WO2015130066A1

WO2015130066A1 - Porous support, method for manufacturing same, and reinforced membrane comprising same

Info

Publication number: WO2015130066A1
Application number: PCT/KR2015/001789
Authority: WO
Inventors: 김성진; 오흥렬; 이용환; 노환권; 김철기; 최정영; 박준영; 백지숙
Original assignee: 코오롱패션머티리얼 (주)
Priority date: 2014-02-25
Filing date: 2015-02-25
Publication date: 2015-09-03
Also published as: JP2017510722A; KR20150101039A; US20170030009A1

Abstract

The present invention relates to a porous support, a method for manufacturing the same, and a reinforced membrane comprising the same, the porous support comprising a nanoweb in which nanofibers are accumulated in the form of a nonwoven fabric including a plurality of pores, wherein the nanoweb has a moisture saturation time of 1 second to 600 seconds. The porous support not only has excellent durability, heat resistance, and chemical resistance while exhibiting excellent air permeability and water permeability, but also has good hydrophilicity.

Description

Porous support, preparation method thereof, and reinforcing film including the same

The present invention relates to a porous support, a method for preparing the same, and a reinforcing membrane including the same, and more particularly, a porous support having excellent hydrophilicity and excellent hydrophilicity, as well as excellent air permeability and water permeability. It relates to a manufacturing method, and a reinforcing film including the same.

Nanofiber has a wide surface area and excellent porosity, and is used for various purposes such as water purification filters, air purification filters, composite materials, battery separators, and the like, and may be particularly useful for reinforcement composite membranes used in fuel cells for automobiles.

Fuel cells are electrochemical devices that run on hydrogen and oxygen as fuels, and are now becoming environmentally friendly because their products are pure water and reusable heat. In addition, due to its simple operation, high power density and noise, it is widely used as a power source for home, automobile, and power generation.

Fuel cells may be classified into alkali electrolyte fuel cells, direct oxidation fuel cells, and polymer electrolyte membrane fuel cells (PEMFC), depending on the type of electrolyte membrane. Among them, the polymer electrolyte membrane fuel cell is a hydrogen ion ( H ⁺ ) can be operated at room temperature 20 due to the generation of electricity from the anode (anode) to the cathode (cathode), has the advantage that the activation time is very short compared to other fuel cells. .

The polymer electrolyte membrane fuel cell includes an electricity generating unit including a membrane electrode assembly (MEA) and a separator (also called a bipolar plate) having an anode and a cathode formed therebetween with a polymer electrolyte membrane therebetween; And a fuel supply unit supplying fuel to the electricity generation unit, and an oxidant supply unit supplying an oxidant such as oxygen or air to the electricity generation unit.

The polymer electrolyte membrane may be divided into a single membrane made of a polymer such as a fluorine-based hydrocarbon or a hydrocarbon-based conductor as a conductor of hydrogen ions, and a composite membrane used by combining an organic-inorganic material or a porous support with the polymer. In the case of a single membrane, DuPont's Nafion, which is a perfluorinated polymer, is most used, but has a disadvantage in that the membrane resistance is high due to its high price, low mechanical shape stability, and thick thickness.

To overcome these shortcomings, studies on composite membranes with enhanced mechanical and morphological stability have been actively conducted. Among them, the pore-filled membranes in which the porous support is impregnated with ionic conductors are not only inexpensive but also have performance mechanical and morphological stability. There is much research being done.

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

[Preceding technical literature]

(Patent Document 1) Korean Patent Publication No. 2011-0120185 (2011.11.03 published)

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

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

Still another object of the present invention is to provide a reinforcing film including the porous support.

According to one embodiment of the present invention, the nanofibers include a nanoweb integrated into a nonwoven fabric including a plurality of pores, and provide a porous support having a saturation moisture arrival time of 1 to 600 seconds.

The nanoweb may have a moisture content of 3.0 wt% or more.

The nanoweb may have a wettability of 2 to 15 cm by a wicking test.

The nanoweb may have a contact angle of 90 ° or less.

The nanofibers may include 0.1 to 20 parts by weight of a hydrophilization additive based on 100 parts by weight of the nanofiber polymer.

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

Hydrophilization additives may be coated on one or both surfaces of the nanoweb.

The hydrophilization additive is 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 ), It may be any one selected from the group consisting of aluminum oxide (Al ₂ O ₃ ), oxidized single-walled carbon nanobubbles, oxidized multi-walled carbon nanotubes, graphite oxide, graphene oxide and combinations thereof.

The hydrophilic additive is selected from the group consisting of polyhydroethyl methacrylate, polyvinylacetate, polyurethane, polydimethylsiloxane, polyimide, polyamide, polyethylene terephthalate, polymethyl methacrylate, epoxy, and combinations thereof. It can be either.

The average particle diameter of the hydrophilic additive may be a nano hydrophilic additive of 0.005 to 1㎛.

The nanofibers may be polyimide nanofibers.

The main chain of the polyimide may include any substituent selected from the group consisting of an amine group, a carboxyl group, a hydroxyl group, and a combination 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 including the hydroxy group may be any one selected from the group consisting of dianiline including a hydroxy group, diphenyl urea including a hydroxy group, diamine including a hydroxy group, and a combination thereof.

One or both surfaces of the nanoweb may be plasma treated.

Inorganic materials may be deposited on one or both surfaces of the nanoweb.

The inorganic material is 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 ), aluminum oxide ( Al ₂ O ₃ ), single-walled oxide carbon nanobubble, multi-walled carbon nanotube oxide, graphite oxide, graphene oxide and a combination thereof may be any one selected from the group.

According to another embodiment of the present invention, adding diamine and dianhydride to a solvent to prepare an electrospinning solution, electrospun the prepared electrospinning solution in the form of a nonwoven fabric in which the nanofibers comprise a plurality of pores Preparing an integrated polyamic acid nanoweb, and imidizing the polyamic acid nanoweb to produce a polyimide nanoweb, wherein the saturation moisture arrival time of the polyimide nanoweb is 1 second to 600 seconds. Provided are methods for preparing a phosphorous porous support.

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

The main chain of the nanofibers included in the polyimide nanoweb may be substituted with any one substituent selected from the group consisting of an amine group, a carboxyl group, a hydroxyl group and a combination thereof.

According to another embodiment of the present invention, the step of electrospinning the electrospinning solution to produce a nanoweb integrated nanofibers in the form of a non-woven fabric comprising a plurality of pores, the saturation moisture arrival time of the nanoweb It provides a method for producing a porous support that is from 1 second to 600 seconds.

Hydrophilic additives may be further added to the electrospinning solution.

The method may further include impregnating a hydrophilization additive in the pores of the nanoweb.

The method may further include coating a hydrophilization additive on one or both surfaces of the nanoweb.

Plasma treatment of one or both surfaces of the nanoweb.

The plasma treatment condition may be to treat with a gas that can impart a hydrophilic group to one or both surfaces of the nanoweb using a low-temperature plasma or radio frequency (RF) plasma.

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

The method of depositing the inorganic material may be sputtering.

According to another embodiment of the present invention, there is provided a reinforcing film including the porous support and an ion exchange polymer filling the pores of the porous support.

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

The porous support according to the present invention not only has excellent air permeability and water permeability, but also has excellent durability, heat resistance and chemical resistance, and excellent hydrophilicity.

1 is a schematic diagram of a nozzle type electrospinning apparatus.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present invention, the terms 'comprise' or 'have' are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

As used herein, the term "nano" means nanoscale and includes a size of 1 μm or less.

As used herein, the term "diameter" means the length of a short axis passing through the center of the fiber, and the "length" means the length of the long axis passing through the center of the fiber.

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

The nanofibers have excellent chemical resistance, and can be preferably used hydrocarbon-based polymers which have hydrophobicity and are free of morphological changes due to moisture in a high humidity environment. Specifically, the hydrocarbon-based polymer may be nylon, polyimide, polyaramid, polyetherimide, polyacrylonitrile, polyaniline, polyethylene oxide, polyethylene naphthalate, polybutylene terephthalate, styrene butadiene rubber, polystyrene, polyvinyl chloride, Polyvinyl alcohol, polyvinylidene fluoride, polyvinyl butylene, polyurethane, polybenzoxazole, polybenzimidazole, polyamideimide, polyethylene terephthalate, polyethylene, polypropylene, copolymers thereof, and mixtures thereof The polyimide excellent in heat resistance, chemical resistance, and morphological stability can be used preferably among these, It can select from the group which consists of these.

The porous support includes an aggregate of nanofibers, ie, nanowebs, in which nanofibers prepared by electrospinning are randomly arranged. In this case, considering the porosity and thickness of the nanoweb, the average diameter of 40 to 5,000nm when the diameter of 50 fibers were measured using an electron scanning microscope (Scanning Electron Microscope, JSM6700F, JEOL), and calculated from the average. It is preferred to have a diameter. If the average diameter of the nanofibers is less than 40nm, the mechanical strength of the porous support may be lowered. If the average diameter of the nanofibers exceeds 5,000nm, the porosity may be significantly decreased and the thickness may be thickened.

The nanoweb may be made of the nanofibers as described above, and may have a porosity of 50% or more. As described above, the porosity of 50% or more increases the specific surface area of the porous support, so that the electrolyte is easily impregnated when applied as a separator, and as a result, the efficiency of the battery can be improved. On the other hand, the nanoweb preferably has a porosity of 90% or less. If the porosity of the nanoweb exceeds 90%, morphological stability may be lowered, and thus the subsequent process may not proceed smoothly. The porosity may be calculated by the ratio of the air volume to the total volume of the porous support according to Equation 1 below. In this case, the total volume is calculated by measuring the width, length, and thickness of the sample by preparing a rectangular shape, and the air volume can be obtained by subtracting the volume of the polymer inverted from the density after measuring the mass of the sample.

[Equation 1]

Porosity (%) = (air volume in nanoweb / total volume of porous support) × 100

In addition, the nanoweb may have an average thickness of 5 to 50㎛. If the thickness of the nanoweb is less than 5㎛ the mechanical strength and dimensional stability can be significantly reduced when applied as a separator, while if the thickness exceeds 50㎛ the resistance loss increases when applied to the separator, light weight and integration may fall have. More preferred thickness of the nanoweb is in the range of 10 to 30 mu m.

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

In addition, the nanoweb may have a weight average molecular weight in the range as described above, and as the polymer precursor is converted into a polymer under optimal curing conditions, the heat resistance may be 180 ° C. or higher, preferably 300 ° C. or higher. If the heat resistance of the nanoweb is less than 180 ° C., the heat resistance may be easily deformed at high temperatures as the heat resistance thereof decreases, and thus, the electrochemical device manufactured using the nanoweb may degrade performance. In addition, when the heat resistance of the nanoweb is reduced, the shape is deformed by abnormal heat generation, the performance is degraded, and if severe, it may cause a problem that bursts and explodes.

The nanoweb may be chemically insoluble in an organic solvent at room temperature (20 ° C.) to 100 ° C. The organic solvent may be a conventional organic solvent such as NMP, DMF, DMAc, DMSO, THF, and the like.

The nanoweb may have a strain of 10% or less, preferably 5% or less. The strain may be measured as an average of the transverse, longitudinal strain before and after leaving the nanoweb at 100 ℃ length 100 mm specimen 24 hours at 200 ℃. When the strain exceeds 10% by length, the shape may be modified under dimensional stability and high temperature environment of the support.

When the nanoweb is made of polyimide, the imide conversion may be 90% or more, and preferably 99% or more. The imide conversion rate can be measured by measuring the infrared spectra with respect to the nano web, calculating the ratio of the p- substituted CH absorbance already de CN absorbance at about 1500cm ^-1 1375cm ^-1. If the imide conversion is less than 90%, due to the unreacted material, it is not possible to secure the physical property degradation and form stability.

The nanoweb may have an air permeability of 50 to 250lpm, preferably 100 to 150lpm. The air permeability can be measured by the ISO 9237 method. If the air permeability is less than 50lpm, it may be difficult to absorb the electrolyte, and if it exceeds 250lpm, it may not include the electrolyte sufficiently.

The nanoweb is excellent in hydrophilicity, the saturation moisture reaching time may be 1 second to 600 seconds, preferably 1 second to 300 seconds, more preferably 1 second to 180 seconds, even more preferably 1 second to 60 seconds Can be. The saturation moisture arrival time is measured according to KS K ISO 9073-6, Textile-Non-Woven Fabric Test Method-Part 6: Liquid Absorption Time Method of Absorption Measurement Standard. Can be.

When the saturation moisture arrival time is within the above range, the nano-web may be impregnated with an ion exchange polymer, so that the ion-exchange polymer may be uniformly impregnated throughout the pores of the nanoweb when the reinforcing film is manufactured. In addition, when the hydrophilicity of the nanoweb is increased, a hydrophilization channel may be further formed when the reinforcing film is used as a membrane for a fuel cell, thereby improving ion conductivity.

The nanoweb may have an electrolyte absorption capacity of 10 to 60% by weight, preferably 30 to 40% by weight. The electrolyte absorption capacity was 70/30 (v) of ethyl methyl carbonate and ethylene carbonate based on KS K ISO 9073-6, Textile-Non-Woven Test Method-Part 6: Liquid Hygroscopic Capacity Method of Absorption Measurement Standard. / v) the mixture may be dropped at a height of 25 mm for 60 seconds, the mixture is drained vertically for 120 seconds, and then the weight of the nanoweb may be measured and calculated as in Equation 2 below. When the electrolyte absorption capacity is less than 10% by weight, the electrolyte absorption may be insufficient and battery performance may not be sufficiently expressed, and when the electrolyte absorption capacity is greater than 60% by weight, deterioration of the physical properties of the support may occur.

[Equation 2]

Electrolyte Absorption Capacity (%) = (W1-W) / W × 100

In Equation 2, W is the weight of the nanoweb before the electrolyte absorption, W1 is the weight of the nanoweb after the electrolyte absorption.

The nanoweb may have a moisture regain of 3.0 wt% or more, preferably 3.0 to 5.0 wt%, and more preferably 3.1 to 5.0 wt%. The moisture content is measured by measuring the moisture (O: weight of the specimen) after reaching the water equilibrium in the fiber laboratory standard state (KS K 0901) for 24 hours according to the moisture measurement method of KS K 0221 textile: oven balance method After drying for 1 hour and 30 minutes at 105 to 110 ° C., the weight (D: weight of the dried specimen) may be measured and calculated by Equation 3 below.

[Equation 3]

Moisture Content (wt%) = (O-D) / D x 100

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

The nanoweb may have a wettability of 2 to 15 cm by a wicking test, preferably 2.1 to 15 cm, and more preferably 3 to 15 cm. The wicking test is based on the US AATCC Test Method 197-2011, Vertical Wicking of Textiles B (Option B, Measure distance at a given time), 30 minutes after immersing the specimen It can measure by the method of measuring the later wicking maximum distance. When the wettability of the wicking test is less than 2 cm, the ion conductor and the support may be detached from the fuel cell operating environment, the operating time may be delayed in low humidity conditions, or the physical shape stability may be lowered, and it may exceed 15 cm. In the fuel cell operating environment, the durability of the ion conductor may be reduced by swelling of the ion conductor, or the ion conductor and the support may be detached.

The nanoweb may have a contact angle of 90 ° or less, preferably 1 to 50 °, and more preferably 5 to 35 °. The contact angle was filled with a syringe with distilled water while maintaining a 30 ° C and 40% RH to drop a droplet of 3mm diameter on the nanoweb, waiting for the water droplets to spread for 5 minutes, after 5 minutes to form a separator and water droplets The contact angle can be measured. When the contact angle is less than 1 °, the wettability of the nanoweb may be excellent, but it may be difficult to manufacture high quality nanoweb due to an excessive amount of additives in the spinning process, and when the contact angle exceeds 90 °, the wettability is inferior to the separator of the electrochemical device. If used, it may be difficult to express sufficient performance.

When the nanofibers are made of a hydrophobic polymer such as polyimide, there is an advantage of excellent heat resistance, chemical resistance, and morphological stability, but lack of hydrophilic properties to uniformly increase the ion conductive polymer throughout the pores of the nanoweb. Can not be impregnated, and the formation of the hydrophilic channel may be insufficient, leading to a decrease in ion conductivity. Accordingly, in order to satisfy the saturation moisture arrival time, moisture content, wettability or contact angle by the wicking test, the nanoweb made of the hydrophobic polymer is required to be hydrophilized. The said hydrophilization treatment can be applied as long as it is a conventional method which can improve the hydrophilicity of the said nanoweb, and is not specifically limited in this invention.

As an example of the hydrophilization treatment method of the nanoweb, the nanoweb may include a hydrophilization additive. That is, the nanofibers themselves may include the hydrophilization additive, the hydrophilic additive may be impregnated in the pores of the nanoweb, the hydrophilic additive is coated on the surface of one or both surfaces of the nanoweb It may be.

Specifically, when the nanofibers include the hydrophilic additive, the nanofibers may contain 0.1 to 20 parts by weight of hydrophilization additive, preferably 0.5 to 20 parts by weight, more preferably 1 to 1, based on 100 parts by weight of the nanofiber polymer. It may be included in 2 parts by weight.

When the amount of the hydrophilization additive is less than 0.1 parts by weight with respect to 100 parts by weight of the nanofiber polymer, the hydrophilic performance is insufficient, so that the wettability may be degraded, and the performance of the electrochemical device may be lowered. Instability of the nanofiber jet (jet) is increased and non-uniform fiber focusing may be a problem when applied to the membrane of the electrochemical device.

When the hydrophilization additive is impregnated in the pores of the nanoweb, or when the hydrophilic additive is coated on the surface of one or both surfaces of the nanoweb, the nanoweb may contain 0.1% of the hydrophilization additive based on 100 parts by weight of the nanoweb. To 20 parts by weight, preferably 3 to 20 parts by weight, more preferably 5 to 20 parts by weight.

When the amount of the hydrophilization additive is less than 0.1 parts by weight with respect to 100 parts by weight of the nanoweb, the hydrophilic performance is insufficient, the wettability may be reduced, and the performance of the electrochemical device may be lowered. Instability of fiber jets and non-uniform fiber convergence can lead to problems when applied to separators in electrochemical devices.

The nanoweb has excellent wettability as the hydrophilic additive is included, and when used as a separator for an electrochemical device, the nanoweb may have excellent wettability with respect to an electrolyte, thereby improving efficiency of a battery. In addition, the porous support is excellent in durability, heat resistance and chemical resistance to maintain the performance of the electrochemical device even in harsh operating conditions.

The hydrophilic additive may be an inorganic or organic hydrophilic additive. The inorganic hydrophilic additives undergo oxidation and / or reduction reactions, i.e., electrochemical reactions, with the positive or negative electrode current collectors in the operating voltage range of the electrochemical device (e.g., 0 to 5 V on Li / Li ⁺ basis for lithium secondary batteries). It does not occur, does not impair the electrical conductivity, and if it can withstand the manufacturing process in the production of nanofibers including the same is not particularly limited.

For example, the inorganic hydrophilization additive may be 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 ), aluminum oxide (Al ₂ O ₃ ), single-walled oxide carbon nanobubble, multi-walled carbon nanotube oxide, graphite oxide, graphene oxide and any combination thereof may be selected from the group consisting of Preferably TiO ₂ .

In addition, the organic hydrophilic additive may also be subjected to oxidation and / or reduction reactions, i.e., electrochemical, with a positive or negative electrode current collector in the operating voltage range of the electrochemical device (e.g., 0 to 5 V on Li / Li ⁺ basis for lithium secondary batteries). There is no particular limitation as long as it does not cause a reaction and does not impair current conduction, and can withstand a manufacturing process in manufacturing a nanofiber including the same.

For example, the organic hydrophilic additive may include polyhydroethyl methacrylate, polyvinylacetate, polyurethane, polydimethylsiloxane, polyimide, polyamide, polyethylene terephthalate, polymethylmethacrylate, epoxy, and combinations thereof. It may be any one selected from the group consisting of.

The hydrophilic additive may be a nano hydrophilic additive, and thus the average particle diameter of the hydrophilic additive may be 0.005 to 1 ㎛, preferably 0.005 to 0.8 ㎛, more preferably 0.005 to 0.5 ㎛. When the average particle diameter of the nano-hydrophilic additive is less than 0.005㎛ the hydrophilic effect may be inhibited or difficult to handle due to the aggregation of the nano-hydrophilized particles, when the nano-hydrophilic additive exceeds 1㎛ physical tensile strength of the support is lowered, elongation at break Can be reduced.

As described above, when the nanofiber is made of a polyimide which is a hydrophobic polymer, the main chain of the polyimide may be an amine group, a carboxyl group, or a hydroxyl group in order to satisfy the saturation moisture arrival time, moisture content, wettability or contact angle by a wicking test. And it may include any one hydrophilic substituent selected from the group consisting of a combination thereof.

That is, the polyimide may be prepared through the imidization reaction in a subsequent curing process after preparing a polyamic acid (PAA). The polyamic acid may be prepared according to a conventional manufacturing method, specifically, diamine may be prepared by mixing diamine in a solvent, adding dianhydride thereto, and polymerizing the diamine. Aromatic diamine, and as the dianhydride, a wholly aromatic polyimide using an aromatic dianhydride can be preferably used.

In this case, the polyimide after preparing the polyimide or the polyamic acid to include any substituent selected from the group consisting of the amine group, carboxyl group, hydroxy group and combinations thereof Or substituting the hydrophilic substituent on the main chain of the polyamic acid, preparing the polyimide using the dimine and / or the dianhydride including the hydrophilic substituent, or the diamine and the dianhydride It can be prepared by polymerizing a comonomer containing a hydroxyl group together. The comonomer including the hydroxy group may be any one selected from the group consisting of dianiline including a hydroxy group, diphenyl urea including a hydroxy group, diamine including a hydroxy group, and a combination thereof.

When the main chain of the polyimide includes the hydrophilic substituent, the hydrophilic substituent may include 0.01 to 0.1 mol%, preferably 0.01 to 0.08 mol%, more preferably 0.02 to 0.08 mol% with respect to the entire polyimide. . When the content of the hydrophilic substituent is less than 0.01 mol%, hydrophilization may be insufficient due to the decrease of the hydrophilic group of the polyimide main chain, and when the content of the hydrophilic substituent exceeds 0.1 mol%, side reaction generation and physical elongation may be deteriorated.

As described above, when the nanofiber is made of a hydrophobic polymer such as polyimide, the nanoweb may be plasma-treated on one or both surfaces to satisfy the saturation moisture arrival time, moisture content, wettability or contact angle by wicking test. Can be. Plasma treatment of the nanoweb may replace a functional group having any hydrophilicity selected from the group consisting of carboxyl groups, hydroxyl groups, amine groups, and combinations thereof on the surface of the nanoweb.

Specifically, the plasma treatment may be performed by using a low temperature plasma or a radio frequency (RF) plasma with a gas capable of imparting a hydrophilic group to one or both surfaces of the nanoweb. 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, and the flow rate of the gas capable of imparting the hydrophilic group may be 10 to 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.

In addition, as described above, when the nanofibers are made of a hydrophobic polymer such as polyimide, an inorganic material on one or both surfaces of the nanoweb to satisfy the saturation moisture arrival time, moisture content, wettability or contact angle by the wicking test. This can be deposited. The inorganic material is 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 ), aluminum oxide ( Al ₂ O ₃ ), single-walled oxide carbon nanobubble, multi-walled carbon nanotube oxide, graphite oxide, graphene oxide and a combination thereof may be any one selected from the group.

The porous support not only has excellent air permeability and water permeability, but also has excellent heat resistance and chemical resistance, and is required for gas or liquid filters, filter for dust masks, venting for automobiles, and venting for mobile phones. , Filter materials such as printer vents, high-end garment materials such as breathable tarps, electrochemical materials such as polymer electrolytes of fuel cells, secondary cells, electrolysis devices or separators of capacitors, dressings for wound healing, artificial blood vessels It can be used as a medical material such as a support, a bandage, a cosmetic mask and the like.

According to another embodiment of the present invention, a method of manufacturing a porous support includes electrospinning an electrospinning solution to produce a nanoweb in which nanofibers are integrated into a nonwoven fabric including a plurality of pores.

For example, when the nanofibers are made of polyimide which is a hydrophobic polymer, the method of preparing the porous support may include adding diamine and dianhydride to a solvent to prepare an electrospinning solution, and electrospinning the prepared electrospinning solution. Preparing a polyamic acid nanoweb in which the nanofibers are integrated in a nonwoven form including a plurality of pores, and imidizing the polyamic acid nanoweb to produce a polyimide nanoweb.

Looking at each step below, the electrospinning solution is a solution containing the monomers for forming the nanofibers, the monomers for forming the nanofibers exhibit excellent chemical resistance, has a hydrophobic property by moisture in a high humidity environment Hydrocarbon type polymer which does not have a possibility of morphological modification can be used preferably.

Specifically, the hydrocarbon-based polymer may be nylon, polyimide, polyaramid, polyetherimide, polyacrylonitrile, polyaniline, polyethylene oxide, polyethylene naphthalate, polybutylene terephthalate, styrene butadiene rubber, polystyrene, polyvinyl chloride, Polyvinyl alcohol, polyvinylidene fluoride, polyvinyl butylene, polyurethane, polybenzoxazole, polybenzimidazole, polyamideimide, polyethylene terephthalate, polyethylene, polypropylene, copolymers thereof, and mixtures thereof One selected from the group consisting of can be used, and among them, it is preferable to use a polyimide which is more excellent in heat resistance, chemical resistance, and shape stability. Hereinafter, the case where a nanofiber consists of polyimide which is a hydrophobic polymer is demonstrated concretely.

The monomer for forming the nanofibers may be used without particular limitation as long as it can form the hydrocarbon-based polymer. For example, a nanoweb containing polyimide is prepared by using a polyamic acid (PAA) as a polyimide precursor that is well soluble in an organic solvent, and then undergoes imidization reaction in a subsequent curing process. It can be prepared through.

The polyamic acid nanoweb may be prepared according to a conventional manufacturing method, specifically, diamine may be prepared by mixing diamine in a solvent, adding dianhydride thereto, and then electrospinning it.

Examples of the dianhydride include pyromellyrtic 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 anhydride (3,4', 3,4 ') A compound selected from the group consisting of -biphenyltetracarboxylic dianhydride (BPDA), and bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride (SiDA) and mixtures thereof can be used. As the diamine, 4,4'-oxydianiline (ODA), 1,3-bis (4-aminophenoxy) benzene (1,3-bis (4-aminophenoxy) benzene , RODA), p-phenylene diamine (p-PDA), o-phenylene diamine (o-phenylene diamine, o-PDA) and mixtures thereof may be used. The polyamic acid Dissolving solvents include m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), acetone, diethyl acetate, A solvent selected from the group consisting of tetrahydrofuran (THF), chloroform, γ-butyrolactone and mixtures thereof may be used.

Monomers for forming the nanofibers are preferably included in 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 spinning may not proceed smoothly, and fiber formation may not be achieved or fibers having a uniform diameter may be produced, whereas the content of the monomers may exceed 20% by weight. In this case, as the discharge pressure increases rapidly, spinning may not be performed or processability may be reduced.

In step 2, the electrospinning solution is spun to prepare a nanoweb precursor, that is, a polyamic acid nanoweb. The spinning is not particularly limited in the present invention, but may be electrospinning, electro-blown spinning, centrifugal spinning, melt blowing, or the like. Emission can be used.

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

1 is a schematic diagram of a nozzle type electrospinning apparatus. Referring to FIG. 1, the electrospinning supplies a predetermined amount of the precursor solution to the nozzle 3 using the metering pump 2 in the solution tank 1 in which the nanofiber precursor solution is stored, and the nozzle ( After discharging the solution of the nanofiber precursor through 3), the coagulated nanofiber precursor was formed simultaneously with scattering, and the coagulated nanofiber precursor was further concentrated in the collector 4 to prepare the precursor nanofiber of the porous support. have.

In this case, the electrospinning may be performed in a state in which the positive charge density around the nozzle is increased and the negative charge density around the collector is increased. Through this, the droplets of the polymer can be spun and scattered, and at the same time, they can repel each other to collect nanofibers. The area around the nozzle or around 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 installing a high voltage generator (not shown) capable of supplying positive charge around the nozzle, and the negative charge density around the collector is a high voltage capable of supplying negative charge around the collector. It can be adjusted by installing a generator (not shown).

The degree of increasing the positive charge density around the nozzle can be controlled by supplying positive charges around the nozzle at +10 to +100 kV, and the degree of increasing the negative charge density around the collector is supplied at 0 to -100 kV around the collector. Can be adjusted. If the positive charge supply is less than + 10kV, the radiation force may be insufficient, if the + 100kV exceeds the electrical insulation may be destroyed, if the negative charge supply is less than 0 the potential difference may be insufficient, if the insulation exceeds -100kV 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 generator 6 and the voltage transfer rod 5 is preferably 850 to 3,500 V / cm. If the strength of the electric field is less than 850 V / cm, it is difficult to manufacture a nanofiber having a uniform thickness because the precursor solution is not continuously discharged, and the nanofibers formed after the spinning cannot be smoothly focused on the collector. Fabrication of the web may be difficult, and nanowebs having a normal shape cannot be obtained because the nanofibers do not settle correctly in the collector 4 when the electric field strength exceeds 3,500 V / cm.

Through the spinning process, a nanofiber precursor having a uniform fiber diameter, preferably an average diameter of 0.01 to 5 μm is prepared, and the nanofiber precursor is arranged in a predetermined direction or randomly to have a nonwoven form.

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

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

Accordingly, the temperature during the curing process is preferably adjusted in consideration of the conversion rate of the nanofiber precursor. Specifically, it is preferable that a curing process at 80 to 650 ° C is performed. When the curing temperature is less than 80 ℃ conversion rate is low, as a result there is a fear that the heat resistance and chemical resistance of the nano-web, and when the curing temperature exceeds 650 ℃ due to decomposition of the nanofibers nano web There is a fear that the physical properties of the.

Meanwhile, as described above, when the nanofiber is made of a hydrophobic polymer such as polyimide, the nanoweb may include a hydrophilic additive to satisfy the saturation moisture arrival time, moisture content, wettability or contact angle by a wicking test. have. That is, the nanofibers themselves may include the hydrophilization additive, the hydrophilic additive may be impregnated in the pores of the nanoweb, the hydrophilic additive is coated on the surface of one or both surfaces of the nanoweb It may be.

Specifically, when the nanofibers include the hydrophilic additive, the hydrophilic additive may be further added to the electrospinning solution and then electrospun. In this case, the hydrophilic additive may include 0.1 to 20 parts by weight, preferably 3 to 20 parts by weight, and more preferably 5 to 20 parts by weight, based on 100 parts by weight of the monomer for preparing the nanofibers. .

When the content of the hydrophilization additive is less than 0.1 parts by weight based on 100 parts by weight of the monomer for producing the nanofibers, the hydrophilic performance is insufficient, the wettability may be lowered, and the performance of the electrochemical device may be lowered. In this case, the instability of the nanofiber jet may be increased in the spinning process and non-uniform fiber focusing may be a problem when applied to the separator of the electrochemical device.

In addition, the spinning of the electrospinning solution can be prepared under normal spinning conditions, but during spinning of the precursor solution containing the hydrophilic additive, the instability of the spinning jet increases, so that the nanofibers are uniformly focused on the collector. It is not possible to manufacture high quality nanowebs. Accordingly, during spinning of the precursor solution including the hydrophilic additive, a cation blower is installed in the surrounding environment to increase the cation density, and the collector surface substrate is exposed to an anion blower to increase the anion density of the collector substrate. Otherwise, stable spinning jets may not be obtained, making it difficult to produce a uniform, high quality support.

When the hydrophilization additive is impregnated in the pores of the nanoweb, or when the hydrophilic additive is coated on the surface of one or both surfaces of the nanoweb, the hydrophilic additive is prepared by adding the hydrophilic additive to a solvent The porous support may be prepared by dipping and impregnating the nanoweb or by coating the hydrophilic additive solution on the surface of the nanoweb.

In the method of impregnating the nanoweb in the hydrophilic additive solution, the nanoweb is immersed in the hydrophilic additive solution for 5 to 30 minutes at room temperature (20 ℃) and then dried at 50 to 100 ℃ hot air oven for more than 3 hours , This may be done by performing the dipping and drying operation 2 to 5 times.

In addition, the method of coating the hydrophilic additive solution on the surface of the nanoweb may use a variety of methods known in the art, such as laminating process, spray process, screen printing process, doctor blade process.

The hydrophilic additive solution is 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 ), Any one inorganic hydrophilic additive selected from the group consisting of aluminum oxide (Al ₂ O ₃ ), single-walled carbon nanobub oxide, multi-walled carbon nanotube oxide, graphite oxide, graphene oxide and combinations thereof Any one of organic solvents selected from the group consisting of polyhydroethyl methacrylate, polyvinylacetate, polyurethane, polydimethylsiloxane, polyimide, polyamide, polyethylene terephthalate, polymethyl methacrylate, epoxy and combinations thereof Hydrating additives include N-methyl-2-pyrrolidine (NMP), dimethylformamide (DMF), dimethyl acetacea It can be prepared by adding and mixing to any one solvent selected from the group consisting of amide (dimethylacetamide, DMA), dimethylsulfoxide (dimethylsulfoxide, DMSO) and combinations thereof.

As described above, when the prepared nanoweb is made of a polyimide which is a hydrophobic polymer, the main chain of the polyimide may have an amine group, a carboxyl group, or a hydride to satisfy the saturation moisture arrival time, moisture content, wettability or contact angle by a wicking test. It may include any one hydrophilic substituent selected from the group consisting of a hydroxyl group and a combination thereof.

That is, in order to produce a nanoweb made of a polyimide containing the hydrophilic substituent in the main chain, the method of preparing the porous support is prepared after the polyimide or the polyamic acid and the polyimide or the polyamic acid in the main chain Substituting hydrophilic substituents, preparing polyimides using dimines and / or dianhydrides containing the hydrophilic substituents, or combining comonomers containing the hydroxy groups in addition to the diamines and dianhydrides It can be prepared by polymerization.

In the method of replacing the hydrophilic substituent on the main chain of the polyimide or the polyamic acid, a carboxyl group and an amine group may be substituted in a part of the main chain by treating with an aqueous alkali solution such as KOH or NaOH.

In addition, the comonomer containing the hydroxy group can be any of those that can be polymerized with the diamine and / or the dianhydride including the hydrophilic substituent, for example, dianiline, hydroxy containing a hydroxy group Any one selected from the group consisting of diphenyl urea containing an oxy group, diamine containing a hydroxy group, and a combination thereof can be used.

As described above, when the nanofiber is made of a hydrophobic polymer such as polyimide, an inorganic material is deposited on one or both surfaces of the nanoweb to satisfy the saturation moisture arrival time, moisture content, wettability or contact angle by the wicking test. Can be.

The deposited inorganic layer is 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 ), Chemical vapor deposition (CVD) of any one precursor selected from the group consisting of aluminum oxide (Al ₂ O ₃ ), single-walled carbon nanobubbles, multi-walled carbon nanotubes, graphite oxide, graphene oxide, and combinations thereof Or physical vapor deposition (PVD) methods including sputtering. Conditions for the deposition may be a 1 minute to 60 minutes treatment in a 50 to 300 ℃ temperature atmosphere after placing a carpet that can give a hydrophilic group on the surface using an RF sputter or a vapor deposition machine.

Reinforcing membrane according to another embodiment of the present invention includes the porous support and the ion exchange polymer filled in the pores of the porous support.

Impregnation is a method of filling the ion exchange polymer into the pores of the porous support. 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 immersing a related monomer or low molecular weight oligomer in the porous support, and then in-situ polymerization in the porous support.

The impregnation temperature and time may be influenced by various factors. For example, it may be influenced by the thickness of the nanoweb, the concentration of the ion exchange polymer, the kind of the solvent, the concentration of the ion exchange polymer to be impregnated into the porous support, and the like. However, the impregnation process may be made at a temperature of less than 100 ℃ at any point of the solvent, and more generally at a temperature of less than 70 ℃ at room temperature (20 ℃). However, the temperature may not be higher than the melting point of the nanofibers.

The ion exchange polymer may be a cation exchange polymer having a cation exchange group such as proton or an anion exchange polymer having an anion exchange group such as hydroxy ion, carbonate or 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, and in general, may be a sulfonic acid group or a carboxyl group. have.

The cation exchange polymer includes the cation exchange group, the fluorine-based polymer containing fluorine in the main chain; Benzimidazole, polyamide, polyamideimide, polyimide, polyacetal, polyethylene, polypropylene, acrylic resin, polyester, polysulfone, polyether, polyetherimide, polyester, polyethersulfone, polyetherimide, poly Hydrocarbon-based polymers such as carbonate, polystyrene, polyphenylene sulfide, polyether ether ketone, polyether ketone, polyaryl ether sulfone, polyphosphazene or polyphenylquinoxaline; Partially fluorinated polymers such as polystyrene-graft-ethylenetetrafluoroethylene copolymer or polystyrene-graft-polytetrafluoroethylene copolymer; Sulfone imides and the like.

More specifically, when the cation exchange polymer is a hydrogen ion cation exchange polymer, the polymers may include a cation exchange group selected from the group consisting of sulfonic acid groups, carboxylic acid groups, phosphoric acid groups, phosphonic acid groups, and derivatives thereof in the side chain. Specific examples thereof include poly (perfluorosulfonic acid) containing a sulfonic acid group, poly (perfluorocarboxylic acid), a copolymer of tetrafluoroethylene containing a sulfonic acid group and fluorovinyl ether, and a defluorinated sulfide polyether. Fluorine-based polymers including ketones or mixtures thereof; Sulfonated polyimide (S-PI), sulfonated polyarylethersulfone (S-PAES), sulfonated polyetheretherketone (SPEEK), sulfonated polybenzimine Sulfonated polybenzimidazole (SPBI), sulfonated polysulfone (S-PSU), sulfonated polystyrene (S-PS), sulfonated polyphosphazene and mixtures thereof Hydrocarbon-based polymers include, but are not limited thereto.

The anion exchange polymer is a polymer capable of transporting anions such as hydroxy ions, carbonates or bicarbonates, and the anion exchange polymer is commercially available in the form of a hydroxide or halide (generally chloride), and the anion exchange polymer Can be used for industrial water purification, metal separation or catalytic processes.

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

The ion exchange polymer may be included in 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 ion conductivity of the reinforcing film may be lowered. If the content of the ion exchange polymer is more than 99% by weight, the mechanical strength and dimensional stability of the reinforcing film may be reduced. .

In addition to filling the pores of the porous support, the ion exchange polymer may form a coating layer on one or both surfaces of the porous support. Preferably, the coating layer of the ion exchange polymer is adjusted to a thickness of 30 μm or less. When the coating layer of the ion exchange polymer is formed to a thickness of more than 30 μm on the surface of the porous support, the mechanical strength of the reinforcing film is increased. It may be lowered, leading to an increase in the overall thickness of the reinforcement film, and thus an increase in resistance loss.

Since the reinforcing film has a 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 improved, the thickness of the entire reinforcement film can be reduced to 80 μm or less. As a result, the ion conduction rate is increased and the resistance loss is reduced while saving material costs.

In addition, since the reinforcing membrane includes a porous support having excellent durability and excellent binding force between the nanofibers and the ion-exchange polymer constituting the porous support, the three-dimensional expansion of the reinforcing film due to moisture can be suppressed, so that the length and thickness expansion rate This is relatively low. Specifically, the reinforcing film exhibits excellent dimensional stability of 5% or less when swollen in water. The dimensional stability is a physical property evaluated according to Equation 4 below from the change in length before and after swelling when the reinforcing film is swelled in water.

[Equation 4]

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

Since the reinforcing membrane has excellent dimensional stability and ion conductivity, it may 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 practice the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

[제조예 1: 다공성 지지체의 제조]Preparation Example 1: Preparation of Porous Support

(실시예 1-1)(Example 1-1)

100 parts by weight of PMDA and ODA and PDA monomer and 5 parts by weight of anatase-type nano TiO ₂ hydrophilic additive were dissolved in a dimethylformamide solution to prepare 5L of a spinning solution having a solid content of 12.5% by weight and 620poise. After transporting the prepared spinning solution to the solution tank, it was supplied to the spinning chamber consisting of 26 nozzles and a high voltage of 49kV through a quantitative gear pump to produce a polyamic acid nanoweb. The solution feed amount was 1.0 ml / min. In addition, by installing a cationic blower and an anion blower in the spinning chamber and the collector substrate, respectively, the radiation environment increased the cation density, and the collector substrate increased the anion density.

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

(실시예 1-2)(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 the hydrophilic additive.

(실시예 1-3)(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 the hydrophilic additive.

(비교예 1-1)(Comparative Example 1-1)

100 parts by weight of PMDA, ODA, and PDA monomer were dissolved in a dimethylformamide solution to prepare 5 L of a spinning solution having a solid content of 12.5% by weight and 620 poise. After transporting the prepared spinning solution to the solution tank, it was supplied to the spinning chamber consisting of 26 nozzles and a high voltage of 49kV through a quantitative gear pump to produce a polyamic acid nanoweb. The solution feed amount was 1.0 ml / min. Subsequently, the polyamic acid nanoweb was thermally cured for 10 minutes in a continuous curing furnace maintained at a temperature of 420 ° C. to prepare a porous support composed of polyimide nanoweb.

[시험예 1: 다공성 지지체의 특성 측정]Test Example 1: Measurement of Characteristics of Porous Support

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

Table 1

	Example 1-1	Example 1-2	Example 1-3	Comparative Example 1-1
Saturation Moisture 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) Saturation Moisture Attainment Time (sec): KS K ISO 9073-6, Textiles-Nonwovens Test Method-Part 6: Absorption Measurement According to the liquid hygroscopic time method, the specimen is completely wetted by dropping water at a height of 25 mm. Measure your time.

2) Moisture content (% by weight): KS K 0221 Textile Moisture Determination Method: According to the oven balance method, after the specimen reached the water equilibrium in the fiber laboratory standard state (KS K 0901) for 24 hours, at 105 to 110 ℃ After drying for 1 hour and 30 minutes, the weight change rate is measured.

3) Wetability (cm): Immersion of specimens in accordance with B (Option B, Measure distance at a given time) of US AATCC Test Method 197-2011, Vertical Wicking of Textiles. Measure the wicking maximum distance 30 minutes later.

4) Contact angle (°): Fill the syringe with distilled water at 30 ° C and 40% RH, drop a 3 mm diameter drop onto the separator, wait for 5 minutes to spread, and wait 5 minutes after separation Measure this contact angle.

Referring to Table 1, it can be seen that the porous membrane prepared in the example is superior in hydrophilicity to the membrane prepared in the comparative example.

[제조예 2 다공성 지지체의 제조]Preparation Example 2 Preparation of Porous Support

(실시예 2-1)(Example 2-1)

PMDA, ODA, and PDA monomer were dissolved in dimethylformamide solution to prepare 5 L of a spinning solution having a solid content of 12.5 wt% and 620 poise. After transporting the prepared spinning solution to the solution tank, it was supplied to the spinning chamber consisting of 26 nozzles and a high voltage of 49kV through a quantitative gear pump to produce a polyamic acid nanoweb. The solution feed amount was 1.0 ml / min.

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

On the other hand, anatase-type nano TiO ₂ as a hydrophilic additive was added to dimethylformamide and stirred to prepare a hydrophilic additive solution. After immersing the prepared nanoweb in the prepared hydrophilic additive solution for 10 minutes at room temperature (20 ℃) and dried at 80 ℃ hot air oven for more than 3 hours, by performing such immersion, drying operation 2 to 5 times The hydrophilization additive was impregnated into the nanoweb.

(실시예 2-2)(Example 2-2)

A porous support was prepared in the same manner as in Example 2-1, except that the hydrophilic additive solution was coated on both surfaces of the nanoweb using a spray and then dried. It was.

(실시예 2-3)(Example 2-3)

Subsequently, the polyamic acid nanoweb was thermally cured for 10 minutes in a continuous curing furnace maintained at a temperature of 420 ° C. to manufacture polyimide nanoweb. Both surfaces of the prepared polyimide nanoweb were prepared using low temperature plasma. Oxygen gas was introduced into the plasma processing chamber at a flow rate of 150 sccm and then plasma treated at 20 W for 5 minutes.

(실시예 2-4)(Example 2-4)

Subsequently, the polyamic acid nanoweb was thermally cured for 6 minutes in a continuous curing furnace maintained at a temperature of 420 ° C. to prepare a polyimide nanoweb. Both surfaces of the prepared polyimide nanoweb were deposited at 150 W using RF sputtering, and the specimen temperature was fixed at 200 ° C., and sputtered for 10 minutes to form a TiO ₂ inorganic layer.

[시험예 2: 다공성 지지체의 특성 측정]Test Example 2: Measurement of Characteristics of Porous Support

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

TABLE 2

	Example 2-1	Example 2-2	Example 2-3	Example 2-4	Comparative Example 1-1
Saturation Moisture 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

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

[제조예 3 다공성 지지체의 제조]Preparation Example 3 Preparation of Porous Support

(실시예 3-1)(Example 3-1)

PMDA, ODA and PDA, and diphenyl containing hydroxy groups Urea The monomer was dissolved in a dimethylformamide solution at a weight ratio of 50: 45: 5 to prepare 5 L of a spinning solution having a solid content of 12.5% by weight and 620 poise.

After transporting the prepared spinning solution to the solution tank, it was supplied to the spinning chamber consisting of 26 nozzles and a high voltage of 49kV through a quantitative gear pump to produce a polyamic acid nanoweb. The solution feed amount was 1.0 ml / min.

(실시예 3-2)(Example 3-2)

PMDA, ODA, and PDA monomer were dissolved in dimethylformamide solution to prepare 5 L of a spinning solution having a solid content of 12.5% by weight and 620 poise. After transporting the prepared spinning solution to the solution tank, it was supplied to the spinning chamber consisting of 26 nozzles and a high voltage of 49kV through a quantitative gear pump to produce a polyamic acid nanoweb. The solution feed amount was 1.0 ml / min.

Spraying 0.1N KOH solution for 1 second using a spray on the surface of the prepared polyimide nanoweb and dried to replace the carboxyl group to 0.02 mol% in the main chain of the polyimide.

(실시예 3-3)(Example 3-3)

Spraying 0.1N NaOH solution for 1 second using a spray on the surface of the prepared polyimide nanoweb and dried to replace the carboxyl group with 0.01 mol% in the main chain of the polyimide.

[시험예 3: 다공성 지지체의 특성 측정]Test Example 3: Measurement of Properties of Porous Support

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

TABLE 3

	Example 3-1	Example 3-2	Example 3-3	Comparative Example 1-1
Saturation Moisture 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

4) Contact angle: Fill the syringe with distilled water at 30 ° C and 40% RH, drop a 3mm diameter droplet onto the separator, wait for 5 minutes for the droplet to spread, and contact angle between the membrane and the droplet after 5 minutes. Measured.

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

[제조예 4: 강화막의 제조]Production Example 4: Production of Reinforcement Film

In a Petri dish, 5% by weight of Nafion solution together with the porous support prepared in Preparation Examples 1 to 3 was added to impregnate 0.06 g of Nafion per unit area (cm ² ) of the web, and using an oven It was dried at 60 ℃ for 4 hours or more to prepare a reinforcing film.

[시험예 4][Test Example 4]

After immersing the reinforcing film prepared in Preparation Example 4 in 1 mol sulfuric acid solution for 3 hours to fully activate the hydrophilic group, and then wipe the surface with ultrapure water to prepare a sample for conductivity measurement, 90% humidification, 4-electrode method through a resistance measuring device The ion conductivity was measured at 25 ° C. and 80 ° C., respectively.

In addition, the reinforcing film prepared in Preparation Example 4 was dried in a 60 ° C. oven for at least 6 hours and then stored twice at 80 ° C. for 2 hours in a single cycle. Tensile strength was measured and whether or not detachment phenomenon occurred.

In addition, to evaluate the shape stability of the reinforcing film prepared in Preparation Example 4, the reinforcing film was dried for 6 hours at a temperature of 50 ℃ in a hot air oven and then immersed in ultrapure water for 24 hours to measure the dimensional change of the reinforcing film.

The measurement results are shown in Table 4 below.

Table 4

	Ionic Conductivity (Scm ^-1 )		Tensile Strength (MPa)		Tally	Dimensional rate of change (%)
	25 ℃	80 ℃	Before evaluation	5 times	Tally	X	Y
Example 1-1	0.07	0.08	47	45	Tally X	One	One
Example 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
Example 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
Comparative Example ¹	0.09	0.10	36	26	Tally	10.0	10.0

1) Comparative Example: A polymer electrolyte membrane prepared by immersing a Dupont Nafion 117 membrane in ultrapure water for 3 hours or more so that sufficient water exists in the membrane.

As shown in Table 4, the reinforcing film of the Example and the reinforcing film of the Comparative Example exhibited the same level of hydrogen ion conductivity at 25 ℃ compared to the fluorine-based strengthening film of the control example known to exhibit excellent hydrogen ion conductivity. However, at 80 ° C. high temperature, the reinforcing film of the Example showed the same level of hydrogen ion conductivity as the fluorine-based reinforcing film of the control example, whereas the reinforcing film of the comparative example showed a significantly lower ion conductivity than the fluorine-reinforcing film of the control example.

In addition, it can be seen that the reinforcing membrane of the embodiment exhibits significantly improved morphological stability compared to the electrolyte membrane of the fluorine-based polymer of the comparative example known to exhibit excellent hydrogen ion conductivity.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Since the porous support of the present invention has a wide surface area and excellent porosity, it can be used for various purposes such as water purification filters, air purification filters, composite materials, battery separators, and the like, and is particularly useful for reinforced composite membranes used in fuel cells for automobiles. Can be applied.

Claims

The nanofibers comprise a nanoweb integrated into a nonwoven form containing a plurality of pores,

A porous support having a saturation moisture arrival time of the nanoweb is 1 second to 600 seconds.
The method of claim 1,

The nanoweb has a moisture content of 3.0% by weight or more.
The method of claim 1,

The nanoweb has a wettability of 2 to 15 cm by wicking test (wicking test).
The method of claim 1,

The nanoweb has a contact angle (90) or less of the porous support.
The method of claim 1,

The nanofiber is a porous support comprising 0.1 to 20 parts by weight of a hydrophilic additive based on 100 parts by weight of the nanofiber polymer.
The method of claim 1,

Porous support is impregnated with a hydrophilic additive in the pores of the nanoweb.
The method of claim 1,

Porous support that is coated with a hydrophilic additive on one or both surfaces of the nanoweb.
The method according to any one of claims 5 to 7,

The hydrophilization additive is 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 ), oxide Aluminum (Al 2 O 3 ), single-walled carbon nanobubble, multi-walled carbon nanotube oxide, graphite oxide, graphene oxide and any one selected from the group consisting of a porous support.
The method according to any one of claims 5 to 7,

The hydrophilic additive is selected from the group consisting of polyhydroethyl methacrylate, polyvinylacetate, polyurethane, polydimethylsiloxane, polyimide, polyamide, polyethylene terephthalate, polymethyl methacrylate, epoxy, and combinations thereof. Which is one porous support.
The method according to any one of claims 5 to 7,

An average particle diameter of the hydrophilic additive is a nano hydrophilic additive of 0.005 to 1㎛.
The method of claim 1,

The nanofibers are polyimide nanofibers.
The method of claim 11,

The backbone of the polyimide is a porous support comprising any substituent selected from the group consisting of amine groups, carboxyl groups, hydroxyl groups and combinations thereof.
The method of claim 12,

The polyimide is a porous support prepared by imidizing a polyamic acid prepared by polymerizing a comonomer including a diamine, a dianhydride, and a hydroxy group.
The method of claim 13,

The comonomer comprising a hydroxy group is any one selected from the group consisting of dianiline containing a hydroxy group, diphenyl urea containing a hydroxy group, diamine containing a hydroxy group and combinations thereof.
The method of claim 1,

The nanoweb is one or both surfaces of the porous support that is plasma-treated.
The method of claim 1,

Inorganic material is deposited on the surface of one or both surfaces of the nanoweb.
The method of claim 16,

The inorganic material is 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 ), aluminum oxide ( Al 2 O 3 ), single-walled oxide carbon nanobubble, multi-walled carbon nanotube oxide, graphite oxide, graphene oxide and any one selected from the group consisting of a porous support.
Adding diamine and dianhydride to a solvent to prepare an electrospinning solution,

Electrospinning the prepared electrospinning solution to prepare a polyamic acid nanoweb in which nanofibers are integrated into a nonwoven fabric including a plurality of pores, and

Imidating the polyamic acid nanoweb to prepare a polyimide nanoweb;

Method for producing a porous support of the polyimide nanoweb saturation moisture arrival time is 1 second to 600 seconds.
The method of claim 18,

Method for producing a porous support that further adds a comonomer containing a hydroxyl group to the electrospinning solution.
The method of claim 18,

The main chain of the nanofibers included in the polyimide nanoweb is a method for producing a porous support is substituted with any one substituent selected from the group consisting of amine groups, carboxyl groups, hydroxyl groups and combinations thereof.
Electrospinning the electrospinning solution to produce a nanoweb in which the nanofibers are integrated into a nonwoven form comprising a plurality of pores,

Saturation moisture arrival time of the nanoweb is 1 second to 600 seconds to produce a porous support.
The method of claim 21,

The method of manufacturing a porous support further comprises adding a hydrophilic additive to the electrospinning solution.
The method of claim 21,

Impregnating a hydrophilic additive in the pores of the nanoweb further comprising the step of producing a porous support.
The method of claim 21,

Method of producing a porous support further comprises the step of coating a hydrophilic additive on the surface of one or both surfaces of the nanoweb.
The method of claim 21,

Plasma treatment of one or both sides of the nanoweb further comprising the method of manufacturing a porous support.
The method of claim 25,

The plasma treatment is a method of producing a porous support that is treated with a gas that can impart a hydrophilic group on one or both sides of the nanoweb using a low-temperature plasma or radio frequency (RF) plasma.
The method of claim 21,

Method for producing a porous support further comprises the step of depositing an inorganic material on one or both surfaces of the nanoweb.
The method of claim 27,

The method of depositing the inorganic material is a method for producing a porous support that is sputtering.
The porous support according to claim 1, and

Ion exchange polymer filling the pores of the porous support

Reinforcing film comprising a.