JP5350974B2 - Membrane-electrode structure for polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane-electrode structure for solid polymer fuel cell, having a proton conductive film which is superior in proton conductivity. <P>SOLUTION: The membrane-electrode structure for solid polymer fuel cell contains sulfonated polyarylene which contains a structural unit having a proton conductive group expressed by formula (1a) and a structural unit, having a heterocycle structure containing nitrogen as expressed in formula (2a) in a main chain. In the formula (2a), Ar<SP>31</SP>indicates a heterocycle containing nitrogen. Among single lines at the end part of the structural unit, one which does not indicate a substituent on one side means a connection with a neighboring structural unit. In the formula (1a), Y indicates, at least one kind of structure selected from the group of -CO-, -SO2-, -SO-, -CONH-, -COO-, -(CF<SB>2</SB>)<SB>1</SB>- (I is an integer of 1-10), and -C(CF<SB>3</SB>)<SB>2</SB>-; Z indicates at least one kind of structure selected from the group of a direct bond, or -(CH<SB>2</SB>)<SB>1</SB>- (I is an integer of 1-10), -C(CH<SB>3</SB>)<SB>2</SB>-, -O-, and -S-; Ar indicates an aromatic group having a substituent as expressed by -SO<SB>3</SB>H, -O(CH<SB>2</SB>)<SB>p</SB>SO<SB>3</SB>H, or -O(CF<SB>2</SB>)<SB>p</SB>SO<SB>3</SB>H (p is an integer of 1-12). Also m indicates an integer of 0-10, n indicates an integer of 1-10, and k indicates an integer of 1-4. Among the single lines at the end part of the structural unit, one which does not indicate a substituent on one side means a connection with the neighboring structural unit. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a membrane-electrode structure for a polymer electrolyte fuel cell.

  A fuel cell is a power generation system that has high power generation efficiency and a low burden on the environment because of less emissions. Fuel cells are in the limelight with the recent growing interest in protecting the global environment and moving away from dependence on fossil fuels. Fuel cells are expected to be installed in small distributed power generation facilities, power generation devices as driving sources for moving objects such as automobiles and ships, or mobile phones or mobile personal computers that replace secondary batteries such as lithium ion batteries. ing.

  A polymer electrolyte fuel cell is provided with a pair of electrodes on both sides of a proton-conducting solid polymer electrolyte membrane (hereinafter referred to as “proton-conducting membrane”). To the other electrode (air electrode) using oxygen gas or air as an oxidant to obtain an electromotive force.

  Conventionally, proton conductive membranes are commercially available under the trade names Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Kogyo Co., Ltd.), or Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.). Perfluorosulfonic acid-based membranes have been used because of their excellent chemical stability.

  However, since perfluorosulfonic acid membranes such as Nafion are difficult to manufacture, there is a problem that they are very expensive, and are widely used in consumer applications such as fuel cell vehicles and household fuel cell power generation systems. It has become a major obstacle. Further, these perfluorosulfonic acid membranes have a large amount of fluorine atoms in the molecule, and therefore, are difficult to dispose of after use from the viewpoint of environmental protection.

  Further, the higher the temperature of the fuel cell and the thinner the proton conducting membrane between the electrodes, the lower the membrane resistance and the higher the power generation output. However, these perfluorosulfonic acid membranes have a heat distortion temperature of about 80 to 100 ° C. and have very poor creep resistance at high temperatures. For this reason, when these membranes are used in a fuel cell, the power generation temperature must be kept at 80 ° C. or lower, and the power generation output is limited. Further, the film thickness is poor when used for a long period of time, and in order to prevent a short circuit between the electrodes, a certain film thickness (50 μm or more) is necessary, and it is difficult to reduce the film thickness.

  In order to solve the above-mentioned problems with perfluorosulfonic acid membranes, hydrocarbon proton conductive membranes that do not contain fluorine atoms, are cheaper, and have a heat-resistant main chain skeleton that is also used for engineer plastics are currently available. Many studies have been conducted. For example, a polymer in which a main chain aromatic ring of polyarylene, polyether ether ketone, polyether sulfone, polyphenylene sulfide, polyimide, or polybenzazole is sulfonated has been proposed (Non-Patent Documents 1 to 3). reference).

Polymer Preprints, Japan, Vol. 42, no. 7, p. 2490-2492 (1993) Polymer Preprints, Japan, Vol. 43, no. 3, p. 735-736 (1994) Polymer Preprints, Japan, Vol. 42, no. 3, p. 730 (1993)

However, in an actual fuel cell, a side reaction occurs simultaneously with a main reaction, and a representative one is a hydrogen peroxide (H ₂ O ₂ ) formation reaction. The radical species resulting from the hydrogen peroxide deteriorates the hydrocarbon proton conductive membrane as described above, causing a decrease in proton conductivity.

  The object of the present invention is to improve the cross-link resistance under a dry environment and the swelling property under hydrothermal conditions, and thus the problems of the fluorine-based proton conductive membrane and the aromatic-based proton conductive membrane that have been studied conventionally. It is an object of the present invention to provide a membrane-electrode structure for a polymer electrolyte fuel cell comprising a proton conducting membrane excellent in proton conductivity.

As a result of intensive studies to achieve the above object, the present inventors have found that a proton conductive membrane having a heterocyclic ring containing nitrogen in the main chain is a novel material that satisfies the object of the present invention, The present invention has been completed.
That is, the gist of the present invention is as follows.

［式（１ａ）中、Ｙは、−ＣＯ−、−ＳＯ_２−、−ＳＯ−、−ＣＯＮＨ−、−ＣＯＯ−、−（ＣＦ_２）_ｌ−（ｌは１〜１０の整数である）、及び−Ｃ（ＣＦ_３）_２−からなる群より選ばれる少なくとも１種の構造を示し、Ｚは、直接結合、または、−（ＣＨ_２）_ｌ−（ｌは１〜１０の整数である）、−Ｃ（ＣＨ_３）_２−、−Ｏ−、及び−Ｓ−からなる群より選ばれる少なくとも１種の構造を示し、Ａｒは、−ＳＯ_３Ｈ、−Ｏ（ＣＨ_２）_ｐＳＯ_３Ｈ、または−Ｏ（ＣＦ_２）_ｐＳＯ_３Ｈ（ｐは１〜１２の整数である）で表される置換基を有する芳香族基を示す。芳香族基は、ベンゼン環、または縮合芳香族環を示す。ｍは０〜１０の整数を示し、ｎは０〜１０の整数を示し、ｋは１〜４の整数を示す。構造単位の端部における単線のうち、一方に置換基が表示されていないものは隣り合う構造単位との接続を意味する。］

［式（２ａ）中、Ａｒ^３１は、窒素を含む複素環を示す。構造単位の端部における単線のうち、一方に置換基が表示されていないものは隣り合う構造単位との接続を意味する。］ The membrane-electrode structure for a polymer electrolyte fuel cell according to claim 1, wherein the proton conductive membrane has an anode electrode on one surface and a cathode electrode on the other surface. In the body, the proton conductive membrane has a structural unit having a proton conductive group represented by the following general formula (1a) and a heterocyclic structure containing nitrogen represented by the following general formula (2a) in the main chain. And a sulfonated polyarylene containing a structural unit.

[In the formula (1a), Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) ₁ — (l is an integer of 1 to 10), And at least one structure selected from the group consisting of —C (CF ₃ ) ₂ —, Z is a direct bond, or — (CH ₂ ) ₁ — (l is an integer of 1 to 10), 1 represents at least one structure selected from the group consisting of —C (CH ₃ ) ₂ —, —O—, and —S—, and Ar represents —SO ₃ H, —O (CH ₂ ) _p SO ₃ H, or _{-O (CF 2) p SO 3} H (p is a is an integer of 1 to 12) represents an aromatic group having a substituent represented by. The aromatic group represents a benzene ring or a condensed aromatic ring. m shows the integer of 0-10, n shows the integer of 0-10, k shows the integer of 1-4. Among the single lines at the end of the structural unit, those not having a substituent displayed on one side mean connection with the adjacent structural unit. ]

[In formula (2a), Ar ³¹ represents a heterocyclic ring containing nitrogen. Among the single lines at the end of the structural unit, those not having a substituent displayed on one side mean connection with the adjacent structural unit. ]

［式（３ａ）中、Ａ及びＤは独立に、直接結合、または、−ＣＯ−、−ＳＯ_２−、−ＳＯ−、−（ＣＦ_２）_ｌ−（ｌは１〜１０の整数である）、−Ｃ（ＣＦ_３）_２−、−（ＣＨ_２）_ｌ−（ｌは１〜１０の整数である）、−ＣＲ’_２−（Ｒ’は脂肪族炭化水素基、芳香族炭化水素基、またはハロゲン化炭化水素基を示す）、−Ｏ−、−Ｓ−、シクロヘキシリデン基、及びフルオレニリデン基からなる群より選ばれる少なくとも１種の構造を示し、Ｂは独立に、酸素原子または硫黄原子であり、Ｒ^１〜Ｒ^１６は、互いに同一でも異なっていてもよく、水素原子、フッ素原子、アルキル基、一部または全てがハロゲン化されたハロゲン化アルキル基、アリル基、アリール基、ニトロ基、及びニトリル基からなる群より選ばれる少なくとも１種の原子または基を示す。ｓ及びｔは０〜４の整数を示し、ｒは０以上の整数を示す。構造単位の端部における単線のうち、一方に置換基が表示されていないものは隣り合う構造単位との接続を意味する。］ The invention according to claim 2 is the membrane-electrode structure for a polymer electrolyte fuel cell according to claim 1, wherein the sulfonated polyarylene has an aromatic structure represented by the following general formula (3a). A structural unit is further contained in the main chain.

[In the formula (3a), A and D are independently a direct bond, or —CO—, —SO ₂ —, —SO—, — (CF ₂ ) ₁ — (l is an integer of 1 to 10). , —C (CF ₃ ) ₂ —, — (CH ₂ ) ₁ — (l is an integer of 1 to 10), —CR ′ ₂ — (R ′ is an aliphatic hydrocarbon group, an aromatic hydrocarbon group, Or a halogenated hydrocarbon group), at least one structure selected from the group consisting of —O—, —S—, a cyclohexylidene group, and a fluorenylidene group, 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 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. , And at least selected from the group consisting of nitrile groups Indicating the kind of atom or group. s and t represent an integer of 0 to 4, and r represents an integer of 0 or more. Among the single lines at the end of the structural unit, those not having a substituent displayed on one side mean connection with the adjacent structural unit. ]

［式（２ｂ）中、構造単位の端部における単線のうち、一方に置換基が表示されていないものは隣り合う構造単位との接続を意味する。］ The invention according to claim 3 is the membrane-electrode structure for a polymer electrolyte fuel cell according to claim 1 or 2, wherein Ar ³¹ in the formula (2a) is 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, benzoxazole, 1,3,5-triazine, bromine, tetrazole, tetrazine, triazole, phenalsazine, benzimidazole, benzotriazole, thiazole, benzothiazole, and benzo It includes at least one structure selected from the group consisting of a structure derived from at least one selected from the group consisting of thiadiazole or a structure represented by the following chemical formula (2b).

[In the formula (2b), among the single wires at the end of the structural unit, one on which no substituent is displayed means connection with an adjacent structural unit. ]

  According to the membrane-electrode structure for a polymer electrolyte fuel cell of the present invention, by containing a heterocyclic ring containing nitrogen in the main chain of the proton conducting membrane, the proton conductivity is reduced in hot water without lowering the proton conductivity. Swelling can be suppressed, and heat resistance can be improved.

  Hereinafter, the present invention will be described in detail.

The sulfonated polyarylene used in the present invention has a structural unit having a proton conductive group and a structural unit having a nitrogen-containing heterocyclic structure in the main chain.
Furthermore, the sulfonated polyarylene used in the present invention preferably has a structural unit having an aromatic structure in the main chain.

[Structural unit having proton conductive group]
The structural unit having a proton conductive group is represented by the following general formula (1a). The structural unit having a proton conductive group is preferably a structural unit having a sulfonic acid group.

In the above formula (1a), Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) ₁ — (l is an integer of 1 to 10), And at least one structure selected from the group consisting of —C (CF ₃ ) ₂ —, Z is a direct bond, or — (CH ₂ ) ₁ — (l is an integer of 1 to 10), 1 represents at least one structure selected from the group consisting of —C (CH ₃ ) ₂ —, —O—, and —S—, and Ar represents —SO ₃ H, —O (CH ₂ ) _p SO ₃ H, or _{-O (CF 2) p SO 3} H (p is a is an integer of 1 to 12) represents an aromatic group having a substituent represented by. The aromatic group represents a benzene ring or a condensed aromatic ring. m shows the integer of 0-10, n shows the integer of 0-10, k shows the integer of 1-4.

Specific examples of the structural unit having a sulfonic acid group include the following.

  In the sulfonated polyarylene used in the present invention, a structural unit having a sulfonic acid group of the proton conductive group as described above is included in the main chain together with a structural unit having a nitrogen-containing heterocyclic structure, which will be described later. Proton conductivity is obtained.

[Structural units having a heterocyclic structure containing nitrogen]
The structural unit having a heterocyclic structure containing nitrogen is represented by the following general formula (2a).

Ar ³¹ in the above formula (2a) represents a nitrogen-containing heterocyclic ring, specifically, 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, isoi At least one selected from the group consisting of endrin, quinuclidine, oxazole, benzoxazole, 1,3,5-triazine, bryne, tetrazole, tetrazine, triazole, phenalsazine, benzimidazole, benzotriazole, thiazole, benzothiazole, and benzothiadiazole Or at least one structure selected from the group consisting of structures represented by the following chemical formula (2b).

  Of the above, pyrrole, pyridine, pyrimidine, quinoline, isoquinoline, quinoxaline, phthalazine, naphthyridine, phenanthroline, phenazine, benzimidazole, benzotriazole, thiazole, benzothiadiazole, and the structure represented by the above formula (2b) are particularly preferable. .

  In the sulfonated polyarylene used in the present invention, a proton having a structural unit having a nitrogen-containing heterocyclic structure as described above in the main chain together with the structural unit having a sulfonic acid group of the proton conductive group described above is used. Without lowering the conductivity, swelling in hot water can be suppressed and heat resistance can be improved.

[Structural unit having aromatic structure]
The structural unit having an aromatic structure is represented by the following general formula (3b).

In the above formula (3b), Ar ²¹ , Ar ²² , Ar ²³ , and Ar ²⁴ each independently represent a divalent group having a benzene ring, condensed aromatic ring, or nitrogen-containing heterocyclic structure.
However, Ar ²¹ , Ar ²² , Ar ²³ , and Ar ²⁴ are partly or entirely selected from the group consisting of a fluorine atom, a nitro group, a nitrile group, an alkyl group, an allyl group, and an aryl group. It may be substituted with at least one atom or group. Further, in the above alkyl group, some or all of the hydrogen atoms may be halogenated.

A and D are each independently a direct bond, —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (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, or a halogenated hydrocarbon group. ), A cyclohexylidene group, a fluorenylidene group, -O-, or S-, and B is an oxygen atom or a sulfur atom.
s and t each independently represent an integer of 0 to 4, and r represents an integer of 0 or more.

As the structural unit having an aromatic structure, those represented by the following general formula (3a) are preferable.

In the above formula (3a), A and D are independently a direct bond, or —CO—, —SO ₂ —, —SO—, — (CF ₂ ) ₁ — (l is an integer of 1 to 10). , —C (CF ₃ ) ₂ —, — (CH ₂ ) ₁ — (l is an integer of 1 to 10), —CR ′ ₂ — (R ′ is an aliphatic hydrocarbon group, an aromatic hydrocarbon group, Or a halogenated hydrocarbon group), at least one structure selected from the group consisting of —O—, —S—, a cyclohexylidene group, and a fluorenylidene group, and B is independently an oxygen atom or a sulfur atom It is.
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 partially or wholly halogenated, an allyl group, an aryl group, a nitro group, and a nitrile. At least one atom or group selected from the group consisting of groups is shown.
s and t represent an integer of 0 to 4, and r represents an integer of 0 or more.

Specific examples of the structural unit having an aromatic structure include the following.

  By containing the structural unit having the aromatic structure as described above, the hydrophobicity of the sulfonated polyarylene is remarkably improved. For this reason, the swelling in hot water can be suppressed and heat resistance can be imparted while having proton conductivity similar to that of the prior art.

[Sulfonated polyarylene]
The sulfonated polyarylene used in the present invention is represented by the following general formula (4). The main chain in the present invention is a long chain portion in which repeating units are connected by polymerization, and the side chain is a portion that is branched from the main chain.

In the above general formula (4), A, B, D, Y, Z, Ar ¹¹ , Ar ¹² , Ar ¹³ , Ar ^{21 to} Ar ²⁴ , Ar ³¹ , a, b, s, t, r, x ¹ , x ² and R ^{11 to} R ¹³ are A, B, D, Y, Z, Ar ¹¹ , Ar ¹² , Ar ¹³ , Ar ^{21 to} Ar ²⁴ , Ar ³¹ , a, b, s in the above general formula, respectively. , T, r, x ¹ , x ² , and R ^{11 to} R ¹³ . x, y, and z show molar ratios when x + y + z = 100 mol%.

  The number of moles of the structural unit represented by the general formula (1a) contained in 1 mole of the sulfonated polyarylene used in the present invention is (x), and the number of moles of the structural unit represented by the general formula (2a) is (y). When the number of moles of the structural unit represented by the general formula (3a) is (z), the value of (x) / {(x) + (y) + (z)} × 100 (mol%) is Preferably it is 0.05-100. More preferably, it is 0.5-99.9, Most preferably, it is 1-90.

  Moreover, the value of (y) / {(x) + (y) + (z)} × 100 (mol%) is preferably 0.05 to 99.95. When the number of moles (y) of the structural unit represented by the general formula (2a) is in the above range in the sulfonated polyarylene of the present invention, the proton conductive membrane obtained from the sulfonated polyarylene has hydrothermal conditions. It is preferable because it is excellent in suppressing swelling under the surface and suppressing area change, and is excellent in cross-linking resistance under high temperature conditions. More preferably, it is 0.1-99, Most preferably, it is 0.5-90.

  Further, the ratio (y) / (x) of the structural unit represented by the general formula (2a) and the structural unit represented by the general formula (1a) is preferably 0.01 to 20. When the ratio between the structural unit represented by the general formula (2a) and the structural unit represented by the general formula (1a) is within the above range, the proton conducting membrane obtained from the sulfonated polyarylene has a proton conductivity. It is preferable because swelling in hot water can be suppressed and heat resistance can be improved without lowering. More preferably, it is 0.1-15, Most preferably, it is 0.5-10.

  Further, the value of (z) / {(x) + (y) + (z)} × 100 (mol%) is preferably 0 to 99.5, more preferably 0.01 to 99, Especially preferably, it is 0.1-98.

  The molecular weight of the sulfonated polyarylene used in the present invention is preferably 10,000 to 1,000,000 in terms of polystyrene-reduced weight average molecular weight by gel permeation chromatography (GPC). More preferably, it is 20,000-800,000, Most preferably, it is 50,000-300,000.

  The ion exchange capacity of the sulfonated polyarylene used in the present invention is preferably 0.5 to 3.5 meq / g. More preferably, it is 0.5-3.0 meq / g, Most preferably, it is 0.8-2.8 meq / g. An ion exchange capacity of 0.5 meq / g or more is preferable because a proton conductive membrane having high proton conductivity and high power generation performance can be obtained. On the other hand, if it is 3.5 meq / g or less, it is preferable because sufficiently high water resistance can be provided.

The above 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, when the number of structural units having a sulfonic acid group of the proton conductive group increases in the sulfonated polyarylene, the ion exchange capacity increases and the proton conductivity increases, but the water resistance tends to decrease. On the other hand, when these structural units decrease, the ion exchange capacity decreases and the water resistance increases, but the proton conductivity tends to decrease.

[Method for producing sulfonated polyarylene]
The sulfonated polyarylene used in the present invention can be produced by using, for example, the following three methods: Method A1, Method B1, or Method C1.

(A1 method)
For example, by a method similar to the method described in JP-A No. 2004-137444, a sulfonate ester serving as a structural unit having a sulfonic acid group of a proton conductive group and a structural unit having a heterocyclic structure containing nitrogen are obtained. A monomer and, if necessary, a monomer or oligomer that becomes a structural unit having an aromatic structure are copolymerized to produce a polyarylene having a sulfonate group. Subsequently, it can manufacture by deesterifying this sulfonate group and converting each sulfonate group into a sulfonate group.

(1) Structural unit having a sulfonic acid group A structural unit having a sulfonic acid group of a proton conductive group is, for example, a sulfonic acid ester represented by the following general formula (1d) as a polymerization raw material of a sulfonated polyarylene. It can be manufactured by use.

In the general formula (1d), Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) ₁ — (l is an integer of 1 to 10). , —C (CF ₃ ) ₂ —, and at least one structure selected from the group consisting of direct bonds. Of these, —CO—, —SO ₂ —, and a direct bond are preferable.
Z is a direct bond or selected from the group consisting of — (CH ₂ ) ₁ — (wherein 1 is an integer of 1 to 10), —C (CH ₃ ) ₂ —, —O—, and —S—. At least one structure is shown. Of these, a direct bond, —O—, or —S— is preferable.
X is at least one selected from the group consisting of 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). Indicates an atom or group of species. Of these, chlorine and bromine are preferred.

In the general formula (1d), Ar represents an aromatic group having a substituent represented by —SO ₃ Rc, —O (CH ₂ ) _p SO ₃ Rc, or —O (CF ₂ ) _p SO ₃ Rc. Show. p shows the integer of 1-12, More preferably, it is an integer of 1-10, More preferably, it is an integer of 1-6. Rc represents a hydrocarbon group having 1 to 20 carbon atoms in which some of the carbon atoms may be replaced with oxygen atoms. More preferably, it is a hydrocarbon group having 4 to 20 carbon atoms in which some of the carbon atoms may be replaced by oxygen atoms.
Specifically, as Rc, methyl group, ethyl group, n-propyl group, iso-propyl group, tert-butyl group, iso-butyl group, n-butyl group, sec-butyl group, neopentyl group, cyclopentyl group Hexyl group, cyclohexyl group, cyclopentylmethyl group, cyclohexylmethyl group, adamantyl group, adamantanemethyl group, 2-ethylhexyl group, bicyclo [2.2.1] heptyl group, bicyclo [2.2.1] heptylmethyl group A linear hydrocarbon group such as a tetrahydrofurfuryl group, a 2-methylbutyl group, a 3,3-dimethyl-2,4-dioxolanemethyl group, an adamantylmethyl group, a branched hydrocarbon group, an alicyclic hydrocarbon group, Examples thereof include a hydrocarbon group having a 5-membered heterocyclic ring. Among these, n-butyl group, neopentyl group, tetrahydrofurfuryl group, cyclopentyl group, cyclohexyl group, cyclohexylmethyl group, adamantylmethyl group, and bicyclo [2.2.1] heptylmethyl group are preferable, and neopentyl group is particularly preferable. .

  In the general formula (1d), R represents a hydrocarbon group having 1 to 20 carbon atoms in which some of the carbon atoms may be replaced by oxygen atoms. More preferred is a hydrocarbon group having 4 to 20 carbon atoms. Specifically, methyl group, ethyl group, n-propyl group, iso-propyl group, tert-butyl group, iso-butyl group, n-butyl group, sec-butyl group, neopentyl group, cyclopentyl group, hexyl group, Cyclohexyl group, cyclopentylmethyl group, cyclohexylmethyl group, adamantyl group, adamantanemethyl 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-dioxolanemethyl group, linear hydrocarbon group such as adamantylmethyl group, branched hydrocarbon group, alicyclic hydrocarbon group, 5-membered Examples thereof include a hydrocarbon group having a heterocyclic ring. Among these, n-butyl group, neopentyl group, tetrahydrofurfuryl group, cyclopentyl group, cyclohexyl group, cyclohexylmethyl group, adamantylmethyl group, and bicyclo [2.2.1] heptylmethyl group are preferable, and neopentyl group is particularly preferable. .

In the general formula (1d), m represents an integer of 0 to 10, preferably an integer of 0 to 5, more preferably an integer of 0 to 3.
n represents an integer of 0 to 10, preferably an integer of 0 to 5, more preferably an integer of 0 to 3.
k shows the integer of 1-4, Preferably the integer of 1-3 is shown, More preferably, the integer of 1-2 is shown.

In the general formula (1d), examples of preferable combinations of Y, Z, m, n, and k include the following combinations.
(1) A structure in which m = 1, n = 0, Y = —CO—, and Z = —O—.
(2) A structure in which m = 1, n = 1, k = 1, Y = —CO—, and Z = —O—.
(3) A structure in which m = 0, n = 1, k = 1, Y = —CO—, and Z = —O—.
(4) A structure in which m = 0, n = 1, k = 1, Y = —CO—, and Z is a direct bond,
(5) A structure in which m = 0, n = 0, and Y = —CO—.
(6) A structure in which m = 0, n = 0, and Y is a direct bond.

Specific examples of the compound represented by the general formula (1d) include compounds represented by the following chemical formulas, JP-A Nos. 2004-137444, 2004-345997, and 2004-346163. Can be mentioned.

Of the above compounds, compounds having a protecting group of neopentyl alcohol, isopropyl alcohol, and furfuryl alcohol are preferred.
Compound chlorine atom is replaced with a bromine atom in the compound, -CO- is -SO 2 _- may also be mentioned compounds replaced the like. In addition, isomers having different bonding positions of chlorine atoms and bromine atoms can also be mentioned.

(2) Structural unit having a nitrogen-containing heterocyclic structure In order to produce a sulfonated polyarylene having a structural unit having a nitrogen-containing heterocyclic structure, for example, a compound represented by the following general formula (2c) is prepared. Can be used.

In the general formula (2c), ^{Ar 31} has the same meaning as ^{Ar 31} in the general formula (2a).
X represents an atom or group selected from halogen atoms excluding fluorine (chlorine, bromine, iodine), —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.

Specific examples of the monomer represented by the general formula (2c) include the following.

  Examples of the compound include a compound in which a chlorine atom is replaced with a bromine atom, and a compound in which a bromine atom is replaced with a chlorine atom. In addition, isomers having different bonding positions of chlorine atoms and bromine atoms can also be mentioned.

(3) Structural unit having an aromatic structure The structural unit having an aromatic structure can be obtained, for example, by preparing an oligomer represented by the following general formula (3c) and polymerizing it.

In the general formula (3c), Ar ²¹ , Ar ²² , Ar ²³ , and Ar ²⁴ represent at least one structure selected from the group consisting of a benzene ring, a naphthalene ring, and a nitrogen-containing heterocyclic ring. However, Ar ²¹ , Ar ²² , Ar ²³ , and Ar ²⁴ are partly or entirely selected from the group consisting of a fluorine atom, a nitro group, a nitrile group, an alkyl group, an allyl group, and an aryl group. It may be substituted with at least one atom or group. Further, in the above alkyl group, some or all of the hydrogen atoms may be halogenated.

In the general formula (3c), 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 each independently a direct bond or —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (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 ′ is an aliphatic hydrocarbon group, aromatic hydrocarbon group, or halogenated hydrocarbon) Group), at least one structure selected from the group consisting of cyclohexylidene group, fluorenylidene group, -O-, and -S-, and B is independently an oxygen atom or a sulfur atom.
s and t represent an integer of 0 to 4, and r represents an integer of 0 or more.

The structural unit having an aromatic structure can be obtained by using, for example, an oligomer represented by the following general formula (3d) as a polymerization raw material for the sulfonated polyarylene.

In the general formula (3d), A and D are each independently a direct bond, or —CO—, —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 ′ is an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a halogenated hydrocarbon group. ), At least one structure selected from the group consisting of a cyclohexylidene group, a fluorenylidene group, -O-, and -S-.
Here, specific examples of the structure represented by -R'- include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, propyl group, octyl group, decyl group, An octadecyl group, a phenyl group, a trifluoromethyl group, etc. are mentioned.
As A and D, among the above, a direct bond, or —CO—, —SO ₂ —, —CR ′ ₂ — (R ′ is an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a halogenated hydrocarbon. A cyclohexylidene group, a fluorenylidene group, and -O- are preferred.

In the general formula (3d), B is independently an oxygen atom or a sulfur atom, preferably an oxygen atom.
R ^{1 to} R ¹⁶ may be the same as or different from each other, and may be a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group partially or wholly halogenated, an allyl group, an aryl group, a nitro group, or a nitrile group. At least one atom or group selected from the group consisting of
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a hexyl group, a cyclohexyl group, and an octyl group. Examples of the halogenated 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.
s and t show the integer of 0-4. r shows an integer greater than or equal to 0, and an upper limit is 100 normally, Preferably it is 1-80.
X represents an atom or group selected from halogen atoms excluding fluorine (chlorine, bromine, iodine), —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.

Preferred combinations of the values of s and t and the structures of A, B, D and R ^{1 to} R ¹⁶ include the following combinations.
(1) s = 1, t = 1, A is —CR ′ ₂ — (R ′ represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a halogenated hydrocarbon group), a cyclohexylidene group Or a fluorenylidene group, B is an oxygen atom, D is -CO-, or -SO _2- , and R ^{1 to} R ¹⁶ are hydrogen atoms or fluorine atoms,
(2) a structure in which s = 1, t = 0, B is an oxygen atom, D is —CO— or —SO ₂ —, and R ^{1 to} R ¹⁶ are a hydrogen atom or a fluorine atom,
(3) s = 0, t = 1, and A is —CR ′ ₂ — (R ′ represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a halogenated hydrocarbon group), a cyclohexylidene group , A fluorenylidene group, B is an oxygen atom, and R ^{1 to} R ¹⁶ are a hydrogen atom, a fluorine atom, or a nitrile group,
(4) s = 1, t = 1, 2 and A is —C (CF ₃ ) ₂ —, or —C (CR ′ ₂ ) ₂ — (R ′ is a hydrocarbon group or a cyclic hydrocarbon group). A structure in which B is an oxygen atom, D is —CO— or —SO ₂ —, and R ^{1 to} R ¹⁶ are a hydrogen atom or a fluorine atom,
(5) s = 0, t = 1, 2 and A is —C (CF ₃ ) ₂ —, or —C (CR ′ ₂ ) ₂ — (R ′ is a hydrocarbon group or a cyclic hydrocarbon group). Wherein B is an oxygen atom and R ^{1 to} R ¹⁶ are a hydrogen atom, a fluorine atom, or a nitrile group.

Specific examples of the oligomer represented by the general formula (3d) include the following.

  Examples include compounds in which chlorine atoms are replaced by bromine atoms in the above compounds. In addition, isomers having different bonding positions of chlorine atoms and bromine atoms can also be mentioned.

  The oligomer represented by the general formula (3d) can be produced, for example, by copolymerizing the following monomers. When r = 0 in the general formula (3d), 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, 2,6 -Dichlorobenzonitrile.

  Examples of these compounds include compounds in which a chlorine atom is replaced with a bromine atom or an iodine atom. 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. 2005-348523). No. 112985), Japanese Patent Application No. 2003-348524, Japanese Patent Application No. 2004-211739 (Japanese Patent Application Laid-Open No. 2006-28414), Japanese Patent Application No. 2004- 211740 (Japanese Patent Application Laid-Open No. 2006-28415), and the like. Can do.

(4) Polymerization of sulfonated polyarylene In order to obtain the sulfonated polyarylene used in the present invention, first, the monomer represented by the general formula (1d) which can be the structural unit represented by the general formula (1a). A monomer represented by the general formula (2c) that can be the structural unit represented by the general formula (2a), and, if necessary, a monomer or oligomer that can be the structural unit represented by the general formula (3a), The general formula (3d) is copolymerized to obtain a precursor polyarylene. This copolymerization is carried out in the presence of a catalyst, and the catalyst used here is a catalyst system containing a transition metal compound. As this catalyst system, (1) a transition metal salt and a compound that becomes a ligand (hereinafter referred to as “ligand component”), or a transition metal complex in which a ligand is coordinated (including a copper salt) (2) A reducing agent may be an essential component, and a salt other than a transition metal salt may be added to increase the polymerization rate.

  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. The ligand component includes triphenylphosphine, tri (2-methyl) phenylphosphine, tri (3-methyl) phenylphosphine, tri (4-methyl) phenylphosphine, 2,2′-bipyridine, 1,5-cycloocta Examples include diene and 1,3-bis (diphenylphosphino) propane, and triphenylphosphine, tri (2-methyl) phenylphosphine, and 2,2′-bipyridine are preferable. The said ligand component 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 Such as nickel chloride (Triphenylphosphine), nickel chloride bis (tri (2 Mechiru) phenyl phosphine), 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, calcium, and the like, and zinc, magnesium, and manganese are preferable. These reducing agents can be used after being more activated by contacting 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, sodium iodide, sodium sulfate, potassium fluoride, and potassium chloride. Potassium compounds such as potassium bromide, potassium iodide, and potassium sulfate, and ammonium compounds such as tetraethylammonium fluoride, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, and tetraethylammonium sulfate. Sodium, sodium iodide, potassium bromide, tetraethylammonium bromide and tetraethylammonium iodide are preferred.

  The proportion of each component used in the catalyst system is represented by the transition metal salt or transition metal (salt) coordinated with a ligand represented by the above general formula (1d) and the general formula (2c). The total amount of the compound and the compound represented by the general formula (3d) is usually 0.0001 to 10 mol, preferably 0.01 to 0.5 mol. When the amount is less than 0.0001 mol, the polymerization reaction does not proceed sufficiently. On the other hand, when the amount exceeds 10 mol, there is a concern that the molecular weight is lowered. In the catalyst system, when a transition metal salt and a ligand component are used, the ratio of the ligand component used is usually 0.1 to 100 mol, preferably 1 to 10 mol, relative to 1 mol of the transition metal salt. is there. If the amount is less than 0.1 mol, the catalytic activity becomes insufficient. On the other hand, if the amount exceeds 100 mol, the molecular weight may decrease.

  The ratio of the reducing agent used in the catalyst system is 1 in total of the compound represented by the general formula (1d), the compound represented by the general formula (2c), and the compound represented by the general formula (3d). It is 0.1-100 mol normally with respect to mol, Preferably it is 1-10 mol. If the amount is less than 0.1 mol, the polymerization does not proceed sufficiently. On the other hand, if the amount exceeds 100 mol, purification of the resulting polymer may be difficult.

  Further, when a salt other than the transition metal salt is used in the catalyst system, the use ratio thereof is the monomer represented by the general formula (1d) which can be the structural unit represented by the above general formula (1a), and the above general formula. Total 1 of the monomer represented by the general formula (2c) that can be the structural unit represented by (2a) and the monomer or oligomer that can be the structural unit represented by the general formula (3a), that is, the general formula (3d) Usually, it is 0.001-100 mol with respect to mol, Preferably it is 0.01-1 mol. If it is less than 0.001 mol, the effect of increasing the polymerization rate may be insufficient. On the other hand, if it exceeds 100 mol, purification of the resulting polymer may be difficult.

  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. In the polymerization solvent, a monomer represented by the general formula (1d) that can be the structural unit represented by the general formula (1a) and a general formula (2c) that can be the structural unit represented by the general formula (2a). The total concentration of the monomer represented by the above formula and the monomer or oligomer that can be the structural unit represented by the general formula (3a), that is, the general formula (3c) is usually 1 to 90% by mass, preferably 5 to 40% by mass. %.

  Moreover, the polymerization temperature at the time of superposing | polymerizing the sulfonated polyarylene used by this invention is 0-200 degreeC normally, Preferably it is 50-80 degreeC. The polymerization time is usually 0.5 to 100 hours, preferably 1 to 40 hours.

(B1 method)
For example, in the method described in JP-A No. 2001-342241, a monomer having a skeleton represented by the general formula (1d) and not having a sulfonic acid group or a sulfonic acid ester group, and the general formula (2a) A monomer represented by the general formula (2c) that can be a structural unit represented, and, if necessary, a monomer or oligomer represented by the general formula (3d) that can be a structural unit represented by the general formula (3a). It can also be synthesized by copolymerization and sulfonation of this polymer using a sulfonating agent.

(C1 method)
In the general formula (1d), when Ar is an aromatic group having a substituent represented by —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H, for example, In the method described in Japanese Patent Application No. 2003-295974 (Japanese Patent Application Laid-Open No. 2005-60625), a precursor monomer that can be a structural unit represented by the above general formula (1a), and a compound represented by the above general formula (2a) The monomer represented by the general formula (2c) that can be a structural unit can be copolymerized with the monomer or oligomer that can be the structural unit represented by the general formula (3a), if necessary, and then an alkylsulfonic acid or It can also be synthesized by a method of introducing a fluorine-substituted alkylsulfonic acid.

  In addition, the sulfonated polyarylene having a sulfonic acid group can be obtained by converting these precursor polyarylenes into a polyarylene having a sulfonic acid group. As this method, there are the following three methods.

(Method A2)
In this method, polyarylene having a sulfonate group as a precursor is deesterified by the method described in JP-A No. 2004-137444.

(Method B2)
In this method, the precursor having no sulfonic acid group or sulfonic acid ester group is sulfonated by the method described in JP-A-2001-342241.

(C2 method)
In this method, alkylsulfonic acid groups are introduced into the precursor polyarylene by the method described in Japanese Patent Application No. 2003-295974 (Japanese Patent Laid-Open No. 2005-60625).

(Method A2) is a method of converting a sulfonic acid ester group into a sulfonic acid group (—SO ₃ H) by hydrolysis. Specifically, the following methods are mentioned.
(1) A method of adding the polyarylene to an excess amount of water or alcohol containing a small amount of hydrochloric acid and stirring for 5 minutes or more,
(2) A method of reacting the polyarylene in trifluoroacetic acid at a temperature of about 80 to 120 ° C. for about 5 to 10 hours,
(3) A solution containing 1 to 9 moles of lithium bromide with respect to 1 mole of the sulfonic acid ester group (—SO ₃ R) in the polyarylene, for example, 80 to 80 of the polyarylene in a solution such as N-methylpyrrolidone. A method of adding hydrochloric acid after reacting at a temperature of about 150 ° C. for about 3 to 10 hours.

  (Method B2) is carried out by using a precursor having no sulfonic acid group or sulfonic acid ester group using a known sulfonating agent such as sulfuric anhydride, fuming sulfuric acid, chlorosulfonic acid, sulfuric acid, sodium hydrogen sulfite or the like under known conditions. [Polymer Preprints, Japan, Vol. 42, no. 3, p. 730 (1993); Polymer Preprints, Japan, Vol. 42, no. 3, p. 736 (1994); Polymer Preprints, Japan, Vol. 42, no. 7, p. 2490-2492 (1993)]. That is, as the reaction conditions for the sulfonation, a precursor polyarylene having no sulfonic acid group or sulfonic acid ester group is reacted with the sulfonating agent in the absence of a solvent or in the presence of a solvent. Examples of the solvent include hydrocarbon solvents such as n-hexane, ether solvents such as tetrahydrofuran and dioxane, aprotic polar solvents such as dimethylacetamide, dimethylformamide, and dimethylsulfoxide, tetrachloroethane, dichloroethane, chloroform, and chloride. And halogenated hydrocarbons such as methylene. The reaction temperature is not particularly limited, but is usually −50 to 200 ° C., preferably −10 to 100 ° C. Moreover, reaction time is 0.5 to 1,000 hours normally, Preferably it is 1 to 200 hours.

(Method C2) is a method in which the monomers shown in the above (Method C1) are mixed with the monomer represented by the general formula (2c), which can be the structural unit represented by the above general formula (2a), and the general formula (3a) ) Or -SM group (M represents a hydrogen atom or an alkali metal atom) by copolymerizing with a monomer or oligomer represented by the general formula (3d) that can be a structural unit represented by After obtaining the precursor polyarylene, it can be sulfonated by reacting the compound represented by the following general formula (5) or (6) under alkaline conditions.

In the general formula (5), R ⁴⁰ represents at least one atom or group selected from the group consisting of a hydrogen atom, a fluorine atom, an alkyl group, and a fluorine-substituted alkyl group, and g represents an integer of 1 to 20. Show.

In the general formula (6), L represents at least one atom selected from the group consisting of a chlorine atom, a bromine atom, and an iodine atom, and M represents a hydrogen atom or an alkali metal atom. R ⁴⁰ and g have the same meanings as ^{R 40} and g in the general formula (5).

[Proton conducting membrane]
The sulfonated polyarylene used in the present invention is composed of the above-mentioned copolymer, and is used in a membrane state when used in a solid polymer electrolyte for a fuel cell (hereinafter, the membrane state is referred to as a proton conducting membrane). .

  The proton conductive membrane used in the present invention can be produced by a casting method or the like in which the sulfonated polyarylene is mixed in an organic solvent and cast on a substrate to form a film. Here, the substrate is not particularly limited as long as it is a substrate used in an ordinary 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 sulfonated polyarylene may be a solvent that dissolves the copolymer or a solvent that swells. For example, 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, ethanol Alcohols such as propanol, iso-propyl alcohol, sec-butyl alcohol, tert-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoe 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, N-methyl-2-pyrrolidone (hereinafter referred to as “NMP”) is preferable from the viewpoint of solubility and solution viscosity.

  When a mixture of an aprotic polar solvent and another solvent is used as the solvent, the composition of the mixture is such that the aprotic polar solvent is 95 to 25% by mass, preferably 90 to 25% by mass, A solvent is 5-75 mass%, Preferably it is 10-75 mass% (however, total is 100 mass%). 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 sulfonated polyarylene and the additive are dissolved is usually 5 to 40% by mass, preferably 7 to 25% by mass, although it depends on the molecular weight of the sulfonated polyarylene. If it is less than 5% by mass, it is difficult to form a thick film, and pinholes are easily generated. On the other hand, if it exceeds 40% by mass, the solution viscosity is too high to form a film, and surface smoothness may be lacking.

  The solution viscosity is usually 2,000 to 100,000 mPa · s, preferably 3,000 to 50,000 mPa · s, although it depends on the molecular weight of the sulfonated polyarylene, the polymer concentration and the additive concentration. s. If it is less than 2,000 mPa · s, the retention of the solution during film formation is poor and it may flow from the substrate. On the other hand, if it exceeds 100,000 mPa · s, the viscosity is too high to be extruded from the die, and it may be difficult to form a film by the casting method.

  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 residual solvent amount of the resulting proton conducting membrane is reduced. be able to.

  In addition, after film formation, before immersing an undried film in water, you may predry an undried film. 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 mass or less. Further, depending on the immersion conditions, the amount of residual solvent in the obtained film can be set to 1% by mass or less. As such conditions, for example, the amount of water used is 50 parts by mass or more with respect to 1 part by mass 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. Next, the film can be obtained by vacuum drying at 50 to 150 ° C., preferably under reduced pressure of 500 mmHg to 0.1 mmHg for 0.5 to 24 hours.
The proton conductive 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, the polyarylene having the sulfonic acid ester group or the alkali metal salt of sulfonic acid is formed into a film by the method described above, and then subjected to an appropriate post-treatment such as hydrolysis or acid treatment in the present invention. The proton conducting membrane used can also be manufactured. Specifically, a polyarylene having a sulfonic acid ester group or an alkali metal salt of a sulfonic acid is formed into a film by the method described above, and then the membrane is hydrolyzed or acid-treated to thereby obtain a sulfonated polyarylene. A proton conducting membrane containing can be produced.

  In addition, when producing a proton conductive membrane, in addition to the sulfonated polyarylene, inorganic acids such as sulfuric acid and phosphoric acid, phosphoric acid glass, tungstic acid, phosphate hydrate, β-alumina proton substitution product, proton introduction Inorganic proton conductor particles such as oxides, organic acids including carboxylic acids, organic acids including sulfonic acids, organic acids including phosphonic acids, appropriate amounts of water, and the like may be used in combination.

[electrode]
The electrode used in the present invention comprises a catalyst metal particle or an electrode catalyst in which the catalyst metal particle is supported on a conductive carrier, an electrode electrolyte, and other components such as carbon fiber, a dispersant, and a water repellent as necessary. May be included.

  The catalyst metal particles are not particularly limited as long as they have catalytic activity, but metal black made of noble metal fine particles such as platinum black can be used.

  The conductive carrier for supporting the catalyst metal particles is not particularly limited as long as it has conductivity and appropriate corrosion resistance, but has a sufficient specific surface area for highly dispersing the catalyst metal particles and sufficient electron conduction. Therefore, it is desirable to use carbon (carbon) as a main component. The catalyst carrier that constitutes the electrode not only supports the catalyst metal particles, but also must function as a current collector for taking out electrons to the external circuit or taking them in from the external circuit. When the electric resistance of the catalyst carrier is high, the internal resistance of the battery is increased, and as a result, the performance of the battery is lowered. For this reason, the electronic conductivity of the catalyst carrier contained in the electrode must be sufficiently high. That is, it can be used as long as it has sufficient electronic conductivity as an electrode catalyst carrier, and preferably a carbon material with fine pores is used. As the carbon material having developed pores, carbon black, activated carbon or the like can be preferably used. Examples of carbon black include channel black, furnace black, thermal black, acetylene black, and the like. Activated carbon is obtained by carbonizing and activating various carbon-containing materials. It is also possible to include metal oxides, metal carbides, metal nitrides and polymer compounds having electronic conductivity. In addition, the main component said here means containing 60% or more of carbonaceous matter.

  In addition, platinum or a platinum alloy is used as the catalyst metal particles supported on the conductive carrier. However, when a platinum alloy is used, stability and activity as an electrode catalyst can be further imparted. Platinum alloys include platinum group metals other than platinum (ruthenium, rhodium, palladium, osmium, iridium), cobalt, iron, titanium, gold, silver, chromium, manganese, molybdenum, tungsten, aluminum, silicon, rhenium, zinc, And an alloy of platinum and one or more selected from the group consisting of tin and platinum, and the platinum alloy may contain an intermetallic compound of platinum and a metal to be alloyed.

  The supported rate of platinum or platinum alloy (ratio of the mass of platinum or platinum alloy to the total mass of the supported catalyst) is preferably 20 to 80% by mass, particularly preferably 30 to 55% by mass. Within this range, high output can be obtained. If the loading rate is less than 20% by mass, sufficient output may not be obtained. If the loading rate exceeds 80% by mass, platinum or platinum alloy particles may not be supported on the carbon material serving as a carrier with good dispersibility.

  Further, the primary particle diameter of platinum or platinum alloy is preferably 1 to 20 nm in order to obtain a highly active gas diffusion electrode. In particular, a large surface area of platinum or platinum alloy can be secured in terms of reaction activity. It is preferable that it is 2-5 nm.

As the electrode electrolyte, an ion conductive polymer electrolyte (ion conductive binder) having a sulfonic acid group is suitably used. Usually, the supported catalyst is covered with the electrolyte, and protons (H ⁺ ) move through a path where the electrolyte is connected.

  As the ion conductive polymer electrolyte having a sulfonic acid group, a perfluorocarbon polymer represented by Nafion, Flemion, and Aciplex is particularly preferably used. In addition to perfluorocarbon polymers, sulfonated products of vinyl monomers such as polystyrene sulfonic acid, polymers having sulfonic acid groups or phosphoric acid groups introduced into heat-resistant polymers such as polybenzimidazole and polyether ether ketone, An ion conductive polymer electrolyte mainly composed of an aromatic hydrocarbon compound such as sulfonated polyarylene described in the present specification may be used.

  Moreover, it is preferable to contain the said ion conductive binder in the ratio of 0.1-3.0 by mass ratio with respect to catalyst particles, and it is preferable to contain especially in the ratio of 0.3-2.0. If the ion conductive binder ratio is less than 0.1, protons cannot be transmitted to the electrolyte membrane, and sufficient output may not be obtained. If the ion conductive binder ratio exceeds 3.0, the ion conductive binder may not be obtained. May completely cover the catalyst particles, the gas cannot reach platinum, and there is a possibility that sufficient output cannot be obtained.

As carbon fibers that can be added as necessary, rayon-based carbon fibers, PAN-based carbon fibers, lignin poval-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, and the like can be used. Then, vapor growth carbon fiber is preferable. When carbon fiber is included, the pore volume in the electrode catalyst layer increases, so that the diffusibility of fuel gas and oxygen gas is improved, and flooding due to the generated water can be improved, and the power generation performance is improved. .
The carbon fiber may be contained in one or both of the anode-side and cathode-side electrode catalyst layers.

  Examples of the dispersant include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant. The said dispersing agent may be used individually by 1 type, or may be used in combination of 2 or more type. Among these, a surfactant having a basic group is preferable, an anionic or cationic surfactant is more preferable, and a surfactant having a molecular weight of 5,000 to 30,000 is more preferable. . When the above dispersant is added to the electrode paste composition used for forming the electrode catalyst layer, the storage stability and fluidity are excellent, and the productivity during coating is improved.

[Membrane-electrode structure]
The membrane-electrode structure of the present invention may consist only of an anode catalyst layer, a proton conducting membrane, and a cathode catalyst layer. However, both the anode and cathode are electrically conductive such as carbon paper or carbon cloth outside the catalyst layer. More preferably, a gas diffusion layer made of a porous porous substrate is disposed. Since the gas diffusion layer also functions as a current collector, in this specification, when the gas diffusion layer is provided, the gas diffusion layer and the catalyst layer are collectively referred to as an electrode.

  In the polymer electrolyte fuel cell having the membrane-electrode structure of the present invention, a gas containing oxygen is supplied to the cathode, and a gas containing hydrogen is supplied to the anode. Specifically, for example, a separator in which a groove to be a gas flow path is formed is disposed outside both electrodes of the membrane-electrode structure, and the gas is flowed through the gas flow path to thereby form the membrane-electrode structure. Supply fuel gas.

  As a method for producing the membrane-electrode structure of the present invention, a method of directly forming a catalyst layer on a proton conductive membrane and sandwiching it with a gas diffusion layer as necessary, a base material to be a gas diffusion layer such as carbon paper A method of forming a catalyst layer on the surface and bonding it to a proton conductive membrane, and forming a catalyst layer on a flat plate, transferring it to the proton conductive membrane, peeling the flat plate, and further, if necessary, a gas diffusion layer Various methods, such as a method of sandwiching with, can be adopted.

  As a method for forming the catalyst layer, a dispersion obtained by dispersing a supported catalyst and a perfluorocarbon polymer having a sulfonic acid group in a dispersion medium (if necessary, a water repellent, a pore-forming agent, a thickening agent) is used. And a known method of forming on an ion exchange membrane, a gas diffusion layer, or a flat plate.

Examples of the method for forming the electrode paste composition include brush coating, brush coating, bar coater coating, knife coater coating, doctor blade method, screen printing, and spray coating.
When the catalyst layer is not directly formed on the proton conductive membrane, the catalyst layer and the proton conductive membrane are preferably joined by a hot press method, an adhesion method (see JP-A-7-220741) or the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example. In Examples, “%” means “% by mass” unless otherwise specified.

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

[Molecular weight]
The copolymer obtained in each Example and Comparative Example described later is dissolved in an N-methylpyrrolidone buffer solution (hereinafter referred to as “NMP buffer solution”), and converted to polystyrene by gel permeation chromatography (GPC). The number average molecular weight (Mn) and the weight average molecular weight (Mw) were determined. The NMP buffer solution was prepared at a ratio of NMP (3 L) / phosphoric acid (3.3 mL) / lithium bromide (7.83 g).

[Equivalent of sulfonic acid group]
The obtained sulfonated polyarylene 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, dissolved in a mixed solvent of THF / water, titrated with a standard solution of NaOH using phenolphthalein as an indicator, and the equivalent of sulfonic acid groups (ion exchange capacity) from the neutral point. (Meq / g) was determined.

[Hot water test]
The proton conductive membrane 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), the proton conducting membrane was placed in a polycarbonate 250 ml bottle, about 100 ml of distilled water was added thereto, and a pressure cooker tester (HIRAYAMA MFS) was added. The product was heated at 120 ° C. for 24 hours using CORP, PC-242HS). After completion of the test, each film was taken out from the hot water, the surface water was gently wiped off with a Kimwipe, and the water content was weighed to determine the water content. Moreover, the dimension of the film was measured and the swelling rate was calculated | required. Furthermore, this membrane was conditioned at 24 ° C. and RH 50%, water was distilled off, the weight after the hot water test was weighed, and the weight residual ratio was determined.

[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. According to the following formula (1), the specific resistance of the membrane was calculated from the distance between the lines and the resistance gradient, and the proton conductivity was calculated from the reciprocal of the specific resistance.

[Heat resistance test]
A proton conducting membrane cut to 2 cm × 3 cm was sandwiched between bencots, placed in a crow sample tube, and heated in a compact precision thermostat (AWC-2) at 160 ° C. for 24 hours under air conditions. The heated proton conducting membrane was dissolved in NMP buffer solvent at a concentration of 0.2 wt%, and the molecular weight and area area (A24) were determined by GPC (NMP buffer solvent) (manufactured by Tosoh Corporation HCL-8220). The proton conducting membrane before heating was also measured under the same conditions, the molecular weight and area area (A0) were determined, and the insoluble fraction was determined according to the change in molecular weight and the following mathematical formula (2). The NMP buffer solvent was prepared at a ratio of NMP (3 L) / phosphoric acid (3.3 mL) / lithium bromide (7.83 g).

[Production of membrane-electrode structure]
Platinum particles were supported on carbon black (furnace black) having an average diameter of 50 nm at a mass ratio of carbon black: platinum = 1: 1 to prepare catalyst particles. Next, the catalyst particles are placed in a perfluoroalkylenesulfonic acid polymer compound solution (Nafion (trade name) manufactured by Dupont) as an ion conductive binder at a mass ratio of ion conductive binder: catalyst particles = 8: 5. A catalyst paste was prepared by uniformly dispersing.

By applying the catalyst paste on both sides of the proton conductive membranes made of the polymers obtained in Examples and Comparative Examples described later, applying a bar coater so that the platinum content is 0.5 mg / cm ² and drying, An electrode coating film (Catalyst Coated Membrane: CCM) was obtained. The drying was performed at 100 ° C. for 15 minutes, followed by secondary drying at 140 ° C. for 10 minutes.

  Carbon black and polytetrafluoroethylene (PTFE) particles are mixed at a mass ratio of carbon black: PTFE particles = 4: 6, and a slurry in which the obtained mixture is uniformly dispersed in ethylene glycol is mixed on one side of carbon paper. The base layer was coated and dried to prepare two gas diffusion layers composed of the base layer and carbon paper.

  The CCM was sandwiched between the gas diffusion layer and the base layer side, and hot pressing was performed to obtain a membrane-electrode structure. The hot pressing was performed at 160 ° C. and 3 MPa for 5 minutes. Further, the membrane-electrode structure obtained in this example can constitute a solid polymer fuel cell by further laminating a separator that also serves as a gas passage on the gas diffusion layer.

[Evaluation of power generation characteristics]
Using the obtained membrane-electrode structure, the power generation performance was evaluated under the power generation conditions where the temperature was 85 ° C., the relative humidity on the fuel electrode side / oxygen electrode side was 100% / 100%, and the current density was 1 A / cm ^2. did. Pure hydrogen was supplied to the fuel electrode side, and air was supplied to the oxygen electrode side. Furthermore, as an evaluation of power generation durability, a dry / wet cycle test was performed at a relative humidity of 100/100% RH to 0/0% RH under the conditions of a temperature of 85 ° C. and an OCV using the membrane-electrode structure. The time to leak was measured. If the time until cross leak is 5000 cycles or more, it is indicated as “◎” as excellent, and “3,000” or more and less than 5000 cycles is indicated as “good”, and if it is less than 3000 cycles Displayed as “×”.

<Structural unit having nitrogen-containing heterocycle>
As nitrogen-containing heterocycles, 2,5-dichloropyridine (manufactured by Tokyo Chemical Industry), 2,5-dibromopyrimidine (Chem. Lett., 583-586 (1992)), 5,5′-dibromo-2,2′- Bipyridine (Chem. Lett., 223 (1990)), 5,8-dibromoquinoline (Macromolecules, 24, 5883-5858 (1991)), 2,6-dichloroquinoline (Macromolecules, 27, 756-761 (1994)) 2,6-dichloro-1,5-naphthyridine, 2,2′-dichloro-6,6′-biquinoline (Macromolecules, 28, 4260-4267 (1995)), 5,8-quinoxaline, 2,6-quinoxaline ( J. Am. Chem. Soc., 118, 3930-3937 ( 996)) was used.

<Synthesis of a structural unit having a sulfonic acid group>
Chlorosulfonic acid (233.0 g, 2 mol) was added to a 3 L three-necked flask equipped with a stirrer and a condenser, followed by 2,5-dichlorobenzophenone (100.4 g, 400 mmol), and an oil bath at 100 ° C. For 8 hours. After a predetermined time, the reaction solution was slowly poured onto crushed ice (1000 g) and extracted with ethyl acetate. The organic layer was washed with brine and dried over magnesium sulfate, and then ethyl acetate was distilled off to obtain pale yellow crude crystals (3- (2,5-dichlorobenzoyl) benzenesulfonic acid chloride). The crude crystals were used in the next step without purification.

2,2-Dimethyl-1-propanol (neopentyl alcohol) (38.8 g, 440 mmol) was added to 300 ml of pyridine and cooled to about 10 ° C. The crude crystals obtained above were gradually added thereto over about 30 minutes. After the total amount was added, the reaction was further stirred for 30 minutes. After the reaction, the reaction solution was poured into 1000 ml of aqueous hydrochloric acid, and the precipitated solid was collected. The obtained solid was dissolved in ethyl acetate, washed with aqueous sodium hydrogen carbonate solution and brine, dried over magnesium sulfate, and then ethyl acetate was distilled off to obtain crude crystals. This was recrystallized with methanol to obtain white crystals of neopentyl 3- (2,5-dichlorobenzoyl) benzenesulfonate (30-1), which was the target product.

<Synthesis of a structural unit having an aromatic structure>
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, 2,2-bis (4- Hydroxyphenyl) -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 the formula (30-2).

Example 1
19.06 g (47.5 mmol) of the compound represented by the above formula (30-1), 0.25 g (1.7 mmol) of 2,5-dichloropyridine, and the compound represented by the above formula (30-2) 6.40 g (0.8 mmol), bis (triphenylphosphine) nickel dichloride 1.31 g (2.0 mmol), triphenylphosphine 3.93 g (15 mmol), sodium iodide 0.22 g (1.5 mmol), zinc 7 To a mixture of .84 g (120 mmol), 85 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 193 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid. Lithium bromide (13.27 g, 153 mmol) was added to the filtrate and 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 1.5 L of water and solidified. The coagulum was immersed in acetone, filtered and washed. The washed product was washed while being stirred with 370 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. It was confirmed that the obtained polymer was represented by the following formula (30-3).

(Examples 2-9)
A polymer was obtained in the same manner as in Example 1 except that a nitrogen-containing heterocycle as shown in Table 1 was used and the charge ratio was used at a ratio as shown in Table 1. The results of measuring the molecular weight of the obtained polymer by GPC and the ion exchange capacity are shown in Table 1.

(Comparative Example 1)
19.66 g (49.0 mmol) of the compound represented by the above formula (30-1), 8.20 g (1.0 mmol) of the compound represented by the above formula (30-2), bis (triphenylphosphine) nickel 92 mL of dried DMAc in a mixture of 1.31 g (2.0 mmol) dichloride, 3.93 g (15 mmol) triphenylphosphine, 0.22 g (1.5 mmol) sodium iodide, 7.84 g (120 mmol) zinc under nitrogen. added.

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 193 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid. To the filtrate, 12.77 g (147 mmol) of lithium bromide was added and 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 1.5 L of water and solidified. The coagulum was immersed in acetone, filtered and washed. The washed product was washed while being stirred with 370 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. The results of measuring the molecular weight of the obtained polymer by GPC and the ion exchange capacity are shown in Table 1. It was confirmed that the obtained polymer was represented by the following formula (30-4).

(Comparative Example 2)
19.26 g (48.0 mmol) of the compound represented by the above formula (30-1) and 0.35 g (1.1 mol) of the compound represented by (30-5) and (30-2) Compound 7.38 g (0.9 mmol), bis (triphenylphosphine) nickel dichloride 1.31 g (2.0 mmol), triphenylphosphine 3.93 g (15 mmol), sodium iodide 0.22 g (1.5 mmol), zinc 89 mL of dry DMAc in 7.84 g (120 mmol) of the mixture 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 193 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid. Lithium bromide (13.08 g, 150.6 mmol) was added to the filtrate and 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 1.5 L of water and solidified. The coagulum was immersed in acetone, filtered and washed. The washed product was washed while being stirred with 370 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. The results of measuring the molecular weight of the obtained polymer by GPC and the ion exchange capacity are shown in Table 1. It was confirmed that the obtained polymer was represented by the following formula (30-6).

  It was found that by introducing a heterocyclic ring containing nitrogen in the main chain, the proton conductivity is equivalent to that of Comparative Example 1, and the moisture content and area change in the hot water test can be suppressed. Further, it was found that the cross-linking resistance in the heat resistance test was higher when a heterocycle containing nitrogen was introduced, and the membrane-electrode structure of this example also had higher power generation durability.

  Further, when comparing Examples 1 to 9 and Comparative Example 2, it is preferable to introduce a heterocyclic ring containing nitrogen into the main chain, rather than introducing a heterocyclic ring containing nitrogen into the side chain, It was found that the area change can be suppressed and the power generation durability of the membrane-electrode structure is improved.

Claims (1)

In a membrane-electrode structure for a polymer electrolyte fuel cell in which an anode electrode is provided on one side of a proton conducting membrane and a cathode electrode is provided on the other side,
The proton conductive membrane includes a structural unit having a proton conductive group represented by the following general formula (1a), and a structural unit having a heterocyclic structure containing nitrogen represented by the following general formula (2a) in the main chain. And a sulfonated polyarylene containing a structural unit having an aromatic structure represented by the following general formula (3a) : A membrane-electrode structure for a polymer electrolyte fuel cell, comprising:

Wherein (1a), Y represents a -CO-, Z is a direct bond, _{or, - (CH 2) l -} (l is an integer of 1 to _{10), - C (CH 3)} 2 -, - O-, and represents at least one structure selected from the group consisting of -S-, Ar represents a benzene ring having a substituent represented by _-SO 3 H. m is an 0, n represents a 0, k is an integer of 1-4. Among the single lines at the end of the structural unit, those not having a substituent displayed on one side mean connection with the adjacent structural unit. ]

[In the formula (2a), Ar ³¹ represents any one of pyridine, pyrimidine, quinoline, naphthyridine, quinoxaline, or a structure represented by the following chemical formula (2b) . Among the single lines at the end of the structural unit, those not having a substituent displayed on one side mean connection with the adjacent structural unit. ]

[In the formula (2b), among the single wires at the end of the structural unit, one on which no substituent is displayed means connection with an adjacent structural unit. ]

[In the formula (3a), A represents —C (CF ₃ ) ₂ —, and D independently represents a direct bond, or —CO—, —SO ₂ —, —SO—, — (CF ₂ ) ₁ — (l is an integer of 1 to _{10), - C (CF 3)} 2 -, - (CH 2) l - (l is an integer of 1 to _{10), - CR '2 - (} R' is an aliphatic An aromatic hydrocarbon group, an aromatic hydrocarbon group, or a halogenated hydrocarbon group), -O-, -S-, a cyclohexylidene group, and a fluorenylidene group. , B are all oxygen atoms, and R ^{1 to} R ⁴ may be the same as or different from each other, and may be a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group in which part or all are halogenated, allyl Selected from the group consisting of a group, an aryl group, a nitro group, and a nitrile group It represents at least one kind of atom or group, any one of R ^{5 to} R ⁸ represents a nitrile group, the remaining three represent a hydrogen atom, and R ^{9 to} R ¹⁶ all represent a hydrogen atom. s represents 0, t represents 1, and r represents an integer of 1 or more. Among the single lines at the end of the structural unit, those not having a substituent displayed on one side mean connection with the adjacent structural unit. ]