Resin composition, method for producing resin composition, and electrochemical device

Abstract

The problem addressed by the present invention is to provide an anion conductive electrolyte membrane and a binder for anion conduction, which are excellent in terms of alkali resistance at high temperatures and gas barrier properties. The second problem addressed by the present invention is to provide a resin composition which promotes graft polymerization of a base material that is composed of an aromatic hydrocarbon-based polymer, and which has a high graft ratio with respect to the base material. In order to solve the problem, the present invention provides a resin composition which uses an aromatic hydrocarbon-based polymer as a base material and has a graft polymer chain on the base material, and which is characterized in that the graft polymer chain has a cationic functional group. In order to solve the second problem, the present invention provides a method for producing a resin composition which uses an aromatic hydrocarbon-based polymer as a base material, the method being characterized by including a pretreatment step in which the base material is immersed in a solvent.

Description

Resin composition, method for producing resin composition, and electrochemical device

[0001] The present invention relates to a resin composition and a method for producing the resin composition. The present invention also relates to an electrochemical device using the resin composition as a material for an electrolyte layer and / or an electrode.

[0002] In general, it is common to design the structural units of a resin composition and impart desired functions to the resin composition, and it is also common to use functional resin compositions as materials for various devices.

[0003] An example of a device using the functional resin composition is an electrochemical device that converts electrical energy and chemical energy, and a specific example of the use of the functional resin composition is as one of the materials for an electrolyte layer (electrolyte membrane) or an electrode in the electrochemical device.

[0004] Fuel cells and metal-air batteries are known as such electrochemical devices. Fuel cells and metal-air batteries use air (oxygen, water) as the active material on the positive electrode side and convert the energy generated by a chemical reaction with the active material (fuel, metal, etc.) on the negative electrode side into electrical energy, which has the advantage of high energy conversion efficiency. Among these, solid polymer fuel cells in particular have low operating temperatures and low electrolyte resistance, and can produce high output even in a small size due to the use of highly active catalysts, and are expected to be put into practical use soon.

[0005] For example, proton-conducting fuel cells, which use hydrogen as fuel, have high power generation efficiency and are a promising solution to the depletion of fossil fuels. In addition, they can significantly reduce carbon dioxide emissions, making them a means of curbing global warming. Therefore, there is a desire to develop them as a power source for home cogeneration and automobiles.

[0006] In recent years, attention has been focused on non-platinum anion-conducting fuel cells, which can use fuels other than hydrogen, such as methanol and hydrazine hydrate, and have been reported to exhibit output three times higher than that of proton-conducting fuel cells. Because of their ease of installation as a liquid fuel, safety, and high output density, anion-conducting fuel cells are being considered for use in fuel cell vehicles, particularly those designed for compact cars, and as disaster-response power sources for wireless base stations and other applications. Furthermore, anion-conducting fuel cells do not require the strongly acidic conditions required for operation, and their greatest advantage is that they can use inexpensive materials such as iron and cobalt, which dissolve under strongly acidic conditions and are therefore not compatible with proton-conducting fuel cells, rather than precious metals like platinum, for their electrodes. Therefore, low-cost, high-output fuel cells are expected.

[0007] In such anion conduction fuel cells, the electrolyte membrane for anion conduction fuel cells (hereinafter referred to as the "anion conduction electrolyte membrane") functions as both an "electrolyte" for conducting hydroxide ions (anions) and a "diaphragm" for preventing direct mixing of the fuels, methanol and hydrazine, with oxygen. For this reason, anion conduction electrolyte membranes are required to have high ionic conductivity, chemical stability and heat resistance sufficient to withstand long-term use in alkaline aqueous solutions at high temperatures (>60°C), which are the operating conditions of the cell, and a consistent water retention capacity to maintain high ionic conductivity. On the other hand, their role as a diaphragm requires excellent mechanical strength and dimensional stability, as well as high barrier properties against methanol, hydrazine, and oxygen. However, few anion conduction electrolyte membranes suitable for practical use have been developed. Compared to established proton conduction electrolyte membranes, such as Nafion®, current anion conduction electrolyte membranes have poor performance in terms of electrical conductivity, mechanical strength, fuel permeability, and other characteristics, as well as significantly poor alkali resistance, resulting in a major durability issue.

[0008] To address these issues, active efforts have been made to develop anion exchange membranes. For example, anion exchange membranes have been developed using a hydrocarbon-based film such as porous polyethylene as a substrate, with the pores filled with a crosslinked anion exchange resin (Patent Documents 1 to 3). Other methods have been proposed, including a method for manufacturing anion exchange membranes in which an alkylammonium salt is introduced by quaternization using a polymerized mixture of haloalkylstyrene, elastomer, and epoxy compound as a substrate membrane (Patent Document 4), and a method for manufacturing anion exchange membranes in which an anion exchange group precursor monomer is subjected to radiation-induced graft polymerization onto a fluoropolymer substrate and then an alkylammonium salt is introduced (Patent Document 5). Another method for manufacturing anion exchange membranes has been proposed in which an anion exchange membrane is attached to a fluoropolymer substrate by radiation-induced graft polymerization (Patent Document 6).

[0009] On the other hand, in the field of proton-conducting fuel cells, proton-conducting electrolyte membranes have been developed that use aromatic hydrocarbons as the substrate for electrolyte membranes for proton-conducting fuel cells (hereinafter referred to as "proton-conducting electrolyte membranes"), which have superior mechanical properties at high temperatures and fuel barrier properties compared to fluorine-based substrates. For example, in the case of proton-conducting electrolyte membranes using aromatic hydrocarbons as the substrate, a method for producing a proton-type electrolyte membrane has been proposed in which proton-conducting graft chains are introduced into a substrate made of an aromatic hydrocarbon-based polymer by radiation-induced graft polymerization of styrenesulfonic acid ethyl ester (Patent Documents 7 and 8).

[0010] Japanese Patent Laid-Open No. 2002-367626 Japanese Patent Laid-Open No. 2009-203455 Japanese Patent Laid-Open No. 2019-518809 Japanese Patent Laid-Open No. 2011-202074 Japanese Patent Laid-Open No. 2000-331693 Japanese Patent Laid-Open No. 2014-049352 Japanese Patent Laid-Open No. 2014-032952 Japanese Patent Laid-Open No. 2016-195047

[0011] In existing graft-type anion exchange membranes, the base material is a fluorine-based polymer such as ethylene tetrafluoroethylene copolymer (ETFE) or a hydrocarbon-based polymer such as polyethylene. These membrane materials lack sufficient mechanical strength for practical use, resulting in membrane rupture and other problems early in fuel cell testing. Furthermore, in ETFE-based graft-type anion exchange membranes, electrolyte membranes quaternized with trimethylamine undergo a graft chain elimination reaction under alkaline operating conditions, resulting in decreased ionic conductivity and reduced mechanical strength, leading to membrane breakage and other problems, preventing sufficient output and durability in fuel cell tests. Furthermore, fluorine-based polymers and hydrocarbon-based polymers have poor gas barrier properties, resulting in fuel loss and preventing their widespread use. Furthermore, in proton-conducting fuel cells, Nafion solution is commercially available as a binder for membrane electrode assemblies consisting of an electrolyte membrane, a catalyst, and a binder. However, in anion-conducting fuel cells, an anion-conducting binder with excellent alkaline resistance for alkaline fuel cells is not commercially available. The above-mentioned literature examples also use a structure similar to that of an anion exchange electrolyte membrane, and are insufficient in both performance and durability. Therefore, there is a demand for an anion exchange electrolyte membrane that has excellent alkali resistance at high temperatures and gas barrier properties, as well as a binder for anion conduction.

[0012] That is, an object of the present invention is to provide an anion exchange electrolyte membrane and a binder for anion conduction that are excellent in alkali resistance at high temperatures and gas barrier properties.

[0013] In another aspect of the present invention, a substrate made of an aromatic hydrocarbon-based polymer has excellent alkali resistance at high temperatures and gas barrier properties, but also has chemical resistance, which makes it difficult to introduce other monomers into the substrate by graft polymerization, etc. Therefore, a second object of the present invention is to provide a resin composition that promotes graft polymerization of a substrate made of an aromatic hydrocarbon-based polymer and has a high graft rate to the substrate.

[0014] A resin composition according to one aspect of the present invention is a resin composition having an aromatic hydrocarbon-based polymer as a base material and having graft polymer chains on the base material, wherein the graft polymer chains have cationic functional groups.

[0015] A method for producing a resin composition according to one aspect of the present invention is a method for producing a resin composition using an aromatic hydrocarbon-based polymer as a base material, and is characterized by comprising: a pretreatment step of immersing the base material in a solvent; a radiation irradiation step of irradiating the pretreated base material obtained by the pretreatment step with radiation; and a graft polymerization step of graft polymerizing a vinyl monomer onto the base material irradiated by the radiation irradiation step.

[0016] An electrochemical device according to one aspect of the present invention is an electrochemical device comprising an electrolyte layer and two electrodes arranged opposite each other with the electrolyte layer sandwiched therebetween, characterized in that the electrolyte layer and / or the electrodes comprise the resin composition according to the aspect of the present invention described above.

[0017] According to the present invention, it is possible to provide an anion exchange electrolyte membrane and an anion conduction binder that are excellent in alkali resistance at high temperatures and gas barrier property, and also to provide a resin composition that promotes graft polymerization of a substrate made of an aromatic hydrocarbon polymer and has a high graft rate to the substrate.

[0018] 3A is a graph showing the results of a tensile test after immersion in 1 M KOH at 80°C. FIG. 3B is a graph showing the change in membrane shape before and after an alkali resistance test. FIG. 3B is a graph showing measurement results obtained in an output test of an electrochemical device in an example of the present invention. In the figure, the white plots show a graph of current density-output density, and the black plots show a graph of current density-cell voltage. FIG. 3C is a graph showing the results obtained in an accelerated alkali resistance test of anion exchange electrolyte membranes in examples of the present invention and comparative examples.

[0019] Hereinafter, embodiments of the resin composition, the method for producing the resin composition, and the electrochemical device of the present invention will be described in detail. Note that the resin composition, the method for producing the resin composition, and the electrochemical device described in the embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention.

[0020] [Resin Composition] The resin composition according to an embodiment of the present invention is a resin composition having an aromatic hydrocarbon-based polymer as a base material and graft polymer chains on the base material, characterized in that the graft polymer chains have cationic functional groups. This resin composition has an aromatic hydrocarbon-based polymer as a base material, which has excellent alkali resistance at high temperatures and gas barrier properties, and has graft polymer chains having cationic functional groups, so that an anion exchange electrolyte membrane having excellent alkali resistance at high temperatures and gas barrier properties can be provided.

[0021] Aromatic hydrocarbon-based polymers are so-called super engineering plastics, possessing excellent heat resistance and chemical resistance and high mechanical strength. For example, aromatic hydrocarbon-based polymers having structures such as polyetheretherketone, polyethylene naphthalate, polycarbonate, polyetherketone, polyethersulfone, polyphenylene sulfide, polysulfone, or polyimide-based polymers such as polyimide, polyetherimide, polyamideimide, polybenzimidazole, and polyetheretherimide can also be used. Among these, aromatic hydrocarbon-based polymers having a polyetheretherketone structure, a polyetherketone structure, a polyimide structure, a polysulfone structure, or a polybenzimidazole structure are preferred. In these cases, a polymer electrolyte membrane can be produced that retains the excellent mechanical, thermal, and chemical properties of aromatic hydrocarbon-based polymers. Among these, polyetheretherketone (PEEK) is particularly preferred.

[0022] The substrate preferably has a lamellar structure. The lamellar structure can be formed by annealing the substrate. Annealing treatments include annealing by heating and annealing by solvent immersion, but annealing by solvent immersion is preferred. Annealing by solvent immersion can obtain a lamellar structure with a period of 8 to 9 nm, which can promote graft polymerization.

[0023] The shape of the substrate is not particularly limited, but a film shape is preferred, for example. The thickness of the polymer film as the substrate is not particularly limited, but 10 to 200 μm is preferred. If the thickness is greater than 10 μm, the strength of the resulting electrolyte membrane is improved, and if the thickness is less than 200 μm, the membrane resistance of the resulting electrolyte membrane is reduced, resulting in excellent properties for fuel cells, etc.

[0024] The graft polymer chain in the resin composition of the present invention is not particularly limited as long as it has a cationic functional group. The graft polymer chain having a cationic functional group may be formed by grafting a vinyl monomer having a cationic functional group onto the polymer main chain of the substrate, or by grafting a vinyl monomer onto the polymer main chain of the substrate and then introducing a cationic functional group into the graft polymer chain. By using a nonionic monomer as the vinyl monomer, excellent affinity with aromatic hydrocarbon polymers can be achieved, thereby improving the graft rate.

[0025] The graft polymer chains may form a graft polymer chain that is grafted to the substrate and a second graft polymer chain that is grafted to this graft polymer chain.

[0026] The graft ratio of the graft polymer chains to the substrate is not particularly limited, but is, for example, 30% or more, preferably 40% or more, more preferably 50% or more, even more preferably 55% or more, and particularly preferably 60% or more.

[0027] As the vinyl monomer, for example, a compound represented by the following chemical formula (1) is preferred. (R １ is an organic group having 1 to 6 carbon atoms, and X is a halogen atom.

[0028] R in chemical formula (1) １ is preferably a hydrocarbon group having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 3 carbon atoms, and even more preferably a methylene group. X in chemical formula (1) is preferably a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and more preferably a chlorine atom.

[0029] The cationic functional group can be introduced, for example, by a quaternization reaction into the compound represented by chemical formula (1). An example of the quaternization reaction is a reaction in which the X atom of the compound represented by chemical formula (1) is substituted with an amine compound. Examples of the amine compound include triethylamine and tetramethylimidazole.

[0030] The resin composition of the present invention preferably has a breaking strength of 40 MPa or more after immersion for 5 hours in a 1 M aqueous potassium hydroxide solution at 80° C. The breaking strength is preferably 50 MPa or more, more preferably 60 MPa or more, even more preferably 65 MPa or more, and particularly preferably 70 MPa or more.

[0031] (Method for Producing Resin Composition) A method for producing a resin composition according to an embodiment of the present invention is a method for producing a resin composition using an aromatic hydrocarbon-based polymer as a base material, and is characterized by comprising: a pretreatment step of immersing the base material in a solvent; a radiation irradiation step of irradiating the pretreated base material obtained by the pretreatment step with radiation; and a graft polymerization step of graft polymerizing a vinyl monomer onto the base material irradiated by the radiation irradiation step. According to this method for producing a resin composition, the immersion treatment using a solvent forms a lamellar structure in the aromatic hydrocarbon-based polymer base material, thereby improving the graft rate of the aromatic hydrocarbon-based polymer to the base material.

[0032] <Pretreatment Step> The pretreatment step is a process for immersing the substrate in a solvent. Immersing the substrate in a solvent forms a lamellar structure in the aromatic hydrocarbon polymer of the substrate, which has the effect of accelerating graft polymerization and improving the graft rate.

[0033] The solvent used in the pretreatment step is not particularly limited, and examples thereof include long-chain ethers or alcohols thereof such as ethylene glycol, ethylene glycol monomethyl ether, monoethylene glycol dimethyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol, and glycerol, as well as dichloroethane, chloroform, N-methylformaldehyde, N-methylacetamide, N-methylpyrrolidone, γ-butyrolactone, n-hexane, dioxane, methanol, ethanol, 1-propanol, tert-butanol, toluene, xylene, cyclohexane, cyclohexanone, and dimethyl sulfoxide. Among these, long-chain ethers or alcohols thereof are preferred.

[0034] The immersion conditions are not particularly limited, but the immersion temperature is usually room temperature (20° C.) or higher, preferably 40° C. or higher, more preferably 50° C. or higher, and usually 120° C. or lower, preferably 100° C. or lower, more preferably 80° C. or lower. The immersion time is usually 0.5 hours or longer, preferably 1 hour or longer, more preferably 2 hours or longer, and usually 100 hours or shorter, preferably 30 hours or shorter, more preferably 24 hours or shorter. Within the above ranges, sufficient annealing treatment is carried out to form a lamellar structure.

[0035] After the immersion treatment, a drying step for drying the substrate may be provided. In the drying step, the drying method is not particularly limited, and known drying methods such as air drying, vacuum drying, heat drying, and freeze drying can be applied. The drying conditions in the drying step are appropriately set depending on the drying method, and the drying temperature is, for example, usually room temperature (20°C) or higher and usually 80°C or lower. The drying time is, for example, usually 0.5 hours or longer, preferably 1 hour or longer, more preferably 2 hours or longer, and usually 100 hours or shorter, preferably 30 hours or shorter, and more preferably 24 hours or shorter.

[0036] <Radiation Irradiation Step> The radiation irradiation step is a process for irradiating the pretreated substrate obtained in the pretreatment step with radiation. The radiation irradiation step forms active sites in the aromatic hydrocarbon polymer, and the radiation-induced graft polymerization reaction is carried out in the graft polymerization step described below.

[0037] The radiation exposure step can be carried out by a known method such as a polymer radical method in which a polymer substrate is irradiated with radiation in an inert gas, or a peroxide method in which a polymer substrate is irradiated with radiation in the presence of oxygen.

[0038] The radiation used in the radiation irradiation step refers to ionizing radiation such as electron beams, gamma rays, and ion beams, and the energy amount of the radiation is usually 1 kGy or more, preferably 5 kGy or more, more preferably 10 kGy or more, and even more preferably 100 kGy or more, and usually 500 kGy or less, preferably 300 kGy or less, and more preferably 200 kGy or less. The temperature condition when irradiating with radiation is usually room temperature (20°C) or more and usually 150°C or less, preferably 50°C or less, and more preferably 30°C or less. Within the above range, sufficient ionic conductivity can be ensured and deterioration of the polymer-based material can be suppressed.

[0039] <Graft Polymerization Step> The graft polymerization step is a process for graft polymerizing a vinyl monomer onto the substrate that has been irradiated in the radiation irradiation step. The graft polymerization step is carried out by bringing the substrate into contact with the vinyl monomer.

[0040] The method for contacting the substrate with the monomer is not particularly limited, but examples thereof include a method of immersing the substrate after the radiation exposure step in a solution containing the monomer. The solvent used for the solution containing the monomer is not particularly limited, but examples thereof include long-chain ethers or alcohols thereof such as ethylene glycol, ethylene glycol monomethyl ether, monoethylene glycol dimethyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol, and glycerol, as well as dichloroethane, chloroform, N-methylformaldehyde, N-methylacetamide, N-methylpyrrolidone, γ-butyrolactone, n-hexane, dioxane, methanol, ethanol, 1-propanol, tert-butanol, toluene, xylene, cyclohexane, cyclohexanone, and dimethyl sulfoxide. Among these, long-chain ethers or alcohols thereof are preferred.

[0041] The concentration of the monomer in the solution is not particularly limited and can be appropriately set depending on the purpose. For example, the concentration of the monomer is usually 10% by weight or more, preferably 30% by weight or more, more preferably 40% by weight or more, and usually 100% by weight or less, preferably 80% by weight or less, more preferably 60% by weight or less.

[0042] The immersion temperature is usually room temperature (20°C) or higher, preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher, and usually 120°C or lower, preferably 100°C or lower. The immersion time is usually 0.5 hours or longer, preferably 1 hour or longer, more preferably 10 hours or longer, even more preferably 20 hours or longer, and particularly preferably 40 hours or longer, and usually 200 hours or shorter, preferably 100 hours or shorter. Within the above range, a sufficient graft rate can be ensured and deterioration of the substrate can be suppressed.

[0043] <Ionic Compound Introduction Step> The ionic compound introduction step is a step for introducing a compound having an ionic functional group into the graft polymer chain formed by the vinyl monomer. In addition to the step related to the radiation-induced graft polymerization described above, the method for producing a resin composition according to an embodiment of the present invention may also include a step for introducing an ionic compound to impart functions according to various applications to the resin composition according to an embodiment of the present invention. The compound having an ionic functional group may be a compound having a cationic group or a compound having an anionic group.

[0044] For example, in the ionic compound introduction step of introducing a compound having a cationic group, a quaternization reaction step of quaternizing the halogenated alkyl group formed in the graft polymer chain, or a halide ion (X － The process may include an ion exchange step to replace the anion of the cation with the desired anion.

[0045] The reaction yield of N-alkylation of the graft polymer chains obtained in the quaternization reaction step is usually 30% or more, preferably 50% or more, and more preferably 70% or more.

[0046] In the ion exchange step, the resulting resin composition is contacted with a solution containing a desired anion to exchange the desired anion (X － ) with a desired anion. For example, a resin composition that has undergone an N-alkylation step using an alkyl halide has a halogen ion as a counter ion. Therefore, when the resin composition is used as an anion exchange electrolyte membrane, it is preferable to replace the halogen ion as the counter ion with a hydroxide ion. In this case, the ion substitution step may be any step that involves contacting the resin composition with a solution containing hydroxide ions, and the specific method, conditions, etc. are not particularly limited, and known methods can be appropriately adopted.

[0047] Examples of solutions containing hydroxide ions include aqueous solutions of sodium hydroxide, potassium hydroxide, etc. The hydroxide ion concentration in the solution is usually 0.1 mol / L or more, preferably 0.5 mol / L or more, and usually 5 mol / L or less, more preferably 2 mol / L or less. The immersion temperature is usually 5°C or more, preferably 20°C or more, and usually 80°C or less, preferably 60°C or less. The immersion time is usually 2 hours or more, preferably 16 hours or more, and usually 48 hours or less, preferably 24 hours or less. In addition, it is desirable to replace the solution during immersion in order to complete the ion substitution step of the equilibrium reaction.

[0048] [Electrochemical Device] The resin composition according to the embodiment of the present invention described above can be suitably used as a material in an electrochemical device. In particular, the resin composition according to the embodiment of the present invention can be suitably used as a material for an electrolyte layer and / or electrodes in an electrochemical device including an electrolyte layer and two electrodes arranged opposite each other with the electrolyte layer sandwiched therebetween. Note that the "electrode material" may be any material that forms part of the structure related to the electrode, and also includes a binder for a catalyst or active material.

[0049] The electrochemical device of the present invention may be any device that includes an electrolyte layer and electrodes, and examples thereof include a fuel cell, a metal-air battery, and an electrolytic cell. In particular, the electrochemical device of the present invention is preferably a fuel cell or a metal-air battery. This makes it possible to fully utilize the high ionic conductivity and alkali resistance of the resin composition described above, overcome the problems of low output and durability that have been encountered with conventional fuel cells or metal-air batteries, and provide a highly practical fuel cell or metal-air battery. Hereinafter, the electrochemical device of the present invention will be mainly described in terms of a fuel cell, but is not limited thereto.

[0050] 1 is a schematic diagram illustrating the structure of an electrochemical device (fuel cell) according to an embodiment of the present invention. The electrochemical device 1 according to this embodiment is an anion-conducting fuel cell to which a liquid fuel component is directly supplied.

[0051] Examples of fuel components supplied to the electrochemical device 1 include hydrogen, methanol, ammonia, and hydrazines (including hydrazine hydrate, hydrazine anhydride, etc.).

[0052] 1, the electrochemical device 1 has a stack structure in which a plurality of fuel cell units (unit cells) are stacked, each unit cell including a membrane electrode assembly 2, a fuel-side diffusion layer 8, an oxygen-side diffusion layer 9, a fuel supply member 3 disposed on one side (anode side) of the membrane electrode assembly 2, and an air supply member 4 disposed on the other side (cathode side) of the membrane electrode assembly 2. In FIG. 1, only one of the plurality of unit cells is shown as the electrochemical device 1, and the other unit cells are omitted.

[0053] The membrane electrode assembly 2 includes an electrolyte membrane 5 as an electrolyte layer, a fuel-side electrode 6 consisting of a catalyst layer formed on one surface in the thickness direction of the electrolyte membrane 5 (hereinafter simply referred to as "one surface"), and an oxygen-side electrode 7 consisting of a catalyst layer formed on the other surface in the thickness direction of the electrolyte membrane 5 (hereinafter simply referred to as "other surface"). That is, the membrane electrode assembly 2 has a structure in which the fuel-side electrode 6 and the oxygen-side electrode 7 are arranged opposite each other with the electrolyte membrane 5 sandwiched therebetween.

[0054] The electrolyte membrane 5 contains an anion component (e.g., hydroxide ion (OH － The electrolyte membrane 5 is not particularly limited as long as it is a layer through which the anion component can migrate and has a function of allowing migration of the anion component. For example, the electrolyte membrane 5 may be formed using the resin composition described above.

[0055] The fuel-side electrode 6 comprises a catalyst layer formed from a cell electrode catalyst layer composition containing a binder for forming an electrode catalyst layer and a catalyst.

[0056] The catalyst is not particularly limited, and examples thereof include elements in Groups 8 to 10 (VIII) of the periodic table, such as platinum group elements (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt)), iron group elements (iron (Fe), cobalt (Co), nickel (Ni)), and elements in Group 11 (IB) of the periodic table, such as copper (Cu), silver (Ag), and gold (Au). These catalysts can be used alone or in combination of two or more.

[0057] The catalyst may also be supported on a catalyst carrier, such as a porous substance such as carbon or a ceramic material.

[0058] To form the catalyst layer of the fuel-side electrode 6, first, a catalyst ink (a solution containing a cell electrode catalyst layer composition) for the fuel-side electrode 6 is prepared.

[0059] To prepare the catalyst ink for the fuel-side electrode 6, a binder for forming an electrode catalyst layer is added to the above-mentioned catalyst and stirred.

[0060] Here, the above-mentioned resin composition can be used as the binder for forming the electrode catalyst layer. More specifically, the above-mentioned resin composition can be shredded or freeze-pulverized and dispersed in a solvent.

[0061] Examples of the solvent include known solvents such as lower alcohols such as methanol, ethanol, and 1-propanol, ethers such as tetrahydrofuran (THF) and dioxane, ketones such as acetone and methyl ethyl ketone, aprotic polar solvents such as N-methylpyrrolidone, and water. The stirring temperature is, for example, 10 to 30°C, and the stirring time is, for example, 1 to 60 minutes. These solvents can be used alone or in combination of two or more.

[0062] In this way, the catalyst ink for the fuel-side electrode 6 can be prepared.

[0063] The prepared catalyst ink for the fuel-side electrode 6 is then applied to a material that will serve as the electrode substrate and dried to form a catalyst layer. In this case, a porous body is preferably used as the material that will serve as the electrode substrate, and for example, the electrolyte membrane 5 or the fuel-side diffusion layer 8 may be used. In this case, the catalyst ink for the fuel-side electrode 6 is applied to one side of the electrolyte membrane 5 or the fuel-side diffusion layer 8 and dried to form a catalyst layer.

[0064] Examples of the method for applying the catalyst ink for the fuel-side electrode 6 include known application methods such as spraying, die coating, and ink-jet methods, and preferably, spraying.

[0065] The drying temperature is, for example, 10 to 40°C.

[0066] As a result, the fuel electrode 6 made of the catalyst layer can be obtained.

[0067] The oxygen-side electrode 7, like the fuel-side electrode 6, is composed of a catalyst layer formed from a cell electrode catalyst layer composition containing a binder for forming an electrode catalyst layer and a catalyst.

[0068] The catalyst for the oxygen-side electrode 7 may be the same as the catalyst for the fuel-side electrode 6 described above. Alternatively, the oxygen-side electrode 7 may be formed from, for example, a material in which a transition metal is supported on a composite of a complex-forming organic compound and / or a conductive polymer and carbon (hereinafter, this composite is referred to as a "carbon composite").

[0069] Examples of transition metals include scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), lanthanum (La), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au). These transition metals can be used alone or in combination of two or more.

[0070] The complex-forming organic compound is an organic compound that forms a complex with a metal atom by coordinating to the metal atom, and examples thereof include pyrrole, porphyrin, tetramethoxyphenylporphyrin, dibenzotetraazaannulene, phthalocyanine, choline, chlorine, phenanthroline, salcomine, benzimidazole, aminobenzimidazole, nicarbazin, diaminomaleonitrile, carbendazim, aminoantipyrine, etc., or polymers thereof. These complex-forming organic compounds can be used alone or in combination of two or more.

[0071] Examples of conductive polymers include compounds that overlap with the above-mentioned complex-forming organic compounds, such as polyaniline, polypyrrole, polythiophene, polyacetylene, polyvinylcarbazole, polytriphenylamine, polypyridine, polypyrimidine, polyquinoxaline, polyphenylquinoxaline, polyisothianaphthene, polypyridinediyl, polythienylene, polyparaphenylene, polyflurane, polyacene, polyfuran, polyazulene, polyindole, polydiaminoanthraquinone, etc. These conductive polymers can be used alone or in combination of two or more.

[0072] To form the catalyst layer for the oxygen-side electrode 7, a catalyst ink (a solution containing a cell electrode catalyst layer composition) for the oxygen-side electrode 7 is first prepared, in the same manner as in the case of forming the catalyst layer for the fuel-side electrode 6 described above.

[0073] The catalytic ink for the oxygen-side electrode 7 is prepared, for example, in the same manner as the catalytic ink for the fuel-side electrode 6 described above.

[0074] The catalyst ink for the oxygen-side electrode 7 may also be prepared, for example, by forming a carbon composite and then supporting a transition metal on the carbon composite.

[0075] To prepare the catalytic ink for the oxygen-side electrode 7, the above-mentioned binder for forming an electrode catalyst layer is added to the above-mentioned catalyst and stirred, in the same manner as in the preparation of the catalytic ink for the fuel-side electrode 6. In this way, the catalytic ink for the oxygen-side electrode 7 can be prepared.

[0076] Then, the prepared catalyst ink for the oxygen-side electrode 7 is applied to a material that will become the electrode substrate (e.g., the other surface of the electrolyte membrane 5 or one surface of the oxygen-side diffusion layer 9) in the same manner as the catalyst ink for the fuel-side electrode 6, and dried to form a catalyst layer.

[0077] As a result, the oxygen-side electrode 7 made of the catalyst layer can be obtained.

[0078] To manufacture the membrane electrode assembly 2, the fuel-side electrode 6 and the oxygen-side electrode 7 are bonded to the electrolyte membrane 5. At this time, the fuel-side diffusion layer 8 and the oxygen-side diffusion layer 9, which will be described later, may also be bonded.

[0079] The means for joining the fuel-side electrode 6 and the oxygen-side electrode 7 to the electrolyte membrane 5 is not particularly limited. For example, the electrolyte membrane 5 on which the fuel-side electrode 6 and the oxygen-side electrode 7 are formed may be pressed from both sides in the thickness direction of the electrolyte membrane 5. A hydraulic press, for example, may be used to press the electrolyte membrane 5. At this time, heating may be performed simultaneously with pressing (hot pressing). Hot pressing allows the fuel-side electrode 6 and the oxygen-side electrode 7 to be joined to the electrolyte membrane 5 at a lower pressure. Another example is joining the fuel-side electrode 6 formed on the fuel-side diffusion layer 8, the electrolyte membrane 5, and the oxygen-side electrode 7 formed on the oxygen-side diffusion layer 9, which are stacked in this order in a cell, using a fixture.

[0080] In this way, the membrane electrode assembly 2 is manufactured.

[0081] The fuel-side diffusion layer 8 supplies fuel to the fuel-side electrode 6, and also has functions such as collecting electrons generated by chemical reactions and protecting the electrolyte membrane 5. The fuel-side diffusion layer 8 is preferably made of a material that is gas permeable and electrically conductive, as well as durable and mechanically strong, such as carbon paper or carbon cloth, or gas-permeable materials containing carbon paper or carbon cloth that has been optionally fluorinated.

[0082] The fuel-side diffusion layer 8 is commercially available, and examples thereof include B-1 Carbon Cloth Type A No wet proofing (manufactured by BASF), ELAT (registered trademark: manufactured by BASF), and SIGRACET (registered trademark: manufactured by SGL).

[0083] The oxygen-side diffusion layer 9 supplies air (oxygen, water) to the oxygen-side electrode 7, and also has functions related to the collection of electrons generated by chemical reactions, protection of the electrolyte membrane 5, and discharge of water. Examples of the oxygen-side diffusion layer 9 include the gas-permeable materials exemplified for the fuel-side diffusion layer 8.

[0084] As described above, the fuel-side diffusion layer 8 and the oxygen-side diffusion layer 9 may have the fuel-side electrode 6 and the oxygen-side electrode 7 formed on their surfaces, respectively, and may function as electrodes, or may be provided separately from the fuel-side electrode 6 and the oxygen-side electrode 7 formed on the electrolyte membrane 5 and have a function related to protecting the electrodes.

[0085] When the fuel-side diffusion layer 8 and the oxygen-side diffusion layer 9 have a function of protecting the electrodes, the fuel-side diffusion layer 8 and the oxygen-side diffusion layer 9 may be arranged such that the fuel-side diffusion layer 8 is laminated on one side of the electrolyte membrane 5 so as to cover the fuel-side electrode 6, and the oxygen-side diffusion layer 9 is laminated on the other side of the electrolyte membrane 5 so as to cover the oxygen-side electrode 7.

[0086] At this time, there is no particular limitation on the means for laminating the fuel-side diffusion layer 8 and the oxygen-side diffusion layer 9 on the electrolyte membrane 5. For example, they may be fixed with a gasket or by applying external pressure (including hot pressing).

[0087] The fuel supply member 3 is made of a gas-impermeable conductive material and supplies liquid fuel to the fuel-side electrode 6. The fuel supply member 3 has grooves formed in a recessed shape, such as a zigzag groove, on its surface. The surface of the fuel supply member 3 on which the grooves are formed faces and contacts the fuel-side electrode 6. As a result, a fuel supply path 10 is formed between one surface of the fuel-side electrode 6 and the other surface of the fuel supply member 3 (the surface on which the grooves are formed) to bring the fuel components into contact with the entire fuel-side electrode 6.

[0088] The fuel supply path 10 has a fuel supply port 11 formed at one end (upper side of the paper in FIG. 1 ) for allowing fuel components to flow into the fuel supply member 3, and a fuel discharge port 12 formed at the other end (lower side of the paper in FIG. 1 ) for discharging the fuel components from the fuel supply member 3.

[0089] The air supply member 4 is made of a gas-impermeable conductive material and supplies air (oxygen, water) to the oxygen-side electrode 7. The air supply member 4 has grooves formed in a recessed shape, such as a zigzag groove, on its surface. The air supply member 4 may have the grooved surface facing and in contact with the oxygen-side electrode 7. As a result, an air supply path 13 is formed between the other surface of the oxygen-side electrode 7 and one surface of the air supply member 4 (the surface with the grooves) to bring air (oxygen, water) into contact with the entire oxygen-side electrode 7.

[0090] The air supply path 13 has an air supply port 14 formed at one end (upper side of the paper in FIG. 1 ) for allowing air (oxygen, water) to flow into the air supply member 4, and an air exhaust port 15 formed at the other end (lower side of the paper in FIG. 1 ) for exhausting the air (oxygen, water) from the air supply member 4.

[0091] An outline of the operation of the above-described electrochemical device 1 will now be described. In the electrochemical device 1, fuel components are supplied to the fuel-side electrode 6 from the fuel supply port 11. Meanwhile, air (oxygen, water) is supplied to the oxygen-side electrode 7 from the air supply port 14.

[0092] On the anode side, liquid fuel passes through the fuel supply path 10 while contacting the fuel-side electrode 6. On the other hand, on the cathode side, air (oxygen, water) passes through the air supply path 13 while contacting the oxygen-side electrode 7.

[0093] Then, an electrochemical reaction occurs at each electrode (fuel side electrode 6 and oxygen side electrode 7), generating an electromotive force.

[0094] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. (Example 1) As shown in FIG. 1 , a resin composition of the present invention was produced to obtain an anion exchange electrolyte membrane. The specific production method is described below. A 16 μm-thick PEEK membrane (manufactured by Victrex, crystallinity 11%) was immersed in a predetermined pretreatment solvent, tetraethylene glycol, at 50°C for 18 hours, air-dried in a draft for 3 hours, and then vacuum-dried at room temperature for 18 hours to obtain a pretreated PEEK film (pretreatment step). The pretreated PEEK film was irradiated with 160 kGy of gamma rays at room temperature in an argon atmosphere (radiation irradiation step), and then immersed in a chloromethylstyrene (CMS) / reaction solvent (CMS:reaction solvent = 1:1) in an 80°C thermostatic chamber for 72 hours to graft polymerize CMS onto the PEEK main chain, obtaining a resin composition with a graft ratio of 66% (graft polymerization step).

[0095] The resulting resin composition (graft membrane) was allowed to stand in a trimethylamine (TMA) aqueous solution (concentration: 30 wt%) for 24 hours to react (ionic compound introduction step). After the reaction, the membrane was washed five times with purified water and vacuum dried at room temperature to obtain an anion exchange membrane (resin composition) with chloride ions as counter anions, with an N-alkylation reaction yield of 83%. The resulting anion exchange membrane was immersed in a 1 M potassium hydroxide aqueous solution at room temperature for 18 hours to replace the counter anions with hydroxide ions. The membrane was then washed twice with deionized water from which residual carbon dioxide had been removed by nitrogen bubbling, and the immersion procedure for 30 minutes was repeated twice to obtain an anion exchange membrane with hydroxide ions as counter ions.

[0096] Example 2: The graft membrane obtained in Example 1 was immersed in an 18 wt % tetramethylimidazole (TMIm)-dioxane solution (dioxane:water = 50:50 vol%) at 60°C for 18 hours to perform quaternization (ionic compound introduction step). After the reaction, the membrane was washed five times with purified water and vacuum dried at room temperature to obtain an anion exchange membrane with chloride ions as counter anions, with an N-alkylation reaction yield of 83%. The resulting anion exchange membrane was immersed in a 1 M potassium hydroxide aqueous solution at room temperature for 18 hours to replace the counter anions with hydroxide ions. The membrane was then washed twice with deionized water from which residual carbon dioxide had been removed by nitrogen bubbling, and the immersion for 30 minutes was repeated twice to obtain an anion exchange membrane with hydroxide ions as counter ions.

[0097] Example 3: A 16 μm thick PEEK film (manufactured by Victrex, crystallinity 11%) was immersed in dioxane solvent at 50° C. for 18 hours, air-dried in a draft for 3 hours, and then vacuum-dried at room temperature for 18 hours to obtain a pretreated PEEK film. The pretreated PEEK film was irradiated with 160 kGy of gamma rays at room temperature in an argon atmosphere, and then immersed in chloromethylstyrene (CMS) / dioxane (CMS:dioxane = 1:1) in a thermostatic chamber at 90° C. for 96 hours to graft polymerize CMS onto the PEEK main chain, yielding a resin composition with a graft ratio of 35%.

[0098] Comparative Example 1 A 16 μm thick PEEK membrane (manufactured by Victrex, crystallinity 11%) that had not been subjected to solvent immersion treatment was irradiated with 160 kGy of gamma rays at room temperature in an argon atmosphere, and then immersed in chloromethylstyrene (CMS) / dioxane (CMS:dioxane=1:1) in a thermostatic bath at 90° C. for 96 hours to graft polymerize CMS onto the PEEK main chain (graft ratio 24%).

[0099] Comparative Example 2: A 25 μm-thick ETFE membrane (manufactured by DuPont) was irradiated with 50 kGy of gamma rays under an argon atmosphere at room temperature, and then immersed in a chloromethylstyrene (CMS) / xylene solution (CMS:xylene = 1:1) for 2 hours in a 60 °C thermostatic chamber to graft polymerize CMS onto the ETFE main chain (graft rate 76%). The resulting resin composition (graft membrane) was immersed in a trimethylamine aqueous solution (concentration 30 wt%) and reacted at room temperature for 16 hours. After washing with deionized water, the membrane was immersed in 1 M hydrochloric acid for 24 hours, and then immersed in deionized water and washed for 2 hours to obtain an anion exchange membrane with chloride ions as counterions with a 100% quaternization reaction yield. The resulting anion exchange membrane was converted into an anion exchange membrane with hydroxide ions as counterions by the same procedure as in Example 1.

[0100] The anion exchange membranes obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were measured for grafting rate, ion exchange capacity, water content, electrical conductivity, and breaking strength. The results are summarized in Table 1.

[0101] Each measurement value was determined as follows: (1) Graft ratio (%) When the polymer base material is the main chain portion and the portion grafted with the starting material is the graft chain portion, the weight ratio of the graft chain portion to the main chain portion is calculated by the following formula: graft ratio (X ｄｇ The weight percent is expressed as a percentage by weight.

[0102] X ｄｇ = 100(W ２ -W １ ) / W １ W １ W: Weight in dry state before grafting (g) ２ : dry weight after grafting (g)

[0103] (2) Ion Exchange Capacity (mmol / g) The ion exchange capacity (IEC) of an anion exchange electrolyte membrane is expressed by the following formula:

[0104] IEC = [n (basic group) ｏｂｓ ] / W ３ (mM / g) [n (basic group) ｏｂｓ]: Amount of basic groups in the anion exchange membrane (mM) W ３ : Dry weight (g) of anion exchange membrane

[0105] [n (basic group) ｏｂｓ The measurement of the basic group concentration of the anion exchange electrolyte membrane is carried out as follows: an anion exchange electrolyte membrane in the hydroxide (hereinafter referred to as "OH type") state is immersed in an accurately measured volume of 0.1 M hydrochloric acid solution at room temperature for 12 hours to completely convert it into a chloride (hereinafter referred to as "Cl type") state, and then the concentration of the remaining hydrochloric acid solution is back-titrated with 0.1 M NaOH to determine the basic group concentration of the anion exchange electrolyte membrane.

[0106] (3) Water content (%) A Cl-type or OH-type anion exchange electrolyte membrane stored in water at room temperature was taken out, the water on the surface was lightly wiped off, and the weight was measured (W ５ (g)). This membrane was vacuum dried at 40° C. for 16 hours, and then weighed to determine the dry weight W of the anion exchange membrane. ４ (g) is found, and W ５ , W ４ The moisture content is calculated using the following formula:

[0107] Moisture content = 100 (W ５ -W ４ ) / W ４

[0108] (4) Electrical Conductivity (S / cm) For measurement by an AC method, a membrane resistance measurement cell consisting of platinum electrodes and a HIOKI LCR meter 3522 were used. An anion exchange electrolyte membrane in a saturated swollen state in water at room temperature was taken out, sandwiched between platinum electrodes, and immersed in deionized water at 60°C for 2 minutes, after which the membrane resistance (Rm) was measured based on impedance. The electrical conductivity (standard) of the anion exchange electrolyte membrane was calculated using the following formula.

[0109] κ = 1 / Rm·d / S κ: electrical conductivity of the anion exchange membrane (S / cm) d: thickness of the anion exchange membrane (cm) S: current-carrying area of ​​the anion exchange membrane (cm ２ )

[0110] The electrical conductivity of the resin composition (anion exchange electrolyte membrane) according to an embodiment of the present invention is usually 40 mS / cm or more, and preferably 50 mS / cm or more. When the electrical conductivity of the resin composition is in this range, the resin composition can be sufficiently practical, particularly as an anion exchange electrolyte membrane.

[0111] (5) Breaking Strength The graft membrane prepared as above was preliminarily cut into a dumbbell shape (ASTM D-1822-L), and then subjected to a tensile test at 10 mm / min using a tensile tester (Shimazu EZ-L200N, 1 N load cell) to measure the breaking strength.

[0112]

[0113] <Durability (Breaking Strength, Shape Observation)> The graft membrane prepared as described above was pre-cut into a dumbbell shape (ASTM D-1822-L) and then immersed in a 1 M KOH aqueous solution. After a predetermined time, the membrane was removed and subjected to a tensile test at 10 mm / min using a tensile tester (Shimazu EZ-L200N, 1 N load cell) to measure the breaking strength. Furthermore, the ETFE-g-CMS / TMA membrane and the PEEK-g-CMS / TMA membrane, which had been hydroxylated by pre-immersion in a 1 M KOH aqueous solution, were subjected to shape observation using samples immersed for a predetermined time. These results are shown in Figure 3. Figure 3(A) is a graph showing the results of a tensile test after immersion in 1 M KOH at 80°C. Figure 3(B) shows the change in membrane shape before and after an alkali resistance test.

[0114] The PEEK-g-CMS / TMA membrane obtained in Example 1 and the ETFE-g-CMS / TMA membrane obtained in Comparative Example 2 were subjected to an alkali resistance test in a 1M KOH aqueous solution at 80°C. The ETFE-g-CMS / TMA membrane subjected to quaternization with TMA followed by hydroxylation treatment in a 1M KOH aqueous solution had a breaking strength of 23 MPa, while the PEEK-g-CMS / TMA membrane (graft ratio 66%) subjected to hydroxylation treatment had a breaking strength of 75 MPa, three times stronger. The PEEK-based anion exchange electrolyte membrane exhibited both high electrical conductivity and mechanical properties (Figure 3(A)). The change in membrane strength after the alkali resistance test was also examined. The breaking strength of the ETFE-g-CMS / TMA membrane decreased with immersion time, reaching 9 MPa after 24 hours of immersion. On the other hand, the breaking strength of the PEEK-g-CMS / TMA film was 61 MPa after 24 hours of immersion, a decrease of only 13% (FIG. 3(A)).

[0115] After the alkali resistance test, the shape of the electrolyte membrane was observed (Figure 3(B)). The shape of the PEEK-g-CMS / TMA membrane remained unchanged before and after the test. On the other hand, the ETFE-g-CMS / TMA membrane became embrittled and partially torn, making it difficult to handle for conductivity measurement.

[0116] [Electrochemical Device] As working examples and comparative examples of electrochemical devices according to the present invention, membrane electrode assemblies and fuel cells were manufactured. (Working Example 1) [1] Preparation of catalyst ink for fuel-side electrode A paste prepared by dispersing a platinum-ruthenium-carbon catalyst (ruthenium content: 30 wt %, platinum content: 23 wt %) and carbon black (VULCAN (registered trademark) XC-72R) in distilled water was mixed with the resin composition of Example 1 dispersed in isopropanol so that the platinum:carbon:binder ratio was 1.00:2.50:1.04, and the mixture was then ultrasonically dispersed at 10°C for 60 minutes to prepare a catalyst ink for the fuel-side electrode.

[0117] [2] Preparation of catalytic ink for oxygen-side electrode A paste prepared by dispersing a platinum-carbon catalyst (platinum content 46 wt%) and carbon black (VULCAN (registered trademark) XC-72R) in distilled water and the resin composition of Example 1 dispersed in isopropanol were mixed so that the platinum:carbon:binder ratio was 1.00:1.20:0.55, and the mixture was dispersed using ultrasonic waves at 10°C for 60 minutes to prepare catalytic ink for the oxygen-side electrode.

[0118] [3] Application and drying of each catalyst ink The catalyst ink for the fuel side electrode and the oxygen side electrode was applied to a gas diffusion layer (SIGRACET (registered trademark) 25BC) by spraying. After that, it was dried at 25°C to form a catalyst ink with a surface area of ​​5 cm. ２ , a fuel electrode with a thickness of 150 μm, and a catalyst area of ​​5 cm ２ The gas diffusion layers correspond to the fuel-side diffusion layer 8 and the oxygen-side diffusion layer 9 described above, and the fuel-side electrode and the oxygen-side electrode in this example were formed on the fuel-side diffusion layer 8 and the oxygen-side diffusion layer 9, respectively, and were integrated.

[0119] [4] Bonding of the fuel-side electrode and oxygen-side electrode to the electrolyte membrane (preparation of membrane electrode assembly) The prepared fuel-side electrode and oxygen-side electrode, and the resin composition of Example 1 (anion exchange electrolyte membrane) were each immersed in a 1 M KOH aqueous solution in separate containers for 1 hour, and after wiping off excess KOH aqueous solution from the surfaces, the fuel-side electrode, electrolyte membrane (anion exchange electrolyte membrane), and oxygen-side electrode were stacked on the fuel cell in this order, and the assembly bolts of the fuel cell were tightened with a torque of 8 Nm to join them.

[0120] [5] Production of Fuel Cell A fuel cell having a single cell unit structure shown in FIG. 1 was formed by providing a fuel supply member and an air supply member to the obtained membrane electrode assembly.

[0121] Comparative Manufacturing Example A membrane electrode assembly and a fuel cell were obtained in the same manner as in the working manufacturing example, except that the resin composition of Comparative Example 1 was mixed in place of the resin composition of Example 1 in preparing the catalyst ink for the fuel-side electrode and the catalyst ink for the oxygen-side electrode.

[0122] The fuel cells of the single cell units obtained in the Working Example and the Comparative Example were used to evaluate output and durability. (Fuel Cell Output Test) An output test was conducted using the fuel cells of the single cell units obtained in the Working Example and the Comparative Example. The fuel cell temperature was set to 80°C, and in the Working Example, hydrogen gas was supplied to the anode side at 70°C at 500 ml / min, and oxygen at 71°C was supplied to the cathode side at 500 ml / min to generate electricity. On the other hand, in the Comparative Example, hydrogen gas was supplied to the anode side at 78°C at 500 ml / min, and oxygen at 79°C was supplied to the cathode side at 500 ml / min to generate electricity. The current density was set to 0 mA / cm. ２ The voltage was measured as the current was gradually increased from 0.01 V, and the output power density at each current value was calculated from the obtained values.

[0123] 4 is a diagram showing the measurement results obtained in the output test. In the figure, the plots shown in white indicate a graph of current density vs. output density, and the plots shown in black indicate a graph of current density vs. cell voltage. As shown in FIG. 4, in the fuel cell of the comparative manufacturing example using the binder for forming the electrode catalyst layer of the membrane electrode assembly of Comparative Example 1, the maximum output power density was 90 mW / cm ２ In contrast, in the fuel cell of the working example using the binder for forming the electrode catalyst layer of the membrane electrode assembly of Example 1, the maximum output power density was 488 mW / cm ２ Therefore, it can be seen that the power generation performance of the fuel cell of the Working Production Example, which used the binder for forming an electrode catalyst layer of the membrane electrode assembly of Example 1, is improved compared to the power generation performance of the fuel cell of the Comparative Production Example, which used the binder for forming an electrode catalyst layer of the membrane electrode assembly of Comparative Example 1.

[0124] The above-described embodiments are examples of the resin composition, the method for producing the resin composition, and the electrochemical device. The resin composition, the method for producing the resin composition, and the electrochemical device according to the present invention are not limited to the above-described embodiments, and the resin composition, the method for producing the resin composition, and the electrochemical device according to the above-described embodiments may be modified within the scope of the claims.

[0125] In the above-described embodiment, the resin composition and the method for producing the resin composition of the present invention are mainly used as materials for electrolyte layers (electrolyte membranes) and electrodes (binders for forming electrode catalyst layers) in electrochemical devices, and the method for producing the same. However, the present invention is not limited thereto. For example, the resin composition and the method for producing the resin composition of the present invention can be used as materials and the method for producing the same in various fields, taking advantage of the high ionic conductivity and alkali resistance. For example, the resin composition of the present invention may be used for ion exchange membranes, reverse osmosis membranes, etc.

[0126] In the above-described embodiments, the electrochemical device of the present invention has been described mainly as a fuel cell, but is not limited thereto. For example, the electrochemical device of the present invention may be any device that uses a resin composition with high ionic conductivity and alkali resistance as an electrolyte layer (electrolyte membrane) and electrode material (including a catalyst and a binder for an active material), and may also be applied to other electrochemical devices such as metal-air batteries and electrolytic cells. In a metal-air battery, the fuel-side electrode 6 in the electrochemical device shown in the embodiment is replaced with an active material such as zinc, aluminum, magnesium, or lithium.

[0127] [Results of Additional Tests] In the additional tests described below, anion exchange electrolyte membranes obtained by the above-described method for producing a resin composition were used to evaluate alkali resistance.

[0128] (Accelerated Test for Alkali Resistance) A PEEK-g-CMS / TMA membrane (grafting rate 72%, IEC 1.93 mmol / g water content 62%) obtained in accordance with the method of Example 1 and an ETFE-g-CMS / TMA membrane (grafting rate 86.3%, IEC 2.4 mmol / g, water content 166%) obtained in accordance with the method of Comparative Example 2 were each immersed in a 7 M KOH aqueous solution at 60°C, and an accelerated test for the alkali resistance of the anion exchange electrolyte membrane was performed based on the change in conductivity with time.

[0129] The sample was immersed in a 7 M KOH aqueous solution at 60°C for a predetermined time, removed, and washed by shaking for 6 hours in purified water that had been decarbonized by nitrogen bubbling. Then, impedance was measured in the nitrogen-bubbled water at 60°C, and the electrical conductivity was calculated from the measured resistance value.

[0130] FIG. 5 is a diagram showing the results obtained in an accelerated test of the alkali resistance of an anion exchange electrolyte membrane.

[0131] As shown in Fig. 5, the conductivity of the ETFE electrolyte membrane rapidly decreased after 17 hours of immersion, reaching 32% of the initial value after 17 hours. On the other hand, the conductivity of the PEEK electrolyte membrane reached 150 mS / cm after 1000 hours, maintaining 85% or more of its performance.

[0132] Therefore, it is clear that the PEEK-g-CMS / TMA membrane suppresses deterioration of alkali resistance compared to the ETFE-g-CMS / TMA membrane.

[0133] (Summary) As a result of intensive research into the above-mentioned problems, the present inventors have found that an anion exchange electrolyte membrane having excellent alkali resistance at high temperatures and gas barrier properties can be obtained by providing a resin composition that uses an aromatic hydrocarbon-based polymer as a base material and that includes graft polymer chains having cationic functional groups on the base material, and have thus completed the present invention. That is, the present invention relates to the following resin composition, a method for producing a resin composition, and an electrochemical device.

[0134] A resin composition according to a first aspect of the present invention for solving the above-mentioned problems is a resin composition having an aromatic hydrocarbon-based polymer as a base material and having graft polymer chains on the base material, wherein the graft polymer chains have cationic functional groups.

[0135] This resin composition comprises a base material of an aromatic hydrocarbon-based polymer that has excellent alkali resistance at high temperatures and gas barrier properties, and a graft polymer chain having a cationic functional group, and therefore can provide an anion exchange electrolyte membrane that has excellent alkali resistance at high temperatures and gas barrier properties.

[0136] Furthermore, the resin composition according to the second aspect of the present invention is characterized in that, in the first aspect, the breaking strength after immersion in a 1 M potassium hydroxide aqueous solution at 80°C for 5 hours is 40 MPa or more.

[0137] This feature makes it possible to provide an anion exchange electrolyte membrane that is particularly excellent in alkali resistance at high temperatures.

[0138] Furthermore, the resin composition according to a third aspect of the present invention is characterized in that, in the first or second aspect, the graft ratio of the graft polymer chains to the substrate is 30% or more.

[0139] According to this feature, since many graft polymerization chains can be introduced into an aromatic hydrocarbon-based polymer that has chemical resistance and into which it is difficult to introduce other monomers by graft polymerization or the like, it is possible to provide an anion exchange electrolyte membrane with high conductivity.

[0140] A fourth aspect of the present invention for solving the above-mentioned problems provides a method for producing a resin composition using an aromatic hydrocarbon-based polymer as a base material, the method comprising: a pretreatment step of immersing the base material in a solvent; a radiation irradiation step of irradiating the pretreated base material obtained by the pretreatment step with radiation; and a graft polymerization step of graft polymerizing a vinyl monomer onto the base material irradiated by the radiation irradiation step.

[0141] According to this method for producing a resin composition, a lamellar structure is formed in the aromatic hydrocarbon polymer substrate by immersion treatment using a solvent, which has the effect of improving the graft rate of the aromatic hydrocarbon polymer to the substrate.

[0142] Furthermore, the method for producing a resin composition according to a fifth aspect of the present invention is characterized in that, in the fourth aspect, it further comprises an ionic compound introduction step of introducing a compound having an ionic functional group into the graft polymer chain formed by the vinyl monomer.

[0143] According to this feature, the compound having an ionic functional group is introduced into the graft polymerization chain of the vinyl monomer, and therefore the ionic functional group can be introduced more easily than by directly graft polymerizing the compound having the ionic functional group onto the base material of the hydrophobic aromatic hydrocarbon polymer.

[0144] A sixth aspect of the present invention is a method for producing a resin composition according to the fourth or fifth aspect, characterized in that the solvent is a long-chain ether or an alcohol thereof.

[0145] According to this feature, the immersion treatment is carried out using a long-chain ether or its alcohol as a solvent, which has the effect of improving the grafting rate of the aromatic hydrocarbon polymer to the substrate.

[0146] Furthermore, the method for producing a resin composition according to a seventh aspect of the present invention is characterized in that, in any one of the fourth to sixth aspects, the aromatic hydrocarbon polymer is polyether ether ketone.

[0147] According to this feature, the effect of excellent alkali resistance at high temperatures is further exhibited, and an anion exchange electrolyte membrane with even greater durability can be provided.

[0148] In order to solve the above problems, an electrochemical device according to an eighth aspect of the present invention is an electrochemical device comprising an electrolyte layer and two electrodes arranged opposite each other with the electrolyte layer sandwiched therebetween, characterized in that the electrolyte layer and / or the electrodes comprise the resin composition according to any one of the first to third aspects.

[0149] According to this electrochemical device, since the electrolyte layer and electrodes contain the resin composition of the present invention, the device is provided with an anion exchange electrolyte membrane that is excellent in alkali resistance and gas barrier property at high temperatures, an electrolyte membrane with high conductivity, and electrodes, and therefore an electrochemical device with excellent durability and electrical properties can be provided.

[0150] An electrochemical device according to a ninth aspect of the present invention is characterized in that it is a fuel cell, a metal-air battery, or a water electrolysis apparatus.

[0151] According to this feature, since the electrolyte layer or electrode contains the resin composition of the present invention, a high-power fuel cell, metal-air battery, or water electrolysis device can be provided.

[0152] The resin composition and the method for producing the resin composition of the present invention are used as a resin composition imparted with functions related to ion conductivity and alkali resistance, and as a method for producing the same. Furthermore, the electrochemical device of the present invention is used as an electrochemical device including an electrolyte layer and electrodes. It is particularly suitable for use as a fuel cell, a metal-air battery, a hydrogen pump, or a water electrolysis device.

[0153] REFERENCE SIGNS LIST 1 electrochemical device, 2 membrane electrode assembly, 3 fuel supply member, 4 air supply member, 5 electrolyte membrane (electrolyte layer), 6 fuel side electrode, 7 oxygen side electrode, 8 fuel side diffusion layer, 9 oxygen side diffusion layer, 10 fuel supply channel, 11 fuel supply port, 12 fuel outlet, 13 air supply channel, 14 air supply port, 15 air outlet

Claims

1. A resin composition having an aromatic hydrocarbon polymer as a base material and a graft polymer chain on the base material, characterized in that the graft polymer chain has a cationic functional group.

2. The resin composition according to claim 1, characterized in that the breaking strength after immersion in a 1M aqueous potassium hydroxide solution at 80°C for 5 hours is 40 MPa or more.

3. The resin composition according to claim 1 or 2, wherein the graft ratio of the graft polymer chains to the base material is 30% or more.

4. A method for producing a resin composition using an aromatic hydrocarbon polymer as a base material, comprising: a pretreatment step of immersing the base material in a solvent; a radiation exposure step of irradiating the pretreated base material obtained by the pretreatment step with radiation; and a graft polymerization step of graft polymerizing a vinyl monomer onto the base material irradiated by the radiation exposure step.

5. A method for producing a resin composition according to claim 4, further comprising: a step of introducing an ionic compound into the graft polymer chain formed by the vinyl monomer, the compound having an ionic functional group.

6. A method for producing a resin composition according to claim 4 or 5, characterized in that the solvent is a long-chain ether or an alcohol thereof.

7. A method for producing a resin composition according to any one of claims 4 to 6, characterized in that the aromatic hydrocarbon polymer is polyether ether ketone.

8. An electrochemical device comprising an electrolyte layer and two electrodes disposed opposite each other with the electrolyte layer interposed therebetween, characterized in that the electrolyte layer and / or the electrodes comprise the resin composition according to any one of claims 1 to 3.

9. The electrochemical device according to claim 8, which is a fuel cell, a metal-air battery or a water electrolysis device.

Images