JP5470674B2 - Polymer electrolyte membrane, polymer electrolyte membrane / electrode assembly, fuel cell, and fuel cell operating method - Google Patents

Description

  The present invention relates to a polymer electrolyte membrane suitable for a fuel cell operating without humidification, an electrolyte membrane / electrode assembly and a fuel cell using the polymer electrolyte membrane, and a non-humidification of a fuel cell using the fuel cell. It relates to the driving method.

    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 polymer electrolyte membrane is usually used. As such a polymer 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.

  A polymer electrolyte membrane having a sulfonic acid group as a proton carrier, such as a perfluorocarbon sulfonic acid polymer electrolyte membrane, requires water for proton conduction. Therefore, the membrane is always kept in a hygroscopic state by humidifying the supply gas or by water produced by the reaction. In order to humidify the supply gas, a device for that purpose is required. Therefore, in order to simplify the power generation system, it is desirable that power can be generated without humidification.

  As a method for measuring the moisture absorption state of a polymer electrolyte membrane during power generation in a fuel cell, analysis by MRI is known (see, for example, Patent Documents 1 and 2). However, it has not been clarified what kind of moisture absorption characteristics a polymer electrolyte membrane suitable for non-humidified power generation operation shows during power generation.

JP 2004-170297 A JP 2005-071676 A

  The present invention has been made against the background of the problems of the prior art, and is a polymer electrolyte membrane suitable for a fuel cell operating without humidification power generation, an electrolyte membrane / electrode assembly and a fuel cell using the polymer electrolyte membrane, and An object of the present invention is to provide a non-humidified operation method of a fuel cell using the fuel cell.

  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 polymer electrolyte membrane measured using a spin echo method by MRI when power is generated using unhumidified hydrogen and oxygen in a solid polymer fuel cell using the polymer electrolyte membrane. A polymer electrolyte membrane characterized in that the signal intensity of water in the molecular electrolyte membrane satisfies Formula 1.

(In Equation 1, I ₀ represents the signal strength of water at a current density of 0 A / cm ² , and I _0.3 represents the signal strength of water at a current density of 0.3 A / cm ^2. )

2. 2. The polymer electrolyte membrane according to 1 above, wherein the polymer electrolyte membrane is mainly composed of a hydrocarbon polymer.

3. 2. The polymer electrolyte membrane according to 1 above, wherein the ion exchange capacity is in the range of 2 to 4 meq / g.

4. Conductivity at 80 ° C. and relative humidity 95% is 0.2 S / cm or more, and conductivity at 0.0 ° C. and relative humidity 50% is 0.010 S / cm or more. Polymer electrolyte membrane.

5. The polymer electrolyte membrane according to 1 above, which does not dissolve in water at 80 ° C.

6). The sulfonic acid group is contained, and is mainly composed of an aromatic polymer in which at least one of polysulfone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfide sulfone, and polyether ketone is copolymerized. 1. The polymer electrolyte membrane according to 1.

7). 2. The polymer electrolyte membrane according to claim 1, wherein the polymer electrolyte membrane is mainly composed of an aromatic polymer having a structure represented by the following chemical formula 1 in the molecule.

[In Chemical Formula 1, X represents an —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, Z ¹ represents either an O or S atom, Ar represents a divalent aromatic group. ]

8). 8. The polymer electrolyte membrane according to 7 above, wherein Ar has a structure represented by the following chemical formula 2.

[In Chemical Formula 2, Z ² represents any of an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, and a cyclohexyl group, and n 1 represents Represents an integer of 0 or more. ]

9. 9. The polymer electrolyte membrane as described in 8 above, wherein Z ¹ and Z ² are both O atoms, and n1 is 3 or more.

10. 8. The polymer electrolyte membrane according to 7 above, further comprising a structure represented by chemical formula 3.

[In Chemical Formula 3, Ar ¹ and Ar ′ represent a divalent aromatic group, and Z ³ represents either O or S atom. ]

11. 11. The polymer electrolyte membrane as described in 10 above, wherein Ar ′ has a structure represented by the following chemical formula 4.

[In Chemical Formula 4, Z ⁴ represents an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, or a cyclohexyl group, and n 2 represents Represents an integer of 0 or more. ]

12 12. The polymer electrolyte membrane as described in 11 above, wherein Z ³ and Z ⁴ are both O atoms, and n2 is 3 or more.

13. 11. The polymer electrolyte membrane as described in 10 above, wherein Ar ¹ is one or more groups selected from structures represented by the following chemical formulas 5 to 8.

14 14. The polymer electrolyte membrane as described in 13 above, wherein Ar ¹ has a structure represented by chemical formula 8.

15. 8. The polymer electrolyte membrane according to 7 above, wherein Ar has a structure represented by any one of the following chemical formulas 9A to 9G.

(In the formula, R represents an alkyl group having 1 to 4 carbon atoms, and r represents an integer of 0 to 2).

16. 16. The polymer electrolyte membrane as described in 15 above, wherein Ar has a structure represented by the following chemical formula 10.

17. 11. The polymer electrolyte membrane according to 10 above, wherein Ar ′ has a structure represented by any one of chemical formulas 9A to 9G.

18. 18. The polymer electrolyte membrane according to 17 above, wherein Ar ′ has a structure represented by chemical formula 10.

19. 11. The polymer electrolyte membrane according to 10 above, wherein Ar and Ar ′ are structures represented by chemical formula 10, and Ar ¹ is a structure represented by chemical formula (8).

20. 20. The polymer electrolyte membrane as described in 19 above, wherein X is a —S (═O) ₂ — group, Y is an H atom, and Z ¹ and Z ³ are O atoms.

21. 11. The polymer electrolyte membrane according to the above item 10, wherein the mol% of the structure represented by the chemical formula 1 and the chemical formula 3 satisfies the following mathematical formula 2.

(In the above formula, n3 represents mol% of the structure represented by Chemical Formula 1, and n4 represents mol% of the structure represented by Chemical Formula 3, respectively.)

22. 9. The polymer electrolyte membrane according to 8 above, further having a structure represented by the following chemical formula 11.

[In Chemical Formula 11, X represents a —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, and Z ⁵ represents either an O or S atom. . ]

23. 12. The polymer electrolyte membrane according to 11 above, further having a structure represented by chemical formula 12.

[In the chemical formula 12, Ar ² represents a divalent aromatic group, and Z ⁶ represents either O or S atom. ]

24. 24. The polymer electrolyte membrane as described in 23 above, wherein Ar ² is one or more groups selected from structures represented by chemical formulas 5 to 8.

25. 25. The polymer electrolyte membrane as described in 24 above, wherein Ar ² has a structure represented by chemical formula 8.

26. 23. The polymer electrolyte membrane as described in 22 above, wherein Z ¹ and Z ² are O or S atoms, and n1 is 1.

27. 24. The polymer electrolyte membrane as described in 23 above, wherein Z ³ and Z ⁴ are O or S atoms, and n2 is 1.

28. (A) At least 4 of Chemical Formula 1 in which Ar is a structure represented by Chemical Formula 2, (B) Chemical Formula 3 in which Ar ′ is a structure represented by Chemical Formula 4, (C) Chemical Formula 11, and (D) Chemical Formula 12. It has a repeating unit represented by a kind of structure, and the mole% of each repeating unit and the mole% of other repeating structures are mainly composed of an aromatic polymer satisfying Formulas 3 to 5. 2. The polymer electrolyte membrane according to 1 above.

(In the above formula, n5 represents the mol% of the structure represented by the chemical formula 11, n6 represents the mol% of the structure represented by the chemical formula 1 where Ar is the structure represented by the chemical formula 2, and n7 represents the chemical formula 12. N8 represents the mol% of the structure represented by the chemical formula 3 in which Ar ′ is the structure represented by the chemical formula 4, and n9 represents the mol% of the other repeating structure.)

29. 29. An electrolyte membrane / electrode assembly using the polymer electrolyte membrane according to any one of 1 to 28 above.

30. 30. A fuel cell using the electrolyte membrane / electrode assembly according to 29.

31. 31. A non-humidified operation method for a polymer electrolyte fuel cell, characterized by using the fuel cell as described in 30 above.

  The polymer electrolyte membrane of the present invention is superior in power generation characteristics without humidification compared to existing perfluorocarbon sulfonic acid polymer electrolyte membranes. When used as a fuel cell, the polymer electrolyte membrane has a higher output with a simpler system. Can be obtained.

Hereinafter, the present invention will be described in detail.
The polymer electrolyte membrane of the present invention was measured using a spin echo method by MRI when power was generated using non-humidified hydrogen and oxygen in a solid polymer fuel cell using the polymer electrolyte membrane. The signal strength of water in the polymer electrolyte membrane satisfies the formula 1. The measurement can be performed by installing the fuel battery cell in the MRI measurement apparatus. The nuclide to be measured is ¹ H (hydrogen), and a spin echo method can be used as a sequence for acquiring an image. In the spin echo method, the echo time, repetition time, number of times of image averaging, slice thickness, and image acquisition range can be appropriately set depending on the size, thickness, shape, measurement purpose, etc. of the sample to be measured.

The signal intensity of water is obtained as a signal intensity of ¹ H, and can be obtained as a relative value by placing a reference substance in the measurement cell. This allows comparison between different samples.

  The non-humidified power generation is preferably performed in the range of 5 to 90 ° C. However, since the output may decrease as the temperature increases, the range of 10 to 80 ° C is more preferable, and the range of 20 to 60 ° C is further preferable. preferable.

The moisture content of the polymer electrolyte membrane during non-humidified power generation is preferably increased as the current density increases. The current density when the current density is 0.3 A / cm ² is 0 A / cm. The range of 1.5 to 10 times that of cm ² is preferable, and the range of 2 to 4 times is more preferable. If it is less than 1.5 times, it is not preferable because power cannot be generated up to a high current density, or the output voltage is low, resulting in low output. If it is larger than 10 times, it is preferable in terms of output, but it is not preferable because the swelling property of the film becomes too large and the durability becomes poor.

  Since the polymer electrolyte membrane of the present invention requires a high water content, it is preferable to use a hydrocarbon-based polymer electrolyte membrane into which more ionic groups can be introduced. The hydrocarbon-based polymer electrolyte membrane may be partially fluorinated in the polymer structure, but is not perfluorinated, aromatic or aliphatic repeating units, sulfonic acid or phosphonic acid, It represents a polymer electrolyte membrane mainly composed of a polymer composed of an ionic group such as phosphoric acid.

  The polymer constituting the polymer electrolyte membrane is preferably an aromatic polymer, and an aromatic polymer obtained by copolymerizing at least one of polysulfone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfide sulfone, and polyether ketone. It is preferably mainly composed of a polymer.

  Specific examples of the polymer constituting the polymer electrolyte membrane include polyarylene, polyarylene ether, polyarylene sulfide, polyarylene ether sulfide, polyarylene ether nitrile, polyarylene ether nitrile sulfide, polysulfone, polyethersulfone, poly Heat-resistant polymers such as phenylsulfone, polyetherketone, polyetheretherketone, polyimide, polybenzazole, polyetherimide, polyamide, and polyamideimide can be mentioned as preferred examples, but are not limited thereto.

  Among them, polyarylene ether, polyarylene sulfide, polyarylene ether sulfide, polyarylene ether nitrile, polyarylene ether nitrile sulfide, polysulfone, polyethersulfone, polyphenylsulfone, polyetherketone, polyetheretherketone are more preferable examples. It can be mentioned, but is not limited to these.

  By introducing an ionic group such as a sulfonic acid group, a phosphonic acid group, a phosphoric acid group, or a sulfonimide group into the polymer as described above, it can be used as a proton conductive polymer. The ionic group is preferably a sulfonic acid group because proton conductivity is increased. The amount of ionic groups in the polymer electrolyte membrane may be in the range of 1 to 10 meq / g, more preferably in the range of 2 to 4 meq / g, and in the range of 2.3 to 3 meq / g. More preferably it is. When the ion exchange capacity is large, proton conductivity increases, but swelling property also increases and stability tends to decrease. When the ion exchange capacity is small, proton conductivity is lowered and sufficient performance cannot be obtained.

  The polymer electrolyte membrane of the present invention may be composed only of the proton conductive polymer as described above, or may be a composite membrane with an organic or inorganic porous material, fibril, nonwoven fabric, filler or the like. It may also be a blend with an aprotic conductive polymer. Alternatively, it may be a blend with a proton conductive polymer having a different structure or a laminated film. Furthermore, you may have bridge | crosslinking between proton conductive polymers, or between a proton conductive polymer and a crosslinking agent.

  The polymer electrolyte membrane of the present invention desirably has high proton conductivity. Specifically, the conductivity at 80 ° C. and relative humidity 95% is 0.2 S / cm or more, and 80 ° C. and relative humidity 50 The conductivity at 0.0% is preferably 0.010 S / cm or more, the conductivity at 80 ° C. and 95% relative humidity is 0.3 S / cm or more, and the conductivity at 80 ° C. and 50% relative humidity is 0.015 S / cm. More preferably, it is cm or more.

  The polymer electrolyte membrane of the present invention is preferably not so swellable, but for example, a polymer electrolyte membrane that does not dissolve in water at 80 ° C. provides more preferable results.

  One of the preferred embodiments of the polymer constituting the polymer electrolyte of the present invention is an aromatic polymer having a structure represented by the following chemical formula 1.

[In Chemical Formula 1, X represents an —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, Z ¹ represents either an O or S atom, Ar represents a divalent aromatic group. ]

X is preferably a —S (═O) ₂ — group because solubility in a solvent is improved. It is preferable that X is a —C (═O) — group because the softening temperature of the polymer can be lowered to enhance the bonding property with the electrode, or the photocrosslinking property can be imparted to the electrolyte membrane. When used as a polymer electrolyte membrane, Y is preferably an H atom. However, if Y is an H atom, it is easily decomposed by heat or the like. Therefore, during processing such as manufacturing of an electrolyte membrane, Y is set as an alkali metal salt such as Na or K, and Y is converted to H atom by acid treatment after processing. A polymer electrolyte membrane can also be obtained by conversion. Z ¹ is preferably O since it has advantages such as less coloring of the polymer and easy availability of raw materials. Z ¹ is preferably S because oxidation resistance is improved.

  Ar is a divalent aromatic group, but may be any known group. Among these, Ar is preferably a structure represented by the following chemical formula 2, which can improve the proton conductivity of the polymer electrolyte membrane and the bondability with the electrode, the power generation output when used in a fuel cell, and the like. .

[In Chemical Formula 2, X represents a —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, Z ¹ represents either an O or S atom, Z ² represents an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group or a cyclohexyl group, and n1 represents an integer of 0 or more. Represent. ]

Z ² is preferably O, because it has advantages such as less coloring of the polymer and easy availability of raw materials. Z ² is preferably S because oxidation resistance is improved. It is preferable that n1 is 3 or more because there is an effect of lowering the softening point of the polymer electrolyte membrane, and the bonding property with the electrode is improved. When n1 is 1, Z ² is preferably an O atom, an S atom, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, or a cyclohexyl group, and preferably an O atom or an S atom. More preferred.

In the case where Ar in Chemical Formula 1 has a structure represented by Chemical Formula 2, if Z ¹ and Z ² are both O atoms and n1 is 3 or more, a polymer having good bondability with an electrode An electrolyte membrane is preferred.

  Ar may have a structure represented by any one of the following chemical formulas 9A to 9G. Among them, the structure of chemical formula 9A is preferable, and the structure of chemical formula 10 is more preferable. R is preferably a methyl group. r is preferably 0 because it is easy to obtain a high molecular weight polymer. When r is 1 or 2, it is possible to impart crosslinkability to the polymer, which is preferable.

(In the formula, R represents an alkyl group having 1 to 4 carbon atoms, and r represents an integer of 0 to 2).

  One of preferred embodiments of the polymer constituting the polymer electrolyte of the present invention is an aromatic polymer having a structure represented by the following chemical formula 3 together with a structure represented by the chemical formula 1.

[In Chemical Formula 3, Ar ¹ and Ar ′ represent a divalent aromatic group, and Z ³ represents either O or S atom. ]

Ar ¹ is preferably a divalent aromatic group having an electron-withdrawing group. Examples of the electron-withdrawing group include a sulfone group, a sulfonyl group, a sulfonic acid group, a sulfonic acid ester group, a sulfonic acid amide group, a sulfonic acid imide group, a carboxyl group, a carbonyl group, a carboxylic acid ester group, a cyano group, a halogen group, Although a trifluoromethyl group, a nitro group, etc. can be mentioned, it is not limited to these, What is necessary is just a well-known arbitrary electron withdrawing group.

A preferred structure of Ar ¹ is a structure represented by the following chemical formulas 5-8. The structure of Chemical Formula 5 is preferable because it can increase the solubility of the polymer. The structure of Chemical Formula 6 is preferable because it lowers the softening temperature of the polymer to increase the bonding property with the electrode and impart photocrosslinking properties. The structure of Chemical Formula 7 or 8 is preferable because the swelling of the polymer can be reduced, and the structure of Chemical Formula 8 is more preferable. Among the chemical formulas 5 to 8, the structure of the chemical formula 8 is most preferable.

  Ar ′ is a divalent aromatic group, but may be any known group. Above all, when Ar ′ is a structure represented by the following chemical formula 4, the proton conductivity of the polymer electrolyte membrane and the bondability with the electrode, and the power generation output when used in a fuel cell can be improved. preferable.

[In Chemical Formula 4, Z ⁴ represents an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, or a cyclohexyl group, and n 2 represents Represents an integer of 0 or more. ]

Z ⁴ is preferably O, because it has advantages such as less coloring of the polymer and easy availability of raw materials. Z ⁴ is preferably S because oxidation resistance is improved. It is preferable that n2 is 3 or more because there is an effect of lowering the softening point of the polymer electrolyte membrane, and the bonding property with the electrode is improved. When n2 is 1, Z ⁴ is preferably an O atom, an S atom, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, or a cyclohexyl group, and preferably an O atom or an S atom. More preferred.

In the case where Ar ′ in the chemical formula 3 is a structure represented by the chemical formula 4, when Z ³ and Z ⁴ are both O atoms and n2 is 3 or more, the bonding property with the electrode is excellent. A molecular electrolyte membrane is preferred.

  Ar ′ may have a structure represented by any one of the following chemical formulas 9A to 9G. Among them, the structure of chemical formula 9A is preferable, and the structure of chemical formula 10 is more preferable. R is preferably a methyl group. r is preferably 0 because it is easy to obtain a high molecular weight polymer. When r is 1 or 2, it is possible to impart crosslinkability to the polymer, which is preferable.

(In the formula, R represents an alkyl group having 1 to 4 carbon atoms, and r represents an integer of 0 to 2).

In the above embodiment, it is preferable that Ar and Ar ′ have a structure represented by Chemical Formula 10 and Ar ¹ has a structure represented by Chemical Formula 8 because a polymer electrolyte membrane having excellent proton conductivity and low swellability is obtained. . In addition, it is more preferable that X is a —S (═O) ₂ — group, Y is an H atom, and Z ¹ and Z ³ are O atoms because the characteristics are further improved.

  In the above aspect, the mol% of the structure represented by Chemical Formula 1 and Chemical Formula 3 preferably satisfies the following Numerical Formula 2.

(In the above formula, n3 represents mol% of the structure represented by Chemical Formula 1, and n4 represents mol% of the structure represented by Chemical Formula 3, respectively.)

  [N3 / (n3 + n4)] is more preferably in the range of 0.4 to 0.7, and still more preferably in the range of 0.5 to 0.7. If it is smaller than 0.3, the proton conductivity of the polymer electrolyte membrane is lowered, and the output of the fuel cell tends to be lowered. Moreover, when larger than 0.7, the swelling property of a polymer electrolyte membrane may become remarkably large, and it may become easy to break.

  One of preferred embodiments of the polymer constituting the polymer electrolyte of the present invention is a polymer further having a structure represented by the following chemical formula 11 together with a structure represented by the chemical formula 1 in which Ar is a structure represented by the chemical formula 2. It is. The structure represented by the chemical formula 11 has a function of imparting proton conductivity to the polymer electrolyte membrane and suppressing swelling of the polymer electrolyte membrane.

[In Chemical Formula 11, X represents a —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, and Z ⁵ represents either an O or S atom. . ]

X is preferably a —S (═O) ₂ — group because solubility in a solvent is improved. It is preferable that X is a —C (═O) — group because the softening temperature of the polymer can be lowered to enhance the bonding property with the electrode, or the photocrosslinking property can be imparted to the electrolyte membrane. When used as a polymer electrolyte membrane, Y is preferably an H atom. However, if Y is an H atom, it is easily decomposed by heat or the like. Therefore, during processing such as manufacturing of an electrolyte membrane, Y is set as an alkali metal salt such as Na or K, and Y is converted to H atom by acid treatment after processing. A polymer electrolyte membrane can also be obtained by conversion. Z ⁵ is preferably O, because there are advantages such as little polymer coloring and easy availability of raw materials. Z ⁵ is preferably S because oxidation resistance is improved.

In the above aspect, it is preferable that Z ¹ and Z ² are O or S atoms and n1 is 1, since proton conductivity, bondability with an electrode, and swelling resistance can be improved.

  One of preferred embodiments of the polymer constituting the polymer electrolyte of the present invention includes a structure represented by the chemical formula 1 and a structure represented by the chemical formula 3 in which Ar ′ is a structure represented by the chemical formula 4, It is a polymer further having a structure represented by the following chemical formula 12. The structure represented by Chemical Formula 12 has a function of suppressing the swelling of the polymer electrolyte membrane. .

[In the chemical formula 12, Ar ² represents a divalent aromatic group, and Z ⁶ represents either O or S atom. ]

Ar ² is preferably a divalent aromatic group having an electron-withdrawing group. Examples of the electron-withdrawing group include a sulfone group, a sulfonyl group, a sulfonic acid group, a sulfonic acid ester group, a sulfonic acid amide group, a sulfonic acid imide group, a carboxyl group, a carbonyl group, a carboxylic acid ester group, a cyano group, a halogen group, Although a trifluoromethyl group, a nitro group, etc. can be mentioned, it is not limited to these, What is necessary is just a well-known arbitrary electron withdrawing group.

A preferred structure of Ar ² is a structure represented by the following chemical formulas 5-8. The structure of Chemical Formula 5 is preferable because it can increase the solubility of the polymer. The structure of Chemical Formula 6 is preferable because it lowers the softening temperature of the polymer to increase the bonding property with the electrode and impart photocrosslinking properties. The structure of Chemical Formula 7 or 8 is preferable because the swelling of the polymer can be reduced, and the structure of Chemical Formula 8 is more preferable. Among the chemical formulas 5 to 8, the structure of the chemical formula 8 is most preferable.

In the above aspect, it is preferable that Z ³ and Z ⁴ are O or S atoms and n2 is 1, since proton conductivity, bondability with an electrode, and swelling resistance can be improved.

  One of the preferred embodiments of the polymer constituting the polymer electrolyte of the present invention is a structure in which (A) Ar is a structure represented by Chemical Formula 2 and (B) Ar ′ is a structure represented by Chemical Formula 4. Chemical formula 3, (C) Chemical formula 11 and (D) Chemical formula 12 have repeating units represented by at least four types of structures, and the molar% of each repeating unit and the molar% of other repeating structures are represented by formula 3. It is an aromatic polymer satisfying ˜5.

(In the above formula, n5 represents the mol% of the structure represented by the chemical formula 11, n6 represents the mol% of the structure represented by the chemical formula 1 where Ar is the structure represented by the chemical formula 2, and n7 represents the chemical formula 12. N8 represents the mol% of the structure represented by the chemical formula 3 in which Ar ′ is the structure represented by the chemical formula 4, and n9 represents the mol% of the other repeating structure.)

(N5 + n6 + n7 + n8) / (n5 + n6 + n7 + n8 + n9) is preferably in the range of 0.95 to 1.0. (N5 + n6) / (n5 + n6 + n7 + n8) is more preferably in the range of 0.4 to 0.7, and still more preferably in the range of 0.5 to 0.7. If it is less than 0.3, the proton conductivity may decrease, and the output of the fuel cell may decrease. If it is greater than 0.7, the swelling property of the film increases and problems such as breakage may occur. (N6 + n8) / (n5 + n6 + n7 + n8) is preferably in the range of 0.01 to 0.30, and more preferably in the range of 5 to 20. If it is less than 0.01, the effect of improving the bonding property with the electrode may not be obtained. If it is larger than 0.95, the swelling property of the film may become too large.

  The polymer electrolyte membrane of the present invention can also be obtained from a composition in which the above polymer is dissolved and dispersed in an appropriate solvent. 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.

  The proton conductive polymer constituting the polymer electrolyte membrane of the present invention is, for example, an aromatic dihalogen compound or aromatic dinitro compound activated with an electron-withdrawing group and a bisphenol compound and / or bisthiophenol compound. It can be polymerized by group nucleophilic substitution reactions.

  Among aromatic dihalogen compounds activated with an electron-withdrawing group, those having an ionic group include 3,3′-disulfo-4,4′-dichlorodiphenylsulfone, 3,3′-disulfo-4, 4'-difluorodiphenyl sulfone, 3,3'-disulfo-4,4'-dichlorodiphenyl ketone, 3,3'-disulfo-4,4'-difluorodiphenyl sulfone, 3,3'-dialkylsulfo-4,4 '-Dichlorodiphenylsulfone, 3,3'-dialkylsulfo-4,4'-difluorodiphenylsulfone, 3,3'-dialkylsulfo-4,4'-dichlorodiphenylketone, 3,3'-dialkylsulfo-4, Examples thereof include 4′-difluorodiphenyl sulfone, and those obtained by converting the sulfonic acid group into 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 in which the sulfonic acid group is a salt include sodium 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone, sodium 3,3′-disulfonate-4,4′-difluorodiphenylsulfone. 3,3′-sodium disulfonate-4,4′-dichlorodiphenyl ketone, 3,3′-sodium 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, potassium 3,3′-disulfonate 4,4 '-Dichlorodiphenyl ketone, potassium 3,3'-disulfonate 4,4'-difluorodi Examples include phenyl sulfone, potassium 3,3′-disulfonate 4,4′-difluorodiphenyl ketone, and sodium 3,3′-disulfonate-4,4′-dichlorodiphenyl sulfone, 3,3′-disulfone. Sodium acid-4,4′-difluorodiphenylsulfone is preferred.

  The activated aromatic dihalogen compound containing no ionic group includes 2,6-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2,6-difluorobenzonitrile, 2,4-difluorobenzonitrile, 4, Examples include 4′-dichlorodiphenyl sulfone, 4,4′-difluorodiphenyl sulfone, 4,4′-difluorobenzophenone, 4,4′-dichlorobenzophenone, decafluorobiphenyl, and the like, but are not limited thereto. Other aromatic dihalogen compounds, aromatic dinitro compounds, aromatic dicyano compounds and the like that are active in nucleophilic substitution reactions can also be used. Among these, 2,6-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2,6-difluorobenzonitrile, 2,4-difluorobenzonitrile, 2,6-dichlorobenzonitrile, 2,6 are preferable. -Difluorobenzonitrile is more preferred.

  Examples of the bisphenol compound or bisthiophenol compound include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (3-methyl-4-hydroxyphenyl) fluorene, 4,4′-biphenol, 4 , 4'-dimercaptobiphenyl, bis (4-hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) Methane, 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, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4-hexyl resorcinol, 2,2-bis (4-hydroxyphenyl) Hexafluoropropane, hydroquinone, resorcin, bis (4-hydroxyphenyl) ketone, 4,4′-thiodiphenol, 4,4′-oxydiphenol, 1,3-bis (4-hydroxyphenyl) adamantane, 2, 2-bis (4-hydroxyphenyl) adamantane, 4,4′-thiobisbenzenethiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 10- (2,5-dihydroxyphenyl) -9,10- Dihydro-9-oxa-10-phosphaphenant -10-oxide, polyphenylene ethers having hydroxy groups at both ends, and the like. In addition, various aromatic diols or aromatics that can be used for polymerization of polyarylene ether compounds by aromatic nucleophilic substitution reaction. Group dithiols can also be used and are not limited to the above compounds. Preferred examples among the compounds used in combination include 4,4′-biphenol, 9,9-bis (4-hydroxyphenyl) fluorene, 1,3-bis (4-hydroxyphenyl) adamantane, 4,4′-thiodi. Examples include phenol, 4,4′-oxydiphenol, and 4,4′-thiobisbenzenethiol. When a plurality of types of bisphenol compounds and bisthiophenol compounds are used, it consists of 4,4′-biphenol, 9,9-bis (4-hydroxyphenyl) fluorene, and 1,3-bis (4-hydroxyphenyl) adamantane. One or more compounds selected from the group, 4,4′-thiodiphenol, 4,4′-oxydiphenol, 4,4′-thiobisbenzenethiol, 2,2-bis (4-hydroxyphenyl) hexa Combining one or more compounds selected from the group consisting of fluoropropane, 2,2-bis (4-hydroxyphenyl) propane, 4,4′-dihydroxydiphenylmethane, 1-bis (4-hydroxyphenyl) cyclohexane, The bondability and durability of the polymer electrolyte membrane can be improved, which is preferable.

  When the proton conducting polymer constituting the polymer electrolyte membrane in the present invention is polymerized by an aromatic nucleophilic substitution reaction, an activated aromatic dihalogen compound or activated dinitroaromatic compound and a bisphenol compound or bisthiophenol compound are added. The polymer can be obtained by reacting in the presence of a basic compound. By setting the molar ratio of the reactive halogen group or nitro group to the reactive hydroxy group or mercapto 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.

  In the above polymerization reaction, a bisphenol compound or bisthiophenol compound is reacted with an isocyanate compound such as phenyl isocyanate to carbamoylate without using a basic compound, and an activated dihalogen aromatic compound or dinitro aromatic compound. The compound can also be reacted directly.

  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 bisphenol compound, the bisthiophenol compound and the bisthiophenol compound, and preferably 105 to bisphenol compound and bisthiophenol. The range is 125 mol%. An excessive amount of the basic compound is not preferable because it causes side reactions such as decomposition.

  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.

  Examples of polymer structures that can be used in the polymer electrolyte membrane of the present invention are shown below, but are not limited thereto, and other known polymers can also be used. Among these polymer electrolyte membranes using polymers, spin-echo method by MRI when power is generated using non-humidified hydrogen and oxygen in a solid polymer fuel cell using the polymer electrolyte membrane In the polymer electrolyte membrane of the present invention, the signal intensity of water in the polymer electrolyte membrane measured by using the above satisfies Equation 1.

  In addition, the proton conductive polymer constituting the polymer electrolyte membrane in the present invention preferably has a logarithmic viscosity of 0.1 dL / g or more measured by a method described later. When the logarithmic viscosity is less than 0.1 dL / g, the membrane tends to become brittle when molded as a polymer electrolyte membrane. The logarithmic viscosity is more preferably 0.3 dL / g or more. On the other hand, when 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 polymer electrolyte membrane in the present invention can have any thickness, but if it is 10 μm or less, it becomes difficult to satisfy the predetermined characteristics, and therefore 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 polymer electrolyte membrane of the present invention may be a mixture of the sulfonic acid group-containing polymer as described above, a simple substance, and another polymer. 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 Heat 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. In the polymer electrolyte membrane of the present invention, the proton conductive polymer is preferably contained in an amount of 50% by mass or more and less than 100% by mass with respect to the entire resin composition. More preferably, it is 70 mass% or more and less than 100 mass%. When the content of the proton conductive polymer is less than 50% by weight of the entire resin composition, the sulfonic acid group concentration of the polymer electrolyte membrane containing this resin composition tends to be low and good ion conductivity tends not to be obtained. In addition, the unit containing a sulfonic acid group becomes a discontinuous phase and the mobility of ions to be conducted tends to decrease. 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 proton conductive polymer can be dissolved in a suitable solvent to form a solution composition. Examples of the solvent include aprotic polar solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone and hexamethylphosphonamide, and alcohols such as methanol and ethanol. An appropriate one can be selected, but is not limited thereto. A plurality of these solvents may be used as a mixture within a possible range. The compound concentration in the solution is preferably in the range of 0.1 to 50% by weight. If the concentration of the compound in the solution is less than 0.1% by weight, it tends to be difficult to obtain a good molded product, and if it exceeds 50% by weight, the workability tends to deteriorate.

  The polymer electrolyte membrane of the present invention can be obtained from the composition containing the proton conductive polymer 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 the polymer electrolyte membrane in the present invention from the proton conductive polymer or the composition thereof is casting from a solution, and the polymer is removed from the cast solution by removing the solvent as described above. An electrolyte 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 in view of the uniformity of the polymer electrolyte 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 less than 10 μm, the form as a polymer electrolyte membrane tends to be not maintained, and if it is more 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 a polymer electrolyte 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 electrolyte membrane / electrode assembly of the present invention can be obtained by bonding the polymer electrolyte membrane of the present invention to an electrode. As a method for producing this joined body, a conventionally known method can be used. For example, a method of applying an adhesive to the electrode surface and bonding the polymer electrolyte membrane and the electrode, or a polymer electrolyte membrane and the electrode There is a method of heating and pressurizing. Among these, a method in which an adhesive mainly composed of the same proton conductive polymer as the proton conductive polymer constituting the polymer electrolyte membrane and its resin composition is applied to the electrode surface and adhered is preferable. This is because the adhesion between the polymer electrolyte membrane and the electrode is improved, and it is considered that the proton conductivity of the polymer electrolyte membrane is less impaired. In that case, X in the above chemical formula is preferably H, and the sulfonic acid group is preferably 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 fuel cell of the present invention can be produced using the polymer electrolyte membrane or the electrolyte membrane / electrode assembly of the present invention. The polymer electrolyte membrane of the present invention is suitable for a polymer electrolyte fuel cell that operates without humidification. The fuel cell of the present invention includes, for example, an oxygen electrode, a fuel electrode, the polymer electrolyte membrane of the present invention disposed between the electrodes, an oxidant flow path provided on the oxygen electrode side, a fuel It has a fuel flow path provided on the pole side. A fuel cell stack can be obtained by connecting such unit cells with a conductive separator.

  The non-humidified operation of the fuel cell in the present invention represents an operation in which power is generated by supplying the fuel cell without supplying the fuel or oxidant with water. Hydrogen can be used as the fuel. As hydrogen, hydrogen obtained from a cylinder or a storage tank can be used, or hydrogen obtained by reforming city gas, petroleum, or the like can be used. Moreover, oxygen, air, etc. can be used as an oxidizing agent. A fuel cell capable of non-humidifying operation does not require a fuel or oxidizer humidification facility, and a simpler and cheaper fuel cell can be obtained.

  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.

Proton conductivity: Constant temperature of 80 ° C. and relative humidity of 95% or 50% by pressing a platinum wire (diameter: 0.2 mm) on the surface of a strip-shaped membrane sample on a probe for self-made measurement (made of tetrafluoroethylene resin) The sample was held in a humidity chamber, 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]

MRI evaluation: After adding a commercially available 40% Pt catalyst-supporting carbon (Tanaka Kikinzoku Co., Ltd. fuel cell catalyst TEC10V40E), a small amount of ultrapure water and isopropanol to 20% Nafion (registered trademark) manufactured by DuPont, Stir until homogeneous 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, and a gas diffusion layer with an electrode catalyst layer having a size of 20 × 20 mm. Was made. A polymer electrolyte membrane having a size of 30 × 35 mm is left in an environment of 20 ° C. and a relative humidity of 90% for 1 hour, and then the electrode catalyst layer contacts the membrane between the gas diffusion layers with the electrode catalyst layer. Thus, the membrane-electrode assembly was obtained by pressing and heating at 130 ° C. and 2 MPa for 3 minutes by hot pressing. The joined body was sandwiched between a gold-plated copper plate with a gas supply port opened as a current collector plate, and further sandwiched between acrylic resin plates having gas supply paths to form a measurement cell. The measurement cell is placed in the measurement unit of the MRI system of Varian's Unity Inova 300 (static magnetic field strength: 7.05 Tesla, RF coil system 60 mm), and hydrogen and oxygen are supplied to the anode and cathode respectively at a flow rate of 50 ml / min. A power generation test was conducted. The measurement nuclide was ¹ H, and measurement was performed using a spin echo method as an image acquisition sequence. At that time, the echo time is 6 ms, the repetition time is 0.5 s, the number of times of image averaging is 16, the slice thickness is 10 mm, the image acquisition range is 7.68 cm (128 pixels) in the film surface direction, and 1.28 cm in the film thickness direction. (256 pixels). The temperature was room temperature (25 ° C.), and the temperature of the cell part was not particularly adjusted. The relative intensity (I) was calculated by comparing the MRI signal intensity of water in the polymer electrolyte membrane region with the standard substance in the cell.

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.

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).

<Example 1>
40 g of a proton conductive polymer having the structure of the following chemical formula 16 having a logarithmic viscosity of 1.88 dL / g of a 0.5 g / dL N-methyl-2-pyrrolidone solution measured at 30 ° C. using an Ubbelohde viscometer In N-methyl-2-pyrrolidone and filtered through a 200 mesh wire mesh. The resulting solution was left to degas and cast on a glass plate with a thickness of 500 μm. The glass plate was heated from 80 ° C. for 1 hour, 120 ° C. for 30 minutes, and 150 ° C. for 30 minutes, and then dried in an inert oven in a nitrogen atmosphere at 150 ° C. for 1 hour. Then, the film is peeled off from the glass, immersed in 5 L of pure water for 24 hours, then immersed in 5 L of 2M sulfuric acid for 1 hour, and further immersed in new 5 L of 2M sulfuric acid for 1 hour. The paper was washed with paper until neutral, fixed to a metal frame, left in a room at 25 ° C. and dried to obtain a polymer electrolyte membrane having a thickness of 45 μm. MRI evaluation was performed using the obtained polymer electrolyte membrane. The proton conductivity at 80 ° C. and relative humidity of 95 and 66% was 0.51 and 0.017 S / cm, respectively, and the ion exchange capacity was 2.67 meq / g.

<Comparative Example 1>
Evaluation was performed using an existing perfluorocarbon sulfonic acid polymer electrolyte membrane having an ion exchange capacity of 0.9 meq / g and an average thickness of 50 μm. The proton conductivity at 80 ° C. and relative humidity 95 and 66% were 0.19 and 0.009 S / cm, respectively, and the ion exchange capacity was 0.90 meq / g.

  Table 1 shows the MRI evaluation results.

As can be seen from Table 1, it can be seen that the polymer electrolyte membranes of the examples are superior polymer electrolyte membranes because they exhibit higher voltage and higher maximum output than the comparative polymer electrolyte membranes. As can be seen from the measurement result of the MRI signal intensity, the polymer electrolyte membrane of the example has a stronger signal strength of water than the polymer electrolyte membrane of the comparative example, and the signal density with respect to the signal strength at a current density of 0 A / cm ² . Because the polymer electrolyte membrane has a large signal intensity ratio at a current density of 0.3 A / cm ² and retains more water at a high current density, it can secure moisture necessary for proton conduction, and is excellent This shows the power generation characteristics. As described above, the polymer electrolyte membrane of the present invention is useful because it exhibits high output in a fuel cell that operates without humidification, and greatly contributes to the industry.

Claims (26)

It is composed of a hydrocarbon polymer , has an ion exchange capacity in the range of 2 to 4 meq / g, has a conductivity at 80 ° C. and a relative humidity of 95% of 0.2 S / cm or more, and at 80 ° C. and a relative humidity of 50%. According to MRI, when electric power is generated using non-humidified hydrogen and oxygen in a solid polymer fuel cell having a conductivity of 0.010 S / cm or more and a polymer electrolyte membrane that does not dissolve in water at 80 ° C. A fuel cell using a polymer electrolyte membrane in which the signal intensity of water in the polymer electrolyte membrane measured using a spin echo method satisfies Formula 1.
(In Formula 1, I ₀ represents the signal strength of water at a current density of 0 A / cm ² , and I _0.3 represents the signal strength of water at a current density of 0.3 A / cm ^2. ) The polymer electrolyte membrane is an aromatic polymer containing a sulfonic acid group and copolymerized with at least one of polysulfone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfide sulfone, and polyether ketone. The fuel cell according to claim 1, wherein the fuel cell is configured. From an aromatic polymer having a structure represented by the following chemical formula 1 in the molecule The fuel cell according to claim 2, wherein the fuel cell is configured.
[In the chemical formula 1, X is a —S (═O) ₂ — group or —C (═O) — group, Y is H or a monovalent cation, Z ¹ is either an O or S atom, Ar represents a divalent aromatic group. ] The fuel cell according to claim 3, wherein Ar has a structure represented by the following chemical formula 2.
[In Chemical Formula 2, Z ² represents any one of an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group, a cyclohexyl group, and n 1 represents Represents an integer of 0 or more. ] 5. The fuel cell according to claim 4, wherein Z ¹ and Z ² are both O atoms, and n1 is 3 or more. The fuel cell according to claim 5, further comprising a structure represented by Chemical Formula 3.
[In Chemical Formula 3, Ar ¹ and Ar ′ represent a divalent aromatic group, and Z ³ represents either an O or S atom. ] The fuel cell according to claim 6, wherein Ar ′ has a structure represented by the following chemical formula 4.
[In Chemical Formula 4, Z ⁴ represents an O atom, an S atom, a —C (CH ₃ ) ₂ — group, a —C (CF ₃ ) ₂ — group, a —CH ₂ — group or a cyclohexyl group, and n 2 represents Represents an integer of 0 or more. ] The fuel cell according to claim 7, wherein Z ³ and Z ⁴ are both O atoms, and n2 is 3 or more. The fuel cell according to claim 8, wherein Ar ¹ is one or more groups selected from structures represented by the following chemical formulas 5 to 8.
The fuel cell according to claim 9, wherein Ar ¹ has a structure represented by Chemical Formula 8. The fuel cell according to claim 3, wherein Ar has a structure represented by any one of the following chemical formulas 9A to 9G.
(In the formula, R represents an alkyl group having 1 to 4 carbon atoms, and r represents an integer of 0 to 2). The fuel cell according to claim 11, wherein Ar has a structure represented by the following chemical formula 10:
The fuel cell according to claim 6, wherein Ar ′ has a structure represented by any one of chemical formulas 9A to 9G. The fuel cell according to claim 13, wherein Ar ′ has a structure represented by Chemical Formula 10. 7. The fuel cell according to claim 6, wherein Ar and Ar ′ have a structure represented by Chemical Formula 10 and Ar ¹ has a structure represented by Chemical Formula (8). The fuel cell according to claim 15, wherein X is a —S (═O) ₂ — group, Y is an H atom, and Z ¹ and Z ³ are O atoms. The fuel cell according to claim 6, wherein the mol% of the structure represented by Chemical Formula 1 and Chemical Formula 3 satisfies the following Formula 2.
(In the above formula, n3 represents mol% of the structure represented by Chemical Formula 1, and n4 represents mol% of the structure represented by Chemical Formula 3, respectively.) The fuel cell according to claim 7, further comprising a structure represented by the following chemical formula 11:
[In Chemical Formula 11, X represents a —S (═O) ₂ — group or —C (═O) — group, Y represents H or a monovalent cation, and Z ⁵ represents either an O or S atom. . ] The fuel cell according to claim 7, further comprising a structure represented by Chemical Formula 12.
[In Chemical Formula 12, Ar ² represents a divalent aromatic group, and Z ⁶ represents either O or S atom. ] The fuel cell according to claim 19, wherein Ar ² is one or more groups selected from structures represented by chemical formulas 5 to 8. The fuel cell according to claim 20, wherein Ar ² has a structure represented by Chemical Formula 8. 19. The fuel cell according to claim 18, wherein Z ¹ and Z ² are O or S atoms, and n1 is 1. Z ³ and Z ⁴ are the O or S atom, and a fuel cell according to claim 19, characterized in that n2 is 1. (A) At least 4 of Chemical Formula 1 in which Ar is a structure represented by Chemical Formula 2, (B) Chemical Formula 3 in which Ar ′ is a structure represented by Chemical Formula 4, (C) Chemical Formula 11, and (D) Chemical Formula 12. An aromatic polymer having a repeating unit represented by a type of structure, wherein the mol% of each repeating unit and the mol% of other repeating structures satisfy Formulas 3 to 5. The fuel cell according to claim 1, wherein the fuel cell is configured.
(In the above formula, n5 represents the mol% of the structure represented by the chemical formula 11, n6 represents the mol% of the structure represented by the chemical formula 1 where Ar is the structure represented by the chemical formula 2, and n7 represents the chemical formula 12. N8 represents the mol% of the structure represented by the chemical formula 3 in which Ar ′ is the structure represented by the chemical formula 4, and n9 represents the mol% of the other repeating structure.)   The fuel cell according to any one of claims 1 to 24, which is used for a non-humidifying operation.   The fuel cell according to any one of claims 1 to 25, wherein the fuel is hydrogen.