JP2010129292A - Polymer electrolyte, polymer electrolyte membrane, and its utilization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer electrolyte for a fuel cell useful for constituting a polymer electrolyte fuel cell and having high conductivity in a low humidification condition. <P>SOLUTION: Ratio λ (antifreeze water) of the number of water molecules existing as the antifreeze water in a polymer electrolyte in a moisture state and the number of ion exchange groups satisfies relational expression 1. [Relational expression 1]: 25.00>λ(antifreeze water)>1.00. Wherein, λ(antifreeze water) is given by dividing the number of water molecules existing as antifreeze water by the number of ion exchange groups. The polymer electrolyte fuel cell constituted with a polymer electrolyte membrane using the polymer electrolyte or a polymer electrolyte composite has high characteristics. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polymer electrolyte used in a solid polymer fuel cell, a polymer electrolyte membrane, a membrane / electrode assembly formed thereby, and a fuel cell.

  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 this. 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 members 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. Application to consumer cogeneration systems and consumer small portable devices is under consideration.

  Here, as the electrolyte membrane used in the polymer electrolyte fuel cell, there is a styrene-based cation exchange membrane developed in the 1950s, but it has poor stability in the fuel cell operating environment and has a sufficient life. No fuel cell has been produced. 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 drawback that it is very expensive because of the high raw materials used and the complicated manufacturing process. In addition, it has been pointed out that it is deteriorated by hydrogen peroxide generated by the electrode reaction and by-product hydroxy radical. Further, due to its structure, there is a limit to the introduction of sulfonic acid groups that are proton conductive 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. Among these, those having a polyether phenylene structure in the main chain have been variously studied from the standpoint of solvent solubility and ease of polymerization.

  For example, in Non-Patent Document 1, poly (2,6-diphenyl-4-phenylene oxide) (hereinafter abbreviated as PPPO) having a structure containing many phenyl groups easily sulfonated in the molecule and having high-temperature stability. And a polyelectrolyte (sulfonated poly (2,6-diphenyl-4-phenyl) having an ion exchange capacity (hereinafter abbreviated as IEC) of 0.7 to 2.8 meq / g, which is obtained by sulfonation treatment. Phenylene oxide) (hereinafter abbreviated as S-PPPO)). However, in this document, it has been shown that S-PPPO is dissolved in water when IEC is 2.6 meq / g or more, and cannot be used as an electrolyte membrane for fuel cells.

  In Patent Document 1, a polymer electrolyte membrane having a poly (2,6-dimethylphenylene oxide) structure and having a high ion exchange capacity ionic group is combined with a fluorine-based polymer to obtain a compatible polymer electrolyte membrane. Yes. It is considered that by increasing the degree of compatibilization, the ionic group was constrained by a hydrophobic non-crosslinked polymer and methanol crossover was reduced. However, poly (2,6-dimethylphenylene oxide) used as the polymer electrolyte has a problem in long-term durability such as decomposition and alteration due to chemical instability of benzylic carbon.

In Patent Document 2, a polyimide structure is introduced to supplement thin film forming ability and solvent resistance, which are insufficient with a polymer electrolyte made of polyether. On the other hand, in order to overcome the property of polyimide, where hydrolyzability is a problem, a contrivance is made to have a sulfonic acid group in the polymer electrolyte at the end of the side chain away from the polyimide structure. However, since the imide ring structure is potentially hydrolyzable and has the imide ring structure in the main chain of the polyelectrolyte, it is assumed that the polyelectrolyte will have a low molecular weight. There is concern about durability.
New Materials For Fuel Cell And Modern Battery Systems II 794-785 JP 2004-319442 A JP 2006-265496 A

  The object of the present invention is to provide a polymer electrolyte useful as a polymer electrolyte membrane of a solid polymer fuel cell. In other words, it is a hydrocarbon-based material that is inexpensive and has a wide variety of chemical structures, has sulfonic acid groups that are advantageous for conductivity, especially in low water conditions, and has a certain amount of water in the membrane in the water-containing state. To provide a polymer electrolyte having excellent proton conductivity and a polymer electrolyte membrane using the polymer electrolyte.

As a result of intensive studies to solve the above problems, the present inventors,
The ratio of the number of water molecules present in the polymer electrolyte as antifreeze water to the number of ion-exchange groups λ (antifreeze water) in the water-containing state satisfies the relational expression 1; We discovered that molecular electrolytes have excellent proton conductivity, especially in low water conditions, and are inexpensive hydrocarbon materials with diverse chemical structures that have excellent proton conductivity. The present inventors have found that a polymer electrolyte can be provided and have completed the present invention. The present invention has been completed based on such novel findings, and includes the following inventions.

[Relational expression 1]
25.00> λ (non-freezing water)> 1.00
(However, λ (antifreeze water) is the number of water molecules present as antifreeze water divided by the number of ion exchange groups.)

The present invention is specifically as follows:
(1) The first aspect of the present invention is that the ratio λ (antifreeze water) of the number of water molecules present in the polymer electrolyte as antifreeze water and the number of ion exchange groups in the water-containing state satisfies the relational expression 1. A feature is a polymer electrolyte having a sulfonic acid group.

[Relational expression 1]
25.00> λ (non-freezing water)> 1.00
(However, λ (antifreeze water) is the number of water molecules present as antifreeze water divided by the number of ion exchange groups.)

  (2) A second aspect of the present invention is obtained by sulfonation of a polymer having at least one structure selected from the group consisting of the following formulas (1) to (4): The polymer electrolyte described.

（式中、Ｘ¹は−Ｏ−、−Ｓ−、−ＮＨ−、−ＣＯ−、−ＳＯ₂−、から選ばれる連結基あるいは直接結合である。Ａｒ¹は０〜４つの置換基を有している、炭化水素系芳香環あるいは酸素、硫黄、窒素のいずれかの原子を含む芳香族へテロ環である。Ａｒ¹の置換基としてはアルキル基、アルコキシ基、置換気を有していても良い炭素数６〜３０のアリール基、ケトン基、スルホン基、フッ素、塩素、臭素であり複数存在する場合、互いに同一であっても異なっていても良い。ｎは整数を表す。）

(Wherein X ¹ is a linking group or a direct bond selected from —O—, —S—, —NH—, —CO—, —SO ₂ —, and Ar ¹ has 0 to 4 substituents. It is a hydrocarbon aromatic ring or an aromatic heterocycle containing any one of oxygen, sulfur, and nitrogen, and the substituent for Ar ¹ has an alkyl group, an alkoxy group, and a substituent. And when there are a plurality of aryl groups having 6 to 30 carbon atoms, ketone groups, sulfone groups, fluorine, chlorine and bromine, they may be the same or different, and n represents an integer.)

（式中、Ｘ¹、Ａｒ¹は前記と同様である。Ｘ²は−Ｏ−、−Ｓ−、−ＮＨ−、−ＣＯ−、−ＳＯ₂−から選ばれる連結基あるいは直接結合である。Ａｒ²は０〜４つの置換基を有している、炭化水素系芳香環あるいは酸素、硫黄、窒素のいずれかの原子を含む芳香族へテロ環である。Ａｒ²の置換基としてはアルキル基、アルコキシ基、置換基を有していても良い炭素数６〜３０のアリール基、ケトン基、スルホン基、フッ素、塩素、臭素であり複数存在する場合、互いに同一であっても異なっていても良い。ｎは整数を表す。）

(Wherein, X ¹ and Ar ¹ are the same as described above. X ² is a linking group selected from —O—, —S—, —NH—, —CO— and —SO ₂ — or a direct bond. Ar ² has 0 to 4 substituents, a hydrocarbon aromatic ring or oxygen, sulfur, Examples of the substituent of .Ar ² is aromatic heterocycle containing any atom of the nitrogen group , An alkoxy group, an optionally substituted aryl group having 6 to 30 carbon atoms, a ketone group, a sulfone group, fluorine, chlorine and bromine, which may be the same as or different from each other. Good, n represents an integer.)

（式中、Ｘ¹、Ｘ²、Ａｒ¹、Ａｒ²は前記と同様である。Ｘ³は−Ｏ−、−Ｓ−、−ＮＨ−、−ＣＯ−、−ＳＯ₂−から選ばれる連結基あるいは直接結合である。Ａｒ³は０〜４つの置換基を有している、炭化水素系芳香環あるいは酸素、硫黄、窒素のいずれかの原子を含む芳香族へテロ環である。Ａｒ³の置換基としてはアルキル基、アルコキシ基、置換基を有していても良い炭素数６〜３０のアリール基、ケトン基、スルホン基、フッ素、塩素、臭素であり複数存在する場合、互いに同一であっても異なっていても良い。ｎは整数を表す。）

(Wherein X ¹ , X ² , Ar ¹ and Ar ² are the same as described above. X ³ is a linking group selected from —O—, —S—, —NH—, —CO— and —SO ₂ —. Alternatively .Ar ³ is a direct bond has 0 to 4 substituents, a hydrocarbon aromatic ring or oxygen, sulfur, the .Ar ³ is aromatic heterocycle containing any atom of the nitrogen The substituent is an alkyl group, an alkoxy group, an aryl group having 6 to 30 carbon atoms which may have a substituent, a ketone group, a sulfone group, fluorine, chlorine, or bromine. Or n may be different. N represents an integer.)

（式中、Ｘ¹、Ｘ²、Ｘ³、Ａｒ¹、Ａｒ²、Ａｒ³は前記と同様である。Ｘ⁴は−Ｏ−、−Ｓ−、−ＮＨ−、−ＣＯ−、−ＳＯ₂−から選ばれる連結基あるいは直接結合である。Ａｒ⁴は０〜４つの置換基を有している、炭化水素系芳香環あるいは酸素、硫黄、窒素のいずれかの原子を含む芳香族へテロ環である。Ａｒ⁴の置換基としてはアルキル基、アルコキシ基、置換基を有していても良い炭素数６〜３０のアリール基、ケトン基、スルホン基、フッ素、塩素、臭素であり複数存在する場合、互いに同一であっても異なっていても良い。ｎは整数を表す。）

(Wherein X ¹ , X ² , X ³ , Ar ¹ , Ar ² , Ar ³ are the same as described above. X ⁴ is —O—, —S—, —NH—, —CO—, —SO _2. Ar ⁴ is a hydrocarbon aromatic ring having 0 to 4 substituents or an aromatic hetero ring containing any one of oxygen, sulfur, and nitrogen atoms. Ar ⁴ substituents are alkyl groups, alkoxy groups, optionally substituted aryl groups having 6 to 30 carbon atoms, ketone groups, sulfone groups, fluorine, chlorine, bromine, and a plurality of them. In this case, they may be the same or different from each other, and n represents an integer.)

  (3) A third aspect of the present invention is the polymer electrolyte according to (1) or (2), which has a hydrophilic segment and a hydrophobic segment in the same molecule.

  (4) A fourth aspect of the present invention is the polymer electrolyte according to any one of (1) to (3), wherein the hydrophilic segment has an ion exchange capacity of 1.0 to 8.5 meq / g.

  (5) A fifth aspect of the present invention is a polymer composed of two or more types of monomers, and has a site where the introduction amount of sulfonic acid groups per minimum repeating unit of the polymer is different from (1) or (2) It is a polymer electrolyte.

  (6) A sixth aspect of the present invention is the polymer electrolyte according to (5), which has an ion exchange capacity of 1.0 to 8.5 meq / g.

  (7) 7th of this invention is a polymer electrolyte membrane containing the polymer electrolyte in any one of (1)-(6).

  (8) An eighth aspect of the present invention is a membrane / electrode assembly including the polymer electrolyte membrane according to (7).

  (9) A ninth aspect of the present invention is a polymer electrolyte fuel cell including the polymer electrolyte membrane according to (7).

  (10) A tenth aspect of the present invention is a polymer electrolyte fuel cell including the membrane electrode assembly according to (8).

  The membrane / electrode assembly and fuel cell utilizing the excellent characteristics of the original electrolyte are prepared by producing the membrane / electrode assembly and fuel cell using the polymer electrolyte and polymer electrolyte membrane of the present invention. be able to. In other words, it is an inexpensive hydrocarbon-based material with a variety of chemical structures, and is a polymer electrolyte with a good balance of antifreeze water and sulfonic acid groups that is advantageous for proton conductivity, especially proton conductivity in low water content conditions. By using such a polymer electrolyte membrane having excellent proton conductivity in a state where moisture is particularly low, a membrane / electrode assembly and a fuel cell having excellent characteristics can be obtained.

  According to the present invention, a polymer electrolyte having a sulfonic acid group, which is a ratio λ (antifreeze water) between the number of water molecules present as antifreeze water in the polymer electrolyte in a water-containing state and the number of ion exchange groups By using a polymer electrolyte having a sulfonic acid group, characterized by satisfying the relational expression 1, it is a low-cost hydrocarbon-based material having a variety of chemical structures, and has a low conductivity and particularly low moisture content. It is possible to provide a polymer electrolyte having a high ion exchange capacity site advantageous in terms of conductivity and having excellent proton conductivity.

[Relational expression 1]
25.00> λ (non-freezing water)> 1.00
(However, λ (antifreeze water) is the number of water molecules present as antifreeze water divided by the number of ion exchange groups.)

  In addition, by using this polymer electrolyte for the polymer electrolyte membrane, it is an inexpensive hydrocarbon material with a variety of chemical structures, which is advantageous in terms of conductivity, particularly in low moisture conditions. A polymer electrolyte membrane having an exchange capacity site and excellent proton conductivity can be obtained.

  An embodiment of the present invention will be described as follows. The present invention is not limited to the following description.

<1. Polymer Electrolyte According to the Present Invention>
The polymer electrolyte of the present invention comprises a hydrophilic segment and a hydrophobic segment. Here, the hydrophilic segment is a site that is substantially sulfonated or has a sulfonic acid group, and the hydrophobic segment is a site that is not substantially sulfonated or a site that does not have a sulfonic acid group. Various methods for synthesizing a polyelectrolyte having a hydrophilic segment and a hydrophobic segment can be applied. When two or more monomers are used, one or more monomers and one or more oligomers or polymers are used. In some cases, two or more oligomers or polymers are used. Each segment consists of three or more monomers or one or more oligomers or polymers. These polyelectrolytes are polyelectrolytes composed of block copolymers having both a hydrophilic segment and a hydrophobic segment in the main chain, or one of the hydrophilic segment and the hydrophobic segment as the main chain, and the other Is a polymer electrolyte made of a graft copolymer having a side chain, or a hydrophilic polymer and a hydrophobic segment randomly combined at multiple points. These segments may be bonded using a bonding aid. Here, the binding aid refers to an aromatic compound having two or more electron withdrawing groups. For example, hexafluorobenzene, decafluorobiphenyl, difluorodiphenyl sulfone, difluorobenzophenone and the like can be mentioned.

<1-1. Method for producing hydrophilic segment>
The hydrophilic segment contained in the polymer electrolyte of the present invention is a site that is substantially sulfonated or a site having a sulfonic acid group. Sulfonation can be carried out using a sulfonating agent such as sulfuric acid, fuming sulfuric acid and chlorosulfonic acid. The sulfonation can be performed at an appropriate stage in the production process of the polymer electrolyte. The step of introducing the sulfonic acid group can be performed at any suitable time after the monomer stage, the oligomer or polymer stage, and the copolymerization with the hydrophobic segment.

  Characteristic of hydrophilic segment is monomer, oligomer or polymer used for polymerization. Sulfuric acid group, sulfonic acid group derivative, or sulfur content such as sulfide bond, sulfoxide bond, sulfone bond that can be converted to sulfonic acid group by oxidation treatment. This is a site formed by sulfonating a polymer having an aromatic ring which has a site or does not have an electron-withdrawing functional group.

  The hydrophilic segment may be copolymerized with the hydrophobic segment after forming the oligomer or polymer, and the monomer that becomes the hydrophilic segment may be copolymerized with the hydrophobic segment.

  As a general method for synthesizing the hydrophilic segment, various methods are possible, and examples thereof include oxidative polymerization and polycondensation. Examples of those synthesized by oxidative polymerization include poly (2,6 dimethylphenylene oxide) and PPPO. Examples of those synthesized by polycondensation include polyetheretherketone and polyetherethersulfone. As a monomer used for polycondensation, various segments can be synthesized by selecting combinations from those in which two or more electron-withdrawing groups are mixed and those in which two or more electron-donating groups are mixed. In general, benzophenone substituted with two halogen atoms such as fluorine and chlorine, diphenylsulfone, and the like are often combined with a compound having a phenolic hydroxyl group at two positions (hereinafter abbreviated as diol 1). Examples of the diol 1 include hydroquinone, bisphenol A, bisphenol S, 4,4′-biphenyl diol, and the like. A sulfonic acid group derivative may be introduced into these monomers in advance.

<1-2. Production method of PPPO>
An example of the production of PPPO is shown as an example of the hydrophilic segment precursor of the present invention. When PPPO is a polymer, a general polymerization method (“New Polymer Experimental 3 Polymer Synthesis / Reaction (2) Synthesis of Condensed Polymer” p. 350-359, (1996) Kyoritsu Publishing Co., Ltd.) can be applied. The electrolyte site may be introduced after the polymerization of a sulfonic acid group, or a monomer having a sulfonic acid group may be polymerized. Various polymerization catalysts in the polymerization reaction step can be selected depending on the reaction conditions. In the case of an organic solvent system such as dichlorobenzene, a catalyst in which a monovalent copper compound and a diamine are combined can be used. Examples of the monovalent copper compound include copper (I) chloride, copper (I) bromide, and iodide. Copper (I) and the like can be listed, and examples of the diamine include tetramethylethylenediamine and tetramethylbutylenediamine. The polymerization reaction is performed in an oxygen or air atmosphere because an atmosphere in which oxygen is present is necessary. Preferably, it is performed in an oxygen atmosphere.

  The solvent in the polymerization reaction step is not particularly limited as long as polymerization is not prohibited, and carbonate compounds (ethylene carbonate, propylene carbonate, etc.), heterocyclic compounds (3-methyl-2-oxazolidinone, 1-methyl-2-pyrrolidone) (Hereinafter abbreviated as NMP)), cyclic ethers (dioxane, tetrahydrofuran, etc.), chain ethers (diethyl ether, ethylene glycol dialkyl ether, etc.), alcohols (methanol, ethanol, isopropanol, etc.), polyhydric alcohols (ethylene Glycol, propylene glycol, etc.) nitrile compounds (acetonitrile, glutarodinitrile, methoxyacetonitrile, etc.), esters (carboxylic acid esters, phosphate esters, phosphonate esters, etc.), aprotic polar substances ( Methyl sulfoxide, sulfolane, dimethylformamide, dimethylacetamide, etc.), non-polar solvents (toluene, xylene, etc.), chlorinated solvents (methylene chloride, ethylene chloride, etc.), water, etc. Aromatic solvents such as chlorobenzene, nitrobenzene and toluene are preferred because of high polymer solubility. Of these, 1,2-dichlorobenzene is preferred because of its high solubility in copper catalysts. These may be used alone or in combination of two or more. What is necessary is just to set the reaction temperature of a polymerization reaction process suitably according to a polymerization reaction. Specifically, it may be set to 20 ° C. to 200 ° C. of the optimum use range of the catalyst, more preferably 40 ° C. to 150 ° C., further preferably 50 ° C. to 120 ° C. If the temperature is lower than this range, the rate of side reactions increases, and if the temperature is higher, the solubility of oxygen decreases and the polymerization does not proceed sufficiently.

  A compound having two hydroxyl groups (hereinafter abbreviated as diol 2) or the like as an initiator may be added to the polymerization reaction step of the present invention, and examples thereof include compounds represented by the following formulas (5) and (6). A product produced by adding diol 2 is referred to as telechelic PPPO.

（式中、Ｒ¹〜Ｒ⁴は−Ｈ、−ＣＨ₃、−Ｃ₆Ｈ₅、−ＣＦ₃、−Ｃ₆Ｆ₅、−Ｆ、−Ｃｌ、−Ｂｒ、−Ｉのうちのいずれか。）

(In the formula, R ^{1 to} R ⁴ are any ^one of —H, —CH ₃ , —C ₆ H ₅ , —CF ₃ , —C ₆ F ₅ , —F, —Cl, —Br, and —I. )

（式中、Ｘは単結合、−ＣＨ₂−、−ＣＦ₂−、−Ｃ（ＣＨ₃）₂−、−Ｃ（ＣＦ₃）₂−、−ＣＯ−、−ＳＯ₂−のうちのいずれか。Ｒ¹〜Ｒ⁸は−Ｈ、−ＣＨ₃、−Ｃ₆Ｈ₅、−ＣＦ₃、−Ｃ₆Ｆ₅、−Ｆ、−Ｃｌ、−Ｂｒ、−Ｉのうちのいずれか。）なお、重量平均分子量は、５００〜１，０００，０００が好ましい。

(Wherein, X is a single _{bond, -CH 2 -, - CF 2} -, - C (CH 3) 2 -, - C (CF 3) 2 -, - CO -, - SO 2 - one of the R ^{1 to} R ⁸ are any ^one of —H, —CH ₃ , —C ₆ H ₅ , —CF ₃ , —C ₆ F ₅ , —F, —Cl, —Br, and —I.) The weight average molecular weight is preferably 500 to 1,000,000.

  In the polymerization reaction step, it is preferable to perform a stopping operation, which can be performed by cooling, diluting, blocking oxygen, or adding a polymerization inhibitor. You may take out the polymer | macromolecule produced | generated after the polymerization reaction process. Further purification steps may be added.

<1-3. Method for producing hydrophobic segment>
The hydrophobic segment contained in the polymer electrolyte of the present invention is a site that is not substantially sulfonated or a site that does not have a sulfonic acid group. The hydrophobic segment is a site that is not substantially sulfonated when the hydrophilic segment is sulfonated.

  The characteristic of the hydrophobic segment is that it does not have a sulfonic acid group or a substituent that can be derived to a sulfonic acid group, or has no substituent that can be derived to a sulfonic acid group. Any site that is substantially not sulfonated in the sulfonation process, such as a sulfonation rate that is twice or more slower, or few sites to be sulfonated, such as a site mainly composed of an aromatic ring having an electron-withdrawing functional group It is.

  The hydrophobic segment may be copolymerized with the hydrophilic segment after forming the oligomer or polymer, or may be copolymerized with the hydrophilic segment while forming the hydrophobic segment from the monomer.

  A general method for synthesizing the hydrophobic segment can also be synthesized in the same manner as the hydrophilic segment, and examples thereof include poly (ether ketone), poly (ether sulfone) (hereinafter abbreviated as PES), and the like. Depending on the combination of monomers used for polycondensation, various segments such as those in which two or more electron-withdrawing groups are mixed and those in which two or more electron-donating groups are mixed can be synthesized. In general, benzophenone substituted with two halogen atoms such as fluorine and chlorine, or diphenyl sulfone, etc., a compound having a phenolic hydroxyl group at two locations and an electron withdrawing group in part (hereinafter referred to as diol 3) Abbreviated). Examples of the diol 3 include 4,4′-dihydroxybenzophenone, bis (4-hydroxyphenyl) sulfone, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, and the like.

<1-4. Manufacturing method of PES>
An example of production of PES is shown as an example of the hydrophilic segment precursor of the present invention. When PES is a polymer, PES is a general method of polymerization ("New Polymer Experimental 3 Polymer Synthesis / Reaction (2) Condensed Polymer Synthesis" p.7-24, (1996) Kyoritsu Publishing Co., Ltd.) can be applied. The polymerization reaction is preferably performed in an atmosphere that does not contain much oxygen, and is preferably performed in an inert gas atmosphere, such as a nitrogen gas atmosphere or an argon gas atmosphere. The solvent in the polymerization reaction step is not particularly limited as long as polymerization is not prohibited, and heterocyclic compounds (3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone (hereinafter abbreviated as DMI), 1-methyl-2-pyrrolidone (hereinafter abbreviated as NMP), cyclic ethers (dioxane, tetrahydrofuran, etc.), chain ethers (diethyl ether, ethylene glycol dialkyl ether, etc.), aprotic polar substances (dimethyl sulfoxide, sulfolane) Dimethylformamide, dimethylacetamide, etc.), nonpolar solvents (toluene, xylene, etc.), chlorinated solvents (methylene chloride, ethylene chloride, etc.), water, etc. Imidazolidinone What amide solvents are preferable. These may be used alone or in combination of two or more. As the base, potassium carbonate is often used because it is inexpensive, but sodium carbonate, calcium carbonate, magnesium carbonate, cesium carbonate, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, and the like can be used.

  What is necessary is just to set the reaction temperature of a polymerization reaction process suitably according to a polymerization reaction. Specifically, it may be set to 20 ° C to 300 ° C, more preferably 60 ° C to 260 ° C, and still more preferably 80 ° C to 200 ° C. If the temperature is lower than this range, the reaction rate is remarkably reduced, and if the temperature is higher, the decomposition of the monomer and polymer may proceed.

  In the polymerization reaction step, it is preferable to perform a stopping operation, which can be performed by cooling, diluting, or adding a polymerization inhibitor. You may take out the polymer | macromolecule produced | generated after the polymerization reaction process. Further purification steps may be added.

<1-5. Production of block copolymer>
Either a hydrophilic segment or a hydrophobic segment is oligomerized or polymerized and then linked to obtain a block copolymer, and one of them is oligomerized or polymerized, and the other segment component is added thereto for polymerization. Thus, there is a method of obtaining a block copolymer. There is also a method of using a linking agent at the binding site of each segment. As the synthesis conditions, the same technique as that for the production method of PPPO and PES can be applied. In either case, a material obtained by oligomerizing or polymerizing at least one of a hydrophilic segment and a hydrophobic segment is used. At least one of the oligomers or polymers used for copolymerization has fluorine, chlorine or sulfonic acid ester at the terminal, and at least one of them has a hydroxyl group, mercapto group, amino group, or metal salt thereof at the terminal. It is preferable to have.

<1-6. Method for sulfonation of polymer electrolyte precursor>
Examples of the sulfonating agent in the sulfonation step include sulfuric acid, chlorosulfonic acid, fuming sulfuric acid and the like, and in many cases, chlorosulfonic acid is preferable because it has an appropriate reactivity. The solvent in the sulfonation step is not particularly limited as long as it does not inhibit the reaction. Cyclic ethers (dioxane, tetrahydrofuran, etc.), chain ethers (diethyl ether, ethylene glycol dialkyl ether, etc.), nonpolar solvents (toluene) , Xylene, etc.) Chlorine solvents (methylene chloride, ethylene chloride, etc.), sulfonic acids (methanesulfonic acid, trifluoromethanesulfonic acid, etc.), sulfuric acid, water can be listed, among which methylene chloride, 1,2-dichloroethane, etc. Chlorinated solvents are preferred. These may be used alone or in combination of two or more. What is necessary is just to set the reaction temperature of a sulfonation process suitably according to reaction, Specifically, what is necessary is just to set to -80 to 200 degreeC which is the optimal use range of a sulfonating agent, More preferably, it is -50 to 120 degreeC. ° C, more preferably -20 ° C to 80 ° C. If the temperature is lower than this range, the reaction is slow, and if the temperature is high, a rapid reaction occurs and sulfonation may proceed to other than the intended site.

<1-7. Number of ion-exchange groups contained in the polymer electrolyte in the present invention>
The number of ion exchange groups contained in the polymer electrolyte in the present invention can be determined experimentally by measuring the ion exchange capacity, and can also be determined from the theoretical ion exchange capacity at the time of preparing the polymer electrolyte. Preferably, the ion exchange capacity is measured experimentally. Since the value of ion exchange capacity is equal to the number of ion exchange groups contained per gram of polymer electrolyte, the value of ion exchange capacity is the number of ion exchange groups per unit weight.

<1-8. Number of water molecules present as antifreeze water in the polymer electrolyte in the present invention>
In the water-containing state of the present invention, the number of water molecules present as antifreeze water in the polymer electrolyte is determined by calculation from a value obtained using a differential scanning calorimetry (DSC) method. That is, after immersing the polymer electrolyte in water at 20 ° C. for 12 hours, the polymer electrolyte is removed from the water, the surface adhering water is wiped off with gauze, and the weight (Gp) is measured in advance. After crimping in a closed type data container, measure the total weight (Gw) of the sample and the closed type sample container as quickly as possible, and immediately perform DSC measurement. The measurement temperature program is to cool from room temperature to −30 ° C. at a rate of 10 ° C./min, and then increase the temperature to 5 ° C. at a rate of 0.3 ° C./min. The bulk water amount (Wf) is obtained using the formula (n1), the low melting point water amount (Wfc) is obtained using the following formula (n2), and the total water content (Wt) is obtained using the following formula (n3). By subtracting these values, the amount of antifreeze water (Wnf) is obtained.

  Here, the bulk water amount (Wf), the low melting point water amount (Wfc), the antifreeze water amount (Wnf), and the total water amount (Wt) are values represented by the weight per unit weight of the dried sample. m is the weight of the dried sample, dq / dt is the DSC heat flux signal, T0 is the melting point of the bulk water, and Delta H0 (ie, expressed in triangles and H0) is the melting enthalpy at the melting point of the bulk water (T0). .

  The number of water molecules present as antifreeze water per unit weight is obtained by dividing the amount of antifreeze water (Wnf) obtained by the above calculation method by the molecular weight of water.

<1-9. Regarding λ (non-freezing water)>
A polymer electrolyte having a sulfonic acid group, wherein the ratio λ (antifreeze water) of the number of ion exchange groups per unit weight obtained by the above method and the number of water molecules present as antifreeze water satisfies the relational expression 1. It is a polymer electrolyte having excellent proton conductivity under low humidification conditions.

[Relational expression 1]
25.00> λ (non-freezing water)> 1.00
(However, λ (antifreeze water) is the number of water molecules present as antifreeze water divided by the number of ion exchange groups.)
Among these, a more preferable range is 25.00> λ (antifreeze water)> 1.40.

<1-10. DSC measurement conditions>
The DSC measurement conditions are as follows.
DSC device: DSC Q100 manufactured by TA Instruments
Data processing device: TRC-THADAP-DSC manufactured by Toray Research Center
Measurement temperature range: -55 ° C to 5 ° C
Temperature increase rate: 0.3 ° C / min
Sample amount: about 5mg
Sample container: Aluminum sealed sample container Temperature / calorie calibration: Pure water (0.0 ° C., heat of fusion 79.7 cal / g)

<1-11. Polymer Electrolyte Membrane According to the Present Invention>
The polymer electrolyte membrane according to the present invention is obtained by molding the above polymer electrolyte and polymer electrolyte composite into a film shape by an arbitrary method. As such a film forming method, a known method can be appropriately used. Examples of the leaving method include a film forming method from a solution such as a hot extrusion method, an inflation method, a melt extrusion molding method such as a T-die method, a casting method, and an emulsion method. As an example of the melt molding method, a polymer electrolyte membrane is produced by melt extrusion molding. Specifically, a method in which a material is put into an extruder in which a T die is set and film formation is performed while melt kneading can be applied. Furthermore, it is also possible to perform the above-mentioned combination in this step. An example of a film forming method from a solution is a casting method. This is a method in which a polymer electrolyte or polymer electrolyte complex solution with adjusted viscosity is applied onto a flat plate such as a glass plate using a bar coater, blade coater, etc., and the solvent is evaporated to obtain a film. is there. 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.

  The thickness of the manufactured polymer electrolyte membrane can be selected arbitrarily depending on the application. For example, in consideration of reducing the internal resistance of the obtained polymer electrolyte membrane, the polymer film is preferably as thin as possible. On the other hand, when the gas, methanol barrier property and handling property of the obtained polymer electrolyte membrane are taken into consideration, 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.

  The polymer electrolyte membrane can be introduced with a sulfonic acid group after being formed. In that case, the method for forming the polymer electrolyte membrane can be read as the method for forming the polymer electrolyte membrane precursor film. That is, a method for producing a film from a polymer that introduces a sulfonic acid group or a complex that includes a polymer that introduces a sulfonic acid group is exemplified. In this case, the polymer electrolyte membrane is finally obtained by sulfonating the film.

  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.

  In the polymer electrolyte having a hydrophilic segment and a hydrophobic segment, phase separation comprising a hydrophilic portion or a hydrophobic portion can be observed with a transmission electron microscope or the like.

<1-12. Membrane / electrode assembly and fuel cell according to the present invention>
The polyelectrolyte and polyelectrolyte composite according to the present invention are considered to have various industrial uses, and the use (use) is not particularly limited. For example, a membrane / electrode assembly ( (Hereinafter referred to as MEA). Such MEAs can be used, for example, in fuel cells, particularly solid polymer fuel cells, and fuel cells such as direct methanol fuel cells.

  That is, the present invention may include MEA and fuel cell using the polymer electrolyte and polymer electrolyte composite.

  According to the membrane / electrode assembly or the fuel cell, it is a hydrocarbon-based material having a variety of chemical structures as described above, which is advantageous in terms of conductivity, particularly conductivity in a low moisture state. Since it has an ion exchange capacity site, a polymer electrolyte membrane having excellent proton conductivity, and a catalyst layer binder, it has high power generation characteristics.

  Next, an embodiment of a polymer electrolyte fuel cell using the polymer electrolyte membrane of the present invention will be described with reference to the drawings. In the present embodiment, a polymer electrolyte fuel cell will be described as an example.

  FIG. 1 is a diagram schematically showing a cross-sectional structure of a main part of a polymer electrolyte fuel cell using a polymer electrolyte membrane according to the present embodiment. As shown in the figure, a polymer electrolyte fuel cell 10 according to the present embodiment includes a polymer electrolyte membrane 1, catalyst layers 2 and 2, diffusion layers 3 and 3, and separators 4 and 4.

  The polymer electrolyte membrane 1 is located substantially at the center of the cell of the solid polymer fuel cell 10. The catalyst layer 2 is provided in contact with the polymer electrolyte membrane 1. The diffusion layer 3 is provided adjacent to the catalyst layer 2, and a separator 4 is disposed on the outer side thereof. The separator 4 is formed with a flow path 5 for feeding fuel gas or liquid (such as aqueous methanol solution) and an oxidant. In other words, these members are configured as cells of the polymer electrolyte fuel cell 10.

  Generally, a polymer electrolyte membrane 1 with a catalyst layer 2 joined, or a polymer electrolyte membrane 1 with a catalyst layer 2 and a diffusion layer 3 joined together is a membrane / electrode assembly (also referred to as MEA in this specification). It is used as a basic member of a polymer electrolyte fuel cell.

  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 a sulfonated polysulfone, a sulfonated polyimide, a sulfonated polyphenylene sulfide, or the like is applicable.

  An example of a specific method for producing MEA is shown below, but the present invention is not limited to this.

  The catalyst layer 2 is formed by preparing a dispersion solution for forming a catalyst layer by dispersing a metal-supported catalyst in a solution or dispersion solution of a catalyst layer binder that is a polymer electrolyte. The dispersion solution is applied onto a release film such as PTFE by spraying, and the solvent in the dispersion solution is dried and removed to form a predetermined catalyst layer 2 on the release film. The catalyst layer 2 formed on the release film is disposed on both surfaces of the polymer electrolyte membrane 1, and hot-pressed under predetermined heating and pressurizing conditions to join the polymer electrolyte membrane 1 and the catalyst layer 2 and release them. The MEA in which the catalyst layers 2 are formed on both surfaces of the polymer electrolyte membrane 1 can be produced by peeling the mold film.

  Also, a catalyst-carrying gas diffusion electrode in which the dispersion solution is coated on the diffusion layer 3 using a coater or the like, the solvent in the dispersion solution is dried and removed, and the catalyst layer 2 is formed on the diffusion layer 3 Are arranged on both sides of the polymer electrolyte membrane 1, and the catalyst layer 2 side of the catalyst-carrying gas diffusion electrode is placed on both sides of the polymer electrolyte membrane 1 by hot pressing under predetermined heating and pressurizing conditions. An MEA in which the catalyst layer 2 and the diffusion layer 3 are formed can be manufactured. In addition, you may use a commercially available gas diffusion electrode (made by USA E-TEK company etc.) for the said catalyst carrying | support gas diffusion electrode.

  Examples of the polymer electrolyte solution include an alcohol solution of a perfluorocarbon sulfonic acid polymer compound (such as Nafion (registered trademark) solution manufactured by Aldrich) or a sulfonated aromatic polymer compound (eg, sulfonated polyether ether ketone). , Sulfonated polyethersulfone, sulfonated polysulfone, sulfonated polyimide, sulfonated polyphenylene sulfide, etc.) can be used. Of course, the catalyst layer binder of the present invention can also be used. As the metal-supported catalyst, conductive particles having a high specific surface area can be used as a carrier, and examples thereof include carbon materials such as activated carbon, carbon black, ketjen black, vulcan, carbon nanohorn, fullerene, and carbon nanotube.

  Any metal catalyst may be used as long as it promotes the fuel oxidation reaction and oxygen reduction reaction, and the fuel electrode and the oxidant electrode may be the same or different. For example, noble metals such as platinum and ruthenium or alloys thereof can be exemplified, and a promoter for promoting their catalytic activity or suppressing poisoning by reaction by-products may be added.

  The dispersion solution for forming the catalyst layer may be appropriately diluted with water or an organic solvent in order to adjust the viscosity so that it can be easily applied by spraying or coated by a coater. Moreover, you may mix fluorine-type compounds, such as tetrafluoroethylene, in order to provide water repellency to the catalyst layer 2 as needed.

  As the diffusion layer 3, a porous conductive material such as carbon cloth or carbon paper can be used. In order to promote the diffusibility of the fuel and the oxidant and the discharge of reaction by-products and unreacted substances, it is preferable to use those which are coated with tetrafluoroethylene or the like to impart water repellency. Further, an adhesive layer made of a polymer electrolyte as described above may be provided between the polymer electrolyte membrane 1 and the catalyst layer 2 as necessary.

  The conditions for hot pressing the polymer electrolyte membrane 1 and the catalyst layer 2 under heating and pressurizing conditions need to be appropriately set according to the type of polymer electrolyte contained in the polymer electrolyte membrane 1 and the catalyst layer 2 to be used. is there. The above-mentioned condition is that the polymer electrolyte contained in the polymer electrolyte membrane 1 or the catalyst layer 2 is generally below the thermal degradation or thermal decomposition temperature of the polymer electrolyte contained in the polymer electrolyte membrane 1 or the catalyst layer 2. It is preferable that the glass transition point and the softening point are higher than the glass transition point, and the temperature condition is higher than the glass transition point and the softening point of the polymer electrolyte contained in the polymer electrolyte membrane 1 and the catalyst layer 2.

  As the pressurizing condition, it is preferable that the pressure is in the range of about 0.1 MPa or more and 20 MPa or less because the polymer electrolyte membrane 1 and the catalyst layer 2 are in sufficient contact with each other and there is no deterioration in characteristics due to significant deformation of the material used. In particular, when the MEA is formed only from the polymer electrolyte membrane 1 and the catalyst layer 2, the diffusion layer 3 may be disposed outside the catalyst layer 2 and used only by contacting without being joined.

  The MEA obtained by the above method is inserted between a pair of separators 4 in which a flow path 5 for feeding fuel gas or liquid and an oxidant is formed, and the solid according to the present embodiment. A polymer fuel cell 10 is obtained.

  As the separator 4, a conductive material such as carbon graphite or stainless steel can be used. In particular, when a metal material such as stainless steel is used, it is preferable to perform a corrosion resistance treatment.

  For the polymer electrolyte fuel cell 10 described above, a gas containing hydrogen as a main component or a gas or liquid containing methanol as a main component as a fuel gas or liquid, and a gas containing oxygen (oxygen or oxygen) as an oxidant. The solid polymer fuel cell generates electric power by supplying air) to the catalyst layer 2 via the diffusion layer 3 from the respective separate flow paths 5. At this time, for example, when a hydrogen-containing liquid is used as the fuel, a direct liquid fuel cell is obtained, and when methanol is used, a direct methanol fuel cell is obtained. That is, it can be said that the above-described embodiment exemplified for the polymer electrolyte fuel cell 10 can be applied to a direct liquid fuel cell and a direct methanol fuel cell as they are.

  In addition, the polymer electrolyte fuel cell 10 according to the present embodiment can be used alone or in a stacked manner to form a stack, or a fuel cell system incorporating them.

  In addition to the examples described above, the polymer electrolyte membrane according to the present invention is disclosed in JP 2001-313046, JP 2001-313047, JP 2001-93551, and JP 2001-93558. JP-A-2001-93561, JP-A-2001-102069, JP-A-2001-102070, JP-A-2001-283888, JP-A-2000-268835, JP-A-2000-268836, It can be used as an electrolyte membrane of a polymer electrolyte fuel cell or a direct methanol fuel cell, which is publicly known in Japanese Laid-Open Patent Publication No. 2001-283893. Based on these known patent documents, those skilled in the art can easily construct a solid polymer fuel cell or a direct methanol fuel cell using the polymer electrolyte membrane of the present invention.

  Hereinafter, examples will be shown, and the embodiment of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail. 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.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these Examples, In the range which does not change the summary, it can change suitably.

[Reference Example 1]
(Synthesis of telechelic PPPO using tetraphenylbisphenol A)
1,2-dichlorobenzene (50 ml), copper bromide (3.4 g) and N, N, N ′, N′-tetramethylethylenediamine (2.8 g) were mixed in an eggplant flask and stirred at room temperature for 15 minutes. . Subsequently, tetraphenylbisphenol A (5.8 g) was added under an oxygen stream, heated to 80 ° C., and stirred for 30 minutes. A solution of 2,6-diphenylphenol (50.5 g) in 1,2-dichlorobenzene (50 ml) was added dropwise thereto and reacted at 80 ° C. for 5 hours. After completion of the reaction, the reaction solution is cooled to room temperature, concentrated hydrochloric acid (20 ml) and hypophosphorous acid (20 ml) are added and stirred, water is then added to remove the aqueous phase, the organic phase is washed with water, and the organic phase is carbonated. After adding an aqueous sodium hydrogen solution and stirring, the aqueous phase was removed, the organic phase was washed twice with water, and the organic phase was dropped into methanol (1500 ml). The precipitated polymer was separated by filtration and dried under reduced pressure at 80 ° C. for 24 hours to obtain 52 g (Mn = 4120) of a pale yellow polymer. (Hereafter abbreviated as PPPO1)

[Reference Example 2]
(Preparation of PES having both terminal hydroxy groups)
Bisphenol S (7.12 g), difluorodiphenyl sulfone (7.26 g), potassium carbonate (5.61 g) and DMI (30 ml) were mixed in an eggplant flask filled with nitrogen, and heated to 200 ° C. with stirring. After 8 hours, the mixture was cooled to room temperature, precipitated in water, ground with a mixer, washed with water, dissolved in dichloromethane, and precipitated again in methanol. The solid was filtered and dried at 60 ° C. for 24 hours to obtain 12.6 g (Mn = 13392) of a white solid. (Hereafter abbreviated as PES1)

[Reference Example 3]
(Decafluorobiphenyl modification of telechelic PPPO polymer terminal)
Telechelic PPPO polymer PPPO1 (5.0 g) obtained by the above method, decafluorobiphenyl (2.4 g), potassium carbonate (0.7 g) and DMI 25 ml were mixed and reacted at 100 ° C. for 6 and a half hours under nitrogen. After completion of the reaction, the reaction solution was cooled to room temperature and precipitated into water. The solid was pulverized with a mixer, filtered, and dried to obtain 4.9 g of a pale yellow solid. The product confirmed the completion of the terminal modification reaction by ¹ H-NMR, and the removal of the raw material decafluorobiphenyl was confirmed by ¹⁹ F-NMR. The obtained polymer is hereinafter abbreviated as FPPPO1.

[Example 1]
PES1 (4.0 g) and potassium carbonate (0.09 g) were mixed with DMI (15 ml), heated and stirred at 140 ° C. for 2 hours under nitrogen, FPPPO1 (1.8 g) was added, and 120 ° C. for 2 hours. Stir with heating. The reaction solution was cooled to room temperature and added to water to precipitate a solid. After pulverizing with a mixer, filtering and drying, a pale yellow solid (5.6 g) was obtained. The molecular weight of the obtained polymer was Mn = 33745, Mw = 72229, and Mw / Mn = 2.140.

  Subsequently, the obtained polymer (2.5 g) was dissolved in 50 ml of dichloromethane, and dropwise added to a solution of 250 ml of dichloromethane in which chlorosulfonic acid (9.0 g) was dissolved while cooling the flask with water. After 30 minutes, the supernatant was removed, and the precipitated solid was washed twice with dichloromethane. Water was then added to give a white solid. The white solid was pulverized with a mixer and filtered. At this time, the filtrate was washed with water until the pH of the filtrate became almost neutral. The residue was dried to obtain 2.4 g of a pale yellow solid.

  After 1 g of the obtained solid was dissolved in DMSO, the solution was cast on a glass plate, vacuum-dried at 60 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours. The ion exchange capacity of this membrane was 1.63 meq / g. The results of evaluating the properties of the obtained polymer electrolyte membrane are shown in Table 1. Tables 2 and 3 show the evaluation results of proton conductivity under different conditions of temperature and relative humidity.

[Reference Example 4]
Under a nitrogen atmosphere, a solution of 16.6 g (120 mmol) of dimethoxyhydroquinone in CH ₂ Cl ₂ (100 ml) was cooled to an internal temperature of −15 ° C. To this, 17.4 g (130.8 mmol) of aluminum chloride and 15.6 ml (132 mmol) of 4-fluorobenzoyl chloride were sequentially added, and the mixture was stirred at the same temperature for 19 hours. After confirming the completion of the reaction by TLC, the reaction was stopped by pouring into water (500 ml). After extraction with CH ₂ Cl ₂ , the organic phase was washed with 10 wt% NaOH aqueous solution (300 ml), extracted again with CH ₂ Cl ₂ , washed with water, and the aqueous layer was removed. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure to obtain 30.6 g of 2,4-dimethoxy-4′-fluorobenzophenone as a slightly yellow oil.

[Reference Example 5]
(Synthesis of PPPO)
Copper bromide (60 mg), 4-dimethylaminopyridine (82 mg) and ethanol (35 ml) were added to the reactor, and 2,6-diphenylphenol (5 g) dissolved in methyl ethyl ketone (8 ml) was added thereto. After stirring for 15 hours at room temperature in an oxygen atmosphere to gradually precipitate low molecular weight poly (2,6-diphenylphenylene ether), a 10% aqueous solution of ethylenediaminetetraacetic acid tripotassium salt was added and heated at 50 ° C. Stir. Next, hydroquinone is added little by little, and after decolorization, the slurry poly (2,6-diphenylphenylene ether) is filtered, washed with alcohol, and dried under reduced pressure at 80 ° C. for 24 hours. 4.3 g (Mn = 2300) of 6-diarylphenylene ether) was obtained. (Hereafter abbreviated as PPPO2)

[Reference Example 6]
N, N-dimethylacetamide (10 ml) and o- containing PPPO2 (3.3 g), 2,4-dimethoxy-4′-fluorobenzophenone (0.36 g) and potassium carbonate (0.27 g) under nitrogen atmosphere. A mixed solution of dichlorobenzene (5 ml) was stirred under an oil bath heating condition of 180 ° C. for 24 hours. After the completion of the reaction was confirmed by TLC, the reaction was stopped by pouring into water (50 ml). After extraction with CH ₂ Cl ₂ , precipitation was performed by adding dropwise to methanol (300 ml) to obtain 3.1 g of the target product as a solid. (Hereinafter abbreviated as BPPPO1)

[Reference Example 7]
Under a nitrogen atmosphere, a CH ₂ Cl ₂ (10 ml) solution containing BPPPO1 (2.56 g) was cooled to an internal temperature of −15 ° C. To this, ₃ ml of a 1MCH ₂ Cl ₂ solution of BBr ₃ was added dropwise, and the mixture was stirred at room temperature for 15 hours. After the completion of the reaction was confirmed by TLC, the reaction was stopped by pouring into water (50 ml). After extraction with ethyl acetate, the extract was dried over magnesium sulfate and concentrated under reduced pressure. This was purified by silica gel column chromatography to obtain 1.3 g of yellow crystals. (Hereinafter abbreviated as BPPPO2)

[Reference Example 8]
(Preparation of PES having both terminal chloro groups)
Bisphenol S (5.0 g), dichlorodiphenyl sulfone (11.5 g), potassium carbonate (7.7 g) and DMI (30 ml) were mixed in an eggplant flask filled with nitrogen and heated to 200 ° C. with stirring. After 8 hours, the mixture was cooled to room temperature, precipitated in water, ground with a mixer, washed with water, dissolved in dichloromethane, and precipitated again in methanol. The solid was filtered and dried at 60 ° C. for 24 hours to obtain 12.6 g (Mn = 620) of a white solid. (Hereafter abbreviated as PES2)

[Example 2]
Under a nitrogen atmosphere, 1,3-dimethyl-2-imidazolidinone (1.5 ml) and o-dichlorobenzene (0. 0. 1) containing BPPPO2 (0.5 g), PES2 (1.31 g) and potassium carbonate (44 mg). 8 ml) and toluene (0.5 ml) were stirred for 1 hour under oil bath heating conditions at 160 ° C., water and toluene were removed azeotropically from the system, and the oil bath temperature was increased to 180 ° C. The polymerization was carried out for 15 hours. The resulting polymer was dropped into 100 ml of water, neutralized by adding an acid, and the polymer was collected by filtration. After stirring and washing the polymer with hot water, the polymer was again collected by filtration and vacuum dried at 100 ° C. The obtained polymer was dissolved in CH ₂ Cl ₂ (10 ml), then dropped into methanol (300 ml), and precipitated again. The polymer was collected by filtration and dried in vacuo at 60 ° C. to obtain 1.9 g (Mn = 33000) of a copolymer.

1 g of the copolymer obtained above was dissolved in CH ₂ Cl ₂ (15 ml), chlorosulfonic acid (0.5 ml) was added dropwise, and the mixture was stirred at room temperature for 8 hours. The solid was separated by filtration, immersed in ion-exchanged water, stirred and filtered repeatedly and washed until the washing water became neutral. The solid was filtered off and vacuum dried at 100 ° C. for 24 hours to obtain a yellow solid (1 g) as a polymer electrolyte.

  After dissolving this in NMP, the solution was cast on a glass plate, dried by ventilation at 55 ° C. for 15 hours, and then further vacuum dried at 120 ° C. for 18 hours. The ion exchange capacity of this membrane was 1.58 meq / g.

  The polymer electrolyte membrane was evaluated in the same manner as in Example 1. The results are shown in Tables 1-3.

[Comparative Example 1]
<Preparation of sulfonated polyphenylene sulfide polymer electrolyte membrane>
Pellets of polyphenylene sulfide (Dainippon Ink Industries, Ltd., DIC-PPS LD10p11) were mixed with a twin-screw extruder with a T-die set in a twin-screw kneading extruder under a screw temperature of 290 ° C and a T-die temperature of 290 ° C. The polymer film was obtained by melt extrusion molding. A glass container was weighed with 634 g of 1-chlorobutane and 15 g of chlorosulfonic acid to prepare a chlorosulfonic acid solution. 1.5 g of the polymer film was weighed and immersed in the chlorosulfonic acid solution at 25 ° C. for 20 hours (the amount of chlorosulfonic acid added was 10 times the weight of the polymer film). Thereafter, the polymer film was recovered and washed with ion exchange water until neutral.

  The polymer electrolyte membrane was evaluated in the same manner as in Example 1. The results are shown in Tables 1-3.

[Comparative Example 2]
Pellets of polyphenylene sulfide (Dainippon Ink Industries, Ltd., DIC-PPS LD10p11) were mixed with a twin-screw extruder with a T-die set in a twin-screw kneading extruder under a screw temperature of 290 ° C and a T-die temperature of 290 ° C. The polymer film was obtained by melt extrusion molding. A glass container was weighed with 634 g of 1-chlorobutane and 15 g of chlorosulfonic acid to prepare a chlorosulfonic acid solution. 1.5 g of the polymer film was weighed and immersed in the chlorosulfonic acid solution at 25 ° C. for 20 hours (the amount of chlorosulfonic acid added was 10 times the weight of the polymer film). Thereafter, the polymer film was recovered and washed with ion exchange water until neutral.

  The polymer electrolyte membrane was evaluated in the same manner as in Example 1. The results are shown in Tables 1-3.

[Comparative Example 3]
Pellets of polyphenylene sulfide (Dainippon Ink Industries, Ltd., DIC-PPS LD10p11) were mixed with a twin-screw extruder with a T-die set in a twin-screw kneading extruder under a screw temperature of 290 ° C and a T-die temperature of 290 ° C. The polymer film was obtained by melt extrusion molding. A glass container was weighed with 634 g of 1-chlorobutane and 15 g of chlorosulfonic acid to prepare a chlorosulfonic acid solution. 1.5 g of the polymer film was weighed and immersed in the chlorosulfonic acid solution at 25 ° C. for 20 hours (the amount of chlorosulfonic acid added was 10 times the weight of the polymer film). Thereafter, the polymer film was recovered and washed with ion exchange water until neutral.

  The polymer electrolyte membrane was evaluated in the same manner as in Example 1. The results are shown in Tables 1-3.

  Table 1 shows the weight% of antifreeze water, ion exchange capacity, and λ (antifreeze water) value.

  Table 2 shows proton conductivities at 23 ° C., 30% RH and 95% RH. In Comparative Example 2 and Comparative Example 3, the membrane resistivity was high and proton conductivity could not be measured.

  Table 3 shows the proton conductivity at 85 ° C. and 30% RH and 95% RH. In Comparative Example 2 and Comparative Example 3, the membrane resistivity was high and proton conductivity could not be measured.

[Conclusion]
When the samples of Examples 1, 2 and Comparative Example 1 having approximately the same proton conductivity at high humidity are compared at low humidity, it can be seen that Examples 1 and 2 are superior. In addition, comparing Example 1, Example 2, and Comparative Example 2 having similar ion exchange capacities, the proton conductivity of Example 1 and Example 2 is excellent even at high humidity, and the difference is remarkable at low humidity. I know that there is. In Examples 1, 2 and Comparative Example 1, the weight percentage of the antifreeze water is almost the same, and the proton conductivity at high humidity is almost the same and excellent. However, the proton conductivity at low humidity is excellent. Example 1 and Example 2 are excellent. This indicates that the relationship between the weight percent of antifreeze water in the polymer electrolyte membrane and the ion exchange capacity is important. Therefore, relational expression 1 represents the relationship between the number of water molecules present as antifreeze water and the number of ion exchange groups. This is thought to be due to the surrounding environment of water molecules present as antifreeze water in the polymer electrolyte membrane.

[Relational expression 1]
25.00> λ (non-freezing water)> 1.00
(However, λ (antifreeze water) is the number of water molecules present as antifreeze water divided by the number of ion exchange groups.)

Structural drawing of the cross section of the main part of a polymer electrolyte fuel cell using the polymer electrolyte membrane of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2 Catalyst layer 3 Diffusion layer 4 Separator 5 Channel 10 Solid polymer fuel cell 15 Oxidant channel 16 Membrane / electrode assembly (MEA)
17 Fuel Tank 18 Fuel Filling Portion 19 Support 20 Direct Methanol Fuel Cell

Claims (10)

The ratio of the number of water molecules present in the polymer electrolyte as antifreeze water to the number of ion-exchange groups λ (antifreeze water) in the water-containing state satisfies the relational expression 1; Molecular electrolyte.
[Relational expression 1]
25.00> λ (non-freezing water)> 1.00
(However, λ (antifreeze water) is the number of water molecules present as antifreeze water divided by the number of ion exchange groups.) The polymer electrolyte according to claim 1, wherein the polymer electrolyte is obtained by sulfonating a polymer having at least one structure selected from the group consisting of the following formulas (1) to (4).

(Wherein X ¹ is a linking group or a direct bond selected from —O—, —S—, —NH—, —CO—, —SO ₂ —, and Ar ¹ has 0 to 4 substituents. A hydrocarbon-based aromatic ring or an aromatic heterocycle containing any one of oxygen, sulfur, and nitrogen, and the substituent for Ar ¹ has an alkyl group, an alkoxy group, or a substituent. And when there are a plurality of aryl groups having 6 to 30 carbon atoms, ketone groups, sulfone groups, fluorine, chlorine and bromine, they may be the same or different, and n represents an integer.)

(Wherein, X ¹ and Ar ¹ are the same as described above. X ² is a linking group selected from —O—, —S—, —NH—, —CO— and —SO ₂ — or a direct bond. Ar ² has 0 to 4 substituents, a hydrocarbon aromatic ring or oxygen, sulfur, Examples of the substituent of .Ar ² is aromatic heterocycle containing any atom of the nitrogen group , An alkoxy group, an optionally substituted aryl group having 6 to 30 carbon atoms, a ketone group, a sulfone group, fluorine, chlorine and bromine, which may be the same as or different from each other. Good, n represents an integer.)

(Wherein X ¹ , X ² , Ar ¹ and Ar ² are the same as described above. X ³ is a linking group selected from —O—, —S—, —NH—, —CO— and —SO ₂ —. Alternatively .Ar ³ is a direct bond has 0 to 4 substituents, a hydrocarbon aromatic ring or oxygen, sulfur, the .Ar ³ is aromatic heterocycle containing any atom of the nitrogen The substituent is an alkyl group, an alkoxy group, an aryl group having 6 to 30 carbon atoms which may have a substituent, a ketone group, a sulfone group, fluorine, chlorine, or bromine. Or n may be different. N represents an integer.)

(Wherein X ¹ , X ² , X ³ , Ar ¹ , Ar ² , Ar ³ are the same as described above. X ⁴ is —O—, —S—, —NH—, —CO—, —SO _2. Ar ⁴ is a hydrocarbon aromatic ring having 0 to 4 substituents or an aromatic hetero ring containing any one of oxygen, sulfur, and nitrogen atoms. Ar ⁴ substituents are alkyl groups, alkoxy groups, optionally substituted aryl groups having 6 to 30 carbon atoms, ketone groups, sulfone groups, fluorine, chlorine, bromine, and a plurality of them. In this case, they may be the same or different from each other, and n represents an integer.)   The polymer electrolyte according to claim 1, wherein the polymer electrolyte has a hydrophilic segment and a hydrophobic segment in the same molecule.   The polymer electrolyte according to any one of claims 1 to 3, wherein the hydrophilic segment has an ion exchange capacity of 1.0 to 8.5 meq / g.   3. The polymer electrolyte according to claim 1, wherein the polymer electrolyte is a polymer composed of two or more types of monomers, and has a portion where the amount of sulfonic acid group introduced per minimum repeating unit of the polymer is different.   The polymer electrolyte according to claim 5, which has an ion exchange capacity of 1.0 to 8.5 meq / g.   The polymer electrolyte membrane containing the polymer electrolyte as described in any one of Claims 1-6.   A membrane electrode assembly comprising the polymer electrolyte membrane according to claim 7.   A solid polymer fuel cell comprising the polymer electrolyte membrane according to claim 7.   A polymer electrolyte fuel cell comprising the membrane electrode assembly according to claim 8.

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