WO2012017965A1

WO2012017965A1 - Aromatic copolymer with sulfonic acid groups and uses thereof

Info

Publication number: WO2012017965A1
Application number: PCT/JP2011/067525
Authority: WO
Inventors: 芳孝山川; 敏明門田; 拓也村上; ロジャンスキー　イーゴリ
Original assignee: Jsr株式会社
Priority date: 2010-08-03
Filing date: 2011-07-29
Publication date: 2012-02-09
Also published as: JPWO2012017965A1

Abstract

Provided is an aromatic copolymer with sulfonic acid groups that has high proton conductivity, low swelling in hot water and low shrinkage during drying. The aromatic copolymer comprises polymer segments (A) containing structural units represented by formula (1) and polymer segments (B) containing structural units represented by formula (4). (1) (4) (In formula (1), each R¹ independently represents a halogen atom, a C_1-20 monovalent hydrocarbon group, or a C_1-20 monovalent halogenated hydrocarbon group; a represents an integer of 0 to 3; and k represents an integer 1 to 4 with a+k being an integer of 4 or less. The multiple R¹s can be the same or different.) (In formula (4), each E independently represents at least one structure selected from the group consisting of -CO-, -SO₂-, -SO-, -CONH-, and -COO- groups; and Ar³¹, Ar³² and Ar³³ each independently represent divalent or trivalent organic groups having benzene rings, naphthalene rings or nitrogen-containing heterocyclic rings or said organic groups wherein some or all of the hydrogen atoms have been substituted with fluorine atoms. R³¹ represents at least one structure selected from the group consisting of direct bonds, -O(CH₂)_p-, -O(CF₂)_p-, -(CH₂)_p-, and -(CF₂)_p- (p represents an integer of 1 to 12). e represents an integer of 0 to 10, f represents an integer of 1 to 5 and g represents an integer of 0 to 4.)

Description

Aromatic copolymer having sulfonic acid group and use thereof

The present invention relates to an aromatic copolymer having a novel sulfonic acid group, a solid polymer electrolyte comprising the aromatic copolymer having the sulfonic acid group, and use thereof.

Electrolytes are usually used in an aqueous solution. However, in recent years, there is an increasing tendency to replace the electrolyte with a solid system. The first reason is, for example, the ease of processing when applied to electrical / electronic materials, and the second reason is the shift to light, thin, small, and power saving.

Conventionally, both inorganic compounds and organic compounds are known as proton conductive materials. Examples of inorganic compounds include uranyl phosphate, which is a hydrated compound. However, since these inorganic compounds do not have sufficient contact at the interface with the substrate or electrode, a conductive layer is formed on the substrate or electrode. Many problems arise.

On the other hand, examples of organic compounds include sulfonated products of vinyl polymers such as polystyrene sulfonic acid, perfluoroalkyl sulfonic acid polymers represented by Nafion (trade name, manufactured by DuPont), and perfluoroalkyl carboxylic acid polymers. Examples include polymers belonging to so-called cation exchange resins, or organic polymers such as polymers in which a sulfonic acid group or a phosphoric acid group is introduced into a heat-resistant polymer such as polybenzimidazole or polyether ether ketone.

When producing a fuel cell, an electrode-membrane assembly is usually obtained by sandwiching an electrolyte membrane made of the perfluoroalkylsulfonic acid polymer between both electrodes and performing a heat treatment such as hot pressing. A fluorine-based film such as this perfluoroalkyl sulfonic acid polymer has a relatively low heat deformation temperature of about 80 ° C., and can be easily joined. However, at the time of fuel cell power generation, the temperature may be 80 ° C. or higher due to the reaction heat, so that the electrolyte membrane softens and a creep phenomenon occurs, which causes a problem that both electrodes are short-circuited and power generation becomes impossible.

In order to avoid such problems, currently the fuel cell is designed so that the thickness of the electrolyte membrane is increased to some extent or the temperature during power generation is 80 ° C. or less, but the maximum output of power generation is It will decline.

By the way, in order to solve the problem that the mechanical property at high temperature of the electrolyte made of the perfluoroalkylsulfonic acid polymer is low due to the low thermal deformation temperature, an aromatic polymer used in engineer plastics and the like in recent years. A solid polymer electrolyte membrane using sapphire has been developed.

For example, US Pat. No. 5,403,675 (Patent Document 1) discloses a solid polymer electrolyte made of sulfonated rigid polyphenylene. This polymer is mainly composed of a polymer obtained by polymerizing an aromatic compound comprising a phenylene chain, and this is reacted with a sulfonating agent to introduce a sulfonic acid group. The electrolyte membrane made of this polymer has a heat distortion temperature of 180 ° C. or higher and is excellent in creep resistance at high temperatures.

US Pat. No. 5,403,675

The problem to be solved by the present invention is to provide an aromatic copolymer having a sulfonic acid group having high radical resistance without impairing proton conductivity at low humidity.

The present inventors have intensively studied to solve the above problems. As a result, it has been found that the above problems can be solved by an aromatic copolymer having a specific structural unit, and the present invention has been completed.

Aspects of the present invention are shown in [1] to [7] below.
[1] An aromatic copolymer containing a structural unit represented by the following formula (1) and a structural unit represented by the following formula (4).

(In the above formula (1), each R ¹ is independently a halogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 0 to 3, and k represents an integer of 1 to 4. However, a + k ≦ 4, and a plurality of R ¹ may be the same or different.

(In the formula (4), each E is independently at least one selected from the group consisting of —CO—, —SO ₂ —, —SO—, —CONH—, —NHCO—, and —COO— groups. Ar ³¹ , Ar ³² , and Ar ³³ each independently represents at least one structure selected from the group consisting of a benzene ring, a naphthalene ring, and a nitrogen-containing heterocyclic ring, each of which may be substituted with a fluorine atom. Indicates.

R ³¹ is at least one selected from the group consisting of a direct bond, —O (CH ₂ ) _p —, —O (CF ₂ ) _p —, — (CH ₂ ) _p —, and — (CF ₂ ) _p —. (P represents an integer of 1 to 12). e represents an integer of 0 to 10, f represents an integer of 1 to 5, and g represents an integer of 0 to 4. )

[2] The aromatic copolymer of [1], wherein at least two structural units represented by the formula (1) are continuous.
[3] The number ratio of phosphonic acid groups and sulfonic acid groups contained in the aromatic copolymer is in the range of 0.001 to 0.5 (phosphonic acid group / (phosphonic acid group + sulfonic acid group)). Aromatic copolymer of [1] or [2].
[4] A polymer electrolyte comprising the aromatic copolymer of [1] to [3].
[5] A solid polymer electrolyte membrane comprising the aromatic copolymer of [1] to [4].
[6] A membrane-electrode assembly comprising the polymer electrolyte membrane according to [5] above and a catalyst layer and a gas diffusion layer in contact with both sides of the polymer electrolyte membrane.
[7] A polymer electrolyte fuel cell having the membrane-electrode assembly according to [6].

Since the aromatic copolymer having a sulfonic acid group according to the present invention has a specific structural unit, it has high radical resistance without impairing proton conductivity at low humidity. Further, when combined with a specific aromatic structural unit, a solid polymer electrolyte and a proton conductive membrane having high dimensional stability and high mechanical strength can be obtained.

Also, since the swelling in hot water and the shrinkage during drying are small, the heat resistance and durability are high, the change in the molecular weight of the membrane after power generation is low, and the sulfonic acid retention is high. Therefore, the aromatic block copolymer having a sulfonic acid group according to the present invention can be suitably used for a proton conductive membrane for a fuel cell.

Hereinafter, the aromatic block copolymer, the solid polymer electrolyte, and the proton conductive membrane according to the present invention will be described in detail.

[Aromatic copolymer]
The aromatic copolymer of the present invention has a structural unit having a sulfonic acid group and a structural unit having a phosphonic acid group. As long as it has these segments, the structure of the copolymer is not particularly limited, and may be a random copolymer or a block copolymer, or a mixture thereof. In particular, in the present invention, a block copolymer is preferable.

(Structural unit having a sulfonic acid group)
The structural unit having a sulfonic acid group of the present invention is represented by the following formula (1).

In the above formula (1), each R ¹ is independently a halogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms, Represents an integer of 0 to 3, and k represents an integer of 1 to 4. It is an integer of a + k ≦ 4. The plurality of R ¹ may be the same or different.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms in R ¹ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a tetramethylbutyl group, an amyl group, C1-C20 alkyl groups such as pentyl and hexyl groups; C3-C20 cycloalkyl groups such as cyclopentyl and cyclohexyl groups; C6-C20 aromatics such as phenyl, naphthyl and biphenyl groups Group hydrocarbon group; alkenyl groups having 2 to 20 carbon atoms such as vinyl group and allyl group.

Examples of the monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms in R ¹ include a halogenated alkyl group having 1 to 20 carbon atoms, a halogenated cycloalkyl group having 3 to 20 carbon atoms, and 6 to 20 carbon atoms. And halogenated aromatic hydrocarbon groups. Examples of the halogenated alkyl group include a trichloromethyl group, a trifluoromethyl group, a tribromomethyl group, a pentachloroethyl group, a pentafluoroethyl group, and a pentabromoethyl group; and the halogenated aromatic hydrocarbon group. Examples thereof include a chlorophenyl group and a chloronaphthyl group.
a is preferably 0 or 1, more preferably 0, from the viewpoint of increasing the density of sulfonic acid groups per unit weight of the structural unit.
k is preferably 1 from the viewpoint of reducing the polymerization reactivity of the main chain phenylene moiety due to steric hindrance due to the presence of a plurality of sulfonic acid groups.

[Structural unit having phosphonic acid group]
The structural unit having a phosphonic acid group is represented by the following formula (4).

In formula (4), each E is independently from a direct bond, —O—, —S—, —CO—, —SO ₂ —, —SO—, —CONH—, —NHCO— or —COO—. 1 shows at least one structure selected from the group consisting of Of these, —CO— and —SO ₂ — are preferable.

Ar ³¹ , Ar ³² , Ar ³³ may be the same or different, and may be substituted with a fluorine atom, and at least one structure selected from the group consisting of a benzene ring, a naphthalene ring, and a nitrogen-containing heterocyclic ring Indicates. The nitrogen-containing heterocycle includes pyrrole, 2H-pyrrole, imidazole, pyrazole, isothiazole, isoxazole, pyridine, pyrazine, pyrimidine, pyridazine, indolizine, isoindole, 3H-indole, indole, 1H-indazole, purine. 4H-quinolidine, quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, carbazole, carboline, phenanthridine, acridine, perimidine, phenanthroline, phenazine, phenothiazine, furazane, phenoxazine, pyrrolidine, pyrroline, imidazoline, Imidazolidine, pyrazolidine, pyrazoline, piperidine, piperazine, indoline, isoindoline, quinuclidine, oxazole, ben Examples include oxazole, 1,3,5-triazine, purine, tetrazole, tetrazine, triazole, phenalsazine, benzimidazole, benzotriazole, thiazole, benzothiazole, and benzothiadiazole, including imidazole, pyridine, 1,3,5- Triazine and triazole are preferred.

R ³¹ is at least one selected from the group consisting of a direct bond, —O (CH ₂ ) _p —, —O (CF ₂ ) _p —, — (CH ₂ ) _p —, and — (CF ₂ ) _p —. (P represents an integer of 1 to 12).
e represents an integer of 0 to 10, preferably 0 to 5, more preferably 0 to 2.

f represents an integer of 1 to 5, preferably 1 to 4, more preferably 1 to 3.
g represents an integer of 0 to 4, preferably 0 to 3, more preferably 0 to 2.
h represents an integer of 0 or 1.
The structural unit having a phosphonic acid group is preferably represented by the following formula (4 ′).

(In the formula (4 ′), E, R ³¹ , e, f, g and h are the same as those in the formula (4).)
Specific examples of the structural unit having a phosphonic acid group include the following.

Since the polyarylene copolymer of the present invention contains a structural unit having a phosphonic acid group, durability can be improved while maintaining high proton conductivity, hot water resistance, and mechanical strength. It is assumed that the durability is improved because radical resistance to peroxide is improved by introducing a phosphonic acid group. In particular, when an aromatic copolymer is synthesized using a monomer that is a structural unit having a phosphonic acid group, the phosphonic acid group is not introduced into the structural unit having an aromatic structure described later. Because it does not affect hydrophobicity, it is easy to maintain hot water resistance and mechanical strength. In a polymer electrolyte fuel cell, hydrogen peroxide is generated and decomposed due to side reactions during power generation to generate hydroxy radicals. This peroxide radical is believed to cause oxidative degradation of the electrolyte polymer in the membrane, causing breakage of the membrane and the like.
In order to suppress this deterioration reaction, it is only necessary to impart an antioxidant ability to hydrogen peroxide or the like. For this purpose, it is preferable to introduce a phosphonic acid group into the electrolyte. Moreover, although the specific mechanism is not clarified, a phosphoric acid compound such as a phosphonic acid group has an antioxidant ability and is effective in preventing deterioration of the electrolyte membrane in the fuel cell.
The phosphonic acid group functions to trap and inactivate Fe ²⁺ ions and Cu ²⁺ ions that promote the decomposition of hydrogen peroxide into hydroxy radicals.
The phosphate compound has a chain initiation inhibiting function, a chain inhibiting function, and a peroxide decomposing function, and is used as an antioxidant. * Reference Document JP 2004-134294 A In particular, in the above formula (1), h = 1, and E is a —CO—, —SO ₂ —, —SO—, —CONH—, —COO— group. In other words, this means that a phosphonic acid group is introduced into an aromatic ring having a low electron density, and such a polyarylene-based copolymer has high radical resistance to peroxide and proton conduction. The degree can be kept higher. When h = 0 and R ³¹ is a direct bond, the phosphonic acid group is directly bonded to the benzene ring. In this case as well, the polyarylene-based copolymer has high radical resistance to peroxide and can maintain higher proton conductivity.

Furthermore, in the present invention, since it is introduced in the state of a deprotected phosphonic acid group instead of a phosphonic acid ester group, the proton conductivity is greatly reduced by introduction like a non-conductive phosphonic acid ester group. The conductivity can be maintained without doing so.

In addition, the polyarylene polymer of the present invention includes a structural unit represented by the above formula (1) and a structural unit represented by the above formula (4) from the viewpoint of mechanical strength and hot water resistance of the obtained electrolyte membrane. It is desirable that at least one structural unit selected from the group is preferably at least 2 consecutive units, more preferably at least 3 consecutive units, more preferably at least 5 consecutive units, and at least 10 consecutive units. It is particularly desirable.
Usually, when calculated from the composition ratio, two or more structural units (1) and (4) are continuous. The continuity of such structural units can be proved by NMR or the like.

The number ratio of the phosphonic acid group and the sulfonic acid group contained in the aromatic copolymer may be in the range of 0.001 to 0.5 in terms of (phosphonic acid group / (phosphonic acid group + sulfonic acid group)). Preferably, it is in the range of 0.005 to 0.2, more preferably in the range of 0.01 to 0.1, and still more preferably in the range of more than 0.03 and less than 0.07. When phosphonic acid groups are contained in such a ratio, there is no significant decrease in conductivity, and radical resistance can be increased.
In particular, when (phosphonic acid group / (phosphonic acid group + sulfonic acid group)) is less than 0.07, weight retention in the Fenton test is improved while maintaining proton conduction. Further, when (phosphonic acid group / (phosphonic acid group + sulfonic acid group)) exceeds 0.03 and less than 0.07, weight retention and ion exchange capacity retention in the Fenton test are maintained while maintaining proton conduction. Both rates can be achieved.

In addition, the aromatic copolymer of the present invention has a structural unit represented by the above formula (1) and a structural unit represented by the above formula (4) from the viewpoint of mechanical strength and hot water resistance of the obtained film. Are preferably directly bonded to each other.
In the present invention, in addition to the above, a structural unit having an aromatic structure and a structural unit having a divalent heterocyclic group containing nitrogen may be included as necessary.

(Structural unit having aromatic structure)
The aromatic copolymer of the present invention is represented by the following formula (3) as a structural unit having an aromatic structure in addition to the structural unit represented by the above formula (1) and the structural unit represented by the above formula (4). Structural units can be included.
The structural unit having an aromatic structure is represented by the following formula (3).

In the above formula (3), Ar ²¹ , Ar ²² , Ar ²³ and Ar ²⁴ each independently represent a divalent group having a benzene ring, condensed aromatic ring (such as a naphthalene ring) or a nitrogen-containing heterocyclic ring structure. .

However, in Ar ²¹ , Ar ²² , Ar ²³ , Ar ²⁴ , some or all of the hydrogen atoms may be fluorine-substituted, nitro group, nitrile groups, or some or all of the hydrogen atoms may be halogen-substituted. It may be substituted with at least one atom or group selected from the group consisting of an alkyl group, an allyl group or an aryl group.

A and D are each independently a direct bond or —CO—, —COO—, —CONH—, —SO ₂ —, —SO—, — (CF ₂ ) ₁ — (l is an integer of 1 to 10 A), — (CH ₂ ) _l — (l is an integer of 1 to 10), —CR ′ ₂ — (R ′ represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group and a halogenated hydrocarbon group) ), A cyclohexylidene group, a fluorenylidene group, —O— or S—, B is an oxygen atom or a sulfur atom, s and t each independently represent an integer of 0 to 4, and r is 0 Or an integer greater than or equal to 1 is shown.

The structural unit having an aromatic structure is preferably one represented by the following formula (3-1).

[In the formula (3-1), A and D are independently a direct bond, or —CO—, —SO ₂ —, —SO—, —COO—, —CONH—, — (CF ₂ ) _l — (l is 1 is an integer of 1 to 10), — (CH ₂ ) ₁ — (l is an integer of 1 to 10), —CR ′ ₂ — (R ′ is an aliphatic hydrocarbon group, aromatic hydrocarbon group and halogen Represents at least one structure selected from the group consisting of a cyclohexylidene group, a fluorenylidene group, —O—, and —S—, and B is independently an oxygen atom or a sulfur atom, R ¹ to R ¹⁶ may be the same or different from each other, and may be a hydrogen atom, a fluorine atom, a nitro group, a nitrile group, an alkyl group, an allyl group or At least one atom selected from the group consisting of aryl groups; A group. s and t represent integers of 0 to 4 (0, 1, 2), and r represents 0 or an integer of 1 or more. ]
Specific examples of such a structural unit include the following.

When the aromatic ring structural unit as described above is contained, the hydrophobicity of the copolymer is remarkably improved. For this reason, the outstanding hot water tolerance can be provided, providing the proton conductivity similar to the past. Moreover, what contains a nitrile group in the said structural unit can manufacture the copolymer with a small shrinkage | contraction at the time of swelling in hot water and drying.

(Structural unit having a divalent heterocyclic group containing nitrogen)
Furthermore, in the present invention, in addition to the structural unit represented by the above formula (1) and the structural unit represented by the above formula (4), a structure having a divalent heterocyclic group containing nitrogen represented by the following formula (2) Units may be included.

In the above formula (2), Ar ¹ represents a divalent organic group having a heterocyclic structure containing nitrogen, preferably an organic group having 3 to 30 carbon atoms having a heterocyclic structure containing nitrogen, And a divalent heterocyclic group containing nitrogen and a group represented by the following formula (2-1).

In the above formula (2-1), R ^h represents a monovalent heterocyclic group containing nitrogen, Ar ² represents a trivalent aromatic group, and R ^s represents a divalent fatty acid having 1 to 20 carbon atoms. An aromatic hydrocarbon group, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent aromatic group, wherein Q ¹ and Q ² are each independently a direct bond, —O—, — It represents at least one structure selected from the group consisting of S—, —CO—, —SO ₂ — or —SO—, and n1 represents an integer of 0-2.

^Examples of the monovalent heterocyclic group containing nitrogen represented by R ^h include nitrogen-containing 5-membered and 6-membered ring structures. Further, the number of nitrogen atoms in the heterocycle is not particularly limited as long as it is 1 or more, and the heterocycle may contain oxygen or sulfur in addition to nitrogen. Specific examples of the monovalent heterocyclic group containing nitrogen constituting R ^h include pyrrole, thiazole, isothiazole, oxazole, isoxazole, pyridine, imidazole, imidazoline, pyrazole, 1,3,5-triazine, and pyrimidine. , Pyritazine, pyrazine, indole, quinoline, isoquinoline, purine, benzimidazole, benzoxazole, benzthiazole, tetrazole, tetrazine, triazole, carbazole, acridine, quinoxaline, quinazoline and their derivatives carbon or nitrogen Is a group having a structure in which a hydrogen atom bonded to is pulled out. These nitrogen-containing heterocyclic groups may have a substituent. Examples of the substituent include alkyl groups such as a methyl group, an ethyl group, and a propyl group, and aryl groups such as a phenyl group, a toluyl group, and a naphthyl group. Group, cyano group, fluorine atom and the like.

Examples of the trivalent aromatic group represented by Ar ² include a trivalent monocyclic aromatic group derived from a phenyl group, a trivalent condensed ring aromatic group derived from a naphthyl group, pyridine, quinoxaline, and thiophene. And trivalent aromatic heterocyclic groups derived from the above. Of these, a monocyclic aromatic group is preferable.
Examples of the divalent aromatic group represented by R ^s include divalent monocyclic aromatic groups such as 1,3-phenylene group and 1,4-phenylene group, 1,3-naphthalenediyl group, 1,4 -Divalent condensation of naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalenediyl group, etc. Examples thereof include a divalent aromatic heterocyclic group such as a ring aromatic group, a pyridinediyl group, a quinoxalinediyl group, and a thiophenediyl group. Examples of the divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms and the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^s include a methylene group, an ethylene group, and a cyclohexylene group. Is mentioned. In the present invention, R ^s is preferably a divalent monocyclic aromatic group.
The divalent to trivalent binding sites are not particularly limited.

Specific examples of the divalent heterocyclic group containing nitrogen represented by Ar ¹ include a pyrrole diyl group, a 2H-pyrrole diyl group, an imidazole diyl group, a pyrazole diyl group, an isothiazole diyl group, an isoxazole diyl group, and a pyridinediyl group. Group, pyrazinediyl group, pyrimidinediyl group, pyridazinediyl group, indolizinediyl group, isoindolediyl group, 3H-indolediyl group, indolediyl group, 1H-indazolediyl group, purinediyl group, 4H-quinolidinediyl group, quinolinediyl group, Isoquinolinediyl group, phthalazinediyl group, naphthyridinediyl group, quinoxalinediyl group, quinazolinediyl group, cinnolinediyl group, pteridinediyl group, carbazolediyl group, carbolinediyl group, phenanthridinediyl group, Clidinediyl group, perimidinediyl group, phenanthrolinediyl group, phenazinediyl group, phenothiazinediyl group, furazanediyl group, phenoxazinediyl group, pyrrolidinediyl group, pyrrolindiyl group, imidazolinediyl group, imidazolidinediyl group, pyrazolidinediyl group, pyrazolinediyl Group, piperidinediyl group, piperazinediyl group, indolinediyl group, isoindolinediyl group, quinuclidinediyl group, oxazolediyl group, benzoxazolediyl group, 1,3,5-triazinediyl group, purinediyl group, tetrazolediyl group , Tetrazinediyl group, triazolediyl group, phenalsazinediyl group, benzimidazolediyl group, benzotriazolediyl group, thiazolediyl group, benzothiazolediyl And a structure derived from at least one selected from the group consisting of a group and a benzothiadiazolediyl group, or at least one structure selected from the group consisting of a structure represented by the following formula.

[In the above formula, among the single wires at the ends of the structural units, those on which one or more substituents are not displayed mean connection with adjacent structural units. ]

Examples of the divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms represented by R ^s include a methylene group, a propylene group, and a butylene group.
Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^s include a cyclopentylene group, a cyclohexylene group, and a cycloheptylene group. In the present invention, R ^s is preferably a divalent monocyclic aromatic group.

By including a structural unit having a nitrogen-containing heterocyclic group as described above, a solid polymer electrolyte membrane having high sulfonic acid stability at high temperatures without imparting basicity and impairing proton conductivity is obtained. Obtainable.

In the copolymer according to the present invention, the amount of each structural unit is determined according to desired properties such as ion exchange capacity and molecular weight.
The polymer of the present invention contains the structural units represented by the formulas (1) and (2) in the ratio of 0.5 to 99.9 mol%, preferably 10 to 99.5 mol% in the formula (3). It is desirable that the structural unit represented is 0.1 to 99.5 mol%, preferably 0.5 to 89.5 mol%.

Further, when the structural unit represented by the formula (2) is included, it may be 0.01 mol% or more, preferably 20 mol% or less of all the structural units.
The molecular weight of the aromatic copolymer of the present invention is 10,000 to 1,000,000, preferably 20,000 to 800,000, more preferably 50,000 to 30 in terms of polystyrene-equivalent weight average molecular weight by gel permeation chromatography (GPC). Ten thousand.

The ion exchange capacity of the aromatic copolymer according to the present invention is usually 0.3 to 6 meq / g, preferably 0.5 to 4 meq / g, more preferably 0.8 to 3.5 meq / g. When the ion exchange capacity is within this range, proton conductivity is high, power generation performance can be enhanced, and sufficiently high water resistance can be provided.

The above-mentioned ion exchange capacity can be adjusted by changing the type, usage ratio, and combination of each structural unit. Therefore, it can be adjusted by changing the charge amount ratio and type of the precursor (monomer / oligomer) that induces the structural unit during polymerization.

In general, as the number of structural units containing sulfonic acid groups and phosphonic acid groups increases, the ion exchange capacity increases and proton conductivity increases, but the water resistance tends to decrease. On the other hand, when these structural units decrease, ion exchange increases. The capacity decreases and the water resistance increases, but the proton conductivity tends to decrease.

[Method for producing aromatic copolymer]
The aromatic copolymer of the present invention is obtained, for example, by the method described in JP-A No. 2004-137444, the compound (A) from which the structural unit represented by the above formula (1) is derived, and the above formula (4). The compound derived from the structural unit represented by (B) and, if necessary, the compound derived from the other structural unit are copolymerized to convert the sulfonic acid ester group into a sulfonic acid group, or phosphonic acid ester It can be synthesized by converting a group or a phosphonic acid group into a phosphonic acid group.

Compound (A) from which the structural unit represented by the above formula (1) is derived (hereinafter also referred to as “Compound A”)
The structural unit represented by the above formula (1) can be introduced by using, for example, a compound represented by the following formula (1-1) as a polymerization raw material for the aromatic copolymer.

In the above formula (1-1), Z ¹ is a halogen atom, a nitro group, an atom or group selected from —SO ₂ CH ₃ and —SO ₂ CF ₃ , and R ^a is a group represented by —OR ^b (R ^b Represents a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms.), A hydrocarbon group having 1 to 20 carbon atoms, and a 1 to 20 carbon atom substituted with at least one group selected from hydrocarbon groups which showed amino group, R ^1, a, k is R ^1, a, synonymous with k in the formula (1).

R ^b may be the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms, preferably a hydrocarbon group having 4 to 20 carbon atoms. Specifically, tert-butyl group, iso-butyl group, n-butyl group, sec-butyl group, neopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, cyclopentylmethyl group, cyclohexylmethyl group, adamantylmethyl group, adamantylmethyl group 2-ethylhexyl group, bicyclo [2.2.1] heptyl group, bicyclo [2.2.1] heptylmethyl group, tetrahydrofurfuryl group, 2-methylbutyl group, 3,3-dimethyl-2,4-dioxolane Examples include a straight chain hydrocarbon group such as a methyl group, a branched hydrocarbon group, an alicyclic hydrocarbon group, and a hydrocarbon group having a 5-membered heterocycle. Of these, n-butyl group, neopentyl group, tetrahydrofurfuryl group, cyclopentylmethyl group, cyclopentyl group, cyclohexyl group, cyclohexylmethyl group, adamantyl, from the viewpoints of availability, solubility of other compounds, and polymerization reactivity A methyl group and a bicyclo [2,2,1] heptylmethyl group are preferred, and a neopentyl group is most preferred.

A phosphonic acid compound derived from a structural unit having a phosphonic acid group (hereinafter sometimes referred to as compound (B))
The structural unit having a phosphonic acid group is introduced by using, for example, an aromatic compound represented by the following general formula (4-1) or (4-2) as a polymerization raw material for an aromatic copolymer. be able to.

In the formulas (4-1) and (4-2), E, Ar ³¹ , Ar ³² , Ar ³³ , e, f, h, and g are the same as in the above formula (4).

R ³¹ is at least one selected from the group consisting of a direct bond, —O (CH ₂ ) _p —, —O (CF ₂ ) _p —, — (CH ₂ ) _p —, and — (CF ₂ ) _p —. (P represents an integer of 1 to 12).

R ³² represents an alkyl group, a fluorine-substituted alkyl group, an aryl group, a metal ion, an onium ion, or hydrogen. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an amyl group, a hexyl group, a cyclohexyl group, and an octyl group. Examples of the fluorine-substituted alkyl group include a trifluoromethyl group, a pentafluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group. Examples of the allyl group include a propenyl group, and examples of the aryl group include a phenyl group and a pentafluorophenyl group. Among these, a methyl group, an ethyl group, a propyl group, an isopropyl group, and a phenyl group are preferable.

Examples of the metal ion include alkali metal sodium ion, potassium ion, lithium ion, alkaline earth metal magnesium and calcium. Of these, sodium ion, potassium ion, and lithium ion are particularly preferable.

Examples of onium ions include ammonium, phosphonium, oxonium, sulfonium and the like.
X represents an atom or group selected from halogen atoms excluding fluorine (chlorine, bromine, iodine) and —OSO ₂ Rb (where Rb represents an alkyl group, a fluorine-substituted alkyl group or an aryl group). Of these, chlorine and bromine are preferred.

Examples of the compound represented by the formula (4-1) include the structures shown below.

Furthermore, compounds in which a chlorine atom is replaced with a bromine atom, and isomers having different bonding positions of chlorine and bromine atoms can be exemplified. Further, compounds in which —CO— bond is replaced with —SO ₂ — bond, —SO— bond, —COO— bond, —OCO— bond, —CONH— bond, —NHCO— bond can be exemplified. Further, the bonding position of the phosphonic acid group is not particularly limited, and may be o-position, m-position or p-position.

In the formula (4-2), R ³³ is represented _by- (CR ³⁴ R ³⁵ ) _h1- (CR ³⁶ R ³⁷ ) _h2- (CR ³⁸ R ³⁹ ) _h3- (CR ⁴⁰ R ⁴¹ ) _h4- Indicates a valent group. Preferably, R ³³ is an alkylene group which may be branched.

R ³⁴ to R ⁴¹ may be the same as or different from each other, and each represents a group selected from a hydrogen atom, a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, an allyl group, and an aryl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an amyl group, a hexyl group, a cyclohexyl group, and an octyl group. Examples of the fluorine-substituted alkyl group include a trifluoromethyl group, a pentafluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group. Examples of the allyl group include a propenyl group, and examples of the aryl group include a phenyl group and a pentafluorophenyl group. Among these, a methyl group, an ethyl group, a propyl group, an isopropyl group, and a phenyl group are preferable.

h1, h2, h3, and h4 may be the same as or different from each other, and are 0 or 1, and h1 + h2 + h3 + h4 is 2 or more.
Specific examples of the compound represented by the formula (4-2) include the structures shown below.

Furthermore, compounds in which a chlorine atom is replaced with a bromine atom, and isomers having different bonding positions of chlorine and bromine atoms can be exemplified. Further, compounds in which —CO— bond is replaced with —SO ₂ — bond, —SO— bond, —COO— bond, —OCO— bond, —CONH— bond, —NHCO— bond can be exemplified. The bonding position of the phosphonic acid group is not particularly limited, and may be o-position, m-position or p-position.

In addition, as a derivative of the aromatic compound according to the present invention represented by the above general formulas (4-1) and (4-2), a compound in which a chlorine atom is replaced with a bromine atom in the above compound, There -SO ₂ - compound replaced by a chlorine atom in the compound is replaced with a bromine atom, and -CO- is -SO ₂ - can also be mentioned such compounds replaced.

The above compound can be prepared by a substitution reaction with a precursor in which a bromine atom is introduced in advance at a substitution site where a phosphonic acid group is introduced, and a phosphonic acid ester, phosphonate, or phosphonic acid. In the case of a phosphonate, neutralization may be performed after introducing phosphonic acid.

Compound (C) derived from the structural unit represented by the above formula (3) (hereinafter also referred to as “compound C”)
A structural unit having an aromatic structure, derived from a monomer having the following formula (3-2).

(In the formula (3-2), Ar ²¹ , Ar ²² , Ar ²³ , and Ar ²⁴ are at least one structure selected from the group consisting of a benzene ring, a condensed aromatic ring (such as a naphthalene ring), and a nitrogen-containing heterocyclic ring. However, Ar ²¹ , Ar ²² , Ar ²³ , and Ar ²⁴ are each a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group in which part or all of them are fluorine-substituted, an allyl group, an aryl group, It may be substituted with a nitro group or a nitrile group.

X represents at least one structure selected from the group consisting of chlorine, bromine, iodine, methanesulfonyl group, trifluoromethanesulfonyl group, benzenesulfonyl group, and toluenesulfonyl group.

A and D are independently a direct bond, or —CO—, —COO—, —CONH—, —SO ₂ —, —SO—, — (CF ₂ ) ₁ — (l is an integer of 1 to 10), — (CH ₂ ) ₁ — (wherein 1 is an integer of 1 to 10), —CR ′ ₂ — (R ′ represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group and a halogenated hydrocarbon group), cyclohexene Represents at least one structure selected from the group consisting of a silidene group, a fluorenylidene group, —O—, and —S—, B is independently an oxygen atom or a sulfur atom, and s and t are 0-4 An integer is shown, and r is 0 or an integer of 1 or more. )
The structural unit having an aromatic structure can be obtained by using, for example, an oligomer represented by the following general formula (3-3) as a polymerization raw material for a polyarylene-based copolymer.

[In the above formula (3-3), X represents at least one structure selected from the group consisting of chlorine, bromine, iodine, methanesulfonyl group, trifluoromethanesulfonyl group, and benzenesulfonyl group. A and D are independently a direct bond, or —CO—, —SO ₂ —, —SO—, — (CF ₂ ) _l — (l is an integer of 1 to 10), — (CH ₂ ) _l — ( l is an integer of 1 to 10), —CR ′ ₂ — (R ′ represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group and a halogenated hydrocarbon group), a cyclohexylidene group, a fluorenylidene group, — At least one structure selected from the group consisting of O— and —S—, wherein B is independently an oxygen atom or a sulfur atom;
R ¹ to R ¹⁶ may be the same as or different from each other, and are a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group in which a part or all of them are halogenated, an allyl group, an aryl group, a nitro group, a nitrile group. At least one atom or group selected from the group consisting of
s and t are integers of 0 to 4, and r is 0 or an integer of 1 or more. ]
Specific examples of the oligomer represented by the above formula (3-3) include the following.

Moreover, the compound etc. which the chlorine atom replaced the bromine atom in the said compound are mentioned. In addition, isomers having different bonding positions of chlorine atoms and bromine atoms can also be mentioned.

The oligomers represented by the above formulas (3-2) and (3-3) can be produced, for example, by copolymerizing the following monomers. When r = 0 in the formulas (3-2) and (3-3), for example, 4,4′-dichlorobenzophenone, 4,4′-dichlorobenzanilide, 2,2-bis (4-chlorophenyl) difluoromethane, 2,2-bis (4-chlorophenyl) -1,1,1,3,3,3-hexafluoropropane, 4-chlorobenzoic acid-4-chlorophenyl ester, bis (4-chlorophenyl) sulfoxide, bis (4- Chlorophenyl) sulfone and 2,6-dichlorobenzonitrile.

These compounds include compounds in which chlorine atoms are replaced by bromine atoms or iodine atoms. In the case of r = 1, for example, compounds described in JP-A No. 2003-113136 can be exemplified.

In the case of r ≧ 2, for example, Japanese Patent Application Laid-Open No. 2004-137444, Japanese Patent Application Laid-Open No. 2004-244517, Japanese Patent Application No. 2003-143914 (Japanese Patent Application Laid-Open No. 2004-346164), Japanese Patent Application No. 2003-348523 (Japanese Patent Application Laid-Open No. No. 112985), Japanese Patent Application No. 2003-348524, Japanese Patent Application No. 2004-211739 (Japanese Patent Laid-Open No. 2006-28414), Japanese Patent Application No. 2004-21740 (Japanese Patent Laid-Open No. 2006-28415), and the like. Can do.

Compound (D) derived from a structural unit having a nitrogen-containing heterocyclic group (hereinafter also referred to as “compound D”)
The structural unit having a nitrogen-containing heterocyclic group represented by the above formula (2) is obtained by using, for example, an aromatic group by using a compound represented by the following formula (2-2) as a raw material for an aromatic copolymer. It can be introduced into the polymer.

In the formula (2-2), Ar ¹ has the same meaning as Ar ¹ in the formula (2), and Z ³ is an atom selected from a halogen atom, a nitro group, a —SO ₃ CH ₃ group, and SO ₃ CF _3. Or a group.

When Ar ¹ is a divalent heterocyclic group containing nitrogen, specific examples of the compound represented by the above formula (2-2) include 1-methyl-2,5-dichloropyrrole, 1- Hexyl-2,5-dibromopyrrole, 1-octyl-2,5-dichloropyrrole, 2,5-dichloropyridine, 3,5-dichloropyridine, 2,5-dibromopyridine, 3-methyl-2,5-dichloro Pyridine, 3-hexyl-2,5-dichloropyridine, 5,5′-dichloro-2,2′-bipyridine, 3,3′-dimethyl-5,5′-dichloro-2,2′-bipyridine, 3, 3'-dioctyl-5,5'-dibromo-2,2'-bipyridine, 2,5-dichloropyrimidine, 2,5-dibromopyrimidine, 5,8-dichloroquinoline, 5,8-dibromoquinoline, 2,6 -Dichloroquinoline, 1,4-dichloroisoquinoline, 5,8-dibromoisoquinoline, 4,7-dibromo-2,1,3-benzothiadiazole, 4,7-dichlorobenzimidazole, 5,8-dichloroquinoxaline, 5,8-dichloro- Examples include 2,3-diphenylquinoxaline and 2,6-dibromoquinoxaline.

In the case where Ar ² is a group represented by the above formula (2-1), the compound represented by the above formula (2-2) is specifically a compound represented by the following formula (2-3) Can be mentioned.

In the above formula (2-3), R ^h , R ^s , Ar ² , Q ¹ , Q ² , n 1 are R ^h , R ^s , Ar ² , Q ¹ , Q ² , It is synonymous with n, and Z ³ represents an atom or group selected from a halogen atom, a nitro group, a —SO ₃ CH ₃ group, and SO ₃ CF ₃ .

Specific examples of the compound represented by the above formula (2-3) include the following compounds.

Furthermore, compounds in which a chlorine atom is replaced with a bromine atom, and isomers having different bonding positions of chlorine and bromine atoms can be exemplified. Further, a compound in which the —CO— bond is replaced with a —SO ₂ — bond can be exemplified. These compounds may be used alone or in combination of two or more.

In order to obtain an aromatic copolymer for the purpose of the polymerization method , first, the above-mentioned various compounds are copolymerized to obtain a precursor. This copolymerization is carried out in the presence of a catalyst, and the catalyst used in this case is a catalyst system containing a transition metal compound. This catalyst system is (1) a transition metal salt and a ligand. A compound (hereinafter referred to as “ligand component”) or a transition metal complex coordinated with a ligand (including a copper salt) and (2) a reducing agent as essential components, and further increase the polymerization rate. Therefore, salts other than transition metal salts may be added.

Here, transition metal salts include nickel compounds such as nickel chloride, nickel bromide, nickel iodide, nickel acetylacetonate, palladium compounds such as palladium chloride, palladium bromide, palladium iodide, iron chloride, iron bromide And iron compounds such as iron iodide and cobalt compounds such as cobalt chloride, cobalt bromide and cobalt iodide. Of these, nickel chloride, nickel bromide and the like are particularly preferable. Examples of the ligand include triphenylphosphine, tri (2-methyl) phenylphosphine, tri (3-methyl) phenylphosphine, tri (4-methyl) phenylphosphine, 2,2′-bipyridine, 1,5- Examples thereof include cyclooctadiene and 1,3-bis (diphenylphosphino) propane. Triphenylphosphine, tri (2-methyl) phenylphosphine, and 2,2′-bipyridine are preferable. The said ligand can be used individually by 1 type or in combination of 2 or more types.

Furthermore, as the transition metal (salt) in which the ligand is coordinated in advance, for example, nickel chloride bis (triphenylphosphine), nickel chloride bis (tri (2-methyl) phenylphosphine), nickel bromide bis (triphenyl) Phosphine), nickel iodide bis (triphenylphosphine), nickel nitrate bis (triphenylphosphine), nickel chloride (2,2′bipyridine), nickel bromide (2,2′bipyridine), nickel iodide (2,2) 'Bipyridine), nickel nitrate (2,2'bipyridine), bis (1,5-cyclooctadiene) nickel, tetrakis (triphenylphosphine) nickel, tetrakis (triphenylphosphite) nickel, tetrakis (triphenylphosphine) palladium Nickel chloride bis (Triphenylphosphine), nickel chloride bis (tri (2-methyl) phenylphosphine), and nickel chloride (2,2′bipyridine) are preferred.

Examples of the reducing agent that can be used in the catalyst system of the present invention include iron, zinc, manganese, aluminum, magnesium, sodium, and calcium, and zinc, magnesium, and manganese are preferable. These reducing agents can be used after being more activated by bringing them into contact with an acid such as an organic acid.

Examples of salts other than transition metal salts that can be used in the catalyst system of the present invention include sodium compounds such as sodium fluoride, sodium chloride, sodium bromide, lithium bromide, sodium iodide, sodium sulfate, and fluorides. Examples include potassium compounds such as potassium, potassium chloride, potassium bromide, potassium iodide, and potassium sulfate, and ammonium compounds such as tetraethylammonium fluoride, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, and tetraethylammonium sulfate. However, lithium bromide, sodium bromide, sodium iodide, potassium bromide, tetraethylammonium bromide and tetraethylammonium iodide are preferred.

The proportion of each component in the catalyst system is such that the transition metal salt or the transition metal (salt) coordinated with the ligand can be a structural unit represented by the above general formula (1) and the above general formula. The amount is generally 0.0001 to 10 mol, preferably 0.01 to 0.5 mol, based on 1 mol in total with the compound B that can be the structural unit represented by (4). Within this range, the polymerization reaction proceeds sufficiently, and the catalytic activity is high and the molecular weight can be increased. When the amount is less than the above range, the polymerization reaction does not proceed sufficiently. On the other hand, when the amount is too large, the molecular weight is lowered. When a transition metal salt and a ligand are used in the catalyst system, the amount of the ligand used is usually 0.1 to 100 mol, preferably 1 to 10 mol, per 1 mol of the transition metal salt. Within this range, a catalyst having a high catalytic activity and a high molecular weight can be obtained.

The ratio of the reducing agent used in the catalyst system is 1 in total of the compound A that can be the structural unit represented by the general formula (1) and the compound B that can be the structural unit represented by the general formula (4). The amount is usually 0.1 to 100 mol, preferably 1 to 10 mol, relative to mol. If it exists in this range, superposition | polymerization will fully advance and a polymer can be obtained with a high yield. Further, when the lower limit of the above range is satisfied, the polymerization does not proceed sufficiently. On the other hand, when the upper limit is exceeded, there is a problem that it is difficult to purify the resulting polymer.

Further, when a salt other than a transition metal salt is used in the catalyst system, the use ratio thereof is a compound A that can be a structural unit represented by the general formula (1) and a structure represented by the general formula (4). The amount is generally 0.001 to 100 mol, preferably 0.01 to 1 mol, relative to a total of 1 mol with compound B which can be a unit. Within this range, the effect of increasing the polymerization rate is high, and purification of the polymer that removes these is easy.

In addition, when it contains other compounds C and D, it becomes the catalyst amount with respect to these total amounts.
Examples of the polymerization solvent that can be used in the present invention include tetrahydrofuran, cyclohexanone, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, 1-methyl-2-pyrrolidone, γ-butyrolactone, γ- Examples include butyrolactam, and tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, and 1-methyl-2-pyrrolidone are preferable. These polymerization solvents are preferably used after sufficiently dried. The concentration of the compound A that can be the structural unit represented by the general formula (1) and the compound B that can be the structural unit represented by the general formula (4) in the polymerization solvent is usually 1 to 90% by weight, Preferably, it is 5 to 40% by weight.

When introducing a structural unit having a nitrogen-containing heterocyclic group or other structural unit, the compound C or a monomer corresponding to the other structural unit is added when reacting the compound A and B, or Any one of compounds A and B may be reacted in advance with compound C and the like, and then reacted with the one of compounds A or B that has not yet been reacted. The reaction conditions may be based on the above conditions.

The reaction of compounds A, B, C, etc. corresponds to the composition of each structural unit with the charged amount as it is.
The polymerization temperature for polymerizing the polymer of the present invention is usually 0 to 200 ° C., preferably 50 to 80 ° C. The polymerization time is usually 0.5 to 100 hours, preferably 1 to 40 hours.

In the above production method, the sulfonic acid ester group or phosphonic acid ester group contained in the obtained copolymer is deprotected and converted to a sulfonic acid group or phosphonic acid group.
In particular,
(1) A method in which the aromatic copolymer is added to an excess amount of water or alcohol containing a small amount of hydrochloric acid and stirred for 5 minutes or more. (2) The aromatic copolymer is 80 in trifluoroacetic acid. Method of reacting at a temperature of about 120 ° C. for about 5 to 10 hours (3) 1 to 9 times moles of lithium bromide per mole of sulfonate group (—SO ₃ R) in the aromatic copolymer And a method of reacting the aromatic copolymer in a solution such as N-methylpyrrolidone at a temperature of about 80 to 150 ° C. for about 3 to 10 hours and then adding hydrochloric acid. .

In addition, when it is a sulfonic acid metal salt or a phosphonic acid metal salt, it may be replaced with hydrogen by a method such as ion exchange.

[Polymer electrolyte membrane]
The aromatic copolymer of the present invention includes a proton conducting membrane, an electrolyte for a primary battery, an electrolyte for a secondary battery, a solid polymer electrolyte for a fuel cell, a display element, various sensors, a signal transmission medium, a solid capacitor, and an ion exchange membrane. For example, the membrane state, the solution state, and the powder state may be used. Of these, the membrane state and the solution state are preferable (hereinafter, the membrane state is referred to as a polymer electrolyte membrane).

The solid polymer electrolyte membrane according to the present invention contains the above aromatic copolymer. The dry film thickness of the solid polymer electrolyte membrane according to the present invention is usually 10 to 100 μm, preferably 20 to 80 μm.

The solid polymer electrolyte membrane according to the present invention can also contain a metal compound or a metal ion. Other metal compounds or metal ions include aluminum (Al), manganese (Mn), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W) iron, iron (Fe), Ruthenium (Ru), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), silver (Ag), cerium (Ce), vanadium (V), neodymium (Nd), praseodymium (Pr), Metal compounds containing metal atoms such as samarium (Sm), cobalt (Co), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), and erbium (Er), or these metal ions Can be mentioned.

The solid polymer electrolyte membrane according to the present invention can also contain a fluorine-containing polymer. As the fluorine-containing polymer, a solvent-soluble compound is preferably used because the fluorine-containing polymer can be uniformly dispersed in the pores of the electrolyte membrane or the porous substrate. The fluorine-containing polymer is not particularly limited, and examples thereof include vinylidene fluoride homo (co) polymers, fluoroolefin / hydrocarbon olefin copolymers, fluoroacrylate copolymers, fluoroepoxy compounds and the like. Can be used.
Such a polymer electrolyte membrane according to the present invention preferably has a weight retention by a Fenton test described later of preferably 50% or more, and more preferably 95% or more. The ion exchange capacity retention is preferably 50% or more, and more preferably 95% or more. Those having such weight retention and ion exchange capacity retention have high radical resistance as electrolyte membrane materials, and can sufficiently exhibit effects such as mechanical strength and dimensional stability.

Production method of polymer electrolyte membrane The polymer electrolyte membrane of the present invention is produced by, for example, a casting method in which the aromatic copolymer is mixed in an organic solvent and cast onto a substrate to form a film. can do. Here, the substrate is not particularly limited as long as it is a substrate used in a normal solution casting method. For example, a substrate made of plastic, metal, or the like is used, and preferably a heat treatment such as a polyethylene terephthalate (PET) film. A substrate made of a plastic resin is used.

The solvent for mixing the aromatic copolymer may be a solvent that dissolves the copolymer or a solvent that swells, such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, γ-butyrolactone. , N, N-dimethylacetamide, dimethylsulfoxide, dimethylurea, dimethylimidazolidinone, acetonitrile, and other aprotic polar solvents, dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene, dichlorobenzene and other chlorinated solvents, methanol Alcohols such as ethanol, propanol, iso-propyl alcohol, sec-butyl alcohol, tert-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl Alkylene glycol monoalkyl ethers such as ether, acetone, methyl ethyl ketone, cyclohexanone, ketones such as γ- butyrolactone, tetrahydrofuran, solvents such as ethers 1,3-dioxane and the like. These solvents can be used alone or in combination of two or more. In particular, from the viewpoint of solubility and solution viscosity, N-methyl-2-pyrrolidone (hereinafter also referred to as “NMP”) is preferable.

When a mixture of an aprotic polar solvent and another solvent is used as the solvent, the composition of the mixture is 95-25% by weight of the aprotic polar solvent, preferably 90-25% by weight, The solvent is 5 to 75% by weight, preferably 10 to 75% by weight (however, the total is 100% by weight). When the amount of the other solvent is within the above range, the effect of lowering the solution viscosity is excellent. In this case, the combination of the aprotic polar solvent and the other solvent is preferably NMP as the aprotic polar solvent and methanol having an effect of lowering the solution viscosity in a wide composition range as the other solvent.

The polymer concentration of the solution in which the copolymer and the additive are dissolved depends on the molecular weight of the sulfonic acid-containing aromatic copolymer, but is usually 5 to 40% by weight, preferably 7 to 25% by weight. is there. If the polymer concentration is within the above range, a film having a desired film thickness can be formed, no pinholes are generated, and film formation is easy in terms of solution viscosity. Is excellent.

The solution viscosity is usually 2,000 to 100,000 mPa · s, preferably 3,000 to 50, although depending on the molecular weight of the aromatic copolymer, the polymer concentration, and the concentration of the additive. 000 mPa · s. If the viscosity is within this range, the solution stays well during film formation, does not flow from the substrate, and is low in viscosity, so it can be easily extruded from a die and can be easily formed into a film by the casting method. It becomes.

After film formation as described above, when the obtained undried film is immersed in water, the organic solvent in the undried film can be replaced with water, and the amount of residual solvent in the resulting polymer electrolyte membrane is reduced. can do.

Note that after the film formation, the undried film may be preliminarily dried before the undried film is immersed in water. The preliminary drying is performed by holding the undried film at a temperature of usually 50 to 150 ° C. for 0.1 to 10 hours.

When the undried film is immersed in water and dried as described above, a film with a reduced amount of residual solvent is obtained. The residual solvent amount of the film thus obtained is usually 5% by weight or less. Further, depending on the dipping conditions, the amount of residual solvent in the obtained film can be set to 1% by weight or less. As such conditions, for example, the amount of water used is 50 parts by weight or more with respect to 1 part by weight of the undried film, the temperature of the water during immersion is 10 to 60 ° C., and the immersion time is 10 minutes to 10 hours. is there.

After immersing the undried film in water as described above, the film is dried at 30-100 ° C., preferably 50-80 ° C., for 10-180 minutes, preferably 15-60 minutes, and then at 50-150 ° C. The film can be obtained by vacuum drying under reduced pressure of 500 mmHg to 0.1 mmHg for 0.5 to 24 hours.

The polymer electrolyte membrane obtained by the method of the present invention has a dry film thickness of usually 10 to 100 μm, preferably 20 to 80 μm. In addition, after the aromatic copolymer having the sulfonic acid ester group or the alkali metal salt of sulfonic acid is formed into a film by the method described above, it is subjected to appropriate post-treatment such as hydrolysis and acid treatment. The polymer electrolyte membrane according to the present invention can also be produced. Specifically, an aromatic copolymer having a sulfonic acid ester group or an alkali metal salt of sulfonic acid is formed into a film by the above-described method, and then the membrane is hydrolyzed or acid-treated for hydrolysis. A polymer electrolyte membrane made of a group copolymer can be produced.

Further, when producing the polymer electrolyte membrane, in addition to the above aromatic copolymers, inorganic acids such as sulfuric acid and phosphoric acid, phosphate glass, tungstic acid, phosphate hydrate, β-alumina proton substitution product Inorganic proton conductor particles such as proton-introduced oxides, organic acids containing carboxylic acids, organic acids containing sulfonic acids, organic acids containing phosphonic acids, and appropriate amounts of water may be used in combination.

Further, when the polymer electrolyte membrane is produced, a reinforced solid polymer electrolyte membrane can also be produced by using a porous substrate or a sheet-like fibrous material.
As a method for producing a reinforced solid polymer electrolyte membrane, for example, a liquid composition is impregnated into a porous base material or a sheet-like fibrous material, and the aromatic copolymer is used as a porous base material or A method of filling the pores inside the sheet-like fibrous material, the liquid composition is applied to a porous substrate or a sheet-like fibrous material, and the aromatic copolymer is added to the porous substrate or A method of filling the pores inside the sheet-like fibrous substance, and after forming a film from the liquid composition, the film is laminated on a porous substrate or a sheet-like fibrous substance and hot pressed, Examples thereof include a method of filling the aromatic copolymer into the pores of a porous substrate or a sheet-like fibrous material.

Further, when forming a solid polymer electrolyte membrane having a multilayer structure, a die coat, spray coat, knife coat, roll coat, spin coat, gravure is further applied to the surface of the solid polymer electrolyte membrane obtained by the above-described methods. The composition containing the aromatic copolymer is applied by a known method such as coating, and dried as necessary, or a film formed from the composition containing the aromatic copolymer is described above. For example, the film obtained by the above method may be hot-pressed on the film. The thickness of the polymer layer may be adjusted by adjusting the coating amount. For example, one polymer layer may be thick and the other thin.

The porous substrate is not particularly limited as long as it has a large number of pores or voids penetrating in the thickness direction. For example, organic porous substrates made of various resins, glass, alumina Inorganic porous base materials composed of metal oxides and metals themselves.

The porous substrate may have a large number of through holes penetrating in a direction substantially parallel to the thickness direction.
As such a porous substrate, JP 2008-119662 A, JP 2007-154153 A, JP 8-20660 A, JP 8-20660 A, JP 2006-120368 A, Those disclosed in Japanese Patent Application Laid-Open Nos. 2004-171994 and 2009-64777 can be used.

As the porous substrate used in the present invention, an organic porous substrate is preferable, and specifically, polyolefins such as polytetrafluoroethylene, high molecular weight polyethylene, cross-linked polyethylene, polyethylene and polypropylene, polyimide, polyacrylo What consists of 1 or more types chosen from the group which consists of tolyl, polyamideimide, polyetherimide, polyethersulfone, and glass is preferable. The polyolefin is preferably high molecular weight polyethylene, cross-linked polyethylene, polyethylene or the like.

[Membrane-electrode assembly]
The membrane-electrode assembly according to the present invention is a membrane-electrode assembly comprising the solid polymer electrolyte membrane, a catalyst layer, and a gas diffusion layer. Typically, a catalyst layer for the cathode electrode is provided on one side of the solid polymer electrolyte membrane, and a catalyst layer for the anode electrode is provided on the other side, and each of the catalyst layers on the cathode side and the anode side is further provided. Gas diffusion layers are provided on the cathode side and the anode side, respectively, in contact with the side opposite to the solid polymer electrolyte membrane.

Known gas diffusion layers and catalyst layers can be used without particular limitation.
Specifically, the gas diffusion layer is composed of a porous substrate or a laminated structure of a porous substrate and a microporous layer. When the gas diffusion layer is composed of a laminated structure of a porous substrate and a microporous layer, the microporous layer is provided in contact with the catalyst layer. The gas diffusion layers on the cathode side and the anode side preferably contain a fluoropolymer in order to impart water repellency.

The catalyst layer is composed of a catalyst and an ion exchange resin electrolyte. As the catalyst, a noble metal catalyst such as platinum, palladium, gold, ruthenium or iridium is preferably used. The noble metal catalyst may contain two or more elements such as an alloy or a mixture. As such noble metal catalyst, one supported on high specific surface area carbon fine particles can be used.

The ion exchange resin electrolyte functions as a binder component for binding the carbon carrying the catalyst, and at the anode electrode, efficiently supplies ions generated by the reaction on the catalyst to the solid polymer electrolyte membrane. Then, ions supplied from the solid polymer electrolyte membrane are efficiently supplied to the catalyst.

As the ion exchange resin of the catalyst layer used in the present invention, a polymer having a proton exchange group is preferable in order to improve proton conductivity in the catalyst layer. Proton exchange groups contained in such polymers include sulfonic acid groups, carboxylic acid groups, and phosphoric acid groups, but are not particularly limited. Further, such a polymer having a proton exchange group is also selected without any particular limitation, but a polymer having a proton exchange group composed of a fluoroalkyl ether side chain and a fluoroalkyl main chain, a sulfonic acid group An aromatic hydrocarbon polymer having the same is preferably used. In addition, an aromatic hydrocarbon polymer having a sulfonic acid group constituting the solid polymer electrolyte membrane may be used as an ion-exchange resin, and a polymer containing a fluorine atom having a proton exchange group or ethylene Or other polymers obtained from styrene or the like, copolymers or blends thereof. As such an ion exchange resin electrolyte, a known one can be used without any particular limitation, and for example, Nafion (DuPont, registered trademark), an aromatic hydrocarbon polymer having a sulfonic acid group, or the like can be used without any particular limitation. .

If necessary, the catalyst layer used in the present invention may further include a resin having no carbon fiber or ion exchange group. These resins are preferably resins with high water repellency. For example, fluorine-containing copolymers, silane coupling agents, silicone resins, waxes, polyphosphazenes and the like can be mentioned, and fluorine-containing copolymers are preferred.

[Fuel cell]
The polymer electrolyte fuel cell according to the present invention is characterized by including the membrane-electrode assembly. Specifically, at least one electricity generating part including at least one membrane-electrode assembly and separators located on both sides thereof; a fuel supply part for supplying fuel to the electricity generating part; and an oxidant for the electricity A fuel cell comprising an oxidant supply section for supplying to a generation section, wherein the membrane-electrode assembly is as described above.

As the separator used in the battery of the present invention, those used in ordinary fuel cells can be used. Specifically, carbon type or metal type can be used.

Moreover, as a member constituting the fuel cell, a known member can be used without any particular limitation. The battery of the present invention can be used as a single cell or as a stack in which a plurality of single cells are connected in series. As a stacking method, a known method can be used. Specifically, planar stacking in which single cells are arranged in a plane and bipolar stacking in which single cells are stacked via separators each having a fuel or oxidant flow path formed on the back surface of the separator can be used. .

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. In Examples, “%” means “% by weight” unless otherwise specified.

[Preparation of electrolyte membrane for evaluation]
The copolymer obtained in each Example / Comparative Example was dissolved in an N-methylpyrrolidone / methanol solution, then cast on a PET substrate using an applicator, and 60 ° C. × 30 minutes, 80 ° C. using an oven. × 40 minutes, 120 ° C. × 60 minutes. The dried membrane was immersed in deionized water. After immersion, a film for evaluation was obtained by drying at 50 ° C. for 45 minutes.

[Molecular weight]
The copolymer obtained in each Example / Comparative Example was dissolved in N-methylpyrrolidone buffer solution (hereinafter referred to as NMP buffer solution), and gel permeation chromatography (GPC, TSK-GEL column manufactured by Tosoh Corporation). ALPHA-M type), polystyrene-equivalent number average molecular weight (Mn) and weight average molecular weight (Mw) were determined. The NMP buffer solution was adjusted at a ratio of NMP (3 L) / phosphoric acid (3.3 mL) / lithium bromide (7.83 g).

[Ratio of the amount of phosphonic acid groups and sulfonic acid groups]
It is the ratio of the amount of phosphonic acid groups and sulfonic acid groups present in the entire raw material used in the polymerization reaction of the sulfonated polymer.

[Ion exchange capacity]
The resulting sulfonated polymer was washed with distilled water until the washing water became neutral to remove free remaining acid, and then dried. Thereafter, a predetermined amount is weighed and dissolved in a THF / water mixed solvent, titrated with a standard solution of NaOH using phenolphthalein as an indicator, and the ion exchange capacity (meq / g) is obtained from the neutralization point. It was.

[Measurement of proton conductivity]
The AC resistance was obtained by pressing a platinum wire (f = 0.5 mm) on the surface of a strip-shaped sample film having a width of 5 mm, holding the sample in a constant temperature and humidity device, and measuring AC impedance between the platinum wires. . That is, the impedance at AC 10 kHz was measured in an environment of 85 ° C. and relative humidity 90%. A chemical impedance measurement system manufactured by NF Circuit Design Block Co., Ltd. was used as the resistance measurement device, and JW241 manufactured by Yamato Scientific Co., Ltd. was used as the constant temperature and humidity device. Five platinum wires were pressed at intervals of 5 mm, the distance between the wires was changed to 5 to 20 mm, and the AC resistance was measured. The specific resistance of the membrane was calculated from the line-to-line distance and the resistance gradient, and the proton conductivity was calculated from the reciprocal of the specific resistance.
Specific resistance R (Ω · cm) = 0.5 (cm) × film thickness (cm) × resistance-to-resistance gradient (Ω / cm)

[Fenton test]
A Fenton reagent was prepared so that iron sulfate heptahydrate and iron ion concentration were 2.5 ppm in 3% by weight of hydrogen peroxide. 50 g of Fenton reagent was collected in a 50 ml glass sample tube, a polymer electrolyte membrane cut to 2 cm × 3 cm was added, and after sealing, immersed in a constant temperature water bath at 45 ° C., a 24-hour Fenton test was performed. After the Fenton test, the film was taken out, washed with ion-exchanged water, allowed to stand at 25 ° C. and a relative humidity of 50% for 12 hours, and various physical properties were measured. The weight retention rate in the Fenton test was calculated by the following mathematical formula.
Weight retention (%) in Fenton test = film weight after Fenton test / film weight before Fenton test × 100
Evaluation criteria:
Weight retention of 95% or more ... ○,
More than 50% weight retention and less than 95%… △,
Weight retention 50% or less ... ×
Ion exchange capacity retention rate (%) in Fenton test = ion exchange capacity after Fenton test / ion exchange capacity before Fenton test × 100
Evaluation criteria:
More than 95% ion exchange capacity ...
More than 50% ion exchange capacity and less than 95%… △,
Ion exchange capacity 50% or less… ×

[Hot water test: How to determine swelling shrinkage]
The film was cut into 2.0 cm × 3.0 cm and weighed to obtain a test piece for testing. After conditioning under conditions of 24 ° C. and 50% relative humidity (RH), this film is put into a polycarbonate 250 ml bottle, about 100 ml of distilled water is added thereto, and a pressure cooker tester (manufactured by HIRAYAMA MFS CORP) is used. And PC-242HS) for 24 hours. After completion of the test, each film was taken out from the hot water, the surface water was gently wiped off with Kimwipe, the dimensions were measured, and the swelling rate was determined. The film was conditioned at 24 ° C. and RH 50%, water was distilled off, and the dimensions of the film after the hot water test were measured to determine the shrinkage. The amount of expansion and contraction was determined according to the following formula.
Swelling ratio = (size of 2 cm side when containing water / 2 cm + size of 3 cm side when containing water / 3 cm) × 100/2
Shrinkage rate = (size of 2 cm side when dried / 2 cm + size of 3 cm side when dried / 3 cm) × 100/2
Swelling shrinkage amount = (swelling rate−100) + (100−shrinkage rate)

[Measurement of tensile strength, tensile elongation and elastic modulus]
Measurement of tensile strength, tensile elongation, and elastic modulus was performed according to JIS K7113 (tensile speed: 50 mm / min). However, the elastic modulus was calculated with the distance between marked lines as the distance between chucks. According to JIS K7113, the condition of the sample was adjusted for 48 hours under conditions of a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%. However, the No. 7 dumbbell described in JIS K6251 was used for punching the sample. As the tensile test measurement device, 5543 manufactured by INSTRON was used.

[Yield calculation]
The yield was calculated by yield (%) = (product yield / theoretical production amount) × 100.

<Compound A derived from the structural unit represented by Formula (1)>
<Synthesis Example 1-1>
3,5-Dichlorobenzenesulfonyl chloride (114.65 g, 467 mmol) was added to a solution of neopentyl alcohol (45.30 g, 514 mmol) in pyridine (300 mL) over 15 minutes with stirring. During this time, the reaction temperature was kept at 18-20 ° C. The reaction mixture was stirred for an additional 30 minutes with cooling, then ice-cold 10% HCl (1600 mL) was added. Insoluble components in water were extracted with 700 mL of ethyl acetate, washed twice with 1N HCl (700 mL each), twice with 5% NaHCO ₃ (700 mL each) and dried over MgSO ₄ . The solvent was removed using a rotary dryer and the residue was recrystallized from 500 mL methanol. As a result, pure (purity exceeding 99% by 1H NMR) neopentyl 3,5-dichlorobenzenesulfonate (formula (30-1)) was obtained as glossy colorless crystals. The yield was 105.98 g, and the yield was 76%.

<Synthesis Example 1-2>
2,5-Dichlorobenzenesulfonyl chloride (114.65 g, 467 mmol) was added to a solution of neopentyl alcohol (45.30 g, 514 mmol) in pyridine (300 mL) over 15 minutes with little stirring. During this time, the reaction temperature was kept at 18-20 ° C. The reaction mixture was stirred for an additional 30 minutes with cooling, then ice-cold 10% HCl (1600 mL) was added. Insoluble components in water were extracted with 700 mL of ethyl acetate, washed twice with 1N HCl (700 mL each), twice with 5% NaHCO ₃ (700 mL each) and dried over MgSO ₄ . The solvent was removed using a rotary dryer and the residue was recrystallized from 500 mL methanol. As a result, pure (purity exceeding 99% by 1H-NMR) neopentyl 2,5-dichlorobenzenesulfonate (formula (30-2)) was obtained as glossy colorless crystals. The yield was 99.93 g, and the yield was 72%.

<Synthesis example of compound B derived from structural unit having phosphonic acid group>
<Synthesis Example 2-1>
In a 2 L three-necked flask equipped with a stirring blade, a thermometer, and a nitrogen introduction tube, 134.0 g (0.91 mol) of 1,4-dichlorobenzene, 100.0 g (0.46 mol) of 3-bromobenzoyl chloride, 121 aluminum chloride 121 0.5 g (0.91 mol) was taken and stirred at 135 ° C. for 4 hours. After completion of the reaction, the reaction solution was dropped into ice water and extracted from toluene. The mixture was neutralized with 1% aqueous sodium hydrogen carbonate solution, washed with saturated brine, and concentrated. The following formula (30-3) was obtained by recrystallization from hexane. The yield was 96.1 g.

(30-3) 33.0 g (0.1 mol), 2-hydroxy-1,3,2-dioxaphosphorinane 13.43 g in a 1 L three-necked flask equipped with a stirring blade, thermometer, and nitrogen inlet tube (0.11 mol), 5.78 g (5 mmol) of tetrakis (triphenylphosphino) palladium and 11.13 g (0.11 mol) of triethylamine were taken and stirred at 80 ° C. for 3 hours. After completion of the reaction, the precipitated salt was removed by filtration, and the solvent was concentrated. Purification by recrystallization from toluene gave the following formula (30-4). Yield 20.4g.

Take 32.4 g (0.2 mol) of 3,5-dichloroaniline in a 1 L four-necked flask equipped with a stirring blade, thermometer, and nitrogen inlet tube, and disperse in 125 mL of concentrated hydrochloric acid and 125 mL of water. Cooled down. An aqueous solution in which 13.8 g (0.2 mol) of sodium nitrite was dissolved in 80 mL of water was dropped while maintaining the temperature at −5 ° C. or lower. After completion of the dropping, stirring was continued at −5 ° C. or lower for 30 minutes, and then dropwise added at 0 ° C. to an aqueous solution in which 60 g (0.4 mol) of sodium iodide was dissolved in 100 mL of water. After gas evolution ceased, the reaction solution was diluted with water. Sodium sulfite was added until the dark coloration due to free iodine disappeared. Purification by steam distillation and recrystallization from ethanol gave 29.5 g of colorless crystals of 1-iodo-3,5-dichlorobenzene, which was the target product.

Reference 1: Adv. Mater. 2007, 19, 3317-3321. In a 500 mL three-necked flask equipped with a stirring blade, a thermometer, and a nitrogen introduction tube, 27.29 g (0.10 mol) of 1-iodo-3,5-dichlorobenzene obtained above, 2-hydroxy-1,3 , 2-dioxaphosphorinane 13.43 g (0.11 mol), tetrakis (triphenylphosphino) palladium 5.78 g (5 mmol), triethylamine 11.13 g (0.11 mol), toluene 150 mL were taken at 80 ° C. Stir for 5 hours. After completion of the reaction, the precipitated salt was removed by filtration, and the solvent was concentrated. Purification was carried out by recrystallization from toluene to obtain the compound represented by the above formula (30-5) as the target product. The yield was 20.3g.

In a 500 mL three-necked flask equipped with a stirring blade, a thermometer, and a nitrogen inlet tube, 22.59 g (0.10 mol) of 1-bromo-2,5-dichlorobenzene, 2-hydroxy-1,3,2-dioxa Phosphorinan (13.43 g, 0.11 mol), tetrakis (triphenylphosphino) palladium (5.78 g, 5 mmol), triethylamine (11.13 g, 0.11 mol), and toluene (150 mL) were taken and stirred at 80 ° C. for 5 hours. After completion of the reaction, the precipitated salt was removed by filtration, and the solvent was concentrated. Purification was performed by recrystallization from toluene to obtain a compound represented by the above formula (30-6), which was the target product. The yield was 19.2g.

<Synthesis of Compound C Derived from Structural Unit Having Aromatic Structure>
<Synthesis Example 3-1>
To a 1 L three-necked flask equipped with a stirrer, thermometer, Dean-stark tube, nitrogen inlet tube, and condenser tube, 154.8 g (0.9 mol) of 2,6-dichlorobenzonitrile and 2,2-bis (4-hydroxy) were added. Phenyl) -1,1,1,3,3,3-hexafluoropropane (269.0 g, 0.8 mol) and potassium carbonate (143.7 g, 1.04 mol) were weighed. After substitution with nitrogen, 1020 mL of sulfolane and 510 mL of toluene were added and stirred. The reaction solution was heated to reflux at 150 ° C. in an oil bath. Water produced by the reaction was trapped in a Dean-stark tube. After 3 hours, when almost no water was observed, toluene was removed from the Dean-stark tube out of the system. The reaction temperature was gradually raised to 200 ° C. and stirring was continued for 3 hours. Then, 51.6 g (0.3 mol) of 2,6-dichlorobenzonitrile was added, and the reaction was further continued for 5 hours.

The reaction solution was allowed to cool and then diluted by adding 250 mL of toluene. Inorganic salts insoluble in the reaction solution were filtered, and the filtrate was poured into 8 L of methanol to precipitate the product. The precipitated product was filtered and dried, then dissolved in 500 mL of tetrahydrofuran, and poured into 5 L of methanol for reprecipitation. The precipitated white powder was filtered and dried to obtain 258 g of the desired product. Mn measured by GPC was 8,200. It was confirmed that the obtained compound was an oligomer represented by formula (40-1). In formula (40-1), u is 18.4 (where u is an average value calculated from the number average molecular weight (Mn)).

<Synthesis Example 3-2>
To a 1 L three-necked flask equipped with a stirrer, thermometer, Dean-stark tube, nitrogen introduction tube, and condenser tube, 90.1 g (0.52 mol) of 2,6-dichlorobenzonitrile and 2,5-di-tert-butyl Weighed 26.6 g (0.12 mol) of hydroquinone, 59.4 g (0.36 mol) of 2-tert-butylhydroquinone, and 85.6 g (0.62 mol) of potassium carbonate. After substitution with nitrogen, 600 mL of sulfolane and 300 mL of toluene were added and stirred. The reaction solution was heated to reflux at 150 ° C. in an oil bath. Water produced by the reaction was trapped in a Dean-stark tube. After 3 hours, when almost no water was observed, toluene was removed from the Dean-stark tube out of the system. The reaction temperature was gradually raised from 180 to 190 ° C., and stirring was continued for 3 hours. Then, 24.6 g (0.14 mol) of 2,6-dichlorobenzonitrile was added, and the reaction was further continued for 5 hours.

The reaction solution was allowed to cool and then coagulated in 2401 mL of a methanol / 4 wt% (5/1 (volume ratio)) sulfuric acid solution. The precipitated product was filtered and stirred in 2401 mL of water at 55 ° C. for 1 hour. After filtration, the mixture was again stirred in 2401 mL of water at 55 ° C. for 1 hour. After filtration, the mixture was stirred in methanol (2401 mL) at 55 ° C. for 1 hour, filtered, and again stirred in methanol (2401 mL) at 55 ° C. for 1 hour and filtered. After air drying, it was vacuum-dried at 80 ° C. to obtain 125 g (yield 90%) of the desired product.
Mn measured by GPC was 7,000. It was confirmed that the obtained compound was an oligomer represented by formula (40-2). In formula (40-2), q is 6.1 and r is 18.3 (where q and r are average values calculated from the number average molecular weight (Mn)).

<Synthesis Example 3-3>
2,6.6 g (0.12 mol) of 2,5-di-tert-butylhydroquinone, 59.4 g (0.36 mol) of 2-tert-butylhydroquinone, 26.6 g (0,0) of 2,5-di-tert-butylhydroquinone (0 .12 mol), 47.5 g (0.29 mol) of 2-tert-butylhydroquinone, 24.0 g of 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane ( Except for the change to 0.07 mol), an oligomer represented by the following (40-3) was obtained in the same manner as in Synthesis Example 3-2. The Mn measured by GPC was 7,200. In formula (40-3), s is 5.8, t is 14.0, u is 3.4 (where s, t, and u are average values calculated from the number average molecular weight (Mn)). .)

<Synthesis Example 3-4>
Into a 1 L three-necked flask equipped with a stirrer, thermometer, Dean-stark tube, nitrogen introduction tube, and cooling tube, 149.3 g (0.52 mol) of bis (4-chlorophenyl) sulfone, bis (4-hydroxyphenyl) sulfone 120 0.1 g (0.48 mol) and potassium carbonate 85.6 g (0.62 mol) were weighed. After substitution with nitrogen, 700 mL of sulfolane and 350 mL of toluene were added and stirred. The reaction solution was heated to reflux at 150 ° C. in an oil bath. Water produced by the reaction was trapped in a Dean-stark tube. After 3 hours, when almost no water was observed, toluene was removed from the Dean-stark tube out of the system. The reaction temperature was gradually raised from 180 to 190 ° C. and stirring was continued for 3 hours. Then, 40.2 g (0.14 mol) of bis (4-chlorophenyl) sulfone was added, and the reaction was further continued for 5 hours.

The reaction solution was allowed to cool and then coagulated in 2400 mL of a methanol / 4 wt% (5/1 (volume ratio)) sulfuric acid solution. The precipitated product was filtered and stirred in 2400 mL of water at 55 ° C. for 1 hour. After filtration, the mixture was again stirred in 2400 mL of water at 55 ° C. for 1 hour. After filtration, the mixture was stirred in methanol (2401 mL) at 55 ° C. for 1 hour, filtered, and again stirred in methanol (2400 mL) at 55 ° C. for 1 hour and filtered. After air drying, it was vacuum dried at 80 ° C. to obtain 187.6 g (yield 80%) of the target product. The Mn measured by GPC was 8,500. It was confirmed that the obtained compound was an oligomer represented by formula (40-4). In formula (40-4), u is 35.5 (where u is an average value calculated from the number average molecular weight (Mn)).

[Example 1]
28.18 g (94.8 mmol) of the compound represented by (30-1) above, 1.09 g (2.93 mmol) of the compound represented by (30-4) above, and (40-1) above Of 18.45 g (2.25 mmol) of the compound to be obtained, 1.96 g (3.0 mmol) of bis (triphenylphosphine) nickel dichloride, 2.36 g (9.0 mmol) of triphenylphosphine, 11.77 g (180 mmol) of zinc 160 mL of dry dimethylacetamide (DMAc) was added under nitrogen.

The reaction system was heated with stirring (finally heated to 79 ° C.) and reacted for 3 hours. An increase in viscosity in the system was observed during the reaction. The polymerization reaction solution was diluted with 330 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid.

39.4 g (453.1 mmol) of lithium bromide was added to the filtrate, and the mixture was reacted at an internal temperature of 120 ° C. for 7 hours under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature, poured into 4.3 L of water and solidified. The coagulum was immersed in acetone, filtered and washed. The washed product was washed while being stirred with 6500 g of 1N sulfuric acid. After filtration, the product was washed with ion exchanged water until the pH of the washing solution became 5 or higher. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1. The obtained polymer was represented by the following general formula (50-1). In formula (50-1), x, y, and z each represent a composition ratio, x is 94.8 mol%, y is 2.9 mol%, z is 2.3 mol%, and u is 18. 4.

[Example 2]
27.31 g (91.9 mmol) of the compound represented by the above (30-1) is 27.31 g (91.9 mmol), and 1.09 g (2.93 mmol) of the compound represented by the above (30-4) is 2 The following general formula (50-2) was changed in the same manner as in Example 1 except that .18 g (5.87 mmol) and lithium bromide 39.4 g (453.1 mmol) were changed to 40.5 g (466.3 mmol). Obtained. In formula (50-2), x, y, and z each represent a composition ratio, x is 91.9 mol%, y is 5.9 mol%, z is 2.3 mol%, and u is 18. 4. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 3]
28.08 g (94.5 mmol) of the compound represented by the above (30-1) is 28.08 g (94.5 mmol), and 1.09 g (2.93 mmol) of the compound represented by the above (30-4) is 1 0.08 g (2.92 mmol), 18.45 g (2.25 mmol) of the compound represented by (40-1) above, 18.20 g (2.60 mmol) of the compound represented by (40-2) above, bromide The following general formula (50-3) was obtained in the same manner as in Example 1 except that 39.4 g (453.1 mmol) of lithium was changed to 39.2 g (451.4 mmol). In the formula (50-3), x, y, and z each represent a composition ratio, x is 94.5 mol%, y is 2.9 mol%, z is 2.6 mol%, and r is 18. 3, q is 6.1. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 4]
28.08 g (94.5 mmol) of the compound represented by the above (30-1) is 28.08 g (94.5 mmol), and 1.09 g (2.93 mmol) of the compound represented by the above (30-4) is 1 0.08 g (2.92 mmol) 18.45 g (2.25 mmol) of the compound represented by (40-1) above, 18.72 g (2.60 mmol) of the compound represented by (40-2) above, lithium bromide In the formula (50-3), the following general formula (50-4) was obtained in the same manner as in Example 1 except that 39.4 g (453.1 mmol) was changed to 39.2 g (451.4 mmol). , Y and z each represent a composition ratio, x is 94.5 mol%, y is 2.9 mol%, z is 2.6 mol%, s is 5.8, t is 14.0, u Is 3.4.
As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 5]
The same as Example 1 except that 28.18 g (94.8 mmol) of the compound represented by the above (30-1) was changed to 28.18 g (94.8 mmol) of the compound represented by the above (30-2). The following general formula (50-5) was obtained. In the formula (50-5), x, y, and z each represent a composition ratio, x is 94.8 mol%, y is 2.9 mol%, z is 2.3 mol%, and u is 18. 4. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 6]
The same as Example 2 except that 27.31 g (91.9 mmol) of the compound represented by (30-1) was changed to 27.31 g (91.9 mmol) of the compound represented by (30-2). The following general formula (50-6) was obtained. In formula (50-6), x, y, and z each represent a composition ratio, x is 91.9 mol%, y is 5.9 mol%, z is 2.3 mol%, and u is 18. 4. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 7]
The same as Example 3 except that 28.08 g (94.5 mmol) of the compound represented by (30-1) was changed to 28.08 g (94.5 mmol) of the compound represented by (30-2). Thus, the following general formula (50-7) was obtained. In the formula (50-7), x, y, and z each represent a composition ratio, x is 94.5 mol%, y is 2.9 mol%, z is 2.6 mol%, and r is 18. 3, q is 6.1. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 8]
The same as Example 4 except that 28.08 g (94.5 mmol) of the compound represented by the above (30-1) was changed to 28.08 g (94.5 mmol) of the compound represented by the above (30-2). Thus, the following general formula (50-8) was obtained. In the formula (50-8), x, y and z each represent a composition ratio, x is 94.5 mol%, y is 2.9 mol%, z is 2.6 mol%, and s is 5. 8, t is 14.0, and u is 3.4. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 9]
Except for changing 18.45 g (2.25 mmol) of the compound represented by (40-1) to 19.13 g (2.25 mmol) of the compound represented by (40-4), Example 1 and Similarly, the following general formula (50-9) was obtained. In the formula (50-9), x, y, and z each represent a composition ratio, x is 94.8 mol%, y is 2.9 mol%, z is 2.3 mol%, and u is 35. 5. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 10]
The same as Example 9 except that 28.18 g (94.8 mmol) of the compound represented by the above (30-1) was changed to 28.18 g (94.8 mmol) of the compound represented by the above (30-2). The following general formula (50-10) was obtained. In the formula (50-9), x, y, and z each represent a composition ratio, x is 94.8 mol%, y is 2.9 mol%, z is 2.3 mol%, and u is 35. 5. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

<Synthesis of sulfonated block polymer>
[Example 11]
27.39 g (92.15 mmol) of the compound represented by (30-1), 1.30 g (4.85 mmol) of the compound represented by (30-5), and (40-2) In a mixture of 21.00 g (3.00 mmol) of the compound, 2.62 g (4.00 mmol) of bis (triphenylphosphine) nickel dichloride, 3.15 g (12.00 mmol) of triphenylphosphine, and 15.69 g (240 mmol) of zinc 150 mL of dried dimethylacetamide (DMAc) was added under nitrogen.

The reaction system was heated with stirring (finally heated to 79 ° C.) and reacted for 3 hours. An increase in viscosity in the system was observed during the reaction. The polymerization reaction solution was diluted with 240 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid.

To the filtrate, 39.81 g (458 mmol) of lithium bromide was added and reacted at an internal temperature of 100 ° C. for 7 hours in a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature, poured into 3.4 L of water and solidified. The coagulum was immersed in acetone, filtered and washed. The washed product was washed with stirring with 6.0 kg of 1N sulfuric acid. After filtration, the product was washed with ion exchanged water until the pH of the washing solution became 5 or higher. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1. The obtained polymer was a polymer having a structure represented by the following formula (50-11). In the formula (50-11), x, y, and z each represent a composition ratio, x is 92.2 mol%, y is 4.9 mol%, z is 3.0 mol%, and r is 18. 3, q is 6.1.

[Example 12]
27.53 g (92.64 mmol) of the compound represented by (30-2) above, 1.30 g (4.88 mmol) of the compound represented by (30-5) above, represented by (40-4) above A polymer represented by the following formula (50-12) was obtained in the same manner as in Example 1, except that the compound was changed to 21.08 g (2.48 mmol) and lithium bromide 40.02 g (461 mmol). In the formula (50-12), x, y and z each represent a composition ratio, x is 92.6 mol%, y is 4.9 mol%, z is 2.5 mol%, and u is 35. 5. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 13]
27.47 g (92.44 mmol) of the compound represented by (30-1) above, 1.30 g (4.87 mmol) of the compound represented by (30-6) above, represented by (40-1) above A polymer represented by the following formula (50-13) was obtained in the same manner as in Example 1 except that the compound was changed to 21.06 g (2.70 mmol) and lithium bromide 39.93 g (460 mmol). In the formula (50-13), x, y and z each represent a composition ratio, x is 92.4 mol%, y is 4.9 mol%, z is 2.7 mol%, and u is 18. 4. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 14]
27.53 g (92.64 mmol) of the compound represented by (30-2) above, 1.30 g (4.88 mmol) of the compound represented by (30-6) above, represented by (40-4) above A polymer represented by the following formula (50-14) was obtained in the same manner as in Example 1 except that the compound was changed to 21.08 g (2.48 mmol) and lithium bromide 40.02 g (461 mmol). In the formula (50-14), x, y and z each represent a composition ratio, x is 92.6 mol%, y is 4.9 mol%, z is 2.5 mol%, and u is 35. 5. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Example 15]
21.62 g (72.75 mmol) of the compound represented by the above (30-1), 6.48 g (24.25 mmol) of the compound represented by the above (30-5), 47.39 g (546 mmol) of lithium bromide A polymer represented by the following formula (50-15) was obtained in the same manner as in Example 11 except for changing to In the formula (50-15), x, y and z each represent a composition ratio, x is 72.8 mol%, y is 24.3 mol%, z is 3.0 mol%, and r is 18. 3, q is 6.1. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1.

[Comparative Example 1]
29.05 g (97.8 mmol) of the compound represented by the above (30-1), 18.45 g (2.25 mmol) of the compound represented by the above (40-1), bis (triphenylphosphine) nickel dichloride 1 In a mixture of .96 g (3.0 mmol), triphenylphosphine 2.36 g (9.0 mmol), and zinc 11.77 g (180 mmol), 160 mL of dried dimethylacetamide (DMAc) was added under nitrogen.

Lithium bromide (25.5 g, 293.3 mmol) was added to the filtrate, and the mixture was reacted at an internal temperature of 120 ° C. for 7 hours under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature, poured into 4.3 L of water and solidified.
The coagulum was immersed in acetone, filtered and washed. The washed product was washed while being stirred with 6500 g of 1N sulfuric acid. After filtration, the product was washed with ion exchanged water until the pH of the washing solution became 5 or higher. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1. The obtained polymer was represented by the following general formula (60-1). In formula (60-1), x and z each represent a composition ratio, x is 97.8 mol%, z is 2.3 mol%, and u is 18.4.

[Comparative Example 2]
28.95 g (97.4 mmol) of the compound represented by the above (30-1), 18.2 g (2.6 mmol) of the compound represented by the above (40-2), bis (triphenylphosphine) nickel dichloride 1 In a mixture of .96 g (3.0 mmol), triphenylphosphine 2.36 g (9.0 mmol), and zinc 11.77 g (180 mmol), 160 mL of dried dimethylacetamide (DMAc) was added under nitrogen.

Lithium bromide (25.4 g, 292.2 mmol) was added to the filtrate, and the mixture was reacted at an internal temperature of 120 ° C. for 7 hours under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature, poured into 4.3 L of water and solidified.
The coagulum was immersed in acetone, filtered and washed. The washed product was washed while being stirred with 6500 g of 1N sulfuric acid. After filtration, the product was washed with ion exchanged water until the pH of the washing solution became 5 or higher. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1. The obtained polymer was represented by the following general formula (60-2). In formula (60-2), x and z each represent a composition ratio, x is 97.4 mol%, z is 2.6 mol%, r is 18.3, and q is 6.1.

[Comparative Example 3]
28.95 g (97.4 mmol) of the compound represented by (30-2) above, 18.7 g (2.6 mmol) of the compound represented by (40-3) above, bis (triphenylphosphine) nickel dichloride 1 In a mixture of .96 g (3.0 mmol), triphenylphosphine 2.36 g (9.0 mmol), and zinc 11.77 g (180 mmol), 160 mL of dried dimethylacetamide (DMAc) was added under nitrogen.

Lithium bromide (25.4 g, 292.2 mmol) was added to the filtrate, and the mixture was reacted at an internal temperature of 120 ° C. for 7 hours under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature, poured into 4.3 L of water and solidified. The coagulum was immersed in acetone, filtered and washed. The washed product was washed while being stirred with 6500 g of 1N sulfuric acid. After filtration, the product was washed with ion exchanged water until the pH of the washing solution became 5 or higher. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1. The obtained polymer was represented by the following general formula (60-3). In the formula (60-3), x and z each represent a composition ratio, x is 97.4 mol%, z is 2.6 mol%, s is 5.8, t is 14.0, u is 3.4.

[Comparative Example 4]
29.05 g (97.8 mmol) of the compound represented by (30-2) above, 19.13 g (2.3 mmol) of the compound represented by (40-4) above, bis (triphenylphosphine) nickel dichloride 1 In a mixture of .96 g (3.0 mmol), triphenylphosphine 2.36 g (9.0 mmol), and zinc 11.77 g (180 mmol), 160 mL of dried dimethylacetamide (DMAc) was added under nitrogen.

Lithium bromide (25.5 g, 293.3 mmol) was added to the filtrate, and the mixture was reacted at an internal temperature of 120 ° C. for 7 hours under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature, poured into 4.3 L of water and solidified. The coagulum was immersed in acetone, filtered and washed. The washed product was washed while being stirred with 6500 g of 1N sulfuric acid. After filtration, the product was washed with ion exchanged water until the pH of the washing solution became 5 or higher. As a result of measuring the molecular weight of the obtained polymer by GPC, the ion exchange capacity is shown in Table 1. The obtained polymer was represented by the following general formula (60-4). In the formula (60-3), x and z each represent a composition ratio, x is 97.8 mol%, z is 2.3 mol%, and u is 35.5.

As shown in Table 1, radical resistance could be improved without impairing proton conductivity by simultaneously using a structural unit having a specific sulfonic acid group and a structural unit having a phosphonic acid group.

Claims

An aromatic copolymer comprising a structural unit represented by the following formula (1) and a structural unit represented by the following formula (4).

(In the above formula (1), each R 1 is independently a halogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms, a represents an integer of 0 to 3, and k represents an integer of 1 to 4. However, a + k ≦ 4, and a plurality of R 1 may be the same or different.

(In Formula (4), each E independently represents at least one structure selected from the group consisting of —CO—, —SO 2 —, —SO—, —CONH—, and —COO— groups, Ar 31 , Ar 32 , and Ar 33 are each independently a divalent or trivalent organic group having a benzene ring, a naphthalene ring or a nitrogen-containing heterocyclic ring, or a hydrogen atom partially or entirely substituted with a fluorine atom. An organic group of
R 31 is at least one selected from the group consisting of a direct bond, —O (CH 2 ) p —, —O (CF 2 ) p —, — (CH 2 ) p —, and — (CF 2 ) p —. (P represents an integer of 1 to 12). e represents an integer of 0 to 10, f represents an integer of 1 to 5, and g represents an integer of 0 to 4. )
The aromatic copolymer according to claim 1, wherein at least two structural units represented by the formula (1) are continuous.
The number ratio of phosphonic acid groups and sulfonic acid groups contained in the aromatic copolymer is (phosphonic acid group / (phosphonic acid group + sulfonic acid group)) in the range of 0.001 to 0.5. The aromatic copolymer according to claim 1 or 2, characterized in that:
A polymer electrolyte comprising the aromatic copolymer according to any one of claims 1 to 3.
A solid polymer electrolyte membrane comprising the aromatic copolymer according to any one of claims 1 to 4.
6. A membrane-electrode assembly comprising the polymer electrolyte membrane according to claim 5 and a catalyst layer and a gas diffusion layer in contact with both sides of the polymer electrolyte membrane.
A polymer electrolyte fuel cell comprising the membrane-electrode assembly according to claim 6.