermally cured in a continuous curing furnace maintained at a temperature of 420 ° C for 6 minutes to prepare a polyimide nano-web. The surface of both surfaces of the polyimide nanoweb was RF sputtered at a deposition power of 150 W, a specimen temperature of 200 ° C. and sputtering for 10 minutes to form a TiO ₂ inorganic layer.

[ Test Example  2: Characteristic measurement of porous support]

The saturation hindrance time, moisture content, wettability and contact angle of the porous support prepared in the above Examples and Comparative Examples were measured and the results are summarized in Table 2 below.

Example 2-1 Example 2-2 Example 2-3 Examples 2-4 Comparative Example 1-1 Saturation Humidification Reach Time ¹⁾ 250 280 10 300 3600 Moisture content ^{2 )} 3.3 3.6 5.0 3.8 2.5 Wettability ^{3 )} 4 4.5 15 6 0 Contact angle ^{4 )} 38 43 10 30 113

1) Time to reach saturation humidification in seconds: KS K ISO 9073-6, textile - test method for nonwoven fabrics - Part 6: Absorption measurement method Under the liquid absorption time method, water is dropped at a height of 25 mm, Time is measured.

2) Moisture content (%): KS K 0221 Method of moisture measurement of textile: After reaching moisture equilibrium in fiber laboratory standard condition (KS K 0901) for 24 hours according to oven balance method, After drying for 30 minutes, the weight change rate is measured.

3) Wettability (cm): According to AATCC Test Method 197-2011, Vertical Wicking of Textiles (Option B, Measure distance at a given time), the specimens were immersed Measure the maximum wicking distance after 30 minutes.

4) Contact angle (°): The distilled water was filled into the syringe while keeping the temperature at 30 ° C and RH 40%. After dropping water droplets having a diameter of 3 mm on the separation membrane and waiting for the water droplets to spread for 5 minutes, Measure the contact angle.

Referring to Table 2, it can be seen that the porous membrane prepared in the examples is superior in hydrophilicity to the membrane prepared in the comparative example.

[ Manufacturing example  3 Preparation of Porous Support]

( Example  3-1)

PMDA, ODA and PDA, and diphenyl Urea The monomers were dissolved in a dimethylformamide solution at a weight ratio of 50: 45: 5 to prepare 5 L of a 620 poise spinning solution at 12.5 wt%.

The prepared spinning solution was transferred to a solution tank, and the solution was supplied to a spinning chamber having 26 nozzles and a high voltage of 49 kV through a metering gear pump to spin the polyamic acid nanoweb. At this time, the solution supply amount was 1.0 ml / min.

Then, the polyamic acid nano-web was thermally cured in a continuous curing furnace maintained at a temperature of 420 ° C for 10 minutes to prepare a polyimide nano-web.

( Example  3-2)

PMDA, ODA and PDA monomers were dissolved in a dimethylformamide solution to prepare 620poise at 12.5% by weight. The prepared spinning solution was transferred to a solution tank, and the solution was supplied to a spinning chamber having 26 nozzles and a high voltage of 49 kV through a metering gear pump to spin the polyamic acid nanoweb. At this time, the solution supply amount was 1.0 ml / min.

Then, the polyamic acid nano-web was thermally cured in a continuous curing furnace maintained at a temperature of 420 ° C for 10 minutes to prepare a polyimide nano-web.

A 0.1 N KOH solution was sprayed on the surface of the polyimide nano-web by spraying for 1 second and then dried to replace the carboxyl group in the main chain of the polyimide with 0.02 mole%.

( Example  3-3)

PMDA, ODA and PDA monomers were dissolved in a dimethylformamide solution to prepare 620poise at 12.5% by weight. The prepared spinning solution was transferred to a solution tank, and the solution was supplied to a spinning chamber having 26 nozzles and a high voltage of 49 kV through a metering gear pump to spin the polyamic acid nanoweb. At this time, the solution supply amount was 1.0 ml / min.

Then, the polyamic acid nano-web was thermally cured in a continuous curing furnace maintained at a temperature of 420 ° C for 10 minutes to prepare a polyimide nano-web.

A 0.1 N NaOH solution was sprayed on the surface of the polyimide nano-web by spraying for 1 second and then dried to replace the carboxyl group in the main chain of the polyimide with 0.01 mol%.

[ Test Example  3: Characteristic measurement of porous support]

The saturation damping time, moisture content, wettability and contact angle of the porous support prepared in the above Examples and Comparative Examples were measured and the results are summarized in Table 3 below.

Example 3-1 Example 3-2 Example 3-3 Comparative Example 1-1 Saturation Humidification Reach Time ¹⁾ 500 580 600 3600 Moisture content ^{2 )} 3.1 3.3 3.2 2.5 Wettability ^{3 )} 2.5 2.9 2.8 0 Contact angle ^{4 )} 48 42 44 113

1) Time to reach saturation humidification in seconds: KS K ISO 9073-6, textile - test method for nonwoven fabrics - Part 6: Absorption measurement method Under the liquid absorption time method, water is dropped at a height of 25 mm, Time is measured.

2) Moisture content (%): KS K 0221 Method of moisture measurement of textile: After reaching moisture equilibrium in fiber laboratory standard condition (KS K 0901) for 24 hours according to oven balance method, After drying for 30 minutes, the weight change rate is measured.

3) Wettability (cm): According to AATCC Test Method 197-2011, Vertical Wicking of Textiles (Option B, Measure distance at a given time), the specimens were immersed Measure the maximum wicking distance after 30 minutes.

4) Contact angle: The distilled water was charged into the syringe while maintaining the temperature at 30 ° C and RH 40%. Drops of water 3 mm in diameter were dropped on the separation membrane, and the water droplets spread for 5 minutes. After 5 minutes, .

Referring to Table 3, it can be seen that the porous membrane prepared in the examples is superior in hydrophilicity to the membrane prepared in the comparative example.

[ Manufacturing example  4: Reinforced membrane  Produce]

5% by weight of a Nafion solution together with the porous support prepared in the above Preparation Examples 1 to 3 was put into a Petri dish so that 0.06 g of Nafion per unit area (cm ² ) of the web could be impregnated, And dried at 60 DEG C for 4 hours or more to prepare a reinforced membrane.

[ Test Example  4]

Each of the reinforcing membranes prepared in Preparation Example 4 was immersed in 1 molar sulfuric acid solution so that the hydrophilic groups were sufficiently activated, and the surface was cleaned with ultra-pure water to prepare conductivity measurement samples. Then, 90% At 25 DEG C and 80 DEG C, respectively.

The reinforced membrane prepared in Preparation Example 4 was dried for 6 hours or more in an oven at 60 ° C and stored for 2 hours at 80 ° C in hot water. The resultant reinforced membrane was subjected to five times repeatedly, The tensile strength was measured and the occurrence of desorption was measured.

In order to evaluate the morphological stability of the reinforced membrane prepared in Preparation Example 4, the reinforced membrane was dried in a hot air oven at a temperature of 50 ° C for 6 hours and immersed in ultrapure water for 24 hours to measure the dimensional change of the reinforced membrane.

The measurement results are shown in Table 4 below.

Ion conductivity (Sm ^-1 ) Tensile Strength (MPa) Tally Dimensional change ratio (%) 25 ℃ 80 ℃ Evaluation game After 5 times X Y Example 1-1 0.07 0.08 47 45 Tally X One One Examples 1-2 0.06 0.07 40 33 Tally X 0.5 0.5 Example 1-3 0.09 0.10 49 49 Tally X 0.1 0.1 Example 2-1 0.07 0.08 46 43 Tally X 0.5 0.5 Example 2-2 0.07 0.08 46 43 Tally X 0.5 0.5 Example 2-3 0.08 0.09 40 35 Tally X 1.0 1.0 Examples 2-4 0.07 0.08 43 43 Tally X 0.5 0.5 Example 3-1 0.07 0.08 41 40 Tally X 0.5 0.5 Example 3-2 0.07 0.08 40 35 Tally X 0.5 0.5 Example 3-3 0.07 0.08 40 35 Tally X 0.5 0.5 Comparative Example 1-1 0.06 0.07 40 30 Tally 1.0 1.0 Control Example ^{1 )} 0.09 0.10 36 26 Tally 10.0 10.0

1) Control Example: A polymer electrolyte membrane prepared by immersing Nafion 117 membrane of DuPont in ultrapure water for 3 hours or more to make water in the membrane sufficiently present.

As shown in Table 4, the reinforced membranes of the Examples and Comparative Examples showed comparable hydrogen ion conductivity at 25 캜, as compared with the fluorinated reinforced membranes of the comparative examples, which are known to exhibit excellent hydrogen ion conductivity. However, at a high temperature of 80 占 폚, the reinforced membrane of the Example exhibited the same level of hydrogen ion conductivity as that of the fluorinated reinforced membrane of the Control Example, while the reinforced membrane of Comparative Example exhibited significantly lower ion conductivity than the fluorinated reinforced membrane of the Control Example.

In addition, it can be seen that the reinforced membrane of the example exhibits remarkably improved morphological stability as compared with the electrolyte membrane of the fluorine-based polymer which is conventionally known to exhibit excellent hydrogen ion conductivity.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

1: solution tank
2: metering pump
3: Nozzle
4: Collector
5: Voltage transferring rod
6: High voltage generator

Claims (29)

Wherein the polyimide nanofibers comprise a nanoweb integrated into a nonwoven fabric comprising a plurality of pores,
Wherein the main chain of the polyimide comprises a hydrophilic substituent. The method according to claim 1,
Wherein the hydrophilic substituent comprises any substituent selected from the group consisting of an amine group, a carboxyl group, a hydroxyl group, and combinations thereof. The method according to claim 1,
Wherein the polyimide is prepared by imidizing a polyamic acid prepared by polymerizing a comonomer comprising diamine, dianhydride, and a hydroxy group. The method of claim 3,
Wherein the comonomer containing a hydroxy group is any one selected from the group consisting of dianiline including a hydroxy group, diphenylurea including a hydroxy group, diamine including a hydroxy group, and combinations thereof. The method according to claim 1,
Wherein the saturation hindrance time of the nano-web is from 1 second to 5 minutes. The method according to claim 1,
Wherein the nano-web has a moisture content of 3.0% or more. The method according to claim 1,
Wherein the nano-web has a wettability of 2 to 15 cm by a wicking test. The method according to claim 1,
Wherein the nano-web has a contact angle of 90 DEG or less. The method according to claim 1,
Wherein the nanofiber comprises 0.1 to 20 parts by weight of a hydrophilic additive to 100 parts by weight of the nanofiber polymer. The method according to claim 1,
Wherein a hydrophilic additive is impregnated in the pores of the nano-web. The method according to claim 1,
Wherein a hydrophilic additive is coated on one surface or both surfaces of the nano web. 12. The method according to any one of claims 9 to 11,
The hydrophilic additive may be selected from the group consisting of anatase type titanium dioxide (TiO ₂ anatase), rutile type titanium dioxide (TiO ₂ rutile), brookite type titanium dioxide (TiO ₂ brookite), tin dioxide (SnO ₂ ), zirconium dioxide Wherein the porous support is any one selected from the group consisting of aluminum (Al ₂ O ₃ ), oxidized single wall carbon nanotube, oxidized multiwall carbon nanotube, oxidized graphite oxide, graphene oxide, and combinations thereof. 12. The method according to any one of claims 9 to 11,
Wherein the hydrophilic additive is selected from the group consisting of polyhydroxyethyl methacrylate polyvinyl acetate, polyurethane, polydimethylsiloxane, polyimide, polyamide, polyethylene terephthalate, polymethyl methacrylate, epoxy, One is a porous support. 12. The method according to any one of claims 9 to 11,
Wherein the hydrophilic additive is a nano-hydrophilic additive having an average particle diameter of 0.1 to 1 占 퐉. The method according to claim 1,
Wherein the surface of the one or both surfaces of the nano-web is plasma-treated. The method according to claim 1,
Wherein an inorganic material is deposited on one surface or both surfaces of the nano web. 17. The method of claim 16,
The inorganic material may be selected from the group consisting of anatase type titanium dioxide (TiO ₂ anatase), rutile type titanium dioxide (TiO ₂ rutile), brookite type titanium dioxide (TiO ₂ brookite), tin dioxide (SnO), zirconium dioxide (ZrO ₂ ) Al ₂ O ₃ ), an oxidized single-walled carbon nanotube, an oxidized multi-walled carbon nanotube, an oxidized graphite oxide, an oxidized graphene, and a combination thereof. Adding diamine and dianhydride to a solvent to prepare an electrospinning solution,
Preparing a polyamic acid nano-web by integrating the nanofibers in the form of a nonwoven fabric including a plurality of pores, and
And imidizing the polyamic acid nano-web to prepare a polyimide nano-web,
Wherein the main chain of the nanofibers contained in the polyimide nanoweb is substituted with any one hydrophilic substituent selected from the group consisting of an amine group, a carboxyl group, a hydroxyl group, and a combination thereof. 19. The method of claim 18,
Wherein the diamine or the dianhydride is substituted with any one substituent selected from the group consisting of an amine group, a carboxyl group, a hydroxyl group, and a combination thereof. 19. The method of claim 18,
Further comprising the step of preparing the polyimide nanoweb or the polyamic acid nanoweb and then replacing the hydrophilic substituent with the main chain of the polyimide or the polyamic acid. 19. The method of claim 18,
Wherein a comonomer containing a hydroxy group is further added to the electrospinning solution. 19. The method of claim 18,
Wherein a hydrophilic additive is further added to the electrospinning solution. 19. The method of claim 18,
And impregnating a hydrophilic additive into the pores of the nanoweb. 19. The method of claim 18,
Further comprising coating a hydrophilic additive on one surface or both surfaces of the nano web. 19. The method of claim 18,
Further comprising the step of plasma-treating one or both surfaces of the nano-web. 26. The method of claim 25,
Wherein the plasma treatment is performed with a gas capable of imparting a hydrophilic group to one or both surfaces of the nanoweb by using a low-temperature plasma or a radio frequency (RF) plasma. 19. The method of claim 18,
Further comprising the step of depositing an inorganic material on one or both surfaces of the nano web. 28. The method of claim 27,
Wherein the method of depositing the inorganic material is sputtering. A porous support according to claim 1, and
The ion exchange polymer filling the pores of the porous support
≪ / RTI >

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