JP2014044940A - Ion conductivity-imparting agent, anode catalyst layer, membrane-electrode assembly formed using the catalyst layer, anion exchange membrane fuel cell, and method of operating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion conductivity imparting-agent for an anode catalyst layer of an anion exchange membrane fuel cell, good in conformability of a hydrocarbon-based anion exchange membrane and an anode catalyst layer at a junction interface therebetween, and high in initial performance, and further to provide an ion conductivity-imparting agent hardly deteriorated in performance even after long-term use.SOLUTION: In an ion conductivity-imparting agent for use in forming an anode catalyst layer of an anion exchange membrane fuel cell, an ion conductivity-imparting agent comprising a hydrocarbon-based anion exchange resin having an anion exchange capacity of 1.8-3.5 mmol/g is used.

Description

  The present invention relates to an ion conductivity-imparting agent used for forming an anode catalyst layer of an anion-exchange membrane fuel cell among solid polymer fuel cells, an anode catalyst layer formed using the ion-conductivity imparting agent, The present invention relates to a membrane-electrode assembly formed using the anode catalyst layer (hereinafter, the membrane-electrode assembly is also referred to as “MEA”), an anion exchange membrane fuel cell including the MEA, and an operation method thereof.

  A polymer electrolyte fuel cell is a fuel cell that uses a solid polymer such as an ion exchange resin as an electrolyte, and has a feature that its operating temperature is relatively low. As the electrolyte of the polymer electrolyte fuel cell, a cation exchange membrane or an anion exchange membrane can be used. Regardless of which electrolyte is used, the polymer electrolyte fuel cell has the following basic structure.

  FIG. 1 is a conceptual diagram showing a basic structure of a polymer electrolyte fuel cell. In FIG. 1, reference numerals 1a and 1b denote battery partition walls, in which a fuel circulation hole 2 communicating with the outside is formed in the battery partition wall 1a, and an oxidant gas circulation hole 3 communicating with the outside is formed in the battery partition wall 1b. The spaces in the battery partition walls 1 a and 1 b are divided into two by the solid polymer electrolyte membrane 6. A fuel chamber side gas diffusion electrode (anode) 4 is bonded to one surface of the solid polymer electrolyte membrane 6, and an oxidant chamber side gas diffusion electrode (cathode) 5 is bonded to the other surface (back surface). . A fuel chamber (anode chamber) 7 formed by being surrounded by the battery partition wall 1a and the solid polymer electrolyte membrane 6 is communicated with the outside by the fuel flow hole 2, and the battery partition wall 1b and the solid polymer electrolyte membrane 6 are connected to each other. The oxidant chamber (cathode chamber) 8 formed by being surrounded by is communicated with the outside by the oxidant gas flow hole 3.

  The polymer electrolyte fuel cell having such a basic structure supplies a fuel made of hydrogen gas, methanol, or the like to the fuel chamber 7 through the fuel circulation hole 2, and oxygen or Electric energy is generated by the following mechanism by supplying an oxidant gas composed of an oxygen-containing gas such as air and connecting an external load circuit between the two gas diffusion electrodes. That is, when a cation exchange membrane is used as the solid polymer electrolyte membrane, protons (hydrogen ions) generated by contact of the catalyst and fuel contained in the electrode at the anode 4 are converted into solid polymer electrolyte. It conducts through the membrane 6 and moves to the oxidant chamber 8, and reacts with oxygen in the oxidant gas at the cathode 5 to generate water. On the other hand, the electrons generated simultaneously with the protons in the anode 4 move to the cathode 5 through the external load circuit, so that the energy of the reaction can be used as electric energy.

  In the polymer electrolyte fuel cell having the above structure, a perfluorocarbon sulfonic acid resin membrane is most commonly used as the polymer electrolyte membrane. In addition, as a gas diffusion electrode using such a perfluorocarbon sulfonic acid resin film, a gas in which a catalyst made of metal particles such as platinum supported on a conductive agent such as carbon black is supported by an electrode substrate made of a porous material. A diffusion electrode or a gas diffusion electrode in which the catalyst is formed in layers on a perfluorocarbon sulfonic acid resin film is generally used. Usually, the gas diffusion electrode is bonded to the perfluorocarbon sulfonic acid resin film by thermocompression bonding to the perfluorocarbon sulfonic acid resin film. And when joining by such a method, in order to raise the utilization factor of the proton which generate | occur | produces on the catalyst inside a gas diffusion electrode (in other words, for the purpose of moving this proton efficiently to an electrode) A perfluorocarbon sulfonic acid resin solution is applied to the bonding surface of the diffusion electrode as an ion conductivity imparting agent, or a perfluorocarbon sulfonic acid resin is blended inside the gas diffusion electrode (Patent Documents 1 and 2). ). The perfluorocarbon sulfonic acid resin also has a function of improving the bondability between the solid polymer electrolyte membrane and the gas diffusion electrode.

  However, in the polymer electrolyte fuel cell using such a perfluorocarbon sulfonic acid resin membrane, the following problems are mainly caused by the perfluorocarbon sulfonic acid resin membrane. (I) Since the reaction field is an acidic atmosphere, it is necessary to use an expensive noble metal catalyst such as platinum. (Ii) Since hydrofluoric acid is generated by incineration, environmental compatibility is poor. (Iii) Since the permeability of fuel gas and oxidant gas is relatively high, voltage loss occurs. (Iv) Since the raw material is expensive, it is difficult to reduce the cost.

  In order to solve these problems, particularly the above problem (i), several polymer electrolyte fuel cells using hydrocarbon-based anion exchange membranes instead of perfluorocarbon sulfonic acid resin membranes have been proposed (patents). Literature 3-5).

  These polymer electrolyte fuel cells using a hydrocarbon-based anion exchange membrane can generate power using a fuel gas such as hydrogen and an oxidant gas such as oxygen, as in the case of using a perfluorocarbon sulfonic acid membrane. The reaction mechanism in the electrode and the ion species conducted in the solid polymer electrolyte 6 are different.

  For example, a fuel containing hydrogen is supplied to the anode chamber 7 through the fuel circulation hole 2, and an oxidant gas containing oxygen such as oxygen or air is supplied to the cathode chamber 8 through the oxidant gas circulation hole 3. When an external load circuit is connected between the cathodes 5, hydroxide ions are generated at the cathode 5 when the catalyst contained in the electrodes comes into contact with oxygen in the oxidant gas and water. That is, water is essential for the electrode reaction at the cathode. Next, the hydroxide ions generated here are conducted through the solid polymer electrolyte membrane 6 and moved to the anode side, and react with the fuel at the anode 4 to generate water. Electrons generated simultaneously with water in the anode 4 move to the cathode 5 through the external load circuit, and thus the energy of the reaction can be used as electric energy.

  A polymer electrolyte fuel cell using a hydrocarbon-based anion exchange membrane has a basic reaction atmosphere, so a polymer electrolyte fuel cell using a cation exchange membrane such as a perfluorocarbon sulfonic acid resin membrane Has the following advantages.

(I) Since a catalyst made of a transition metal with abundant reserves can be used, the options for the catalyst are widened.
(Ii) The amount of usable fuel increases, for example, basic fuel can be used.
(Iii) A metal battery partition excellent in processability and mass productivity can be used without being subjected to acid resistance treatment.
(Iv) It is advantageous for oxygen reduction reaction.

  In the gas diffusion electrode of the polymer electrolyte fuel cell disclosed in each of the above publications, when a perfluorocarbon sulfonic acid resin membrane is used, an ion conductivity imparting agent made of perfluorocarbon sulfonic acid resin is added to the gas diffusion electrode. For the same reason as the addition, various anion exchange resins are added as an ion conductivity imparting agent. As such an anion exchange resin, for example, a fluororesin-based resin such as a polymer obtained by treating a terminal of a perfluorocarbon polymer having a sulfonic acid group with a diamine to be quaternized is known (for example, Patent Document 6). When this is used, when the solid polymer electrolyte membrane is the hydrocarbon-based anion exchange membrane, the familiarity at the bonding interface between the hydrocarbon-based ion exchange membrane and the gas diffusion electrode is deteriorated, and the bonding strength is reduced. Occurs.

  Therefore, when a hydrocarbon-based anion exchange membrane is used, the anion exchange resin as the ion conductivity-imparting agent is preferably a hydrocarbon-based one, and the block copolymer weight of the aromatic vinyl compound and the conjugated diene. An anion exchange resin in which an anion exchange group is introduced into a thermoplastic elastomer such as a coalescence has been proposed (Patent Document 7). In Patent Document 6, the hydrocarbon-based anion exchange resin is excellent in bondability with the above-described hydrocarbon-based ion exchange membrane, and is flexible and non-crosslinkable. Therefore, it is described that 0.5 to 1.5 mmol / g is good. In addition, from this, in the examples, such anion exchange resins are added to the cathode catalyst layer and those added to the anode catalyst layer are all non-crosslinkable, and their anion exchange capacity is used. Has a lower value of 0.8 to 1.3 mmol / g, and its water solubility (20 ° C.) is suppressed to a minimum value of 0.02 to 0.04 mass%.

  In a polymer electrolyte fuel cell using such a hydrocarbon-based anion exchange membrane and an ion conductivity-imparting agent, the ionic conductivity of the hydrocarbon-based anion exchange membrane and the ion conductivity-imparting agent is wet. It is demonstrated when it is in a state. Therefore, moisture is required to maintain the ionic conductivity of the hydrocarbon-based anion exchange membrane and the ionic conductivity-imparting agent. Further, as described above, water is consumed in the electrode reaction on the cathode side. Therefore, moisture needs to be continuously supplied into the fuel cell. In order to supply moisture into the fuel cell, a moisture supply device such as a humidifier is generally installed outside. However, the installation of the water supply device causes problems such as an increase in the size of the system, high price, and the necessity of precisely managing the water supply amount of the water supply device. Therefore, there is a need for a technique for configuring a fuel cell that can be operated under as low a humidification condition as possible, and ideally a fuel cell that can be operated only with moisture contained in the air without providing a moisture supply device.

JP-A-3-208260 JP-A-4-329264 Japanese Patent Laid-Open No. 11-273695 JP-A-11-135137 JP 2000-331693 A JP 2000-331693 A JP 2002-367626 A

  The present inventors examined a solid polymer fuel cell using a hydrocarbon-based anion exchange membrane as a solid polymer electrolyte membrane (hereinafter also referred to as “anion exchange membrane fuel cell”). As a result, when the moisture supply device is not installed, particularly when the humidity of the fuel gas supplied to the anode side is low, the performance of the anion exchange membrane type fuel cell is the ion conductivity imparting agent contained in the MEA, particularly the anode side. It was found that an anion exchange membrane fuel cell with sufficient performance could not be obtained depending on the properties of the ion conductivity-imparting agent contained therein. That is, as described above, in the conventional polymer electrolyte fuel cell using a hydrocarbon-based anion exchange membrane, the anion conduction of the hydrocarbon-based anion exchange resin blended in the anode catalyst layer as an ion conductivity imparting agent. Only the nature imparting agent having a small anion exchange capacity of 0.5 to 1.5 mmol / g is specifically known.

  As described above, water is generated by the electrode reaction on the anode side of the anion exchange membrane fuel cell, but a part of the water thus generated is dissipated in the fuel gas such as hydrogen. Only a part is held in the catalyst layer on the anode side (hereinafter also referred to as “anode catalyst layer”), and only a part thereof is supplied to the cathode side through the anion exchange membrane and consumed in the electrode reaction at the cathode. The Rukoto. The amount of water dissipated into the fuel gas is such that the lower the anion exchange capacity of the ion conductivity-imparting agent constituting the anode catalyst layer as described above, and the lower the humidity of the fuel gas supplied to the anode is, Become more. Accordingly, even when the anode is formed using an ion conductivity-imparting agent having a low anion exchange capacity as described above, even when it is on the anode side where water is generated, when the fuel gas supplied to the anode is operated at low humidity, There was a risk that sufficient moisture could not be retained in the anode catalyst layer. As a result, not only the ionic conductivity in the anode catalyst layer is insufficient, but also the water consumed by the cathode electrode reaction cannot be quickly supplied from the anode side to the catalyst active point, and the battery output is reduced. There was a thing. Furthermore, when the operation using the low-humidity fuel gas is continued for a long time, the water serving as the reaction substrate supplied from the anode side to the cathode side is insufficient, and the stability of the battery output is lowered. Furthermore, such a decrease in stability was significant when the air supplied to the cathode side was also low humidified.

  Therefore, the present invention is an ion conductivity-imparting agent for the anode catalyst layer of an anion exchange membrane fuel cell, and the familiarity of both at the joining interface between the hydrocarbon-based anion exchange membrane and the catalyst layer is good. An ion conductivity-imparting agent that provides high battery output even when the fuel gas supplied to the side has low humidity, and that stably provides high battery output even if the operation using low-humidity fuel gas is continued for a long time. The purpose is to provide.

  The inventors of the present invention have made extensive studies in order to solve the above-described problems. As a result, when the anode catalyst layer of MEA constituting the anion exchange membrane fuel cell is formed (hydrocarbon-based anion exchange membrane, anode catalyst layer, The present invention has been completed by finding that the above-mentioned problems can be solved by using a predetermined ion conductivity-imparting agent.

  That is, the first aspect of the present invention is an ion conductivity imparting agent used for forming an anode catalyst layer of an anion exchange membrane fuel cell, and a hydrocarbon having an anion exchange capacity of 1.8 to 3.5 mmol / g. It is an ion conductivity-imparting agent comprising a system anion exchange resin. The first invention includes an ion conductivity imparting agent in which the hydrocarbon-based anion exchange resin is in a non-crosslinked form. The first invention includes an ion conductivity-imparting agent in which the Young's modulus of the non-crosslinked hydrocarbon-based anion exchange resin is 1 to 300 MPa.

  The second aspect of the present invention is an anode catalyst layer for an anion exchange membrane fuel cell, comprising an anode catalyst and the ion conductivity-imparting agent.

The third aspect of the present invention is an MEA for an anion exchange membrane fuel cell comprising a structure comprising a hydrocarbon-based anion exchange membrane and the anode catalyst layer formed on one surface of the anion exchange membrane. It is. The third aspect of the present invention includes the case where the hydrocarbon-based anion exchange membrane is a hydrocarbon-based anion exchange membrane having a water permeability of 1400 g · m ⁻² · hr ⁻¹ or more at 25 ° C.

  A fourth present invention is an anion exchange membrane fuel cell comprising the MEA. The fourth present invention includes an anion exchange membrane fuel cell in which the cathode catalyst layer contains the cathode catalyst and the ion conductivity-imparting agent of the present invention.

  According to a fifth aspect of the present invention, there is provided an operating method for an anion exchange membrane fuel cell, wherein hydrogen is supplied to the anode chamber of the anion exchange membrane fuel cell and air is supplied to the cathode chamber to generate electric power. It is. In the fifth aspect of the present invention, when the hydrogen supplied to the anode chamber is hydrogen having a relative humidity of 40% or less at the operating temperature of the anion exchange membrane fuel cell, or further, the air supplied to the cathode chamber is This includes the case where the relative humidity at the operating temperature of the anion exchange membrane fuel cell is 70% or less, that is, the case where a moisture supply device such as a humidifier is not provided in the anion exchange membrane fuel cell.

  The MEA constructed using the ion conductivity-imparting agent of the present invention comprises an anode catalyst layer containing catalyst particles bonded to one surface of a hydrocarbon-based anion exchange membrane, and the MEA comprises a hydrocarbon-based anion exchange. The ion conductivity-imparting agent of the present invention is interposed between the membrane and the catalyst particles. Since this ion conductivity imparting agent has a large anion exchange capacity of 1.8 to 3.5 mmol / g, its water content is high. Therefore, even if the fuel gas supplied to the anode side has a low humidity, a large amount of water can be retained in the anode catalyst layer. As a result, not only high ion conductivity is exhibited in the entire anode catalyst layer, but also water necessary for the cathode electrode reaction is rapidly supplied from the anode side to the cathode, so that high battery output can be obtained. Furthermore, it is a reaction substrate that is supplied from the anode side to the cathode catalyst layer even if low-humidity fuel gas is supplied for a long time without installing a moisture supply device such as a humidifier in the fuel gas supply path of the anode. Water deficiency is unlikely to occur. Therefore, the high battery output is stably maintained. Furthermore, maintaining these stability is effective even when no water supply device is installed in the air supply path on the cathode side.

FIG. 1 is a conceptual diagram showing a basic structure of a polymer electrolyte fuel cell. FIG. 2 is a conceptual diagram showing the basic structure of the MEA of the present invention. FIG. 3 is a conceptual diagram showing another basic structure of the MEA of the present invention.

(Ion conductivity imparting agent)
In the present invention, the ion conductivity imparting agent is a material constituting the anode catalyst layer of the anion exchange membrane fuel cell. The ion conductivity-imparting agent of the present invention is used by being added to the inside of the anode catalyst layer or applied to the joining surface of the anode catalyst layer when joining the hydrocarbon-based anion exchange membrane and the anode catalyst layer. The

  The ion conductivity-imparting agent of the present invention has the effect of increasing the conductivity of ions in the anode catalyst layer or in the vicinity of the junction surface between the anode catalyst layer and the hydrocarbon-based anion exchange membrane, and by maintaining a high concentration of moisture. The effect of stably maintaining the water supply from the same part to the cathode is extremely high.

  The ion conductivity-imparting agent of the present invention comprises a hydrocarbon-based anion exchange resin having an anion exchange capacity within a predetermined range. The ion conductivity-imparting agent of the present invention may be composed of a solution of this hydrocarbon-based anion exchange resin or a suspension thereof.

  The hydrocarbon-based anion exchange resin used in the ion conductivity-imparting agent of the present invention has an anion exchange capacity within a predetermined range, has at least one anion exchange group in the molecule, and is difficult to water. It is a soluble and elastic hydrocarbon-based anion exchange resin. Such a hydrocarbon-based anion exchange resin can be synthesized by a known method.

  The anion exchange capacity of the hydrocarbon-based anion exchange resin is 1.8 to 3.5 mmol / g, preferably 1.9 to 3.0 mmol / g, and 2.0 to 2.8 mmol / g. It is particularly preferred that A hydrocarbon-based anion exchange resin having an anion exchange capacity in this range has high anion conductivity. Furthermore, since the water content is high, a hydrocarbon-based anion exchange resin having such anion exchange capacity can be used to supply a large amount to the anode catalyst layer even when a fuel cell is operated by supplying low humidity fuel gas. It becomes possible to retain moisture. As a result, a high battery output can be obtained even under the operating conditions, and the high battery output can be stably maintained even if the operation at the low humidity is continued for a long period of time.

  When the anion exchange capacity of the hydrocarbon-based anion exchange resin is less than 1.8 mmol / g, the water retention amount of the anode catalyst layer under low humidity becomes insufficient. In addition, the battery output is likely to decrease, and it becomes difficult to stably maintain the battery output. On the other hand, when the anion exchange capacity of the hydrocarbon-based anion exchange resin exceeds 3.5 mmol / g, swelling due to moisture absorption increases, which may inhibit the diffusion of fuel and oxidant gas. Furthermore, the solubility in water is increased and the anode catalyst layer is easily eluted.

  The above hydrocarbon-based anion exchange resin has an anion exchange capacity within the above range, and the moisture content measured by the method described below is usually 35 to 100% under a relative humidity of 90%, preferably It can be 38 to 90%, particularly preferably 40 to 80%. Furthermore, even under a low humidity of 40% relative humidity, it can be maintained usually at 7 to 25%, preferably 8 to 20%, particularly preferably 9 to 18%.

  By using such a hydrocarbon-based anion exchange resin having a high water content for the anode catalyst layer of an anion exchange membrane fuel cell, high battery output can be obtained even when the fuel gas is operated at low humidity, and It is possible to stably maintain a high battery output. Even on the anode side where water is generated, when the fuel gas is at low humidity, it is estimated that the water content of the anode is increased to maintain good ionic conductivity, but high battery output and battery In order to make the output stability compatible, it is difficult to explain only the effect of increasing the ionic conductivity of the anode catalyst layer. That is, since it becomes possible to hold a sufficient amount of water in the anode catalyst layer of the present invention, water consumed in the cathode electrode reaction can be quickly supplied from the anode side to the catalyst active point. As a result, the battery output is increased. Furthermore, since the operation can be performed without causing the deficiency of water even when the operation is performed for a long time, the output stability is improved. As described above, high battery output and output stability can be achieved not only by improving the ionic conductivity by simply increasing the water content but also by promoting the movement of water from the anode side to the cathode. Presumed.

  In the present invention, the hydrocarbon-based anion exchange resin means an anion exchange resin in which most of the molecules other than the ion exchange groups present in the molecule are composed of hydrocarbon groups. However, as long as the effect of the present invention is not hindered, atoms other than carbon atoms and hydrogen atoms may be contained in a portion other than the anion exchange group in the molecule. For example, in addition to carbon-carbon bond and carbon = carbon bond (double bond) as bonds constituting the main chain and side chain of the molecule, oxygen, nitrogen introduced by ether bond, ester bond, amide bond, siloxane bond, etc. , Atoms such as silicon, sulfur, boron and phosphorus. Such atoms may be contained in such an amount that the total number of atoms constituting the molecule is 40% or less, preferably 10% or less. If the number of hydrogen atoms constituting the molecule is 40% or less, preferably 10% or less, chlorine, bromine, fluorine, iodine, or other atoms are bonded directly or as a substituent to the main chain and side chain. Also good.

  The anion exchange group present in the hydrocarbon-based anion exchange resin is not particularly limited as long as it is a substituent having anion exchange ability, but a quaternary ammonium base, a pyridinium base, an imidazolium base, a tertiary base. Examples include amino groups and phosphonium groups. Among these, a quaternary ammonium base or a pyridinium base is preferable from the viewpoint of strong basicity.

Further, the counter ion of the anion exchange group of the hydrocarbon-based anion exchange resin is preferably OH ⁻ , HCO ₃ ⁻ or CO ₃ ²⁻ or a mixed form thereof. When the counter ion is in the ionic form, the ion conductivity of the anion exchange resin can be increased, and the anode electrode reaction can be advanced with high efficiency. HCO ₃ ⁻ and CO ₃ ²⁻ are particularly preferable as the counter ion from the viewpoint of enhancing the safety of the operation for converting the counter ion to the ionic form and the chemical stability of the obtained anion exchange resin.

  The hydrocarbon-based anion exchange resin is preferably hardly soluble in water. In the case of being easily dissolved in water, when the fuel cell is configured and used, the hydrocarbon-based anion exchange resin is eluted from the catalyst layer, and the battery performance is deteriorated. Therefore, in Patent Document 7, the solubility of the hydrocarbon-based anion exchange resin used as an ion conductivity imparting agent in water at 20 ° C. (the concentration of the hydrocarbon-based anion exchange resin in the saturated solution) is 1 It is required to be less than mass%, preferably 0.8 mass% or less (paragraph [0016]). Specifically, in the examples, the hydrocarbon anion exchange resin having an anion exchange capacity of 0.8 to 1.3 mmol / g has a solubility in water of 20 ° C. of 0.02 to 0.04 mass. % Are used. In contrast, the hydrocarbon-based anion exchange resin used as the ion conductivity-imparting agent in the present invention has a large anion exchange capacity of 1.8 to 3.5 mmol / g. However, with this level of anion exchange capacity, the solubility in water is acceptable, usually 0.3% by mass or more, and in some cases 0.4% by mass or more, but less than 1% by mass ( Preferably, it can be suppressed to 0.8% by mass or less. The hydrocarbon-based anion exchange resin used as the ion conductivity-imparting agent in the present invention is preferably non-crosslinked. The non-crosslinked hydrocarbon anion exchange resin is excellent in dispersibility with the catalyst and can be easily made into a solution, and therefore has high applicability. Further, since the non-crosslinked hydrocarbon-based anion exchange resin is flexible, it has excellent bonding properties with the hydrocarbon-based ion exchange membrane.

  The hydrocarbon-based anion exchange resin preferably has an appropriate elastic modulus. Specifically, the Young's modulus at 25 ° C. is preferably 1 to 300 MPa, and particularly preferably 3 to 100 MPa. By having such an elastic modulus, adhesion between the hydrocarbon-based anion exchange resin and the cathode catalyst layer can be improved. Further, when the fuel cell is configured and used, the stress generated by the heat cycle can be dispersed, and the durability of the fuel cell can be greatly improved.

  The hydrocarbon-based anion exchange resin used in the present invention is used as an ion conductivity imparting agent used for forming the anode catalyst layer as it is or as a solution or suspension. It is applied to a surface to be a bonding surface of the anode catalyst layer, or is blended with an anode catalyst layer forming composition (described later) containing an anode catalyst (platinum group catalyst or the like). From the viewpoint that a hydrocarbon-based anion exchange resin can be uniformly present in the anode catalyst layer or in the vicinity of the bonding surface, and an anode catalyst layer having good bonding properties and high activity can be created. The anion exchange resin is preferably used in a solution state.

  For these reasons, it is preferable that the hydrocarbon-based anion exchange resin is soluble in an organic solvent. The organic solvent is not particularly limited, and may be appropriately selected from the following solvents, for example.

  Alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, t-butanol, 1-hexanol, cyclohexanol, 2-ethoxyethanol; ketones such as acetone, methyl ethyl ketone; ethyl acetate, isobutyl acetate, etc. Esters of nitriles such as acetonitrile and malonnitrile; Amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidinone; Sulfoxides such as dimethyl sulfoxide and sulfolane; Diethyl ether And solvents such as ethers such as 1,2-dimethoxyethane, tetrahydrofuran and dioxane; hydrocarbons such as hexane, toluene and benzene; and chlorinated hydrocarbons such as chloroform and dichloromethane. These may be used alone or in combination of two or more. These solvents may contain water. One or two or more selected from ethanol, 1-propanol, tetrahydrofuran and chloroform from the viewpoint of easy drying operation, familiarity with hydrocarbon anion exchange membranes and good dispersibility with catalysts. It is preferable that it is a combination.

  The solubility of the hydrocarbon-based anion exchange resin in an organic solvent (the concentration of the hydrocarbon-based anion exchange resin in a saturated solution at 20 ° C.) is preferably 1% by mass or more, and preferably 3% by mass or more. Is particularly preferred. When the ion conductivity-imparting agent is in a solution state, the concentration of the hydrocarbon-based anion exchange resin in the solution is not particularly limited, but is usually 1 to 20% by mass, and preferably 2 to 15% by mass. . This concentration may be appropriately determined according to the combination of the solvent and the hydrocarbon-based anion exchange resin, the amount used for the anode catalyst, the viscosity, the permeability during application, and the like.

  When the hydrocarbon-based anion exchange resin is used as a suspension, the dispersion medium is not particularly limited, but a solvent or water that does not dissolve the hydrocarbon-based anion exchange resin among the above organic solvents is used. Further, the content of the hydrocarbon-based anion exchange resin in the suspension is not particularly limited, but is preferably set to the same level as that in the solution state.

  The hydrocarbon-based anion exchange resin used in the present invention may be appropriately selected from those conventionally known as anion exchange resins, or may be synthesized and used. In general, the solubility in water and organic solvents and the Young's modulus are controlled by the amount of anion exchange groups present in the hydrocarbon-based anion exchange resin, the molecular weight, the degree of crosslinking, and the main chain structure of the resin. Therefore, when selecting the hydrocarbon-based anion exchange resin, it is preferable to select with attention to such points. Moreover, the above factors can be easily adjusted by changing the synthesis conditions in a general synthesis method of a hydrocarbon-based anion exchange resin having an anion exchange group. The method for synthesizing the hydrocarbon-based anion exchange resin used in the present invention is not particularly limited, but can be easily synthesized, for example, by the following method.

  The hydrocarbon-based anion exchange resin has a property of dissolving a monomer having a functional group into which an anion exchange group can be introduced or a monomer having an anion exchange group and a conjugated diene compound in an organic solvent and water. Polymerization is performed so as to satisfy the above conditions. Thereafter, when a monomer having a functional group capable of introducing an anion exchange group is used, an anion exchange group introduction treatment is performed. The hydrocarbon-based anion exchange resin can be easily synthesized by adjusting the types and combinations and amounts of the monomers used; the amount of anion exchange groups introduced; the degree of polymerization of the polymer, and the like.

  Examples of the monomer having a functional group into which an anion exchange group can be introduced include aromatic vinyl compounds such as styrene, α-methylstyrene, chloromethylstyrene, vinylpyridine, vinylimidazole, and vinylnaphthalene. From the viewpoint of easy introduction of an anion exchange group, styrene and α-methylstyrene are preferable. As monomers having an anion exchange group, amino group-containing aromatic vinyl compounds such as vinylbenzyltrimethylamine and vinylbenzyltriethylamine; nitrogen-containing heterocyclic monomers such as vinylpyridine and vinylimidazole; salts thereof and the like Examples are esters.

  Examples of the conjugated diene compound include butadiene, isoprene, chloroprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. The amount used is not particularly limited, but the content of the conjugated diene compound unit in the hydrocarbon-based anion exchange resin is 5 to 85% by mass, and generally 10 to 75% by mass.

  In addition to the above-mentioned monomer having a functional group capable of introducing an anion exchange group, a monomer having an anion exchange group, and a conjugated diene compound, a crosslinkable copolymer with these monomers as required A sex monomer may be added. Although it does not restrict | limit especially as a crosslinkable monomer, For example, Divinylbenzenes; Polyfunctional vinyl compounds, such as divinyl sulfone, divinyl biphenyl, and trivinylbenzene; Trimethylol methane trimethacrylate, Methylenebisacrylamide, Hexamethylene Examples are polyfunctional methacrylic acid derivatives such as dimethacrylamide. When these crosslinkable monomers are used, the amount used is generally based on 100 parts by mass of a monomer having a functional group into which an anion exchange group can be introduced or a monomer having an anion exchange group. It is selected from 0.01 to 5 parts by mass, preferably 0.05 to 1 part by mass. When the crosslinkable monomer is 0.01 parts by mass or less, the resulting hydrocarbon polymer having an anion exchange group is likely to be soluble in water. Further, when the crosslinkable monomer is 5 parts by mass or more, it is easily insoluble in an organic solvent.

  In addition to the monomer having a functional group into which the anion exchange group can be introduced, a monomer having an anion exchange group, a conjugated diene compound or a crosslinkable monomer, these monomers may be used as necessary. Other monomers copolymerizable with may be added. Examples of such other monomers include vinyl compounds such as ethylene, propylene, butylene, acrylonitrile, vinyl chloride, and acrylic acid esters. The amount used is preferably 0 to 100 parts by mass with respect to 100 parts by mass of the monomer having a functional group into which an anion exchange group can be introduced or the monomer having an anion exchange group.

  As the polymerization method, known polymerization methods such as solution polymerization, suspension polymerization, and emulsion polymerization are employed. The polymerization method is not particularly limited, and may be appropriately selected according to the composition of the monomer composition. When the above exemplified monomers such as styrene are used, the polymerization is preferably performed under polymerization conditions such that the average molecular weight is 10,000 to 1,000,000, preferably 50,000 to 400,000. When a monomer having an anion exchange group is used, the hydrocarbon-based anion exchange resin used in the present invention can be obtained by performing polymerization in this manner. In addition, when a monomer having a functional group into which an anion exchange group can be introduced is used, the polymer obtained by such polymerization is subjected to desired anion exchange by various known methods such as amination and alkylation. By introducing a group, the hydrocarbon-based anion exchange resin used in the present invention can be obtained.

In the above method, the hydrocarbon-based anion exchange resin is often obtained using halogen ions as counter ions. In the present invention, the ion conductivity-imparting agent may be a hydrocarbon-based anion exchange resin having the halogen ion as a counter ion. However, the halogen ion is previously converted to OH ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ . It is preferable to use an ion-exchanged hydrocarbon anion exchange resin. When the former ion conductivity-imparting agent is used, after producing a catalyst layer and MEA described later, the halogen ions are ion-exchanged into OH ⁻ , HCO ₃ ⁻ , and CO ₃ ²⁻ . The ion exchange method is not particularly limited, and a known method can be used. For example, a hydrocarbon system in which an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, or the like is used as a counter ion. It can be performed by immersing the anion exchange resin for 2 to 10 hours. From the viewpoint of operational safety and stability of the obtained anion exchange resin, it is most preferable to use HCO ₃ ⁻ and CO ₃ ²⁻ forms.

  Among the above methods, since the highly effective hydrocarbon-based anion exchange resin can be easily obtained, the hard segment and the soft segment are selected by selecting a plurality of types of monomers from the monomers described above. After forming a so-called thermoplastic elastomer by block copolymerization (usually, the polymer block of the aromatic vinyl compound forms a hard segment and the polymer block of a conjugated diene compound forms a soft segment), an anion In the case of using a monomer having a functional group into which an exchange group can be introduced, a method of performing an anion exchange group introduction treatment is particularly suitable.

  In this case, a combination of monomers to be copolymerized may be determined according to a general method for synthesizing a thermoplastic elastomer, and polymerization may be performed according to a conventional method. Examples of thermoplastic elastomers into which anion exchange groups can be introduced include polystyrene-polybutadiene-polystyrene triblock copolymer (SBS), polystyrene-polyisoprene-polystyrene triblock copolymer (SIS), and SBS and SIS, respectively. Examples include hydrogenated polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer (SEBS) and polystyrene-poly (ethylene-propylene) -polystyrene triblock (SEPS) copolymer. Examples of the thermoplastic elastomer having an anion exchange group include a polystyrene-polyvinylpyridine-polybutadiene triblock copolymer and a polystyrene-polyvinylpyridine-polyisoprene triblock copolymer. What is necessary is just to employ | adopt the combination of the monomer which gives such a copolymer. In addition, as a thermoplastic elastomer into which an anion exchange group can be introduced, SEBS and SEPS are preferable from the viewpoint of stability in the step of introducing an ion exchange group.

  The monomer composition at the time of polymerization is not particularly limited, but the content of the aromatic vinyl compound unit in the block copolymer is preferably 5 to 70% by mass from the viewpoint of electrical characteristics and mechanical characteristics. 10 to 50% by mass is particularly preferable.

  The copolymerization method of the aromatic vinyl compound and the conjugated diene compound is not particularly limited, and a known method such as anionic polymerization, cationic polymerization, coordination polymerization, radical polymerization or the like is employed. Living anionic polymerization is particularly preferred because it is easy to control the block structure. The form of block copolymerization may be any of diblock copolymerization, triblock copolymerization, radial block copolymerization, and multiblock copolymerization, but the end blocks aggregate together to form a domain. Triblock copolymerization is preferred because it is easy. In addition, for the reason that it is easy to mold and process like a thermoplastic resin, the average molecular weight of each block copolymer is from 50,000 to 300,000, particularly 10,000 to 150,000. preferable. When hydrogenating the conjugated diene portion of the block copolymer, it is preferable to add hydrogen so that the hydrogenation rate is 95% or more. When using a monomer having a functional group into which an anion exchange group can be introduced, the anion exchange group can be introduced in the same manner as described above.

  In the present invention, the ion conductivity-imparting agent is used in the anode catalyst layer of an anion exchange type fuel cell using a hydrocarbon-based anion exchange membrane as a solid polymer electrolyte membrane. Moisture consumed by the cathode electrode reaction can be supplied from the anode side quickly and without deficiency over a long period of time. This is particularly effective when supplying fuel gas at low humidity.

(Anode catalyst layer)
The anode catalyst layer in the present invention comprises an anode catalyst and the ion conductivity imparting agent.

  As the anode catalyst, a known catalyst that accelerates the oxidation reaction of fuel such as hydrogen or methanol can be used without any particular limitation. Examples of such an anode catalyst include metal particles such as platinum, gold, silver, palladium, iridium, rhodium, ruthenium, osmium, tin, iron, cobalt, nickel, molybdenum, tungsten, vanadium, and alloys thereof. . These are used alone or as an alloy containing one or more. Since the catalytic activity is excellent, it is preferable to use a platinum group catalyst (ruthenium, rhodium, palladium, osmium, iridium, platinum) or an alloy of the platinum group catalyst and a non-noble metal. In the case of an alloy with a non-noble metal, examples of the non-noble metal element include titanium, manganese, iron, cobalt, nickel, and chromium.

  The particle size of the metal or the like serving as the anode catalyst is usually 0.1 to 100 nm, preferably 0.5 to 10 nm. The smaller the particle size, the higher the catalyst performance, but those having a particle size of less than 0.5 nm are difficult to produce. If it is larger than 100 nm, it is difficult to obtain sufficient catalyst performance.

These anode catalysts may use the above metal particles or the like as they are, or may be used after being previously supported on a conductive agent. The conductive agent is not particularly limited as long as it is an electronic conductive material. For example, carbon black such as furnace black and acetylene black, activated carbon, and graphite are generally used alone or in combination. The catalyst content is a metal mass per unit area in a state where the anode catalyst layer is in a sheet form, and is usually 0.01 to 10 mg / cm ² , and preferably 0.1 to 5.0 mg / cm ² .

  These anode catalyst particles are mixed with the above anionic conductivity-imparting agent and, if necessary, a binder or a dispersion medium to prepare a composition for forming an anode catalyst layer. A layer is bonded to one surface of the anion exchange membrane.

  The composition for forming an anode catalyst layer may contain a binder, a conductive agent not supporting the anode catalyst, and the like in addition to the anode catalyst and the conductive agent supporting the anode catalyst. When the ion conductivity-imparting agent of the present invention is in a solution state, the composition for forming an anode catalyst layer includes the ion conductivity-imparting agent in order to adjust the amount of supported catalyst and the film thickness of the anode catalyst layer. A solvent similar to the solvent used may be further added during the preparation of the composition to adjust its viscosity. Furthermore, for the purpose of preventing heat generation due to contact between the catalyst and the organic solvent, a conductive agent carrying the catalyst and water may be mixed and mixed with the above-described ion conductivity-imparting agent.

  Here, the binder is a substance for forming an anode catalyst layer and maintaining the shape, and a thermoplastic resin is generally used. The thermoplastic resins include polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyether ether ketone, polyether sulfone, styrene / butadiene copolymer, and acrylonitrile / butadiene copolymer. Illustrated. The content of the binder in the anode catalyst layer is preferably 0 to 25% by mass of the anode catalyst layer so as not to hinder the property of the anode catalyst layer that is easily wetted. Moreover, it is preferable that content of this binder in an anode catalyst layer is 10 mass parts or less with respect to 100 mass parts of catalyst particles. A binder may be used independently and may mix and use two or more types. As the conductive agent not supporting the catalyst, those exemplified as the conductive agent supporting the above-described catalyst can be used.

  The composition for forming an anode catalyst layer preferably contains 1 to 70% by mass of the ion conductivity-imparting agent, and particularly preferably 2 to 50% by mass. The composition for forming an anode catalyst layer preferably contains 0.5 to 99% by mass, and particularly preferably 1 to 97% by mass, of the anode catalyst in terms of metal. When the anode catalyst supported on the conductive agent is used, the conductive agent content is not limited as long as the anode catalyst metal content is within the above range. The ratio of the anode catalyst in the composition for forming an anode catalyst layer (when the anode catalyst is supported on a conductive agent, the total mass of the conductive agent and the anode catalyst) to the ion conductivity imparting agent (anode The catalyst / ion conductivity imparting agent) is preferably 99/1 to 20/80 by mass ratio, and more preferably 98/2 to 40/60.

  A method for preparing the anode catalyst layer forming composition is not particularly limited, and a method known in the art is employed. For example, the above-described ion conductivity-imparting agent and a catalyst or a conductive agent carrying a catalyst are mixed, and mixed and dispersed for 1 to 24 hours by stirring or ultrasonic dispersion using a stirrer, ball mill, kneader or the like. And a method for preparing a composition for forming an anode catalyst layer.

  The anode catalyst layer of the present invention is produced by forming the anode catalyst layer forming composition into a desired shape and then removing the solvent. The method for forming the anode catalyst layer of the present invention is not particularly limited, and methods known in the art are employed.

  For example, a method of applying the anode catalyst layer forming composition to a support material and drying, or a method of applying the anode catalyst layer forming composition to a release sheet made of polytetrafluoroethylene and drying the composition, Examples include a method in which the composition for forming an anode catalyst layer is directly applied to a hydrocarbon-based anion exchange membrane and dried. As a drying method, a generally known method such as standing at room temperature or air drying at a temperature lower than the boiling point of the organic solvent can be used without limitation.

  The anode catalyst layer of the present invention can also be formed by printing a composition for forming an anode catalyst layer by a method such as screen printing, gravure printing or spray printing and then drying it.

  The drying time is usually about 0.1 to 24 hours at room temperature, although it depends on the solvent contained in the anode catalyst layer forming composition. As needed, you may dry about 0.1 to 5 hours under reduced pressure.

  Usually, application | coating or printing is performed so that the thickness of the anode catalyst layer after drying may be 5-50 micrometers.

  A porous material is used as the support material. Specifically, carbon fiber woven or non-woven fabric, carbon paper or the like is used. The thickness of the support material is preferably 50 to 300 μm, and the porosity is preferably 50 to 90%. These supporting materials may be subjected to a water repellent treatment by a conventionally known method. Further, the conductive porous layer (hereinafter referred to as “MPL”) composed of a conductive agent for supporting the catalyst and a binder having a water repellent action such as polytetrafluoroethylene is used as the catalyst. You may use, after forming on the surface in which a layer is formed. The support material on which MPL is formed is particularly suitable for use on the anode side where water is generated by an electrode reaction. These supporting materials have electronic conductivity, and also have a role of transmitting the output of the fuel cell from the catalyst layer to the outside. When the composition for forming an anode catalyst layer is supported on a support material, it is filled and adhered in the voids or on the joint surface with the anion exchange membrane.

  As the release sheet, a resin sheet having excellent peelability and a smooth surface is preferably used. In particular, a sheet of polytetrafluoroethylene or polyethylene terephthalate having a thickness of 50 to 200 μm is preferable.

(Cathode catalyst)
The cathode catalyst layer of the present invention comprises a cathode catalyst and an ion conductivity imparting agent. As the cathode catalyst, a known catalyst that promotes the reduction reaction of oxygen can be used without particular limitation. Examples of such cathode catalysts include metal particles such as platinum, gold, silver, palladium, iridium, rhodium, ruthenium, osmium, tin, iron, cobalt, nickel, molybdenum, tungsten, vanadium, and alloys thereof. . It is preferable to use a platinum group catalyst (ruthenium, rhodium, palladium, osmium, iridium, platinum) or silver because of its excellent catalytic activity. These are used alone or as an alloy containing one or more. In the case of an alloy with a non-noble metal, examples of the non-noble metal element include titanium, manganese, iron, cobalt, nickel, and chromium.
As the cathode catalyst, various metal oxides can be used as the catalyst. For example, a perovskite oxide represented by ABO ₃ having excellent oxidation activity can also be used suitably. Specifically, LaMnO ₃ , LaFeO ₃ , LaCrO ₃ , LaCoO ₃ , LaNiO _3, etc .; a part of the A site partially substituted with Sr, Ca, Ba, Ce, Ag, etc .; Examples in which a part is partially substituted with Pd, Pt, Ru, Ag, etc. are exemplified.

  Moreover, the ion conductivity imparting agent used for forming the cathode catalyst layer is not particularly limited. For example, a hydrocarbon anion exchange resin having an anion exchange capacity of 0.5 to 1.5 mmol / g shown in Patent Document 7 can be used, and the anion used for the anode catalyst layer in the present invention can be used. A hydrocarbon-based anion exchange resin having an exchange capacity of 1.8 to 3.5 mmol / g can also be used. In addition, the various requirements described for the anode catalyst layer are also applied in accordance with the formation of the cathode catalyst layer.

(MEA)
An MEA for an anion exchange membrane fuel cell of the present invention has a structure comprising a hydrocarbon anion exchange membrane and the anode catalyst layer formed on one surface of the hydrocarbon anion exchange membrane. Comprising. That is, the MEA of the present invention is an MEA in which an anode catalyst layer is bonded to one surface of a hydrocarbon-based anion exchange membrane, and the ion-exchange membrane is interposed between the hydrocarbon-based anion exchange membrane and the anode catalyst layer. A conductivity-imparting agent is present.

  FIG. 2 is a conceptual diagram showing the basic structure of the MEA of the present invention. In FIG. 2, 20 is an MEA, and 25 is a hydrocarbon-based anion exchange membrane. An anode catalyst layer 23 is formed on one surface of the hydrocarbon-based anion exchange membrane 25. A cathode catalyst layer 27 is formed on the other surface of the hydrocarbon-based anion exchange membrane 25. The anode catalyst layer 23 is formed from the ion conductivity-imparting agent of the present invention and anode catalyst particles.

  FIG. 3 is a conceptual diagram showing another basic structure of the MEA of the present invention. In FIG. 3, 30 is an MEA, and 35 is a hydrocarbon-based anion exchange membrane. An anode catalyst layer 34 is formed on one surface of the hydrocarbon-based anion exchange membrane 35. A cathode catalyst layer 36 is formed on the other surface of the hydrocarbon-based anion exchange membrane 35. The anode catalyst layer 36 is formed using anode catalyst particles and the ion conductivity-imparting agent of the present invention as essential components. Reference numerals 33 and 37 in FIG. 3 denote gas diffusion layers.

(I) Hydrocarbon Anion Exchange Membrane In the present invention, a known anion exchange membrane can be used as the hydrocarbon anion exchange membrane (hereinafter sometimes abbreviated as “anion exchange membrane”). . In particular, it is preferable to use an anion exchange membrane in which a porous membrane is used as a base material and an air gap is filled with an anion exchange resin. By using an anion exchange membrane based on such a porous membrane, the porous membrane functions as a reinforcing member, so that the physical strength of the anion exchange membrane is increased without sacrificing electrical resistance. be able to.

  In the present invention, as the porous membrane serving as the base material of the anion exchange membrane, a known membrane that can be used as the base material of the ion exchange membrane can be used without limitation. Specifically, a porous film, a nonwoven fabric, a woven fabric, paper, a non-woven paper, an inorganic film, etc. can be mentioned. The material of these porous membranes is not particularly limited, and thermoplastic resins, thermosetting resins, inorganic materials, and mixtures thereof can be used. Among these porous membranes, a porous membrane made of polyolefin (from the viewpoint of easy production, excellent mechanical strength, chemical stability and chemical resistance, and good compatibility with anion exchange resins) Hereinafter, it is preferable to use a “polyolefin-based porous membrane”.

  Examples of such polyolefin-based porous membrane include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 4-methyl-1-pentene, and 5-methyl-1-heptene. The thing manufactured from the polyolefin obtained by homopolymerizing or copolymerizing alpha olefins, etc. is illustrated. Among these, a porous film made of polyethylene or polypropylene is preferable, and a porous film made of polyethylene is particularly preferable.

  Such a polyolefin-based porous membrane can be obtained, for example, by a method described in JP-A-9-216964, JP-A-2002-338721, or the like, or a commercially available product such as Asahi Kasei's trade name “ It can also be obtained as "Hypore", Ube Industries product name "Yupor", Toray Battery Separator Film product name "Setilla", Mitsubishi Plastics product name "Exepor".

  The average pore diameter of such a polyolefin-based porous membrane is generally 0.005 to 5.0 μm and 0.01 to 1.0 μm in view of the small membrane resistance and mechanical strength of the obtained anion exchange membrane. More preferably, it is 0.015-0.4 micrometer. Further, the porosity of the polyolefin-based porous membrane is generally 20 to 95%, preferably 30 to 80%, and most preferably 30 to 50% for the same reason as the average pore diameter.

  Furthermore, the thickness of the porous membrane that is the base material of the anion exchange membrane is generally 3 to 200 μm, and preferably 5 to 60 μm from the viewpoint of obtaining a membrane having a lower membrane resistance. Considering the balance between the low permeability and the required mechanical strength, it is most preferably 7 to 40 μm.

  The anion exchange resin filled in the voids of the porous membrane is not particularly limited, but considering the familiarity and adhesion with the porous membrane, the resin portion excluding the anion exchange group is crosslinked. It is preferable that it is comprised with the made hydrocarbon polymer. Here, the hydrocarbon-based polymer is a polymer that does not substantially contain a carbon-fluorine bond, and most of the main chain and side chain bonds constituting the polymer are carbon-carbon bonds. Point to. This hydrocarbon polymer contains a small amount of other atoms such as oxygen, nitrogen, silicon, sulfur, boron, and phosphorus due to ether bonds, ester bonds, amide bonds, siloxane bonds, etc. between carbon-carbon bonds. It may be. Further, the atoms bonded to the main chain and the side chain do not need to be all hydrogen atoms, and if the amount is small, other atoms such as chlorine, bromine, fluorine, iodine, etc., or substituents containing other atoms May be substituted. The amount of these elements other than carbon and hydrogen is 40 mol% or less, preferably 10 mol% or less, based on all elements constituting the resin (polymer) excluding the anion exchange group.

  In the present invention, the anion exchange group in the anion exchange membrane (anion exchange group possessed by the anion exchange resin filled in the voids of the porous membrane) is not particularly limited, but is easy to manufacture, Considering availability, etc., a quaternary ammonium base or a pyridinium base is preferable.

  The specific manufacturing method of an anion exchange membrane is illustrated below. First, a polymerizable monomer having a halogenoalkyl group (for example, chloromethylstyrene, bromomethylstyrene, iodomethylstyrene), a crosslinkable polymerizable monomer (for example, a divinylbenzene compound), and an effective amount of a polymerization initiator ( For example, by bringing a polymerizable composition containing an organic oxide) into contact with the porous film, the voids of the porous film are filled with the polymerizable composition. Thereafter, the polymerizable composition filled in the voids is polymerized and cured, and then an anion exchange membrane can be produced by converting a halogenoalkyl group into the anion exchange group (hereinafter referred to as “contact weight”). Also called “legal”). In this contact polymerization method, an epoxy compound or the like can be blended with the polymerizable composition.

  The other manufacturing method of an anion exchange membrane is illustrated. In the catalytic polymerization method, in place of the polymerizable monomer having a halogenoalkyl group, a polymerizable monomer having a functional group capable of introducing a halogenoalkyl group such as styrene is used, as described above, and a polymerizable composition The product is polymerized and cured. Thereafter, an anion exchange membrane can be produced by introducing a halogenoalkyl group into a functional group into which a halogenoalkyl group can be introduced, and then changing the introduced halogenoalkyl group to an anion exchange group.

  Further, for example, another method for producing an anion exchange membrane uses a polymerizable monomer having an anion exchange group introduced therein instead of the polymerizable monomer having a halogenoalkyl group in the catalytic polymerization method. Then, as described above, an anion exchange membrane can be produced by polymerizing and curing the polymerizable composition.

  In the present invention, the anion exchange membrane is produced by the catalytic polymerization method so that the obtained membrane has sufficient adhesion and ion exchange capacity and can sufficiently suppress the permeation of fuel. It is preferable.

In addition, when the anion exchange membrane is produced by the above-described production method, the hydrocarbon-based anion exchange membrane is often obtained as a counter ion of an anion exchange group as a halogen ion. In this case, the anion exchange membrane using the halogen ion as a counter ion is immersed in an excess amount of an alkaline aqueous solution, for example, so that the counter ion is in any of the OH ⁻ , HCO ₃ ⁻ , and CO ₃ ²⁻ forms, or It is preferable to ion-exchange these mixed forms. There is no special restriction | limiting in this ion exchange method, The well-known method according to a counter ion is employable. For example, anion exchange in which an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate or the like is used as a counter ion with the above halogen ion The method of immersing a film | membrane for 2 to 10 hours is mentioned. From the viewpoint of operational safety and the stability of the obtained anion exchange membrane, it is most preferable that the counter ion is in the HCO ₃ ⁻ and CO ₃ ²⁻ forms.

In the present invention, the anion exchange membrane usually has an anion exchange capacity of 0.2 to 3 mmol / g, preferably 0.5 to 2.5 mmol / g. Moreover, it is preferable to adjust so that the moisture content at 25 ° C. is 7% or more, and preferably about 10 to 90% so that the anion conductivity lowers due to drying. From the viewpoint of keeping the electrical resistance low and imparting the mechanical strength necessary for the support film, the film thickness preferably has a thickness of usually 5 to 200 μm, more preferably 10 to 100 μm. The breaking strength is preferably 0.08 MPa or more. The anion exchange membrane used in the present invention having these properties has a membrane resistance in an aqueous solution of 0.5 mol / L-sodium chloride at 25 ° C. of usually 0.05 to 1.5 Ω · cm ² , preferably It is 0.1-0.5 ohm * cm < ² > (refer Unexamined-Japanese-Patent No. 2007-188788 for the measuring method).

In the present invention, it is particularly preferable to use an anion exchange membrane having a water permeability of 1400 g · m ⁻² · hr ⁻¹ or more at 25 ° C. as an anion exchange membrane as in WO2009-081812. In combination with such an anion exchange resin membrane having a high water permeability, in the anode catalyst layer containing the anion exchange resin of the present invention, the movement of water from the anode side to the cathode is further promoted, and only the battery output. In addition, the effect is enhanced in terms of maintaining output stability.

Here, the water permeability refers to a 30 mass% ethanol aqueous solution at 25 ° C. on one side of the diaphragm using a hydroxide ion type fuel cell diaphragm, as will be described in detail in Examples described later. When the dry argon gas is supplied to the other surface of the diaphragm, the mass of water that permeates into the argon gas is measured. The higher the water permeability, the faster the water movement from the anode side to the cathode. Therefore, the water permeability at 25 ° C. of the anion-exchange membrane, more preferably 1600~5000g ^· m -2 ^{· hr -1,} and most preferably 1800~5000g ^· m -2 ^{· hr -1} . When the water permeability of the anion exchange membrane is larger than 5000 g · m ⁻² · hr ⁻¹ , it becomes difficult to obtain sufficient water resistance.

Such an anion exchange membrane having a water permeability of 1400 g · m ⁻² · hr ⁻¹ or more can be obtained by the production method described in detail in WO2009-081812. Specifically, it can be obtained by adjusting the thickness of the porous membrane, the porosity, and the degree of crosslinking of the anion exchange resin filled in the porous membrane in the catalytic polymerization method. In the production method, the water permeability of the obtained fuel cell membrane increases as the thickness of the porous membrane decreases, the porosity increases, and the crosslinking degree of the anion exchange resin to be filled decreases. . Combination of the thickness of the porous membrane, the porosity, and the degree of crosslinking of the anion exchange resin expressed by the amount of the crosslinkable polymerizable monomer in the polymerizable monomer mixture used for the preparation of the anion exchange resin described later Depending on the pore size of the porous membrane and the chemical structure of the anion exchange resin to be filled, for example, when the thickness of the porous membrane is 3 to 15 μm, the porosity is 20 to 95% and the degree of crosslinking is What is necessary is just to combine in the range of 0.4-15 mol%, and when the thickness of a porous film is more than 15 micrometers-50 micrometers, a porosity is 20-95% and a crosslinking degree is 0.1-4 mol%. What is necessary is just to combine in a range. Among them, a combination in which the thickness of the porous film is 3 to 15 μm, the porosity is 30 to 80%, the degree of crosslinking is 0.4 to 15 mol%, more preferably 1 to 10 mol% is preferable. Most preferably, a combination in which the thickness of the porous membrane is 5 to 15 μm, the porosity is 30 to 50%, the degree of crosslinking is 1 to 10 mol%, more preferably 1 to 4 mol% is preferable.

(Ii) Gas diffusion layer In the MEA of the present invention, an anode catalyst layer and / or a cathode catalyst layer is formed on the surface of a hydrocarbon-based anion exchange membrane, and a gas diffusion layer is formed on each catalyst layer as necessary. May be. When each catalyst layer is formed on the support material as described above and is not a catalyst layer, it is preferable to further form a gas diffusion layer in each catalyst layer. As the gas diffusion layer, a porous film such as carbon fiber woven fabric or carbon paper is usually used. The thickness of these gas diffusion layers is preferably 50 to 300 μm, and the porosity is preferably 50 to 90%.

  In addition, these gas diffusion layers may be subjected to water repellent treatment, or MPL may be provided on the surface facing the catalyst layer, similarly to the support material for the catalyst layer. In particular, the gas diffusion layer used on the anode side is preferably provided with water repellency treatment and MPL. When each catalyst layer has a catalyst layer formed on a support material, the support material functions as a gas diffusion layer, so it can be used without forming a gas diffusion layer. It is.

(Iii) Method for producing MEA The method for joining the anion exchange membrane and the anode catalyst layer is not particularly limited, and a method known in the art is employed.

  For example, the anode catalyst layer forming composition may be applied directly to an anion exchange membrane and dried, or the anode catalyst layer forming composition may be applied to the surface of a support material composed of a gas diffusion layer. A gas diffusion layer having the above structure, and a method of laminating and bonding the gas diffusion layer to an anion exchange membrane, and a method of transferring an anode catalyst layer prepared by applying to the release sheet by thermocompression bonding to the anion exchange membrane. Can be mentioned.

  That is, the MEA of the present invention is an MEA having an anode catalyst layer formed on one surface of the anion exchange membrane using the ion conductivity-imparting agent of the present invention. Since the catalyst layer constituting the MEA of the present invention is formed using the ion conductivity-imparting agent of the present invention, the ion conductivity and durability of the MEA can be further improved. Therefore, the anion exchange membrane fuel cell formed using the MEA of the present invention has high battery output and durability. On the other surface of the anion exchange membrane, a cathode catalyst layer is formed in the same manner as the anode catalyst layer.

  In the present invention, a specific MEA manufacturing method will be described.

  First, as described above, a method for producing the MEA of the present invention by directly applying the composition for forming an anode catalyst layer to an anion exchange membrane can be mentioned. In addition, the anode catalyst layer of the present invention is laminated with its catalyst supporting surface facing the anion exchange membrane, and if necessary, 40 to 200 ° C, preferably 60 to 180 ° C, more preferably 80 to 150 ° C. A method of producing the MEA of the present invention by performing thermocompression bonding in the temperature range of is mentioned. During lamination, the ion conductivity-imparting agent of the present invention may be further applied between the anion exchange membrane and the anode catalyst layer of the present invention. In addition, a catalyst layer not containing the ion conductivity-imparting agent of the present invention is prepared in advance, and the ion-conductivity imparting agent of the present invention is sandwiched between the anion exchange membrane and the catalyst layer. good.

  Thermocompression bonding is performed using an apparatus capable of pressurization and heating, such as a hot press machine and a roll press machine. Note that the above temperature range is a set temperature of a heating plate to be thermocompression bonded. The pressure for thermocompression bonding is preferably in the range of 1 to 20 MPa. The time for thermocompression bonding is not particularly limited.

  The MEA obtained by the above method can be incorporated into an anion exchange membrane fuel cell by a known method. The obtained anion exchange membrane fuel cell exhibits excellent durability and can maintain a high output voltage as shown in the following examples.

(Anion exchange membrane fuel cell)
The anion exchange membrane fuel cell of the present invention comprises the MEA.

  For example, the MEA produced as described above is mounted on the anion exchange membrane fuel cell having the basic structure as shown in FIG.

(Operating method of anion exchange membrane fuel cell)
An operation method of the anion exchange membrane fuel cell of the present invention will be described by taking a solid polymer electrolyte fuel cell having a basic structure as shown in FIG. 1 as an example. In the fuel cell, fuel is supplied to the fuel chamber 7 through the fuel circulation hole 2, while oxygen-containing gas is supplied to the oxidant chamber 8 through the oxidant gas circulation hole 3, thereby generating a power generation state. Here, since the higher output is obtained as the carbon dioxide content contained in the supplied fuel and the oxygen-containing gas is lower, it is preferable to remove carbon dioxide by a conventionally known method and then supply the fuel cell. When carbon dioxide is contained in the supply gas, it is dissolved in the anion exchange membrane and the anion exchange resin in the catalyst layer, and the output is lowered due to the decrease in the ionic conductivity of the electrolyte.

Fuel gas such as hydrogen gas is supplied to the fuel chamber 7. The fuel gas may be supplied after being diluted with an inert gas such as nitrogen or argon. The supply speed of the fuel gas to the fuel chamber is usually in the range of 1 to 1000 ml / min per 1 cm ^{2 of} electrode area.

  In the present invention, the relative humidity of the fuel gas is not particularly limited, but is approximately 0 to 100% RH at the operating temperature of the fuel cell.

  Generally, in an anion exchange membrane fuel cell, the relative humidity of the fuel gas supplied to the fuel chamber is adjusted using a humidifier or the like so as to be 70 to 100% RH. This is because the battery output may decrease when the relative humidity of the fuel gas supplied to the fuel chamber is less than 70% RH. Until now, it was estimated that the anion exchange resin membrane and the anode catalyst layer were dried and the ion conductivity was lowered.

  On the other hand, in the anion exchange membrane fuel cell of the present invention, the ion conductivity-imparting agent of the present invention is present in the anode catalyst layer constituting the MEA. And since this ion conductivity imparting agent has a high ability to retain water produced at the anode, it is possible to reduce the amount of water that escapes into the fuel gas, and the anode catalyst layer is kept highly wet. As a result, not only the ion conductivity of the anode catalyst layer is increased, but also the output and the stability of the output can be maintained high by promoting the movement of water from the anode side to the cathode. Therefore, in the anion exchange membrane fuel cell of the present invention, the relative humidity of the fuel gas supplied to the fuel chamber is not particularly limited, and the relative humidity under the operating conditions of the fuel cell may be less than 70%, for example. . When hydrogen is used as the fuel gas, in order to reduce the size and cost of the fuel cell, hydrogen gas is supplied as it is without passing through a humidifier or the like, or the fuel cell is operated with reduced power consumption. In this case, the relative humidity of the fuel gas is 0 to 40% RH at the operating temperature of the fuel cell.

The oxidant gas supplied to the oxidant chamber 8 may be any gas containing oxygen, and a conventionally known oxygen-containing gas can be used. The oxidant gas may be a gas composed only of oxygen or a mixed gas of oxygen and other inert gas. Nitrogen and argon are illustrated as an inert gas. The oxygen content in the mixed gas is preferably 10% by volume or more, and particularly preferably 15% by volume or more. In addition, since a high output is obtained so that oxygen content is high, it is preferable. An example of such a mixed gas is air. The supply rate of the oxygen-containing gas to the oxidant chamber may be usually in the range of ^{2 to} 2000 ml / min per 1 cm ^{2 of} electrode area.

  In the present invention, the relative humidity of the oxidant gas is not particularly limited, but is approximately 30 to 100% RH at the operating temperature of the fuel cell. When air is used as the oxidant gas, in order to reduce the size and cost of the fuel cell, it is preferable to take in the atmosphere as it is or to operate while suppressing the power consumption of the humidifier. The humidity is 10 to 60% RH at the operating temperature of the fuel cell.

  In the present invention, since the water content of the anion exchange resin as the ion conductivity-imparting agent used in the anode is high, not only the ion conductivity of the anode catalyst layer is increased, but also water transfer from the anode side to the cathode is promoted. . Therefore, not only when the fuel gas is operated at the low humidity, but also when the oxygen-containing gas is operated at a low humidity, specifically, when the relative humidity is 70% or less, the battery output and the stability of the output are improved. There is an effect to increase.

  The operating temperature is 0 ° C. to 90 ° C., more preferably 30 ° C. to 80 ° C. (cell temperature) considering the high output and durability of the material used.

  The operation of the anion exchange membrane fuel cell with the above requirements may be any system of constant current operation, constant voltage operation, and load variation operation. Regardless of which method is used, high power generation capability can be obtained at the beginning of operation. For example, in the constant current operation, the cell output voltage is usually 0.2 V or higher, more preferably 0.3 V or higher.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated, this invention is not limited to these Examples. In addition, the characteristic of the ion conductivity-imparting agent shown in an Example and a comparative example shows the value measured with the following method.

(1) Anion exchange capacity A solution (concentration 5.0 mass%, solution amount 2.5 g, hydrogen carbonate ion type) in which an ion conductivity-imparting agent is dissolved is cast on a Teflon (registered trademark) petri dish, and cast film Was made. Wash the cast film together with ion-exchanged water in a Visking tube (purchased from As One Co., Ltd.) that has been thoroughly washed with ion-exchanged water and dried under reduced pressure at 50 ° C. for 3 hours and measured (D _v (g)). Stuffed and tied both ends. The operation of immersing this tube in a 0.5 mol / L-HCl aqueous solution (50 mL) for 30 minutes or more was repeated three times, and the cast film inside was made a chloride ion type. Furthermore, this tube was immersed in ion-exchange water (50 mL), and the cast film inside was washed (10 times). Next, this tube was immersed in a 0.2 mol / L-NaNO ₃ aqueous solution (50 mL) for 30 minutes or more, the cast film inside was replaced with a nitrate ion type, and free chloride ions were extracted (four times). Further, chloride ions extracted by immersing this tube in ion-exchanged water (50 mL) for 30 minutes or more were collected (twice). All the solutions from which these chloride ions were extracted were collected and quantified with a potentiometric titrator (COMMITE-900, manufactured by Hiranuma Sangyo Co., Ltd.) using an aqueous silver nitrate solution (Amol). Next, the membrane after titration is immersed in a 0.5 mol / L-NaCl aqueous solution (50 g) for 30 minutes or more, washed thoroughly with ion-exchanged water, taken out of the tube, and kept in a dryer at 50 ° C. for 15 hours. After removing the water | moisture content, it dried under reduced pressure at 50 degreeC for 3 hours, and measured the weight ( _Dt (g)). Based on the measured value, the ion exchange capacity was determined by the following equation.

Anion exchange capacity [mmol / g-dry weight] = A × 1000 / (D _t −D _v )

(2) Moisture content Measuring device having a constant temperature and humidity chamber equipped with a magnetic floating balance (Nippon Bell, Inc.) a cast film made of an anion exchange resin and having a film thickness of about 50 to 70 μm prepared by the same method as described above. (MSB-AD-V-FC)). First, the film weight (D _dry (g)) after drying under reduced pressure at 50 ° C. for 3 hours was measured. Next, the temperature of the thermostatic bath was set to 40 ° C., the relative humidity in the bath was kept at 40%, and when the weight change of the membrane became 0.02% / 60 seconds or less, the membrane weight (D _40% (g) ) Was measured. Furthermore, the humidity in the tank was changed to 90% and maintained, and when the weight change of the film was 0.02% / 60 seconds or less, the film weight (D _90% (g)) was measured. Based on the measured value, the moisture content was determined by the following equation.

Water content [%] of relative humidity 40% = ((D _40% −D _dry ) / D _dry ) × 100
Water content [%] of relative humidity 90% = ((D _90% −D _dry ) / D _dry ) × 100

(3) Solubility in water at 20 ° C. A cast film made of an anion exchange resin having a film thickness of about 50 to 70 μm, prepared by the same method as described above, was dried under reduced pressure at 50 ° C. for 3 hours to obtain a membrane weight ( D _dry1 (g)) was measured. The membrane was then immersed in 20 ° C. water and held for 15 hours. Thereafter, the membrane was taken out of water, dried again under reduced pressure at 50 ° C. for 3 hours, and the membrane weight (D _dry2 (g)) was measured again. Based on the measured value, the solubility in water at 20 ° C. was determined by the following equation.

Solubility in water [%] = ((D _dry1 −D _dry2 ) / D _dry1 ) × 100
(4) Young's modulus (MPa) at 25 ° C. and 50% relative humidity
A measuring jig made by the same method as above and having a film thickness of about 100 μm made of an anion exchange resin is cut into a strip of 15 mm width × 70 mm length and the distance between chucks is 35 mm. Attached to. After attaching this to an autograph (AGS-500NX) equipped with a constant temperature and humidity chamber manufactured by Shimadzu Corporation, the temperature and humidity chamber was maintained at 25 ° C. and a relative humidity of 50%, and the atmosphere was stabilized for 15 minutes. The tensile test was performed at a pulling speed of 1 mm / min. From the obtained stress-strain curve, Young's modulus (MPa) was calculated.

(5) Preparation of fuel cell output (5-1) Membrane-electrode assembly (MEA) 4.3 g of a solution in which an ionic conductivity-imparting agent for anode is dissolved (concentration: 5.0% by mass, bicarbonate ion type), Platinum mixed carbon (Tanaka Kikinzoku Kogyo Co., Ltd. Fuel cell catalyst TEC10E50E, platinum content 50 mass%) 0.5g, ion-exchanged water 0.35g, 1-propanol 0.5g until mixed into a uniform paste The mixture was stirred to prepare a catalyst layer forming composition. This catalyst layer forming composition was uniformly screen-printed on the anion exchange resin membrane so that the amount of platinum deposited was 0.5 mg / cm ² and dried at room temperature for 15 hours. An anode catalyst layer was formed. In the anode catalyst layer, platinum-supported carbon / ion conductivity imparting agent = 70/30 (mass ratio), and the adhesion amount of the ion conductivity imparting agent is 0.43 mg / cm ² . Similarly, a cathode catalyst layer was formed on the back surface of the anion exchange membrane using a solution (concentration: 5.0 mass%, hydrogen carbonate ion type) in which the ion conductivity imparting agent for the cathode was dissolved (0 0.5 mg-platinum / cm ² ), MEA was obtained. The area of each catalyst layer was 5 cm ^2.

(5-2) Preparation of anion exchange membrane fuel cell The MEA obtained by the above method was immersed in a 3 mol / L aqueous sodium hydroxide solution for 30 minutes to exchange anions in the anion exchange membrane and the catalyst layer. The counter ion of the resin was exchanged with hydroxide ion, and this was thoroughly washed with ion exchange water. The MEA was sandwiched between two pieces of carbon paper (Toray Industries, Inc. TGP-H-060) and incorporated into a fuel cell conforming to a JARI (Japan Automobile Research Institute) standard cell. A carbon block provided with a serpentine type flow path was used for the battery diaphragm.

(5-3) The power generation test cell temperature was set to 60 ° C., and atmospheric pressure hydrogen (G1 grade manufactured by Taiyo Nippon Sanso Corporation) was supplied to the anode chamber at 100 ml / min (relative humidity 0% at 60 ° C.). Carbon dioxide removal at atmospheric pressure (carbon dioxide concentration of 0.1 ppm or less) is supplied to the cathode chamber at 200 ml / min (60 ° C. and relative humidity 95%), and a continuous power generation test is performed at a constant current density of 400 mA / cm ^2. went. The time point at which power generation was performed for 5 hours in advance under the above conditions was determined as the continuous operation start point, and the output at that time was defined as the initial output (mW / cm ² ). Also, the output decrease rate from the continuous operation start point and the output after 30 hours is expressed by the following formula: Output decrease rate [% / hr] = ((output of the continuous operation start point−output after 30 hours) / continuous operation start point Output x 100) / 30
And obtained as an index of output durability.

(Production Example 1)
Commercially available polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer (weight average molecular weight 70,000, styrene content 42% by weight) 40 g (containing benzene ring 161 mmol), chloroform 520 g and chloromethyl methyl ether 760 g (9. 4 mol) in a mixed solvent, and further added a solution of 35 g (134 mmol) of tin (IV) chloride in 83 g of chloroform and reacted at 35 to 40 ° C. for 2 hours in a nitrogen atmosphere. Was introduced. 200 ml of a 1: 1 mixed solution of 1,4-dioxane and water was poured into the reaction solution to stop the reaction, and then poured into 6000 ml of an aqueous methanol solution to precipitate the resin, washed several times with methanol, and then at 25 ° C. By drying for 15 hours or longer, 45.5 g of a polystyrene-poly (ethylene-propylene) -polystyrene triblock copolymer having a chloromethyl group introduced into the benzene ring as a chloromethyl group-containing resin was obtained.

  In addition, the weight average molecular weight of the triblock copolymer used as a raw material was calculated | required with the gel permeation chromatography method under the following conditions using HLC-8220GPC by Tosoh Corporation.

Column temperature: 40 ° C
Column: TSK gel SuperMultipore 2 Eluent: Tetrahydrofuran Detector: RI
Molecular weight calibration method: converted from a calibration curve prepared using polystyrene standard (TSK standard POLYSTYRENE manufactured by Tosoh Corporation) 40 g of the chloromethyl group-containing resin obtained by the above method is a mixed solution of 823 g of 30% trimethylamine aqueous solution, 594 g of acetone, and 2560 g of water. And stirred at 25 ° C. for 15 hours or longer. This resin solution was put into 2000 ml of 1 mol / L hydrochloric acid, and the anion exchange resin having a counterion of halogen ions obtained by filtration was washed twice with hydrochloric acid and then several times with ion-exchanged water. Further, it was immersed four times or more in 4 L of 0.5 mol / L sodium hydrogen carbonate aqueous solution and washed several times with ion-exchanged water. This resin was washed 5 times with 2000 ml of tetrahydrofuran, dried at 25 ° C. for 15 hours or more, and a polystyrene-poly (ethylene-propylene) -polystyrene triblock co-polymer with a quaternary ammonium base having a hydrogen carbonate ion type as a counter ion was introduced. 51.9 g of a polymer (anion exchange resin) was obtained.

45 g of the anion exchange resin obtained by the above method was put into a mixed solvent of 1217 g of tetrahydrofuran and 746 g of 1-propanol, and stirred at 25 ° C. for 24 hours to dissolve the resin. After removing suspended matters (such as filter paper fragments) contained in the solution using a centrifugal separator, the pressure was reduced to 100 hPa using a rotary evaporator, and about 1500 g of the solvent was distilled off at a temperature of 40 ° C. Thereafter, 1-propanol was added so that the weight of the solution became 746 g, the pressure was reduced to 40 hPa, and about 700 g of the solvent was distilled off at a temperature of 40 ° C. After 1-propanol was added so that the solution weight was 746 g, gas chromatographic measurement of the solution was performed, and it was confirmed that no peak derived from tetrahydrofuran was detected. As a result of measuring the solution concentration of 1-propanol solution (746 g) of the obtained anion exchange resin, the anion exchange resin concentration was 5.7% by mass. The obtained ion conductivity imparting agent solution was a uniform solution. 1-propanol (104g) was added here, and the ion conductivity-imparting agent with a solution density | concentration of 5.0 mass% was obtained (850g). The physical property values of this ion conductivity-imparting agent are shown in Table 1.
In addition, the gas chromatography measurement of the solution was measured on condition of the following using GC-14B by Shimadzu Corporation.

Column temperature: 150 ° C
Column: Sunpak-A50 C-803
Carrier gas: High purity helium 60mL / min
Detector: TCD 230 ° C., 80 mA
Sample volume: 1 μL

(Production Example 2)
In the production of the ion conductivity-imparting agent of Production Example 1, the commercially available polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer was changed to one having a weight average molecular weight of 50,000 and a styrene content of 30% by weight. Chloromethyl used for the chloromethylation reaction was changed to 768 g, chloromethyl methyl ether 548 g and tin (IV) chloride 25 g, and the mixed solvent used for dissolving the anion exchange resin was a mixture of 1000 g of tetrahydrofuran and 1000 g of 1-propanol. Except having used the solvent, operation similar to manufacture example 1 was performed and the ion conductivity-imparting agent was obtained. The physical property values of this ion conductivity-imparting agent are shown in Table 1.

(Production Example 3)
In the production of the ion conductivity-imparting agent of Production Example 1, the same operation as in Production Example 1 was carried out except that the reaction time of the chloromethylation reaction was changed to 1.2 hours to obtain an ion conductivity-imparting agent. The physical property values of this ion conductivity-imparting agent are shown in Table 1.

(Production Example 4)
In the production of the ion conductivity-imparting agent of Production Example 1, a commercially available polystyrene-poly (ethylene-propylene) -polystyrene triblock copolymer (weight average molecular weight 75,000, styrene content 65% by mass) was used. Chloroform used for the methylation reaction was changed to 450 g, chloromethyl methyl ether 1093 g, tin (IV) chloride 41 g, and the chloromethylation reaction changed to 1.2 hours, and further used for dissolving the anion exchange resin. The same operation as in Production Example 1 was carried out except that a mixed solvent of 1000 g of tetrahydrofuran and 1000 g of 1-propanol was used as a mixed solvent to obtain an ion conductivity-imparting agent. The physical property values of this ion conductivity-imparting agent are shown in Table 1.

(Reference Example 1)
In the production of the ion conductivity-imparting agent of Production Example 1, the commercially available polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer was changed to one having a weight average molecular weight of 50,000 and a styrene content of 30% by weight. Chloroform used for the chloromethylation reaction was changed to 760 g, chloromethyl methyl ether was changed to 513 g, and tin (IV) chloride was changed to 10 g, and the mixed solvent used for dissolving the anion exchange resin was a mixture of 1000 g of tetrahydrofuran and 1000 g of 1-propanol. Except having used the solvent, operation similar to manufacture example 1 was performed and the ion conductivity-imparting agent was obtained. The physical property values of this ion conductivity-imparting agent are shown in Table 1.

(Reference Example 2)
In the production of the ion conductivity-imparting agent of Production Example 1, the commercially available polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer was changed to one having a weight average molecular weight of 50,000 and a styrene content of 67% by weight. Chloromethylation used in the chloromethylation reaction was changed to 450 g, chloromethyl methyl ether to 1093 g, and tin (IV) chloride to 41 g, and the mixed solvent used for dissolving the anion exchange resin was a mixture of 1000 g of tetrahydrofuran and 1000 g of 1-propanol. Except having used the solvent, operation similar to manufacture example 1 was performed and the ion conductivity-imparting agent was obtained. The physical property values of this ion conductivity-imparting agent are shown in Table 1. The cast film prepared from this ion conductivity-imparting agent did not dissolve at 90% relative humidity, but was completely dissolved in water at 20 ° C., so the fuel cell output evaluation was not performed.

(Membrane production examples 1 to 3)
In accordance with the method described in Example 1 of WO2009-081812, an anion exchange membrane was produced in the same manner except that the properties of the porous membrane used and the composition of the polymerizable monomer composition were changed as shown in Table 2. did. The obtained anion exchange membrane was measured for film thickness, anion exchange capacity, water content, membrane resistance, and water permeability by the method described in WO2009-081812. The results are shown in Table 3.

Example 1
An anode catalyst layer was formed on the anion exchange membrane prepared in Membrane Production Example 1 using the ion conductivity imparting agent created in Production Example 1. Moreover, the cathode catalyst layer was formed using the ion conductivity-imparting agent of Reference Example 1 to prepare MEA. Using the obtained MEA, an anion exchange membrane fuel cell was prepared and a power generation test was conducted. The relative humidity at 60 ° C. of hydrogen supplied to the anode chamber was 0%, and the relative humidity at 60 ° C. of carbon dioxide-removed air supplied to the cathode chamber was 95%. The test results are shown in Table 4.

(Examples 2 to 4, Comparative Example 1)
An MEA was produced in the same manner as in Example 1 except that the ion conductivity-imparting agent used in the anode catalyst layer was changed to the ion conductivity-imparting agent shown in Table 4, and a power generation test was conducted by incorporating it into the fuel cell. The test results are shown in Table 4.

(Examples 5 and 6)
An MEA was produced in the same manner as in Example 1 except that the anion exchange membrane used in the MEA was changed to the anion exchange membrane shown in Table 4, and a power generation test was conducted in the fuel cell. The test results are shown in Table 4.

  Since Comparative Example 1 uses an ion conductivity-imparting agent having a low ion exchange capacity on the anode side as the ion conductivity-imparting agent, the water retention is low. Therefore, compared with the result of Examples 1-6, the initial output of a fuel cell is low and the output reduction rate is also large.

(Example 7)
An MEA was produced in the same manner as in Example 1 except that the ion conductivity-imparting agent used in the cathode catalyst layer was changed to the ion conductivity-imparting agent shown in Table 5, and the MEA was incorporated into a fuel cell and subjected to a power generation test. The test results are shown in Table 5.

(Examples 8 and 9, Comparative Example 2)
An MEA was produced in the same manner as in Example 1 except that the ion conductivity-imparting agent used in the cathode catalyst layer was changed to the ion conductivity-imparting agent shown in Table 5. A power generation test was performed in the same manner as in Example 1 except that the humidity of the hydrogen supplied to the anode chamber was changed to 60% relative humidity and 50% relative humidity. The test results are shown in Table 6.

1: Battery partition wall 2: Fuel gas flow hole 3: Oxidant gas flow hole 4: Fuel chamber side gas diffusion electrode (anode)
5: Oxidant chamber side gas diffusion electrode (cathode)
6: Solid polymer electrolyte 7: Fuel chamber (anode chamber)
8: Oxidant chamber (cathode chamber)
20: MEA
23: Anode catalyst layer 25: Hydrocarbon anion exchange membrane 27: Cathode catalyst layer 30: MEA
33: Anode side gas diffusion layer 34: Anode catalyst layer 35: Hydrocarbon anion exchange membrane 36: Cathode catalyst layer 37: Cathode side gas diffusion layer

Claims (11)

  Ion conductivity imparting agent used for forming an anode catalyst layer of an anion exchange membrane fuel cell, comprising an anion exchange resin having a anion exchange capacity of 1.8 to 3.5 mmol / g. Sex imparting agent.   The ion conductivity-imparting agent according to claim 1, wherein the hydrocarbon-based anion exchange resin is non-crosslinked.   The ion conductivity-imparting agent according to claim 2, wherein the non-crosslinked hydrocarbon-based anion exchange resin has a Young's modulus of 1 to 300 MPa. An anode catalyst;
The ion conductivity-imparting agent according to any one of claims 1 to 3,
An anode catalyst layer for an anion exchange membrane fuel cell comprising: A hydrocarbon-based anion exchange resin membrane;
A membrane-electrode assembly for an anion exchange membrane fuel cell, comprising a structure comprising the anode catalyst layer according to claim 4 formed on one surface of the hydrocarbon-based anion exchange resin membrane. 6. The membrane-electrode assembly according to claim 5, wherein the hydrocarbon-based anion exchange resin membrane has a water permeability of 1400 g · m ⁻² · hr ⁻¹ or more at 25 ° C.   An anion exchange membrane fuel cell comprising the membrane-electrode assembly according to claim 5.   The cathode catalyst layer of the anion exchange membrane fuel cell according to claim 7 comprises a cathode catalyst and the ion conductivity-imparting agent according to any one of claims 1 to 3. Ion exchange membrane fuel cell.   An anion exchange membrane fuel cell according to claim 7, wherein hydrogen is supplied to the anode chamber and air is supplied to the cathode chamber for power generation. how to drive.   The method for operating an anion exchange membrane fuel cell according to claim 9, wherein the hydrogen supplied to the anode chamber is hydrogen having a relative humidity of 40% or less at the operating temperature of the anion exchange membrane fuel cell.   The method for operating an anion exchange membrane fuel cell according to claim 9 or 10, wherein the air supplied to the cathode chamber is air having a relative humidity of 70% or less at the operating temperature of the anion exchange membrane fuel cell.

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