JP2019182954A - Polyelectrolyte, method for producing the same, polyelectrolyte film including the same, catalyst layer, film/electrode binding body, and fuel cell - Google Patents

Abstract

To provide a polyelectrolyte having high proton conductivity and high oxidation degradation resistance, and having excellent productivity and film moldability, a method for producing the same, a film, a catalyst layer, a film/electrode binding body and a fuel cell.SOLUTION: A polyelectrolyte has hydrophobic segments represented by formula (1)/formula (1) and formula (2), and hydrophilic segments comprising an aromatic ring having a sulfonic acid group, which are directly carbon-carbon bonded (y is 1-1500, z is 0-1500, y:z is 100: 0-10:90. R-Rare preferably H).SELECTED DRAWING: None

Description

  The present invention relates to a polymer electrolyte suitable for a solid polymer fuel cell, a production method thereof, a polymer electrolyte membrane using the same, a fuel cell catalyst layer, a fuel cell membrane / electrode assembly, and a fuel cell It is.

  In recent years, development of highly efficient and clean energy sources has been demanded from the viewpoint of environmental problems such as global warming. Fuel cells are attracting attention as one candidate for that requirement. A fuel cell directly supplies power by supplying a fuel such as hydrogen gas or methanol and an oxidant such as oxygen to electrodes separated by an electrolyte, while oxidizing the fuel on the one hand and reducing the oxidant on the other. is there. Among the fuel cell materials described above, one of the most important materials is an electrolyte. Various types of electrolyte membranes have been developed so far to separate the electrolyte fuel and oxidant, and in recent years, the electrolyte membrane is composed of a polymer compound containing a proton conductive functional group such as a sulfonic acid group. The development of polymer electrolytes is thriving. In addition to the solid polymer fuel cell, such a polymer electrolyte is used as a raw material for electrochemical elements such as a humidity sensor, a gas sensor, and an electrochromic display element. Among these polymer electrolyte utilization methods, in particular, polymer electrolyte fuel cells are expected as one of the pillars of new energy technology. For example, a polymer electrolyte fuel cell using an electrolyte membrane made of a polymer compound having a proton-conducting functional group has features such as operation at a low temperature and reduction in size and weight. It has already been put to practical use in applications such as cogeneration systems for automobiles, and its application to consumer small portable devices is also being studied.

  As an electrolyte membrane used in a polymer electrolyte fuel cell, there is a styrene-based cation exchange membrane developed in the 1950s. However, the fuel cell has poor stability under a fuel cell operating environment and has a sufficient lifetime. Has not yet been manufactured. On the other hand, as an electrolyte membrane having practical stability, a perfluorocarbon sulfonic acid membrane represented by Nafion (registered trademark) has been widely studied. Perfluorocarbon sulfonic acid membranes are said to have high proton conductivity and excellent chemical stability such as acid resistance and oxidation resistance. However, Nafion (registered trademark) has a problem that it is very expensive because it uses high raw materials and undergoes complicated manufacturing processes. In addition, it has been pointed out that it is deteriorated by hydrogen peroxide generated by the electrode reaction and by-product hydroxy radical. Furthermore, due to its structure, there is a limit to the introduction of sulfonic acid groups that are proton conducting groups.

  Against this background, the development of hydrocarbon electrolyte membranes has come to be expected. The reason for this is that the hydrocarbon electrolyte membrane is easy to have a variety of chemical structures, the range of introduction of proton conducting groups such as sulfonic acid groups can be adjusted widely, compounding with other materials, introduction of crosslinking, etc. This is because there is a feature that is relatively easy.

  In recent years, as such a hydrocarbon-based polymer electrolyte membrane, many copolymers having a hydrophilic segment having a sulfonic acid group and a hydrophobic segment having substantially no sulfonic acid group have been reported. In such a polymer electrolyte membrane, the hydrophilic segment and the hydrophobic segment are phase-separated, and the portion where the hydrophilic segment is aggregated at a high concentration forms a proton conduction path, and the hydrophobic segment has a high concentration. It is a part that aggregates in the film and plays a role of ensuring the mechanical strength of the film.

  As a method for producing such a polymer electrolyte, a unit having a nucleophilic functional group such as a hydroxyl group or a sulfide group and a unit having a leaving substituent such as a halogen are prepared in advance, and the nucleophilic substitution reaction thereof is performed. (Patent Documents 1 and 2). Although this manufacturing method is simple, since an ether bond or a thioether bond is generated in the resin skeleton, there is a problem that it is easily oxidized and deteriorated when used as an electrolyte membrane for a fuel cell (Non-patent Document 1).

  In order to solve this problem, attempts have been made to connect a hydrophilic segment and a hydrophobic segment with a carbon-carbon direct bond to eliminate an ether bond or a thioether bond from the vicinity of the sulfonic acid group (Patent Documents 3 and 4). , 5). However, the polymer electrolyte obtained by this method still uses a skeleton having units such as polyethersulfone and polyetherketone in the hydrophobic segment, and the oxidation resistance of the electrolyte membrane under fuel cell operating conditions is still used. Although the performance is improved, when the Fenton test using hydrogen peroxide and divalent iron ions, which is a general test method for oxidation resistance, significant weight reduction and mechanical property deterioration are observed. It was not enough to say that it was sufficient.

  Polyphenylene-type polymer electrolytes in which hetero bonds such as ether bonds and thioether bonds are completely excluded from the main chain structure of the hydrophilic segment and the hydrophobic segment and are connected by a direct carbon-carbon bond are also being studied. For example, Patent Document 6 describes a polyphenylene type polymer electrolyte in which a hydrophilic monomer and a hydrophobic monomer are randomly connected by a carbon-carbon direct bond. However, in the present invention, the objective is to precisely control the microphase separation structure for imparting proton conductivity, gas permeability, and heat resistance. It is connected to the aromatic ring with a linking group containing a sex group, and its production process is complicated.

  In view of such circumstances, the present inventor has a hydrophilic segment in which a sulfonic acid group is introduced and the main chain is an aromatic ring, and a hydrophobic segment that has no sulfonic acid group and the main chain is an aromatic ring. There has been proposed a polymer electrolyte in which aromatic ring carbon-carbon direct bonds are connected, and further, hydrophobic segment aromatic rings are also connected by carbon-carbon direct bonds (Patent Document 7).

Japanese Patent Laid-Open No. 10-21944 JP 2005-126684 A JP 2007-177197 A JP 2008-88420 A JP2012-229418A JP2013-191375A JP 2017-179345 A

“Polymer”, March 2009, Vol. 50, No. 7, p. 1671-1681

  The polymer electrolyte described in Patent Document 7 includes a segment in which aromatic rings composed of two or more phenylene units composed of a paraphenylene unit, a metaphenylene unit, and an orthophenylene unit are connected by a carbon-carbon bond as a hydrophobic segment. Used, the hydrophobic segment and the hydrophilic segment are also connected by a carbon-carbon bond, and the aromatic main chain skeleton does not include a hetero bond, so that the chemical durability is extremely high. However, Patent Document 7 does not specifically describe the ratio of the paraphenylene unit, the metaphenylene unit, and the orthophenylene unit constituting the hydrophobic segment, and it is not clear about the optimum structure as the polymer electrolyte membrane. It was. In addition, the polymer electrolyte specifically exemplified in the examples exhibits very high chemical durability and good solubility in a solvent, and a flexible membrane can be obtained. Since the production is complicated, a simpler production method of a polymer electrolyte in which the main chain is bonded only by an aromatic carbon-carbon bond has been desired.

  The present invention can be used as a polymer electrolyte membrane that exhibits high proton conductivity, has high resistance to oxidative degradation even under the operating conditions of a fuel cell, is easy to manufacture, and has good solubility in a solvent. Provided are a polymer electrolyte excellent in moldability such as a membrane, a production method thereof, a polymer electrolyte membrane using the same, a fuel cell catalyst layer, a fuel cell membrane / electrode assembly, and a fuel cell.

（前記一般式（１）及び（２）中、ｙは１〜１５００の整数、ｚは０〜１５００の整数を表し、ｙ：ｚは１００：０〜１０：９０の範囲にある。Ｒ¹〜Ｒ⁸は、それぞれ独立に、水素、フッ素、アルキル基、パーフルオロアルキル基、アリール基、アラルキル基、またはシアノ基を表す。） The present invention is a polyelectrolyte comprising a hydrophobic segment and a hydrophilic segment having a sulfonic acid group and a main chain mainly composed of an aromatic ring, wherein the hydrophobic segment has the following general formula It consists of a segment represented by (1), a segment represented by the following general formula (1) and a segment represented by the following general formula (2) arranged randomly, each of which is an aromatic ring The present invention relates to a polymer electrolyte characterized by being connected by a carbon-carbon direct bond.

(In the general formulas (1) and (2), y represents an integer of 1 to 1500, z represents an integer of 0 to 1500, and y: z is in the range of 100: 0 to 10:90. R ¹ to R ⁸ each independently represents hydrogen, fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, or a cyano group.)

（前記一般式（５）、一般式（６）及び式群（７）中、Ｈａｌは、塩素、臭素、またはヨウ素、Ｒ¹〜Ｒ⁸は、それぞれ独立に、水素、フッ素、アルキル基、パーフルオロアルキル基、アリール基、アラルキル基、またはシアノ基を表す。ｍは１〜４の整数、ｋ及びｌはそれぞれ０〜４の整数を表し、かつｋ＋ｌは１以上の整数である。ｐは０〜１０の整数、ｑは０〜１０の整数、ｒは１〜４の整数を表す。Ｘは、−ＣＯ−、−ＳＯ₂−、及び−Ｃ（ＣＦ₃）₂−からなる群より選ばれた少なくとも１種の構造を表し、Ｙは、−ＣＯ−、−ＳＯ₂−、−ＳＯ−、−ＣＯＮＨ−、−ＣＯＯ−、−（ＣＦ₂）_t−（ｔは１〜１０の整数）、−Ｃ（ＣＦ₃）₂−からなる群より選ばれた少なくとも１種の構造を表し、Ｚは直接結合又は、−（ＣＨ₂）_o−（ｏは１〜１０の整数）、−Ｃ（ＣＨ₃）₂−、−Ｏ−、及び−Ｓ−からなる群より選ばれた少なくとも１種の構造を表す。Ａｒ¹は、−ＳＯ₃Ｈ又は−Ｏ（ＣＨ₂）_sＳＯ₃Ｈ（ｓは１〜１２の整数）で表される置換基を有する芳香族基を表す。Ｍは水素、アルカリ金属、炭素数１〜１２のアルキル基、炭素数５〜１２のシクロアルキル基、炭素数６〜１８のアリール基、または炭素数７〜２０のアラルキル基を表す。） Moreover, this invention is a manufacturing method of said polymer electrolyte, Comprising: The compound represented by following General formula (5), the compound represented by following General formula (6), and following formula group (7) The present invention relates to a method for producing a polymer electrolyte, wherein one or more compounds selected from the group of compounds represented are copolymerized in the presence of a transition metal compound.

(In the general formula (5), the general formula (6) and the formula group (7), Hal is chlorine, bromine or iodine, and R ^{1 to} R ⁸ are each independently hydrogen, fluorine, alkyl group, A fluoroalkyl group, an aryl group, an aralkyl group, or a cyano group, m is an integer of 1 to 4, k and l are each an integer of 0 to 4, and k + 1 is an integer of 1 or more, and p is 0. Is an integer of 0 to 10, q is an integer of 0 to 10, and r is an integer of 1 to 4. X is selected from the group consisting of —CO—, —SO ₂ —, and —C (CF ₃ ) ₂ —. represents at least one structure, Y _{is, -CO -, - SO 2 -} , - SO -, - CONH -, - COO -, - (CF 2) t - (t is an integer of from 1 to 10), -C (CF _{3) 2} - represents at least one structure selected from the group consisting of, Z is a direct bond or, - (CH _{2 o} - (o is an integer of from 1 to _{10), - C (CH 3)} 2 -, - O-, and .Ar ¹ representing at least one structure selected from the group consisting of -S- are, -SO ₃ H or an aromatic group having a substituent represented by —O (CH ₂ ) _s SO ₃ H (s is an integer of 1 to 12), M is hydrogen, alkali metal, alkyl having 1 to 12 carbons. Group, a C5-C12 cycloalkyl group, a C6-C18 aryl group, or a C7-C20 aralkyl group.)

  The present invention also relates to a polymer electrolyte membrane for fuel cells using the polymer electrolyte of the present invention.

  The present invention also relates to a fuel cell catalyst layer using the polymer electrolyte of the present invention.

  The present invention also relates to a membrane / electrode assembly for a fuel cell using the polymer electrolyte of the present invention.

  The present invention also relates to a fuel cell using the polymer electrolyte of the present invention.

  The polymer electrolyte of the present invention can be used as a polymer electrolyte membrane that exhibits high proton conductivity and is highly resistant to oxidative degradation even under fuel cell operating conditions, and is manufactured from readily available raw materials using simple reactions. Since it has a high solubility in a solvent, it can be easily formed into a film.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have a hydrophobic segment represented by the following general formula (1) (hereinafter also referred to as metaphenylene segment), and the following general formula (2). A polymer segment comprising a hydrophobic segment (hereinafter also referred to as a paraphenylene segment) and a hydrophilic segment having a sulfonic acid group and a main chain mainly composed of an aromatic ring, All of these segments are linked by a carbon-carbon direct bond of an aromatic ring, the ratio of the metaphenylene segment to the paraphenylene segment is in a certain range, and the polyelectrolyte in which the arrangement is random is good for the solvent. It exhibits excellent solubility, high film-forming properties, and the obtained polymer electrolyte membrane has high proton conductivity and excellent chemical durability. Found that, it has led to the completion of the present invention. The polymer electrolyte of the present invention can be easily produced using readily available raw materials.

In the general formulas (1) and (2), y represents an integer of 1 to 1500, z represents an integer of 0 to 1500, and y: z is in the range of 100: 0 to 10:90. R ^{1 to} R ⁸ each independently represents hydrogen, fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, or a cyano group.

  One or more preferred embodiments of the present invention are polymer electrolytes in which y: z is 100: 0 to 50:50 in the general formulas (1) and (2). One or more preferred embodiments of the present invention are polymer electrolytes in which y: z is 80:20 to 50:50 in the general formulas (1) and (2).

  In one or more preferred embodiments of the present invention, the hydrophilic segment having a sulfonic acid group and the main chain mainly consisting of an aromatic ring is selected from the structural group represented by the following formula group (3). This is a polymer electrolyte having the structure:

In the formula group (3), m represents an integer of 1 to 4, k and l each represents an integer of 0 to 4, and k + 1 represents an integer of 1 or more. p represents an integer of 0 to 10, q represents an integer of 0 to 10, and r represents an integer of 1 to 4. X represents at least one structure selected from the group consisting of —CO—, —SO ₂ —, and C (CF ₃ ) ₂ —, and Y represents —CO—, —SO ₂ —, —SO—. , -CONH -, - COO -, - (CF 2) t - (t is an integer of from 1 to 10), and -C (CF _{3) 2} - represents at least one structure selected from the group consisting of, Z is a direct bond or at least one selected from the group consisting of — (CH ₂ ) _o — (o is an integer of 1 to 10), —C (CH ₃ ) ₂ —, —O—, and —S—. Represents the structure of Ar ¹ represents an aromatic group having a substituent represented by —SO ₃ H or —O (CH ₂ ) _s SO ₃ H (s is an integer of 1 to 12).

  One or more more preferable embodiments of the present invention are polymer electrolytes having a structure represented by the following general formula (4).

  In the general formula (4), x represents an integer of 1 to 2000, y represents an integer of 1 to 1500, and z represents an integer of 0 to 1500, and y: z is in the range of 100: 0 to 10:90. .

  Reference will now be made in detail to one or more embodiments of the invention. In addition, this invention is not limited to the following embodiment.

  In one or more embodiments, the present invention includes a hydrophilic segment having a hydrophobic segment (metaphenylene segment) represented by the following general formula (1) and a sulfonic acid group, and a main chain mainly composed of an aromatic ring. And each of the segments relates to a polyelectrolyte in which all segments are connected by a carbon-carbon direct bond of an aromatic ring. Alternatively, in one or more embodiments of the present invention, a hydrophobic segment (metaphenylene segment) represented by the following general formula (1), a hydrophobic segment (paraphenylene segment) represented by the following general formula (2) And a hydrophilic segment having a sulfonic acid group, the main chain mainly consisting of an aromatic ring, each segment being all connected by a carbon-carbon direct bond of an aromatic ring, and a metaphenylene segment and a paraphenylene The present invention relates to a polymer electrolyte in which the ratio of segments is in a certain range and the arrangement of metaphenylene segments and paraphenylene segments is random.

前記一般式（１）及び（２）中、ｙは１〜１５００の整数、ｚは０〜１５００の整数を表し、ｙ：ｚは１００：０〜１０：９０の範囲にある。Ｒ¹〜Ｒ⁸は、それぞれ独立に、水素、フッ素、アルキル基、パーフルオロアルキル基、アリール基、アラルキル基、またはシアノ基を表す。

In the general formulas (1) and (2), y represents an integer of 1 to 1500, z represents an integer of 0 to 1500, and y: z is in the range of 100: 0 to 10:90. R ^{1 to} R ⁸ each independently represents hydrogen, fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, or a cyano group.

  In the polyelectrolyte, the aromatic ring constituting the main chain of the hydrophobic segment is linked by a carbon-carbon direct bond, does not include a hetero bond such as an ether bond or a thioether bond, and the hydrophobic segment and the hydrophilic segment are also included. Since it is connected by a carbon-carbon direct bond of an aromatic ring, it exhibits high durability against severe oxidation conditions under fuel cell operation.

The substituents R ^{1 to} R ⁸ on the aromatic ring in the general formulas (1) and (2) are each independently hydrogen, fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, or a cyano group. is there. From the viewpoint of availability, it is preferable that R ^{1 to} R ⁸ are all hydrogen.

  The number of repeating units y of metaphenylene in the general formula (1) is an integer of 1 to 1500, preferably an integer of 5 to 500, and more preferably an integer of 6 to 250. Moreover, the repeating unit number z of paraphenylene in General formula (2) is an integer of 0-1500, Preferably, it is an integer of 5-500, More preferably, it is an integer of 6-250. If y or z exceeds 1500, the polymer electrolyte is difficult to dissolve and molding becomes difficult.

  The ratio of the number of repeating units y of metaphenylene and the number of repeating units z of paraphenylene is in the range of 100: 0 to 10:90. Within this range, the polymer electrolyte exhibits good solubility and can be easily formed into a film. When the ratio of y and z is not in this range, that is, in the range of y: z = 10: 90 to 0: 100, and most of them have a paraphenylene structure, the resulting polymer electrolyte is hardly soluble in the solvent, It becomes difficult to form a film.

  As a ratio (y: z) of a metaphenylene segment and a paraphenylene segment, y: z is more preferably 100: 0 to 50:50 in terms of better solubility in a solvent. Further, y: z is more preferably 80:20 to 50:50 in that the solubility is good and a polymer electrolyte having a high molecular weight is obtained.

  The arrangement of the metaphenylene segment and the paraphenylene segment is random. Random means that the arrangement of metaphenylene and paraphenylene monomers is not ordered.

  The hydrophilic segment having a sulfonic acid group constituting the polymer electrolyte of the present invention and having a main chain mainly composed of an aromatic ring (hereinafter also referred to as a sulfonic acid group-containing segment) has a sulfonic acid group and a main chain. Is mainly composed of an aromatic ring, and a sulfonic acid group is directly bonded to the aromatic ring. Since the segment has a sulfonic acid group, the proton conductivity of the polymer electrolyte is expressed, and the main chain is mainly composed of an aromatic ring, so that the heat resistance and chemical durability are excellent.

  Examples of the sulfonic acid group in the present invention include a sulfonic acid group, a salt of a sulfonic acid group, and a sulfonic acid ester group. That is, the sulfonic acid group may be a salt such as sodium or potassium, or may be protected with an ester group such as neopentyl ester, methyl ester or propyl ester. In particular, during and after the synthesis of the sulfonic acid group-containing segment precursor, it is often preferred that the polymer electrolyte is in a state having a protective group such as a salt or an ester. In many cases, it is converted into a sulfonic acid group by being immersed in an aqueous solution of an inorganic acid. Therefore, in the present invention, the sulfonic acid group includes a group having a protective group such as a salt or an ester as long as it is a group that easily becomes a sulfonic acid group.

  The amount of the sulfonic acid group is preferably 1 to 6 and more preferably 1 to 4 per repeating unit forming the hydrophilic sulfonic acid group-containing segment. When the amount of the sulfonic acid group is larger than 6, the water solubility of the segment increases, and the handling during synthesis tends to be difficult. If it is less than one, sufficient proton conductivity tends to be difficult to develop.

  The sulfonic acid group-containing segment in the present invention has a main chain mainly composed of an aromatic ring. Here, “consisting mainly of an aromatic ring” means that the molecular weight of the portion other than the linking group (ether group, thioether group, sulfone group, ketone group, sulfide group, etc.) of the main chain in the sulfonic acid group-containing segment is 100%. In this case, it means that 70% or more of them are composed of aromatic rings. Examples of aromatic rings include benzene, naphthalene, anthracene, biphenyl, aromatic heterocycles containing sulfur, nitrogen and the like. When the main chain is mainly composed of an aromatic ring, chemical and thermal stability is high. Examples of such a main chain structure include polyether, polyether ketone, polyether ether ketone, polyether sulfone, polyether ether sulfone, polyketone, polysulfone, polysulfide, polyphenylene, polyimide, polybenzimidazole, and the like.

  The sulfonic acid group-containing segment preferably has one or more structures selected from the structure group represented by the following formula group (3).

In the formula group (3), m represents an integer of 1 to 4, k and l each represents an integer of 0 to 4, and k + 1 represents an integer of 1 or more. p represents an integer of 0 to 10, q represents an integer of 0 to 10, and r represents an integer of 1 to 4. X represents at least one structure selected from the group consisting of —CO—, —SO ₂ —, and C (CF ₃ ) ₂ —, and Y represents —CO—, —SO ₂ —, —SO—. , -CONH -, - COO -, - (CF 2) t - (t is an integer of from 1 to 10), and -C (CF _{3) 2} - represents at least one structure selected from the group consisting of, Z is a direct bond or at least one selected from the group consisting of — (CH ₂ ) _o — (o is an integer of 1 to 10), —C (CH ₃ ) ₂ —, —O—, and —S—. Represents the structure of Ar ¹ represents an aromatic group having a substituent represented by —SO ₃ H or —O (CH ₂ ) _s SO ₃ H (s is an integer of 1 to 12).

  Specific examples of the structure of the sulfonic acid group-containing segment represented by the formula group (3) include the structure represented by the following formula group (8).

  Next, the manufacturing method of the polymer electrolyte of this invention is demonstrated. The production method of the polymer electrolyte of the present invention is not particularly limited, but a method of linking a precursor of a sulfonic acid group-containing segment and a precursor of a metaphenylene segment represented by the general formula (1), or sulfone A method of connecting the precursor of the acid group-containing segment, the precursor of the metaphenylene segment represented by the general formula (1), and the precursor of the paraphenylene segment represented by the general formula (2) is preferably used. Here, the precursor becomes a sulfonic acid group-containing segment, a metaphenylene segment represented by the general formula (1), and a paraphenylene segment represented by the general formula (2), respectively, by a copolymerization reaction described later. Means a repeating unit having a reactive site. In the present invention, since the sulfonic acid group-containing segment and the metaphenylene segment, or the sulfonic acid group-containing segment, the metaphenylene segment, and the paraphenylene segment are connected by a direct bond of an aromatic ring, the precursor of each segment Needs to have a functional group for connecting the aromatic rings with a direct bond.

  For example, the compound represented by the following general formula (5) as a precursor of the metaphenylene segment represented by the general formula (1), and the following general formula as a precursor of the paraphenylene segment represented by the general formula (2) The compound represented by (6), one or more compounds selected from the group of compounds represented by the following formula group (7) as a precursor of the sulfonic acid group-containing segment, a Ullmann coupling reaction using metallic copper, According to the method described in Patent Document 5, the coupling can be performed using a method of coupling with a transition metal compound.

In general formula (5), general formula (6), and formula group (7), Hal is chlorine, bromine, or iodine, and R ^{1 to} R ⁸ are each independently hydrogen, fluorine, an alkyl group, or perfluoroalkyl. Represents a group, an aryl group, an aralkyl group, or a cyano group. m represents an integer of 1 to 4, k and l each represents an integer of 0 to 4, and k + 1 represents an integer of 1 or more. p represents an integer of 0 to 10, q represents an integer of 0 to 10, and r represents an integer of 1 to 4. X represents at least one structure selected from the group consisting of —CO—, —SO ₂ —, and —C (CF ₃ ) ₂ —, and Y represents —CO—, —SO ₂ —, —SO. -, - CONH -, - COO -, - (CF 2) t - (t is an integer of from 1 to _{10), - C (CF 3)} 2 - represents at least one structure selected from the group consisting of, Z is a direct bond or at least one selected from the group consisting of — (CH ₂ ) _o — (o is an integer of 1 to 10), —C (CH ₃ ) ₂ —, —O—, and —S—. Represents the structure of Ar ¹ represents an aromatic group having a substituent represented by —SO ₃ H or —O (CH ₂ ) _s SO ₃ H (s is an integer of 1 to 12). M represents hydrogen, an alkali metal, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms.

  Specific examples of the compound represented by the general formula (5) include 1,3-dichlorobenzene, 1,3-dibromobenzene, 1,3-diiodobenzene, 2,6-dichlorotoluene, 2,6- Dibromotoluene, 2,6-diiodotoluene, 2,6-dichloro-1,4-dimethylbenzene, 2,6-dibromo-1,4-dimethylbenzene, 2,6-diiodo-1,4-dimethylbenzene, 2,6-dichloro-1,3-dimethylbenzene, 2,6-dibromo-1,3-dimethylbenzene, 2,6-diiodo-1,3-dimethylbenzene, 2,6-dichlorobenzonitrile, 2,4 -Dichlorobenzonitrile, 2,6-dichlorofluorobenzene, 3,5-dichlorofluorobenzene and the like. One of these may be used alone, or two or more of these may be used in combination. Among these, at least one selected from the group consisting of 1,3-dichlorobenzene, 2,6-dichlorotoluene, and 2,6-dichlorobenzonitrile is preferable and inexpensive because it is easily available. 1,3-dichlorobenzene is more preferable.

  Specific examples of the compound represented by the general formula (6) include 1,4-dichlorobenzene, 1,4-dibromobenzene, 1,4-diiodobenzene, 2,5-dichlorotoluene, 2,5- Dibromotoluene, 2,5-diiodotoluene, 2,5-dichloro-1,4-dimethylbenzene, 2,5-dibromo-1,4-dimethylbenzene, 2,5-diiodo-1,4-dimethylbenzene, 2,5-dichloro-1,3-dimethylbenzene, 2,5-dibromo-1,3-dimethylbenzene, 2,5-diiodo-1,3-dimethylbenzene, 2,5-dichlorobenzonitrile, and 2, 5-dichlorofluorobenzene and the like can be mentioned. One of these may be used alone, or two or more of these may be used in combination. Of these, 1,4-dichlorobenzene, 2,5-dichlorotoluene, and 2,5-dichlorobenzonitrile are preferable because they are easily available, and 1,4-dichlorobenzene is more preferable because they are inexpensive. preferable.

  Specific examples of the compound represented by the formula group (7) include compounds represented by the following formula group (9).

  In the compound group represented by the formula group (9), a compound in which a chlorine atom is replaced with bromine or iodine can also be suitably used. Moreover, as M, as demonstrated in the said formula group (7), hydrogen, an alkali metal, a C1-C12 alkyl group, a C5-C12 cycloalkyl group, a C6-C18 aryl group Or represents a carbon number of 7 to 20, and is appropriately selected according to the polymerization conditions.

  The precursor of the sulfonic acid group-containing segment can be produced by reacting a corresponding aromatic compound with a sulfonated agent. A well-known thing can be used as a sulfonating agent, For example, it is sulfuric acid, anhydrous sulfuric acid, chlorosulfonic acid, acetyl sulfuric acid, fuming sulfuric acid, etc. Chlorosulfonic acid and / or fuming sulfuric acid is preferred because it has moderate reactivity. In the sulfonation reaction, a solvent may or may not be used. In the case of using a solvent, the solvent is not particularly limited as long as it is inert with respect to the sulfonated agent, and examples thereof include hydrocarbon solvents and halogenated hydrocarbons. Examples of the hydrocarbon solvent include saturated aliphatic hydrocarbons, and linear or branched hydrocarbons having 5 to 15 carbon atoms are particularly preferable. From the viewpoint of solubility, pentane, hexane, heptane, octane, and decane are preferable. Is more preferable. Examples of halogenated hydrocarbons include halogenated saturated aliphatic hydrocarbons and halogenated aromatic hydrocarbons. Examples of the halogenated saturated aliphatic hydrocarbon include monochloromethane, dichloromethane, trichloromethane, tetrachloromethane, monochloroethane, dichloroethane, trichloroethane, tetrachloroethane, and the like. Dichloromethane is preferable because of easy handling. Examples of the halogenated aromatic hydrocarbon include chlorobenzene, dichlorobenzene, trichlorobenzene, and the like, and chlorobenzene is preferable because of easy handling.

  The reaction temperature of the sulfonation process may be set as appropriate according to the reaction, specifically, it may be set to −80 ° C. to 200 ° C. which is the optimum use range of the sulfonation agent, more preferably −50 ° C. to 150 ° C, more preferably -20 ° C to 130 ° C. If the temperature is lower than −80 ° C., the reaction is slow, and the intended sulfonation tends not to proceed to 100%, and if the temperature is higher than 200 ° C., side reaction tends to occur. The reaction time of the sulfonating step can be appropriately selected depending on the structure of the aromatic compound used as a raw material, but it may usually be in the range of about 1 minute to 50 hours. When it is shorter than 1 minute, uniform sulfonation tends not to proceed, and when it is longer than 50 hours, side reaction tends to occur.

  The addition amount of the sulfonating agent in the sulfonating step is preferably 1 equivalent to 50 equivalents when the total amount of the sulfonated sites contained in the starting aromatic compound is defined as 1 equivalent. If the amount is less than 1 equivalent, the sulfonated site tends to be non-uniform, while if it exceeds 50 equivalents, side reactions tend to occur.

  The concentration of the aromatic compound as a raw material in the sulfonating step is not particularly limited as long as the reaction proceeds uniformly when brought into contact with the sulfonating agent, but the side reaction is less likely to occur and the cost advantage due to the suppression of the amount of solvent. From the viewpoint of properties, the content is preferably 1 to 30% by weight based on the weight of the whole compound used in the sulfonation reaction.

  The ion exchange capacity of the sulfonic acid group-containing segment only (hereinafter, the ion exchange capacity may be referred to as IEC) can be set high for IEC as a polymer electrolyte membrane, and also exhibits high proton conductivity under low humidification. 2.0 meq. / G or more is preferable. meq. / G means milliequivalent / g. The IEC of the sulfonic acid group-containing segment is calculated by NMR analysis or the IEC of the electrolyte obtained by copolymerization (which can be easily determined by a conventionally known method such as titration). It can be obtained by dividing by.

  The sulfonic acid group of the precursor of the sulfonic acid group-containing segment may be in a protected form.

  As the transition metal compound, a nickel-based compound and a palladium-based compound are preferably used, and more preferably, a zero-valent nickel complex such as bis (1,5-cyclooctadiene) nickel and tetrakistriphenylphosphine nickel is used. . Further, a divalent nickel compound such as nickel chloride, nickel bromide, or dichlorobistriphenylphosphine nickel may be used in the presence of a reducing agent such as zinc. The zero-valent nickel complex has high coupling reaction activity, is expensive, is sensitive to moisture and oxygen, and needs to be handled with care. Therefore, it is preferable to use a divalent nickel compound.

  In addition, a boronic acid functional group is introduced into one of a sulfonic acid group-containing segment precursor and a hydrophobic segment precursor (metaphenylene segment precursor, metaphenylene segment precursor, and paraphenylene segment precursor), and the other It is also possible to use a Suzuki-Miyaura coupling reaction using a palladium catalyst by introducing a halogen into the catalyst.

  The solvent for the polymerization reaction is preferably a solvent that dissolves a reactant such as a precursor of a metaphenylene segment, a precursor of a paraphenylene segment, and a precursor of a sulfonic acid group-containing segment, and a polymer electrolyte to be generated. Examples thereof include aromatic hydrocarbon solvents, halogen solvents, ether solvents, ketone solvents, amide solvents, sulfone solvents, sulfoxide solvents and the like. Among these, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, etc. are used from the viewpoint of the solubility of the produced polymer electrolyte. Amide solvents, halogen solvents such as dichlorobenzene and trichlorobenzene, and sulfur solvents such as dimethyl sulfoxide are preferred. These polymerization reaction solvents may be used alone or in a combination of two or more.

  When performing a coupling reaction using a transition metal compound, it is preferable to dehydrate the reaction system. The method of dehydration is not particularly limited, but a method of azeotropic dehydration by mixing an azeotropic solvent with the above solvent and heating is preferably used.

  Although there is no limitation in particular as an azeotropic solvent, benzene, toluene, xylene, hexane, cyclohexane, octane, chlorobenzene, dioxane, tetrahydrofuran, etc. can be used, It selects suitably according to the solvent for polymerization reaction.

  The azeotropic dehydration depends on the boiling point of the azeotropic solvent, but is preferably performed in the range of 100 ° C to 200 ° C. If it is less than 100 ° C., the dehydration rate is slow and impractical, and if it exceeds 200 ° C., the polymerization reaction solvent is also distilled off, which is not preferable.

  Depending on the temperature at the time of azeotropic dehydration, the compound represented by the general formula (5) and / or the compound represented by the general formula (6) partially evaporates, and the polymerization yield decreases. A polymer electrolyte having an ion exchange capacity larger than a set value may be obtained. In such a case, it is preferable to add these compounds after cooling the mixture after dehydrating other components, because a polymer electrolyte can be obtained in a high yield.

  When a divalent nickel compound or the like is used as a transition metal compound used for coupling, it is preferable to use a sulfonic acid group-containing segment precursor in which a sulfonic acid group is protected with an alkyl group or the like. If the temperature at the time of dehydration is too high, the protecting group may be eliminated and polymerization may be inhibited. Also in such a case, it is preferable to cool the mixture after dehydrating other components and add the sulfonic acid group-containing segment precursor because a high molecular weight polymer can be obtained in a high yield.

  In one or more embodiments of the present invention, the number average molecular weight of the polymer electrolyte is preferably 1,000 to 500,000, more preferably 5,000 to 200,000, and still more preferably 7,000. ~ 100,000. If the number average molecular weight is less than 1,000, the strength when formed into a film tends to be insufficient, whereas if it is greater than 500,000, the solubility in a solvent tends to be lowered, and the handling property tends to deteriorate. The number average molecular weight of the polymer electrolyte can be determined from the method described in Examples described later.

  In one or more embodiments of the present invention, the polymer electrolyte contains 0.5 to 4.0 meq. / G, preferably 1.2 to 3.8 meq. / G is more preferable, and 1.4 to 3.6 meq. / G is more preferable. 0.5 meq. If it is less than / g, proton conductivity tends to be insufficient, and 4.0 meq. If it exceeds / g, it tends to be difficult to maintain the strength in the case of a film.

  In one or more embodiments of the present invention, the polymer electrolyte can take various structures depending on the combination of raw materials and reactions used. Among these, a polymer electrolyte having a structure represented by the following general formula (4) is particularly preferable.

  In the general formula (4), x is an integer of 1 to 2000, y is an integer of 1 to 1500, z is an integer of 0 to 1500, and y: z is in the range of 100: 0 to 10:90.

  The sulfonic acid group-containing segment in the polymer electrolyte in the general formula (4) is easy to obtain raw materials and has a high sulfonic acid group equivalent in the segment, and is smaller than other sulfonic acid group-containing segments. There is a merit that high proton conductivity can be obtained by the amount used. In the polymer electrolyte represented by the general formula (4), 1,3-dichlorobenzene as a precursor of a metaphenylene segment and 1,4-dichlorobenzene as a precursor of a paraphenylene segment are inexpensive and preferable. .

  In the said General formula (4), x is an integer of 1-2000, y is an integer of 1-1500, z is an integer of 0-1500, Preferably, x is an integer of 2-1000, y and z are respectively , An integer from 5 to 500, more preferably x is an integer from 3 to 400, and y and z are each an integer from 6 to 250. When the value of x is larger than 2000, the hydrophilicity of the polymer electrolyte becomes too high, and there is a possibility that the swelling resistance is lowered or the polymer electrolyte is dissolved in water. On the other hand, when y or z exceeds 1500, it is difficult to dissolve in a solvent and moldability is lowered.

  The polymer electrolyte of the present invention is considered to be used in various industries, and its use (use) is not particularly limited, but a polymer electrolyte membrane, a fuel cell catalyst layer, a fuel cell membrane / Suitable for electrode assemblies and fuel cells.

  The polymer electrolyte membrane according to the present invention is obtained by molding the polymer electrolyte into a membrane by an arbitrary method. As such a film forming method, a known method can be appropriately used. Examples of the known methods include film forming methods from solutions such as hot extrusion methods, inflation methods, melt extrusion molding such as T-die methods, casting methods, and emulsion methods. For example, as a film forming method from a solution, a casting method is exemplified. This is a method in which a polymer electrolyte solution with adjusted viscosity is applied onto a flat plate such as a glass plate using a bar coater, a blade coater or the like, and the solvent is evaporated to obtain a film. Industrially, it is also common to apply a solution continuously from a coating die onto a belt and vaporize the solvent to obtain a long product.

  Furthermore, in order to control the molecular orientation of the polymer electrolyte membrane, the obtained polymer electrolyte membrane is subjected to a treatment such as biaxial stretching or a heat treatment for controlling the crystallinity. Also good. In addition, it is also within the scope of the present invention to add various fillers in order to improve the mechanical strength of the polymer electrolyte membrane or to combine a reinforcing agent such as a glass nonwoven fabric with the polymer electrolyte membrane by pressing. is there.

  As the thickness of the polymer electrolyte membrane, any thickness can be selected according to the application. For example, when considering reducing the internal resistance of the obtained polymer electrolyte membrane, the thinner the polymer electrolyte membrane, the better. On the other hand, in consideration of gas barrier properties and handling properties of the obtained polymer electrolyte membrane, it may not be preferable if the thickness of the polymer electrolyte membrane is too thin. Considering these, the thickness of the polymer electrolyte membrane is preferably 1.2 μm or more and 350 μm or less. When the thickness of the polymer electrolyte membrane is within the range of the above numerical values, handling is improved such that handling is easy and damage is unlikely to occur. In addition, the proton conductivity of the obtained polymer electrolyte membrane can be expressed within a desired range.

  In order to further improve the characteristics of the polymer electrolyte membrane of the present invention, it is possible to irradiate radiation such as electron beam, γ-ray, ion beam and the like. As a result, a crosslinked structure or the like can be introduced into the polymer electrolyte membrane, and the performance may be further improved. In addition, various surface treatments such as plasma treatment and corona treatment can improve properties such as improving adhesion to the catalyst layer on the surface of the polymer electrolyte membrane.

  The polymer electrolyte membrane of the present invention has an ion exchange capacity of 0.5 meq. / G or more, preferably 1.2 meq. / G or more, more preferably 1.4 meq. / G or more is more preferable. Also, 4.0 meq. / G or less, preferably 3.8 meq. / G or less is more preferable, and 3.6 meq. / G or less is more preferable. 0.5 meq. If it is less than / g, proton conductivity tends to be too low, and 4.0 meq. If it exceeds / g, the mechanical strength tends to be remarkably lowered due to swelling with water.

  The catalyst layer for a fuel cell of the present invention contains the polymer electrolyte of the present invention. Specifically, the fuel cell catalyst layer is composed of the above-described polymer electrolyte, a fuel cell catalyst, and, if necessary, a water repellent and a binder resin. By using the polymer electrolyte of the present invention, excellent power generation characteristics suitable for an anode or cathode catalyst layer of a solid polymer fuel cell or a direct methanol fuel cell can be exhibited.

  The fuel cell catalyst used in the present invention may be any conventionally known fuel cell catalyst for those skilled in the art, as long as it contains a conductive catalyst carrier and a catalytically active substance supported on the conductive catalyst carrier. Well, other specific configurations are not particularly limited. Specifically, a catalyst active for the electrode reaction of the fuel cell is used. On the anode side, a catalyst having the ability to oxidize fuel (hydrogen, methanol, etc.) is used. On the cathode side, a catalyst having a reducing ability of an oxidizing agent (such as oxygen) is used.

  Specific examples of the conductive catalyst support include carbon supports having a high surface area such as carbon black, ketjen black (trade name), activated carbon, carbon nanohorn, and carbon nanotube. These materials are preferable in view of chemical stability.

  Specific examples of the catalytically active substance include platinum, cobalt, ruthenium, and the like, and these may be used alone or as an alloy containing at least one of them or as an arbitrary mixture. In particular, considering the oxidizing ability of the fuel, the reducing ability of the oxidizing agent, and durability, platinum or an alloy containing platinum is preferable. If necessary, these may be composed of three or more components using iron, tin, rare earth elements, etc. for stabilization and long life.

  The catalyst layer for a fuel cell of the present invention can be prepared by applying a catalyst ink containing the polymer electrolyte of the present invention, a catalyst for a fuel cell and a solvent on a support and removing the solvent. The solvent can be used without any limitation as long as it can dissolve the polymer electrolyte and does not poison the fuel cell catalyst. The catalyst ink may contain additives such as a non-electrolyte binder, a water repellent, a dispersant, a thickener, and a pore former as necessary. In addition, those additives conventionally known to those skilled in the art can be used, and other specific configurations are not particularly limited.

  The catalyst ink prepared by the above composition and method can be applied by the following coating method depending on the viscosity and the type of substrate. As a method for applying the catalyst ink to the base material, any method known to those skilled in the art may be used, and other specific configurations are not particularly limited. For example, methods using a knife coater, a bar coater, a spray, a dip coater, a spin coater, a roll coater, a die coater, a curtain coater, screen printing, etc. can be enumerated, but not limited thereto.

  In the present invention, when a polymer film is used as the substrate, the catalyst layer transfer sheet for the fuel cell is used, and when a conductive porous sheet is used as the substrate, the gas diffusion electrode for the fuel cell is respectively Can be manufactured.

  The fuel cell membrane / electrode assembly (hereinafter referred to as “MEA”) according to the present invention uses the polymer electrolyte or polymer electrolyte membrane of the present invention. Such MEA can be suitably used for, for example, a polymer electrolyte fuel cell. The methods for producing MEA are conventionally studied polymer electrolyte membranes made of perfluorocarbon sulfonic acid and other hydrocarbon polymer electrolyte membranes (for example, sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfone). A known method performed with oxidized polysulfone, sulfonated polyimide, sulfonated polyphenylene sulfide, or the like is applicable.

  In addition to the examples described above, the polymer electrolyte according to the present invention can be used as an electrolyte of a polymer electrolyte fuel cell known in, for example, Japanese Patent Application Laid-Open No. 2006-179298. Based on these known patent documents, those skilled in the art can easily construct a solid polymer fuel cell using the polymer electrolyte of the present invention.

  Hereinafter, examples will be shown and the embodiment of the present invention will be described in more detail. The present invention is not limited to the following examples, and it goes without saying that various modes are possible for details. Further, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and the present invention is also applied to the embodiments obtained by appropriately combining the disclosed technical means. It is included in the technical scope of the invention.

  Each measurement was performed as follows.

(Measurement of molecular weight)
The molecular weight was measured by GPC method. The conditions are as follows.
GPC measuring device: HLC-8220 (manufactured by Tosoh Corporation)
Column: Super AW 4000 and Super AW 2500 (Showa Denko Co., Ltd.) connected in series Column temperature: 40 ° C
Mobile phase solvent: NMP (N-methylpyrrolidone, LiBr added to 10 mmol / dm3)
Solvent flow rate: 0.3 mL / min
Standard material: TSK standard polystyrene (manufactured by Tosoh Corporation)
Hereinafter, the number average molecular weight converted with standard polystyrene is expressed as Mn, and the weight average molecular weight converted with standard polystyrene is expressed as Mw.

(Solubility)
Using dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP) as solvents, about 30 mg of a polymer electrolyte sample was added to about 5 mL of DMSO or about 5 mL of NMP, respectively, and left at room temperature for 3 hours. If it was difficult to dissolve, the container containing the sample was subjected to ultrasonic treatment at room temperature for 3 hours, and then the solubility was measured according to the following three-stage criteria.
A: It is completely dissolved.
B: There is a part of unmelted residue.
C: Insoluble.

(Measurement of ion exchange capacity)
As a measurement sample, 10 to 20 mg of the membrane after acid treatment was cut out and dried under reduced pressure at 80 ° C., and the dry weight (W _dry ) was measured. When the polymer electrolyte was not soluble in the solvent, 10-20 mg of the crude product after polymerization was similarly dried and then used as a measurement sample. These membranes or the crude product were immersed in a saturated aqueous NaCl solution (30 mL) at room temperature for 24 hours to convert the ionic group from H ⁺ type to Na ⁺ type. Thereafter, HCl contained in the obtained solution was quantified with a 0.01 M NaOH aqueous solution using an automatic potentiometric titrator AT-510 (manufactured by Kyoto Electronics Industry Co., Ltd.), and an ion exchange capacity IEC value using the following formula: Was calculated. Two samples were prepared for the same membrane, and the average value of the two measurements was taken as the calculated IEC value by titration.

(Measurement of swelling rate)
A polymer electrolyte membrane sample cut to about 2 cm × 3 cm was prepared, and the sample was immersed in pure water for 6 hours at room temperature. The dimensional change in the film thickness direction and the weight of the sample immediately after immersion and the sample which was vacuum-dried at 100 ° C. for 2 hours were measured, and the rate of change was calculated. About the film thickness direction, the dimensional change of three places was measured and the average value was made into the result.

(Evaluation of oxidation resistance (Fenton test))
A film (about 30 mg) of about 1 × 3 cm was prepared. This film was added to 50 mL of Fenton solution (3% H ₂ O ₂ containing 2 ppm of FeSO ₄ ) and immersed at 80 ° C. for 1 hour. The membrane after the test was dried, the weight and molecular weight were measured, and the retention rate from the value before the test was calculated.

<Synthesis example 1 of precursor of sulfonic acid group-containing segment>
A 1 L three-necked flask was charged with 2,5-dichlorobenzenesulfonic acid dihydrate (100.5 g, 382 mmol) and water (300 mL), and an aqueous solution of sodium hydroxide (16.05 g, 401 mmol) with stirring. (80 mL) was added at room temperature. The mixture was ice-cooled to precipitate a white solid, and the product was filtered off. The filtrate was ice-cooled again to precipitate a white solid, which was filtered off. The obtained solids were combined and dried under reduced pressure at 105 ° C. to obtain 70.6 g of sodium 2,5-dichlorobenzenesulfonate (yield 74%).

<Synthesis example 2 of precursor of sulfonic acid group-containing segment>
Under a nitrogen atmosphere, 2,2-dimethyl-1-propanol (14.36 g, 162.9 mmol) was added to a 300 mL four-necked flask equipped with a thermometer, a nitrogen inlet tube, and a stirring bar, and pyridine (85 mL). Was added and dissolved. After cooling to 0 ° C., 2,5-dichlorobenzenesulfonyl chloride (20 g, 81.5 mmol) was added and stirred for 2.5 hours. The reaction solution was returned to room temperature and stirring was continued for 6 hours. 4N hydrochloric acid (200 mL) was added to make the reaction solution acidic. Ethyl acetate (200 mL) was added and the two layers were separated. The aqueous layer was extracted with ethyl acetate (100 mL), and the oil layer was washed with saturated aqueous NaHCO ₃ solution (200 mL) and saturated brine (200 mL). The oil layer was dried over sodium sulfate, and the solvent was distilled off under reduced pressure. The obtained crude product was recrystallized from 2-propanol, and a compound in which the sulfonic acid group produced by the reaction represented by the following reaction formula was protected with a 2,2-dimethylpropyl group (2,5-dichlorobenzenesulfone). 19.85 g of acid (2,2-dimethylpropyl acid) was obtained (yield 82%).

<Example 1>
A 2,5-dichlorobenzenesulfonic acid sodium salt obtained in Synthesis Example 1 (2.36 g, 9.48 mmol), 1, 3 into a three-necked flask equipped with a Liebig condenser and a Dean stack trap and purged with nitrogen. -Dichlorobenzene (3.06 g, 20.8 mmol) (molar ratio of 1,3-dichlorobenzene to 1,4-dichlorobenzene = 100: 0), 2,2'-bipyridyl (11.92 g, 76.4 mmol) , Dimethyl sulfoxide (40 mL) and toluene (10 mL) were added, and azeotropic dehydration was performed at 170 ° C. for 3 hours. After the toluene was distilled off, the mixture was cooled to 80 ° C., bis (1,5-cyclooctadiene) nickel (0) (10 g, 36.4 mmol) was added, and the mixture was stirred for 2 hours. The mixture was re-precipitated dropwise in methanol (200 mL). The obtained black solid was washed twice with 6N hydrochloric acid (200 mL), further washed with pure water until the filtrate became neutral, and vacuum dried to obtain 2.56 g of the target polymer electrolyte (crude product). Yield 84%). The reaction formula is as follows.

  The obtained polymer electrolyte was dissolved in both dimethyl sulfoxide (DMSO) and N-methylpyrrolidone (NMP). The molecular weights measured by GPC were Mn = 26,300 and Mw = 78,400. The ion exchange equivalent (IEC) was 2.94 meq. / G. For the measurement of ion exchange equivalent (IEC), an electrolyte membrane prepared as described later was used. The results are summarized in Table 1.

<Example 2>
A 2,5-dichlorobenzenesulfonate sodium salt obtained in Synthesis Example 1 (1.18 g, 4.74 mmol), 1, 3 into a three-necked flask equipped with a Liebig condenser and a Dean stack trap and purged with nitrogen. -Dichlorobenzene (1.377 g, 9.36 mmol), 1,4-dichlorobenzene (0.153 g, 1.04 mmol) (molar ratio of 1,3-dichlorobenzene to 1,4-dichlorobenzene = 90: 10) 2,2′-bipyridyl (5.96 g, 38.2 mmol), dimethyl sulfoxide (20 mL) and toluene (10 mL) were added, and azeotropic dehydration was performed at 170 ° C. for 3 hours. After the toluene was distilled off, the mixture was cooled to 80 ° C., bis (1,5-cyclooctadiene) nickel (0) (5 g, 18.2 mmol) was added and stirred for 2 hours. The mixture was re-precipitated dropwise in methanol (200 mL). The obtained black solid was washed twice with 6N hydrochloric acid (200 mL), further washed with pure water until the filtrate became neutral, and vacuum dried to obtain 1.19 g (crude product) of the target polymer electrolyte. Yield 78%). The reaction formula is as follows.

  The obtained polymer electrolyte was dissolved in both dimethyl sulfoxide (DMSO) and N-methylpyrrolidone (NMP). The molecular weights measured by GPC were Mn = 48,800 and Mw = 96,900. The ion exchange equivalent (IEC) is 3.09 meq. / G. The results are summarized in Table 1.

<Examples 3 to 7>
Copolymerization was carried out in the same manner as in Example 2 except that the charging ratio of 1,3-dichlorobenzene and 1,4-dichlorobenzene was changed to the ratio shown in Table 1 to obtain a polymer electrolyte. The yield, molecular weight, solubility, and IEC of the crude product are summarized in Table 1.

<Example 8>
A 2,5-dichlorobenzenesulfonic acid sodium salt (1.18 g, 4.74 mmol) obtained in Synthesis Example 1 into a three-necked flask equipped with a Liebig condenser and a Dean stack trap and purged with nitrogen, 2,2 '-Bipyridyl (5.96 g, 38.2 mmol), dimethyl sulfoxide (20 mL) and toluene (10 mL) were added, and azeotropic dehydration was performed at 170 ° C. for 3 hours. After the toluene was distilled off, the mixture was cooled to 80 ° C. and 1,3-dichlorobenzene (1.224 g, 8.33 mmol), 1,4-dichlorobenzene (0.306 g, 2.08 mmol) (1,3 -Mole ratio of dichlorobenzene to 1,4-dichlorobenzene = 80: 20) and bis (1,5-cyclooctadiene) nickel (0) (5 g, 18.2 mmol) were added in this order and stirred for 2 hours. . The mixture was re-precipitated dropwise in methanol (200 mL). The obtained black solid was washed twice with 6N hydrochloric acid (200 mL), further washed with pure water until the filtrate became neutral, and vacuum dried to obtain 1.41 g of the target polymer electrolyte (crude product). Yield 92%). The obtained polymer electrolyte was dissolved in dimethyl sulfoxide (DMSO) and N-methylpyrrolidone (NMP). The molecular weight measured by GPC was Mn = 72,900 and Mw = 136,000. The ion exchange equivalent (IEC) is 2.40 meq. / G. The results are summarized in Table 1.

<Examples 9 to 10>
Copolymerization was carried out in the same manner as in Example 8 except that the charging ratio of 1,3-dichlorobenzene and 1,4-dichlorobenzene was changed to the ratio shown in Table 1 to obtain a polymer electrolyte. Yield, molecular weight, solubility, and IEC are summarized in Table 1.

<Comparative Example 1>
0.0306 g (0.208 mmol) of 1,3-dichlorobenzene and 1.50 g (10.2 mmol) of 1,4-dichlorobenzene are used (molar ratio of 1,3-dichlorobenzene to 1,4-dichlorobenzene = 2:98) Except that, 1.14 g of polymer electrolyte was obtained in the same manner as in Example 2 (crude product yield 75%). IEC is 3.23 meq. / G. The obtained polymer electrolyte was not dissolved in DMSO and NMP, and the molecular weight could not be measured. The crude product after polymerization was used for the measurement of ion exchange equivalent (IEC).

<Comparative example 2>
Other than using 1,4-dichlorobenzene (3.06 g, 20.8 mmol) instead of 1,3-dichlorobenzene (molar ratio of 1,3-dichlorobenzene to 1,4-dichlorobenzene = 0: 100) Produced 2.78 g of polymer electrolyte in the same manner as in Example 1 (yield 91%). The reaction formula is as follows. The IEC is 2.3 meq. / G. The obtained polymer electrolyte was not dissolved in DMSO and NMP, and the molecular weight could not be measured.

<Example 11>
1,3-dichlorobenzene (2.448 g, 16.7 mmol), 1,4-dichlorobenzene (0.612 g, 4.4 g) into a three-necked flask equipped with a Liebig condenser and a Dean stack trap and purged with nitrogen. 16 mmol) (molar ratio of 1,3-dichlorobenzene to 1,4-dichlorobenzene = 80: 20), nickel bromide (7.94 g, 36.4 mmol), 2,2′-bipyridyl (11.9 g, 76 0.5 mmol), sodium iodide (10.91 g, 72.8 mmol), dimethylacetamide (DMAc, 80 mL), and toluene (40 mL) were added and heated to 170 ° C. for azeotropic dehydration for 3 hours. After toluene was distilled off, the mixture was cooled to 60 ° C., 2,2-dimethylpropyl 2,5-dimethylpropyl sulfonate (2.82 g, 9.48 mmol) obtained in Synthesis Example 2 and zinc (11 .92 g, 182 mmol) was added and stirred for 3 hours. The mixture was re-precipitated dropwise in methanol (500 mL). The obtained solid was washed twice with 6N hydrochloric acid (500 mL), further washed with pure water until the filtrate became neutral, and vacuum-dried at 60 ° C., so that the sulfonic acid group was 2,2-dimethylpropyl group. A protected polymer was obtained (3.02 g). Next, the obtained polymer (2.48 g) was dissolved in DMAc (20 mL), lithium bromide (1.71 g, 19.7 mmol) was added, and the mixture was stirred at 120 ° C. for 5 hours. The mixture is poured into 6N hydrochloric acid to reprecipitate, the solid is washed with hydrochloric acid, washed with water until the filtrate becomes neutral, and then dried at 105 ° C. under vacuum to obtain 1. 53 g were obtained (total yield of two stages of crude product 50%). The obtained polymer electrolyte was dissolved in both NMP and DMSO. The molecular weights measured by GPC were Mn = 38,900 and Mw = 64,400. The IEC is 3.26 meq. / G. The results are summarized in Table 2.

<Examples 12 to 15>
Copolymerization was carried out in the same manner as in Example 11 except that the charging ratio of 1,3-dichlorobenzene and 1,4-dichlorobenzene was changed to the ratio shown in Table 2 to obtain a polymer electrolyte. The yield, molecular weight, solubility and IEC of the crude product are summarized in Table 2.

<Example 16>
Nickel bromide (7.94 g, 36.4 mmol), 2,2′-bipyridyl (11.9 g, 76.5 mmol) into a nitrogen-purged three-necked flask equipped with a Liebig condenser and a Dean stack trap, Sodium iodide (10.91 g, 72.8 mmol), dimethylacetamide (DMAc, 80 mL) and toluene (40 mL) were added and heated to 170 ° C. for azeotropic dehydration for 3 hours. After the toluene was distilled off, the mixture was cooled to 60 ° C., and 1,3-dichlorobenzene (2.448 g, 16.7 mmol), 1,4-dichlorobenzene (0.612 g, 4.16 mmol) (1,3 -Mole ratio of dichlorobenzene and 1,4-dichlorobenzene = 80: 20), 2,2-dimethylpropyl sulfonate (2,82 g, 9.48 mmol) of 2,5-dichlorobenzenesulfonic acid obtained in Synthesis Example 2. And zinc (11.92 g, 182 mmol) were added in this order and stirred for 3 hours. The mixture was re-precipitated dropwise in methanol (500 mL). The obtained solid was washed twice with 6N hydrochloric acid (500 mL), further washed with pure water until the filtrate became neutral, and vacuum-dried at 60 ° C., so that the sulfonic acid group was 2,2-dimethylpropyl group. A protected polymer was obtained. Next, the obtained polymer (3.72 g) was dissolved in DMAc (20 mL), lithium bromide (2.60 g, 29.9 mmol) was added, and the mixture was stirred at 120 ° C. for 5 hours. The mixture is poured into 6N hydrochloric acid for reprecipitation, the solid is washed with hydrochloric acid, and the filtrate is washed with water until the filtrate is neutral, and then dried at 105 ° C. under vacuum to obtain the desired polymer electrolyte. 75 g was obtained (total yield of two stages of crude product 90%). The obtained polymer electrolyte was dissolved in both NMP and DMSO. The molecular weight measured by GPC was Mn = 47,100 and Mw = 110,000. The IEC is 2.41 meq. / G. The results are summarized in Table 2.

<Examples 17 to 19>
Copolymerization was carried out in the same manner as in Example 16 except that the charging ratio of 1,3-dichlorobenzene and 1,4-dichlorobenzene was changed to the ratio shown in Table 2 to obtain a polymer electrolyte. The yield, molecular weight, solubility and IEC of the crude product are summarized in Table 2. In Tables 1 and 2, “meta: para” means “metaphenylene segment: paraphenylene segment”.

<Comparative Example 3>
Copolymerization was carried out in the same manner as in Example 11 except that 3.06 g (20.8 mmol) of 1,4-dichlorobenzene was used and 1,3-dichlorobenzene was not used to obtain a polymer electrolyte (crude production) Product yield 85%). IEC is 3.11 meq. / G. The obtained polymer electrolyte was not dissolved in DMSO and NMP, and the molecular weight could not be measured.

<Reference Example 1>
A 500 mL four-necked flask equipped with a reflux tube and a DeanStark tube was charged with 4,4′-dichlorodiphenylsulfone (31.6 g, 110 mmol), 4,4′-dihydroxybenzophenone (21.4 g, 100 mmol), potassium carbonate ( 20.7 g, 150 mmol), dimethylacetamide (200 mL), and toluene (50 mL) were added. The mixture was heated to 170 ° C. and stirring was continued for 35 hours while removing generated water. 4,4′-Dichlorodiphenylsulfone (0.5 g) was added, and the mixture was further stirred for 5 hours. The mixture was filtered using filter paper to remove excess potassium carbonate, and then the filtrate was poured into 500 mL of methanol to reprecipitate the product. The product was dried under reduced pressure at 70 ° C. for 4 hours, then washed with 500 mL of pure water twice at 60 ° C., then once with 500 mL of methanol at 60 ° C., and overnight under reduced pressure at 70 ° C. It dried and 41.5g of hydrophobic part oligomers were obtained by reaction shown by the following Reaction Formula. The molecular weight by GPC was Mn = 5400 and Mw = 13900.

  Into a nitrogen-purged three-necked flask equipped with a Liebig condenser and a Dean stack trap, sodium 2,5-dichlorobenzenesulfonate (31.36 g, 126 mmol), the hydrophobic part oligomer obtained above (16 g , 3.5 mmol), 2,2′-bipyridyl (47.68 g, 306 mmol), dimethyl sulfoxide (704 mL) and toluene (176 mL), and dehydration was performed at 170 ° C. for 2 hours. After removing water and toluene, the temperature was lowered to 80 ° C., and bis (1,5-cyclooctadiene) nickel (0) (40 g, 145.6 mmol) was added to initiate polymerization. After reacting for 2 hours, the mixture was allowed to cool, and the reaction product was poured into methanol (2 L) to cause reprecipitation. The obtained solid was washed with 6 mol / L hydrochloric acid (2 × 2 L), and further repeatedly washed with water until the filtrate became neutral. It dried at 105 degreeC under pressure reduction, and obtained 29.9g of target electrolyte (84% of yield of a crude product). The molecular weight by GPC was Mn = 66,600 and Mw = 137,000. The IEC is 2.30 meq. / G.

<Film formation and physical property evaluation>
The polymer electrolytes obtained in Examples 1 to 19 and Reference Example 1 were washed with methylene chloride and methanol and dissolved in DMSO to obtain a solution of about 20% by weight. The obtained polymer electrolyte solution was applied onto a PET film (Toray Lumirror) and dried at 120 ° C. for 12 hours. The obtained film was washed with 6N hydrochloric acid and pure water to obtain a polymer electrolyte membrane having a film thickness of about 25 μm.

  Since the polymer electrolytes of Examples 1 to 19 were polymerized in the ratio of metaphenylene and paraphenylene in the hydrophobic segment in the range of 100: 0 to 10:90, they were dissolved in a solvent and film formation was possible. It was. Among them, the polymer electrolytes of Examples 1 to 4, 8 to 9, 11 to 13, and 16 to 17 have a ratio of metaphenylene and paraphenylene in the hydrophobic segment in the range of 100: 0 to 50:50. The solubility was particularly excellent, and film formation was easy. Furthermore, the electrolytes of Examples 3-4, 8-9, 11-13, and 16-17 have solubility in the hydrophobic segment metaphenylene to paraphenylene ratio of 80:20 to 50:50. And a high molecular weight, it can be said that it is more preferable as a polymer electrolyte membrane.

  In the polymer electrolytes of Comparative Examples 1 to 3, since the ratio of metaphenylene to paraphenylene was out of the range of 100: 0 to 10:90, the solubility in a solvent was low, and film formation could not be performed.

<Swelling degree and Fenton test>
The degree of swelling measurement of the electrolyte membranes of Examples 3 and 12 and Reference Example 1 and the Fenton test were performed. The results are shown in Table 3.

  The electrolyte membranes of Examples 3 and 12 showed substantially the same degree as the electrolyte membrane of Reference Example 1 in the plane direction and a slightly smaller degree of swelling in the film thickness direction. In the polymer electrolyte membranes of Examples 3 and 12, all the main chains are connected by carbon-carbon bonds, and the oxidation resistance is high. Therefore, the shape of the membrane is maintained after the Fenton test, and the weight and molecular weight are the same as before the test. There was little change. On the other hand, since the electrolyte membrane of Reference Example 1 contained hetero bonds such as ether bonds in the main chain, the membrane was broken after the Fenton test and decomposed into small pieces, and the weight and molecular weight were greatly reduced.

Claims (10)

A polymer electrolyte comprising a hydrophobic segment and a hydrophilic segment having a sulfonic acid group and a main chain mainly composed of an aromatic ring,
The hydrophobic segment consists of a segment represented by the following general formula (1), a segment represented by the following general formula (1) and a segment represented by the following general formula (2) arranged randomly. ,
A polymer electrolyte characterized in that each segment is all linked by a carbon-carbon direct bond of an aromatic ring.

(In the general formulas (1) and (2), y represents an integer of 1 to 1500, z represents an integer of 0 to 1500, and y: z is in the range of 100: 0 to 10:90. R ¹ to R ⁸ each independently represents hydrogen, fluorine, an alkyl group, a perfluoroalkyl group, an aryl group, an aralkyl group, or a cyano group.)   2. The polymer electrolyte according to claim 1, wherein in the general formulas (1) and (2), y: z is 100: 0 to 50:50.   The polymer electrolyte according to claim 1 or 2, wherein y: z is 80:20 to 50:50 in the general formulas (1) and (2). The hydrophilic segment having a sulfonic acid group and having a main chain mainly composed of an aromatic ring has one or more structures selected from the structural group represented by the following formula group (3). The polymer electrolyte according to any one of -3.

(In the above formula group (3), m is an integer of 1 to 4, k and l are each an integer of 0 to 4, and k + 1 is an integer of 1 or more. P is an integer of 0 to 10, q is An integer of 0 to 10, and r represents an integer of 1 to 4. X represents at least one structure selected from the group consisting of —CO—, —SO ₂ —, and C (CF ₃ ) ₂ —. , Y is —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _t — (t is an integer of 1 to 10), and —C (CF ₃ ) _2. - represents at least one structure selected from the group consisting of, Z is a direct bond _{or, - (CH 2) o -} (o is an integer of from 1 to _{10), - C (CH 3)} 2 -, - O Represents at least one structure selected from the group consisting of — and —S—, wherein Ar ¹ is —SO ₃ H or —O (CH ₂ ) _s SO ₃ H (s is an integer of 1 to 12). table It represents an aromatic group having a substituent.) The polymer electrolyte according to any one of claims 1 to 5, which has a structure represented by the following general formula (4).

(In the general formula (4), x represents an integer of 1 to 2000, y represents an integer of 1 to 1500, and z represents an integer of 0 to 1500, and y: z is in the range of 100: 0 to 10:90. is there.) A method for producing a polymer electrolyte according to any one of claims 1 to 5,
One or more compounds selected from a compound represented by the following general formula (5), a compound represented by the following general formula (6), and a compound group represented by the formula group (7), A method for producing a polymer electrolyte, comprising copolymerizing in the presence.

(In the general formula (5), the general formula (6) and the formula group (7), Hal is chlorine, bromine or iodine, and R ^{1 to} R ⁸ are each independently hydrogen, fluorine, alkyl group, perfluoro. Represents an alkyl group, an aryl group, an aralkyl group, or a cyano group, m represents an integer of 1 to 4, k and l each represents an integer of 0 to 4, and k + 1 represents an integer of 1 or more, and p represents 0 to 0. An integer of 10, q is an integer of 0 to 10, and r is an integer of 1 to 4. X is selected from the group consisting of —CO—, —SO ₂ —, and —C (CF ₃ ) ₂ —. Represents at least one structure, Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _t — (t is an integer of 1 to 10), — Represents at least one structure selected from the group consisting of C (CF ₃ ) ₂ —, and Z is a direct bond or — (CH ₂ ) _o. - (o is an integer of from 1 to _{10), - C (CH 3)} 2 -, - O-, and .Ar ¹ representing at least one structure selected from the group consisting of -S- are, -SO ₃ An aromatic group having a substituent represented by H or —O (CH ₂ ) _s SO ₃ H (s is an integer of 1 to 12) represents M, hydrogen, an alkali metal, or an alkyl group having 1 to 12 carbon atoms. Represents a cycloalkyl group having 5 to 12 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms.)   The polymer electrolyte membrane using the polymer electrolyte of any one of Claims 1-5.   A fuel cell catalyst layer using the polymer electrolyte according to any one of claims 1 to 5.   The membrane / electrode assembly for fuel cells using the polymer electrolyte of any one of Claims 1-5.   The fuel cell using the polymer electrolyte of any one of Claims 1-5.