JP5669170B2 - Polymer electrolyte, polymer electrolyte membrane, and use thereof - Google Patents

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. In addition, 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.

  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)) is illustrated. However, in this document, it has been shown that when the IEC is 2.6 meq / g or more, it is dissolved in water and cannot be used as an electrolyte membrane for a fuel cell.

  Patent Document 1 exemplifies a homopolymer and a random copolymer containing a benzonitrile structure, but in an electrolyte membrane using a random copolymer or a homopolymer, a microphase separation state effective for proton conductivity at low humidity It is known that it is difficult to become.

  Patent Document 2 exemplifies a block copolymer, but both the hydrophilic part and the hydrophobic part to be used must be synthesized by another synthesis method, and in the polymerization of the polyparaphenylene-based unit used. Since the monomers that can be used to suppress side reactions are limited, synthesis other than those exemplified is difficult. There is a disadvantage that it is necessary to go through a complicated manufacturing process and is very expensive.

JP 2004-244437 A JP 2001-250567 A

New Materials For Fuel Cell And Modern Battery Systems II 794-785

  An object of the present invention is to provide a hydrocarbon polymer electrolyte having excellent processability and proton conductivity, particularly excellent proton conductivity in a low water content, and a membrane thereof.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that in a block copolymer comprising a unit having a high sulfonic acid group introduction rate and a unit having a low sulfonic acid group introduction rate, It was discovered that when the density of a partial sulfonic acid group is increased by giving a bent unit main chain structure to a high unit, the desired proton conductivity can be exhibited in a low moisture state, and the present invention has been completed. .

  That is, the present invention is a block copolymer including a unit having a high sulfonic acid group introduction rate and a unit having a low sulfonic acid group introduction rate, and has a structure represented by the following formula (1) as a unit having a high sulfonic acid group introduction rate. It is a polymer electrolyte having a structure in which a sulfonic acid group is introduced in the main chain.

(Ar ¹ , Ar ² , and Ar ³ each represents an optionally substituted benzene ring, naphthalene ring or nitrogen-containing heteroaromatic ring, provided that at least one of Ar ^{1 to} Ar ³ is a para-ring. X ¹ represents O, a direct bond or fluorenylidene, and a is 0 to 4.)
It is preferable that at least one of Ar ¹ , Ar ² , and Ar ³ in the above formula (1) is the following formula (2), (3), (4), or (5).

(R ¹ is fluorine, chlorine, bromine, cyano group, nitro group, C 1-10 alkyl group which may be fluorinated, C 6-12 aryl group, C 1-9 and nitrogen. A heteroaromatic ring, an alkoxy group having 1 to 10 carbon atoms, COZ, or SO ₂ Z, wherein Z is an optionally substituted alkyl group having 1 to 10 carbon atoms, or an optionally substituted carbon An aryl group having a number of 6 to 12. In some cases, they may be the same or different, and b represents an integer of 0 to 4.

(R ¹ is the same as above. B is the same as above.)

(R ¹ is the same as above. C represents an integer of 0 to 6. However, the binding sites are limited to sites that are not para to each other.)

(However, the binding sites are limited to sites that are not para to each other.)
It is preferable that at least one of Ar ¹ , Ar ² , and Ar ³ in the above formula (1) has a structure represented by the following formula (6).

(However, the binding sites are limited to sites that are not para to each other.)
It is preferable that the unit having a high introduction rate of the sulfonic acid group includes a structure represented by the following formula (7) and / or (8).

(X ¹ is the same as above. R ² is fluorine, chlorine, bromine, an optionally fluorinated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, and nitrogen having 1 to 9 carbon atoms. A heteroaromatic ring to be included, or an alkoxy group having 1 to 10 carbon atoms, and in some cases, they may be the same or different, and in some cases, they may be the same or different. the same as.)

(X ¹ is the same as above. R ² is the same as above. A and c are the same as above.)
It is preferable that the unit having a low introduction rate of the sulfonic acid group includes a structure represented by the following structural formula (9).

(X ² represents CO or SO _2. R ³ represents an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, a cyano group, COZ or SO ₂ Z, and Z represents a substituent. And an alkyl group having 1 to 10 carbon atoms and an aryl group having 6 to 12 carbon atoms, which may be the same or different from each other, d is a value from 0 to 4, and Y is Represents hydrogen, metal ion, or ammonium ion, and e represents 0 to 2. However, when a is 1, the sum of e is less than 2.
The unit having a low introduction rate of the sulfonic acid group preferably includes a structure represented by the following formula (10).

(X ¹ and X ² are the same as above.)
The polymer electrolyte membrane of the present invention includes the polymer electrolyte.

  The membrane electrode assembly of the present invention includes the polymer electrolyte membrane.

  The polymer electrolyte fuel cell of the present invention includes the polymer electrolyte membrane and / or the membrane electrode assembly.

  ADVANTAGE OF THE INVENTION According to this invention, the polymer electrolyte which is excellent in workability and has proton conductivity, especially the proton conductivity excellent in the condition with little water | moisture content can be provided.

1 is a structural view of a cross section of a main part of a polymer electrolyte fuel cell using a polymer electrolyte membrane of the present invention.

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

<Polymer electrolyte according to the present invention>
The polymer electrolyte of the present invention is a block copolymer composed of units having a high sulfonic acid group introduction rate and units having a low sulfonic acid group introduction rate. Here, the block copolymer refers to a unit in which units having different properties are bonded to each other and has a property different from that of a homopolymer comprising the original unit. A unit refers to a site having a structure that can be regarded as a continuous and identical composition.

  The polymer electrolyte of the present invention has a main chain in which a sulfonic acid group is introduced into a bent structure represented by the following formula (1) as a unit having a high sulfonic acid group introduction rate. The partial sulfonic acid group density is increased.

(Ar ¹ , Ar ² , and Ar ³ each represents an optionally substituted benzene ring, naphthalene ring or nitrogen-containing heteroaromatic ring, provided that at least one of Ar ^{1 to} Ar ³ is a para-ring. X ¹ represents O, a direct bond or fluorenylidene, and a is 0 to 4.)
More specifically, the following (2) and (3) are preferable as the benzene ring bonded at a non-para site.

(R ¹ is fluorine, chlorine, bromine, cyano group, nitro group, C 1-10 alkyl group which may be fluorinated, C 6-12 aryl group, C 1-9 and nitrogen. A heteroaromatic ring, an alkoxy group having 1 to 10 carbon atoms, COZ, or SO ₂ Z, wherein Z is an optionally substituted alkyl group having 1 to 10 carbon atoms, or an optionally substituted carbon An aryl group having a number of 6 to 12. In some cases, they may be the same or different, and b represents an integer of 0 to 4.

(R ¹ is the same as above. B is the same as above.)
From the viewpoint of improving workability, it is preferable that at least one structure represented by the following formula (6) is included.

(However, the binding sites are limited to sites that are not para to each other.)
As a naphthalene ring, the structure shown by following formula (4) is preferable.

(R ¹ is the same as above. C represents an integer of 0 to 6. However, the binding sites are limited to sites that are not para to each other.)
In addition, that the naphthalene ring is bonded at a non-para site means that the bonded sites are not 1- and 4-positions, specifically, 1,2-position, 1,3-position, 1,5-position of the naphthalene ring. , 1, 6 position, 1, 7 position, 1, 8 position, 2, 3 position, 2, 6 position, 2, 7 position. From the viewpoint of obtaining raw materials, those bonded at the 1st, 2nd, 1st, 5th, 1st, 6th, 1st, 7th, 1st, 8th, 2nd and 6th positions are preferable.

  As the heteroaromatic ring containing nitrogen bonded at a non-para site, a structure represented by the following formula (5) is preferable.

(However, the binding sites are limited to sites that are not para to each other.)
In the formula (1), it is preferable that at least one of the above formulas (2) to (5) is contained. When a plurality of the above chemical formulas (2) to (5) are contained, they may be the same or different.

  In the polymer electrolyte of the present invention, the unit having a high sulfonic acid group introduction rate preferably includes a structure represented by the following formula (7) and / or (8).

(X ¹ is the same as above. R ² is fluorine, chlorine, bromine, an optionally fluorinated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, and nitrogen having 1 to 9 carbon atoms. A heteroaromatic ring to be included, or an alkoxy group having 1 to 10 carbon atoms, and in some cases, they may be the same or different, and in some cases, they may be the same or different. the same as.)

(X ¹ is the same as above. R ² is the same as above. A and c are the same as above.)
From the viewpoint of improving workability, it is preferable that at least one of the benzene ring or naphthalene ring in the above formulas (7) and (8) is bonded at a site that is not para.

  The unit having a low introduction rate of sulfonic acid group preferably has a large number of aromatic rings bonded to an electron-withdrawing functional group or a large number of aromatic rings having a substituent. It is preferable to have one or more electron-withdrawing functional groups or one or more substituents. Specifically, from the viewpoint of chemical stability, the structure represented by the formula (9) is preferably included.

(X ² represents CO or SO _2. R ³ represents an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, a cyano group, COZ or SO ₂ Z, and Z has a substituent. An alkyl group having 1 to 10 carbon atoms and an aryl group having 6 to 12 carbon atoms, which may be the same or different from each other, d is a value from 0 to 4, and Y is hydrogen. Represents a metal ion or an ammonium ion, and e represents 0 to 2. However, when a is 1, the sum of e is a value less than 2.
Especially, it is preferable that the structure shown by Formula (10) is included from a viewpoint of workability.

(X ¹ and X ² are the same as above.)
In the present invention, the high introduction rate of the sulfonic acid group is not particularly limited, but the total aromatic ring contained in the unit preferably has 25% or more of the sulfonic acid group, and 40% or more. It is more preferable that it is 60% or more. On the other hand, the low introduction rate of the sulfonic acid group means that the total aromatic ring contained in the unit is preferably less than 25%, more preferably less than 20%, and less than 15%. More preferably.

  The unit having a high sulfonic acid group introduction rate and the unit having a low sulfonic acid group introduction rate each preferably have a number average molecular weight of 200 or more, more preferably 1000 or more, and still more preferably 2000 or more.

<Method for producing polymer electrolyte>
There are mainly two methods for producing the polymer electrolyte of the present invention, and any method can be used.

  The first production method is a method in which a unit precursor or a block copolymer is produced and then converted into a sulfonic acid group. However, the unit precursor or block copolymer here is a monomer or oligomer having a sulfonic acid group or a sulfur-containing site such as a sulfide bond, a sulfoxide bond or a sulfone bond that can be converted into a sulfonic acid group by oxidation treatment or the like. Or a polymer and any of these sulfonic acid group derivatives.

  The second production method is a method in which a sulfonic acid group is introduced by a sulfonation reaction after producing a unit precursor or a block copolymer having many aromatic rings having no electron withdrawing group. Among these, from the viewpoint of simplifying the production process, it is preferable to form a unit having a high introduction rate of sulfonic acid groups by sulfonation after the block copolymer is produced.

  Here, a method for producing a polymer electrolyte by the second production method will be described.

(Synthesis method of unit precursor)
Various methods can be used for synthesizing each unit precursor, such as general polymerization methods (for example, “New Polymer Experimental 3 Polymer Synthesis Method / Reaction (2) Condensation Polymer Synthesis” p. 7-57, p.399-401, (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.

  As a preferable polymerization reaction, a polycondensation reaction between a dihalide and a diol having a phenolic hydroxyl group is exemplified. Each of these monomers may be used alone or in combination of two or more.

  Monomers that can be used when synthesizing units having a high introduction rate of sulfonic acid groups include diols having a benzene ring, hydroquinone, resorcinol, catechol, 2,2-bis (4-hydroxyphenyl) propane, 2,2 -Bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (2-hydroxy-5-biphenylyl) propane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2, 3-dihydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,5-dihydroxybenzophenone, 3,4-dihydroxybenzophenone, 3,5-dihydroxybenzophenone, 2,2'-dihydroxybenzophenone, 2,3'-dihydroxybenzophenone, 2, , 4'-dihydroxy Benzophenone, 3,3′-dihydroxybenzophenone, 3,4′-dihydroxybenzophenone, 4,4′-dihydroxybenzophenone, 2,3-dihydroxydiphenylsulfone, 2,4-dihydroxydiphenylsulfone, 2,5-dihydroxydiphenylsulfone, 3,4-dihydroxydiphenylsulfone, 3,5-dihydroxydiphenylsulfone, 2,2'-dihydroxydiphenylsulfone, 2,3'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 3,3'-dihydroxydiphenyl Sulfone, 3,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 2,3-dihydroxybiphenyl, 2,4-dihydroxybiphenyl, 2,5-dihydroxybiff Nyl, 3,4-dihydroxybiphenyl, 3,5-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 2,3'-dihydroxybiphenyl, 2,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3, 4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-phenylphenyl) fluorene, 9,9-bis ( 4-hydroxy-3,5-diphenylphenyl) fluorene and derivatives thereof. The benzene ring may have a substituent, and examples of the substituent include hydrogen, an alkyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or one of these. A part or all of which is substituted with fluorine is exemplified. From the viewpoint of chemical stability, hydrogen, an aryl group, or an alkyl group in which all are substituted with fluorine are preferable.

  As dihalides having a benzene ring, 2,3-difluorobenzonitrile, 2,4-difluorobenzonitrile, 2,5-difluorobenzonitrile, 2,6-difluorobenzonitrile, 2,3-dichlorobenzonitrile, 2,4 -Dichlorobenzonitrile, 2,5-dichlorobenzonitrile, 2,6-dichlorobenzonitrile and derivatives thereof. The benzene ring may have a substituent, and examples of the substituent include hydrogen, an alkyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or one of these. A part or all of which is substituted with fluorine is exemplified. From the viewpoint of chemical stability, hydrogen, an aryl group, or an alkyl group in which all are substituted with fluorine are preferable.

  Diols having a naphthalene ring include 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1 , 8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,1′-bi-2-naphthol, 1,1′-bi-3-naphthol, 1 , 1'-bi-4-naphthol, 1,1'-bi-5-naphthol, 1,1'-bi-6-naphthol, 1,1'-bi-7-naphthol, 1,1'-bi 8-naphthol, 2,2'-bi-1-naphthol, 2,2'-bi-3-naphthol, 2,2'-bi-4-naphthol, 2,2'-bi-5-na Examples include phthal, 2,2'-bi-6-naphthol, 2,2'-bi-7-naphthol, 2,2'-bi-8-naphthol, and derivatives thereof. The naphthalene ring may have a substituent, such as hydrogen, an alkyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or one of these. A part or all of which is substituted with fluorine is exemplified. From the viewpoint of chemical stability, hydrogen, an aryl group, or an alkyl group in which all are substituted with fluorine are preferable.

  Examples of the diol having a nitrogen-containing heteroaromatic ring include 2,3-dihydroxypyridine, 2,4-dihydroxypyridine, 2,5-dihydroxypyridine, and 2,6-dihydroxypyridine. The heteroaromatic ring containing nitrogen may have a substituent, such as hydrogen, an alkyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, Alternatively, those in which part or all of these are substituted with fluorine are exemplified.

As dihalides having a heteroaromatic ring containing nitrogen, 2,3-difluoropyridine, 2,4-difluoropyridine, 2,5-difluoropyridine, 2,6-difluoropyridine, 2,3-dichloropyridine, 2,4- Examples include dichloropyridine, 2,5-dichloropyridine, and 2,6-dichloropyridine. The heteroaromatic ring containing nitrogen may have a substituent, such as hydrogen, an alkyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, Alternatively, those in which part or all of these are substituted with fluorine are exemplified.
In order to have a bent structure, it is necessary that at least one is bonded at a non-para site in formula (1), but a structure in which all are bonded at a non-para site is preferable.

  Examples of diols having a benzene ring bonded at a non-para site include resorcinol, catechol, 2,2-bis (2-hydroxy-5-biphenylyl) propane, 2,3-dihydroxybenzophenone, and 2,4-dihydroxybenzophenone. 3,4-dihydroxybenzophenone, 3,5-dihydroxybenzophenone, 2,2'-dihydroxybenzophenone, 2,3'-dihydroxybenzophenone, 2,4'-dihydroxybenzophenone, 3,3'-dihydroxybenzophenone, 3,4 '-Dihydroxybenzophenone, 2,3-dihydroxydiphenylsulfone, 2,4-dihydroxydiphenylsulfone, 3,4-dihydroxydiphenylsulfone, 3,5-dihydroxydiphenylsulfone, 2,2'-dihydroxydiph Nyl sulfone, 2,3′-dihydroxydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, 3,3′-dihydroxydiphenyl sulfone, 3,4′-dihydroxydiphenyl sulfone, 2,3-dihydroxybiphenyl, 2,4-dihydroxy Biphenyl, 3,4-dihydroxybiphenyl, 3,5-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 2,3'-dihydroxybiphenyl, 2,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3, Examples thereof include 4'-dihydroxybiphenyl and derivatives thereof. Of these, 3,5-dihydroxybiphenyl, 2,2′-dihydroxybiphenyl, and 2,4′-dihydroxybiphenyl are preferable.

  Examples of the dihalide having a benzene ring bonded at a non-para site include 2,3-difluorobenzonitrile, 2,4-difluorobenzonitrile, 2,6-difluorobenzonitrile, 2,3-dichlorobenzonitrile, 2, Examples include 4-dichlorobenzonitrile, 2,6-dichlorobenzonitrile and derivatives thereof. Of these, 2,4-difluorobenzonitrile, 2,6-difluorobenzonitrile, 2,4-dichlorobenzonitrile, and 2,6-dichlorobenzonitrile are preferable.

  The heteroaromatic ring containing nitrogen bonded at a non-para site includes 2,4-difluoropyridine, 2,6-difluoropyridine, 2,4-dichloropyridine, and 2,6-dichloropyridine from the viewpoint of obtaining raw materials. Is preferred.

  For the synthesis of a unit precursor having a low introduction rate of sulfonic acid group, a dihalide that can be used for the production of a unit having a high introduction rate of sulfonic acid group can be used as a dihalide. In addition, 4,4′-difluorobenzophenone, 4 4,4′-dichlorobenzophenone, 4,4′-difluorodiphenyl sulfone, 4,4′-dichlorodiphenyl sulfone, or structural isomers thereof. An aromatic compound, an aromatic carbonyl compound, an aromatic sulfonyl compound, an aromatic nitrile compound, an aromatic nitro compound, or an aromatic fluoroalkyl compound having two or more halogen substituents on the aromatic ring can also be used.

As the diol, a diol that can be used for the synthesis of a unit precursor having a high sulfonic acid group introduction rate can be used. Among them, from the viewpoint of adjusting the sulfonic acid group introduction rate,
Hydroquinone, resorcinol, catechol, or those containing an electron withdrawing group are preferred.

  In the polycondensation reaction, one or more bases such as metal carbonates such as potassium carbonate, sodium carbonate and calcium carbonate, and metal hydroxides such as potassium hydroxide and sodium hydroxide can be used.

  The solvent is not particularly limited as long as polymerization is not prohibited, and examples thereof include heterocyclic compounds (3-methyl-2-oxazolidinone, 1-methyl-2-pyrrolidone (hereinafter abbreviated as NMP), 1,3-dimethyl. -2-imidazolidinone (hereinafter abbreviated as DMI)), cyclic ethers (dioxane, tetrahydrofuran, etc.), chain ethers (diethyl ether, ethylene glycol dialkyl ether, etc.), nitrile compounds (acetonitrile, glutarodinitrile, Methoxyacetonitrile, etc.), aprotic polar substances (dimethyl sulfoxide (hereinafter abbreviated as DMSO), sulfolane, dimethylformamide (hereinafter abbreviated as DMF), dimethylacetamide (hereinafter abbreviated as DMAc)), nonpolar solvents (hexane, cyclohexane, Benzene, toluene, xyle Etc.), halogenated solvents (chlorobenzene, 1,2-dichlorobenzene, etc.), water and the like can be enumerated. From the viewpoint of solubility, heterocyclic compounds such as DMI and NMP and aprotic polar substances such as DMSO, DMF, and DMAc are preferable because of high polymer solubility. Among these, DMI, DMSO, DMF, and DMAc are particularly preferable because of high polymer solubility. These may be used alone or in combination of two or more. Further, a solvent such as cyclohexane or toluene may be used together to remove water generated by polymerization from the system.

  The reaction temperature can be appropriately set according to the reactivity and stability of the monomer used in the polymerization reaction, preferably 20 ° C to 300 ° C, more preferably 40 ° C to 250 ° C, and even more preferably 70 ° C. ~ 240 ° C. If the temperature is lower than this range, the reaction rate tends to be remarkably reduced. On the other hand, 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. The polymer produced after the polymerization reaction step may be taken out. Further purification steps may be added.

  By changing the molar ratio of dihalide and diol having phenolic hydroxyl groups, it is possible to produce halogen-terminated polymers with halogens at both ends, or phenolic hydroxyl-terminated polymers with phenolic hydroxyl groups at both ends. it can.

(Manufacture of block copolymer)
A unit precursor having a high sulfonic acid group introduction rate and a unit precursor having a low sulfonic acid group introduction rate can be synthesized by a polycondensation reaction, and the polymerization conditions and the like can be performed under the same conditions as described above. One of the unit precursors is terminated with a phenolic hydroxyl group and the other unit precursor is terminated with a halogen, and a block copolymer can be obtained by a polycondensation reaction. Any of the unit precursors may be terminated with a phenolic hydroxyl group, and these unit precursors may be linked using a linking agent to obtain a block copolymer. As the linking group, a divalent or trivalent linking group, or a polyvalent linking group such as decafluorobiphenyl can be used. Any of the unit precursors may be halogen-terminated, and a diol may be used to link these unit precursors to obtain a block copolymer. As the diol, the above-mentioned diols can be similarly applied.

  In order to simplify the synthesis process, one of the unit precursors may be synthesized in advance, a monomer may be added to the reaction vessel, the other unit may be synthesized, and a block copolymer may be synthesized.

(Introduction of sulfonic acid group)
The introduction of the sulfonic acid group may be before the synthesis of the block copolymer or after the synthesis of the block copolymer.

  Examples of the sulfonating agent include sulfuric acid, chlorosulfonic acid, fuming sulfuric acid and the like. Among these, sulfuric acid and chlorosulfonic acid are preferable because they have appropriate reactivity.

  The solvent is not particularly limited as long as it does not inhibit the reaction, and cyclic ethers (dioxane, tetrahydrofuran, etc.), chain ethers (diethyl ether, ethylene glycol dialkyl ether, etc.), nonpolar solvents (toluene, xylene, etc.) Listed are chlorinated solvents (methylene chloride, 1,2-dichloroethane, ethylene chloride, etc.), sulfonic acids (methanesulfonic acid, trifluoromethanesulfonic acid, etc.), sulfuric acid, and water. Of these, chlorinated solvents such as methylene chloride and 1,2-dichloroethane are preferred from the viewpoint of solubility. These may be used alone or in combination of two or more.

  What is necessary is just to set reaction temperature suitably according to reaction, Specifically, it is preferable to set to -80 degreeC-200 degreeC which is the optimal use range of a sulfonating agent, -50 degreeC-160 degreeC is more preferable,- 20 to 140 ° C. is more preferable. If the temperature is lower than this range, the reaction tends to be slow, and if the temperature is high, a rapid reaction occurs and sulfonation may progress to other than the intended site.

<Polymer electrolyte membrane>
The polymer electrolyte of the present invention can be used alone or in the form of a complex containing other components and formed into a membrane to be used as a polymer electrolyte membrane.

  As a film forming method, a known method can be appropriately used. For example, 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, or an emulsion method can be exemplified. For example, there is a method in which a polymer electrolyte is put into an extruder in which a T die is set, and film formation is performed while melt kneading. It is also possible to perform the composite in the film forming process. In the case of the casting method, 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 form a membrane. Can be obtained. 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.

  In order to control the molecular orientation of the polymer electrolyte membrane, the obtained polymer electrolyte membrane may be subjected to a treatment such as biaxial stretching or a heat treatment for controlling the crystallinity. . In order to improve the mechanical strength of the polymer electrolyte membrane, various fillers may be added, or a reinforcing agent such as a glass nonwoven fabric and the polymer electrolyte membrane may be combined by pressing.

  As the thickness of the polymer electrolyte membrane, any thickness can be selected according to 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 above range, handling is improved, such as easy handling and less damage. The proton conductivity of the polymer electrolyte membrane can also be expressed within a desired range.

  It is also possible to introduce a sulfonic acid group after forming a polymer electrolyte membrane. 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 properties 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.

<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.

<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.

  The measurement methods of the molecular weight of the polymer, the ion exchange capacity of the polymer electrolyte, and the proton conductivity are as follows.

[Measurement method of molecular weight]
The molecular weight was measured by GPC method. The conditions are as follows.

GPC measuring device HLC-8220 manufactured by TOSOH
Two columns, Super AW 4000 and Super AW 2500, manufactured by SHOWA DENKO, are connected in series. Column temperature 40 ° C
Mobile phase solvent NMP (LiBr added to 10 mmol / dm ³ )
Solvent flow rate 0.3 mL / min
[Measurement method of ion exchange capacity (hereinafter abbreviated as IEC)]
The target polymer electrolyte (about 100 mg: sufficiently dried) was immersed in 20 mL of a saturated aqueous sodium chloride solution at 25 ° C., and subjected to an ion exchange reaction in a water bath at 60 ° C. for 3 hours. After cooling to 25 ° C., the membrane was thoroughly washed with ion exchanged water, and all of the saturated aqueous sodium chloride solution and the washing water were collected. To this collected solution, a phenolphthalein solution was added as an indicator, and neutralization titration was performed with a 0.01N sodium hydroxide aqueous solution to calculate IEC.

[Measurement method of proton conductivity]
Proton conductivity measurement is performed using a constant temperature and humidity chamber (manufactured by ESPEC, SH-221), keeping the temperature and humidity constant (about 3 hours), and using an impedance analyzer (manufactured by Hioki, 3532-50) The resistance of was measured. Specifically, the frequency response from 50 kHz to 5 MHz was measured with an impedance analyzer, and the proton conductivity was calculated from the following equation.
Proton conductivity (S / cm) = D / (W × T × R)
Here, D is a distance between electrodes (cm), W is a film width (cm), T is a film thickness (cm), and R is a measured resistance value (Ω). In this measurement, D = 1 cm and W = 1 cm, and the film thickness was a value measured using a micrometer for each sample. The temperature and humidity were 85 ° C. and 30% RH, respectively.

[Synthesis Example 1]
12.4 g of 4,4′-difluorodiphenylsulfone, 10.2 g of 4,4′-dihydroxybenzophenone, 8.6 g of potassium carbonate, 50 ml of DMAc and 15 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 8 hours, the reaction solution was added to water after cooling to room temperature, and the precipitated polymer was finely pulverized with a mixer, filtered and dried to obtain a polymer (hereinafter referred to as P1). The molecular weight of the obtained P1 was Mn = 44000.

  Further, this P1 was dissolved in 100 g of 2 g dichloromethane, and sulfonation was carried out by adding 10 ml of chlorosulfonic acid. The IEC was 0.05 meq / g. The sulfonic acid group introduction rate was 0.01%.

[Synthesis Example 2]
In Synthesis Example 1, 3.0 g of 2,6-difluorobenzonitrile and 4.2 g of 2,2′-dihydroxybiphenyl were used in place of 4,4′-difluorodiphenylsulfone and 4,4′-dihydroxybenzophenone. Were synthesized in the same manner to obtain a white polymer (hereinafter referred to as P2). The molecular weight of the obtained P2 was Mn = 10000. When P2 was sulfonated in the same manner as P1, IEC was 3.62 meq / g. The introduction rate of sulfonic acid group was 52%.

[Synthesis Example 3]
In Synthesis Example 1, instead of 4,4′-difluorodiphenyl sulfone and 4,4′-dihydroxybenzophenone, 3.0 g of 2,6-difluorobenzonitrile and 4.2 g of 4,4′-dihydroxybiphenyl and 2,2 A white polymer (hereinafter referred to as P3) was obtained in the same manner except that 4.2 g of '-dihydroxybiphenyl was used. The molecular weight of the obtained P3 was Mn = 11000. Further, when this P3 was sulfonated in the same manner as P1, the IEC was 3.48 meq / g. The introduction rate of sulfonic acid group was 46%.

[Synthesis Example 4]
In Synthesis Example 1, 2.6 g of 2,6-difluorobenzonitrile and 4,4 ′-(9-fluorenylidene) diphenol in place of 4,4′-difluorodiphenylsulfone and 4,4′-dihydroxybenzophenone A white polymer (hereinafter referred to as P4) was obtained in the same manner except that 0 g was used. The molecular weight of the obtained P4 was Mn = 8000. Further, when this P4 was sulfonated in the same manner as P1, the IEC was 4.03 meq / g. The introduction rate of sulfonic acid group was 53%.

[Synthesis Example 5]
In Synthesis Example 1, instead of 4,4′-difluorodiphenylsulfone and 4,4′-dihydroxybenzophenone, 7.1 g of 2,6-difluorobenzonitrile and 13.9 g of 1,1′-bi-2-naphthol were used. A white polymer (hereinafter referred to as P5) was obtained in the same manner except that it was used. The molecular weight of the obtained P5 was Mn = 13000. Further, when this P5 was sulfonated in the same manner as P1, the IEC was 2.88 meq / g. The sulfonic acid group introduction rate was 48%.

[Synthesis Example 6]
Synthesis was performed in the same manner as in Synthesis Example 1 except that 4.5 g of hydroquinone was used instead of 4,4′-dihydroxybenzophenone, and a white polymer was obtained (hereinafter referred to as P6). The molecular weight of P6 was Mn = 4400. Further, when this P6 was sulfonated in the same manner as P1, the IEC was 2.05 meq / g. The introduction rate of sulfonic acid group was 26%.

[Example 1]
1.14 g of 4,4′-difluorodiphenylsulfone, 1.00 g of 4,4′-dihydroxybenzophenone, 0.9 g of potassium carbonate, 5 ml of DMAc, and 2 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 1.5 hours, the mixture was cooled, 1.5 g of P2 was added, and the mixture was further reacted at 135 degrees for 7 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The mixture was pulverized with a mixer, filtered, washed with methanol, and then dried at 80 ° C. under reduced pressure. The molecular weight of the obtained polymer was Mn 58000. 3 g of the obtained polymer was dissolved in 100 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

  After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.70 meq / g. The proton conductivity measured under low humidification conditions was 3.2 × 10 ⁻⁴ S / cm.

[Example 2]
3.04 g of 4,4′-difluorodiphenylsulfone, 2.66 g of 4,4′-dihydroxybenzophenone, 2.2 g of potassium carbonate, 10 ml of DMAc and 4 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 1.5 hours, the mixture was cooled, 3.98 g of P3 was added, and further reacted at 135 degrees for 5 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The mixture was pulverized with a mixer, filtered, washed with methanol, and then dried at 80 ° C. under reduced pressure. The molecular weight of the obtained polymer was Mn79000. 3 g of the obtained polymer was dissolved in 60 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

  After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.63 meq / g. The proton conductivity measured under low humidification conditions was 3.5 × 10 ⁻⁴ S / cm.

Example 3
2.24 g of 4,4′-difluorodiphenylsulfone, 1.96 g of 4,4′-dihydroxybenzophenone, 1.6 g of potassium carbonate, 5 ml of DMAc, and 2 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 2 hours, the mixture was cooled, 1.85 g of P4 was added, and further reacted at 135 degrees for 3 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The mixture was pulverized with a mixer, filtered, washed with methanol, and then dried at 80 ° C. under reduced pressure. The molecular weight of the obtained polymer was Mn 56000. 5 g of the obtained polymer was dissolved in 200 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

  After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.55 meq / g. When proton conductivity was measured under low humidification conditions, it was 3.0 × 10 ⁻³ S / cm.

Example 4
1.68 g of 4,4′-difluorodiphenylsulfone, 1.47 g of 4,4′-dihydroxybenzophenone, 1.2 g of potassium carbonate, 5 ml of DMAc, and 2 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 2 hours, the mixture was cooled, 3.00 g of P4 was added, and further reacted at 135 degrees for 3 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The mixture was pulverized with a mixer, filtered, washed with methanol, and then dried at 80 ° C. under reduced pressure. The molecular weight of the obtained polymer was Mn 39000. 3 g of the obtained polymer was dissolved in 60 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

  After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.81 meq / g. The proton conductivity measured under low humidification conditions was 3.7 × 10 ⁻⁴ S / cm.

[Comparative Example 1]
In Synthesis Example 1, 10 g of a polymer (Mn = 47200) synthesized in the same manner except that 4.5 g of 4,4′-dihydroxydiphenyl sulfone was used instead of 4,4′-dihydroxybenzophenone in 30% fuming sulfuric acid. In addition, sulfonation was performed at 100 ° C. for 20 hours to obtain a polymer electrolyte. The obtained polymer electrolyte was added to a large amount of water, and filtered and washed with water. The obtained polymer electrolyte was easily soluble in water, and only 1.2 g was obtained.

  After dissolving 1 g of the washed polymer electrolyte 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. When it was peeled off, it melted when water was applied.

[Comparative Example 2]
In Synthesis Example 1, 6 g of a polymer (Mn = 47200) synthesized in the same manner as in Example 1 except that 4.5 g of 4,4′-dihydroxydiphenyl ether was used instead of 4,4′-dihydroxybenzophenone. Sulfonation gave a polymer electrolyte. After sulfonation, in addition to a large amount of water, filtration and washing with water were performed. The polymer electrolyte swelled severely by sucking water, but 5 g could be obtained.

  After 0.5 g of the obtained polymer electrolyte 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. When it was peeled from the board, it melted when water was applied.

[Comparative Example 3]
In Example 1, a polymer electrolyte was obtained in the same manner except that 1 g of P6 was used instead of P2.

  After dissolving 1 g of the obtained polymer electrolyte 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. It was easily peeled off when swollen and swollen. Again, it was vacuum-dried at 120 ° C. for 12 hours to obtain a self-supporting polymer electrolyte membrane.

  The obtained polymer electrolyte membrane had an ion exchange capacity of 1.63 meq / g. Under low humidification conditions, the membrane resistivity was high and proton conductivity could not be measured.

  From comparison between Examples 1 to 4 and Comparative Examples 1 and 2, it can be seen that the block copolymer (polymer electrolyte) of the present invention has good water resistance.

  From comparison between Examples 1 to 4 and Comparative Example 3, it can be seen that the block copolymer (polymer electrolyte) of the present invention exhibits excellent proton conductivity under low humidification conditions.

  Therefore, it was shown that the polymer electrolyte of the present invention is useful as a material for a solid polymer fuel cell, and particularly useful as a polymer electrolyte membrane.

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2 Catalyst layer 3 Diffusion layer 4 Separator 5 Flow path 10 Polymer electrolyte fuel cell

Claims (7)

A block copolymer including a unit having a sulfonic acid group introduction rate higher than a unit described later, and a unit having a lower sulfonic acid group introduction rate than the unit;
A unit having a high introduction rate of sulfonic acid group is represented by the following formula (1).

(Ar ¹ , Ar ² , and Ar ³ each represents an optionally substituted benzene ring, naphthalene ring or nitrogen-containing heteroaromatic ring. X ¹ represents O, a direct bond, or fluorenylidene, respectively. A is 0-4.)
Including a structure in which a sulfonic acid group is introduced in the structure represented by
When a = 0, at least one of Ar ¹ and Ar ² is represented, and when a = 1 to 4, at least one of Ar ¹ , Ar ² , and Ar ³ is represented by the following formula (6):

(However, the binding sites are limited to sites that are not para to each other.)
It is a structure shown by
A unit having a low sulfonic acid group introduction rate is represented by the following formula ( 10 ):

(X ¹ represents O, a direct bond or fluorenylidene, respectively, and X ² represents CO or SO _2. )
A polymer electrolyte comprising a structure represented by: At least one of Ar ¹ , Ar ² , and Ar ³ other than the structure represented by the formula (6) is represented by the following formula (2), (3), (4) or (5)

(R ¹ includes fluorine, chlorine, bromine, cyano group, nitro group, fluorinated which may be an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, the nitrogen at 1-9 carbon atoms heteroaromatic ring, alkoxy group having 1 to 10 carbon atoms, COZ or SO 2 shows a _Z, Z represents an alkyl group having 1 to 10 carbon atoms which may have a substituent, optionally with a substituent carbons, An aryl group having a number of 6 to 12. In some cases, they may be the same or different, and b represents an integer of 0 to 4.

(R ¹ includes fluorine, chlorine, bromine, cyano group, nitro group, fluorinated which may be an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, the nitrogen at 1-9 carbon atoms heteroaromatic ring, alkoxy group having 1 to 10 carbon atoms, COZ or SO 2 shows a _Z, Z represents an alkyl group having 1 to 10 carbon atoms which may have a substituent, optionally with a substituent carbons, An aryl group having a number of 6 to 12. In some cases, they may be the same or different, and b represents an integer of 0 to 4.

(R ¹ includes fluorine, chlorine, bromine, cyano group, nitro group, fluorinated which may be an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, the nitrogen at 1-9 carbon atoms heteroaromatic ring, alkoxy group having 1 to 10 carbon atoms, COZ or SO 2 shows a _Z, Z represents an alkyl group having 1 to 10 carbon atoms which may have a substituent, optionally with a substituent carbons, And an aryl group having a number of 6 to 12. In some cases, they may be the same or different, and c represents an integer of 0 to 6. However, the binding site is limited to the case where the position is not the 1st and 4th positions. )

(However, the binding sites are limited to sites that are not para to each other.)
The polymer electrolyte according to claim 1, wherein A unit having a high sulfonic acid group introduction rate is represented by the following formula (7) and / or (8):

(X ¹ represents O, a direct bond or fluorenylidene, respectively. R ² represents fluorine, chlorine, bromine, an optionally fluorinated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, carbon 1 to 9 represents a nitrogen-containing heteroaromatic ring, or an alkoxy group having 1 to 10 carbon atoms. In some cases, they may be the same or different. In some cases, they may be the same or different. Good, a is 0-4, b is an integer of 0-4.)

(X ¹ represents O, a direct bond or fluorenylidene, respectively. R ² represents fluorine, chlorine, bromine, an optionally fluorinated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, carbon 1 to 9 represents a nitrogen-containing heteroaromatic ring, or an alkoxy group having 1 to 10 carbon atoms. In some cases, they may be the same or different. In some cases, they may be the same or different. Good, a is 0-4, c is an integer of 0-6.)
The polymer electrolyte according to claim 1, comprising a structure represented by: The polymer electrolyte membrane containing the polymer electrolyte as described in any one of Claims 1-3 . A membrane / electrode assembly comprising the polymer electrolyte membrane according to claim 4 . A solid polymer fuel cell comprising the polymer electrolyte membrane according to claim 4 . A polymer electrolyte fuel cell comprising the membrane electrode assembly according to claim 5 .

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