JP2007146111A - Sulfonic acid group-containing polymer, ion-exchange membrane, membrane/electrode assembly, fuel cell, and polymer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion-exchange membrane having improved physical durability and bondability to an electrode catalytic layer; and to provide a new sulfonic acid group-containing polymer usable therefor. <P>SOLUTION: The sulfonic acid group-containing polymer has the whole structures represented by chemical formulas 1 to 4 as essential repeating units. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sulfonic acid group-containing polymer having a novel structure, a composition of the polymer, an ion exchange membrane, a membrane / electrode assembly, and a fuel cell using the polymer.

  In recent years, new power generation technologies with excellent energy efficiency and environmental friendliness have attracted attention. Above all, polymer electrolyte fuel cells using polymer electrolyte membranes have high energy density, and because they have features such as being easy to start and stop because of lower operating temperatures than other types of fuel cells. Developments as power supply devices for electric vehicles and distributed power generation are advancing.

  As the polymer solid electrolyte membrane, a proton conductive ion exchange membrane is usually used. In addition to proton conductivity, the polymer solid electrolyte membrane must have characteristics such as fuel permeation deterrence and mechanical strength that prevent permeation of hydrogen and the like of the fuel. As such a polymer solid electrolyte membrane, for example, a membrane containing a perfluorocarbon sulfonic acid polymer into which a sulfonic acid group is introduced as represented by Nafion (registered trademark) manufactured by DuPont, USA is known. However, since fluorine is contained in the molecule, harmful hydrofluoric acid is generated in the exhaust gas depending on the use conditions, and the environmental load is high at the time of disposal.

  Perfluorocarbon sulfonic acid ion exchange membranes have well-balanced characteristics as electrolyte membranes for fuel cells, but hydrocarbon ion exchange membranes are actively developed to obtain better membranes in terms of cost and performance. Has been done.

  Many hydrocarbon ion exchange membranes use polymers in which ionic groups such as sulfonic acid groups are introduced into heat-resistant polymers such as polyimide and polysulfone. (For example, see Patent Document 1)

  Generally, in a hydrocarbon ion exchange membrane, it is necessary to introduce more ionic groups in order to develop proton conductivity equivalent to that of a perfluorocarbon sulfonic acid ion exchange membrane. However, when the amount of the ionic group is increased, the swellability by water is increased, which causes problems such as dimensional change and deterioration of physical characteristics during moisture absorption. For this reason, there are also hydrocarbon-based ion exchange membranes with improved polymer structure and reduced swelling. (For example, see Patent Document 2)

  However, when trying to reduce the swellability, there is often a problem that the physical durability and the bondability with the electrode catalyst layer are lowered.

JP-T-2004-509224 JP 2004-179779 A

  The present invention has been made against the background of the problems of the prior art. The ion exchange membrane has improved physical durability and bondability with the electrode catalyst layer, a novel sulfonic acid group-containing polymer that can be used therefor, and the ion. An object of the present invention is to provide an exchange membrane and / or a membrane / electrode assembly using the sulfonic acid group-containing polymer, a fuel cell, and the sulfonic acid group-containing polymer composition.

  As a result of intensive studies to solve the above problems, the present inventors have finally completed the present invention. That is, the present invention is as follows.

1. A sulfonic acid group-containing polymer having all the structures represented by chemical formulas 1 to 4 as essential repeating units.

[In the chemical formulas 1 to 4, X represents an —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, and Z ^{1 to} Z ² each independently represent Either O or S atom, Ar ¹ is a trivalent aromatic group, Ar ² is a divalent aromatic group having an electron-withdrawing group, and R ¹ is an alkyl group having 2 to 30 carbon atoms. , X represents an integer of 1 to 6, respectively. ]

2. 2. The sulfonic acid group-containing polymer according to 1 above, wherein Ar ¹ is one or more groups selected from structures represented by chemical formulas 5 to 8.

3. 3. The sulfonic acid group-containing polymer according to 2 above, wherein Ar ¹ has a structure represented by the following chemical formula 5 or 6.

4). 3. The sulfonic acid group-containing polymer as described in 1 or 2 above, wherein R ¹ is a linear alkyl group having 4 to 20 carbon atoms.

5. Ar ² is one or more groups selected from structures represented by chemical formulas 9 to 12 below, The sulfonic acid group-containing polymer as described in any one of 1 to 4 above.

6). 6. The polymer according to 5 above, wherein Ar ² is any one of formulas 11 and 12.

7). Z ¹ and Z ² are both O atoms, The sulfonic acid group-containing polymer as described in any one of 1 to 6 above.

8). 8. The sulfonic acid group-containing polymer according to any one of 1 to 7 above, wherein X is a -S (= O) _2- group.

  9. The sulfonic acid group-containing product according to any one of 1 to 8 above, wherein the molar ratio of the repeating structures represented by chemical formulas 1 to 4 and other repeating structures in the molecule satisfies Formulas 1 to 3. polymer.

[In the above formula, n1 to n4 represent mol% of the repeating structure represented by chemical formulas 1 to 4 in the molecule, and n5 represents mol% of the other repeating structure, respectively. ]

  10. The ion exchange membrane using the polymer in any one of said 1-9.

  11. 11. The ion exchange membrane as described in 10 above, wherein n1 to n5 satisfy the following formula 4 or 5, and are used for a direct methanol fuel cell.

  12 11. The ion exchange membrane as described in 10 above, wherein n1 to n5 satisfy the following formula 6 or 7, and are used for a polymer electrolyte fuel cell using hydrogen as a fuel.

  13. A membrane / electrode assembly using the ion exchange membrane according to any one of 10 to 12 above.

  14 A membrane / electrode assembly, wherein the polymer according to any one of 1 to 9 is used for an electrode catalyst layer.

  15. 15. A fuel cell using the membrane / electrode assembly according to 13 or 14 above.

  16. The composition containing the polymer in any one of said 1-9.

  The ion-exchange membrane obtained from the novel sulfonic acid group-containing polymer or the composition according to the present invention enables high durability and high output when used as a fuel cell, as compared with conventional hydrocarbon ion exchange membranes. It has an excellent effect.

  Hereinafter, the present invention will be described in detail.

  The sulfonic acid group-containing polymer of the present invention is a sulfonic acid group-containing polymer having all the structures represented by the following chemical formulas 1 to 4 as essential repeating units.

[In the chemical formulas 1 to 4, X represents an —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, and Z ^{1 to} Z ² each independently represent Either O or S atom, Ar ¹ is a trivalent aromatic group, Ar ² is a divalent aromatic group having an electron-withdrawing group, and R ¹ is an alkyl group having 2 to 30 carbon atoms. , X represents an integer of 1 to 6, respectively. ]

  The repeating units represented by Chemical Formulas 1 to 4 may be bonded at random, or the same repeating unit may be bonded continuously. In that case, all types of repeating units may be continuously bonded, or only some types may be continuously bonded.

X represents a —S (═O) ₂ — group or a —C (═O) — group, and a —S (═O) ₂ — group is preferable because solubility in a solvent is increased. Moreover, it is preferable that it is -C (= O)-group since it becomes possible to give photocrosslinkability to a polymer.

  Y represents H or a monovalent cation, but when used as a proton exchange membrane of a fuel cell, Y is preferably H. In processing such as dissolution, molding, and film formation, it is preferable that Y is a monovalent cation rather than H because the thermal stability of the sulfonic acid group is increased. Examples of monovalent cations include alkali metal ions such as Na, K and Li, ammonium ions and quaternary amine salts, and alkali metal ions such as Na, K and Li are preferred. The sulfonic acid group which is an alkali metal salt can be converted into a sulfonic acid group by treating the polymer with a strong acid such as sulfuric acid, hydrochloric acid, perchloric acid or an aqueous solution thereof. A polymer having a sulfonic acid group exhibits high proton conductivity, and can be used as a proton exchange resin or a proton exchange membrane. Among them, the proton exchange membrane can be used as an electrolyte of a polymer electrolyte fuel cell, and a fuel cell having excellent performance can be obtained by using the polymer of the present invention.

Z ¹ and Z ² each independently represents either an O or S atom. It is preferable that both Z ¹ and Z ² are O atoms because the cost and toxicity of the monomer do not increase, and coloring in the polymerization hardly occurs. Of Z ¹ and Z ² , at least one of them is preferably an S atom in terms of oxidation resistance, and more preferably, Z ¹ and Z ² are S atoms.

Ar ¹ in Chemical Formula 2 and Chemical Formula 4 is a trivalent aromatic group. The aromatic group here means a group in which the main part is composed of an aromatic group, and partially includes an alkyl group, a halogenated alkyl group, an imino group, a urethane group, a urea group, an ether group, a sulfide. Other groups such as a group, a sulfone group, a carbonyl group, and a phosphine group may be contained. Moreover, the aromatic group represents a group having aromaticity, and a plurality of aromatic groups such as a benzene ring, a heterocyclic ring such as a pyridine ring, a naphthalene ring, an anthracene ring, a biphenylene group, a terphenylene group, It means a condensed or linked compound. Preferably, it is one or more groups selected from structures represented by the following chemical formulas 5 to 8.

In Chemical Formulas 5 to 8, x is preferably 1 or 2. If x increases, it may be difficult to obtain a polymer having a high degree of polymerization. In addition, R ¹ in Chemical Formulas 5 to 8 represents an alkyl group having 2 to 30 carbon atoms. It is more preferable that the number of carbon atoms is 4 to 20 because the effect of improving characteristics is large. R ¹ may have a branch, but is preferably a straight chain. Most preferably, it is a linear alkyl group having 5 to 15 carbon atoms.

Ar ² in Chemical Formula 3 and Chemical Formula 4 is preferably an aromatic group having an electron-withdrawing group. Examples of electron withdrawing groups include sulfone groups, carbonyl groups, sulfonyl groups, phosphine groups, cyano groups, trifluoromethyl groups and other perfluoroalkyl groups, nitro groups, halogen groups, etc., cyano groups, sulfone groups A carbonyl group is preferred. Furthermore, Ar ¹ and Ar ² are preferably one or more groups selected from structures represented by the following chemical formulas 9 to 12. The structure of Chemical Formula 9 is preferable because the solubility in a solvent is increased. Moreover, since it becomes possible to provide photocrosslinkability to a polymer when it is the structure of Chemical formula 10, it is preferable. Moreover, since it is the structure of Chemical formula 11 or 12, since the swelling property of a polymer becomes small, it is preferable. Among the following chemical formulas 9 to 12, the structure of the chemical formula 11 or 12 is preferable, and the structure of the chemical formula 12 is most preferable.

  The molar ratio of the repeating structures represented by chemical formulas 1 to 4 and other repeating structures in the molecule preferably satisfies the formulas 1 to 3. Other repeating structures are not particularly limited, but for example, those containing a phosphonic acid group or a phosphoric acid group are preferred because the oxidation resistance is improved. In addition, if it contains an alkyl group such as a methyl group or a group having crosslinkability such as an allyl group, an ethynyl group, or a maleimide group, the polymer is imparted with a crosslinkability to improve the durability and strength of the ion exchange membrane. This is preferable.

[In the above formula, n1 to n4 represent mol% of the repeating structure represented by chemical formulas 1 to 4 in the molecule, and n5 represents mol% of the other repeating structure, respectively. ]

  Formula 1 represents that the repeating units represented by Chemical Formulas 1 to 4 in the polymer are in the range of 0.9 to 1.0 with respect to all the repeating units, and in the range of 0.95 to 1.0. More preferably, it is in the range of 0.97 to 1.0. When it contains other repeating units other than chemical formulas 1-4, it is more preferable that it is the range of 0.001-0.03 with respect to all the repeating units.

  Formula 2 represents the ratio of the repeating unit containing a sulfonic acid group in the repeating units represented by Chemical Formulas 1 to 4, and is preferably in the range of 0.1 to 0.7. If it is lower than 0.1, sufficient ion conductivity cannot be obtained, and if it is higher than 0.7, the swellability becomes remarkably large or becomes water-soluble, making it difficult to use as an ion exchange membrane. This is not preferable.

  Formula 3 represents the total ratio of the structures represented by Chemical Formula 2 and Chemical Formula 4 in the repeating units represented by Chemical Formulas 1 to 4, and is preferably in the range of 0.01 to 0.95. If it is less than 0.01, a sufficient improvement effect cannot be obtained, and if it is more than 0.95, the swelling property of the film increases, which is not preferable.

  The sulfonic acid group-containing polymer of the present invention can be used for an ion exchange resin, an ion exchange membrane, a moisture absorbent resin, a moisture absorbent membrane, a moisture permeable membrane, an electrolytic membrane, and the like, and is particularly preferably used as an ion exchange membrane. Furthermore, the ion exchange membrane using the sulfonic acid group-containing polymer of the present invention can be used as a proton exchange membrane by converting the sulfonic acid group to a sulfonic acid type, and is particularly suitable for a proton exchange membrane for a fuel cell. The sulfonic acid group-containing polymer of the present invention is also suitable for use as an adhesive when an ion exchange membrane or the like is bonded to an electrode or a catalyst.

  When the ion exchange membrane of the present invention is used as a proton exchange membrane of a direct methanol fuel cell that directly uses an aqueous methanol solution as a fuel, it is preferable that the following mathematical expressions 4 and 5 are satisfied.

  In Formula 4, if the value of (n1 + n2) / (n1 + n2 + n3 + n4) is smaller than 0.1, sufficient proton conductivity cannot be obtained, and the output of the fuel cell is lowered. This is not preferable because the amount of light passing through the fuel cell becomes too large and the output of the fuel cell decreases. A more preferable range of (n1 + n2) / (n1 + n2 + n3 + n4) is 0.1 to 0.4. Further, when the concentration of the aqueous methanol solution used as the fuel is low, the larger (n1 + n2) / (n1 + n2 + n3 + n4) is, the higher the proton conductivity is, and the higher the output of the fuel cell. On the other hand, when a high-concentration methanol aqueous solution is used, a decrease in (n1 + n2) / (n1 + n2 + n3 + n4) can suppress a decrease in output due to the permeation of methanol and increase the output of the fuel cell.

  The value of (n2 + n4) / (n1 + n2 + n3 + n4) is preferably in the range of 0.05 to 0.95. If it is smaller than 0.05, poor bonding tends to occur when the electrode or catalyst is bonded to the ion exchange membrane, and if it is larger than 0.95, the swelling property becomes too large, which is not preferable. A more preferred range is in the range of 0.2 to 0.8. When the value of (n1 + n2) / (n1 + n2 + n3 + n4) is smaller than 0.2, (n2 + n4) / (n1 + n2 + n3 + n4) is preferably in the range of 0.4 to 0.8. When the value of (n1 + n2) / (n1 + n2 + n3 + n4) is larger than 0.2, (n2 + n4) / (n1 + n2 + n3 + n4) is preferably in the range of 0.1 to 0.5.

  When the ion exchange membrane of the present invention is used as a proton exchange membrane of a fuel cell using hydrogen as a fuel, it is preferable that the following formulas 6 and 7 are satisfied.

  In Formula 6, when the value of (n1 + n2) / (n1 + n2 + n3 + n4) is smaller than 0.3, sufficient proton conductivity cannot be obtained, and the output of the fuel cell is lowered. When the value is larger than 0.7, the membrane swells. This is not preferable because the property becomes so large that breakage and output decrease are likely to occur. A more preferable range of (n1 + n2) / (n1 + n2 + n3 + n4) is 0.35 to 0.7, and more preferably 0.4 to 0.5.

  The value of (n2 + n4) / (n1 + n2 + n3 + n4) is preferably in the range of 0.01 to 0.25. If it is smaller than 0.01, poor bonding is likely to occur when the electrode or catalyst is bonded to the ion exchange membrane, and if it is larger than 0.25, the swelling property becomes too large, which is not preferable. A more preferred range is from 0.1 to 0.2.

  The ion exchange membrane of the present invention can be made into a membrane / electrode assembly by joining electrodes and catalysts. Further, the sulfonic acid group-containing polymer of the present invention can be used as an adhesive with an electrode or a catalyst for a membrane other than the ion exchange membrane of the present invention. When the sulfonic acid group-containing polymer of the present invention is used as an adhesive, it is preferable that Y in Chemical Formulas 1 and 2 is H and the sulfonic acid group is in acid form. When the sulfonic acid group is used in the form of a salt with a cation, the sulfonic acid group can be converted into an acid form by acid treatment after bonding.

  The sulfonic acid group-containing polymer of the present invention can be dissolved and dispersed in an appropriate solvent and used as a composition. Solvents that can be used include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, hexamethylphosphonamide, N-morpholine oxide, and the like. Polar solvents such as aprotic organic polar solvents, alcohol solvents such as methanol and ethanol, ketone solvents such as acetone, ether solvents such as diethyl ether, mixtures of these organic solvents, and mixtures with water However, it is not limited to these.

  The concentration of the polymer solution is preferably in the range of 0.1 to 50% by weight. When a film, fiber, or the like is molded from a solution, the concentration is more preferably in the range of 5 to 50% by weight, and further preferably in the range of 10 to 40% by weight. When the solution is used as an adhesive, the concentration is more preferably in the range of 0.1 to 20% by weight. When the solution is used as an adhesive, it may contain other components such as carbon particles carrying a catalyst such as Pt and PT-Ru, and a fluororesin.

  In the sulfonic acid group-containing polymer of the present invention, chemical formulas 13A to 13X, which are specific examples of preferred structures, are shown below, but the scope of the present invention is not limited to the following. Note that R in the chemical formulas 13A to 13X represents an alkyl group having 2 to 30 carbon atoms. Specific examples of R include n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-dodecyl group, n-tetradecyl group. Groups, n-hexadecyl groups, n-octadecyl groups, n-dodecyl groups, isobutyl groups, tertiary butyl groups, amyl groups, and the like, but are not limited thereto.

  Among the chemical formulas 13A to 13X, the chemical formulas 13A, 13B, 13G, 13H, 13M, 13N, 13S, and 13T are preferable because of excellent proton conductivity and swelling resistance, and the chemical formulas 13A, 13G, 13M, and 13S are more preferable. 13A or 13B is more preferred.

  In the chemical formulas 13A to 13X, n1, n2, n3, and n4 preferably satisfy the following formulas 8 and 9.

  (N1 + n2) / (n1 + n2 + n3 + n4) is preferably in the range of 0.1 to 0.7. If it is lower than 0.1, sufficient ion conductivity cannot be obtained, and if it is higher than 0.7, the swellability becomes remarkably large or becomes water-soluble, making it difficult to use as an ion exchange membrane. This is not preferable.

  (N2 + n4) / (n1 + n2 + n3 + n4) is preferably in the range of 0.01 to 0.95. If it is less than 0.01, a sufficient improvement effect cannot be obtained, and if it is more than 0.95, the swelling property of the film increases, which is not preferable. In order to obtain a sufficient improvement effect, it is necessary that the ratio of the biphenyl group derived from Chemical Formula 1 and Chemical Formula 3 to the alkyl group derived from Chemical Formula 2 and Chemical Formula 4 is appropriate in the polymer. If the number of biphenyl groups is small, the swelling property of the film may be significantly reduced, which may adversely affect the form stability and durability. If the number of alkyl groups is small, the properties such as bondability and durability will be improved. The effect may not be obtained.

  In the sulfonic acid group-containing polymer of the present invention, the repeating structure represented by the chemical formulas 2 and 4 increases the flexibility of the polymer, makes it difficult to break against deformation, and decreases the glass transition temperature. This brings about effects such as improved bonding with the. In addition, the repeating structure represented by the above chemical formulas 1 and 3 has the effect of reducing the swelling property of the whole polymer or reducing the methanol permeability.

  When the ion exchange membrane of the present invention is used as a proton exchange membrane of a direct methanol fuel cell that directly uses an aqueous methanol solution as a fuel, it is preferable that the following formulas 10 and 11 are satisfied.

  When (n1 + n2) / (n1 + n2 + n3 + n4) is smaller than 0.1, sufficient proton conductivity cannot be obtained, and the output of the fuel cell is lowered. When it is larger than 0.5, the amount of methanol passing through the membrane is large. Since it becomes too much and the output of a fuel cell falls, the more preferable range of (n1 + n2) / (n1 + n2 + n3 + n4) is 0.1-0.4. Further, when the concentration of the aqueous methanol solution used as the fuel is low, the larger ((n1 + n2) / (n1 + n2 + n3 + n4)), the higher the proton conductivity, and the higher the output of the fuel cell. In the case of using, when (n1 + n2) / (n1 + n2 + n3 + n4) is smaller, it is possible to suppress a decrease in output due to the permeation of methanol and to increase the output of the fuel cell.

  The value of (n2 + n4) / (n1 + n2 + n3 + n4) is preferably in the range of 0.05 to 0.95. If it is smaller than 0.05, poor bonding tends to occur when the electrode or catalyst is bonded to the ion exchange membrane, and if it is larger than 0.95, the swelling property becomes too large, which is not preferable. A more preferred range is in the range of 0.2 to 0.8. When the value of (n1 + n2) / (n1 + n2 + n3 + n4]) is smaller than 0.2, (n2 + n4) / (n1 + n2 + n3 + n4) is preferably in the range of 0.4 to 0.8. When the value of (n1 + n2) / (n1 + n2 + n3 + n4) is larger than 0.2, ((n2 + n4) / (n1 + n2 + n3 + n4) is preferably in the range of 0.1 to 0.5.

  When the ion exchange membrane of the present invention is used as a proton exchange membrane of a fuel cell using hydrogen as a fuel, it is preferable that the following formulas 12 and 13 are satisfied.

  If (n1 + n2) / (n1 + n2 + n3 + n4) is smaller than 0.3, sufficient proton conductivity cannot be obtained, and the output of the fuel cell is lowered. If it is larger than 0.7, the swelling property of the membrane becomes too large. It is not preferable because breakage and output reduction are likely to occur. A more preferable range of (n1 + n2) / (n1 + n2 + n3 + n4) is 0.35 to 0.7, and more preferably 0.4 to 0.5.

  The value of (n2 + n4) / (n1 + n2 + n3 + n4) is preferably in the range of 0.01 to 0.25. If it is smaller than 0.01, poor bonding is likely to occur when the electrode or catalyst is bonded to the ion exchange membrane, and if it is larger than 0.25, the swelling property becomes too large, which is not preferable. A more preferred range is from 0.1 to 0.2.

  The sulfonic acid group-containing polymer of the present invention can be polymerized by an aromatic nucleophilic substitution reaction from a mixture of monomers containing compounds represented by chemical formulas 14 to 17 as essential components.

In Chemical Formulas 14 to 17, X is a —S (═O) ₂ — group or —C (═O) — group, Y is H or a monovalent cation, and Z ³ and Z ⁵ are each independently Any one of Cl atom, F atom, I atom, Br atom and nitro group, Z ⁴ and Z ⁶ are each independently OH group, SH group, —O—NH—C (═O) —R group, One of the —S—NH—C (═O) —R ′ groups, {R ′ represents an aromatic or aliphatic hydrocarbon group; }, Ar ¹ is a trivalent aromatic group, Ar ² is a perfluoroalkyl group such as a sulfone group, a carbonyl group, a sulfonyl group, a phosphine group, a cyano group or a trifluoromethyl group, a nitro group, a halogen atom in the molecule. Represents an aromatic group having an electron-withdrawing group such as a group;

  Specific examples of the compound represented by Chemical Formula 14 include 3,3′-disulfo-4,4′-dichlorodiphenylsulfone, 3,3′-disulfo-4,4′-difluorodiphenylsulfone, 3,3′- Examples include disulfo-4,4′-dichlorodiphenyl ketone, 3,3′-disulfo-4,4′-difluorodiphenyl sulfone, and those whose sulfonic acid group is converted to a salt with a monovalent cationic species. . The monovalent cation species may be sodium, potassium, other metal species, various amines, or the like, but is not limited thereto. Examples of the compound represented by the chemical formula 9 in which the sulfonic acid group is a salt include sodium 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone, 3,3′-disulfonic acid. Sodium-4,4′-difluorodiphenylsulfone, sodium 3,3′-disulfonate-4,4′-dichlorodiphenylketone, sodium 3,3′-disulfonate-4,4′-difluorodiphenylsulfone, 3,3 'Sodium disulfonate-4,4'-difluorodiphenyl ketone, potassium 3,3'-disulfonate 4,4'-dichlorodiphenyl sulfone, potassium 3,3'-disulfonate 4,4'-difluorodiphenyl sulfone, 3, , 3'-Disulfonic acid potassium 4,4'-dichlorodiphenyl ketone, 3,3'-disulfone Potassium 4,4'-difluoro diphenyl sulfone, etc. 3,3'-disulfonic acid potassium 4,4'-difluoro diphenyl ketone and the like.

  Specific examples of the compound represented by Chemical Formula 15 include 4-ethylresorcinol, 4-hexylresorcinol, 2-hexylhydroquinone, 2-octylhydroquinone, 2-octadadecylhydroquinone, 2-tertiarybutylhydroquinone, 2,5- Ditertiary butyl hydroquinone, 2,5-ditertiary amyl hydroquinone, 2,2′-dihexyl-4,4′-dihydroxybiphenyl, 1-octyl-2,6-dihydroxynaphthalene, 2-hexyl-1,5-dihydroxynaphthalene 4-hexyl resorcinol and 2-tertiary butyl hydroquinone are preferable.

  Examples of the compound represented by Chemical Formula 16 include compounds having a leaving group in a nucleophilic substitution reaction such as halogen and nitro group on the same aromatic ring and an electron-withdrawing group for activating it. Specific examples include 2,6-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2,6-difluorobenzonitrile, 2,4-difluorobenzonitrile, 4,4′-dichlorodiphenylsulfone, 4,4 ′. -Difluorodiphenyl sulfone, 4,4'-difluorobenzophenone, 4,4'-dichlorobenzophenone, decafluorobiphenyl, and the like, but not limited thereto, other aromatics active in aromatic nucleophilic substitution reaction A group dihalogen compound, an aromatic dinitro compound, an aromatic dicyano compound, and the like can also be used.

  Examples of the compound represented by the chemical formula 17 include 4,4'-biphenol, 4,4'-dimercaptobiphenol, and 4,4'-biphenol is preferable. The monomer having the structure represented by Chemical Formula 17 has effects such as increasing the flexibility of the polymer, suppressing brittle fracture against deformation, and improving the bonding property with the electrode by lowering the glass transition temperature. Yes.

  In the above aromatic nucleophilic substitution reaction, other various activated dihalogen aromatic compounds, dinitroaromatic compounds, bisphenol compounds, and bisthiophenol compounds can be used in combination with the compounds represented by chemical formulas 14 to 17. .

  Examples of other bisphenol compounds or bisthiophenol compounds include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (3-methyl-4-hydroxyphenyl) fluorene, and 4,4′-biphenol. Bis (4-hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 3,3-bis (4-hydroxyphenyl) pentane, 2 , 2-bis (4-hydroxy-3,5-dimethylphenyl) propane, bis (4-hydroxy-3,5-dimethylphenyl) methane, bis (4-hydroxy-2,5-dimethylphenyl) methane, bis ( 4-hydroxyphenyl) phenylmethane, bis (4-hydroxyphenyl) diphenylmethane, hydride Quinone, resorcin, bis (4-hydroxyphenyl) ketone, 1,4-benzenedithiol, 1,3-benzenedithiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, 2 , 2-bis (4-hydroxyphenyl) hexafluoropropane, 4,4′-thiobisbenzenethiol, 4,4′-oxybisbenzenethiol, bis (4-hydroxyphenyl) sulfide, 4,4′-dihydroxydiphenyl ether Diallyl bisphenol A, 10- (2,5-dihydroxyphenyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and the like. Can be used for polymerization of polyarylene ether compounds by substitution reaction It is possible to use various aromatic diols or various aromatic dithiol, not limited to the above compounds.

  When the sulfonic acid group-containing polymer in the present invention is polymerized by an aromatic nucleophilic substitution reaction, a compound having a structure represented by chemical formulas 14 to 17 and, if necessary, other activated dihalogen aromatic compounds or dinitroaromatic compounds. Or an aromatic diol or aromatic dithiol and a reaction in the presence of a basic compound to obtain a polymer. By setting the molar ratio of the reactive halogen group or nitro group to the reactive hydroxy group and thiol group in the monomer to an arbitrary molar ratio, the degree of polymerization of the resulting polymer can be adjusted. Is 0.8 to 1.2, more preferably 0.9 to 1.1, more preferably 0.95 to 1.05, and 1 to obtain a polymer with the highest degree of polymerization. Can do.

  The polymerization can be carried out in the temperature range of 0 to 350 ° C., but is preferably 50 to 250 ° C. When the temperature is lower than 0 ° C., the reaction does not proceed sufficiently, and when the temperature is higher than 350 ° C., the polymer tends to be decomposed. The reaction can be carried out in the absence of a solvent, but is preferably carried out in a solvent. Examples of the solvent that can be used include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, diphenyl sulfone, sulfolane, and the like. And any solvent that can be used as a stable solvent in the aromatic nucleophilic substitution reaction. These organic solvents may be used alone or as a mixture of two or more.

  Examples of basic compounds include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, etc., which can convert aromatic diols and aromatic dimercapto compounds into an active phenoxide structure. If it is, it can be used without being limited to these. The basic compound can be polymerized satisfactorily when used in an amount of 100 mol% or more based on the total amount of the bisphenol compound and the bisthiophenol compound, preferably 105 to The range is 125 mol%. An excessive amount of bisphenol compound or bisthiophenol compound is not preferable because it causes side reactions such as decomposition.

  Further, in the above polymerization reaction, a bisphenol compound or bisthiophenol compound reacted with an isocyanate compound without reacting with a carbamoylate and an activated dihalogen aromatic compound or dinitro aromatic compound directly without using a basic compound. It can also be reacted.

  In the aromatic nucleophilic substitution reaction, water may be generated as a by-product. In this case, regardless of the polymerization solvent, water can be removed from the system as an azeotrope by coexisting toluene or the like in the reaction system. As a method for removing water out of the system, a water absorbing material such as molecular sieve can also be used. When the aromatic nucleophilic substitution reaction is carried out in a solvent, it is preferable to charge the monomer so that the resulting polymer concentration is 5 to 50% by weight. When the amount is less than 5% by weight, the degree of polymerization tends to be difficult to increase. On the other hand, when the amount is more than 50% by weight, the viscosity of the reaction system becomes too high, and the post-treatment of the reaction product tends to be difficult. After completion of the polymerization reaction, the solvent is removed from the reaction solution by evaporation, and the residue is washed as necessary to obtain the desired polymer. In addition, the polymer can be obtained by precipitating the polymer as a solid by adding the reaction solution in a solvent having low polymer solubility, and collecting the precipitate by filtration. In addition, a polymer solution can be obtained by removing by-product salts by filtration.

  The sulfonic acid group-containing polymer in the present invention preferably has a polymer log viscosity measured by a method described later of 0.1 dl / g or more. When the logarithmic viscosity is less than 0.1 dl / g, the membrane tends to become brittle when molded as an ion exchange membrane. The logarithmic viscosity is more preferably 0.3 dl / g or more. On the other hand, if the logarithmic viscosity exceeds 5 dl / g, problems in processability such as difficulty in dissolving the polymer occur, which is not preferable. As a solvent for measuring the logarithmic viscosity, polar organic solvents such as N-methylpyrrolidone and N, N-dimethylacetamide can be generally used. When the solubility in these is low, concentrated sulfuric acid is used. It can also be measured.

  The ion exchange capacity of the sulfonic acid group-containing polymer in the present invention is preferably 0.1 meq / g, more preferably 3.5 meq / g or less. A small ion exchange capacity is not preferable because proton conductivity decreases. As the ion exchange capacity increases, proton conductivity increases, but at the same time, problems such as membrane swelling and water dissolution are likely to occur. A more preferred range is 0.5 to 3.5 meq / g, and a further preferred range is 1.0 to 2.5 meq / g.

  The ion exchange membrane in the present invention can be of any thickness, but if it is 10 μm or less, it becomes difficult to satisfy the predetermined characteristics, so that it is preferably 10 μm or more, and more preferably 20 μm or more. Moreover, since manufacture will become difficult when it becomes 300 micrometers or more, it is preferable that it is 300 micrometers or less.

  The sulfonic acid group-containing polymer in the present invention can be used as a simple substance, but can also be used as a resin composition in combination with other polymers. Examples of these polymers include polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyamides such as nylon 6, nylon 6,6, nylon 6,10 and nylon 12, polymethyl methacrylate and polymethacrylate. Acrylate resins such as polymethyl acrylate, polyacrylic acid esters, polyacrylic acid resins, polymethacrylic acid resins, polyethylene, polypropylene, various polyolefins including polystyrene and diene polymers, polyurethane resins, cellulose acetate, Cellulosic resins such as ethyl cellulose, polyarylate, aramid, polycarbonate, polyphenylene sulfide, polyphenylene oxide, polysulfone, polyether Thermal curing of aromatic polymers such as sulfone, polyether ether ketone, polyether imide, polyimide, polyamide imide, polybenzimidazole, polybenzoxazole, polybenzthiazole, epoxy resin, phenol resin, novolac resin, benzoxazine resin There are no particular restrictions on the conductive resin. A resin composition with a basic polymer such as polybenzimidazole or polyvinylpyridine can be said to be a preferable combination for improving the polymer dimensionality, and when a sulfonic acid group is further introduced into these basic polymers, The processability of the composition becomes more preferable. When used as these resin compositions, the sulfonic acid group-containing polymer of the present invention is preferably contained in an amount of 50% by mass or more and less than 100% by mass of the entire resin composition. More preferably, it is 70 mass% or more and less than 100 mass%. When the content of the sulfonic acid group-containing polymer of the present invention is less than 50% by weight of the entire resin composition, the sulfonic acid group concentration of the ion exchange membrane containing this resin composition is lowered, and good ion conductivity is obtained. In addition, the unit containing a sulfonic acid group tends to be a discontinuous phase and the mobility of ions to be conducted tends to be lowered. In addition, the composition of the present invention, if necessary, for example, an antioxidant, a heat stabilizer, a lubricant, a tackifier, a plasticizer, a crosslinking agent, a viscosity modifier, an antistatic agent, an antibacterial agent, an antifoaming agent, Various additives such as a dispersant and a polymerization inhibitor may be included.

  The ion exchange membrane of the present invention can be obtained from the composition containing the sulfonic acid group-containing ion exchange resin of the present invention by any method such as extrusion, rolling or casting. Among these, it is preferable to mold from a solution dissolved in an appropriate solvent. A method of obtaining a molded body from a solution can be performed using a conventionally known method. For example, the molded product can be obtained by removing the solvent by heating, drying under reduced pressure, immersion in a compound non-solvent that can be mixed with a solvent that dissolves the compound, or the like. When the solvent is an organic solvent, the solvent is preferably distilled off by heating or drying under reduced pressure. At this time, if necessary, it can be molded in a form combined with other compounds. When combined with a compound having a similar dissolution behavior, it is preferable in that good molding can be achieved. The sulfonic acid group in the molded article thus obtained may contain a salt form with a cationic species, but it is converted to a free sulfonic acid group by acid treatment if necessary. You can also

  The most preferable method for forming an ion exchange membrane from a sulfonic acid group-containing polymer and a resin composition thereof in the present invention is casting from a solution, and the solvent is removed from the cast solution as described above to remove the ion exchange membrane. Can be obtained. Examples of the solution include a solution using an organic solvent such as N-methylpyrrolidone, N, N-dimethylformamide, and dimethyl sulfoxide, and in some cases, an alcohol solvent. The removal of the solvent is preferably by drying from the viewpoint of the uniformity of the ion exchange membrane. Moreover, in order to avoid decomposition | disassembly and alteration of a compound or a solvent, it can also dry at the lowest temperature possible under reduced pressure. Further, when the viscosity of the solution is high, when the substrate or the solution is heated and cast at a high temperature, the viscosity of the solution is lowered and the casting can be easily performed. The thickness of the solution at the time of casting is not particularly limited, but is preferably 10 to 2000 μm. More preferably, it is 50-1500 micrometers. If the thickness of the solution is thinner than 10 μm, the form as an ion exchange membrane tends to be not maintained, and if it is thicker than 2000 μm, a non-uniform film tends to be easily formed. As a method for controlling the cast thickness of the solution, a known method can be used. For example, the thickness can be controlled by the amount and concentration of the solution by making the thickness constant using an applicator, a doctor blade or the like, or making the cast area constant using a glass petri dish or the like. The cast solution can obtain a more uniform film by adjusting the solvent removal rate. For example, in the case of heating, the evaporation rate can be reduced by lowering the temperature in the first stage. In addition, when immersed in a non-solvent such as water, the coagulation rate of the compound can be adjusted by leaving the solution in air or an inert gas for an appropriate time. When used as an ion exchange membrane, the sulfonic acid group in the membrane may contain a metal salt, but can be converted to free sulfonic acid by an appropriate acid treatment. In this case, it is also effective to immerse the membrane in an aqueous solution of sulfuric acid, hydrochloric acid, etc. with or without heating.

  The membrane / electrode assembly of the present invention can be produced by bonding an electrode catalyst layer to the proton exchange membrane of the present invention. In this case, as the adhesive between the membrane, the electrode, and the catalyst, a hydrocarbon-based proton conductive polymer or a fluorine-based proton conductive polymer such as Nafion (registered trademark) solution can be used. As the hydrocarbon proton conductive polymer as the adhesive, it is preferable to use the polymer described as the polymer constituting the proton exchange membrane in the present invention from the viewpoint of bonding properties and methanol permeation suppression. For example, the electrode can be joined by applying a binder solution containing a catalyst to the proton exchange membrane, or hot-pressing the electrode on which the catalyst layer is formed by applying the binder solution containing the catalyst in advance with the proton exchange membrane. The binder layer containing the catalyst formed in a separate sheet shape in advance can be transferred to the proton exchange membrane by hot pressing, and then bonded to the electrode by hot pressing. Alternatively, a membrane / electrode assembly can be obtained by applying a binder solution containing a catalyst to the proton exchange membrane and drying it. Arbitrary methods can be used as a method for obtaining the membrane / electrode assembly, and the method is not limited thereto.

  When the membrane / electrode assembly of the present invention is produced, the proton conductive polymer used for the proton exchange membrane or the binder may be a free acid or may form a salt. When a salt is formed, it is preferably a salt with an alkali metal ion such as Na, K, or Li. It is preferable to form a salt because the stability of the ionic group is improved. Both the proton exchange membrane and the binder, or any one of the ionic groups in the proton conducting polymer may be a salt. The ionic group forming the salt can be converted into an acid type ionic group by treatment with an aqueous solution of a strong acid such as hydrochloric acid or sulfuric acid. The acid treatment may be performed on each of the proton exchange membrane and the binder, or may be performed after forming a membrane / electrode assembly. In any case, it is preferable to wash sufficiently so that the free acid used in the acid treatment does not remain.

  The fuel cell of the present invention can be produced using the ion exchange membrane or the membrane / electrode assembly of the present invention. The ion exchange membrane of the present invention is suitable for a polymer electrolyte fuel cell. The fuel cell of the present invention includes, for example, an oxygen electrode, a fuel electrode, the proton exchange membrane of the present invention disposed between the electrodes, an oxidant flow path provided on the oxygen electrode side, and a fuel electrode. It has a fuel flow path provided on the side. A fuel cell stack can be obtained by connecting such unit cells with a conductive separator. By adjusting the amount of sulfonic acid group in the polymer, it can be used for a direct methanol fuel cell using methanol as a fuel or a fuel cell using hydrogen as a fuel. Also dimethyl ether, hydrogen. It can also be suitably used for fuel cells using other substances such as formic acid as fuel, and can be used for any known application as an ion exchange membrane such as an electrolytic membrane and a separation membrane.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to these Examples. Various measurements were performed as follows.

Logarithmic viscosity: The polymer powder was dissolved in N-methylpyrrolidone at a concentration of 0.5 g / dl, and the viscosity was measured using a Ubbelohde viscometer in a constant temperature bath at 30 ° C., and the logarithmic viscosity ln [ta / tb] / Evaluation was made by c (ta is the number of seconds for dropping the sample solution, tb is the number of seconds for dropping only the solvent, and c is the polymer concentration).

Proton conductivity: A platinum wire (diameter: 0.2 mm) is pressed against the surface of a strip-shaped membrane sample on a probe for self-made measurement (made of tetrafluoroethylene resin), and water at 25 ° C. or constant temperature and humidity at 80 ° C. and 95%. The sample was held in the tank, and the impedance between the platinum wires was measured by SOLARTRON 1250 FREQUENCY RESPONSE ANALYSER. The measurement was performed while changing the distance between the electrodes, and the conductivity obtained by canceling the contact resistance between the film and the platinum wire was calculated from the gradient obtained by plotting the distance measured between the electrodes and the resistance measurement value estimated from the CC plot.
Conductivity [S / cm] = 1 / film width [cm] × film thickness [cm] × resistance interelectrode gradient [Ω / cm]

Methanol permeability: The liquid fuel permeation rate of the ion exchange membrane was measured as the methanol permeation rate by the following method. An ion exchange membrane immersed in a 5 M (mol / liter) aqueous methanol solution adjusted to 25 ° C. for 24 hours is sandwiched in an H-type cell, 100 ml of 5 M aqueous methanol solution is placed on one side of the cell, and 100 ml of ultrapure water ( 18 MΩ · cm) was injected, and the amount of methanol diffusing into the ultrapure water through the ion-exchange membrane while stirring the cells on both sides at 25 ° C. was calculated using a gas chromatograph ( area of the ion exchange membrane, 2.0 cm ^2). A methanol permeability coefficient was determined from the obtained methanol permeation rate and the film thickness of the sample.

Power generation evaluation of hydrogen-fueled fuel cell (PEFC): 20% Nafion (registered trademark) solution made by DuPont, commercially available 40% Pt catalyst-supported carbon (Tanaka Kikinzoku Kogyo Co., Ltd. Fuel Cell Catalyst TEC10V40E) and a small amount After adding ultrapure water and isopropanol, the mixture was stirred until uniform to prepare a catalyst paste. This catalyst paste was uniformly applied to Toray carbon paper TGPH-060 so that the amount of platinum deposited was 0.5 mg / cm ² and dried to prepare a gas diffusion layer with an electrode catalyst layer. An ion exchange membrane is sandwiched between the gas diffusion layers with the electrode catalyst layer so that the electrode catalyst layer is in contact with the membrane, and the membrane is pressurized and heated at 130 ° C. and 2 MPa for 3 minutes by a hot press method. -It was set as the electrode assembly. The joined body was assembled in an evaluation fuel cell FC25-02SP manufactured by Electrochem, and hydrogen and air humidified at 75 ° C. were supplied to the anode and the cathode at a cell temperature of 80 ° C., and the power generation characteristics were evaluated. The output voltage at a current density of 0.5 A / cm ² immediately after the start was taken as the initial characteristics. Moreover, as durability evaluation, continuous operation was performed on said conditions, measuring an open circuit voltage at the rate of once per hour. The time when the open circuit voltage decreased by 10% or more from the value immediately after the start was defined as the endurance time. Durability evaluation was performed with 1000 hours as the upper limit.

Power generation evaluation of direct methanol fuel cell (DMFC): After adding a small amount of ultrapure water and isopropyl alcohol to Pt / Ru catalyst-supported carbon (TEC61E54, Tanaka Kikinzoku Kogyo Co., Ltd.) and moistening, 20% Nafion (DuPont) (Registered trademark) solution (product number: SE-20192) was added so that the weight ratio of Pt / Ru catalyst-carrying carbon to Nafion (registered trademark) was 2.5: 1. Next, stirring was performed to prepare an anode catalyst paste. The catalyst paste was applied to Toray carbon paper TGPH-060 to be a gas diffusion layer by screen printing so that the adhesion amount of platinum was 2 mg / cm ^2, and a carbon paper with an electrode catalyst layer for anode was produced. . Further, after adding a small amount of ultrapure water and isopropyl alcohol to Pt catalyst-supporting carbon (Tanaka Kikinzoku Kogyo Co., Ltd. TEC10V40E) and moistening, a 20% Nafion (registered trademark) solution (product number: SE-20192) manufactured by DuPont is used. A cathode catalyst paste was prepared by adding a Pt catalyst supporting carbon and Nafion (registered trademark) in a weight ratio of 2.5: 1 and stirring. The catalyst paste, the adhesion amount of platinum to carbon manufactured by Toray Industries, water-repellent paper TGPH-060 is applied and dried so that 1 mg / cm ^2, to prepare a cathode electrode catalyst layer with carbon paper. By sandwiching the membrane sample between the two types of carbon paper with the electrode catalyst layer so that the electrode catalyst layer is in contact with the membrane sample, pressurizing and heating at 160 ° C. and 8 MPa for 3 minutes by a hot press method, A membrane-electrode assembly was obtained. This joined body was incorporated into an evaluation fuel cell FC25-02SP manufactured by Electrochem, and a power generation test was performed using a fuel cell power generation tester (manufactured by Toyo Corporation). Power generation was performed at a cell temperature of 40 ° C. while supplying high-purity air gas (80 ml / min) adjusted to 40 ° C. and a 5 mol / l aqueous methanol solution (1.5 ml / min) to the anode and the cathode, respectively. . The output voltage at a current density of 0.02 A / cm 2 and the resistance value measured by the current interruption method were measured.

Ion exchange capacity: A sample dried for 1 hour at 100 ° C. and allowed to stand overnight at room temperature in a nitrogen atmosphere was weighed, stirred with an aqueous sodium hydroxide solution, and then ion exchange capacity was determined by back titration with an aqueous hydrochloric acid solution.

Softening temperature: 10 Hz dynamic strain while heating 5 mm wide ion exchange membrane with Rheogel E-4000 (manufactured by Toki Sangyo Co., Ltd.) with chuck width of 10 mm from 50 ° C. to 250 ° C. at 2 ° C./min. The dynamic viscoelasticity was measured. The temperature at the inflection point at which E ′ greatly decreases as the temperature rises was defined as the softening temperature.

<Example 1>
Sodium 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone (abbreviation: S-DCDPS) 60.00 g (122.1 mmol), 2,6-dichlorobenzonitrile (abbreviation: DCBN 26.74 g (155. 5 mol), 4,4′-biphenol (abbreviation: BP) 41.35 g (222.1 mmol), 4-hexylresorcinol (abbreviation: HRC) 10.79 g (55.52 mmol), potassium carbonate 42.20 g (305.3 mmol) ), 32 g of dried molecular sieve 3-A was weighed into a 1000 ml four-necked flask and flushed with nitrogen, 360 ml of N-methyl-2-pyrrolidone (abbreviation: NMP) was added, and the reaction temperature was adjusted while stirring. The reaction was continued by raising the viscosity to 195 to 200 ° C. and increasing the viscosity of the system sufficiently (about 16 hours). After cooling, the precipitated molecular sieve was removed and the solution was precipitated in strands in water, and the resulting polymer was washed in boiling water for 1 hour and dried. The ¹ H-NMR spectrum measured at room temperature in deuterated dimethyl sulfoxide is shown in Fig. 1. 7 g of the polymer was dissolved in 28 g of NMP and cast on a glass plate on a hot plate to a thickness of about 400 µm. After heating at 80 ° C. for 0.5 hour, 120 ° C. for 0.5 hour, and 150 ° C. for 0.5 hour, the film was dried in an oven at 150 ° C. in a nitrogen atmosphere for 1 hour to peel the film from the glass plate. The obtained film was immersed in pure water at room temperature for 1 day and then immersed in a 2 mol / L sulfuric acid aqueous solution for 2 hours, and then the film was washed with pure water until the washing water became neutral, And dried in location, it was. Obtained ion-exchange membrane was evaluated to obtain the ion-exchange membrane.

<Examples 2 to 4>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 except that the amounts of S-DCDPS, DCBN, HRC, and BP were changed.

<Example 5>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 except that 2-tertiary butyl hydroquinone (abbreviation: TBQ) was used instead of HRC.

<Example 6>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 2 except that TBQ was used instead of HRC.

<Example 7>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 except that 2,2′-dihexyl-4,4′-dihydroxybiphenyl (abbreviation: HBP) was used instead of HRC.

<Example 8>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 2 except that HBP was used instead of HRC.

<Example 9>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 except that 2-hexyl-1,5-dihydroxynaphthalene (abbreviation: HHN) was used instead of HRC.

<Example 10>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 2 except that HHN was used instead of HRC.

<Comparative Example 1>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 using a sulfonic acid group-containing polymer represented by the following chemical formula 18 having a known structure.

<Comparative example 2>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 using a sulfonic acid group-containing polymer represented by the following chemical formula 19 having a known structure.

<Comparative Example 3>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 using a sulfonic acid group-containing polymer represented by the following chemical formula 20 having a known structure.

<Comparative example 4>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 using a sulfonic acid group-containing polymer represented by the following chemical formula 21 having a known structure.

<Comparative Example 5>
Various evaluations were performed on Nafion (registered trademark) 112, which is a commercially available ion exchange membrane.

<Comparative Example 6>
Various evaluations were performed on Nafion (registered trademark) 117, which is a commercially available ion exchange membrane.

  Table 1 shows the evaluation results of the ion exchange membranes of Examples and Comparative Examples.

  From Table 1, the ion exchange membranes (Examples 2, 3, 6, 8, 10) for direct methanol fuel cells (DMFC) in the present invention are the ion exchange membranes of Comparative Examples (Comparative Examples 1-2). On the other hand, it is clear that the bondability is improved by lowering the softening temperature, and a high output voltage is obtained by lowering the resistance value. In addition, it is clear that Nafion (registered trademark) 117 (Comparative Example 6), which is an existing ion exchange membrane, is an ion exchange membrane having significantly small methanol permeability and excellent methanol resistance. .

  In addition, ion exchange membranes (Examples 1, 4, 5, 7, and 9) for fuel cells (PEFC) using hydrogen as a fuel are used as ion exchange membranes of comparative example ion exchange membranes (Comparative Examples 3 to 4). On the other hand, despite the fact that the initial voltages are the same, the durability time is significantly improved, and it is clear that the ion exchange membrane has excellent durability. In addition, it exhibits durability comparable to that of the existing ion exchange membrane Nafion (registered trademark) 112 (Comparative Example 5) and exhibits an initial voltage equal to or higher than that. It is clear that it has sufficiently excellent characteristics as a hydrocarbon ion exchange membrane with a low load. From these facts, the sulfonic acid group-containing polymer of the present invention can greatly improve its characteristics when used in an ion exchange membrane for fuel cells, and contributes greatly to the industry.

The polymer synthesized in Example 1 of the present invention, by using a VARIAN Co. GEMINI-200, is a ¹ H-NMR spectrum was measured at room temperature in deuterated dimethylsulfoxide. The polymer synthesized in Example 2 of the present invention is a ^{1 H-NMR} spectrum was measured in the same manner as described above. The dynamic viscoelastic property of the ion exchange membrane measured using Rheogel E-4000 (made by Toki Sangyo Co., Ltd.) obtained in Example 2 in the present invention is shown.

Explanation of symbols

DMSO: signal derived from dimethyl sulfoxide in deuterated dimethyl sulfoxide H ₂ O: signal derived from water adsorbed on polymer

Claims (16)

A sulfonic acid group-containing polymer having all the structures represented by chemical formulas 1 to 4 as essential repeating units.

[In the chemical formulas 1 to 4, X represents an —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, and Z ^{1 to} Z ² each independently represent Either O or S atom, Ar ¹ is a trivalent aromatic group, Ar ² is a divalent aromatic group having an electron-withdrawing group, and R ¹ is an alkyl group having 2 to 30 carbon atoms. , X represents an integer of 1 to 6, respectively. ] The sulfonic acid group-containing polymer according to claim 1, wherein Ar ¹ is one or more groups selected from structures represented by chemical formulas 5 to 8.

The sulfonic acid group-containing polymer according to claim 2, wherein Ar ¹ has a structure represented by Chemical Formula 5 or 6. The sulfonic acid group-containing polymer according to claim 1 or 2, wherein R ¹ is a linear alkyl group having 4 to 20 carbon atoms. The sulfonic acid group-containing polymer according to any one of claims 1 to 4, wherein Ar ² is one or more groups selected from structures represented by chemical formulas 9 to 12.

The polymer according to claim 5, wherein Ar ² is represented by chemical formula 11 or 12. Z ¹ and Z ² are both O atoms, and the sulfonic acid group-containing polymer according to claim 1. The sulfonic acid group-containing polymer according to any one of claims 1 to 7, wherein X is a -S (= O) _2- group. The repeating structure represented by Chemical Formulas 1 to 4 in the molecule and the molar ratio of the other repeating structures satisfy Formulas 1 to 3, respectively. polymer.

[In the above formula, n1 to n4 represent mol% of the repeating structure represented by chemical formulas 1 to 4 in the molecule, and n5 represents mol% of the other repeating structure, respectively. ]   An ion exchange membrane using the polymer according to claim 1. The ion exchange membrane according to claim 10, wherein n1 to n5 satisfy Formula 4 or 5 and are used for a direct methanol fuel cell.

11. The ion exchange membrane according to claim 10, wherein n1 to n5 satisfy Formula 6 or 7, and are used for a polymer electrolyte fuel cell using hydrogen as a fuel.

  A membrane / electrode assembly using the ion exchange membrane according to any one of claims 10 to 12.   A membrane / electrode assembly, wherein the polymer according to any one of claims 1 to 9 is used for an electrode catalyst layer.   A fuel cell using the membrane / electrode assembly according to claim 13 or 14. A composition comprising the polymer according to claim 1.

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