JP2007191694A - Copolymer, polymer electrolyte, and use thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copolymer, which can be synthesized relatively easily, and from which a membrane material having practical proton conductivity and excellent water resistance for a fuel cell can be obtained; and to provide a fuel cell using the copolymer. <P>SOLUTION: [1] The copolymer is prepared by mixing and polycondensating the following monomers (A), (B), (C) and (D). (A) is a monomer having two leaving groups and at least one acid group in its molecule; (B) is a monomer having two nucleophilic groups and at least one acid group in its molecule; (C) is a monomer having two leaving groups and substantially not having any acid group in its molecule; and (D) is a monomer having two nucleophilic groups and substantially not having any acid group in its molecule. [2] A polymer electrolyte includes the copolymer [1], and a polymer electrolyte membrane includes the polymer electrolyte. [3] A fuel cell includes the polymer electrolyte membrane [2]. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a copolymer, a polymer electrolyte, and a use thereof suitably used as a diaphragm material for a battery, particularly a fuel cell.

A polymer electrolyte having proton conductivity is used as a diaphragm of an electrochemical device such as a primary battery, a secondary battery, or a solid polymer fuel cell. For example, a polymer electrolyte containing a perfluoroalkane polymer having a perfluoroalkylsulfonic acid group as a super strong acid in the side chain, such as Nafion (a registered trademark of DuPont), as an active ingredient is used for a fuel cell. When used as a diaphragm material, it has been used mainly because of its excellent power generation characteristics. However, problems have been pointed out such as this type of material being very expensive, low heat resistance, low film strength, and impractical without some reinforcement.

Under such circumstances, development of inexpensive and excellent polymer electrolytes that can replace the polymer electrolytes has recently been activated.
For example, a block copolymer having a segment in which a sulfonic acid group is not substantially introduced and a segment in which a sulfonic acid group is introduced, wherein the former segment is made of polyethersulfone and the latter segment is diphenylsulfone and A block copolymer which is a condensate with a biphenol having a sulfonic acid group has been proposed (Patent Document 1).
On the other hand, a so-called random copolymer in which acid groups are randomly distributed in the polymer chain with respect to the block copolymer has been studied, and one kind of monomer having a sulfonic acid group introduced therein, Random copolymers (for example, refer to Patent Documents 2 to 5) with monomers into which a sulfonic acid group has not been introduced, and random copolymers obtained by sulfonating a polyethersulfone copolymer (for example, refer to Patent Document 6) Has been proposed.

JP 2003-031232 A (Claims) Japanese translation of PCT publication No. 2004-509224 (claims, paragraph [0047]) JP-T-2006-523258 (paragraphs [0013] to [0018]) US 2002/0091225 (paragraphs [0011] to [0028]) JP 2004-149779 A (Example) JP 10-021943 A (Example)

The block copolymer disclosed in Patent Document 1 is prepared by previously synthesizing either a segment in which a sulfonic acid group is not substantially introduced or a segment in which a sulfonic acid group is introduced. There is a problem in that the synthesis itself is complicated because it requires copolymerization with a monomer that can be formed, or after the polymers that can form the above-mentioned segments are separately synthesized and then further coupled together.

On the other hand, the random copolymers disclosed in Patent Documents 2 to 6 are relatively easy to synthesize compared with the block copolymer, but have a practical proton conductivity as a battery diaphragm material. When trying to obtain, the water absorption rate of the random copolymer is increased, and the obtained diaphragm has a problem that mechanical strength is lowered due to a large dimensional change caused by water generated during operation of the fuel cell. In particular, as a result of the study by the present inventors, the polymer electrolyte composed of the random copolymer disclosed so far has a significantly large water absorption for hot water at about 100 ° C. When used for an electrolyte membrane), the polymer electrolyte membrane itself easily absorbs and deforms due to heat generated by power generation, and it is difficult to maintain its shape.
An object of the present invention is to provide a fuel cell member excellent in practical proton conductivity and water resistance, particularly a good separation material that can be manufactured relatively easily and is excellent in water resistance. The present invention provides a polymer electrolyte and a fuel cell having a stable power generation performance using the polymer electrolyte.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have completed the present invention.

That is, the present invention
[1] A copolymer obtained by mixing and condensing monomers represented by the following (A), (B), (C) and (D): (A) having two leaving groups in the molecule; A monomer having at least one acid group (B) a monomer having two nucleophilic groups in the molecule and a monomer having at least one acid group (C) having two leaving groups in the molecule, Monomer not having acid group (D) A monomer having two nucleophilic groups in the molecule and substantially having no acid group is provided.
Here, the nucleophilic group represents a group having nucleophilicity, which acts on the atom to which the leaving group is bonded, and can form a new covalent bond with the elimination of the leaving group. It is.
In the copolymer of the present invention, the structural unit (A ′) derived from (A) is derived from the structural unit (B ′) derived from (B) and / or (D). Adjacent to the structural unit (D ′), and similarly the structural unit (B ′) is adjacent to the structural unit (A ′) and / or the structural unit (C ′) derived from (C), and the structural unit (C ′) is adjacent to the structural unit (B ′) and / or the structural unit (D ′), and the structural unit (D ′) is adjacent to the structural unit (A ′) and / or the structural unit (C ′). And a copolymer in which structural units (A ′), (B ′), (C ′) and (D ′) are arranged in the polymer chain.

（式中、ｋは０、１又は２を表し、Ａｒ¹、Ａｒ²は互いに独立に２価の芳香族基を表し、ｋが２の場合は、２つのＡｒ²は互いに同じでも、異なっていてもよく、ここで、これらの２価の芳香族基は、置換基を有することもある炭素数１〜１０のアルキル基、置換基を有することもある炭素数１〜１０のアルコキシ基、置換基を有することもある炭素数６〜１０のアリール基、置換基を有することもある炭素数６〜１０のアリールオキシ基、フルオロ基、ニトロ基又はベンゾイル基で置換されていてもよい。ｋが０である場合はＡｒ¹が、ｋが１以上である場合は、Ａｒ¹、Ａｒ²のいずれかが、少なくとも一つの酸基を有する。Ｘ¹は脱離基を表し、ここで脱離基はフルオロ基、クロロ基、ニトロ基又はトリフルオロメタンスルホニルオキシ基のいずれかを表し、２つのＸ¹は互いに同じでも、異なっていてもよい。Ｚ¹は下記の群から選ばれる基であり、ｋが２の場合、２つのＺ¹は互いに同じでも、異なっていてもよい。）

［３］前記（Ｂ）が、下記式（２）で示される化合物を含む［１］又は［２］の共重合体

（式中、ｊは０、１又は２を表し、Ａｒ³、Ａｒ⁴は互いに独立に２価の芳香族基を表し、ｊが２の場合、２つのＡｒ⁴は互いに同じでも、異なっていてもよく、ここで、これらの２価の芳香族基は、置換基を有することもある炭素数１〜１０のアルキル基、置換基を有することもある炭素数１〜１０のアルコキシ基、置換基を有することもある炭素数６〜１０のアリール基、または置換基を有することもある炭素数６〜１０のアリールオキシ基で置換されていてもよい。ｊが０である場合はＡｒ³が、ｊが１以上である場合は、Ａｒ³、Ａｒ⁴のいずれかが、少なくとも一つの酸基を有する。Ｙ¹は、フェノール性水酸基、チオール基又はアミノ基を表し、２つのＹ¹は、互いに同じでも、異なっていてもよい。Ｑ¹は直接結合、及び下記の群から選ばれる基を表し、ｊが２の場合、２つのＱ¹は互いに同じでも、異なっていてもよい。）

［４］前記（Ｃ）が、下記式（３）で示される化合物を含む［１］〜［３］いずれかの共重合体

（式中、ｍは０、１又は２を表し、Ａｒ⁵、Ａｒ⁶は互いに独立に２価の芳香族基を表し、ｍが２の場合、２つのＡｒ⁶は互いに同じでも、異なっていてもよく、ここで、これらの２価の芳香族基は、置換基を有することもある炭素数１〜１０のアルキル基、置換基を有することもある炭素数１〜１０のアルコキシ基、置換基を有することもある炭素数６〜１０のアリール基、置換基を有することもある炭素数６〜１０のアリールオキシ基、フルオロ基、ニトロ基又はベンゾイル基で置換されていてもよい。Ｘ²は脱離基を表し、ここで脱離基はフルオロ基、クロロ基、ニトロ基又はトリフルオロメタンスルホニルオキシ基から選ばれ、２つのＸ²は互いに同じでも、異なっていてもよい。Ｚ²は下記の群から選ばれ、ｍが２の場合、２つのＺ²は互いに同じでも、異なっていてもよい。）

［５］前記（Ｄ）が、下記式（４）で示される化合物を含む［１］〜［４］いずれかの共重合体

（式中、ｎは０,１又は２を表し、Ａｒ⁷、Ａｒ⁸は互いに独立に２価の芳香族基を表し、ｎが２の場合、２つのＡｒ⁸は互いに同じでも、異なっていてもよく、ここで、これらの２価の芳香族基は、置換基を有することもある炭素数１〜１０のアルキル基、置換基を有することもある炭素数１〜１０のアルコキシ基、置換基を有することもある炭素数６〜１０のアリール基、または置換基を有することもある炭素数６〜１０のアリールオキシ基で置換されていてもよい。Ｙ²はフェノール性水酸基、チオール基又はアミノ基を表し、２つのＹ²は互いに同じでも、異なっていてもよい。Ｑ²は直接結合、または下記の群から選ばれる基であり、ｎが２の場合、２つのＱ²は互いに同じでも、異なっていてもよい。）
［６］酸基が、強酸基又は超強酸基であることを特徴とする、［１］〜［５］いずれかの共重合体
［７］イオン交換容量が、０．１ｍｅｑ／ｇ〜４．０ｍｅｑ／ｇであることを特徴とする［１］〜［６］いずれかの共重合体
［８］共重合体中、酸基が導入された構造単位と、酸基が実質的に導入されていない構造単位の重量組成比が、［酸基が導入された構造単位］：［酸基が実質的に導入されていない構造単位］で表して、３：９７〜７０：３０であることを特徴とする［１］〜［７］いずれかの共重合体 Furthermore, this invention provides the copolymer shown by following [2]-[8].
[2] The copolymer of [1], wherein (A) comprises a compound represented by the following formula (1)

(In the formula, k represents 0, 1 or 2, Ar ¹ and Ar ² each independently represents a divalent aromatic group, and when k is 2, two Ar ^{2 s} are the same as or different from each other. Here, these divalent aromatic groups may have a C1-C10 alkyl group which may have a substituent, a C1-C10 alkoxy group which may have a substituent, a substitution The aryl group having 6 to 10 carbon atoms which may have a group, the aryloxy group having 6 to 10 carbon atoms which may have a substituent, a fluoro group, a nitro group or a benzoyl group may be substituted. If it is 0, the Ar ^1, if k is 1 or more, one of Ar ^1, Ar ² is, .X ¹ having at least one acid group represents a leaving group, where the leaving group Is fluoro, chloro, nitro or trifluoromethanesulfonyloxy Any one of the groups, and two X ¹ may be the same or different from each other, Z ¹ is a group selected from the following group, and when k is 2, the two Z ¹ may be the same as each other, May be different.)

[3] The copolymer of [1] or [2], wherein (B) comprises a compound represented by the following formula (2)

(Wherein j represents 0, 1 or 2, Ar ³ and Ar ⁴ each independently represent a divalent aromatic group, and when j is 2, two Ar ^{4 s} may be the same or different from each other. Here, these divalent aromatic groups are an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, and a substituent. Or an aryloxy group having 6 to 10 carbon atoms which may have a substituent, or an aryloxy group having 6 to 10 carbon atoms which may have a substituent, and when j is 0, Ar ³ is If j is 1 or more, any of Ar ^3, Ar ⁴ are the .Y ¹ having at least one acid group, a hydroxyl group, a thiol group, or an amino group, the two Y ¹ are each It is the same, or different may .Q ¹ also be a direct bond, and the following groups It represents et chosen group, when j is 2, two Q ¹ is also the same as each other or may be different.)

[4] The copolymer according to any one of [1] to [3], wherein (C) includes a compound represented by the following formula (3):

(In the formula, m represents 0, 1 or 2, Ar ⁵ and Ar ⁶ each independently represent a divalent aromatic group, and when m is 2, two Ar ⁶ are the same as or different from each other. Here, these divalent aromatic groups are an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, and a substituent. also aryl group having 6 to 10 carbon atoms having a may also have a substituent aryloxy group having 6 to 10 carbon atoms, a fluoro group, optionally .X ² be substituted by nitro group or a benzoyl group represents a leaving group, where the leaving group is fluoro, chloro, selected from a nitro group or a trifluoromethanesulfonyloxy group, also the two X ² are identical to each other, may .Z ² be different from the following It is selected from the group, when m is 2, two Z ² Be the same each other, it may be different.)

[5] The copolymer according to any one of [1] to [4], wherein (D) includes a compound represented by the following formula (4):

(In the formula, n represents 0, 1 or 2, Ar ⁷ and Ar ⁸ each independently represent a divalent aromatic group, and when n is 2, two Ar ⁸ are the same or different from each other. Here, these divalent aromatic groups are an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, and a substituent. It may be substituted with an aryl group having 6 to 10 carbon atoms, which may have a substituent, or an aryloxy group having 6 to 10 carbon atoms, which may have a substituent, and Y ² is a phenolic hydroxyl group, a thiol group or an amino group. And two Y ^{2 s} may be the same or different from each other, Q ² is a direct bond or a group selected from the following group, and when n is 2, two Q ^{2 s} may be the same as each other , May be different.)
[6] The copolymer according to any one of [1] to [5], wherein the acid group is a strong acid group or a super strong acid group. [7] The ion exchange capacity is 0.1 meq / g to 4. In the copolymer [8] copolymer according to any one of [1] to [6], which is 0 meq / g, the structural unit having an acid group introduced therein and the acid group being substantially introduced. The weight composition ratio of the non-structural units is 3:97 to 70:30, represented by [structural unit into which acid groups are introduced]: [structural unit into which acid groups are not substantially introduced]. Any one of [1] to [7]

The present invention also provides:
[9] A polymer electrolyte comprising any one of the copolymers [1] to [8] is provided. Furthermore, the following [10] to [11] are provided from the polymer electrolyte described in [9].
[10] A polymer comprising the polymer electrolyte of [9] [9], wherein the polymer electrolyte of [9] [9] is impregnated into a porous substrate, and composited A catalyst composition comprising a polymer electrolyte of an electrolyte composite membrane [12] [9] and a catalyst substance

Furthermore, the present invention provides the following polymer electrolyte fuel cells [13] to [15] using the above [10] to [12] as members for polymer electrolyte fuel cells.
[13] A polymer electrolyte membrane characterized by using the polymer electrolyte membrane according to [10], and a polymer electrolyte composite membrane according to [14] [11] A polymer electrolyte fuel cell comprising a catalyst layer obtained from the catalyst composition according to the molecular electrolyte fuel cell [15] [12]

The copolymer of the present invention exhibits excellent performance in various properties such as water resistance, film-forming property, and proton conductivity as a polymer electrolyte, particularly a proton conductive membrane of a fuel cell. Excellent water resistance.
In addition, when used as a proton conductive membrane of a fuel cell, the copolymer of the present invention is industrially advantageous as a polymer electrolyte because it exhibits high power generation characteristics.

Hereinafter, preferred embodiments of the present invention will be described.
The copolymer of the present invention comprises two specific types of monomers having acid groups as the essential monomers (the above (A) and (C)) and two specific types of monomers substantially free of acid groups. (B) and (D) above are obtained by mixing and polycondensing.

The (A) preferably includes the compound represented by the formula (1). Here, when k is 0, the acid group is present in Ar ^1, and when k is 1 or more, the acid group is present in at least one of Ar ¹ and Ar ² . Ar ¹ and Ar ² represent a divalent aromatic group, and examples of the divalent aromatic group include hydrocarbon aromatic groups such as a phenylene group, a naphthylene group, a biphenylylene group, and a fluorenediyl group, pyridinediyl, Examples thereof include heterocyclic groups such as quinoxalinediyl and thiophenediyl. Among them, a divalent hydrocarbon-based aromatic group is preferable, and a phenylene group and a naphthylene group are particularly preferable. Further, when k is 1, Ar ¹ and Ar ² , and when k is 2, Ar ¹ and two Ar ² may be the same or different.

Here, the said bivalent aromatic group has a C1-C10 alkyl group which may have a substituent, a C1-C10 alkoxy group which may have a substituent, and a substituent. There may be an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms that may have a substituent, a nitro group, a benzoyl group, etc., and a carbon that may have a substituent. Examples of the alkyl group having 1 to 10 include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, allyl group, n-butyl group, sec-butyl group, tert-butyl group, isobutyl group, and n-pentyl. Group, 2,2-dimethylpropyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, 2-methylpentyl group, 2-ethylhexyl group and the like. A substituent selected from a halogen atom of chlorine atom, bromine atom or iodine atom, hydroxyl group, amino group, methoxy group, ethoxy group, isopropyloxy group, phenyl group, naphthyl group, phenoxy group and naphthyloxy group. May be.

Examples of the alkoxy group having 1 to 10 carbon atoms that may have a substituent include a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, an n-butyloxy group, a sec-butyloxy group, a tert-butyloxy group, Isobutyloxy group, n-pentyloxy group, 2,2-dimethylpropyloxy group, cyclopentyloxy group, n-hexyloxy group, cyclohexyloxy group, 2-methylpentyloxy group, 2-ethylhexyloxy group, and the like. These groups may be substituted with a substituent selected from a halogen atom, hydroxyl group, amino group, methoxy group, ethoxy group, isopropyloxy group, phenyl group, naphthyl group, phenoxy group and naphthyloxy group.

Examples of the aryl group having 6 to 10 carbon atoms which may have a substituent include a phenyl group and a naphthyl group. These groups include a halogen atom, a hydroxyl group, an amino group, a methoxy group, an ethoxy group, and isopropyl. A substituent selected from an oxy group, a phenyl group, a naphthyl group, a phenoxy group, and a naphthyloxy group may be substituted.

Examples of the aryloxy group having 6 to 10 carbon atoms that may have a substituent include a phenoxy group and a naphthyloxy group. These groups include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. , A hydroxyl group, an amino group, a methoxy group, an ethoxy group, an isopropyloxy group, a phenyl group, a naphthyl group, a phenoxy group, and a naphthyloxy group may be substituted.

Ar ¹ and Ar ² in the formula (1) represent a divalent aromatic group that may have the above-described substituents, and among them, Ar ¹ and Ar ² are unsubstituted phenylene groups or naphthylenes. Group is preferred, 1,3-phenylene group, 1,4-phenylene group, 1,3-naphthalenediyl group, 1,4-naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalenediyl group, 3,3′-biphenylylene group, 3,4′-biphenylylene group, and 4,4′-biphenylylene group are preferable.

In the formula (1), k represents 0, 1 or 2, and Z ¹ represents CO (carbonyl group), SO ₂ (sulfonyl group) or COCO (dicarbonyl group). When k is 2, two Z ^{1 s} may be the same or different from each other, but it is particularly preferable that Z ^{1 be} the same.

In the present invention, as described above, at least one of Ar ¹ and Ar ² out of Ar ¹ and Ar ² has an acid group, but k is 1 or more. , Ar ¹ and Ar ² are preferably all having an acid group.

Here, examples of the acid group include weak acid groups such as carboxyl group (—COOH), phosphonic acid group (—PO ₃ H ₂ ), and phosphoric acid group (—OPO ₃ H ₂ ), and sulfonic acid groups (—SO _3). H), a strong acid group such as a sulfonylimide group (—SO ₂ NHSO ₂ —R, wherein R represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms), a perfluoroalkylenesulfonic acid group, Super strong acid groups such as a perfluorophenylene sulfonic acid group and a perfluoroalkylene sulfonylimide group may be mentioned. Among them, a strong acid group and a super strong acid group having an acid dissociation constant represented by a pKa value of 2 or less are preferable. For example, a sulfonic acid group, a perfluoroalkylenesulfonic acid group, and a perfluorophenylenesulfonic acid group are preferable. Further, when these acid groups are protonic acids, salts may be formed with alkali metal ions, alkaline earth metal ions, ammonium ions, etc., and the acid groups forming these salts are the present invention. After the copolymer is formed, it can be easily returned to the free acid form by ion exchange by acid treatment.

（式中、ｒ、ｓはそれぞれ独立に０又は１を表すが、ｒ＋ｓは１又は２である。Ｍは水素原子、カリウム原子、ナトリウム原子又はリチウム原子を表し、Ｍが複数ある場合、それらは同一でも異なっていてもよい。） Preferable examples of the compound represented by the formula (1) include the following (1) -1 to (1) -4.

(In the formula, r and s each independently represent 0 or 1, but r + s is 1 or 2. M represents a hydrogen atom, a potassium atom, a sodium atom, or a lithium atom. They may be the same or different.)

The (B) preferably includes a compound represented by the formula (2).
Here, the acid group is characterized by having Ar ³ when j is 0, and at least one of Ar ³ and Ar ⁴ when j is 1 or more. Ar ³ and Ar ⁴ represent a divalent aromatic group, and examples of the divalent aromatic group include the same groups as Ar ¹ and Ar ² described above, and when j is 2, Ar ³ and the two Ar ⁴ may be the same as or different from each other. In the nucleophilic group represented by Y ¹ , the phenolic hydroxyl group is a group that functions as a nucleophilic group by converting it to a phenolate group with an appropriate base in the condensation reaction process, and further during the copolymerization of the present invention. It is a group existing as an ether bond and is not regarded as an acid group.
These divalent aromatic groups have a C1-C10 alkyl group which may have a substituent, a C1-C10 alkoxy group which may have a substituent, and a carbon which may have a substituent. The alkyl group, the alkoxy group, the aryl group or the aryloxy group may be substituted with an aryl group having 6 to 10 carbon atoms or an aryloxy group having 6 to 10 carbon atoms which may have a substituent. Examples are the same as described above.

Ar ³ and Ar ⁴ in the formula (2) represent a divalent aromatic group that may have a substituent as described above. Among them, Ar ³ and Ar ⁴ are an unsubstituted phenylene group or biphenylylene group. Or a naphthylene group is preferable, 1,3-phenylene group, 1,4-phenylene group, 1,3-naphthalenediyl group, 1,4-naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group Group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalenediyl group, 3,3′-biphenylylene group, 3,4′-biphenylylene group, or 4,4′-biphenylylene group Is preferred.

In formula (2), j represents 0, 1 or 2, Q ¹ represents a direct bond or a group selected from the following group. When j is 2, two Q ¹ may be the same or different from each other, but the two Q ¹ are preferably the same.

（式中、ｒ、ｓ及びＭは前記と同義である。） Preferable examples of the compound represented by the formula (2) include the following (2) -1 to (2) -12.

(In the formula, r, s and M have the same meanings as described above.)

Next, a monomer substantially having no acid group will be described. Here, “substantially free of acid groups” means that substantially no acid groups exist in the process of forming the copolymer of the present invention, such as the above-mentioned phenolic hydroxyl groups, even if they exist. Suppose not.

The (C) preferably includes a compound represented by the formula (3).
In formula (3), Ar ⁵ and Ar ⁶ are divalent aromatic groups such as phenylene group, naphthylene group, biphenylylene group, fluorenediyl group and other hydrocarbon-based aromatic groups, pyridinediyl group, and quinoxalinediyl group. And a heterocyclic group such as a thiophenediyl group, preferably a divalent hydrocarbon aromatic group. When m is 1, Ar ⁵ and Ar ⁶ , and when m is 2, Ar ⁵ and the two Ar ⁶ may be the same or different.
These divalent aromatic groups have a C1-C10 alkyl group which may have a substituent, a C1-C10 alkoxy group which may have a substituent, and a carbon which may have a substituent. It may be substituted with an aryloxy group having 6 to 10 carbon atoms, a nitro group or a benzoyl group, which may have an aryl group or a substituent of several 6 to 10, and the alkyl group, the alkoxy group, the aryl group or Specific examples of the aryloxy group include the same ones as described above.
Among them, as Ar ⁵ and Ar ⁶ , an unsubstituted phenylene group or naphthylene group is preferable, and 1,3-phenylene group, 1,4-phenylene group, 1,3-naphthalenediyl group, 1,4-naphthalenediyl group are preferable. 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalenediyl group, 3,3′-biphenylylene group, 3 4,4′-biphenylylene group or 4,4′-biphenylylene group is preferred.

In the formula (3), m represents 0, 1 or 2, and Z ² represents CO, SO ₂ or COCO. When m is 2, two Z ² may be the same or different from each other, but are preferably the same.

Preferable examples of the compound represented by the formula (3) include the following (3) -1 to (3) -9.

The (D) preferably includes a compound represented by the formula (4).
Ar ⁷ and Ar ⁸ in the formula (4) represent a divalent aromatic group, and examples equivalent to the above Ar ⁵ and Ar ⁶ can be given. These divalent aromatic groups have a substituent. It may have an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 10 carbon atoms which may have a substituent or a substituent. The aryloxy group having 6 to 10 carbon atoms may be substituted, and specific examples of the alkyl group, the alkoxy group, the aryl group or the aryloxy group include the same ones as described above.
Among them, as Ar ⁷ and Ar ⁸ , an unsubstituted phenylene group, biphenylylene group or naphthylene group is preferable, and 1,3-phenylene group, 1,4-phenylene group, 1,3-naphthalenediyl group, 1,4-naphthalene group is preferable. Diyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalenediyl group, 3,3′-biphenylylene group 3,4′-biphenylylene group or 4,4′-biphenylylene group is preferred.

In formula (4), n represents 0, 1 or 2, and Q ² represents a direct bond or a group selected from the following group. When n is 2, two Q ² may be the same or different from each other, but are preferably the same.

Preferable examples of the compound represented by the formula (4) include the following (4) -1 to (4) -26.

The preferable copolymer of this invention is obtained by using the compound shown by said Formula (1)-Formula (4) as a monomer, mixing these, and condensing. Examples of the production method include a method of condensing nucleophilic substitution of the compounds represented by the formulas (1) to (4) under the action of a base.
Specifically, the compound represented by the formulas (1) to (4) and the basic compound are previously added to the reaction solvent and mixed. The order of mixing is not particularly limited, but after the compound represented by the formula (2), the compound represented by the formula (4), the basic compound and the solvent are first added, the formula (1) and (3) is added and mixed, or the compounds represented by the formulas (1) to (4) and the solvent are mixed, and then the basic compound is added and mixed, or the formulas (1) to (4) are mixed. (4) A mixing means in which a basic compound and a solvent are added and mixed is preferable. The reaction temperature in the condensation is preferably 20 to 300 ° C, more preferably 50 to 250 ° C, and the reaction time is preferably 0.5 to 500 hours, more preferably 1 to 100 hours. Further, the pressure during the reaction may be increased or decreased, but preferably normal pressure (about 1 atm) is preferable because of the simplicity of equipment. Reaction solvents include alcohol solvents such as methanol, ethanol, isopropanol, butanol, diethyl ether, dibutyl ether, diphenyl ether, tetrahydrofuran, dioxane, dioxolane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol Ether solvents such as monoethyl ether, ketone solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, benzophenone, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, etc. N, N-dimethylacetamide (hereinafter sometimes abbreviated as DMAc) Amide solvents such as N-methylacetamide, N, N-dimethylformamide (hereinafter sometimes abbreviated as DMF), N-methylformamide, formamide, N-methylpyrrolidone (hereinafter also abbreviated as NMP), formic acid Esters such as methyl, methyl acetate and γ-butyrolactone, nitriles such as acetonitrile and butyronitrile, sulfoxydimethyl sulfoxide (hereinafter sometimes abbreviated as DMSO), diphenylsulfone, sulfolane and the like can be used. A solvent can be used individually or in combination of 2 or more types. In addition, the usage-amount of the reaction solvent is 1.0-200.0 weight times with respect to the total weight of the monomer to apply, Preferably it uses 2.0-100.0 weight times. In addition, it is preferable to remove water by-produced at the initial stage of the condensation reaction or during the condensation reaction. As a means for removing this water, it is possible to use a means for removing water as an azeotrope by coexisting toluene or xylene in the reaction system, or a means for dehydrating by coexisting a water absorbing agent such as molecular sieve in the reaction system. it can. As the basic compound, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate or potassium hydrogen carbonate can be used, and two or more basic compounds can be mixed and used. Among them, potassium carbonate, sodium carbonate or sodium hydroxide is preferable. In addition, as the usage-amount of this basic compound, it is 0.90-10.00 molar equivalent times with respect to the total number of molar equivalents of a nucleophilic group in the monomer used for condensation reaction, Preferably it is 1.00-3. What is necessary is just to use 00 molar equivalent times.

In another embodiment of the preferred method for producing a copolymer of the present invention, the compound represented by the formula (2) and the compound represented by the formula (4) are reacted with a basic compound in advance, Examples thereof include a method in which a compound represented by 1) and a compound represented by formula (3) are added, mixed and condensed. That is, the compound represented by the formula (2), the compound represented by the formula (4) and the basic compound are mixed in a reaction solvent, followed by heat treatment as necessary, and the compound represented by the formula (2). A basic compound is allowed to act on the compound represented by formula (4), and then the compound represented by formula (1) and the compound represented by formula (3) are added to perform a condensation reaction. At that time, the reaction solvent to be used and its use amount, the basic compound to be used and its use amount are the same as described above, and the reaction temperature and reaction time for the condensation reaction are also in the same range as described above. The removal of by-product water can be carried out in the same manner as described above, and the compound represented by formula (2), the compound represented by formula (4) and a basic compound are mixed in a reaction solvent. In the process, toluene and xylene are allowed to coexist in the reaction system to sufficiently remove water as an azeotrope, and then a condensation reaction is performed by adding the compound represented by the formula (1) and the compound represented by the formula (3). But you can.

Thus, the copolymer of the present invention is obtained. In the copolymer, the weight composition ratio of the structural unit in which the acid group is introduced and the structural unit in which the acid group is not substantially introduced is not particularly limited. Structural unit]: [Structural unit in which an acid group is not substantially introduced] is 3:97 to 70:30, preferably 5:95 to 45:55, and 10:90 to 40: 60 is more preferable, and 20:80 to 35:65 is particularly preferable. A copolymer having an acid group-introduced structural unit in the above range is a polymer electrolyte membrane having both high proton conductivity and water resistance when applied to a polymer electrolyte membrane of a fuel cell membrane.
In addition, the weight composition ratio of the structural unit in which the acid group is introduced and the structural unit in which the acid group is not substantially introduced can be controlled by the amount of the monomer used. For example, in the formula (1) A total molar amount of the monomer having an acid group including the compound represented by formula (2) and the compound represented by formula (2), and an acid group comprising the compound represented by formula (3) and the compound represented by formula (4) substantially. It can be arbitrarily controlled by changing the charge (mixing) molar ratio at the initial stage of the reaction with the total molar amount of the monomers not present.

Further, when the introduction amount of the acid groups as the whole copolymer is expressed by the equivalent number of acid groups per 1 g of the copolymer, that is, the ion exchange capacity, 0.1 meq / g to 4.0 meq / g is preferable. 0.5 meq / g to 2.5 meq / g is more preferable, and 1.3 meq / g to 2.3 meq / g is particularly preferable. The reason why the ion exchange capacity is suitable in such a range is the same reason as the content weight ratio of the structural unit into which the acid group is introduced in the copolymer, and the ion exchange capacity is the same as described above. Thus, it can be arbitrarily controlled by changing the charge (mixing) molar ratio of each monomer in the initial reaction.

The average molecular weight of the copolymer of the present invention is preferably 5000 to 1000000, particularly preferably 15000 to 200000, expressed in terms of polystyrene-reduced number average molecular weight.
Such average molecular weight can be controlled by the ratio of the total number of molar equivalents of the nucleophilic group of the monomer to be applied and the total number of molar equivalents of the leaving group, the reaction time, and the like.

Next, the case where the copolymer of the present invention is used as a diaphragm (polymer electrolyte membrane) of an electrochemical device such as a fuel cell will be described.
In this case, the copolymer of the present invention is usually used in the form of a film. Although there is no restriction | limiting in particular in the method to convert into a film | membrane, For example, the method (solution cast method) which forms into a film from a solution state is used preferably.
Specifically, the film is formed by dissolving the copolymer in an appropriate solvent, casting the solution on a glass plate, and removing the solvent. The solvent used for film formation is not particularly limited as long as it can dissolve the copolymer and can be removed thereafter. Water, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl -2-pyrrolidone, dimethyl sulfoxide) and other aprotic polar solvents, or chlorine-containing solvents such as dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene, alcohols such as methanol, ethanol and propanol, ethylene glycol monomethyl Alkylene glycol monoalkyl ethers such as ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether are preferably used. These can be used singly, but two or more solvents can be mixed and used as necessary. Among them, DMSO, DMF, DMAc, and NMP are preferable because of high polymer solubility.

Although there is no restriction | limiting in particular in the thickness of a film | membrane, 10-300 micrometers is preferable and 20-100 micrometers is especially preferable. When the film is thinner than 10 μm, the practical strength may not be sufficient, and when the film is thicker than 300 μm, the film resistance tends to increase and the characteristics of the electrochemical device tend to deteriorate. The thickness of the film can be controlled by the concentration of the solution and the coating thickness on the substrate.

In addition, for the purpose of improving various physical properties of the polymer electrolyte membrane, plasticizers, stabilizers, release agents and the like used for ordinary polymers can be added to the copolymer of the present invention. Also, other polymers can be combined with the copolymer of the present invention by a method such as co-casting in the same solvent.
In fuel cell applications, it is also known to add inorganic or organic fine particles as a water retention agent in order to facilitate water management. Any of these known methods can be used as long as they are not contrary to the object of the present invention. In addition, for the purpose of improving the mechanical strength of a polymer electrolyte membrane comprising a polymer electrolyte containing the copolymer of the present invention, the polymer constituting the polymer electrolyte membrane is irradiated with an electron beam or radiation. The electrolyte can also be crosslinked.

In order to further improve the strength, flexibility, and durability of the polymer electrolyte membrane, the polymer of the present invention may be impregnated into a porous base material to form a polymer electrolyte composite membrane. Is possible. A known method can be used as the compounding method. The porous substrate is not particularly limited as long as it satisfies the above-mentioned purpose of use, and examples thereof include porous membranes, woven fabrics, non-woven fabrics, and fibrils, and they can be used regardless of their shapes and materials.

When the polymer electrolyte composite membrane using the copolymer of the present invention is used as a diaphragm of a fuel cell, the porous substrate has a thickness of 1 to 100 μm, preferably 3 to 30 μm, more preferably 5 to 20 μm. Yes, the pore diameter is 0.01 to 100 μm, preferably 0.02 to 10 μm, and the porosity is 20 to 98%, preferably 40 to 95%.
If the thickness of the porous substrate is too thin, the effect of reinforcing the strength after compounding or the reinforcing effect of imparting flexibility and durability is insufficient, and gas leakage (cross leak) is likely to occur. On the other hand, if the film thickness is too thick, the electric resistance becomes high, and the obtained composite film becomes insufficient as a diaphragm of the polymer electrolyte fuel cell. When the pore diameter is too small, it is difficult to fill the copolymer of the present invention, and when it is too large, the reinforcing effect on the polymer solid electrolyte is weakened. If the porosity is too small, the resistance of the composite film is increased, and if it is too large, the strength of the porous substrate itself is generally weakened and the reinforcing effect is reduced.
From the viewpoint of heat resistance and the effect of reinforcing physical strength, the porous substrate is preferably a substrate made of an aliphatic polymer, an aromatic polymer, or a fluorine-containing polymer.

Next, the fuel cell of the present invention will be described. Examples of a fuel cell using a polymer electrolyte membrane include a solid polymer fuel cell using hydrogen gas as a fuel and a direct methanol solid polymer fuel cell directly supplying methanol as a fuel. The polymer can be suitably used for either of them.
The fuel cell obtained by the present invention uses the copolymer of the present invention as a polymer electrolyte membrane and / or a polymer electrolyte composite membrane, or uses the polymer electrolyte of the present invention as a polymer electrolyte in a catalyst layer. Can be mentioned.

A fuel cell using the copolymer of the present invention as a polymer electrolyte membrane or a polymer electrolyte composite membrane is obtained by joining a catalyst and a gas diffusion layer on both sides of the polymer electrolyte membrane or the polymer electrolyte composite membrane. Can be manufactured. A known material can be used for the gas diffusion layer, but a porous carbon woven fabric, carbon non-woven fabric or carbon paper is preferable in order to efficiently transport the raw material gas to the catalyst.

Here, the catalyst is not particularly limited as long as it can activate the oxidation-reduction reaction with hydrogen or oxygen, and a known catalyst can be used, but platinum fine particles are preferably used. The platinum fine particles are often preferably those supported on particulate or fibrous carbon such as activated carbon or graphite. Also, platinum supported on carbon is mixed with an alcohol solution of perfluoroalkylsulfonic acid resin as a polymer electrolyte to make a paste, which is then applied to a gas diffusion layer, polymer electrolyte membrane or polymer electrolyte composite membrane -A catalyst layer is obtained by drying. As a specific method, for example, J. Org. Electrochem. Soc. : Known methods such as those described in Electrochemical Science and Technology, 1988, 135 (9), 2209 can be used.

Examples of the fuel cell using the copolymer of the present invention as a polymer electrolyte in the catalyst layer include those using the copolymer of the present invention instead of the perfluoroalkylsulfonic acid resin constituting the catalyst layer. be able to. When the catalyst layer using the copolymer of the present invention is used, the polymer electrolyte membrane is not limited to the membrane using the copolymer of the present invention, and a known polymer electrolyte membrane can be used.

When the catalyst layer is obtained using the copolymer of the present invention, the solvent used for preparing the catalyst paste is arbitrary and not particularly limited, but components other than the solvent constituting the catalyst paste are dissolved, It is desired to uniformly disperse at the molecular level, or to form aggregates at the nanometer to micrometer level and disperse the aggregates. The solvent may be a single solvent or a mixture of a plurality of solvents, and the same solvents as those mentioned above can be used when the copolymer is formed into a film.

Other components constituting the catalyst paste are optional and are not particularly limited. For the purpose of increasing the water repellency of the catalyst layer, a water repellent material such as PTFE is used, and for the purpose of increasing the gas diffusibility of the catalyst layer, carbonic acid is added. A pore former such as calcium may contain a stabilizer such as a polymer having a metal oxide or a phosphonic acid group for the purpose of further improving durability.

The catalyst paste is obtained by mixing the polymer electrolyte, the catalyst material and / or a conductive material carrying the catalyst material on the surface, a solvent, and other components by a known method. Examples of the mixing method include an ultrasonic dispersing device, a homogenizer, a ball mill, a planetary ball mill, and a sand mill.

The method for directly applying the catalyst paste is not particularly limited, and existing methods such as a die coater, screen printing, spray method, and ink jet method can be used. However, the spray method is industrially easy to operate. Therefore, it is preferable.

As a method for spraying the catalyst paste, for example, an apparatus and a method described in JP-A-2004-89976 can be specifically exemplified, and these can be used. That is, a polymer electrolyte membrane is placed on a stage, and catalyst ink is directly applied to the polymer electrolyte membrane. In the spray method, catalyst ink scatters in the form of particles from the discharge port and adheres to the polymer electrolyte membrane. The stage is desirably heated in order to remove the solvent immediately after coating, and the temperature is preferably 50 ° C to 150 ° C. A temperature range within the above range is preferable because the solvent of the catalyst ink is easily removed and the polymer electrolyte membrane is less likely to be thermally damaged. Thus, following application by the spray method, the solvent is removed by heating the stage, and the catalyst layer is manufactured on the polymer electrolyte membrane. In order to make the removal of the solvent more reliable, the membrane on which the catalyst layer is produced may be dried in a heated oven or the like, or may be vacuum dried as necessary. In order to remove the solvent more quickly, a suitable solvent constituting the catalyst paste is a solvent having a boiling point of 150 ° C. or lower, an alcohol solvent such as water, methanol, ethanol, or an ether such as diethyl ether or tetrahydrofuran. A system solvent or a mixed solvent thereof may be used, and the copolymer of the present invention is also excellent in that it is easily soluble in these solvents. The catalyst paste may be sprayed a plurality of times, and a layer by each spray may be applied over the polymer electrolyte membrane to form a multilayer coating.

Examples The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Molecular weight measurement:
The number average molecular weight (Mn) in terms of polystyrene was measured by gel permeation chromatography (GPC) under the following conditions.
GPC measuring device HLC-8220 GPC manufactured by TOSOH
Column TSKgel GHM _HR- M manufactured by Shodex
Column temperature 40 ° C
Mobile phase solvent DMAc (LiBr added to 10 mmol / dm ³ )
Solvent flow rate 0.5mL / min
Measurement of proton conductivity:
The measurement was carried out by the alternating current method under conditions of a temperature of 80 ° C. and a relative humidity of 90%.
Measurement of ion exchange capacity:
Determined by titration method.
Measurement of water absorption:
The dried polymer electrolyte membrane was weighed and immersed in deionized water at 100 ° C. for 2 hours, and then the water absorption was calculated from the amount of increase in membrane weight, and the ratio to the dry membrane was determined.

前記の（A-a）、（A-b）、（A-c）及び（A-d）の構造単位の合計に対する、仕込量から計算される各構造単位のモル比
（A-a）：（A-b）：（A-c）：（A-d）＝ ２．００：２．２０：１．２０：１．００
前記構造単位のモル比から計算されるイオン交換容量 ２．３０ ｍｅｑ／ｇ
Ｍｎ ８．１０×１０⁴
イオン交換容量の実測値 ２．１０ ｍｅｑ／ｇ
製膜：ＮＭＰ溶液キャスト法 膜厚 ３３μｍ
プロトン伝導度 １．５６×１０^-1 Ｓ／ｃｍ
吸水率 １６９％ Example 1
Production of copolymer A The polymerization was carried out using a 200 ml separable flask fitted with a Dean-Stark tube. A flask is charged with 3.50 g (15.33 mmol) of potassium hydroquinonesulfonate, 6.29 g (33.76 mmol) of 4,4′-dihydroxybiphenyl, 7.36 g (53.24 mmol) of potassium carbonate, 121 ml of dimethyl sulfoxide and 70 ml of toluene. It is. Thereafter, azeotropic dehydration was carried out in an argon atmosphere at a bath temperature of 150 ° C. (internal temperature 130 ± 5 ° C.) for 1.5 hours. After 1.5 hours, toluene was removed out of the system and allowed to cool to room temperature. Subsequently, 9.03 g (18.40 mmol) of 3,3′-sulfonylbis (6-fluorobenzenesulfonate potassium), 7.80 g (30.69 mmol) of 4,4′-difluorodiphenylsulfone were added, and The reaction was carried out at an internal temperature of 150 ° C. for 11 hours. The reaction was followed by GPC measurement. After completion of the reaction, the reaction solution was allowed to cool to 80 ° C. and added dropwise to 3 L of 2M aqueous hydrochloric acid. The precipitated white polymer was filtered, washed with water until the pH of the washing filtrate was about 7, and then treated with 80 ° C. water for 2 hours twice. After drying in an oven (80 ° C.), 20.86 g (yield 92%) of the copolymer A shown below was obtained. Thereafter, the dried copolymer A was dissolved in N-methylpyrrolidone and then filtered to prepare a solution having a concentration of the copolymer A of 18% by weight. The solution was then cast on a glass substrate to remove N-methylpyrrolidone in a fully evacuated oven at 80 ° C. for about 5 hours. Thereafter, the step of treating with 2N hydrochloric acid for 1 hour was repeated twice, and further washed with running water (deionized water) for 8 hours to obtain a polymer electrolyte membrane. The film thickness was 33 μm.

Copolymer A
Copolymer A is a polymer having the structural units shown below.

The molar ratio (Aa) :( Ab) :( Ac) :( Ad of each structural unit calculated from the charged amount with respect to the total of the structural units (Aa), (Ab), (Ac) and (Ad). ) = 2.00: 2.20: 1.20: 1.00
Ion exchange capacity calculated from the molar ratio of the structural units 2.30 meq / g
Mn 8.10 × 10 ⁴
Measured value of ion exchange capacity 2.10 meq / g
Film formation: NMP solution casting method Film thickness 33μm
Proton conductivity 1.56 × 10 ⁻¹ S / cm
Water absorption 169%

前記の（B-a）、（B-b）、（B-c）及び（B-d）の構造単位の合計に対する、仕込量から計算される各構造単位のモル比
（B-a）：（B-b）：（B-c）：（B-d）＝ ２．５６：２．７６：１．２０：１．００
前記構造単位のモル比から計算されるイオン交換容量 ２．００ ｍｅｑ／ｇ
Ｍｎ ８．２０×１０⁴
イオン交換容量の実測値 １．８０ ｍｅｑ／ｇ
製膜：ＮＭＰ溶液キャスト法 ２６μｍ
プロトン伝導度 ８．８４×１０^-2 Ｓ／ｃｍ
吸水率 ９４％ Example 2
Production of copolymer B The polymerization was carried out using a 200 ml separable flask fitted with a Dean-Stark tube. In a flask, potassium hydroquinonesulfonate 3.50 g (15.33 mmol), 4,4′-dihydroxybiphenyl 7.87 g (42.25 mmol), potassium carbonate 8.65 g (62.57 mmol), dimethyl sulfoxide 138 ml and toluene 70 ml Was charged. Thereafter, azeotropic dehydration was carried out in an argon atmosphere at a bath temperature of 150 ° C. (internal temperature 130 ± 5 ° C.) for 1.5 hours. After 1.5 hours, toluene was removed out of the system and allowed to cool to room temperature. Thereafter, 9.03 g (18.40 mmol) of 3,3′-sulfonylbis (6-fluorobenzenesulfonate), 9.96 g (39.18 mmol) of 4,4′-difluorodiphenylsulfone were added, and The reaction was performed at an internal temperature of 150 ° C. for 5 hours. The reaction was followed by GPC measurement. After completion of the reaction, the reaction solution was allowed to cool to 80 ° C. and added dropwise to 3 L of 2M aqueous hydrochloric acid. The precipitated white polymer was filtered, washed with water until the pH of the washing filtrate was about 7, and then treated with water at 80 ° C. for 2 hours twice. After drying in an oven (80 ° C.), 23.62 g (yield 91%) of copolymer B shown below was obtained. Using the same solution casting method as in Example 1, a polymer electrolyte membrane made of copolymer B was formed.

Copolymer B
Copolymer B is a polymer having the structural units shown below.

The molar ratio (Ba) :( Bb) :( Bc) :( Bd) of each structural unit calculated from the charged amount with respect to the total of the structural units (Ba), (Bb), (Bc) and (Bd). ) = 2.56: 2.76: 1.20: 1.00
Ion exchange capacity calculated from the molar ratio of the structural units 2.00 meq / g
Mn 8.20 × 10 ⁴
Measured value of ion exchange capacity 1.80 meq / g
Film formation: NMP solution casting method 26 μm
Proton conductivity 8.84 × 10 ^-2 S / cm
94% water absorption

前記の（C-a）、（C-b）及び（C-c）の構造単位の合計に対する、仕込量から計算される各構造単位のモル比
（C-a）：（C-b）：（C-c）＝ １．４５：０．４５：１．００
前記構造単位のモル比から計算されるイオン交換容量 １．７１ ｍｅｑ／ｇ
Ｍｎ ４．０６×１０⁴
イオン交換容量の実測値 １．５６ ｍｅｑ／ｇ
製膜：ＮＭＰ溶液キャスト法 膜厚 ５４μｍ
プロトン伝導度 ４．６０×１０^-2 Ｓ／ｃｍ
吸水率 ３０２％ Comparative Example 1
Production of copolymer C The polymerization was carried out using a 200 ml separable flask fitted with a Dean-Stark tube. In a flask, 6.18 g (27.0 mmol) of potassium hydroquinonesulfonate, 10.00 g (39.33 mmol) of 4,4′-difluorodiphenylsulfone, 2.28 g (12.25 mmol) of 4,4′-dihydroxybiphenyl, carbonic acid, Charged 5.98 g (43.26 mmol) of potassium, 74 ml of dimethyl sulfoxide and 40 ml of toluene. Thereafter, azeotropic dehydration was performed at 150 ° C. (internal temperature 130 ± 5 ° C.) for 3 hours under an argon atmosphere. After 3 hours, toluene was removed from the system, and the reaction was further carried out at an internal temperature of 150 ° C. for 12 hours. The reaction was followed by GPC measurement. After completion of the reaction, the reaction solution was allowed to cool to 80 ° C. and added dropwise to 3 L of 2M aqueous hydrochloric acid. The precipitated white polymer was filtered, washed with water until the pH of the washing filtrate was about 7, and then treated with water at 80 ° C. for 2 hours twice. It dried in oven (80 degreeC) and obtained the copolymer C14.67g (yield 92%) shown below. Using the same solution casting method as in Example 1, a polymer electrolyte membrane made of Copolymer C was formed.

Copolymer C
Copolymer C is a polymer having the structural units shown below.

The molar ratio (Ca) :( Cb) :( Cc) = 1.45: 0. Of the respective structural units calculated from the charged amount with respect to the total of the structural units (Ca), (Cb) and (Cc). 45: 1.00
Ion exchange capacity calculated from the molar ratio of the structural units 1.71 meq / g
Mn 4.06 × 10 ⁴
Measured value of ion exchange capacity 1.56 meq / g
Film production: NMP solution casting method Film thickness 54μm
Proton conductivity 4.60 × 10 ^-2 S / cm
Water absorption 302%

前記の（D-a）、（D-b）及び（D-c）の構造単位の合計に対する、仕込量から計算される各構造単位のモル比
（D-a）：（D-b）：（D-c）＝ １．００：２．００：１．０２
前記構造単位のモル比から計算されるイオン交換容量 ２．０８ ｍｅｑ／ｇ
Ｍｎ ７．７０×１０⁴
イオン交換容量の実測値 １．９７ ｍｅｑ／ｇ
製膜：ＮＭＰ溶液キャスト法 膜厚 ２６μｍ
プロトン伝導度 ０．９７×１０^-1 Ｓ／ｃｍ
吸水率 ４６０％ Comparative Example 2
Production of copolymer D The polymerization was carried out using a 500 ml separable flask fitted with a Dean-Stark tube. In a flask, 12.74 g (50.10 mmol) of 4,4′-difluorodiphenylsulfone, 18.62 g (100.00 mmol) of 4,4′-dihydroxybiphenyl, potassium 3,3′-sulfonylbis (6-fluorobenzenesulfonate) ) 25.08 g (50.00 mmol), 15.20 g (110.00 mmol) of potassium carbonate, 160 ml of N-methyl-2-pyrrolidone and 80 ml of toluene were charged. Thereafter, azeotropic dehydration was performed at an internal temperature of 140 ° C. for 5 hours in an argon atmosphere. After 3 hours, toluene was removed from the system, and the reaction was further performed at an internal temperature of 170 ° C. for 8 hours. The reaction was followed by GPC measurement. After completion of the reaction, the reaction solution was allowed to cool to room temperature and added dropwise to 500 ml of 2M aqueous hydrochloric acid. The precipitated white polymer was washed with water, pulverized into a powder, and washed again with water until pH 7 was reached. Thereafter, the treatment with water at 95 ° C. for 2 hours was performed twice. It dried under reduced pressure in oven (60 degreeC), and obtained the copolymer D45.31g (93% of yield) shown below. A polymer electrolyte membrane made of the copolymer D was formed using the same solution casting method as in Example 1.

Copolymer D
Copolymer D is a polymer having the structural units shown below.

The molar ratio (Da) :( Db) :( Dc) = 1.00: 2. Of each structural unit calculated from the charged amount with respect to the total of the structural units (Da), (Db) and (Dc). 00: 1.02
Ion exchange capacity calculated from the molar ratio of the structural units 2.08 meq / g
Mn 7.70 × 10 ⁴
Measured value of ion exchange capacity 1.97 meq / g
Film formation: NMP solution casting method Film thickness 26μm
Proton conductivity 0.97 × 10 ⁻¹ S / cm
Water absorption 460%

上記（E-a）、（E-b）、（E-c）及び（E-d）の構造単位に対する、仕込量から計算されるモル比
（E-a）：（E-b）：（E-c）：（E-d）＝ １．６７：１．８７：１．２０：１．００
上記モル比から計算されるイオン交換容量 ２．００ ｍｅｑ／ｇ
Ｍｎ ６．２×１０⁴
イオン交換容量の実測値 １．９０ ｍｅｑ／ｇ
製膜：ＮＭＰ溶液キャスト法 ３３μｍ
プロトン伝導度 ０．９５×１０^-1 Ｓ／ｃｍ
吸水率 ８８％ Example 3
Production of copolymer E The polymerization was carried out using a 200 ml separable flask fitted with a Dean-Stark tube. In the flask, 3.00 g (13.14 mmol) of potassium hydroquinonesulfonate, 8.31 g (24.57 mmol) of 4,4′-dihydroxy-3,3′-diphenylbiphenyl, 5.42 g (39.21 mmol) of potassium carbonate, dimethyl 105 ml of sulfoxide and 60 ml of toluene were charged. Thereafter, azeotropic dehydration was performed at 150 ° C. (internal temperature 130 ± 5 ° C.) for 2 hours under an argon atmosphere. After 2 hours, toluene was removed out of the system and allowed to cool to room temperature. Thereafter, 7.17 g (15.77 mmol) of dipotassium 4,4′-difluorobenzophenone-3,3′-disulfonate and 5.57 g (21.90 mmol) of 4,4′-difluorodiphenylsulfone were added, and the internal temperature was further increased. The reaction was performed at 150 ° C. for 25 hours. The reaction was followed by GPC measurement. After completion of the reaction, the reaction solution was allowed to cool to 80 ° C. and added dropwise to 3 L of 2M aqueous hydrochloric acid. The precipitated white polymer was filtered, washed with water until the pH of the washing filtrate was about 7, and then treated with 80 ° C. water for 2 hours twice. It dried in oven (80 degreeC) and obtained the copolymer E18.96g (yield 91%) shown below. Using a solution casting method similar to that of Example 1, a polymer electrolyte membrane made of copolymer E was formed.

Copolymer E
Copolymer E is a polymer having the structural units shown below.

The molar ratio (Ea) :( Eb) :( Ec) :( Ed) = 1.67: 1 calculated from the charged amount with respect to the structural units (Ea), (Eb), (Ec) and (Ed) above. .87: 1.20: 1.00
Ion exchange capacity calculated from the above molar ratio 2.00 meq / g
Mn 6.2 × 10 ⁴
Measured value of ion exchange capacity 1.90 meq / g
Film formation: NMP solution casting method 33 μm
Proton conductivity 0.95 × 10 ^-1 S / cm
Water absorption 88%

前記の（F-a）、（F-b）、（F-c）、（F-d）及び（F-e）の構造単位の合計に対する、仕込量から計算される各構造単位のモル比
（F-a）：（F-b）：（F-c）：（F-d）：（F-e）
＝ ２．４０：１．３０：１．３０：１．２０：１．００
前記構造単位のモル比から計算されるイオン交換容量 １．８０ ｍｅｑ／ｇ
Ｍｎ ３．３×１０⁴
イオン交換容量の実測値 １．６２ ｍｅｑ／ｇ
製膜：ＮＭＰ溶液キャスト法 ６０μｍ
プロトン伝導度 ０．６２×１０^-1 Ｓ／ｃｍ
吸水率 １０４％ Example 4
Copolymer F
The polymerization was performed using a 200 ml separable flask fitted with a Dean-Stark tube. In a flask, 3.00 g (13.14 mmol) of potassium hydroquinonesulfonate, 5.79 g (17.11 mmol) of 4,4′-dihydroxy-3,3′-diphenylbiphenyl, 2,2′-bis (4-hydroxyphenyl) ) 3.91 g (17.11 mmol) of propane, 7.74 g (15.7 mmol) of 3,3′-sulfonylbis (6-fluorobenzenesulfonate potassium), 8.04 g (31 of 4,4′-difluorodiphenylsulfone) 60 mmol), 6.87 g (49.74 mmol) of potassium carbonate, 114 ml of dimethyl sulfoxide and 40 ml of toluene. Thereafter, azeotropic dehydration was performed at 150 ° C. (internal temperature 130 ± 5 ° C.) for 2 hours under an argon atmosphere. After 2 hours, toluene was removed from the system, and the reaction was further performed at an internal temperature of 150 ° C. for 3 hours. The reaction was followed by GPC measurement. After completion of the reaction, the reaction solution was allowed to cool to 80 ° C. and added dropwise to 1 L of 2M aqueous hydrochloric acid. The precipitated polymer was filtered, washed with water until the pH of the washing filtrate was about 7, and then treated twice with water at 80 ° C. for 2 hours. It was dried in an oven (80 ° C.) to obtain 23.31 g (yield 87%) of copolymer F shown below. A polymer electrolyte membrane made of the copolymer F was formed using the same solution casting method as in Example 1.

Copolymer F
The copolymer F is a polymer having the structural units shown below.

The molar ratio (Fa) :( Fb) :( Fc) of each structural unit calculated from the charged amount with respect to the total of the structural units (Fa), (Fb), (Fc), (Fd) and (Fe). ): (Fd): (Fe)
= 2.40: 1.30: 1.30: 1.20: 1.00
Ion exchange capacity calculated from the molar ratio of the structural units 1.80 meq / g
Mn 3.3 × 10 ⁴
Measured value of ion exchange capacity 1.62 meq / g
Film formation: NMP solution casting method 60 μm
Proton conductivity 0.62 × 10 ⁻¹ S / cm
Water absorption 104%

Example 5
[Manufacture of catalyst paste]
A uniform copolymer A solution (concentration of copolymer A; 5% by weight) obtained by mixing 95 g of a mixed solvent of water: ethanol = 1: 9 (weight ratio) and 5 g of copolymer A obtained in Example 1 Was prepared. Separately, 0.64 g of platinum-supported carbon (SA50BK, manufactured by N.E. Chemcat; 50% by weight of platinum) was added to and mixed with 11 mL of ethanol, and 1.05 g of the copolymer A solution prepared earlier was further added. It was. The obtained mixture was subjected to ultrasonic treatment for 1 hour and then stirred with a stirrer for 6 hours to obtain catalyst ink A.

[Manufacture of polymer electrolyte membranes]
With reference to JP-A-2005-139432, a polymer electrolyte membrane comprising a block copolymer type polymer electrolyte represented by the following formula was obtained. Specifically, a first polymer compound having an ion exchange group and a second polymer compound having substantially no ion exchange group are respectively synthesized as shown below and further coupled. Thus, a block copolymer type polymer electrolyte was synthesized.

(Synthesis of the first polymer compound)
In a flask equipped with an azeotropic distillation apparatus, under an argon atmosphere, 283.68 g of dipotassium 4,4′-difluorodiphenylsulfone-3,3′-disulfonate, 120.00 g of potassium 2,5-dihydroxybenzenesulfonate, 1778 g of DMSO, And 279 g of toluene was added, and argon gas was bubbled for 1 hour, stirring these at room temperature.
Thereafter, 76.29 g of potassium carbonate was added to the obtained mixture, and azeotropic dehydration was performed by heating and stirring at 140 ° C. Thereafter, heating was continued while distilling off toluene to obtain a DMSO solution of the first polymer compound. Total heating time was 16 hours. The resulting solution was allowed to cool at room temperature.
This first polymer compound had Mn of 3.0 × 10 ⁴ .

(Synthesis of second polymer compound)
To a flask equipped with an azeotropic distillation apparatus, 247.55 g of 4,4′-difluorodiphenylsulfone, 164.44 g of 2,6-dihydroxynaphthalene, 902 g of DMSO, 902 g of NMP, and 310 g of toluene were added in an argon atmosphere at room temperature. While stirring, argon gas was bubbled for 1 hour.
Thereafter, 156.09 g of potassium carbonate was added to the obtained mixture, and azeotropic dehydration under reduced pressure was performed while heating and stirring at 100 ° C. After 17 hours, toluene was distilled off, and heating was further continued at 100 ° C. Total heating time was 19 hours. The resulting solution was allowed to cool at room temperature to obtain an NMP / DMSO mixed solution of the second polymer compound. The Mn of this second polymer compound was 2.7 × 10 ⁴ .

なお、ｎ１およびｍ１は、ブロック共重合体型高分子電解質の各ブロックの平均重合度を表す。
Ｍｎ ７．９×１０⁴
イオン交換容量の実測値 １．９４ ｍｅｑ／ｇ
製膜：ＮＭＰ溶液キャスト法 ２７μｍ
プロトン伝導度 ２．３７×１０^-1 Ｓ／ｃｍ
吸水率 １１５％
仕込から計算された ｎ１＝３６．２であり， ｍ１＝１０．５であった。 (Synthesis of block copolymer type polymer electrolyte)
While stirring the obtained NMP / DMSO mixed solution of the second polymer compound, the whole amount of the DMSO solution of the first polymer compound, 610 g of DMSO and 1790 g of NMP were added thereto, and blocked at 150 ° C. for 39 hours. A copolymerization reaction was performed.
The obtained reaction solution was dropped into a large amount of 2N hydrochloric acid and immersed for 1 hour. Thereafter, the produced precipitate was filtered off and then immersed again in 2N hydrochloric acid for 1 hour. The obtained precipitate was filtered and washed with water, and then immersed in a large amount of hot water at 95 ° C. for 1 hour. After filtering the solid, it was again immersed in a large amount of hot water at 95 ° C. for 1 hour. The solid was filtered off and dried at 80 ° C. overnight to obtain a block copolymer type polymer electrolyte.
Using the same solution casting method as in Example 1, a polymer electrolyte membrane made of a block copolymer type polymer electrolyte was formed.
[Obtained block copolymer type polymer electrolyte]

In addition, n1 and m1 represent the average degree of polymerization of each block of the block copolymer type polymer electrolyte.
Mn 7.9 × 10 ⁴
Measured value of ion exchange capacity 1.94 meq / g
Film formation: NMP solution casting method 27 μm
Proton conductivity 2.37 × 10 ⁻¹ S / cm
115% water absorption
Calculated from the feed, n1 = 36.2 and m1 = 10.5.

[MEA]
The polymer electrolyte membrane comprising the block copolymer type polymer electrolyte thus obtained was cut into a square and set on a heating stage, and the catalyst ink A was sprayed onto a 5.2 cm square area at the center of the membrane main surface. Was applied. The distance from the discharge port to the film was set to 5 cm, and the stage temperature was set to 76 ° C. After coating, the solution was left on the stage for 3 minutes to remove the solvent and form a catalyst layer. The polymer electrolyte membrane provided with the catalyst layer on one side thus obtained was turned over and set on the heating stage, and the catalyst layer from the catalyst ink A was also applied to the other side in the same manner as the catalyst layer. This formed a membrane-catalyst layer assembly. The platinum amount of the catalyst layer determined from the weight composition of the catalyst layer and the weight of the applied catalyst layer was 0.6 mg / cm ² per side.

[Assembly of fuel cell evaluation cell]
A fuel cell was manufactured using a commercially available JARI standard cell. That is, a carbon separator with a gas cloth groove and a carbon separator cut into gas passages is disposed on both catalyst layers of the membrane-catalyst layer assembly obtained as described above, and further on the outside thereof. A fuel cell having an effective membrane area of 25 cm ² was assembled by sequentially arranging a current collector and an end plate and fastening them with bolts.

[Fuel cell evaluation]
While keeping the obtained fuel cells at 80 ° C., humidified hydrogen was supplied to the anode and humidified air was supplied to the cathode. At this time, the back pressure at the gas outlet of the cell was set to 0.1 MPaG. Each source gas was humidified by passing the gas through a bubbler. The water temperature of the hydrogen bubbler was 45 ° C., and the water temperature of the air bubbler was 55 ° C. Here, the hydrogen gas flow rate was 529 mL / min, and the air gas flow rate was 1665 mL / min. The current density at a cell potential of 0.2 V was 1.5 A / cm. The cell potential at a current density of 0.5 A / cm was 0.59V.

Ｍｎ ４．５×１０⁴
イオン交換容量の実測値 １．１１ ｍｅｑ／ｇ
製膜：ＤＭＡｃ溶液キャスト法 ２０μｍ
プロトン伝導度 ７．８１×１０^-3 Ｓ／ｃｍ
吸水率 ４１％
ｍ２／（ｎ２＋ｍ２）＝０．１４ Comparative Example 3
(Synthesis of copolymer G)
A polymer electrolyte membrane comprising a copolymer G represented by the following formula was obtained in the same manner as Example 3 of JP-A-10-021943.
In addition, n2 and m2 represent the molar ratio of each structural unit of a random copolymer type polymer electrolyte.
[Copolymer G]

Mn 4.5 × 10 ⁴
Measured value of ion exchange capacity 1.11 meq / g
Film formation: DMAc solution casting method 20 μm
Proton conductivity 7.81 × 10 ⁻³ S / cm
Water absorption 41%
m2 / (n2 + m2) = 0.14

[Manufacture of catalyst paste]
A uniform copolymer B solution (concentration of copolymer A; 5% by weight) was prepared by mixing 9.5 g of NMP and 0.5 g of copolymer G. Separately, 0.64 g of platinum-supported carbon (SA50BK, manufactured by N.E. Chemcat; 50% by weight of platinum) was added to 11 mL of ethanol, and 1.05 g of the previously prepared copolymer A solution was added. The obtained mixture was subjected to ultrasonic treatment for 1 hour and then stirred for 6 hours with a stirrer to obtain catalyst ink B.

[Manufacture of polymer electrolyte membranes]
The polymer electrolyte membrane made of a block copolymer type polymer electrolyte used in Example 5 was used.

[MEA]
A carbon cloth as a gas diffusion layer was cut into a square shape and set on a heating stage, and the catalyst ink B was applied to a 5.2 cm square area at the center of the carbon cloth main surface by a spray method. The distance from the discharge port to the film was set to 5 cm, and the stage temperature was set to 76 ° C. After coating, the solution was left on the stage for 3 minutes to remove the solvent and form a catalyst layer. Two carbon cloths on which a catalyst layer was formed by this method were produced. The platinum amount of the catalyst layer determined from the weight composition of the catalyst layer and the weight of the applied catalyst layer was 0.6 mg / cm ² . Thereafter, in order to remove NMP remaining in the carbon cloth, it was immersed in 1N hydrochloric acid for 1 hour, and then washed with water for 1 hour. The electrolyte membrane was sandwiched between two carbon cloths from which NMP was removed and pressed at 120 ° C. and 10 kgf / cm ² for 15 minutes to complete the membrane-electrode assembly.

[Assembly of fuel cell evaluation cell]
A fuel cell was manufactured using a commercially available JARI standard cell. That is, a carbon separator having a gas passage groove cut in both gas diffusion layers of the membrane-electrode assembly obtained above, and a current collector and an end plate are sequentially arranged on the outside thereof. By fastening these with bolts, a fuel cell having an effective membrane area of 25 cm ² was assembled.

[Fuel cell evaluation]
While keeping the obtained fuel cells at 80 ° C., humidified hydrogen was supplied to the anode and humidified air was supplied to the cathode. At this time, the back pressure at the gas outlet of the cell was set to 0.1 MPaG. Each source gas was humidified by passing the gas through a bubbler. The water temperature of the hydrogen bubbler was 45 ° C., and the water temperature of the air bubbler was 55 ° C. Here, the hydrogen gas flow rate was 529 mL / min, and the air gas flow rate was 1665 mL / min. The cell density was 1.1 A / cm at 0.2V. The cell potential at a current density of 0.5 A / cm was 0.44 V.

Claims (15)

A copolymer obtained by mixing and condensing monomers represented by the following (A), (B), (C) and (D).
(A) Monomer having two leaving groups in the molecule and further having at least one acid group (B) Monomer having two nucleophilic groups in the molecule and further having at least one acid group (C ) Monomer having two leaving groups in the molecule and having substantially no acid group (D) Monomer having two nucleophilic groups in the molecule and having substantially no acid group The copolymer according to claim 1, wherein (A) contains a compound represented by the following formula (1).

(In the formula, k represents 0, 1 or 2, Ar ¹ and Ar ² each independently represents a divalent aromatic group, and when k is 2, two Ar ^{2 s} are the same as or different from each other. Here, these divalent aromatic groups may have a C1-C10 alkyl group which may have a substituent, a C1-C10 alkoxy group which may have a substituent, a substitution The aryl group having 6 to 10 carbon atoms which may have a group, the aryloxy group having 6 to 10 carbon atoms which may have a substituent, a fluoro group, a nitro group or a benzoyl group may be substituted. Ar ¹ is 0 when k, and Ar ¹ or Ar ² has at least one acid group when k is 1 or more, X ¹ is a fluoro group, a chloro group, a nitro group or trifluoromethane. Represents any of the sulfonyloxy groups, and two X ¹ may be the same as or different from each other, Z ¹ is a group selected from the following group, and when k is 2, two Z ¹ may be the same or different from each other.

The copolymer according to claim 1 or 2, wherein (B) comprises a compound represented by the following formula (2).

(Wherein j represents 0, 1 or 2, Ar ³ and Ar ⁴ each independently represent a divalent aromatic group, and when j is 2, two Ar ^{4 s} may be the same or different from each other. Here, these divalent aromatic groups are an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, and a substituent. Or an aryloxy group having 6 to 10 carbon atoms which may have a substituent, or an aryloxy group having 6 to 10 carbon atoms which may have a substituent, and when j is 0, Ar ³ is If j is 1 or more, any of Ar ^3, Ar ⁴ are the .Y ¹ having at least one acid group, a hydroxyl group, a thiol group, or an amino group, the two Y ¹ are each It is the same, or different may .Q ¹ also be a direct bond, and the following groups It represents et chosen group, when j is 2, two Q ¹ is also the same as each other or may be different.)

The copolymer in any one of Claims 1-3 in which the said (C) contains the compound shown by following formula (3).

(In the formula, m represents 0, 1 or 2, Ar ⁵ and Ar ⁶ each independently represent a divalent aromatic group, and when m is 2, two Ar ⁶ are the same as or different from each other. Here, these divalent aromatic groups are an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, and a substituent. also aryl group having 6 to 10 carbon atoms having a may also have a substituent aryloxy group having 6 to 10 carbon atoms, a fluoro group, optionally .X ² be substituted by nitro group or a benzoyl group Selected from a fluoro group, a chloro group, a nitro group or a trifluoromethanesulfonyloxy group, the two X ^{2 s} may be the same or different from each other, Z ² is selected from the following group, and when m is 2, One of even Z ² are the same as each other, different It may be.)

The copolymer according to any one of claims 1 to 4, wherein (D) comprises a compound represented by the following formula (4).

(In the formula, n represents 0, 1 or 2, Ar ⁷ and Ar ⁸ each independently represents a divalent aromatic group, and when n is 2, two Ar ⁸ are the same as or different from each other. Here, these divalent aromatic groups are an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, and a substituent. It may be substituted with an aryl group having 6 to 10 carbon atoms, which may have a substituent, or an aryloxy group having 6 to 10 carbon atoms, which may have a substituent, and Y ² is a phenolic hydroxyl group, a thiol group or an amino group. And two Y ^{2 s} may be the same or different from each other, Q ² is a direct bond or a group selected from the following group, and when n is 2, two Q ^{2 s} may be the same as each other , May be different.)

6. The copolymer according to claim 1, wherein the acid group is a strong acid group or a super strong acid group. The copolymer according to any one of claims 1 to 6, wherein the ion exchange capacity is 0.1 meq / g to 4.0 meq / g. In the copolymer, the weight composition ratio of the structural unit in which the acid group is introduced to the structural unit in which the acid group is not substantially introduced is [structural unit into which the acid group has been introduced]: [acid group is substantial. The copolymer according to any one of claims 1 to 7, wherein the copolymer is 3:97 to 70:30. The polymer electrolyte containing the copolymer in any one of Claims 1-8. A polymer electrolyte membrane comprising the polymer electrolyte according to claim 9. A polymer electrolyte composite membrane, wherein the polymer electrolyte according to claim 9 is impregnated into a porous substrate to form a composite. A catalyst composition comprising the polymer electrolyte according to claim 9 and a catalyst substance. A fuel cell comprising the polymer electrolyte membrane according to claim 10. A fuel cell comprising the polymer electrolyte composite membrane according to claim 11. A fuel cell comprising a catalyst layer obtained from the catalyst composition according to claim 13.