JP2013062240A - Composite polyelectrolyte membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite polyelectrolyte membrane offering excellent ionic conductivity, heat resistance, and mechanical strength, and prevented from undergoing significant dimensional changes between dry and wet states.SOLUTION: The composite polyelectrolyte membrane comprises a composite layer including an aromatic hydrocarbon material with an ionic group and a fluorine-containing polymeric porous body, and the content of the aromatic hydrocarbon material with an ionic group in the composite layer is in the range of 20 wt.% to 95 wt.%.

Description

  The present invention relates to a composite polymer electrolyte membrane used for an electrochemical device such as a fuel cell.

  BACKGROUND ART A fuel cell is a kind of power generation device that extracts electrical energy by electrochemically oxidizing a fuel such as hydrogen or methanol, and has recently attracted attention as a clean energy supply source. In particular, the polymer electrolyte fuel cell has a low standard operating temperature of around 100 ° C. and a high energy density, so that it is a relatively small-scale distributed power generation facility, a mobile power generator such as an automobile or a ship. As a wide range of applications are expected. 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.

  In the polymer electrolyte fuel cell, for example, a cell is formed by sandwiching a membrane electrode assembly between two separators, and a plurality of cells are stacked. The membrane electrode assembly includes an anode and a cathode having a catalyst layer, and a polymer electrolyte membrane disposed between the anode and the cathode. Fluorine ion conductive polymers such as perfluorocarbon polymers having a sulfonic acid group are applied to the polymer electrolyte membrane, and low cost and low environmental impact are expected in the future popularization of polymer electrolyte fuel cells. From the promising point, hydrocarbon-based ion-conducting polymers such as aromatic polyether ether ketones having aromatic acid groups, aromatic polyether ketones and aromatic polyether sulfones have been actively studied. The polymer electrolyte membrane is required to have high proton conductivity.

  In order to increase the proton conductivity of the polymer electrolyte membrane, it is preferable to make the polymer electrolyte membrane thin or increase the ionic group density. However, when the polymer electrolyte membrane is thinned, the mechanical strength of the membrane decreases, and it becomes difficult to process or handle when manufacturing a membrane electrode assembly.

  In addition, since the polymer electrolyte membrane swells due to water generated by the reaction, water vapor supplied with the fuel gas, and the like, and the polymer electrolyte membrane is constrained by a separator or the like, the dimension increase of the polymer electrolyte membrane is It causes local stress concentration. On the contrary, depending on the operating conditions of the fuel cell, the polymer electrolyte membrane is dried and contracted. The dimensional change of the swelling / drying / shrinking cycle (dry / wet cycle) may damage the polymer electrolyte membrane, resulting in a decrease in power generation performance or failure. Here, the polymer electrolyte membrane having an increased ionic group density tends to increase in dimension in the length direction of the membrane when containing water.

  In particular, automotive fuel cells and household fuel cells are being studied for cost reduction for practical use. In order to simplify the water management system, the relative humidity is 60% or less at a high temperature exceeding 80 ° C. It is desired to operate under low humidification conditions, and high temperature and low humidification power generation performance is required.

  Therefore, from the viewpoint of suppressing the mechanical strength and the step change in the wet and dry cycle, as disclosed in Patent Documents 1 and 2, the electrolyte membrane is reinforced with a porous material made of polyacrylonitrile, polyvinyl alcohol, or a fiber nonwoven fabric, and a composite high Molecular electrolyte membranes have been proposed, and Patent Document 3 discloses a composite membrane using a sulfonated polymer porous material, and Patent Document 4 discloses a polymer electrolyte having a high ionic group density on a fluorine-based porous film. An example of a combination of composite membranes filled with is proposed.

JP 2006-73495 A JP 2008-251314 A JP 2003-203648 A International Publication No. 2010/082623 Pamphlet

  The present inventors have found that there are the following problems.

  First, in the composite polymer electrolyte membranes described in Patent Documents 1 and 2, since the composite material other than the polymer electrolyte is a porous material or a nonwoven fabric made of polyacrylonitrile and polyvinyl alcohol, respectively, the composite polymer electrolyte membrane is Insufficient heat resistance. Moreover, since polyvinyl alcohol is easily deteriorated by acid, it is not suitable for a polymer electrolyte having a high ionic group density.

  Also, from the viewpoint of fuel cell system design, it is preferable that the power generation performance is gradually decreased rather than sudden decrease in power generation performance, and the deterioration pattern of the composite polymer electrolyte membrane is closely related to the deterioration pattern of the fuel cell. However, the composite polymer electrolyte membranes described in Patent Documents 1 and 2 tend to cause a phenomenon that the power generation performance is suddenly lowered in the power generation durability test.

  The cause is that when the pinhole of the composite polymer electrolyte membrane grows and the fuel is not sufficiently shut off, the polymer electrolyte deteriorates due to the reaction between the catalyst and the fuel and the influence of heat, and the pinhole grows further. However, it is conceivable that the air electrode and the fuel electrode are short-circuited. Since the composite materials described in Patent Documents 1 and 2 deteriorate in the same manner as the polymer electrolyte, it is difficult to prevent a sudden decrease in power generation performance.

  On the other hand, the description in Patent Document 3 proposes a technique for preventing an increase in ion conduction resistance and improving durability by using a sulfonated porous polymer as a reinforcing material. In the materials described in the document, for example, fuel cells for automobiles and fuel cells for household use are intended for practical use as fuel cells that operate at a high temperature exceeding 80 ° C. and a low humidity condition of 60% or less relative humidity. The power generation performance was insufficient. In Patent Document 4, a combination example of a composite membrane in which a fluorine-based porous film is filled with a polymer electrolyte having a high ionic group density is exemplified in the specification, but a specific composition of the composite layer is described. However, it is estimated that it is difficult to achieve both the power generation performance and durability of the fuel cell operating under the low humidification condition.

  The present invention employs the following means in order to solve such problems. That is, the composite polymer electrolyte membrane of the present invention includes a composite layer composed of an aromatic hydrocarbon-based material having an ionic group and a fluoropolymer porous material, and has the ionic group of the composite layer. The content of the aromatic hydrocarbon material is 20% by weight or more and 95% by weight or less.

  The composite polymer electrolyte membrane of the invention has excellent proton conductivity, small dimensional change in the wet and dry cycle, and improved mechanical strength, so it has excellent high-temperature and low-humidity power generation performance, excellent power generation durability, and sudden performance It is possible to realize a fuel cell that is unlikely to decrease. In particular, it is optimal for fuel cell applications that operate under high humidification conditions such as automobiles and household fuel cells at temperatures exceeding 80 ° C. and a relative humidity of 60% or less.

  Hereinafter, details of preferred embodiments of the present invention will be described.

  The composite polymer electrolyte membrane of the present invention has a composite layer composed of an aromatic hydrocarbon-based material having an ionic group and a fluoropolymer porous material, but has an ionic group-containing aromatic hydrocarbon-based material Plays a role of imparting high elastic modulus, high strength, high heat resistance, and high gas barrier property of the composite polymer electrolyte membrane, and the fluorine-containing polymer porous body plays a role of high toughness and reduction of dimensional change.

  The content of the aromatic hydrocarbon material having an ionic group in the composite layer composed of the aromatic hydrocarbon material having an ionic group and the fluorine-containing polymer porous material is 20% by weight or more and 95% by weight. It is necessary that: By making the aromatic hydrocarbon-based material having an ionic group of the composite layer 20% by weight or more and 95% by weight or less, for the first time, the roles of the two can be balanced, and the proton conductivity and the wet and dry cycle A dimensional change is small, mechanical strength is improved, and when used as an electrolyte membrane for a fuel cell, a fuel cell excellent in power generation performance and excellent in durability can be realized. The content of the aromatic hydrocarbon material having an ionic group is preferably 30% by weight or more, more preferably 75% by weight or less, and more preferably 60% by weight or less.

  In addition, perfluorocarbons in which the fluorinated polymer porous material contains ionic groups are used for fuel cells that operate at a high temperature exceeding 80 ° C. and a low humidity condition of 60% or less relative humidity, such as fuel cells for automobiles and households. From the viewpoint of proton conductivity, it is preferable to be made of a polymer material.

  In addition, as a membrane configuration of the composite polymer electrolyte membrane of the present invention, an aromatic compound having an ionic group on the outside of a composite layer composed of an aromatic hydrocarbon material having an ionic group and a fluoropolymer porous material. It is also preferable to have a layer made of a hydrocarbon-based material or a layer made of a perfluorocarbon-based polymer material containing an ionic group, reducing the interfacial resistance between the electrode catalyst layer and the composite polymer electrolyte membrane, and improving power generation performance Tend to.

  First, an aromatic hydrocarbon material having an ionic group will be described. Examples of the aromatic hydrocarbon material having an ionic group of the present invention include ionic group-containing polyphenylene oxide, ionic group-containing polyether ketone, ionic group-containing polyether ether ketone, ionic group-containing polyether sulfone, ion Ionic group-containing polyether ether sulfone, ionic group-containing polyether phosphine oxide, ionic group-containing polyether ether phosphine oxide, ionic group-containing polyphenylene sulfide, ionic group-containing polyamide, ionic group-containing polyimide, ionic group-containing Examples include polyetherimide, ionic group-containing polyimidazole, ionic group-containing polyoxazole, and ionic group-containing polyphenylene. These may be used alone or in combination. Moreover, a random copolymer may be sufficient and the block copolymer which controlled each unit length of the unit which has an ionic group, and the unit which does not have may be sufficient. A block copolymer is preferable from the viewpoint of ion conductivity. Here, the ionic group is not particularly limited as long as it is a negatively charged atomic group, but is preferably one having 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. Such an ionic group includes a case where it is a salt. Examples of the cation forming the salt include an arbitrary metal cation, NR ₄ ⁺ (R is an arbitrary organic group), and the like. In the case of a metal cation, the valence and the like are not particularly limited and can be used.

  Specific examples of preferred metal ions include Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ti, V, Mn, Al, Fe, Co, Ni, Cu, Zn, Zr, Mo, W, Pt, Rh, Ru, Ir, Pd, etc. are mentioned. Among these, Li, Na, K, Ca, Sr, and Ba are more preferable, and among them, Na and K that are inexpensive and can be easily proton-substituted without adversely affecting the solubility are more preferably used. In addition to the metal salt, the ionic group may be substituted with an ester or the like.

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

  In recent years, simplification of the water management system is considered important for full-scale spread of fuel cells for automobiles and household fuel cells, and power generation conditions are high temperatures exceeding 80 ° C. and low humidification conditions with a relative humidity of 60% or less. There is a case. Therefore, in order to exhibit sufficient power generation performance at such high temperature and low humidity, the ionic group density of the aromatic hydrocarbon-based material having an ionic group is preferably 1.5 mmol / g or more, and 2.0 mmol / G or more is more preferable.

  As an aromatic hydrocarbon material having a particularly preferable ionic group, from the viewpoint of hot water resistance and proton conductivity assuming a wet state at a high temperature exceeding 80 ° C., ionic group-containing polyether ketone, ionic group-containing Examples include polyether ether ketone, ionic group-containing polyether sulfone, and ionic group-containing polyphenylene sulfide.

  The solvent used when the aromatic hydrocarbon material having an ionic group is formed into a solution is also not particularly limited, and can be selected depending on the aromatic hydrocarbon material having the ionic group. For example, aprotic such as N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphontriamide, etc. Polar solvents, ester solvents such as γ-butyrolactone and butyl acetate, carbonate solvents such as ethylene carbonate and propylene carbonate, alkylene such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether and propylene glycol monoethyl ether Glycol monoalkyl ether is suitably used, and may be used alone or as a mixture of two or more.

  In addition, for adjusting the viscosity of aromatic hydrocarbon materials having ionic groups, alcohol solvents such as methanol and isopropanol, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl lactate, hexane , Hydrocarbon solvents such as cyclohexane, aromatic hydrocarbon solvents such as benzene, toluene, xylene, halogenated hydrocarbons such as chloroform, dichloromethane, 1,2-dichloroethane, dichloromethane, perchloroethylene, chlorobenzene, dichlorobenzene Used in combination with solvents, ether solvents such as diethyl ether, tetrahydrofuran, 1,4-dioxane, nitrile solvents such as acetonitrile, nitrated hydrocarbon solvents such as nitromethane and nitroethane, and various low-boiling solvents such as water Kill.

  In addition, when the aromatic hydrocarbon material having an ionic group is hardly soluble in a solvent, a solubility-imparting group can be introduced. The ionic group-containing polyetherketone will be described as an example. A method in which the ketone moiety is substituted with an acetal or ketal moiety to form a solubility-imparting group, and the ketone moiety is a heteroatom analog of the acetal or ketal moiety, such as thioacetal or thioketal. And a method for forming a solubility-imparting group. The solubility-imparting group is hydrolyzed and returned to a ketone by acid treatment or heat treatment described later to obtain an ionic group-containing polyether ketone.

  Next, the fluorine-containing polymer porous body will be described.

  The porous body in the present invention is not particularly limited as long as it has a shape that can be combined with an aromatic hydrocarbon-based material having an ionic group. Examples of such a shape include a film shape, a fibril shape, a woven fabric shape, a nonwoven fabric shape, a sponge shape, a granular shape, and a whisker shape.

  The porosity and thickness of the fluoropolymer porous material are not particularly limited, but are preferable from the viewpoint of the balance between proton conductivity and strength of the composite polymer electrolyte membrane in which a porosity of 30 to 95% is obtained. Although it is determined depending on the use of the composite polymer electrolyte membrane, 5 to 100 μm is a practically adopted film thickness.

  The fluorine-containing polymer material forming the fluorine-containing polymer porous body is not particularly limited as long as there is a site where hydrocarbon H is replaced by F, but a polymer in which 50% or more of H is replaced by F is preferable. For example, homopolymers or copolymers of perfluoroolefins such as tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, and perfluoroalkoxy vinyl ether are exemplified.

  Specific examples thereof include polytetrafluoroethylene (PTFE), polytetrafluoroethylene-hexafluoropropylene (FEP), polytetrafluoroethylene-perfluoropropyl vinyl ether (PFA), polychlorotrifluoroethylene, polytetrafluoroethylene-perfluoro. -2,2-dimethyl-1,3-dioxole, polyperfluorobutenyl vinyl ether and the like.

  In addition, fluorine-containing polymer materials into which ionic groups are introduced can be preferably used. Examples of the method for imparting ion conductivity to the fluorine-containing polymer material include a method of treating with sulfuric anhydride, fuming sulfuric acid, fuming sulfuric acid / triethyl phosphate complex, chlorosulfuric acid, sulfuric acid and the like. You may heat in order to provide ionic conductivity even in a fluorine-containing polymer material. For introducing the ionic group, the ionic group may be formed into a porous body after introducing the ionic group into the fluorine-containing polymer material, or the ionic group may be introduced by the above method after forming the fluorine-containing polymer porous body. Good.

  For example, in the case where the fluoropolymer porous material is a porous film made of a perfluorocarbon polymer material containing an ionic group, the latter is more advantageous in terms of cost since a general-purpose product can be used. In the case of a nonwoven fabric having an average fiber diameter of 10 μm or less made of a perfluorocarbon-based polymer material to be contained, both can be selected, and the porosity can be easily controlled by controlling the fiber diameter and the like, which is preferable.

  When a perfluorocarbon-based polymer material containing an ionic group is used as a nonwoven fabric, it is preferable to mainly use fibers having a diameter of 10 μm or less. The term “subject” as used herein means that it accounts for 50% or more of the fibers in the observation field when observed with an electron microscope or the like. The composite polymer electrolyte membrane can be made thin by mainly using fibers of 10 μm or less, which is preferable from the viewpoint of proton conductivity.

  In addition, in the case of a nonwoven fabric composed only of fibers having a fiber diameter of 10 μm or more, in order to reduce the thickness of the composite polymer electrolyte membrane, the overlap of fibers is reduced, that is, the amount of fibers per unit area is designed to be low. Inevitably, the distance between the fibers increases, the maximum pore diameter increases, and a portion that is not locally combined may occur in the film thickness direction. Depending on the thickness of the composite polymer electrolyte membrane, the portion may trigger deterioration of the composite polymer electrolyte membrane. For the purpose of preventing this phenomenon, fibers mainly having an average diameter of 10 μm or less are mainly used. It is preferable to do. In particular, a nonwoven fabric mainly composed of fibers of 10 μm or less can suppress a decrease in proton conductivity due to an increase in the thickness of the composite polymer electrolyte membrane, and can reduce a portion that is not composited in the film thickness direction. Moreover, it is more preferable that the fiber of 5 micrometers or less is included from a viewpoint of uniform proton conductivity, and a fiber of 1 micrometer or less is still more preferable.

  For example, when producing a non-woven fabric mainly composed of a perfluorocarbon polymer material containing an ionic group of 5 μm or less, a perfluorocarbon system containing an ionic group obtained by electrospinning from the viewpoint of productivity. Examples thereof include a method of forming a nonwoven fabric in which fibers made of a polymer material are directly captured and accumulated on a target. Electrospinning is a method in which fibers are spun electrically by applying a high voltage to a spinning dope.

  Solvents used in the electrospinning of perfluorocarbon polymer materials containing ionic groups are N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide in terms of solubility and handleability. Organic polar solvents such as tetramethylurea, dimethylimidazolidinone, dimethyl sulfoxide, hexamethylphosphonamide, water, alcohols, methyl cellosolves, tetrahydrofuran, toluene and the like. Further, for the purpose of imparting stretchability of the spinning dope, addition of a polyhydric alcohol such as ethylene glycol or glycerin is also preferable. The electrospinning process using the above spinning solution is not particularly limited, and generally known methods and equipment can be used. Manufacturing a non-woven fabric mainly composed of fibers having a diameter of 5 μm or less using a normal non-woven fabric facility is severe in terms of conditions and has many restrictions such as the viscosity of the raw material and stretchability. On the other hand, since the electrospinning method is a spinning method using a spinning raw solution, volume shrinkage occurs during the drying process, and since the spinning raw solution has a low viscosity, molding with an ultrafine nozzle is possible. It is easy to obtain continuous fibers of 5 μm or less.

  In the process of making the fiber made of the perfluorocarbon polymer material containing the ionic group into a non-woven fabric, in the electrospinning process, solidification from the spinning stock solution and spinning by stretching occur simultaneously or sequentially. Therefore, it can be obtained as a nonwoven fabric in which the fibers are bonded by directly capturing the spun fibers on the target. In addition to electrospinning, it is also possible to use a method in which a fluorine-containing polymer material is locally heated with a laser and the fibers are drawn and supplemented by a jet stream or suction to form a nonwoven fabric.

  Alternatively, the obtained fiber may be made into a short fiber to form a fleece, which may be made into a non-woven fabric by a normal dry method or a wet method in which it is dispersed in water to make a non-woven fabric such as a paper making process. In that case, as a method of bonding the fleece, a thermal bond method, a chemical bond method, a needle punch method, a hydroentanglement method, or the like can be used.

  Moreover, as a perfluorocarbon polymer material containing an ionic group, commercially available Nafion (registered trademark: manufactured by Dupont, USA), Aciplex (registered trademark: manufactured by Asahi Kasei Kogyo Co., Ltd.), Flemion (registered trademark: manufactured by Asahi Glass Co., Ltd.), etc. May be used to process into a porous body or a non-woven fabric.

In addition, fluoropolymers that are soluble in specific organic solvents such as polyvinylidene fluoride (PVDF) and copolymers of biridene fluoride and propylene hexafluoride can be electrospun or wet coagulated to produce nonwoven fabrics, microporous membranes, etc. The porous polymer porous body is insoluble in a solvent by contacting with a gas containing fluorine (F ₂ ) and substituting at least part of the hydrogen in the polymer with fluorine. It can be a body.

For example, a step of dissolving PVDF in an organic solvent such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, a step of electrospinning the PVDF solution, and capturing the electrospun fiber. By collecting the PVDF nonwoven fabric and bringing the PVDF nonwoven fabric into contact with the gas containing F ₂ in this order, at least a part of the hydrogen in PVDF is replaced with fluorine, that is, PTFE (polytetrafluoroethylene). Can be obtained.

  Nonwoven fabric containing PTFE has improved resistance to organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, and a solution of the aromatic hydrocarbon material having the ionic group. Thus, it can be suitably used in the case of forming a composite film with a fluoropolymer porous material.

The PVDF solution can be electrospun to form a nonwoven fabric, which enables the formation of a PVDF nonwoven fabric made of nanofibers having an average fiber diameter of 10 μm or less, more preferably 1 μm or less. Spinning time, number of nozzles for electrospinning, collection line Porosity and thickness can be controlled by controlling the speed, and a continuous nonwoven fabric can be produced. Since this PVDF nonwoven fabric is used as a precursor and a gas containing F ₂ is brought into contact with it, it is possible to produce a nonwoven fabric containing PTFE made of nanofibers having a controlled porosity and thickness of 10 μm or less, more preferably 1 μm or less. In addition, a PTFE nanofiber nonwoven fabric having an average fiber diameter of 10 μm or less, more preferably 1 μm or less, which has been difficult to produce in the past, can be obtained, and is a particularly preferable material for the fluoropolymer porous material of the present invention. .

  The PTFE nanofiber nonwoven fabric obtained by the above method can be used for various filters, secondary battery separators, regenerative medical applications, cell growth scaffolds, and the like, in addition to the uses of the present invention. As a method for combining these fluoropolymer porous materials and aromatic hydrocarbon materials having ionic groups, a solution or dispersion of an aromatic hydrocarbon material having ionic groups can be used. Casting method in which molecular material is impregnated and then dried, method of forming aromatic hydrocarbon material having ionic group and fluoropolymer porous body by heat melting, specifically flat plate press, vacuum press For example, a continuous method such as a batch method such as a continuous roll press method, an aromatic hydrocarbon-based material having an ionic group, and a fluorine-containing polymer porous material are mixed, followed by extrusion film formation.

  Specifically, when the fluorine-containing polymer porous body is composited as a filler and fine particles, the filler and the fine particles may be mixed with a solution of an electrolyte membrane material having an ionic group to produce the solution by film formation. Then, after being melt-kneaded by an extruder or the like and pelletized, a composite polymer electrolyte membrane may be produced by melt film formation.

  Further, when the fluoropolymer porous material is a nonwoven fabric, papermaking, or porous film, a solution of an aromatic hydrocarbon material having an ionic group is impregnated in the voids of the fluoropolymer porous material and a solvent is added. The composite polymer electrolyte membrane may be produced by drying.

  In that case, (1) a method of controlling the film thickness by removing a solution of an aromatic hydrocarbon-based material having excess ionic groups while pulling up, or (2) an ionic group on the fluoropolymer porous body (3) A fluorine-containing polymer porous material is pasted on another substrate on which a solution of an aromatic hydrocarbon-based material having an ionic group is cast-coated. Examples thereof include a method of impregnating an aromatic hydrocarbon material having a combined ionic group. Also, in the methods (1) and (2), the method of drying the solvent in the aromatic hydrocarbon-based material having an ionic group by being attached to another base material is a method for reducing the wrinkles and thickness of the composite polymer electrolyte membrane. Unevenness can be reduced, which is preferable in terms of film quality.

  Generally, fluorine-containing polymer materials and aromatic hydrocarbon-based materials have low affinity due to the difference in surface energy, and aromatic hydrocarbon-based materials having ionic groups in the voids of fluorine-containing polymer porous materials are filled well. In such a case, the impregnation property can be improved by introducing the above-mentioned ionic group into the fluoropolymer porous material, or performing corona treatment, plasma treatment, hydrophilic coating treatment, etc. . In particular, porous films made of perfluorocarbon-based polymer materials containing ionic groups and nonwoven fabrics made of perfluorocarbon-based polymer materials containing ionic groups are compatible with aromatic hydrocarbon-based materials having ionic groups. This is preferable. Further, from the viewpoint of film formation such as impregnation property at the time of compounding and stability of quality, it is particularly preferable to use a nonwoven fabric made of a perfluorocarbon polymer material containing an ionic group or a nonwoven fabric containing PTFE.

  As another base material used for the composite polymer electrolyte membrane, generally known materials can be used, but endless belts and drums made of metals such as stainless steel, films made of polymers such as polyethylene terephthalate, polyimide, polyphenylene sulfide, and polysulfone. , Glass, release paper and the like. For metal, etc., the surface is mirror-finished, for polymer films, etc., the coated surface is corona-treated, peeled off, and when continuously coated in roll form, the back of the coated surface is peeled off and wound. It is also possible to prevent the electrolyte membrane and the back side of the coated base material from adhering after removal. In the case of a film substrate, the thickness is not particularly limited, but 30 μm to 200 μm is preferable from the viewpoint of handling.

  Cast coating methods include knife coating, direct roll coating, gravure coating, spray coating, brush coating, dip coating, die coating, vacuum die coating, curtain coating, flow coating, spin coating, reverse coating, and screen printing. Applicable. Improving the impregnation property by reducing pressure and pressure during the impregnation, heating the polymer electrolyte solution, heating the base material and the impregnation atmosphere, etc. is also effective for improving proton conductivity and productivity. .

  There is no restriction | limiting in particular as a film thickness of the composite polymer electrolyte membrane obtained by this invention, Usually, the thing of 3-500 micrometers is used suitably. A thickness of more than 3 μm is preferable to obtain a membrane strength that can withstand practical use, and a thickness of less than 500 μm is preferable for reducing membrane resistance, that is, improving power generation performance. A more preferable range of the film thickness is 5 to 200 μm, and a more preferable range is 10 to 100 μm. This film thickness can be controlled by various methods depending on the coating method. For example, when coating with a comma coater or direct coater, it can be controlled by the solution concentration or the coating thickness on the substrate, and by slit die coating, it is controlled by the discharge pressure, the clearance of the die, the gap between the die and the base material, etc. be able to.

  In addition, the composite polymer electrolyte membrane of the present invention preferably has a step of proton exchange of the metal salt by bringing it into contact with an acidic aqueous solution when an ionic group such as a sulfonic acid group is used in the state of the metal salt. . Further, by bringing the composite polymer electrolyte membrane into contact with water or an acidic aqueous solution, water-soluble impurities, residual monomers, solvents, residual salts, etc. remaining in the membrane can be removed. In the case of an aromatic hydrocarbon material having an ionic group containing a solubility-imparting group, it can be removed in this step. Water and acidic aqueous solution may be heated to promote the reaction.

  The acidic aqueous solution is not particularly limited, such as sulfuric acid, hydrochloric acid, nitric acid, and acetic acid, and the temperature, concentration, and the like can be appropriately selected experimentally. From the viewpoint of productivity, it is preferable to use a 30% by weight or less sulfuric acid aqueous solution of 80 ° C. or less.

  When the composite polymer electrolyte membrane is thin, the mechanical strength during liquid swelling decreases, the membrane tends to break during manufacturing, and wrinkles occur during drying after contact with water and / or acidic solution. And surface defects are likely to occur. For example, when producing a composite polymer electrolyte membrane having a thickness of 30 μm or less at the time of drying, it is preferable to make contact with water and / or an acidic solution without peeling off the membrane from the substrate. It is more preferable if it is 20 μm or less.

  In addition, the composite polymer electrolyte membrane of the present invention has improved mechanical strength and improved thermal stability of ionic groups, improved water resistance, improved solvent resistance, improved radical resistance, and coating properties of the coating liquid. Crystallization nucleating agents, plasticizers, stabilizers, mold release agents, antioxidants, radical scavengers, inorganic fine particles used in crosslinking agents and ordinary polymer compounds for purposes such as improving storage stability Additives such as fillers or fine particles of polyetherketone and polyphenylene sulfide can be added within the range not contrary to the object of the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these. In addition, the measurement conditions of each physical property are as follows.

A. Ionic acid group density The following procedure is repeated 5 times, and the average value of the three points excluding the maximum and minimum values is defined as the ionic acid group density (mmol / g). The unit of concentration is% by weight, and the unit of weight is g.
(1) The produced electrolyte membrane was cut into 5 cm × 5 cm, dried under reduced pressure at 80 ° C. for 12 hours or more with a vacuum dryer, and the weight (Wm) was measured accurately (four digits after the decimal point).
(2) About 30 ml of about 0.2 wt% KCl aqueous solution was prepared in a sample bottle with a lid, and the weight (Wk) and K ion concentration (C ₁ ) of the KCl aqueous solution were measured. The K ion concentration was measured with a capillary electrophoresis apparatus “CAPI-3300” manufactured by Otsuka Electronics. The measurement conditions are as follows.

Measurement method: Drop method (25mm)
Electrophoresis: Otsuka Electronics Cation Analysis Electrophoresis 5 (α-CFI105)
Measurement voltage: 20kV
(3) The electrolyte membrane was immersed in an aqueous KCl solution having a known weight and K ion concentration for 2 hours.
(4) The K ion concentration (C ₂ ) of the aqueous KCl solution was measured again with a capillary electrophoresis apparatus. From the measured value, the sulfonic acid group density was calculated according to the following formula.
Sulfonic acid group density (mmol / g) = [{Wk × (C ₁ -C ₂ ) × 1000} / 39] / Wm
B. Measurement method of fiber diameter The fluoropolymer porous material (nonwoven fabric) was observed with an optical microscope or a scanning electron microscope (SEM), and the diameter of an arbitrary fiber on the screen was shown as an average value measured at 20 points. Further, when the fiber diameter was difficult to measure and the composite polymer electrolyte membrane were observed by the following method.

  A composite polymer electrolyte membrane dried under reduced pressure at 60 ° C. for 24 hours is cut out with a cutter, embedded with an electron microscope epoxy resin (Quetol 812 manufactured by Nissin EM), and the epoxy resin is placed in an oven at 60 ° C. for 48 hours. After curing, an ultrathin section having a thickness of about 100 nm was prepared with an ultramicrotome (Ultracut S manufactured by Leica).

  The prepared ultrathin section was mounted on a 100-mesh Cu grid manufactured by Oken Shoji Co., Ltd., and TEM observation was performed at 100 kV acceleration voltage using a Hitachi transmission electron microscope H-7100FA, and the fiber diameter was measured.

C. Film thickness It measured using Mitutoyo ID-C112 type | mold set to Mitutoyo granite comparator stand BSG-20.

D. Dimensional change rate The electrolyte membrane was cut into a strip of 6 cm × 1 cm, and a marked line was written about 5 mm from both ends on the long side (distance between marked lines was 5 cm). The sample was allowed to stand for 2 hours in a constant temperature bath at a temperature of 23 ° C. and a humidity of 45%, and was quickly sandwiched between two slide glasses, and the distance between marked lines (L ₁ ) was measured with a caliper. Further, after immersing the sample in hot water at 80 ° C. for 2 hours, the sample was quickly sandwiched between _two glass slides, the distance between the marked lines (L ₂ ) was measured with calipers, and the dimensional change rate was calculated according to the following formula.

Dimensional change rate (%) = (L ₂ −L ₁ ) / L ₁ × 100
E. Tensile strength of composite polymer electrolyte membrane when wet
Based on JIS K7127, the sample piece is 1/2 size of dumbbell No. 2 (sample width: 3.0mm, sample length: 16.5mm, 40mm between grips), and the equipment is auto made by Shimadzu with constant temperature and humidity chamber The test was performed at a speed of 200 mm / min using Graph AG-IS 100N. The measurement atmosphere was 80 ° C. and a relative humidity of 94%.

F. Electricity generation evaluation of membrane electrode assembly (MEA) using composite polymer electrolyte membrane (1) Measurement of hydrogen permeation current Commercial electrode, gas diffusion electrode for fuel cell “ELAT (registered trademark) LT120ENSI” 5 g / Prepare a pair of m ² Pt cut to 5 cm square, overlap each other so as to sandwich the composite polymer electrolyte membrane as a fuel electrode and an oxidation electrode, and perform a heat press at 150 ° C. and 5 MPa for 3 minutes, An evaluation MEA was obtained.

Set this MEA in JARI standard cell “Ex-1” (electrode area 25 cm ² ) manufactured by Eiwa Co., Ltd., cell temperature: 80 ° C., supply hydrogen as fuel gas to one electrode and supply nitrogen gas to the other electrode The test was conducted under humidifying conditions: hydrogen gas 90% RH and nitrogen gas 90% RH. The voltage was kept at OCV until it became 0.2 V or less, and the voltage was swept from 0.2 to 0.7 V at 1 mV / sec to examine the change in the current value. In this example, measurement was performed before and after the following start / stop test, and the value at 0.7 V was examined. When the membrane breaks, the amount of hydrogen permeation increases and the permeation current increases. In addition, this evaluation was carried out using a Solartron electrochemical measurement system (Solartron 1480 Electrochemical Interface and Solartron 1255B Frequency Response Analyzer).

(2) Durability test Using the above cell, cell temperature: 80 ° C., fuel gas: hydrogen, oxidizing gas: air, gas utilization rate: hydrogen 70% / oxygen 40%, humidification condition: hydrogen gas 60% RH, air : The test was performed under the condition of 50% RH. The conditions are: hold for 1 minute at OCV, generate electricity for 2 minutes at a current density of 1 A / cm ² , finally stop supplying hydrogen gas and air for 2 minutes, and repeat this as one cycle A sex test was performed. The hydrogen permeation current was measured before and after 3000 cycles and the difference was examined. In addition, the load fluctuation in this test was performed using an electronic load device “PLZ664WA” manufactured by Kikusui Electronics Corporation.

(3) Evaluation of power generation under low humidification The above fuel cell has a cell temperature of 80 ° C., fuel gas: hydrogen, oxidizing gas: air, gas utilization rate: hydrogen 70% / oxygen 40%, humidification condition; anode side 30% RH / Current-voltage (IV) was measured at a cathode of 30% RH and a back pressure of 0.1 MPa (both electrodes), and the voltage at 1 A / cm 2 was read.
G. Content of aromatic hydrocarbon material having ionic group in composite layer composed of aromatic hydrocarbon material having ionic group and fluoropolymer porous material Optical microscope or scanning electron microscope (SEM) The thickness of the composite layer (composite layer) composed of an aromatic hydrocarbon material having an ionic group and a fluorine-containing polymer porous material is observed as T ₁ , and the cross section of the composite polymer electrolyte membrane is observed at If there is another layer on the outside, the thickness is T ₂ , T ₃ , and the specific gravity of the polymer forming each layer is D ₁ , D ₂ , the area of the polymer forming the fluoropolymer porous body When the weight per area is W ₁ , the weight per area of the composite polymer electrolyte membrane is W ₂ , and the weight W ₃ per area of the aromatic hydrocarbon material having an ionic group in the composite layer, the composite layer Aromatic charcoal with ionic groups in it The content Y (wt%) of the hydride-based material was determined by the following formula.
W3 = {W2- (T1 * D1)-(T2 * D2) -W1} (Formula 1)
Y = W3 / (W3 + W1) × 100 (Formula 2)
[Synthesis Example 1; monomer having a solubility-imparting group]
Synthesis of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane (G1) Montmorillonite clay K10 (150 g), 99 g of dihydroxybenzophenone were distilled in 242 mL of ethylene glycol / 99 mL of trimethyl orthoformate to produce by-products. The reaction was carried out at 110 ° C. After 18 hours, 66 g of trimethyl orthoformate was added and reacted for 48 hours of synthesis. To the reaction solution was added 300 mL of ethyl acetate, and after filtration, extraction was performed 4 times with a 2% aqueous sodium hydrogen carbonate solution. Further, after concentration, the desired 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane was obtained by recrystallization from dichloroethane.

[Synthesis Example 2: Monomer having ionic group]
Synthesis of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone (G2) 109.1 g of 4,4′-difluorobenzophenone (Aldrich reagent) and 150 mL of fuming sulfuric acid (50% SO3) (Wako Pure Chemicals) The mixture was reacted at 100 ° C. for 10 hours. Thereafter, the mixture was poured little by little into a large amount of water, neutralized with NaOH, and 200 g of sodium chloride was added to precipitate the composite. The resulting precipitate was filtered off and recrystallized with an aqueous ethanol solution to obtain disodium 3,3′-disulfonate-4,4′-difluorobenzophenone.

[Reference Example 1: Production Example of Polymer Electrolyte Solution A]
129 g of monomer 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane having a solubility-imparting group synthesized in Synthesis Example 1 in a 5 L reaction vessel equipped with a stirrer, nitrogen introduction tube, and Dean-Stark trap , 4,4′-biphenol 93 g (Aldrich reagent) and 422 g (1.0 mol) of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone which is a monomer containing the ionic group synthesized in Synthesis Example 2 ), And after nitrogen substitution, 3000 g of N-methyl-2-pyrrolidone (NMP), 450 g of toluene, and 232 g of 18-crown-6 (Wako Pure Chemical Reagent) as a polymerization stabilizer were added, and it was confirmed that all the monomers were dissolved. Then, 304 g of potassium carbonate (Aldrich reagent) was added, dehydrated at 160 ° C. while refluxing, and heated to increase the temperature. And ene removed and subjected to 1 hour desalting polycondensation 200 ° C.. The obtained polymer had an ionic group density of 3.52 mmol / g and a weight average molecular weight of 320,000.

Next, NMP is added and diluted so that the viscosity of the polymerization stock solution becomes 0.5 Pa · s, and an inverter / compact high-speed cooling centrifuge manufactured by Kubota Manufacturing Co., Ltd. (Model No. 6930 is set with an angle rotor RA-800, 25 ° C., 30 ° C.) The polymerization stock solution was directly centrifuged at a centrifugal force of 20000 G) for a minute. Since the precipitated solid (cake) and the supernatant (coating solution) could be separated cleanly, the supernatant was recovered. Next, it is distilled under reduced pressure at 80 ° C. while stirring, NMP is removed until the polymer concentration reaches 20% by weight, and further filtered under pressure through a 5 μm filter made of polytetrafluoroethylene (PTFE) to give a polymer electrolyte solution A. Got.
[Reference Example 2: Production Example of Polymer Electrolyte Solution B]
A reflux condenser connected with a stirrer, a thermometer and a calcium chloride tube was attached, and the inside of a 500 ml four-necked round bottom flask was purged with nitrogen, and then 25 g of polyethersulfone (PES) and 125 ml of concentrated sulfuric acid were added. The mixture was stirred overnight at room temperature under a nitrogen stream to obtain a homogeneous solution. To this solution, 48 ml of chlorosulfuric acid was added dropwise from a dropping funnel while stirring under a nitrogen stream. Since the chlorosulfuric acid reacted vigorously with the water in the concentrated sulfuric acid for a while after the start of dripping and foamed, it was dripped slowly, and after the foaming became gentle, the dripping was completed within 5 minutes. The reaction solution after completion of the dropwise addition was sulfonated by stirring at 25 ° C. for 4 hours.

  The reaction solution was then slowly added dropwise to 15 liters of deionized water to precipitate sulfonated polyethersulfone and collected by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 80 ° C. overnight. The resulting sulfonated polyethersulfone had an ionic group density of 2.0 mmol / g. This sulfonated polyethersulfone was dissolved in NMP so that the polymer concentration was 20% by weight to obtain a polymer electrolyte solution B.

[Reference Example 3: Production Example of Polymer Electrolyte Solution C]
A reflux condenser connected with a stirrer, thermometer and calcium chloride tube was attached, and the inside of the 500 ml four-necked round bottom flask was purged with nitrogen, and then 25 g of polyphenylene sulfide (Torayna (registered trademark) manufactured by Toray) and concentrated 100 ml of sulfuric acid was added. The mixture was stirred overnight at room temperature under a nitrogen stream to obtain a homogeneous solution. To this solution, 48 ml of chlorosulfuric acid was added dropwise from a dropping funnel while stirring under a nitrogen stream. Since the chlorosulfuric acid reacted vigorously with the water in the concentrated sulfuric acid for a while after the start of dripping and foamed, it was dripped slowly, and after the foaming became gentle, the dripping was completed within 5 minutes. The reaction solution after completion of the dropwise addition was sulfonated by stirring at 25 ° C. for 4 hours.

  The reaction solution was then slowly added dropwise to 15 liters of deionized water to precipitate sulfonated polyphenylene sulfide, which was collected by filtration. The deposited precipitate was repeatedly washed with deionized water using a mixer and collected by suction filtration until the filtrate became neutral, and then dried under reduced pressure at 80 ° C. overnight. The resulting sulfonated polyphenylene sulfide had an ionic group density of 2.0 mmol / g. This sulfonated polyphenylene sulfide was dissolved in NMP so that the polymer concentration was 20% by weight to obtain a polymer electrolyte solution C.

[Reference Example 4: Production Example of Fluorinated Polymer Porous Material A (Nonwoven Fabric)]
10 g of ethylene glycol was added to 100 g of a Nafion (registered trademark) solution of Aldrich reagent (Prod. No. 663492) to obtain a spinning dope. Next, using an electrospinning unit manufactured by Kato Tech Co., Ltd., voltage 35 kV, syringe pump discharge speed 0.05 cc / min, traverse speed 50 mm / min, drum type target (diameter 100 mm) peripheral speed 0.8 m / min, syringe Electrospinning was performed under the condition that the distance between the target and the target was 100 mm.

  The average diameter of the obtained fluorine-containing polymer fibers was 600 nm, and the fibers were collected on a target to obtain a nonwoven fabric made of a perfluorocarbon polymer material containing an ionic group having a thickness of 10 μm.

[Reference Example 5: Production Example of Fluorinated Polymer Porous Material B (Porous Film)]
A polytetrafluoroethylene porous film having a thickness of 20 μm and a porosity of 50% was sulfonated by being kept in 100% anhydrous sulfuric acid gas at 100 ° C. for 24 hours. The obtained film was washed three times with boiling distilled water to obtain a porous film made of a perfluorocarbon polymer material containing an ionic group.

Example 1
The polymer electrolyte solution A of Reference Example 1 was cast and applied onto a 125 μm PET film (“Lumirror (registered trademark)” manufactured by Toray Industries, Inc.), and “Poreflon (registered trademark) membrane” manufactured by Sumitomo Electric ”PTFE-based fluoropolymer porous material that does not contain ionic groups and has a model number HPW-045-30 (hydrophilic film) stretched twice in the vertical and horizontal directions and processed to a thickness of 15 μm and a porosity of 70% is bonded. Then, the polymer electrolyte solution A was impregnated in the voids of the fluoropolymer porous body.

  Next, it was put into a hot air dryer, and the solvent was removed by drying at 100 ° C. for 10 minutes and at 150 ° C. for 20 minutes. Next, it is immersed in a 10% by weight sulfuric acid aqueous solution at 40 ° C. for 30 minutes while remaining attached to the PET substrate to remove proton exchange and solubility-imparting groups of the polymer electrolyte, and is washed until the washing water becomes neutral. And after re-drying at 60 ° C., it was peeled off from the PET substrate to obtain a composite polymer electrolyte membrane A. The content of the aromatic hydrocarbon material having ionic groups in the composite layer composed of the aromatic hydrocarbon material having ionic groups and the fluoropolymer porous material was 59% by weight.

The ionic group density of this composite polymer electrolyte membrane A was 2.4 mmol / g. Using this composite polymer electrolyte membrane A, the dimensional change was measured and found to be 1.1%. The tensile strength at break when wet was 50 MPa. The output of the fuel cell using the composite polymer electrolyte membrane A under low humidification was 0.58 V, and the hydrogen permeation current before and after the power generation durability evaluation test was measured. after assessed in cm ^2, it was good and durable a 0.85mA / cm ^2.

Example 2
The polymer electrolyte solution A of Reference Example 1 was cast on a 125 μm PET film (“Lumirror (registered trademark)” manufactured by Toray Industries, Inc.), and the fluorine-containing polymer obtained in Reference Example 4 was then formed thereon. The porous body A (nonwoven fabric) was bonded, and the polymer electrolyte solution A was impregnated into the voids of the fluorine-containing polymer porous body A (nonwoven fabric). Thereafter, the same procedure as in Example 1 was performed to obtain a composite polymer electrolyte membrane B. The content of the aromatic hydrocarbon material having an ionic group in the composite layer composed of the aromatic hydrocarbon material having an ionic group and the fluoropolymer porous material was 55% by weight.

The ionic group density of this composite polymer electrolyte membrane B was 3.0 mmol / g. Using this composite polymer electrolyte membrane B, the dimensional change was measured and found to be 2.0%, and the tensile strength at break when wet was 40 MPa. In addition, the output of the fuel cell using the composite polymer electrolyte membrane B under low humidification is 0.62 V, and the hydrogen permeation current before and after the power generation durability evaluation test was measured. after assessed in cm ^2, it was good and durable a 0.65mA / cm ^2.

Example 3
The same procedure as in Example 1 was conducted except that the fluoropolymer porous material B (porous film) obtained in Reference Example 5 was used instead of the fluoropolymer porous material of Example 1, and the composite high A molecular electrolyte membrane C was obtained. The content of the aromatic hydrocarbon material having an ionic group in the composite layer composed of the aromatic hydrocarbon material having an ionic group and the fluoropolymer porous material was 30% by weight.

The ionic group density of this composite polymer electrolyte membrane C was 2.9 mmol / g. When this composite polymer electrolyte membrane C was used and the dimensional change rate was measured, it was 2.0%, and the tensile strength at break when wet was 40 MPa. In addition, the output of the fuel cell using the composite polymer electrolyte membrane B under low humidification is 0.61 V, and the hydrogen permeation current before and after the power generation durability evaluation test was measured. after assessed in cm ^2, it was good and durable a 0.77mA / cm ^2.

Comparative Example 1
The composite polymer electrolyte was prepared in the same manner as in Example 1 except that a commercially available polyolefin porous film ("Celguard" (registered trademark)) was used without using the fluoropolymer porous material of Example 2. Membrane D was obtained. The content of the aromatic hydrocarbon material having an ionic group in the composite layer composed of the aromatic hydrocarbon material having an ionic group and the fluorine-containing polymer porous material was 40% by weight.

The ionic group density of this composite polymer electrolyte membrane D was 1.4 mmol / g. Using this composite polymer electrolyte membrane D, the dimensional change was measured and found to be 1.2%. The tensile strength at break when wet was 65 MPa. Further, the output of the fuel cell using the composite polymer electrolyte membrane D under low humidification was 0.35 V, and the power generation performance was insufficient. The measured hydrogen permeation currents before and after the power generation durability evaluation test, before evaluation after the evaluation in 0.5 mA / cm ² was inferior also Durability 10.2mA / cm ^2.

Example 4
The fiber collection time of Reference Example 4 was adjusted to obtain a nonwoven fabric made of a perfluorocarbon polymer material containing an ionic group having a thickness of 10 μm. Using this, it carried out similarly to Example 2, and obtained the composite polymer electrolyte membrane E. The content of the aromatic hydrocarbon material having an ionic group in the composite layer composed of the aromatic hydrocarbon material having an ionic group and the fluoropolymer porous material was 95% by weight.

The ionic group density of this composite polymer electrolyte membrane E was 3.3 mmol / g. Using this composite polymer electrolyte membrane E, the dimensional change rate was measured and found to be 4.0%, and the tensile strength at break when wet was 48 MPa. The output of the fuel cell using the composite polymer electrolyte membrane E under low humidification is 0.63 V, and the hydrogen permeation current before and after the power generation durability evaluation test is measured. after evaluation at / cm ² is durability a 0.7mA / cm ² was poor.

Comparative Example 2
The same procedure as in Example 1 was carried out except that the “Poreflon (registered trademark) membrane” model number PW-045-30 (hydrophobic membrane) manufactured by Sumitomo Electric was used as it was without using the fluoropolymer porous material of Example 1. As a result, a composite polymer electrolyte membrane F was obtained. An aromatic hydrocarbon material having an ionic group in a composite layer composed of an aromatic hydrocarbon material having an ionic group and a fluorine-containing polymer porous body that repels NMP because it has not been subjected to a hydrophilic treatment The content of was 15% by weight.

  The ionic group density of this composite polymer electrolyte membrane F was 1.2 mmol / g. Using this composite polymer electrolyte membrane F, the dimensional change was measured and found to be 1.2%. The tensile strength at break when wet was 45 MPa. Further, the output of the fuel cell using the composite polymer electrolyte membrane F under low humidification was 0.21 V, and the power generation performance was insufficient.

Example 5
The polymer electrolyte solution B of Reference Example 2 was cast and applied onto a 125 μm PET film (“Lumirror (registered trademark)” manufactured by Toray Industries, Inc.), and on top of that, the polymer electrolyte solution B obtained in Reference Example 4 was obtained. The fluorine-containing polymer porous body A (nonwoven fabric) was bonded together, and the polymer electrolyte solution B was impregnated in the voids of the fluorine-containing polymer porous body A (nonwoven fabric). Next, it was put into a hot air dryer, and the solvent was dried and removed at 100 ° C. for 10 minutes and 150 ° C. for 20 minutes, and peeled off from the PET substrate to obtain a composite polymer electrolyte membrane G. The content of the aromatic hydrocarbon material having an ionic group in the composite layer composed of the aromatic hydrocarbon material having an ionic group and the fluorine-containing polymer porous material was 70% by weight.

The ionic group density of this composite polymer electrolyte membrane G was 1.9 mmol / g. Using this composite polymer electrolyte membrane A, the dimensional change rate was measured and found to be 1.1%, and the tensile strength at break when wet was 55 MPa. The output of the fuel cell using the composite polymer electrolyte membrane G under low humidification was 0.55 V, and the hydrogen permeation current before and after the power generation durability evaluation test was measured. after assessed in cm ^2, it was good and durable a 0.90mA / cm ^2.

Example 6
A composite polymer electrolyte membrane H was obtained in the same manner as in Example 4 except that the polymer electrolyte solution B was changed to the polymer electrolyte solution C of Reference Example 3.

  The content of the aromatic hydrocarbon material having an ionic group in the composite layer composed of the aromatic hydrocarbon material having an ionic group and the fluorine-containing polymer porous material was 70% by weight.

The ionic group density of this composite polymer electrolyte membrane H was 1.8 mmol / g. Using this composite polymer electrolyte membrane H, the dimensional change was measured and found to be 1.0%. The tensile strength at break when wet was 60 MPa. The output of the fuel cell using the composite polymer electrolyte membrane H under low humidification is 0.56 V, and the hydrogen permeation current before and after the power generation durability evaluation test was measured. after assessed in cm ^2, it was good and durable a 0.85mA / cm ^2.

Example 7
PVDF (Kureha Chemical Co., Ltd. # 1100) not containing ionic groups was dissolved in N, N-dimethylformamide to obtain a PVDF solution having a solid content of 5 wt%. Next, using an electrospinning unit manufactured by Kato Tech Co., Ltd., voltage 35 kV, syringe pump discharge speed 0.05 cc / min, traverse speed 50 mm / min, drum type target (diameter 100 mm) peripheral speed 0.8 m / min, syringe Electrospinning was performed under the condition that the distance between the target and the target was 100 mm.

  The average diameter of the obtained PVDF fibers was 500 nm, and the fibers were collected on a target to obtain a PVDF nonwoven fabric having a thickness of 5 μm and a porosity of 94%.

Next, the PVDF nonwoven fabric was put in a sealed container, nitrogen gas containing 5% F ₂ was supplied at normal pressure, and the mixture was left at 60 ° C. for 30 minutes. Thereafter, the treated nonwoven fabric was taken out to obtain a fluoropolymer porous body C (nonwoven fabric). When this fluoropolymer porous body C (nonwoven fabric) was immersed in N, N-dimethylformamide and N-methyl-2-pyrrolidone, it was confirmed that it did not dissolve.

  In addition, the poor solubility in this application was judged as follows. The fluorine-containing polymer porous body C (nonwoven fabric) cut into 5 cm square was dried at 80 ° C. for 8 hours under reduced pressure for 8 g, and the weight of the fluorine-containing polymer porous body C (nonwoven fabric) was 100 ml of 60 ° C. N-methyl. After being immersed in -2-pyrrolidone for 2 hours and taken out under reduced pressure at 80 ° C. for 8 hours as Yg, Y / W ≧ 0.8, it was judged as poorly soluble.

  Further, it was confirmed that this fluoropolymer porous body C (nonwoven fabric) was a nonwoven fabric containing a PTFE skeleton in which hydrogen of PVDF was replaced with F by total reflection Fourier transform infrared spectroscopy (ATR-FTIR). .

  Using this fluorine-containing polymer porous body C (nonwoven fabric) instead of the fluorine-containing polymer porous body of Example 1, composite film formation was carried out in the same manner as in Example 1 to prepare composite polymer electrolyte membrane I. Obtained. The content of the aromatic hydrocarbon material having an ionic group in the composite layer composed of the aromatic hydrocarbon material having an ionic group and the fluoropolymer porous material was 85% by weight.

The ionic group density of this composite polymer electrolyte membrane I was 2.6 mmol / g. When this composite polymer electrolyte membrane I was used and the dimensional change rate was measured, it was 1.2%, and the tensile strength at break when wet was 48 MPa. The output of the fuel cell using the composite polymer electrolyte membrane I under low humidification was 0.62 V, and the hydrogen permeation current before and after the power generation durability evaluation test was measured. after assessed in cm ^2, it was good and durable a 0.805mA / cm ^2.

  The composite polymer electrolyte membrane of the present invention can be applied to various electrochemical devices (for example, fuel cells, water electrolysis devices, chloroalkali electrolysis devices, etc.). Among these devices, it is suitable for a fuel cell, particularly suitable for a fuel cell using hydrogen or a methanol aqueous solution as a fuel, a mobile phone, a personal computer, a PDA, a video camera (camcorder), a digital camera, a handy terminal, an RFID reader. , Digital audio players, portable devices such as various displays, electric appliances such as electric shavers and vacuum cleaners, electric tools, household power supply machines, cars such as passenger cars, buses and trucks, motorcycles, forklifts, electric assist bicycles, electric It is preferably used as a power supply source for a cart, an electric wheelchair, a moving body such as a ship and a railway, various robots, and a cyborg. Especially in portable devices, it is used not only for power supply sources, but also for charging secondary batteries installed in portable devices, and also suitable as a hybrid power supply source used in combination with secondary batteries, capacitors, and solar cells. Available to:

Claims (9)

A composite layer comprising an aromatic hydrocarbon material having an ionic group and a fluorine-containing polymer porous material, wherein the content of the aromatic hydrocarbon material having an ionic group in the composite layer is 20% by weight A composite polymer electrolyte membrane characterized by being 95% by weight or less. The composite polymer electrolyte membrane according to claim 1, wherein the fluoropolymer porous body is a porous film made of a fluoropolymer material. The composite polymer electrolyte membrane according to claim 1, wherein the fluoropolymer porous material is a nonwoven fabric having an average fiber diameter of 10 µm or less made of a fluoropolymer material. The composite polymer electrolyte membrane according to claim 2 or 3, wherein the fluorine-containing polymer material is a perfluorocarbon-based polymer material containing an ionic group. The composite polymer electrolyte membrane according to claim 2 or 3, wherein the fluorine-containing polymer material contains a polytetrafluoroethylene skeleton. The composite polymer electrolyte membrane according to any one of claims 1 to 5, wherein the aromatic hydrocarbon-based material having an ionic group contains an ionic group exceeding 2.0 mmol / g. The aromatic hydrocarbon polymer material containing an ionic group has one or two or more units selected from polyether ketone, polyether ether ketone, polyether sulfone, and polyphenylene sulfide. The composite polymer electrolyte membrane according to any one of the above. The composite polymer electrolyte membrane according to claim 3, wherein a nonwoven fabric made of a fluorine-containing polymer material and having an average fiber diameter of 10 µm or less is produced by a production method including the following steps.
(1) Step of dissolving fluorine-containing polymer precursor material in solvent (2) Step of electrospinning the solution of fluorine-containing polymer precursor material (3) Fluorine-containing polymer precursor by collecting electrospun fibers Step of making material nonwoven fabric (4) Step of bringing the fluorine-containing polymer precursor material nonwoven fabric into contact with a gas containing F ₂ to make a fluorine-containing polymer material nonwoven fabric The composite polymer electrolyte membrane according to claim 8, wherein the fluorine-containing polymer precursor material is a material containing at least polyvinylidene fluoride.