WO2017022775A1

WO2017022775A1 - Anion exchanger, ion conductivity-imparting agent, catalyst electrode layer, membrane-electrode assembly, anion exchange membrane fuel cell and anion exchange membrane water electrolysis apparatus

Info

Publication number: WO2017022775A1
Application number: PCT/JP2016/072701
Authority: WO
Inventors: 由樹吉川; 武範磯村
Original assignee: 株式会社トクヤマ
Priority date: 2015-08-04
Filing date: 2016-08-02
Publication date: 2017-02-09
Also published as: TW201716232A; JPWO2017022775A1

Abstract

[Problem] To provide an anion exchanger which is able to be used as an ion conductivity-imparting agent that is used in a fuel cell and a water electrolysis apparatus that use an anion exchange membrane, and which is capable of achieving a good balance among heat resistance, and insolubilization and ion exchange capacity increase of the ion conductivity-imparting agent. [Solution] Heat resistance is imparted by using a styrene polymer wherein the chain length of an alkyl group between an ion exchange group and an aromatic ring is extended, and a good balance between insolubilization and high ion exchange capacity is able to be achieved by using a crosslinked structure that has a quaternary ammonium group as an ion exchange group.

Description

Anion exchanger, ion conductivity imparting agent, catalyst electrode layer, membrane-electrode assembly, anion exchange membrane fuel cell, and anion exchange membrane water electrolysis device

The present invention relates to an anion exchanger having heat resistance, an ion conductivity imparting agent, and a catalyst electrode layer. The present invention also relates to a novel laminate having the catalyst electrode layer, a novel polymer electrolyte fuel cell and a water electrolysis apparatus including the laminate.

A fuel cell is a power generation system that takes out chemical energy of fuel as electric power, and several types of fuel cells such as alkaline type, phosphoric acid type, molten carbonate type, solid electrolyte type, and solid polymer type have been proposed and studied. Has been. Among these, the polymer electrolyte fuel cell is expected to be a small and medium-sized low-temperature operation fuel cell such as a stationary power source and an in-vehicle application because the operation temperature is particularly low.

The solid polymer fuel cell is a fuel cell using a solid polymer such as an ion exchange resin as an electrolyte. As shown in FIG. 1, the polymer electrolyte fuel cell is configured such that the space in the cell partition wall 1 having the fuel circulation hole 2 and the oxidant gas circulation hole 3 communicating with the outside is used as the fuel for the solid polymer electrolyte membrane 8. A joined body in which the fuel chamber side gas diffusion layer 4 and the fuel chamber side catalyst electrode layer 5 are joined to the chamber 9 side, and the oxidant chamber side catalyst electrode layer 7 and the oxidant chamber side gas diffusion layer 6 are joined to the oxidant chamber 10 side. It has a basic structure in which a fuel chamber 9 that communicates with the outside through the fuel circulation hole 2 and an oxidant chamber 10 that communicates with the outside through the oxidant gas circulation hole 3 are formed. In the polymer electrolyte fuel cell having such a basic structure, fuel made of a liquid such as hydrogen gas or alcohol is supplied to the fuel chamber 9 through the fuel flow hole 2 and the oxidant gas flow hole is supplied to the oxidant chamber 10. 3 is supplied with oxygen-containing gas such as pure oxygen or air as an oxidant, and an external load circuit is connected between the fuel chamber side catalyst electrode layer 5 and the oxidant chamber side catalyst electrode layer 7 as follows. Electric energy is generated by a simple mechanism.

As the solid polymer electrolyte membrane 8, use of an anion exchange membrane has been studied in that the reaction field becomes alkaline and a metal other than a noble metal can be used. In this case, hydrogen or alcohol or the like is supplied to the fuel chamber 9 and oxygen and water are supplied to the oxidant chamber 10, so that the catalyst contained in the electrode and the oxygen and water are contained in the oxidant chamber side catalyst electrode layer 7. To form hydroxide ions. The hydroxide ions are transferred to the fuel chamber 9 through the solid polymer electrolyte membrane 8 made of the anion exchange membrane, and react with the fuel in the fuel chamber side catalyst electrode layer 5 to generate water. become. Along with this, electrons generated in the fuel chamber side catalyst electrode layer 5 are moved to the oxidant chamber side catalyst electrode layer 7 through an external load circuit, and the energy of this reaction is used as electric energy.

In order for a polymer electrolyte fuel cell using such an anion exchange membrane to be widely used in general, it is necessary to exhibit a high output and further improve the durability. In order to obtain a high output, it is conceivable to increase the operating temperature of the polymer electrolyte fuel cell. However, when the operating temperature is increased, the deterioration of the ion exchange group of the ion conductivity-imparting agent that is the anion exchanger forming the catalyst electrode layer, and the elution of the anion exchanger from the catalyst electrode layer Peeling easily occurs. As a result, the durability of the polymer electrolyte fuel cell may be lowered.

Conventional anion exchangers are those obtained by amination and crosslinking of chloromethylated products of aromatic polyethersulfone and aromatic polythioethersulfone copolymers with polyamine (Patent Document 1), Methyl) styrene / divinylbenzene copolymer quaternized with amine (Patent Document 2), or a block copolymer having chloromethylated styrene quaternized with amine (Patent Document 3). it can. In Patent Document 1, the purpose of introducing a cross-linked structure is to reduce methanol cross leak.

Here, in these anion exchangers, focusing on the quaternary ammonium group that is the anion exchange group, in any case, the chloromethyl group is substantially aminated and introduced. The group is attached at the benzylic position relative to the aromatic ring. Generally, the benzyl position is known to be susceptible to nucleophilic attack because of its high reactivity. On the other hand, by extending the chain length of the alkyl group between the quaternary ammonium base and the aromatic ring, the reactivity of the quaternary ammonium salt can be remarkably suppressed, and the chemical stability of the exchange group can be enhanced. It is known (Patent Document 4).

Japanese Patent Laid-Open No. 11-273695 Japanese Patent Laid-Open No. 11-135137 JP 2008-226614 A Japanese Patent Laid-Open No. 04-349941

Patent Document 4 discloses a crosslinked anion exchanger excellent in heat resistance, comprising a polymer of a styrene monomer and an unsaturated hydrocarbon-containing crosslinkable monomer in which the chain length of an alkyl group between a quaternary ammonium group and an aromatic ring is extended. About. However, since it is insolubilized by introducing a crosslinkable monomer that does not contain an exchange group, there is a problem in that the ratio of ion exchange components decreases due to the introduction of a crosslinked structure.

In order to suppress the deterioration of ion exchange groups when the operating temperature of the polymer electrolyte fuel cell is increased, a crosslinked anion exchanger described in Patent Document 4 as an ion conductivity imparting agent forming a catalyst electrode layer When is used, the deterioration of the ion exchange group is suppressed. However, in order to prevent elution of the anion exchanger from the catalyst electrode layer due to a higher operating temperature, it is necessary to reduce the ratio of the ion exchange component and increase the ratio of the crosslinking component, so that the ion conductive resin is insolubilized. And high ion exchange capacity are difficult to achieve.

The inventors of the present invention have intensively studied to achieve both heat resistance and insolubilization and high exchange capacity. As a result, the use of a styrene copolymer obtained by polymerizing a styrene monomer in which the chain length of the alkyl group between the ion exchange group and the aromatic ring is increased, and the quaternary functioning as an ion exchange group. By introducing a crosslinked structure having an ammonium group, it was found that both insolubilization and high ion exchange capacity can be achieved, and the present invention has been completed.

That is, the first present invention is an anion exchanger containing a structural unit having a crosslinked structure represented by the following formula (1).

(Formula (1) represents a structural unit in which two aromatic rings are bridged, a is an integer of 3 to 10, b is an integer of 2 to 8, R ¹ , R ² , R ³ and R ⁴ Are each independently selected from a methyl group or an ethyl group, X ⁻ is one or more pairs selected from the group consisting of OH ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , Cl ⁻ , Br ⁻ and I ⁻ . Ion.)
The anion exchanger of the first aspect of the present invention exhibits excellent characteristics as an ion conductivity imparting agent, and in order to obtain excellent characteristics and durability when used in a fuel cell or a water electrolysis device, It is preferable that 70% by mass or more of the polymer is included in the structural unit having the crosslinked structure represented by 1).
The second aspect of the present invention is an ion conductivity-imparting agent comprising the anion exchanger of the first aspect of the present invention containing 70% by mass or more of the polymer having a cross-linking structure represented by the formula (1).

The third aspect of the present invention is a catalyst electrode layer containing the ion conductivity-imparting agent of the second aspect of the present invention and an electrode catalyst.

The fourth invention is a membrane-electrode assembly comprising the catalyst electrode layer of the third invention.

The fifth aspect of the present invention is an anion exchange membrane fuel cell comprising the membrane-electrode assembly of the fourth aspect of the present invention.

The sixth aspect of the present invention is a water electrolysis apparatus comprising the membrane-electrode assembly of the fourth aspect of the present invention.

The seventh aspect of the present invention provides a catalyst electrode layer-forming composition comprising a styrenic polymer having a halogenated alkyl group on an aromatic ring and an electrode catalyst, as a gas diffusion electrode, an anion exchange membrane, or a precursor of an anion exchange membrane. After applying to the body and drying to form the catalyst electrode precursor layer, the third phase is obtained by contacting with the diamine compound and performing quaternization and crosslinking reaction of the styrenic polymer having a halogenated alkyl group on the aromatic ring. It is a manufacturing method of the catalyst electrode layer characterized by forming the catalyst electrode layer as described in this invention.

The anion exchanger of the present invention provides heat resistance of the ion exchange group by using a styrenic polymer in which the chain length of the alkyl group between the ion exchange group and the aromatic ring is extended. By using a cross-linked structure having a quaternary ammonium group, the increase in the cross-linking ratio by introduction of the cross-linked structure into the anion exchanger and the high ion exchange capacity are compatible.

Further, the ion exchanger of the present invention is used as an ion conductivity-imparting agent, and a catalyst electrode layer containing the ion conductivity-imparting agent and an electrode catalyst is used as a catalyst electrode layer for an anion exchange membrane fuel cell or a water electrolysis device. By using it, it becomes possible to prevent elution of the ion conductivity-imparting agent accompanying the increase in the operating temperature of the fuel cell or water electrolysis apparatus by increasing the crosslinking ratio, and even if the crosslinking ratio is increased, Since an ion exchange group is introduced at the site, ion conductivity can be maintained high. Furthermore, the heat resistance of the anion exchange group is also improved.

It is a figure which shows an example of the structure of an anion exchange membrane type fuel cell. It is the schematic of a water electrolysis apparatus.

(Anion exchanger)
First, the anion exchanger of the present invention will be described.

The anion exchanger of the present invention can be used as an ion conductivity imparting agent for forming a catalyst electrode layer used in an anion exchange membrane fuel cell or a water electrolysis apparatus. Here, the catalyst electrode layer means both an anode to which a fuel gas such as hydrogen reacts and a cathode to which an oxidant gas such as oxygen and air reacts, and its use is not particularly limited to one electrode. It can be suitably used for the production of both anode and cathode catalyst electrode layers.

The anion exchanger of the present invention contains a structural unit having a crosslinked structure represented by the following formula (1).

(Wherein a is an integer of 3 to 10, b is an integer of 2 to 8, and R ¹ , R ² , R ³ and R ⁴ are each independently selected from a methyl group or an ethyl group. X ⁻ Is one or more counter ions selected from the group consisting of OH ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , Cl ⁻ , Br ⁻ and I ⁻ .
The structural unit represented by the formula (1) is represented by — (CH ₂ ) _a N ⁺ (X ⁻ ) R ¹ R ² (CH ₂ ) _b N ⁺ (X ⁻ ) R ³ R ⁴ (CH ₂ ) _a −. Having two groups that bridge two aromatic rings and contain two quaternary ammonium salts.

A is an integer represented by 3 to 10 and b is 2 to 8. a represents a methylene chain length for bonding an aromatic ring and a nitrogen atom of a quaternary ammonium salt adjacent thereto, and b represents a methylene chain length for bonding two quaternary ammonium salt nitrogens. When a is less than 3, chemical durability is insufficient, and when a exceeds 10, the hydrophobicity of the methylene chain increases and the anion conductivity becomes poor. a is preferably in the range of 3-6.

Since the cross-linked structure of the structural unit represented by the formula (1) contains two quaternary ammonium salts, it itself functions as an ion exchange group. -(CH ₂ ) _a N ⁺ (X ⁻ ) R ¹ R ² (CH ₂ ) _b N ⁺ (X ⁻ ) R ³ R ⁴ (CH ₂ ) _a − This is an important element for developing excellent ionic conductivity while contributing to improvement in dimensional stability and chemical durability of the ion conductivity-imparting agent. Therefore, — (CH ₂ ) _a N ⁺ (X ⁻ ) R ¹ R ² (CH ₂ ) _b N ⁺ (X ⁻ ) R ³ R ⁴ (CH ₂ ) _a − is not _a mere cross-linked site, but has ion conductivity. It needs to be designed to contribute. For methylene chain lengths that bind two quaternary ammonium bases, if too long, the hydrophobicity increases and adversely affects ionic conductivity, while if too short, the nitrogen of the two quaternary ammonium salts However, if they are too short, there is a problem. Therefore, b, which is the methylene chain length for bonding two quaternary ammonium salts, is in the range of 2 to 8, and preferably in the range of 2 to 6.

R ¹ , R ² , R ³ and R ⁴ are each independently selected from a methyl group or an ethyl group.

X ⁻ is a counter ion of a quaternary base type anion exchange group, which is a counter ion selected from OH ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , Cl ⁻ , Br ⁻ and I ⁻ , and is one kind. Alternatively, two or more counter ions may be mixed.

The anion exchanger of the present invention can be used as an ion conductivity-imparting agent for catalyst electrode layers for anion exchange membrane fuel cells and water electrolysis. When the anion exchanger of the present invention is used as an ion conductivity-imparting agent, the structural unit having a crosslinked structure represented by the formula (1) is a group having a crosslinked structure and an ion exchange group as described above. It contributes to the expression of ionic conductivity while improving the chemical stability and dimensional stability of the conductivity-imparting agent. In particular, it has been found that the durability tends to increase as the amount of the crosslinked structure introduced increases at a high temperature of 70 ° C. or higher for the operating temperature of the fuel cell or the water electrolysis apparatus. The reason for this is not yet clarified, but it is presumed that the insolubilization due to crosslinking and the increase in mechanical strength contribute to durability. In general, the higher the operating temperature, the more noticeably changes in the structure of the catalyst electrode layer due to the elution of the anion exchanger as the ion conductivity imparting agent in the catalyst electrode layer and the swelling and shrinkage of the ion conductivity imparting agent in the catalyst electrode layer. However, it is considered that elution and structural change were suppressed by the introduction of the crosslinked structure. Moreover, high battery output can be maintained even if the amount of introduction of the crosslinked structure is large due to the effect of improving the catalytic activity and the ionic conductivity by increasing the temperature. Further, the anion exchanger as the ion conductivity-imparting agent has a sufficient amount of ion conductivity around the ion exchange group due to the alkyl group between the ion exchange group and the aromatic ring in the crosslinked structure. A space where water can exist is secured, and the ionic conductivity is not impaired even if the introduction amount of the crosslinked structure is increased. Therefore, the amount of the crosslinked structure introduced into the anion exchanger of the present invention may be determined in consideration of the operating conditions of the fuel cell, the intended durability and battery output, or the operating conditions of the water electrolysis apparatus. In order to suppress the volume change due to swelling and shrinkage of the anion exchanger, the proportion of the structural unit having a crosslinked structure represented by the formula (1) is preferably 70% by mass or more of the anion exchanger, When used at a high temperature of 70 ° C. or higher, the proportion of the structural unit represented by the formula (1) is more preferably 80% by mass or more.

In the anion exchanger according to the present invention in which the content of the structural unit represented by the formula (1) is 70% by mass or more, heat resistance is imparted to the ion exchange group, and water insolubilization and high ion exchange capacity increase are achieved. compatible. Therefore, the anion exchanger can be suitably used as the ion conductivity-imparting agent of the present invention used in the catalyst electrode layer of an anion exchange membrane fuel cell or a water electrolysis device.

The anion exchanger of the present invention may be composed of any polymer as long as it contains a structural unit having a crosslinked structure represented by the formula (1). From the viewpoint of ease of polymerization, crosslinking with a diamine compound, ease of quaternization reaction, crosslinking with a diamine compound, and good physical properties after quaternization, a polymer of an aromatic vinyl compound (hereinafter referred to as “styrene-based polymer”). A polymer having a crosslinked structure represented by the formula (1) in which the ends of the alkyl group extending from the aromatic ring of the polymer are bonded with a quaternary ammonium salt type anion exchange group. preferable. In this specification, a polymer is used in the meaning including a homopolymer and a copolymer.

The anion exchanger of the present invention includes a first non-crosslinked quaternary ammonium salt type anion exchange group represented by the following formula (2) in addition to the structural unit having a crosslinked structure represented by the formula (1). (Hereinafter, also simply referred to as a first non-crosslinked structural unit).

(In the formula (2), c is an integer of 3 to 10, preferably 3 to 6, R ⁵ and R ⁶ are each independently a methyl group or an ethyl group, and R ⁷ is a straight chain having 1 to 8 carbon atoms. A chain alkyl group, X ⁻ is at least one counter ion selected from the group consisting of OH ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , Cl ⁻ , Br ⁻ and I ⁻ )
By introducing the first non-crosslinked structural unit represented by the above formula (2), the balance between hydrophilicity and hydrophobicity can be controlled, and the anion exchanger of the present invention can be used as an ion conductivity-imparting agent. When used, for example, high ionic conductivity can be maintained even when the fuel cell is operated at a low operating temperature. When the operating temperature is low, the ionic conductivity is low, but by introducing the first non-crosslinked constituent unit represented by the above formula (2), the hydrophilicity of the anion exchanger is increased and the water content is increased. The ion conductivity can be increased. In addition, when the operating temperature is low, the influence of swelling and shrinkage is small, and the durability of the catalyst electrode layer containing the ion conductivity-imparting agent is hardly lowered.

The content of the first non-crosslinked constituent unit represented by the formula (2) in the anion exchanger of the present invention is such that the operating temperature is increased when the anion exchanger is used as an ion conductivity-imparting agent. From the viewpoint of preventing the elution of the ion conductivity-imparting agent due to, preferably 0 to 20% by mass, more preferably 0 to 10% by mass.

The anion exchanger of the present invention may be copolymerized with other components as necessary within the limits that do not violate the purpose of the present invention in order to adjust the reactivity and physical properties of the anion exchanger. Good. Examples of such optional components include aromatic vinyl compounds such as styrene, α-methylstyrene, vinylnaphthalene, and acenaphthylene. The content of the structural unit derived from other components is not particularly limited, but is preferably 0 to 10% by mass, and particularly preferably 0 to 5% by mass.

The anion exchanger of the present invention may contain a second non-crosslinked quaternary ammonium base represented by the following formula (3) in addition to the structural unit having a crosslinked structure represented by the formula (1).

The anion exchanger of the present invention is obtained by crosslinking a styrene polymer having a halogenated alkyl group on an aromatic ring with a diamine compound, as will be described later. When the styrene polymer having a halogenated alkyl group on the aromatic ring and the diamine compound come into contact with each other, when the diamine compound reacts with two halogenated alkyl groups, a structural unit represented by the formula (1) is formed. However, when it reacts with only one halogenated alkyl group, a second non-bridged quaternary ammonium base of formula (3) is formed. The structural unit of the formula (3) has a quaternary ammonium base represented by — (CH ₂ ) _a N ⁺ (X ⁻ ) R ¹ R ² (CH ₂ ) _b NR ³ R ⁴ . a is an integer of 3 to 10, b is an integer of 2 to 8, and R ¹ , R ² , R ³ and R ⁴ are each independently a methyl group or an ethyl group. X ⁻ is one or more counter ions selected from the group consisting of OH ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , Cl ⁻ , Br ⁻ and I ⁻ . The preferable range of a and b is the same as that of Formula (1).

Since the structural unit having the second non-crosslinked quaternary ammonium base represented by the formula (3) has a quaternary ammonium salt structure, even if it is formed, the performance as an ion conductivity-imparting agent such as ion conductivity is improved. The impact is very small. Although the detailed reason is unknown, since the styrene polymer having a halogenated alkyl group on the non-crosslinked aromatic ring is subjected to a crosslinking reaction with a diamine compound, the amount of formula (3) produced is very small and suppressed. Of the diamine compounds involved in the reaction, the proportion of the structure of formula (3) is known to be about 10% mol even when there are many. This can be known by a generally known C ¹³ solid state NMR method or titration method.

The polymerization mode of the anion exchanger of the present invention is not particularly limited, and in the case of a copolymer, it may be a random copolymer or a block copolymer.

The number average molecular weight of the styrene polymer is preferably 5000 to 300,000, and more preferably 5000 to 200,000.

The anion exchanger of the present invention can be obtained by reacting a styrene polymer having a halogenated alkyl group with an aromatic ring containing a structural unit represented by the formula (4) and a diamine compound.

(In the formula (4), a is an integer of 3 to 10, preferably 3 to 6, and Y is any one of Cl, Br, and I.)

(Styrenic polymer having a halogenated alkyl group in the aromatic ring)
The method for synthesizing the styrenic polymer having a halogenated alkyl group in the aromatic ring is not particularly limited, but a method of polymerizing a polymerizable composition containing an aromatic vinyl compound having a halogenated alkyl group in the aromatic ring in advance, or after polymerization Examples thereof include a method of introducing a halogenated alkyl group into an aromatic ring of a styrene polymer obtained by polymerizing an aromatic vinyl compound into which a halogenated alkyl group can be introduced.

When polymerizing a polymerizable composition containing an aromatic vinyl compound having a halogenated alkyl group in the aromatic ring in advance, a polymerizable composition containing an aromatic vinyl compound having a halogenated alkyl group in the aromatic ring in advance is a known method. Polymerize. The aromatic vinyl compound having a halogenated alkyl group in the aromatic ring in advance may be polymerized alone or may be copolymerized with other aromatic vinyl compounds.

As the aromatic vinyl compound having a halogenated alkyl group in the aromatic ring in advance, those having 3 to 10 carbon atoms in the methylene chain for bonding the aromatic ring and the halogen atom are used. Preferred aromatic vinyl compounds include chloropropyl styrene, chlorobutyl styrene, chloropentyl styrene, chlorohexyl styrene, bromopropyl styrene, bromobutyl styrene, bromopentyl styrene, bromohexyl styrene, iodopropyl styrene, iodobutyl styrene, iodopentyl styrene. And haloalkylstyrene having 3 to 6 carbon atoms in the methylene chain connecting the aromatic ring and the halogen atom, such as iodohexylstyrene.

As an aromatic vinyl compound having a halogenated alkyl group in the aromatic ring in advance, chloropropyl styrene, chlorobutyl styrene, bromopropyl styrene, bromobutyl styrene may be used because of easy availability and high polymerization rate. preferable.

Other aromatic vinyl compounds include styrene, α-methylstyrene, vinyl naphthalene, acenaphthylene, vinyl pyridine, vinyl imidazole, and vinyl oxazoline.

In addition, haloalkylstyrenes having 7 or more carbon atoms in the methylene chain, which are not exemplified above, have a low polymerization rate and are likely to cause gelation during the polymerization. Since it is difficult to obtain a polymer, a styrenic polymer having a halogenated alkyl group having 7 or more carbon atoms in the methylene chain in the aromatic ring is a fragrance that can be introduced with a halogenated alkyl group after polymerization. It is preferable to synthesize by a method in which a halogenated alkyl group is introduced into an aromatic ring of a styrene polymer obtained by polymerizing an aromatic vinyl compound.

In the polymerizable composition containing an aromatic vinyl compound having a halogenated alkyl group in the aromatic ring, the content of the aromatic vinyl compound having a halogenated alkyl group in the aromatic ring is preferably from 70 to 100% by mass, and from 90 to 100%. More preferably, it is mass%.

Next, a method for introducing a halogenated alkyl group into an aromatic ring of a styrene polymer obtained by polymerizing an aromatic vinyl compound into which a halogenated alkyl group can be introduced after polymerization will be described. In this method, an aromatic vinyl compound having a structure capable of introducing a halogenated alkyl group is polymerized. After the polymerization, a halogenated alkyl group is introduced into the structure to obtain a styrene polymer having a halogenated alkyl group on the aromatic ring.

As the styrenic polymer capable of introducing a halogenated alkyl group, a polymer obtained by polymerizing styrene alone or a copolymerized with an aromatic vinyl compound other than styrene can be used. Examples of aromatic vinyl compounds other than styrene include α-methylstyrene, vinyl naphthalene, acenaphthylene, vinyl pyridine, vinyl imidazole, and vinyl oxazoline. In view of ease of polymerization, crosslinking reaction with a diamine compound, and ease of quaternization, it is preferable to use a styrene polymer obtained by polymerizing an aromatic vinyl compound alone. The method for introducing a halogenated alkyl group into the styrene polymer after polymerization is not particularly limited, and a known method may be employed. Specifically, when styrene is used as an aromatic vinyl compound into which a halogenated alkyl group can be introduced after polymerization, a method in which an aromatic ring derived from styrene is reacted with formaldehyde and then halogenated, and an aromatic ring derived from styrene is halogenated. For example, a method in which an alkyl group is given by a Grineer reaction after the formation of the alkyl chain, and the alkyl chain terminal is halogenated.

As a method for polymerizing a polymerizable composition containing an aromatic vinyl compound having a halogenated alkyl group in the aromatic ring in advance, or a polymerizable composition containing a monomer capable of introducing a halogenated alkyl group after polymerization, solution polymerization is used. Well-known polymerization methods such as suspension polymerization and emulsion polymerization are employed. The polymerization method depends on the monomer composition of the polymerizable composition and the like, and is not particularly limited and may be appropriately selected.

(Ion exchange group introduction method)
The anion exchanger of the present invention can be produced by reacting a styrene polymer having a halogenated alkyl group on the aromatic ring with a diamine compound. That is, it is represented by the formula (1) in which a halogenated alkyl group of a styrene polymer having a halogenated alkyl group on an aromatic ring reacts with a diamine compound to form a crosslinked structure by a quaternary ammonium salt type anion exchange group. The anion exchanger of the present invention containing a structural unit having a crosslinked structure can be obtained.

As the diamine compound used here, a diamine compound capable of obtaining a crosslinked structure of a structural unit having a crosslinked structure represented by the formula (1) after quaternization and crosslinking reaction may be appropriately selected.

As the alkyldiamine compound capable of obtaining a structural unit having a crosslinked structure represented by the formula (1), an alkyldiamine compound having a tertiary amine at both ends represented by the following formula (5) is preferable. Since alkyldiamine has a quaternary ammonium salt as a cross-linked structure formed after the reaction, it can contribute to improvement of ion conductivity required when the anion exchanger of the present invention is used as an ion conductivity-imparting agent.

Like b, R ¹ , R ² , R ³ and R ⁴ in formula (1), in formula (2), b indicating the length of a methylene chain connecting two nitrogen atoms is an integer of 2 to 8, A range of 2 to 6 is preferred, and R ¹ , R ² , R ³ and R ⁴ are each independently selected from a methyl group or an ethyl group.

Examples of the alkyl diamine compound used here include ethylene diamine, propane diamine, butane diamine, pentane diamine, hexane diamine, heptane diamine, and octane diamine.

Specifically, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetraethylethylenediamine, N, N-dimethyl-N ′, N′-diethylethylenediamine is used as the ethylenediamine. Examples of the propanediamine include N, N, N ′, N′-tetramethylpropanediamine, N, N, N ′, N′-tetraethylpropanediamine, N, N-dimethyl-N ′, N′-diethylpropane Examples of diamines include N, N, N ′, N′-tetramethylbutanediamine, N, N, N ′, N′-tetraethylbutanediamine, and N, N-dimethyl-N ′, N′—. Diethylbutanediamine is exemplified, and as pentanediamine, N, N, N ′, N′-tetramethylpentanediamine, N, N, N ′, N′-tetraethylpentanediamine And N, N-dimethyl-N ′, N′-diethylpentanediamine, and examples of hexanediamine include N, N, N ′, N′-tetramethylhexanediamine, N-ethylhexanediamine, N, N, N ', N'-tetraethylhexanediamine, N, N-dimethyl-N', N'-diethylhexanediamine are exemplified, and as heptanediamine, N, N, N ', N'-tetramethylheptanediamine, N, N, N ′, N′-tetraethylheptanediamine, N, N-dimethyl-N ′, N′-diethylheptanediamine are exemplified, and as octanediamine, N, N, N ′, N′-tetramethyloctanediamine, Examples thereof include N, N, N ′, N′-tetraethyloctanediamine and N, N-dimethyl-N ′, N′-diethyloctanediamine.

Among these compounds, N, N, N ′, N′-tetramethylbutanediamine is particularly preferable from the viewpoint of easy reaction, chemical durability of the crosslinked structure formed after the reaction and high ion conductivity. N, N, N ′, N′-tetramethylhexanediamine and N, N, N ′, N′-tetramethyloctanediamine can be preferably used.

The diamine compound represented by the formula (5) reacts with two halogenated alkyls of the styrenic polymer having a halogenated alkyl group on the aromatic ring to form a crosslinked structure having two quaternary ammonium salts. The following formula (6) schematically shows a reaction for forming a crosslinked structure, and two halogenated alkyls represented by (CH ₂ ) _a Y (Y is a halogen atom, and one of Cl, Br, and I) Each undergoes a quaternary ammonium salt forming reaction with a tertiary amine at the terminal of the diamine compound to form a crosslinked structure.

In the above method, the method for contacting the diamine compound and the styrene polymer having a halogenated alkyl group on the aromatic ring is not particularly limited, but the dried styrene polymer having a halogenated alkyl group on the aromatic ring is converted to the diamine. Examples thereof include a method of contacting with a compound and a method of bringing a styrenic polymer having a halogenated alkyl group into an aromatic ring into a solution and then contacting with a diamine compound in the solution. The reaction temperature is preferably 15 to 40 ° C., and the reaction time is preferably 5 to 48 hours in the former case. In the latter case, the polymer gels due to the long-time reaction. Therefore, it is preferably 30 minutes to 1 hour.

After contacting the styrene polymer having a halogenated alkyl group on the aromatic ring with the diamine compound, the excess diamine compound may be removed by a washing operation. Further, when the counter ion is a halogen ion, it can be ion-exchanged to a hydroxide ion, a bicarbonate ion, a carbonate ion or the like. The ion exchange method is not particularly limited, and a known method can be employed. After exchanging the counter ions, excess ions may be removed by washing.

(Catalyst electrode layer)
The catalyst electrode layer of the present invention comprises an ion conductivity imparting agent and an electrode catalyst comprising an anion exchanger in which the content of the structural unit represented by the formula (1) is 70% by mass or more, and an anion exchange membrane. It can be suitably used as a catalyst electrode layer of a fuel cell or water electrolysis apparatus.

An ion conductivity-imparting agent comprising an anion exchanger having a constitutional unit content represented by formula (1) of 70% by mass or more is used at a high temperature when used in a catalyst electrode layer of a fuel cell or a water electrolysis device. Even if it is operated, the ion exchange group does not deteriorate, and it does not elute into water inside the fuel cell or water electrolysis device and maintains high ionic conductivity, and has good physical properties over a long period of operation. Therefore, good fuel cell output and durability and water electrolysis performance can be realized.

In addition to the structural unit represented by the formula (1), the ion conductivity-imparting agent of the present invention includes the first non-crosslinked structural unit represented by the formula (2) and the second non-crosslinked structural unit represented by the formula (3). A structural unit of cross-linking may be included. Furthermore, in the method for producing a catalyst electrode layer in which the precursor of the catalyst electrode layer is formed on the precursor of the ion exchange membrane having an alkyl halide group, which will be described later, the catalyst is formed at the interface between the catalyst electrode layer and the ion exchange membrane. The alkyl halide group of the styrene polymer having an alkyl halide group on the aromatic ring in the precursor of the electrode layer and the precursor of the ion exchange membrane is cross-linked by a diamine, and the ion conductivity-imparting agent of the present invention is exchanged with the ion exchange membrane. It also includes a structure in which the membrane is integrated with the structural unit represented by the formula (1).

The content of the structural unit represented by the formula (1) of the ion conductivity-imparting agent of the present invention is 70% by mass or more, and the solubility in water and the volume change due to swelling shrinkage are reduced while maintaining a high ion exchange capacity. Therefore, it is preferable that it is 80 mass% or more.

Also, the ion exchange capacity of the ion conductivity-imparting agent is preferably 2.8 to 5.0 mmol / g because it can achieve excellent anion conductivity and water retention properties. The water content is preferably 10 to 100% as a value measured under the conditions of 40 ° C. and 90% RH. By having an ion exchange capacity and water content in such a range, the ion conductivity-imparting agent of the present invention dissolves in water when used in a catalyst electrode layer of a fuel cell or a water electrolysis device as described later. By doing so, it does not elute and good durability can be realized over a long operation period.

The catalyst electrode layer of the present invention contains an electrode catalyst in addition to the ion conductivity-imparting agent. A known catalyst can be used as the catalyst contained in the catalyst electrode layer. For example, platinum, gold, silver, palladium, iridium, rhodium, ruthenium, tin, iron, cobalt, nickel, molybdenum, tungsten, which promote hydrogen oxidation reaction or hydrogen generation reaction and oxygen reduction reaction or oxygen generation reaction Metal particles such as vanadium, lanthanum-based metals, or alloys thereof can be used without limitation, but a platinum group catalyst is preferably used because of its excellent catalytic activity.

The particle size of the metal particles used as the catalyst is usually 0.1 to 100 nm, more preferably 0.5 to 10 nm. The smaller the particle size, the higher the catalyst performance. However, it is difficult to produce a material having a particle size of less than 0.5 nm. These catalysts may be used after being supported on a conductive agent in advance. 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, graphite and the like are generally used alone or in combination. is there. The content of these catalysts is usually 0.01 to 10 mg / cm ² , more preferably 0.1 to 5.0 mg / cm ² in terms of metal weight per unit area when the catalyst electrode layer is in a sheet form. .

The catalyst electrode layer of the present invention may contain an electron conductivity-imparting agent for the purpose of increasing electron conductivity and obtaining excellent characteristics. Examples of the electron conductivity-imparting agent include carbon black, graphite, carbon nanotube, carbon nanohorn, and carbon fiber.

The content of the ion conductivity-imparting agent and the electrode catalyst in the catalyst electrode layer and the amount ratio thereof reflect the structure of the catalyst electrode layer and directly affect the electrochemical characteristics of the catalyst electrode layer. When the ion conductivity imparting agent is too small, the ion conductivity in the catalyst electrode layer becomes insufficient, which is not preferable. On the other hand, when the ion conductivity imparting agent is too large, the individual electrode catalyst particles are thickly coated with the ion conductivity imparting agent. As a result, the contact between the catalyst particles deteriorates and the electron conductivity becomes low, which is not preferable. Therefore, it is very important to adjust both ionic conductivity and electronic conductivity in the catalyst electrode layer to appropriate ranges. From this point of view, the mass ratio of the electrode catalyst to the ion conductivity imparting agent (mass of electrode catalyst / ion conductivity imparted) varies depending on the structure of the electrode catalyst used such as particle size and specific surface area and the structure of the ion conductivity imparting agent. The mass of the agent is preferably in the range of 99/1 to 30/70, and more preferably in the range of 95/5 to 50/50.

The catalyst electrode layer of the present invention may contain a binder as necessary. Various types of thermoplastic resins are generally used as the binder to be added as necessary. Examples of thermoplastic resins that can be suitably used include polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-par Fluoroalkyl vinyl ether copolymers, polyether ether ketones, polyether sulfones, styrene / butadiene copolymers, acrylonitrile / butadiene copolymers, and the like. When the binder is used, the content is preferably 5 to 25% by weight of the catalyst electrode layer. Moreover, a binder may be used independently and may mix and use 2 or more types.

The thickness of the catalyst electrode layer is not particularly limited, and may be appropriately determined according to the intended use. In general, the thickness is preferably 0.1 to 50 μm, more preferably 0.5 to 20 μm.

(Method for producing catalyst electrode layer)
The catalyst electrode layer of the present invention uses a composition for forming a catalyst electrode layer containing a styrene polymer having an alkyl halide group on an aromatic ring (hereinafter also referred to as an ion conductivity-imparting agent precursor) and an electrode catalyst. After applying to the diffusion layer, the anion exchange membrane, or the precursor of the anion exchange membrane and drying to form a catalyst electrode precursor layer, the ion conductivity imparting agent is brought into contact with the diamine compound in a solution containing the diamine compound. It can be produced by quaternizing and crosslinking the precursor.

According to the method for producing a catalyst electrode layer of the present invention, when the catalyst electrode layer precursor containing an ion conductivity-imparting agent precursor is subjected to quaternization and crosslinking reaction in a solution containing a diamine compound, before and after the reaction. Since the change in the dimensional change of the catalyst electrode layer itself and the internal microstructure formed in the precursor of the catalyst electrode layer can be made extremely small, it is possible to produce a catalyst electrode layer with very excellent characteristics. it can. That is, according to the method for producing a catalyst electrode layer of the present invention, the dimensional change before and after the crosslinking reaction between the ion conductivity imparting agent precursor before the reaction and the ion conductivity imparting agent obtained by the reaction. This is because the rate is very small. The reason for this is considered that the swelling of the ion conductivity-imparting agent is suppressed to a minimum because the ratio of the diamine used for the quaternization and the crosslinking reaction is high.

In general, factors affecting the characteristics of the catalyst electrode layer include electronic conductivity in the catalyst electrode layer, presence of internal pores formed by the catalyst particles and the ion conductivity imparting agent, and gas diffusivity in the ion conductivity imparting agent. The ion conductivity in the ion conductivity-imparting agent is known. The higher the electron conductivity in the catalyst electrode layer, the gas diffusibility in the ion conductivity-imparting agent, and the ion conductivity in the ion conductivity-imparting agent, the better the characteristics of the catalyst electrode layer are achieved.

In the method for producing a catalyst electrode layer, when the ion conductivity-imparting agent is greatly swollen during the crosslinking reaction, the ion conductivity was coated or contacted with the electron conductivity-imparting agent such as catalyst particles and carbon fine particles in the precursor state. When the imparting agent swells, the contact between the catalyst particles responsible for electron conduction and the electron conduction imparting agent is deteriorated, the electron conductivity is lowered, and the characteristics of the catalyst electrode layer are lowered. Furthermore, since the swelling of the ion conductivity-imparting agent closes the internal pores formed inside the catalyst electrode precursor layer, the gas diffusibility also decreases. For these reasons, when the ion conductivity-imparting agent in the catalyst electrode layer swells greatly, the characteristics of the catalyst electrode layer become insufficient.

In addition, when the swell of the ion conductivity-imparting agent is large, the dimensions of the catalyst electrode layer itself increase. That is, since the size in the state of the precursor becomes larger after the quaternization and the crosslinking reaction, a mismatch with the size of the fuel cell used for power generation tends to occur. If the area of the catalyst electrode layer is larger than the optimum size for the fuel cell to be used, in many cases, it becomes difficult to keep the inside of the cell airtight, causing gas leaks, etc., only reducing the efficiency of the fuel cell. It is even dangerous when using fuel such as hydrogen gas. Thus, the large dimensional change of the catalyst electrode layer during the crosslinking and quaternization reaction affects not only productivity but also power generation efficiency and safety.

Even when used in a water electrolysis device, the catalyst electrode layer is in direct contact with the liquid, so the effect of swelling of the ionic conductivity imparting agent due to water absorption is large, and it occurs due to catalyst dropping due to dimensional change of the catalyst electrode layer and electrode reaction. Electrolysis efficiency is significantly reduced due to the retention of gas in the catalyst electrode layer. In addition, an increase in pressure in the electrolysis cell due to gas stagnation causes gas leakage and the like, which not only lowers electrolysis efficiency, but is also dangerous because the generated gas is hydrogen gas. The large dimensional change of the catalyst electrode layer during the cross-linking and quaternization reaction as described above also affects the reduction in electrolysis efficiency and safety.

According to the present invention, not only a catalyst electrode layer having excellent characteristics is obtained, but also excellent in terms of productivity of the catalyst electrode layer, power generation efficiency of a fuel cell using the catalyst electrode layer, electrolysis efficiency of a water electrolysis apparatus, and safety. You can enjoy the effect.

Hereinafter, the manufacturing method of a catalyst electrode layer is demonstrated.
(Composition for forming catalyst electrode layer)
In forming the catalyst electrode layer, a dispersion liquid comprising an electrode catalyst, an ion conductivity-imparting agent precursor and the like can be prepared and applied to an anion exchange membrane or a gas diffusion layer. (Hereinafter, a dispersion containing an electrode catalyst and an ion conductivity-imparting agent precursor is referred to as a composition for forming a catalyst electrode layer, and a layer formed by applying this is referred to as a catalyst electrode precursor layer.)
The composition for forming a catalyst electrode layer includes an ion conductivity imparting agent precursor and an electrode catalyst, and may further include a solvent and an electron conductivity imparting agent as necessary.

The ion conductivity-imparting agent precursor is not particularly limited, and may be solid or dissolved in the catalyst electrode layer forming composition. Here, if the catalyst particles are uniformly coated with the ionic conductivity-imparting agent after the individual catalyst particles are quaternized and crosslinked, the electrochemical function of the catalyst is exhibited, and the catalyst electrode layer Highly active. Therefore, when a solvent is added to the ion conductivity-imparting agent precursor and the ion conductivity-imparting agent precursor is made into a solution, the electrode catalyst is uniformly dispersed in the dispersion, and the surface has a sufficient ion-conductivity imparting agent. By covering with a precursor, a catalyst electrode layer having excellent characteristics can be obtained.

The solvent used for the solution of the ion conductivity-imparting agent precursor is not particularly limited, but the ion conductivity-imparting agent precursor itself dissolves well, and it has good compatibility with the catalyst fine particles to obtain a high dispersion state. It is desirable to use a polar solvent. Examples of such solvents include cyclic ether organic solvents such as tetrahydrofuran and dioxane, alcohols such as methanol, ethanol, propanol and isopropyl alcohol, esters such as water and ethyl acetate, and cyclic hydrocarbons such as cyclohexane. . Moreover, you may use these mixed solvents.

The method of making the solution is not particularly limited, but a method of simply adding the ion conductivity-imparting agent precursor to the solvent and stirring it is simple. Depending on the composition and solvent composition of the ion conductivity-imparting agent precursor, dissolution is promoted by heating. The dissolution is preferably carried out at 15 ° C. or higher and below the boiling point of the solvent used.

The concentration of the ion conductivity-imparting agent precursor solution is not particularly limited. However, when the concentration of the solution is too high, the viscosity of the solution is generally extremely high, which causes a problem in handling when forming the catalyst electrode layer. In view of the fact that it takes time to form a solution, the concentration of the solution is preferably set to a relatively low concentration. The concentration of the ion conductivity-imparting agent precursor in the entire solution is 1 to 20% by mass. It is preferable that

(Catalyst for catalyst electrode layer)
The electrode catalyst used in the method for producing the catalyst electrode layer of the present invention will be described. As the catalyst for the catalyst electrode layer, a known catalyst can be used as described above. For example, metal particles such as platinum, gold, silver, palladium, iridium, rhodium, ruthenium, tin, iron, cobalt, nickel, molybdenum, tungsten, vanadium, or alloys thereof that promote hydrogen oxidation reaction and oxygen reduction reaction However, it is preferable to use a platinum group catalyst because of its excellent catalytic activity.

An electron conductivity-imparting agent may be added to the composition for the purpose of increasing the electron conductivity of the catalyst electrode layer and obtaining excellent properties. Examples of the electron conductivity-imparting agent include carbon black, graphite, carbon nanotube, carbon nanohorn, and carbon fiber.

In the composition for forming a catalyst electrode layer, the addition amount and the ratio of the ion conductivity-imparting agent precursor and the electrode catalyst greatly affect the structure of the resulting catalyst electrode precursor layer. Directly affects the electrochemical properties of If the ion conductivity imparting agent precursor is too small, the ion conductivity becomes insufficient when the catalyst electrode layer is formed, which is not preferable. On the contrary, if the amount is too large, the individual electrode catalyst particles impart ion conductivity. Since it will be thickly coated with the agent, the contact between the particles becomes poor and the electron conductivity becomes low, which is not preferable. Therefore, it is very important to adjust both ionic conductivity and electronic conductivity in the catalyst electrode layer to appropriate ranges. From this point of view, the mass ratio of electrode catalyst to ion conductivity-imparting agent precursor (mass of electrode catalyst / ion conductivity) varies depending on the structure of the electrode catalyst used, such as particle size and specific surface area, and the structure of the ion conductivity-imparting agent. The mass of the imparting agent precursor) is preferably in the range of 99/1 to 40/60, and more preferably in the range of 95/5 to 50/50.

The catalyst electrode layer forming composition of the present invention may contain a binder as necessary. Various types of thermoplastic resins are generally used as the binder to be added as necessary. Examples of thermoplastic resins that can be suitably used include polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-par Fluoroalkyl vinyl ether copolymers, polyether ether ketones, polyether sulfones, styrene / butadiene copolymers, acrylonitrile / butadiene copolymers, and the like. The content of the binder in the composition for forming a catalyst electrode layer is preferably an amount that is 5 to 25% by weight of the catalyst electrode layer. Moreover, a binder may be used independently and may mix and use 2 or more types.

The composition for forming a catalyst electrode layer is obtained by mixing at least an ion conductivity-imparting agent precursor, an electrode catalyst, and, if necessary, an electron conductivity-imparting agent in a solvent. In order to obtain a high-performance catalyst electrode layer, it is preferable that the electrode catalyst is in a highly dispersed state in the composition. Therefore, a method of obtaining a highly dispersed state of the electrode catalyst is preferably employed as a mixing method. Examples of the dispersing device include a bead mill, a ball mill, a high-pressure collision type dispersing device, an ultrasonic dispersing device, etc., and may be selected according to the aggregation state of the electrode catalyst to be used and the energy required for the dispersion, such as time and temperature. The mixing conditions may be determined in the same manner.

The viscosity of the composition for forming a catalyst electrode layer is not particularly limited as long as it is suitable for a coating method described later. The viscosity is strongly dependent on the electrode catalyst dispersion and the amount of solvent added to the composition. In general, the amount of the solvent added is determined so that the masses of the ion conductivity-imparting agent precursor and the electrode catalyst are 0.1 to 10% by mass, respectively.

(Method for forming catalyst electrode precursor layer)
In the method for producing a catalyst electrode layer in the present invention, the above-mentioned catalyst electrode layer forming composition is applied to a gas diffusion layer or an anion exchange membrane to form a catalyst electrode precursor layer and then a catalyst electrode layer. In some cases, a catalyst electrode layer is formed after coating on a precursor of an ion exchange membrane having a halogenated alkyl group to form a catalyst electrode precursor layer.

The method for applying the composition for forming a catalyst electrode layer is not particularly limited, and may be determined according to characteristics to be applied, such as a desired thickness of the catalyst electrode layer. Examples of the method include spray coating, bar coating, roll coating, gravure printing, and screen printing.

The applied catalyst electrode precursor layer is dried at an appropriate temperature. The drying conditions are not particularly limited, and may be determined according to the amount of solvent used, the boiling point, etc., as long as cracks, pinholes, etc. do not occur in the catalyst electrode precursor layer during drying. In general, drying is preferably performed at a temperature of 15 to 70 ° C. for 5 to 48 hours.

The thickness of the catalyst electrode precursor layer formed on the object to be applied is not particularly limited, and may be determined as appropriate according to the intended use. In general, the thickness is preferably 0.1 to 50 μm, and more preferably 0.5 to 20 μm.

As described above, the method for producing a catalyst electrode layer according to the present invention includes the case where the above-mentioned composition for forming a catalyst electrode layer is applied to the gas diffusion layer or the anion exchange membrane, and the case of halogenation. In some cases, a composition for forming a catalyst electrode layer is applied onto a precursor of an ion exchange membrane having an alkyl group.

First, a method for producing a catalyst electrode layer by applying a composition for forming a catalyst electrode layer on a gas diffusion layer or an anion exchange membrane will be described.

(In the case of a catalyst electrode precursor layer formed on a gas diffusion layer or an anion exchange membrane)
The catalyst electrode precursor layer formed on the gas diffusion layer or the anion exchange membrane may be quaternized and crosslinked in a solution containing a diamine compound.

About the method at the time of forming a catalyst electrode precursor layer, it does not restrict | limit by the object which apply | coats the composition for catalyst electrode layer formation, What is necessary is just to use the above-mentioned method.

Examples of the gas diffusion layer include carbon paper, carbon cloth, nickel foam, titanium foam, foamed metal, and the like, and porous graphite. In general, when used in a fuel cell, carbon paper and carbon cloth are preferably selected. In general, when used for water electrolysis, nickel foam or titanium foam is preferably selected. In addition, the gas diffusion layer is used for the purpose of facilitating the discharge of water generated by power generation outside the system when used in a fuel cell, and the purpose of suppressing the drying of the membrane-electrode assembly when using a dry gas or the like. Therefore, it may have a microporous layer composed of carbon black and a binder such as polytetrafluoroethylene, but can be used without any particular limitation in the present invention. Similarly, when used in a water electrolysis apparatus, a gas diffusion layer having a microporous layer can be used for the purpose of easily discharging hydrogen generated by electrolysis out of the system. The gas diffusion layer is not particularly limited, but is preferably a carbon porous membrane. For example, carbon fiber woven fabric, carbon paper, or the like can be used. The thickness of the gas diffusion layer is preferably 50 to 300 μm, and the porosity is preferably 50 to 90%. In the present invention, this carbon porous membrane is preferably used when the catalyst electrode layer is formed by post-crosslinking. The reason is that after the catalyst electrode precursor layer is formed, the catalyst electrode precursor layer and the diamine compound are brought into contact with each other, but the carbon porous membrane does not undergo deformation such as swelling. It is.

Further, when the catalyst electrode layer is formed on the anion exchange membrane, a known anion exchange membrane can be used without any particular limitation as the anion exchange membrane. Among these, it is preferable to use a hydrocarbon-based anion exchange membrane. Specifically, a membrane filled with an ion exchange resin into which a desired anion exchange group has been introduced by amination, alkylation or the like of a chloromethylstyrene-divinylbenzene copolymer, vinylpyridine-divinylbenzene copolymer or the like. Is mentioned. These anion exchange membranes are generally supported by a base material such as a woven fabric, a nonwoven fabric, or a porous membrane made of a thermoplastic resin, but have low gas permeability and can be thinned. Examples of the base material include a porous film made of a thermoplastic resin such as a polyolefin resin such as polyethylene, polypropylene, and polymethylpentene, and a fluorine resin such as polytetrafluoroethylene, poly (tetrafluoroethylene-hexafluoropropylene), and polyvinylidene fluoride. It is preferable to use a substrate made of Further, the film thickness of these hydrocarbon-based anion exchange membranes is preferably from 5 to 200 μm, more preferably from the viewpoint of keeping electric resistance low and imparting mechanical strength necessary as a support membrane. Has a thickness of 8 to 150 μm.

(Method of crosslinking and quaternization reaction)
Next, the catalyst electrode precursor layer formed on the gas diffusion layer or the anion exchange membrane is quaternized and crosslinked in a solution containing a diamine compound. The halogenated alkyl group of the ion conductivity-imparting agent precursor in the catalyst electrode precursor layer can be quaternized and crosslinked in a solution containing the diamine compound because the crosslinking reaction with the diamine compound proceeds easily. is there.

When the ion conductivity imparting agent precursor is quaternized and crosslinked with a diamine compound, there is a feature that the dimensional change of the ion conductivity imparting agent before and after the progress of the quaternization and crosslinking reaction can be suppressed minutely. This is because the ionic conductivity-imparting agent precursor is cross-linked with the quaternization in the solution containing the diamine compound to become an ionic conductivity-imparting agent having a cross-linked structure, thereby suppressing swelling and shrinkage. This feature expresses the function of suppressing dimensional changes in the manufacturing process of the catalyst electrode layer, and functions effectively to obtain a very high performance catalyst electrode layer.

The diamine compound used here refers to the production of the anion exchanger of the present invention described above, which can form a structural unit having a crosslinked structure represented by the formula (1) after quaternization and crosslinking reaction. What is necessary is just to select suitably the diamine compound of Formula (5) to be used.

As a method for contacting the diamine compound and the catalyst electrode precursor layer, a method suitable for manufacturing a catalyst electrode layer containing an ion conductivity-imparting agent having a crosslinked structure may be used. Specifically, a method of immersing the catalyst electrode precursor layer in a solution containing a diamine compound diluted in a solvent as necessary, a method of spraying a solution containing a diamine compound on the catalyst electrode precursor layer, and the like are included. . Among these, it is preferable to employ a method of dipping.

The amount of the diamine compound used for forming the crosslinked structure may be appropriately determined according to the diamine compound, the type of halogenated alkyl group contained in the ion conductivity-imparting agent precursor, the desired degree of crosslinking, the ion exchange capacity, and the like. Good. Specifically, when the total number of moles of halogenated alkyl groups contained in the ion conductivity-imparting agent precursor is n1, the amount of the diamine compound used is preferably 0.7 mole times or more of n1, and so on. It is preferable that it is more than mol times.

When the catalyst electrode layer of the present invention is produced by reacting the catalyst electrode precursor layer with the diamine compound, a tertiary amine is used in combination, which is an essential component of the ion conductivity-imparting agent, represented by the formula (1). In addition to the structural unit having a crosslinked structure, the first non-crosslinked structural unit represented by the following formula (2) can be introduced. By introducing the first non-crosslinked structural unit represented by the following formula (2), the balance between hydrophilicity and hydrophobicity of the catalyst electrode layer of the present invention can be controlled. When the operating temperature is low, the ionic conductivity is low, but by introducing the first non-crosslinked structural unit represented by the above formula (2), the hydrophilicity of the catalyst electrode layer is increased and the water content is increased. Ionic conductivity can be increased. In addition, when the operating temperature is low, the influence of swelling and shrinkage is small, and the durability of the catalyst electrode layer is hardly lowered. The content of the first non-crosslinked constituent unit represented by the formula (2) is preferably 0 to 20% by mass, more preferably 0, in order to prevent elution of the ion conductivity-imparting agent due to an increase in operating temperature. ~ 10% by mass.

(In the formula (2), c is an integer of 3 to 10, preferably 3 to 6, R ⁵ and R ⁶ are each independently a methyl group or an ethyl group, and R ⁷ is a straight chain having 1 to 8 carbon atoms. A chain alkyl group, X ⁻ is at least one counter ion selected from the group consisting of OH ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , Cl ⁻ , Br ⁻ and I ⁻ )

As the tertiary amine, a tertiary amine capable of obtaining a structure represented by the formula (2) after introduction may be appropriately selected. Specifically, trimethylamine, triethylamine, dimethylethylamine, dimethylpropylamine, dimethylbutylamine, dimethylpentylamine, dimethylhexylamine, dimethylheptylamine, dimethyloctylamine, diethylmethylamine, diethylpropylamine, diethylbutylamine, diethylpentylamine, Examples include diethylhexylamine, diethylheptylamine, diethyloctylamine, ethylmethylpropylamine, ethylmethylbutylamine, ethylmethylpentylamine, ethylmethylhexylamine, ethylmethylheptylamine, ethylmethyloctylamine and the like.

As the tertiary amine, it is preferable to use trimethylamine, triethylamine, dimethylbutylamine, dimethylhexylamine, dimethyloctylamine, diethylbutylamine, diethylhexylamine, diethyloctylamine for reasons of high reactivity and availability. .

When a tertiary amine is used in combination, a method of bringing the catalyst electrode precursor layer of the present invention into contact with a mixture of a diamine compound and a tertiary amine, a method in which a tertiary amine is brought into contact, and a method in which a diamine compound is brought into contact, and Any method of contacting the tertiary amine after contacting the diamine compound may be adopted.

The amount of tertiary amine used may be determined in consideration of the ratio with the diamine compound used together depending on the desired degree of crosslinking. If a large amount of monofunctional quaternizing agent (tertiary amine) reacts with the alkyl halide, as described above, the swelling of the ion conductivity-imparting agent during the post-crosslinking reaction becomes large. Since the ionic conductivity imparting agent of the invention does not exhibit the effect of suppressing swelling during the crosslinking reaction, the characteristics of the present invention are not exhibited, which is not preferable. Therefore, when the tertiary amine and the diamine compound are used simultaneously or stepwise, the tertiary involved in the reaction with respect to 1 mole of the alkyl halide group of the ion conductivity-imparting agent contained in the catalyst electrode precursor layer. The amine is preferably 0.3 mol or less, and more preferably 0.2 mol or less. Moreover, it is preferable that it is 0.01 mol or more.

However, the total amount of the diamine compound and the tertiary amine used as required may be equal to or greater than the equivalent mole of the halogenated alkyl group of the ion conductivity-imparting agent precursor. preferable.

Further, the solution containing the diamine compound may contain a solvent. However, when a tertiary amine is not used, that is, when a diamine compound alone is used in the reaction, it is preferable not to use a solvent because the diamine concentration during the reaction does not change and does not affect the reaction rate.

The solvent to be used can be selected without particular limitation as long as the components of the catalyst electrode precursor layer are not dissolved, and water, alcohols such as methanol, ethanol and propanol, ketones such as acetone and the like are preferably used.

The reaction temperature is preferably 15 to 40 ° C., the reaction time is preferably 5 to 48 hours, and more preferably 5 to 24 hours from the viewpoint of increasing productivity.

After contacting the catalyst electrode precursor layer and the diamine compound, the excess diamine compound may be removed by a washing operation.

Furthermore, when the counter ion is a halogen ion, it can be ion-exchanged to a hydroxide ion, a bicarbonate ion, a carbonate ion, or the like. The ion exchange method is not particularly limited, and a known method can be employed. After exchanging the counter ions, excess ions may be removed by washing.

Next, a method for producing the catalyst electrode layer formed on the precursor of the ion exchange membrane will be described.

(In the case of the catalyst electrode precursor layer formed on the anion exchange membrane precursor)
In the present invention, a catalyst electrode precursor layer is formed on an ion exchange membrane precursor having a halogenated alkyl group, and the catalyst electrode layer is formed by performing quaternization and a crosslinking reaction in a solution containing a diamine compound. You can also

In the above production method, not only the halogenated alkyl groups of the ion conductivity imparting agent precursor in the catalyst electrode precursor layer but also the alkyl halide possessed by the ion conductivity imparting agent precursor contained in the catalyst electrode precursor layer. Since a crosslinking reaction is caused by the diamine even between the group and the halogenated alkyl group of the ion exchange membrane precursor, a membrane-electrode assembly in which the catalyst electrode layer and the anion exchange membrane are crosslinked is obtained.

The precursor of an anion exchange membrane having a halogenated alkyl group means a precursor of an ion exchange membrane having a functional group into which an ion exchange group can be introduced, which is produced by a known method for producing an anion exchange membrane. . Examples include precursors of hydrocarbon-based anion exchange membranes, and specific examples include membranes filled with chloromethylstyrene-divinylbenzene copolymer, bromobutylstyrene-divinylbenzene copolymer, and the like. The copolymers contained in the precursors of these anion exchange membranes are generally supported by a base material such as a woven fabric, a nonwoven fabric, or a porous membrane made of a thermoplastic resin, but the gas permeability is low. Since the substrate can be thinned, the base material includes polyolefin resins such as polyoctane, polypropylene and polymethylpentene, and fluorine-based resins such as polytetrafluorooctane, poly (tetrafluorooctanehexafluoropropylene) and polyvinylidene fluoride. It is preferable to use a base material made of a porous film made of a thermoplastic resin such as. Further, the film thickness of these hydrocarbon-based anion exchange membranes is preferably from 5 to 200 μm, more preferably from the viewpoint of keeping electric resistance low and imparting mechanical strength necessary as a support membrane. Has a thickness of 8 to 150 μm.

In the present invention, the quaternization and crosslinking reaction of the catalyst electrode precursor layer formed on the anion exchange membrane precursor is performed by the above-described gas diffusion layer or catalyst electrode precursor layer formed on the anion exchange membrane. The quaternization and crosslinking reaction are preferably performed under the same conditions.

(Membrane-electrode assembly)
The membrane-electrode assembly formed by laminating the catalyst electrode layer and the anion exchange membrane of the present invention can be suitably used for an anion exchange membrane fuel cell and a water electrolysis apparatus. As described above, in the membrane-electrode assembly of the present invention, the composition for forming a catalyst electrode layer containing an ion conductivity-imparting agent precursor and a catalyst is placed on the anion exchange membrane or the precursor of the anion exchange membrane. It can be obtained by coating, drying, forming a catalyst electrode precursor layer, contacting with a diamine compound, and performing a quaternization and a crosslinking reaction.

Further, the gas diffusion electrode formed by laminating the catalyst electrode layer and the gas diffusion layer of the present invention can be suitably used for an anion exchange membrane fuel cell and a water electrolysis device. As described above, the gas diffusion electrode of the present invention forms a catalyst electrode precursor layer by applying a catalyst electrode layer forming composition containing an ion conductivity-imparting agent precursor and a catalyst onto the gas diffusion layer and drying it. It can be obtained by contacting with a diamine compound to carry out a quaternization and a crosslinking reaction.

(Anion exchange membrane fuel cell)
If the gas diffusion electrode or the membrane-electrode assembly described above is used, an anion exchange membrane fuel cell can be assembled with the configuration shown in FIG. 1, for example. That is, when the catalyst electrode layer is formed on the gas diffusion layer, two of them are used to sandwich the anion exchange membrane on the side where the catalyst electrode layer is formed. Thereby, the state where 4, 5, 6, 7, and 8 in FIG. 1 are combined can be realized. Alternatively, when the catalyst electrode layer precursor is directly formed on both sides of the anion exchange membrane or its precursor and the catalyst electrode layer is formed after crosslinking and quaternization, it can be used as a fuel cell as it is. it can. In addition, a fuel cell can be configured by stacking a support (carbon porous membrane) functioning as a gas diffusion layer on the catalyst electrode layer in order to improve gas diffusibility.

The above-described anion exchange membrane fuel cell can generate electric power by supplying humidified hydrogen gas to the fuel chamber side and humidified oxygen or air to the oxidizer chamber side when hydrogen is used as the fuel.

In the anion exchange membrane fuel cell of the present invention, the heat resistance of the anion exchange group is improved, and further, the elution of the ion conductivity imparting agent from the catalyst electrode layer accompanying the increase in the operating temperature is prevented and the ion Since conductivity can be maintained high, it is possible to maintain good power generation performance of the fuel cell over a long period of time.

(Water electrolysis device)
Further, if the gas diffusion electrode or the membrane-electrode assembly described above is used, a water electrolysis apparatus can be assembled. That is, when the catalyst electrode layer is formed on the gas diffusion layer and the gas diffusion electrode is formed after cross-linking and quaternization, the one in which both sides of the anion exchange membrane are sandwiched between the gas diffusion electrodes is used as the water electrolysis apparatus. Can be used. Alternatively, if the catalyst electrode layer precursor is formed directly on both sides of the anion exchange membrane or its precursor and the catalyst electrode layer is formed after crosslinking and quaternization, it should be used as it is as a water electrolysis device. Can do. Further, a water electrolysis apparatus is configured by stacking a support (carbon porous body or metal porous body) functioning as a gas diffusion layer on the catalyst electrode layer in order to improve gas diffusibility. be able to.

FIG. 2 shows a simple configuration example of such a water electrolysis apparatus, but the water electrolysis apparatus of the present invention is not limited to the structure of FIG. In FIG. 2, the example of the water electrolysis apparatus 20 using the anion exchange membrane 8 was shown. A cathode side catalyst electrode layer 11 is provided on one side of the anion exchange membrane 8, and an anode side catalyst electrode layer 12 is provided on the other side. Although a gas diffusion layer may be provided on the surface of each catalyst electrode layer, it is omitted in this figure. At least one of the cathode side catalyst electrode layer 11 and the anode side catalyst electrode layer 12 may be the catalyst electrode layer of the present invention, but preferably both are formed of the catalyst electrode layer of the present invention. Each catalyst electrode layer is connected to an external power source 30 via

conductors

31 and 32, respectively. The electrolytic cell is provided with raw water supply pipes 13 and 14 for supplying raw water. As the raw water, a dilute alkaline aqueous solution is preferably used from the viewpoint of electrolysis efficiency, and for example, a dilute aqueous solution of KOH is used. By supplying raw water and energizing from an external power source, water electrolysis starts. The reaction on the cathode side and the anode side is as follows.

(Cathode side) 2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻
(Anode side) 2OH ⁻ → 1 / 2O ₂ + H ₂ O + 2e ⁻

On the cathode side, hydrogen and hydroxide ions are generated by electrolysis of water. The hydroxide ions reach the anode side through the laminated ion exchange membrane 8, and generate oxygen, water, and electrons. Hydrogen generated on the cathode side is recovered through the gas recovery tube 15, and oxygen generated on the anode side is recovered through the gas recovery tube 16.

In the water electrolysis apparatus of the present invention, the heat resistance of the anion exchange group is improved, and further, the elution of the ion conductivity-imparting agent from the catalyst electrode layer accompanying the increase in the operating temperature is prevented and the ion conductivity is increased. Therefore, it is possible to maintain the operation with high electrolytic efficiency over a long period of time.

Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to these examples. In addition, the characteristic of the anion exchanger shown in an Example and a comparative example and a fuel cell shows the value measured with the following method.

(Ion exchange capacity of anion exchanger)
A solution (concentration 5.0 mass%, solution amount 2.5 g) in which the precursor of the styrene ion exchanger before the quaternization / crosslinking reaction was dissolved was cast on a Petri-tetrafluoroethylene petri dish, Produced. The cast film was reacted with a solution containing diamine to introduce ion exchange groups. The anion exchanger cast film thus obtained was thoroughly washed with ion-exchanged water, and then packed in a Vyskin tube together with ion-exchanged water, and both ends were tied up. The Visking tube was made of cellulose, the molecular weight cut off was 8,000, and the mass (Dv (g)) after drying under reduced pressure at 50 ° C. for 3 hours was measured in advance. The operation of immersing the Visking tube containing the cast film in a 0.5 mol / L-HCl aqueous solution (50 mL) for 30 minutes was repeated three times, and the cast film inside was made a chloride ion type. Furthermore, it was immersed in ion exchange water (50 mL) for 10 minutes and washed (10 times). This was immersed in a 0.2 mol / L-NaNO ₃ aqueous solution (50 mL) for 30 minutes or more, substituted with a nitrate ion type, and extracted free chloride ions (four times). Further, chloride ions extracted by immersion 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 was immersed in a 0.5 mol / L-NaCl aqueous solution (50 g) for 30 minutes or more (three times), and sufficiently dialyzed with ion-exchanged water until chloride ions were not detected in the washing solution. Thereafter, the tube was taken out, held in a dryer at 50 ° C. for 15 hours to remove moisture in the tube, and then dried under reduced pressure at 50 ° C. for 3 hours to measure its mass (Dt (g)). Based on the measured value, the ion exchange capacity was determined by the following equation.
Ion exchange capacity = A × 1000 / (Dt−Dv) [mmol / g−dry mass]

(Method for determining the content of the structural unit having a crosslinked structure represented by formula (1) in the anion exchanger)
First, in the case of crosslinking and quaternization only with a diamine compound, the amount of the structural unit represented by the formula (1) contained in the anion exchanger can be quantified by solid NMR.

From the ¹ H-NMR spectrum obtained from the cast film prepared using only the diamine compound, the peak area of the structural unit represented by formula (1), the peak area of the structural unit represented by formula (3), and the structure represented by formula (4) Each ratio of the peak area of the unit was obtained, and the content rate of the formula (1) was calculated from the abundance ratio of each structural unit. The content of the obtained formula (1) is also shown in Table 1.

When a diamine compound and a tertiary amine are used in combination, a tertiary amine containing a ¹³ C isotope in the molecule can be used, and the amount of the tertiary amine contained by the ¹³ C-NMR spectrum can be quantified.

The peak area of the ¹³ C-NMR spectrum of trimethylamine obtained from a cast film prepared using only trimethylamine ( ¹³ C isotope) was set to 1, and the mixture was crosslinked with a mixed solution of diamine compound and trimethylamine mixed at an arbitrary ratio. The ratio of the peak area obtained when the graded cast film was measured with a ¹³ C-NMR spectrum to the peak area of trimethylamine was P, and the degree of crosslinking = 1-P was calculated ( ¹³ C derived from other carbon atoms). Is 0 because it is a very small amount). Based on the obtained degree of crosslinking, the content of formula (1) was determined from the following formula.
Content = crosslinking degree × molecular weight of formula (1) / [crosslinking degree × molecular weight of formula (1) + P × molecular weight of formula (2)]
The content of the structure of the obtained formula (1) is also shown in Table 1.

(Heat resistance of anion exchanger)
Prepare two anion exchangers in a polytetrafluoroethylene container after converting the counter ion to hydroxide ion type, in an oven at 50 ° C or 90 ° C for 500 hours in ion-exchanged water, respectively. After holding, each anion exchange capacity was measured. The anion exchange capacity retention was determined from the ratio of the anion exchange capacity of the anion exchanger after treatment to the anion exchange capacity of the anion exchanger before treatment, and evaluated as the heat resistance of the anion exchange group.

(Measurement method of moisture content of anion exchanger)
A measuring device (“MSB-AD-V-FC”, manufactured by Nippon Bell Co., Ltd.) comprising a cast film having a film thickness of about 50 to 70 μm produced by the same method as described above and having a thermo-hygrostat equipped with a magnetic floating balance. )). First, the film mass (Ddry (g)) after drying under reduced pressure at 50 ° C. for 3 hours was measured. Next, the temperature of the thermostatic bath is set to 40 ° C., the relative humidity in the bath is maintained at 90%, and when the mass change of the membrane becomes 0.02% / 60 seconds or less, the membrane mass (D (g)) is set. It was measured. Based on the measured value, the moisture content was determined by the following equation.
Water content at 90% relative humidity = ((D−Ddry) / Ddry) × 100 [%]

(Method for measuring solubility in water)
10 g of the anion exchanger was immersed in 100 ml of ion exchange water at 80 ° C. for 1 hour with stirring using a magnetic stirrer, and the undissolved anion exchanger was removed from the ion exchange water by vacuum filtration. The remaining ion-exchanged water was put into an eggplant-shaped flask and concentrated under reduced pressure, followed by vacuum drying at 50 ° C. for 3 hours, and the weight of the residue was measured. Based on the above measured value, the weight% of the anion exchanger dissolved in water was calculated, and if the value was 0.5% by weight or less, the water resistance was evaluated as good.

(Fuel cell assembly method)
When the catalyst electrode layer is formed on the gas diffusion layer and the gas diffusion electrode is formed, the gas diffusion electrode cut into 23 mm square (about 5 cm ² ) is converted into an ion exchange membrane (anion exchange capacity of 1.8 mmol). / G-dry mass, water content at 25 ° C. is 25% by mass, dry film thickness is 28 μm, outer dimension 40 mm square), and the gas diffusion electrode catalyst electrode layers are placed one by one, The fuel cell shown in FIG. 1 was incorporated. When the catalyst electrode layer is formed on an ion exchange membrane or a precursor thereof, that is, when a membrane-electrode assembly is formed, a gas diffusion layer (Toray Industries, Inc.) cut into 23 mm square (about 5 cm ² ) Two sheets of HGP-H-060 (thickness: 200 μm) were used and laminated one by one on the catalyst electrode layers on both sides of the membrane-electrode assembly, and assembled into the fuel cell shown in FIG.

(Power generation durability test method)
As fuel gas, 100 ml / min of hydrogen humidified to 90% RH with respect to the cell temperature and 200 ml / min of air humidified to 90% RH with respect to the cell temperature as oxidant gas were supplied to the fuel cell. The temperature of the fuel cell was 50 ° C. or 90 ° C. The cell voltage value (V) when a current of 500 mAcm ⁻² was taken out from this cell was measured. Moreover, the voltage value after 100 hours in this state was measured.

Example 1
30 g of bromobutylstyrene was subjected to radical polymerization with 2,2′azobisisobutyronitrile in a toluene solvent to obtain polybromobutylstyrene (number average molecular weight 80,000). A cast film of the obtained polybromobutylstyrene was prepared and immersed in 50 g of a diamine compound (N, N, N ′, N′-tetramethyl-1,6-hexanediamine). The cast film of the anion exchanger was obtained by taking out after 24 hours, and wash | cleaning.

Table 1 shows the content, the solubility test result, the heat resistance test result, the ion exchange capacity, and the moisture content of the structural unit having the crosslinked structure represented by the formula (1) of the cast film of the obtained anion exchanger. .

Next, polybromobutylstyrene was dissolved in ethyl acetate to prepare a 5 wt% solution. To 2 g of this solution, 1 g of a catalyst (a carbon particle having a primary particle size of 30 to 50 nm and platinum particles having a particle size of 2 to 10 nm supported) was added and dispersed to prepare a composition for forming a catalyst electrode layer. This was applied on a gas diffusion layer (carbon paper manufactured by SGL Carbon, GDL25BC, thickness 190 μm) in a size of 23 mm square (about 5 cm ² ) so that platinum would be 0.5 mgcm ⁻² , dried, and then dried. A catalyst electrode precursor layer was obtained on the diffusion layer. The catalyst electrode precursor layer was immersed in 20 g of a diamine compound (N, N, N ′, N′-tetramethyl-1,6-hexanediamine). The gas diffusion electrode was obtained by removing after 24 hours and washing. The obtained gas diffusion electrode was immersed in a 1 mol / L potassium bicarbonate aqueous solution 5 times for 15 minutes, exchanged counter ions with bicarbonate ions, washed with ion exchange water, and then dried at room temperature for 24 hours. I let you. In the gas diffusion electrode after drying, the thickness of the catalyst electrode layer was 5 μm. A power generation durability test was performed using the obtained gas diffusion electrode. The results are shown in Table 2.

Example 2
The same as in Example 1 except that a solution having a molar ratio of 2: 8 of trimethylamine and N, N, N ′, N′-tetramethyl-1,6-hexanediamine was used as a reagent for quaternization / crosslinking reaction. The operation was carried out to prepare an anion exchanger cast film and a gas diffusion electrode. Table 1 shows the content, the solubility test result, the ion exchange capacity, and the water content of the structural unit having the crosslinked structure represented by the formula (1) of the cast film of the obtained anion exchanger. In addition, a power generation durability test was performed using the obtained gas diffusion electrode. The results are shown in Table 2.

Example 3
An anion exchanger cast film and a gas diffusion electrode were prepared in the same manner as in Example 1 except that polybromopropylstyrene was used instead of polybromobutylstyrene. Table 1 shows the content, the solubility test result, the heat resistance test result, the ion exchange capacity, and the moisture content of the structural unit having the crosslinked structure represented by the formula (1) of the cast film of the obtained anion exchanger. . In addition, a power generation durability test was performed using the obtained gas diffusion electrode. The results are shown in Table 2.

Comparative Example 1
An anion exchanger cast film and a gas diffusion electrode were prepared in the same manner as in Example 1 except that commercially available polychloromethylstyrene (number average molecular weight 55,000) was used instead of polybromobutylstyrene. . Table 1 shows the solubility test results, ion exchange capacity, and moisture content of the cast film of the obtained anion exchanger. In addition, a power generation durability test was performed using the obtained gas diffusion electrode. The results are shown in Table 2.

Comparative Example 2
An anion exchanger cast film and a gas diffusion electrode were prepared in the same manner as in Example 2 except that commercially available polychloromethylstyrene was used instead of polybromobutylstyrene. Table 1 shows the solubility test results, heat resistance test results, ion exchange capacity and water content of the cast film of the obtained anion exchanger. In addition, a power generation durability test was performed using the obtained gas diffusion electrode. The results are shown in Table 2.

Comparative Example 3
Crosslink by adding 1.75 parts by weight of divinylbenzene (purity 57%) and 1.0 part by weight of azobisbutyronitrile to 98.25 parts by weight of bromobutylstyrene and maintaining at 70 ° C. for 24 hours in a nitrogen atmosphere. A polymer was obtained. The obtained crosslinked polymer was suspended in dioxane, then, 3 molar equivalents of trimethylamine with respect to the bromo group were added dropwise, and the suspension was reacted at 50 ° C. for 10 hours. The resulting quaternized crosslinked polymer was washed thoroughly with ion exchange water. The resulting quaternized crosslinked polymer was subjected to solubility test results, heat resistance test results, ion exchange capacity measurement, and moisture content measurement. The results are shown in Table 1. Further, the obtained quaternized crosslinked polymer and Pt / C catalyst were dispersed in a propanol solvent to prepare a composition for forming a catalyst electrode layer. This was applied onto the gas diffusion layer and then dried to obtain a gas diffusion electrode. A power generation durability test was performed using the obtained gas diffusion electrode. The results are shown in Table 2.

Comparative Example 4
The same operation as in Comparative Example 3 was performed except that 17.5 parts by weight of divinylbenzene (purity 57%) and 1.0 part by weight of azobisbutyronitrile were added to 82.5 parts by weight of bromobutylstyrene to prepare a crosslinked polymer. And a quaternized crosslinked polymer and a gas diffusion electrode were prepared. Table 1 shows the solubility test results, heat resistance test results, ion exchange capacity and water content of the resulting quaternized crosslinked polymer. In addition, a power generation durability test was performed using the obtained gas diffusion electrode. The results are shown in Table 2.
In addition, the divinylbenzene crosslinking degree in a table | surface is the ratio (weight%) of divinylbenzene to the total monomer weight in a preparation stage.

From the results of Examples 1 to 3, the following was confirmed.

First, a styrenic polymer in which the chain length of the alkyl group between the ion exchange group and the aromatic ring is extended is quaternized and crosslinked in a solution containing the diamine compound, so that the crosslinked structure is crosslinked with the diamine compound. It was confirmed that it is possible to form a catalyst electrode layer containing an ion conductivity-imparting agent having an excellent fuel cell output characteristic.

As in Comparative Example 1, when polystyrene having a short chain length of the alkyl group between the ion exchange group and the aromatic ring was used, as can be seen from the results of the ion exchange capacity and water content, Quaternization hardly proceeds, and it becomes very hydrophobic and shows low ionic conductivity. As a result, the fuel cell output characteristics are very limited. Moreover, as a result of the physical property evaluation of the cast film, the dispersion state of the ion conductivity-imparting agent precursor in the catalyst electrode layer is poor, and when the ion conductivity-imparting agent precursor is solidified, the crosslinking reaction proceeds. This means that the ionic conductivity is not expressed. The results of Example 1 and Comparative Example 1 show that the styrenic polymer in which the chain length of the alkyl group between the ion exchange group and the aromatic ring is extended has a poor resin dispersibility when the catalyst electrode layer is produced. This also suggests that it has sufficient ionic conductivity to exhibit good battery characteristics. Further, in Comparative Example 1, since the alkyl chain length between the ion exchange group and the aromatic ring is short, the heat resistance of the ion exchanger is low, and the operating temperature is 90 ° C. compared to the case where the operating temperature of the fuel cell is 50 ° C. The power generation durability is low.

As in Comparative Example 2, when polystyrene having a short chain length of the alkyl group between the ion exchange group and the aromatic ring is used, by using a tertiary amine and a diamine compound in combination, crosslinking and quaternization to some extent are possible. The heat resistance of the anion exchanger at 50 ° C. and the results of the power generation test are relatively good. However, since the alkyl chain length between the ion exchange group and the aromatic ring is short, the heat resistance and power generation test results of the anion exchanger at 90 ° C. are low values.

In the case of the crosslinking having no ion exchange ability at the crosslinking site as in Comparative Examples 3 and 4, in Comparative Example 3 having a low degree of crosslinking, the solubility of the ion conductivity-imparting agent in water increases, and the ion conductivity-imparting agent With the elution of the catalyst, the performance of the catalyst electrode layer decreases, and the fuel cell output characteristics are limited. Increasing the degree of crosslinking as in Comparative Example 4 improves the solubility of the ion conductivity-imparting agent in water, but the performance of the catalyst electrode layer decreases due to a decrease in ion conductivity due to an increased crosslinking ratio. However, the voltage value at the initial stage of power generation is low, and the fuel cell output characteristics are limited. In addition, in the durability test of the anion exchanger, good results were obtained even at 90 ° C., but in the power generation test at 90 ° C., the voltage after 100 hours decreased, Under the immersed condition, the effect of high heat resistance can be obtained by extending the alkyl chain length between the exchange group and the aromatic ring. However, under the power generation condition, drying proceeds by adding a hydrophobic cross-linking site, and heat is generated. It was confirmed that the decomposition reaction was promoted.

When forming a catalyst electrode layer using the anion exchanger of the present invention, it has high heat resistance, and by introducing a cross-linked structure with a diamine compound and imparting ion exchange capacity, excellent performance and excellent catalyst electrode layer performance The fuel cell output characteristics can be obtained.

DESCRIPTION OF SYMBOLS 1; Battery partition 2; Fuel flow hole 3; Oxidant gas flow hole 4; Fuel chamber side gas diffusion layer 5; Fuel chamber side catalyst electrode layer 6; Oxidant chamber side gas diffusion layer 7; 8; Solid polymer electrolyte membrane (anion exchange membrane)
9; Fuel chamber 10; Oxidant chamber 11; Cathode side catalyst electrode layer 12; Anode side catalyst electrode layers 13 and 14; Raw

water supply pipes

15 and 16; Gas recovery pipe 20;

Claims

A structural unit having a crosslinked structure represented by the following formula (1)

(Wherein a is an integer of 3 to 10, b is an integer of 2 to 8, and R 1 , R 2 , R 3 and R 4 are each independently selected from a methyl group or an ethyl group. X − Is one or more counter ions selected from the group consisting of OH − , HCO 3 − , CO 3 2− , Cl − , Br − and I − ).
The anion exchanger according to claim 1, wherein the content of the structural unit represented by the formula (1) is 70% by mass or more.
An ion conductivity-imparting agent comprising the anion exchanger according to claim 2.
A catalyst electrode layer containing the ion conductivity-imparting agent according to claim 3 and an electrode catalyst.
A membrane-electrode assembly comprising the catalyst electrode layer according to claim 4.
An anion exchange membrane fuel cell comprising the membrane-electrode assembly according to claim 5.
A water electrolysis apparatus comprising the membrane-electrode assembly according to claim 5.
A composition for forming a catalyst electrode layer containing a styrenic polymer having an alkyl halide group on an aromatic ring and an electrode catalyst is applied to a gas diffusion layer, an anion exchange membrane, or a precursor of an anion exchange membrane, and dried. After forming the catalyst electrode precursor layer, the catalyst electrode layer according to claim 4 is subjected to quaternization and crosslinking reaction of a styrene polymer having a halogenated alkyl group on an aromatic ring by contacting with a diamine compound. A method for producing a catalyst electrode layer, comprising: forming a catalyst electrode layer.