JP2010199030A - Method of manufacturing ion-conductive polymer membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an ion-conductive polymer membrane which has a superior dimensional stability with respect to water absorption, while maintaining high proton conductivity. <P>SOLUTION: In the method of manufacturing the ion-conductive polymer membrane, a three-dimensional fiber assembly sheet is manufactured by adhering between fibers of a fiber assembly composed of a polymer A having an ion-exchange group in collection during a spinning process, and then a hydrophobic polymer B is filled in the air gap of the three-dimensional fiber assembly sheet. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing an ion conductive polymer membrane suitable for a polymer electrolyte fuel cell.

  The fuel cell is a power generation device with low emissions, high energy efficiency, and low environmental burden, and is therefore attracting attention again in recent years due to the increase in global environmental protection. A fuel cell is a power generation device that is expected in the future as a power generation device for a mobile unit such as a relatively small-scale distributed power generation facility, an automobile, or a ship as compared with a conventional large-scale power generation facility. It is also attracting attention as a power source for small mobile devices and portable devices, and is expected to be installed in mobile phones and personal computers in place of secondary batteries such as nickel metal hydride batteries and lithium ion batteries.

  Among them, a polymer electrolyte fuel cell that is attracting attention is generally composed of basic units called membrane electrode assemblies (MEA), and in MEA, an ion conductive polymer membrane (PEM) is sandwiched between a cathode and an anode, Ions formed at the anode are transported to the cathode and a current is passed through an external circuit connected to the electrode. PEMs must not only have adequate ionic conductivity, but must have the mechanical and chemical strengths required under the operating conditions of the power plant.

  As such a PEM material, a super strong acid group-containing fluorine-based polymer is known. However, since these PEM materials are fluorine-based polymers, they are not only very expensive, but also have a low glass transition temperature. Therefore, when the operating temperature of the apparatus is around 100 ° C., moisture retention is sufficient. Not. For this reason, there is a problem that the high ionic conductivity of the fluorinated polymer cannot be fully utilized, and the ionic conductivity is drastically lowered, making it impossible to function as a battery.

  In order to overcome such drawbacks, various PEMs in which sulfonic acid groups are introduced into non-fluorinated aromatic ring-containing polymers have been studied. In view of heat resistance and chemical stability, aromatic polyarylene ether compounds such as aromatic polyarylene ether ketones and aromatic polyarylene ether sulfones are attracting attention as polymer skeletons. (For example, Non-Patent Document 1), sulfonated polyether ether ketone (for example, Patent Document 1), and the like have been reported.

  However, those having sulfonic acid groups introduced into these polymers have the disadvantage that the dimensional change during swelling increases with an increase in the amount of sulfonic acid groups introduced, and membrane breakage is likely to occur under operating conditions such as fuel cells. . In order to remedy this defect, attempts to suppress dimensional changes by introducing structural units that can form crosslinks between polymer chains (for example, Patent Documents 2 to 4), and blending polymers that do not contain ionic groups (See, for example, Patent Documents 5 and 6). However, it is difficult to sufficiently suppress the dimensional change during swelling by crosslinking alone. In addition, it was difficult to achieve both dimensional stability and proton conductivity in the case of compatibility with the blend, and in the case of phase separation, the film strength was reduced due to delamination.

  Attempts have also been made to control the film morphology on a nanometer scale in order to further improve functions such as mechanical strength of the PEM. For example, a block polymer having a hydrophilic-hydrophobic repeating structure has been reported (Patent Document 7). In block polymers, hydrophilic / hydrophobic phase separation on the nanometer order is formed, and effective ion conduction is carried out at the hydrophilic part and mechanical strength, etc. is carried out at the hydrophobic part, thereby improving performance under low humidity. I am letting.

  Furthermore, the thing using the nanofiber of an ion conductive polymer is reported as the same morphological control on a nanometer scale (nonpatent literature 2). In this report, a nanofiber sheet is produced by electrostatic spinning of an ion conductive polymer, and the sheet is contracted by heating or mechanical compression, and then exposed to an organic solvent vapor to bond the fibers to each other. An ion conductive polymer film is obtained by a method of forming an original fiber structure and filling the voids of the sheet with a photocrosslinkable resin.

  However, such an ion conductive polymer membrane has an average fiber diameter or a variation in the average fiber diameter due to swelling due to vapor of the organic solvent. Therefore, there has been a problem that the resin cannot be uniformly impregnated and the dimensional stability becomes insufficient. Furthermore, since the number of steps increases, it cannot always be said that it is simple.

JP-A-6-93114 JP 2003-217342 A JP 2003-217343 A JP 2003-292609 A Japanese translation of PCT publication No. 2003-502828 JP 2003-109624 A

Journal of membrane science, (Netherlands) 1993, 83, p. 211-220 Macromolecules, (USA) 2008, 14, vol. 4569-4572

  The present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a method for producing an ion conductive polymer membrane that is excellent in dimensional stability against water absorption while maintaining high proton conductivity. There is.

  As a result of diligent research to solve the above problems, the present inventors have obtained a mechanical and chemical structure on a three-dimensional fiber structure sheet made of an ionic group-containing polymer having excellent chemical stability and high proton conductivity. The present inventors have found that the above-mentioned problems can be solved by uniformly filling an ionic group-free hydrophobic polymer having excellent stability, and have completed the present invention.

  That is, the present invention provides a three-dimensional fiber structure sheet by bonding a fiber assembly comprising a polymer A having an ion exchange group between fibers at the time of collection in a spinning process, and then producing the three-dimensional fiber structure sheet. This is a method for producing an ion-conductive polymer membrane, characterized in that a hydrophobic polymer B is filled in the voids.

  The ion conductive polymer membrane obtained by the present invention has a uniform hydrophobic polymer B on a three-dimensional fiber structure sheet composed of a polymer A having an ion exchange group having excellent chemical stability and high ion conductivity. Since the ionic conductivity and water absorption effect of the polymer A are expressed, and the ionic conductivity is high, the polymer B can be reinforced with few voids. As a result, it is possible to provide an ion-conducting polymer membrane possessing a trade-off characteristic of being excellent in dimensional stability and mechanical strength.

  For this reason, it is suitable as an ion conductive polymer membrane for fuel cells and the like. In addition, the ion conductive polymer membrane of the present invention has a feature of low methanol permeability, and is useful as an ion conductive polymer membrane for a direct methanol fuel cell. Further, since the fibers can be bonded at the time of spinning, there is an advantageous effect that the manufacturing method is simple.

It is a schematic diagram of an electrostatic spinning apparatus.

DESCRIPTION OF SYMBOLS 1 Electrostatic spinning apparatus 2 Spinning nozzle 3 Solution tank 4 High voltage power supply 5 Counter electrode (collection board)

  The present invention will be specifically described below.

First, the ion conductive polymer in this invention is demonstrated.
The polymer A having an ion exchange group in the present invention is not particularly limited as long as the ionic group is an atomic group having a negative charge, but preferably has a proton exchange ability.

As such a functional group, a sulfonic acid group, a sulfonimide group, a sulfuric acid group, a phosphonic acid group, a phosphoric acid group, and a carboxylic acid group are preferably used. Here, the sulfonic acid group is —SO ₂ (OH), the sulfonimide group is —SO ₂ NHSO ₂ R (where R means an organic group), and the sulfuric acid group is —OSO ₂ (OH), A phosphonic acid group means —PO (OH) ₂ , a phosphoric acid group means —OPO (OH) ₂ , a carboxylic acid group means —CO (OH), and salts thereof.

  Two or more kinds of these ionic groups can be contained in the polymer solid electrolyte, and the function may be further improved by combining them. The combination of two or more kinds of ionic groups is appropriately determined depending on the structure of the polymer. Among these, from the viewpoint of high proton conductivity, the ionic group preferably has at least a sulfonic acid group, a sulfonimide group, and a sulfuric acid group. Moreover, it is most preferable to have at least a sulfonic acid group from the viewpoint of hydrolysis resistance.

  In the present invention, the polymer A having an ion exchange group is not particularly limited as long as it has an ion exchange group. However, from the viewpoint that a polymer having sufficient mechanical strength and high ionic group density can be easily synthesized, polyphenylene oxide. , Polyarylene ether compounds, polyetherketone, polyetheretherketone, polyethersulfone, polyetherethersulfone, polyphenylene sulfide, polyimide, polyetherimide, polyamideimide, polyamide, polyester, polyimidazole, polyoxazole, polyphenylene, polystyrene , Polyethylene, or a polymer obtained by copolymerizing these skeleton components.

  Among these polymers, it is preferable that the polymer A having an ion exchange group is a polyarylene ether compound containing the constituents represented by the general formulas (1) and (2). This is because such a polymer is easy to obtain ultrafine fibers by the electrospinning method described later. In general, polymers having a hydrophilic group have been considered to be difficult to obtain ultrafine fibers by an electrospinning method. However, the present inventors have found that even a polymer having a hydrophilic group can obtain ultrafine fibers in the case of a polymer having high rigidity.

Here, Ar represents a divalent aromatic group, Y represents a sulfone group or a ketone group, R represents H, a sulfonic acid group, a phosphonic acid group, or a salt thereof.

However, Ar ′ represents a divalent aromatic group.

  Furthermore, it is preferable that the polymer A having an ion exchange group is a polyarylene ether-based compound including the constituent components represented by the general formula (3) and the general formula (4).

X represents H or a monovalent cation species.

The molecular weights of these polymers are not particularly limited as long as they are solid at room temperature, but are preferably 1000 or more and 1 × 10 ⁷ or less from the viewpoint of film strength and solubility in a solvent.

  In the present invention, the polymer A having an ion exchange group preferably has an ion exchange capacity (IEC) of 1.0 to 4.0 meq / g, more preferably 1.0 to 3.0 meq / g. When the ion exchange capacity is less than 1.0 meq / g, proton conductivity tends to be low. On the other hand, when the ion exchange capacity exceeds 4.0 meq / g, the polymer is easily dissolved in water.

  In this invention, when producing the three-dimensional fiber structure sheet | seat which consists of the polymer A which has an ion exchange group, it is preferable to adhere | attach between fibers at the time of collection in a spinning process. According to this method, the fiber contact is fixed to ensure ionic conductivity, and since no adhesive is used, the gap of the three-dimensional fiber structure sheet is kept uniform and the hydrophobic polymer B is filled without gaps. Thus, an ion conductive polymer film having excellent dimensional stability can be obtained.

  Examples of the spinning method for producing the three-dimensional fiber structure include a melt blow method and an electrostatic spinning method used when producing a nonwoven fabric. When the melt blow method is used, it is necessary to melt the polymer to be used by heat. Therefore, it is preferable to use the electrospinning method, which is one of the solution spinning methods, because many polymer types can be used.

Here, the electrospinning method is a method for producing a fiber by applying a high voltage to a polymer solution.

  In the present invention, examples of means for producing a three-dimensional fiber structure at the time of spinning include a method of increasing the amount of residual solvent in the fiber at the time of collection and fusing the polymers together by the binder effect of the solvent. In the above method, it is preferable to optimize the concentration of the polymer solution and the distance from the discharge port to the fiber collecting portion. By shortening the distance from the discharge port to the collection part, the time until the fiber is collected can be shortened, and the amount of residual solvent in the fiber can be increased.

  Further, in fiber formation by the electrospinning method, charge concentration occurs as the solvent evaporates, and the solution flow is stretched due to charge repulsion at this time, resulting in thinning of the fiber and increase in surface area. Thereby, evaporation of a solvent is accelerated | stimulated and fiberization advances. Utilizing this phenomenon, the amount of residual solvent in the fiber can be increased. That is, by increasing the polymer concentration, the amount of solvent in the polymer solution decreases, so the opportunity for charge repulsion decreases and stretching becomes difficult. As a result, evaporation of the solvent is suppressed and the amount of residual solvent in the fiber can be increased.

  The voltage applied to the polymer solution is preferably 3 to 100 kV, more preferably 5 to 70 kV, and still more preferably 5 to 50 kV. Note that the polarity of the applied voltage may be either positive or negative.

  The atmosphere for electrospinning is generally performed in the air, but by performing electrospinning in a gas having a higher discharge starting voltage than air such as carbon dioxide, spinning at a low voltage becomes possible. Also, abnormal discharge such as corona discharge can be prevented.

If water is the poor solvent for the polymer, polymer precipitation may occur. Therefore, it is preferable to reduce moisture in the air and prevent polymer precipitation. The moisture in the air is preferably spun at an absolute humidity of 2 to 13 g / m ³ . More preferably, it is ³ to 11 g / m ³ .

  In order to increase the fiber density, the three-dimensional fiber structure sheet made of the polymer A having an ion exchange group produced by the above method may be contracted by heat treatment. The temperature of heat processing will not be specifically limited if it is below the melting point of the polymer A which has an ion exchange group. Further, as another method for increasing the fiber density of the three-dimensional fiber structure sheet, there is a process of applying pressure mechanically with a press machine or the like.

  In the present invention, the hydrophobicity of the hydrophobic polymer B means that the weight loss when the polymer is immersed in pure water at 25 ° C. for 5 hours is 2% or less.

  In the present invention, the hydrophobic polymer B may be a polymer before filling the three-dimensional fiber structure sheet made of the polymer A having a fibrous ion exchange group, or a precursor of the hydrophobic polymer B. May be a polymer that is reacted after filling a three-dimensional fiber structure sheet made of polymer A having an ion exchange group. Furthermore, these polymers B may have a structure crosslinked after filling.

  The method for filling the hydrophobic polymer B is not particularly limited as long as the structure of the three-dimensional fiber structure sheet made of the polymer A having a fibrous ion exchange group is not destroyed. As a method for filling the hydrophobic polymer B, for example, a method in which the polymer B dissolved in a solvent is filled in a three-dimensional fiber structure sheet and the solvent is dried, or a reaction after filling with a light or heat reactive precursor is performed. The method of making it, etc. are mentioned.

  The hydrophobic polymer B to be filled in the three-dimensional fiber structure sheet made of the polymer A having an ion exchange group after being dissolved in a solvent is not particularly limited as long as it is hydrophobic. For example, mechanical and chemical durability In terms of properties, polysulfone, polyethersulfone, polyphenylene sulfide, polyparaphenylene, polyether ketone, polyester, polyimide, polystyrene, polyester, polyamide, polyamideimide, polyurethane, polyethylene, polypropylene, polymethylpentene, polyvinyl fluoride, polyvinylidene Fluoride, polychlorotrifluoroethylene, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl Vinyl ether copolymer, polytetrafluoroethylene, etc. perfluorocyclobutane-containing copolymer. Further, the hydrophobic polymer B may be a single type, a mixture of two or more types, or a copolymer.

  The solvent for dissolving the hydrophobic polymer B is not particularly limited as long as the three-dimensional fiber structure sheet made of the polymer A having an ion exchange group is not dissolved.

  The hydrophobic polymer B precursor that is polymerized by light or heat is not particularly limited as long as the polymer after polymerization is hydrophobic. From the viewpoint of handling, a hydrophobic polymer B precursor that is liquid itself and does not contain a solvent is preferable.

  Preferred examples of the photopolymerizable monomer or oligomer of the hydrophobic polymer B precursor include a monoacryl monomer or oligomer, a diacryl monomer, or an oligomer that is polymerized and cured by ultraviolet irradiation. The hydrogen at the α-position and / or β-position of the vinyl group may be substituted with a phenyl group, an alkyl group, a halogen group or a cyano group.

  Further, among the photopolymerizable monomers or oligomers of the hydrophobic polymer B precursor, as commercially available products, Kayrad R-551 and Kayalad R-712 (all manufactured by Nippon Kayaku Co., Ltd.), NOA60, NOA61, NOA63, NOA65, NOA68, NOA71, NOA72, NOA73, NOA81, NOA83H, NOA88 (all manufactured by Norland) are exemplified.

  A photopolymerization initiator may be used to rapidly polymerize the monomers or oligomers as described above to obtain a desired polymer. Any photopolymerization initiator suitable for the selected monomers and oligomers can be used. For example, Darocur 1173 (manufactured by Merck), Darocur 1116 (manufactured by Merck), Irgacure 184 (manufactured by Ciba Geigy), Irgacure 651 (manufactured by Ciba Geigy), Irgacure 907 (Ciba Geigy) Product), Kayacure DETX (manufactured by Nippon Kayaku Co., Ltd.), Kayacure EPA (manufactured by Nippon Kayaku Co., Ltd.), and the like.

  The heat-polymerizable resin of the hydrophobic polymer B precursor is not particularly limited as long as it reacts at or below the melting point or decomposition temperature of the polymer A having an ion exchange group and becomes a polymer, but is itself liquid and polymerized and cured by heat. Preferred examples of the material include a monomer or an oligomer containing an epoxy group or a trifluorovinyl ether group.

  The ion conductive polymer membrane of the present invention comprises (a) an aggregate of fibers having an average fiber diameter of 0.01 to 1 μm composed of polymer A having an ion exchange group, and the fibers are bonded during spinning. A composite membrane comprising a three-dimensional fiber structure and (b) a hydrophobic polymer B is preferable.

  When the average fiber diameter of the polymer A having an ion exchange group is smaller than 0.01 μm, it becomes difficult to obtain sufficient proton conductivity. On the other hand, when the average fiber diameter of the polymer A is larger than 1 μm, the dimensional stability tends to deteriorate.

  The composition ratio (A / B; mass ratio) of the polymer A having an ion exchange group and the hydrophobic polymer B is preferably 10/90 to 90/10. When the ratio of the polymer A having an ion exchange group is too small, proton conductivity tends to deteriorate. On the other hand, when the ratio of the polymer A is too large, the reinforcing effect of the hydrophobic polymer B cannot be expected.

  The ion conductive polymer membrane of the present invention can have any film thickness depending on the purpose, but is desirably as thin as possible from the viewpoint of ion conductivity. Specifically, the thickness of the ion conductive polymer membrane is preferably 5 to 250 μm, more preferably 5 to 100 μm. When the thickness of the ion conductive polymer membrane is less than 5 μm, it becomes difficult to handle the ion conductive polymer membrane, and a short circuit or the like tends to occur when a fuel cell is formed. On the other hand, when the thickness of the ion conductive polymer film is thicker than 250 μm, the electric resistance value of the ion conductive polymer film becomes high and the power generation performance of the fuel cell tends to be lowered.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not restrict | limited by the following Example from the first. Further, it is of course possible to carry out the present invention with appropriate modifications within a range that can be adapted to the gist of the present invention, all of which are included in the technical scope of the present invention. Moreover, the measuring method for evaluating the physical property and effect which are used by this invention is as follows.

(1) Reduced viscosity The polymer powder dried under reduced pressure at 80 ° C. overnight was dissolved in N-methylpyrrolidone (NMP) at a concentration of 0.5 g / dl. Next, the viscosity was measured using a Ubbelohde viscometer in a high-temperature bath at 25 ° C., and the reduced viscosity (ηsp / c) was evaluated from the following formula.
ηsp / c = [(t−t ₀ ) / t ₀ ] / c
[T ₀ : dropping time of solvent only (s), t: dropping time of sample solution (s), c: concentration of sample solution (g / dl)]

(2) Average fiber diameter of ultrafine single fiber A platinum-palladium alloy is vapor-deposited on the fiber assembly, photographed with a scanning electron microscope (SEM manufactured by SEM Hitachi, S-800), and displayed on a SEM image of 5000 times or 10,000 times. Twenty fibers were randomly selected from the obtained many fibers, and the fiber diameter was measured. The average value of the measured 20 fiber diameters was calculated and used as the average fiber diameter of the ultrafine fibers.

(3) Ion exchange capacity 50 mg of a polymer or electrolyte membrane dried under reduced pressure at 80 ° C. overnight was weighed and stirred in 60 ml of 0.01 M NaOH aqueous solution for 1 hour. Thereafter, 50 ml of the solution was taken out and titrated with an aqueous 0.02M HCl solution using an automatic titrator (HIRANUMA TITSTATION TS-980). Subsequently, the ion exchange capacity (IEC) was calculated using the following formula.
IEC = (blank average dripping amount (ml) −sample dripping amount (ml))
× 1.2 × 0.02 / sample mass (g)

(4) Ion conductivity On a measurement probe (made of PTFE), a platinum wire (diameter: 0.2 mm) was pressed against the surface of a strip-shaped membrane sample having a width of 1 cm, and constant temperature and humidity at 80 ° C. and 95% relative humidity. Samples were held in the bath. Next, the AC impedance at 10 kHz between the platinum wires was measured using a SOLARTRON 1250 FREQUENCY RESPONSE ANALYSER.
Specifically, the inter-electrode distance is changed from 1 cm to 4 cm at intervals of 1 cm, the AC impedance is measured, and the linear slope Dr [Ω / cm] in which the inter-electrode distance and the resistance measurement value are plotted is expressed by the following equation. The calculation was performed by canceling the contact resistance between the membrane and the platinum wire.
σ [S / cm] = 1 / (film width [cm] × film thickness [cm] × Dr [Ω / cm])

(5) Saturated water absorption A 5 cm square sample was vacuum dried at 80 ° C. overnight, and then the dry mass was measured. Next, hold the dried sample in water at 80 ° C. for 1 day or longer, calculate the mass after saturated water absorption (the mass when the mass change disappears after the start of measurement), and calculate the water absorption rate [%] of the sample from the following formula. did.
Saturated water absorption [%] = [(mass after saturated water absorption / dry mass) -1] × 100

(6) Area change rate After a 5 cm square sample was vacuum-dried overnight at 80 ° C, the area after drying was measured. The dried sample was kept in water at 80 ° C. for 1 day or longer, the area after saturated water absorption (the area when the area change disappeared after the start of measurement) was determined, and the area change rate [%] of the sample was calculated from the following formula. .
Area change rate [%] = [(Area after saturated water absorption / Area after drying) -1] × 100

(Synthesis of polymer A having an ion exchange group)
3,3′-disulfo-4,4′-dichlorodiphenylsulfone disodium salt (abbreviation: S-DCDPS) 15.0 g [0.03026 mol], 2,6-dichlorobenzonitrile (abbreviation: DCBN) 6.64 g [ 0.03851 mol], 12.4 g of 4,4′-biphenol [0.06877 mol] and 10.45 g of potassium carbonate were weighed into a 200 ml four-necked flask and flushed with nitrogen. After adding 113 ml of NMP and stirring at 150 ° C. for 1 hour, the reaction temperature was raised to 195-200 ° C., and the reaction was continued with the aim of sufficiently increasing the viscosity of the system (about 6 hours). Thereafter, the mixture was allowed to cool and precipitated into strands in water. The obtained polymer was washed in water and then dried. The reduced viscosity of the polymer was 1.35 (dl / g), and the IEC was 2.05 (meq / g).

Example 1
N, N-dimethylacetamide was added to polymer A having an ion exchange group to make the solid content concentration 22 mass%. The resin solution was discharged to the fibrous material collecting electrode 5 using the apparatus shown in FIG. An 18 G (inner diameter: 0.9 mm) needle was used for the spinning nozzle 2, the voltage was 30 kV, and the distance from the spinning nozzle 2 to the counter electrode 5 for collecting fibers was 10.5 cm. The absolute humidity in the air was 8.0 g / m3. The average fiber diameter of the obtained ultrafine fiber aggregate was 0.07 μm. In addition, the obtained ultrafine fiber aggregate was bonded between the fibers.

A sheet prepared such that the mass ratio of polymer A / polymer B was 70/30 was immersed in UV curable Norland Optical Adhesive (NOA) 63 under reduced pressure for 1 hour. Next, the sheet surface was wiped with filter paper to remove excess NOA63. Further, ultraviolet light having a wavelength of 365 nm was irradiated on one side of the sheet to solidify the polymer over 1 hour. The obtained electrolyte membrane was immersed in 2M-sulfuric acid aqueous solution for 5 hours. Thereafter, it was washed with pure water to obtain an ion conductive polymer membrane.
The properties of this film are shown in Table 1.

(Example 2)
A sheet prepared by the same method as in Example 1 except that the mass ratio of Polymer A / Polymer B was changed to 60/40 was placed in a UV curable Norland Optical Adhesive (NOA) 63 solution under reduced pressure. Soaked for hours. Next, the sheet surface was wiped with filter paper to remove excess NOA63. Further, ultraviolet light having a wavelength of 365 nm was irradiated on one side of the sheet to solidify the polymer over 1 hour. The obtained electrolyte membrane was immersed in 2M-sulfuric acid aqueous solution for 5 hours. Thereafter, it was washed with pure water to obtain an ion conductive polymer membrane.
The properties of this film are shown in Table 1.

(Comparative Example 1)
N, N-dimethylacetamide was added to the polymer A having an ion exchange group to adjust the solid content concentration to 16% by mass. The resin solution was discharged to the fibrous material collecting electrode 5 using the apparatus shown in FIG. An 18 G (inner diameter: 0.9 mm) needle was used for the spinning nozzle 2, the voltage was 38 kV, and the distance from the spinning nozzle 2 to the counter electrode 5 for collecting fibers was 10.5 cm. The absolute humidity in the air was 8.0 g / m ³ .

  The average fiber diameter of the obtained ultrafine fiber aggregate was 0.05 μm. Further, the obtained ultrafine fiber aggregate was not bonded between the fibers.

A sheet prepared so that the mass ratio of polymer A / polymer B was 70/30 was immersed in UV curable Norland Optical Adhesive (NOA) 63 under reduced pressure for 1 hour. Next, the sheet surface was wiped with filter paper to remove excess NOA63. Further, ultraviolet light having a wavelength of 365 nm was irradiated on one side of the sheet to solidify the polymer over 1 hour. The obtained electrolyte membrane was immersed in 2M-sulfuric acid aqueous solution for 5 hours. Thereafter, it was washed with pure water to obtain an ion conductive polymer membrane.
The properties of this film are shown in Table 1.

(Comparative Example 2)
Polymer A was dissolved in NMP so as to be 10% by mass, then cast on a glass plate and dried at 100 ° C. for 4 hours. The obtained electrolyte membrane was immersed in 2M-sulfuric acid aqueous solution for 5 hours. Thereafter, it was washed with pure water to obtain an ion conductive polymer membrane.
The properties of this film are shown in Table 1.

(Comparative Example 3)
The same evaluation as in Example 1 was performed on a single membrane using Nafion (registered trademark; DuPont) 112. Table 1 shows the characteristics.

  From the above results, it can be seen that the composite membrane obtained in the present invention has excellent proton conductivity and excellent dimensional stability against water absorption despite high water absorption. Further, it was found that when the fibers are bonded, the proton conductivity is higher than that when the fibers are not bonded.

  The ion conductive polymer membrane obtained in the present invention is excellent not only in ion conductivity but also in workability and dimensional stability, and is therefore suitable as an ion conductive polymer membrane for fuel cells, etc. Since methanol permeability is low, it is also useful as an ion conductive polymer membrane for direct methanol fuel cells.

Claims (7)

  A fiber assembly composed of a polymer A having an ion exchange group is bonded between fibers at the time of collection in a spinning process to form a three-dimensional fiber structure sheet, and then the voids in the three-dimensional fiber structure sheet are hydrophobic. A method for producing an ion conductive polymer membrane, wherein the polymer B is filled.   2. The ion conductive polymer membrane according to claim 1, wherein the fibers constituting the fiber assembly composed of the polymer A having an ion exchange group are ultrafine fibers having an average fiber diameter of 0.01 to 1 μm. Production method.   The method for producing an ion conductive polymer membrane according to claim 1 or 2, wherein the ion exchange group of the polymer A is a proton exchange group.   4. The ion-conductive polymer membrane according to claim 3, wherein the proton exchange group includes any one of a sulfonic acid group, a sulfonimide group, a sulfuric acid group, a phosphonic acid group, a phosphoric acid group, and a carboxylic acid group. Production method.   Polymer A having an ion exchange group is polyphenylene oxide, polyether ketone, polyether ether ketone, polyether sulfone, polyether ether sulfone, polyphenylene sulfide, polyimide, polyether imide, polyamide imide, polyamide, polyester, polyimidazole, poly The production of an ion conductive polymer film according to any one of claims 1 to 4, which is a polymer having a structure in which oxazole, polyphenylene, polystyrene, polyethylene, or a skeleton component thereof is copolymerized. Method. The polymer A having an ion exchange group is a polyarylene ether-based compound containing structural components represented by the following general formula (1) and general formula (2). The manufacturing method of the ion conductive polymer film as described in a term.
Here, Ar represents a divalent aromatic group, Y represents a sulfone group or a ketone group, R represents H, a sulfonic acid group, a phosphonic acid group, or a salt thereof.
However, Ar ′ represents a divalent aromatic group. 7. The ion conductive polymer according to claim 6, wherein the polymer A having an ion exchange group is a polyarylene ether compound containing the components represented by the general formula (3) and the general formula (4). A method for producing a membrane.
X represents H or a monovalent cation species.