JP2007063533A - Sulfonic group-containing polymer, use of the same, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion-exchange membrane improved in physical durability and bondability to an electrode catalyst layer, while keeping wettability as it is, to provide a new sulfonic group-containing polymer capable of being used for the same, to provide a membrane/electrode bonded material given by using the ion-exchange membrane and/or the sulfonic group-containing polymer, to provide a fuel cell, and to provide a sulfonic group-containing polymer composition. <P>SOLUTION: This sulfonic group-containing polymer comprises a repeating structure expressed by chemical formula 1. The ion-exchange membrane obtained from the new sulfonic group-containing polymer or the composition thereof has such an excellent effect as to realize the high durability and high output power in comparison with conventional hydrocarbon-based ion-exchange membranes, when used as the fuel cell. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sulfonic acid group-containing polymer having a novel structure, a composition and production method 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, corrosive hydrofluoric acid is mixed into the exhaust gas depending on the use conditions, and the environmental load at the time of disposal is regarded as a problem.

  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 due to water increases, which causes problems such as dimensional change and deterioration of physical properties 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 Japanese Patent Application Laid-Open No. 2004-149779

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

1. A sulfonic acid group-containing polymer mainly composed of a repeating structure represented by the following chemical formula 1.

[In Chemical Formula 1, Ar ¹ represents either Ar ³ or Ar ⁴ , Ar ² represents one or more groups selected from the group consisting of the structures represented by Chemical Formulas 2 to 4 below, and Ar ³ represents electron withdrawing property. A divalent aromatic group having a group, Ar ⁴ is a divalent aromatic group having both an electron-withdrawing group and a sulfonic acid group or a salt or derivative thereof, and Ar ⁵ is represented by the following chemical formula 5. Ar ⁶ is a divalent aromatic group different from Ar ² and Ar ⁵ , Ar ⁷ is either Ar ³ or Ar ⁴ , Z ¹ , Z ² and Z ³ each independently represent an O or S atom. n, m, and p each represents an integer of 1 or more, and o represents an integer of 0 or more. ]

[In Chemical Formula 5, W is one selected from the group consisting 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. In the above groups, q represents an integer of 1 or more. ]

However, in Chemical Formula 1, a unit structure represented by —Z ¹ —Ar ² —Z ¹ —Ar ³ —, a unit structure represented by —Z ¹ —Ar ² —Z ¹ —Ar ⁴ —, —Z ³ — ^Three unit structures of the unit structure represented by Ar ⁶ —Z ³ —Ar ⁷ — may be bonded at random, or a specific unit structure may continuously form a segment. Good.

2. ^2. The sulfonic acid group-containing polymer according to 1 above, wherein Ar ² has a structure represented by Chemical Formula 2.

3. ^3. The sulfonic acid group-containing polymer according to 1 or 2 above, wherein Ar ³ is one or more groups selected from the group consisting of structures represented by the following chemical formulas 6 to 9.

4). 4. The sulfonic acid group-containing polymer according to 3 above, wherein Ar ³ is at least one structure selected from the group consisting of structures represented by chemical formulas 8 or 9.

5. Ar ⁴ is one or more groups selected from the group consisting of structures represented by the following chemical formulas 10 and 11, The sulfonic acid group-containing polymer as described in any one of 1 to 4 above,

[In Chemical Formulas 10 and 11, X represents H or a monovalent cation. ]

6). 6. The sulfonic acid group-containing polymer according to 5 above, wherein Ar ⁴ is a group having a structure represented by Chemical Formula 10.

7). 7. The sulfonic acid group-containing polymer as described in any one of 1 to 6 above, wherein Ar ⁶ is a group having a structure represented by the following chemical formula 12.

8). W is one or more groups selected from the group consisting of an O atom, an S atom, and a —C (CF ₃ ) ₂ — group. polymer.

9. Z ¹ and Z ³ are O atoms, The sulfonic acid group-containing polymer as described in any one of 1 to 8 above.

10. Sulfonic acid group-containing polymer according to any one of the above 1 to 9, wherein the Z ² is S atom.

11. Ar ² is a structure represented by Chemical Formula 2, Ar ³ is a structure represented by Chemical Formula 9, Ar ⁴ is a structure represented by Chemical Formula 10, W is an O or S atom, Ar ⁶ Is a structure represented by Chemical Formula 12, wherein Z ¹ and Z ³ are both O atoms, and Z ² is either an O or S atom. polymer.

12 12. The sulfonic acid group-containing polymer as described in 11 above, wherein W is an O atom, and an average value of q is 3 or more.

13. n, m, o satisfy | fills following numerical formula, The sulfonic acid group containing polymer in any one of said 1-12 characterized by the above-mentioned.

14 14. The sulfonic acid group-containing polymer as described in 13 above, wherein n, m and o satisfy the following mathematical formula.

15. 15. The sulfonic acid group-containing polymer as described in 14 above, wherein n, m and o satisfy the following mathematical formula.

16. 16. An ion exchange membrane using the sulfonic acid group-containing polymer according to any one of 1 to 15 above.

17. 17. A membrane / electrode assembly using the ion exchange membrane according to 16 above.

18. A membrane / electrode assembly, wherein the sulfonic acid group-containing polymer according to any one of 1 to 15 is used for an electrode catalyst layer.

19. 19. A fuel cell using the membrane / electrode assembly according to 17 or 18 above.

20. The composition containing the sulfonic acid group containing polymer in any one of said 1-15.

21. (A) a unit structure represented by Ar ¹ , —Z ¹ —Ar ² —Z ¹ —Ar ³ —, a unit structure represented by —Z ¹ —Ar ² —Z ¹ —Ar ⁴ —, active A step of synthesizing an oligomer containing a unit structure represented by —Z ³ —Ar ⁶ —Z ³ —Ar ⁷ — as an essential component and an end group, and (B) an active end group of the oligomer The method for producing a sulfonic acid group-containing polymer as described in any one of 1 to 15 above, which comprises a step of reacting a compound having a terminal group capable of reacting with a structure represented by the chemical formula 5 together with the compound.

  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 compared to conventional hydrocarbon ion-exchange membranes. It has an excellent effect.

  Hereinafter, the present invention will be described in detail.

Ar ² in Chemical Formula 1 showing the structure of the sulfonic acid group-containing polymer of the present invention is a group represented by Chemical Formulas 2-4. It is preferable that Ar ² has the structure of Chemical Formula 2 because the swelling property of the polymer is suppressed and excellent physical properties are exhibited even during moisture absorption. It is preferable that Ar ² has the structure of Chemical Formula 3 because the glass transition temperature is increased and the heat resistance is improved. It is preferable that Ar ² has the structure of Chemical Formula 4 because brittleness when molded can be reduced. Among the chemical formulas 2 to 4, the chemical formula 2 is most preferable because it generally shows good characteristics.

Ar ³ is a divalent 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 ³ is preferably one or more groups selected from structures represented by Chemical Formulas 6 to 9. The structure of Chemical Formula 6 is preferable because the solubility in a solvent is increased. Moreover, since it becomes possible to provide photocrosslinkability to a polymer, it is preferable that it is a structure of Chemical formula 7. Further, the structure of Chemical Formula 8 or 9 is preferable because the swelling property of the polymer becomes small. Among the following chemical formulas 6 to 9, the structure of chemical formula 8 or 9 is preferable, and the structure of chemical formula 9 is most preferable.

Ar ⁴ is a divalent aromatic group having both an electron-withdrawing group and a sulfonic acid group or a salt or derivative thereof. 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. The sulfonic acid group may be a free acid, or may be a salt with a monovalent cation such as an alkali metal ion such as Na, K or Li, an ammonium ion or a quaternary amine salt, Derivatives such as ester, amide, sulfonimide, acid anhydride, and acid halide may be used. When used as an ionomer for an ion exchange membrane or an electrode catalyst layer of a fuel cell, a free sulfonic acid is preferable from the viewpoint of proton conductivity, and the free sulfonic acid in all sulfonic acid groups is 80 mol% or more. More preferably, it is more preferable in it being 90 mol%. Examples of Ar ⁴ include groups in which sulfonic acid groups are introduced into the structures represented by Chemical Formulas 6 to 9. A structure derived from Chemical Formula 6 is preferable because solubility in a solvent is increased. In addition, the structure derived from Chemical Formula 7 is preferable because the polymer can be imparted with photocrosslinkability. Specifically, one or more groups selected from the group consisting of structures represented by Chemical Formula 10 or 11 are preferable because they exhibit excellent proton conductivity. A structure represented by Chemical Formula 10 is preferable because solubility in a solvent is increased. In addition, the structure represented by the chemical formula 11 is preferable because the polymer can be provided with photocrosslinkability. Among them, the structure represented by the chemical formula 10 is more preferable because it exhibits excellent characteristics in heat resistance, proton conductivity, and the like.

  In Chemical Formula 10 or 11, X represents H or a monovalent cation, but when used as an ion exchange membrane of a fuel cell, X is preferably H. Further, in processing such as dissolution, molding, and film formation, it is preferable that X 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 an ion exchange resin or an ion exchange membrane. Among them, the ion 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.

Ar ⁵ represents one or more groups selected from the group represented by Chemical Formula 5. W in Chemical Formula 5 is one or more selected from the group consisting of O atom, S atom, —C (CH ₃ ) ₂ — group, —C (CF ₃ ) ₂ — group, —CH ₂ — group, and cyclohexyl group. A group is preferably an O atom, an S atom, or a —C (CF ₃ ) ₂ — group, because it improves bondability and is excellent in durability, and is more preferably an O or S atom. S atoms are preferred and most preferred. q may be 1 or more. When W is an O atom, the value of q may be two or more, but an average value of 3 or more is preferable because the bondability is further improved.

Z ¹ , Z ² , and Z ³ each independently represent an O or S atom, but an S atom is preferable because oxidation resistance is improved. O atoms are more preferable because the monomer used as a raw material for the polymer has low toxicity and is easily available. In terms of ease of synthesis and durability, Z ¹ and Z ³ are each preferably an O atom, and more preferably Z ² is an S atom.

Ar ⁶ represents a divalent aromatic group different from Ar ² and Ar ⁵ . Ar ⁶ may have a heteroaromatic group such as a benzazole group, a pyridine ring, or a triazine ring in addition to the benzene ring. Moreover, you may have polar groups, such as a cyano group and a hydroxy group. Ar ⁶ having a structure represented by Chemical Formula 12 is preferable because durability is improved. Or it is preferable that it contains a phosphonic acid group, a phosphoric acid group, etc. because oxidation resistance improves. 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. Specific examples of Ar ⁶ include structures represented by chemical formulas 13A to 13E, but are not limited thereto.

(In the formula, R represents a methyl group, r represents an integer of 0 to 2, and s represents an integer of 1 or more.)

In Chemical Formula 1, a unit structure represented by —Z ¹ —Ar ² —Z ¹ —Ar ³ —, a unit structure represented by —Z ¹ —Ar ² —Z ¹ —Ar ⁴ —, —Z ³ —Ar ⁶ Each of the three unit structures of the unit structure represented by —Z ³ —Ar ⁷ — may be bonded at random, or a specific unit structure may continuously form a segment. The unit structure represented by Z ¹ -Ar ² -Z ¹ -Ar ³ -and the unit structure represented by -Z ¹ -Ar ² -Z ¹ -Ar ^4- are essential, but -Z ³ -Ar ⁶ -Z ³ -Ar ⁷ - unit structure represented by may be omitted. It is preferable that they are all bonded at random, because they are excellent in swelling resistance and durability.

  When n, m, and o in Chemical Formula 1 satisfy Formulas 1 and 2, an ion exchange membrane having favorable characteristics in proton conductivity, swelling resistance, bondability, and the like can be obtained. Furthermore, it is more preferable that n, m, and o satisfy Equation 3 because the balance between swelling resistance and bondability can be achieved. When n + m + o is less than 2, the swelling property tends to increase, and although it has bonding properties, it is not preferable because methanol permeability increases or durability decreases. When n + m + o is larger than 1000, the effect of improving the bonding property becomes extremely small, which is not preferable.

  When the ion exchange membrane of the present invention is used as an ion exchange membrane of a direct methanol fuel cell, it is preferable that n and m satisfy Formula 5.

  As m / (n + m) decreases, methanol permeability decreases, but proton conductivity also decreases. When it increases, proton conductivity improves, but methanol permeability also increases. An excellent fuel cell can be obtained by selecting n and m according to the purpose in consideration of the concentration and capacity of the aqueous methanol solution used. If it is less than 0.1, sufficient proton conductivity cannot be obtained, and the output of the fuel cell becomes low. If it is more than 0.5, the amount of methanol passing through the membrane becomes too large, and the output of the fuel cell decreases. This is not preferable. A more preferable range is 0.1 to 0.4. In addition, when the concentration of the aqueous methanol solution used as the fuel is low, the higher m / (n + m), the higher the proton conductivity, and the higher the output of the fuel cell. On the other hand, when a high-concentration methanol aqueous solution is used, a smaller m / (n + m) can suppress a decrease in output due to the permeation of methanol, and can increase the output of the fuel cell.

  When the ion exchange membrane of the present invention is used as an ion exchange membrane of a fuel cell using hydrogen as a fuel, it is preferable that n and m satisfy Expression 6.

  As m / (n + m) decreases, the swellability decreases, but the proton conductivity also decreases, and when it increases, the proton conductivity improves, but the swellability also increases. When the value of m / (n + m) is smaller than 0.3, sufficient proton conductivity cannot be obtained, and the output of the fuel cell is lowered, which is not preferable. If it is larger than 0.7, the swelling property of the film becomes too large, and breakage and output decrease are likely to occur. A more preferable range of m / (n + m) is 0.35 to 0.7, and a more preferable range is 0.4 to 0.5. An excellent fuel cell can be obtained by selecting n and m according to the purpose.

  Although p should just be an integer greater than or equal to 1, It is preferable that it is the range of 3-1000, More preferably, it is the range of 5-1000. If it is 3 or less, the molecular weight of the polymer becomes small, and the physical properties of the ion exchange membrane may be lowered. On the other hand, when the molecular weight is 1000 or more, the molecular weight of the polymer becomes too large, and the viscosity of the solution becomes extremely high, which makes handling difficult. As will be described later, the molecular weight of the polymer can be controlled in an appropriate range by the logarithmic viscosity of the diluted solution.

In the sulfonic acid group-containing polymer of the present invention, the unit structure represented by —Z ³ —Ar ⁶ —Z ³ —Ar ⁷ — is not essential, and o may be 0, but durability, crosslinkability, physical properties the purpose of such properties ^{improve, -Z 3 -Ar 6 -Z 3 -Ar} 7 - unit structure represented by may be incorporated. In that case, it is preferable that n, m, and o satisfy Expression 4 because the balance of characteristics is excellent. A more preferable range is a range represented by Formula 7.

  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 an ion 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.

  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, the sulfonic acid group is preferably an acid type. 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 14A to 14AR, which are representative examples of preferred structures, are shown below, but the scope of the present invention is not limited to the following. In the following formula, q ′ represents an integer of 3 or more.

  Among the chemical formulas 14A to 14AC, the chemical formulas 14A to 14P are preferable because of excellent proton conductivity and swelling resistance, the chemical formulas 14A, 14D, 14G, 14I, 14L, and 14O are more preferable, and the chemical formulas 14A, 14D, and 14G are more preferable. Chemical formula 14A is most preferred. Moreover, since it is the structure represented by Chemical formula 14V-14AA, since the oxidation resistance of a polymer improves, it is preferable. In addition, the structure represented by the chemical formula 14AB or 14AC is preferable because the polymer has crosslinkability and an ion exchange membrane with low swelling property can be obtained.

  The sulfonic acid group-containing polymer of the present invention can be synthesized by any known method. For example, at least two halogen elements or nitro groups activated by an electron-withdrawing group are included in one molecule. And a compound having at least one selected from the group consisting of a bisphenol compound, a bisthiophenol compound, a bisphenol compound derivative, and a bisthiophenol compound derivative in a polar aprotic solvent as necessary. Polymerization can be carried out by aromatic nucleophilic substitution reaction by adding a basic substance and heating.

The sulfonic acid group-containing polymer of the present invention includes (A) a unit structure represented by Ar ¹ , —Z ¹ —Ar ² —Z ¹ —Ar ³ —, —Z ¹ —Ar ² —Z ¹ —Ar ⁴ — A step of synthesizing an oligomer containing a unit structure represented by —Z ³ —Ar ⁶ —Z ³ —Ar ⁷ — as necessary with a unit structure represented by the formula: (B) It can be obtained by a method comprising a step of reacting a compound having an end group capable of reacting with an active end group of the oligomer together with a structure represented by Chemical Formula 5. ^{Specifically,} each of the monomers comprising the structure of Ar ^2, Ar 3, Ar ^4, the total number of moles of Ar ³ and Ar ⁴ are reacted as becomes excessive relative to the Ar ^2, halogen or nitro A sulfonic acid group-containing polymer of the present invention is obtained by synthesizing an oligomer at the terminal end and reacting a monomer having a hydroxy group or a mercapto group with the structure of Chemical Formula 5 therein. The oligomer may be used after being purified and isolated after the reaction, or may be further reacted by adding a monomer having a hydroxy group or a mercapto group to the structure of Chemical Formula 5 in the reaction solution.

  The sulfonic acid group is preferably introduced in advance into any of the above monomers from the viewpoint of reactivity.

  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.

  Examples of compounds having at least two halogen elements or nitro groups activated by an electron-withdrawing group in one molecule and having no sulfonic acid group include 4,4′-dichlorodiphenylsulfone, 4,4 '-Dichlorobenzophenone, 4,4'-dichlorodiphenylphosphine oxide, 4,4'-bis (4-chlorophenylsulfonyl) biphenyl, 2,6-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2,6-dichloro -1-trifluoromethylbenzene, 2,4-dichloro-1-trifluoromethylbenzene, 4,4′-difluorodiphenylsulfone, 4,4′-difluorobenzophenone, 4,4′-difluorodiphenylphosphine oxide, 4, 4′-bis (4-fluorophenylsulfonyl) biphenyl 2,6-difluorobenzonitrile, 2,4-difluorobenzonitrile, 2,6-difluoro-1-trifluoromethylbenzene, 2,4-difluoro-1-trifluoromethylbenzene, decafluorobiphenyl and the like. Without being limited thereto, other aromatic dihalogen compounds, aromatic dinitro compounds, aromatic dicyano compounds and the like that are active in aromatic nucleophilic substitution reactions can also be used. Among them, 4,4′-dichlorodiphenyl sulfone, 4,4′-difluorodiphenyl sulfone, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile, 4,4′-dichlorobenzophenone, 4,4′-difluoro Benzophenone is preferable, and 2,6-dichlorobenzonitrile and 2,6-difluorobenzonitrile are more preferable.

  Examples of compounds having two halogen elements or nitro groups activated by an electron-withdrawing group in one molecule and having a sulfonic acid group include 3,3′-disulfo-4,4′-dichlorodiphenylsulfone, 3,3′-disulfo-4,4′-difluorodiphenyl sulfone, 3,3′-disulfo-4,4′-dichlorobenzophenone, 3,3′-disulfo-4,4′-difluorobenzophenone, and sulfones thereof Examples include those in which the acid group is converted to a salt with a monovalent cation species. Examples of monovalent cation species include sodium, potassium, lithium, other metal species, various amines, and the like. Sodium, potassium, and the like are preferable, but are not limited thereto. Preferred examples include sodium 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone, sodium 3,3′-disulfonate-4,4′-difluorodiphenylsulfone, sodium 3,3′-disulfonate-4. , 4′-dichlorobenzophenone, 3,3′-sodium disulfonate-4,4′-difluorobenzophenone, 3,3′-sodium disulfonate-4,4′-dichlorodiphenylsulfone, 3,3 '-Disulfonic acid sodium-4,4'-difluorodiphenylsulfone is more preferred.

Examples of the bisphenol compound or bisthiophenol compound that forms Ar ² of Formula 1 include 1,3-bis (4-hydroxy) adamantane, 4,4′-biphenol, 9,9-bis (4-hydroxyphenyl) fluorene, 4,4′-dimercaptobiphenyl can be used, and 4,4′-biphenol is preferred.

Examples of the bisphenol compound or bisthiophenol compound forming Ar ⁵ of Formula 1 include 4,4′-thiobisbenzenethiol, bis (4-hydroxyphenyl) sulfide, 4,4′-dihydroxydiphenyl ether, 4,4′- Dihydroxydiphenylmethane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 1,1-bis (4-hydroxyphenyl) cyclohexane and the like can be used, 4,4′-thiobisbenzenethiol, bis (4-hydroxyphenyl) sulfide, 4,4′-dihydroxydiphenyl ether, and 2,2-bis (4-hydroxyphenyl) hexafluoropropane are more preferable, and 4,4′- Thiobisbenzenethiol, bis (4- More preferred is hydroxyphenyl) sulfide. The polymer structure derived from these monomers has the effect of increasing the flexibility of the polymer, making it difficult to break against deformation and increasing durability, and the effect of increasing the bondability with the electrode by lowering the glass transition temperature. ing.

Examples of the bisphenol compound or bisthiophenol compound forming Ar ^{6 of} Chemical Formula 1 include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (3-methyl-4-hydroxyphenyl) fluorene, 9-bis (4-mercaptophenyl) fluorene, 9,9-bis (3-methyl-4-mercaptosiphenyl) fluorene, 4,4′-biphenol, 4,4′-dimercaptobiphenyl, bis (4-hydroxy Phenyl) 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, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, hydroquinone, resorcin, 1,4-dimercaptobenzene, 1,3-dimercaptobenzene, bis (4-hydroxyphenyl) ketone, 4,4′-thiobisbenzenethiol, 4,4′-thiodiphenol, 3-methyl-4,4′-dihydroxy-p-terphenyl, 4,4′-dihydroxy-p-terphenyl, 1,3 -Bis (4-hydroxy) adamantane, 2,2-bis (4-hydroxy) adamanta Can be used naphthalene bisphenols, 10- (2,5-dihydroxyphenyl) -9,10-dihydro-9-oxa-10-phosphatonin phenanthrene-10-oxide, and diallyl Bisphenol A.

  When the sulfonic acid group-containing polymer in the present invention is polymerized by an aromatic nucleophilic substitution reaction, the above aromatic dihalogen compound is reacted with a bisphenol compound or bisthiophenol compound in the presence of a basic compound. Coalescence can be obtained. The polymerization degree of the resulting polymer can be adjusted by adjusting 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. 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, and is preferably from 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.

  In addition, 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, 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 ion exchange capacity of the sulfonic acid group-containing polymer in the present invention is preferably 0.1 meq / g or more, 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 preferable range is 0.5 to 3.5 meq / g, and a further preferable range is 0.6 to 2.2 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 whole 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.

  Further, it can be combined with various porous materials, fiber materials, fine particles, etc. to form an ion exchange membrane.

  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, it is preferable to distill off the solvent 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 if necessary, it is converted to a free sulfonic acid group by acid treatment. You can also.

  The most preferable method for forming an ion exchange membrane from the sulfonic acid group-containing polymer and the resin composition thereof in the present invention is a cast from a solution, and the ion exchange membrane is obtained by removing the solvent from the cast solution as described above. 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 obtained by bonding the ion exchange 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, an adhesive is applied to the electrode surface to bond the ion exchange membrane and the electrode, or an ion exchange membrane and the electrode. There is a method of heating and pressurizing. Among these, the method of applying and bonding an adhesive mainly composed of the sulfonic acid group-containing polymer and the resin composition thereof to the electrode surface is preferred. This is because the adhesion between the ion exchange membrane and the electrode is improved, and it is considered that the proton conductivity of the ion exchange membrane is less impaired.

  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 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. 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.

Electricity 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. By sandwiching the ion exchange membrane between the gas diffusion layers with the electrode catalyst layer so that the electrode catalyst layer is in contact with the membrane, and pressurizing and heating at 130 ° C. and 2.5 MPa for 3 minutes by a hot press method, A membrane-electrode assembly was obtained. The joined body was incorporated into 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.

Electricity 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 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. A membrane sample is sandwiched between the above two types of carbon paper with an electrode catalyst layer so that the electrode catalyst layer is in contact with the membrane sample, and heated and pressurized at 180 ° C. and 10 MPa for 3 minutes by a hot press method. -It was set as the electrode assembly. 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: The weight of a sample dried at 100 ° C. for 1 hour and allowed to stand overnight at room temperature in a nitrogen atmosphere was measured. After stirring with an aqueous sodium hydroxide solution, the ion exchange capacity was determined by back titration with an aqueous hydrochloric acid solution. .

Softening temperature: While heating an acid-type film having a width of 5 mm at a chuck width of 10 mm from 50 ° C. to 250 ° C. at a rate of 2 ° C./min, a dynamic strain of 10 Hz was applied to give dynamic viscoelasticity, Rhegel E-4000 ( Measured using Toki Sangyo Co., Ltd. The temperature at the inflection point at which E ′ greatly decreased when the temperature was raised was defined as the deformation temperature.

<Example 1>
Sodium 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone (abbreviation: S-DCDPS) 6.2332 g (12.69 mmol), 2,6-dichlorobenzonitrile (abbreviation: DCBN) 8.7302 g (50 .75 mol), 4,4′-biphenol (abbreviation: BP) 10.3222 g (57.10 mmol), potassium carbonate 9.6452 g (69.79 mmol), 80 ml of N-methyl-2-pyrrolidone (abbreviation: NMP). Weighed into a 200 ml four-necked flask equipped with a Dean-Stark trap, nitrogen inlet tube, and stirrer. The flask was placed in an oil bath, stirred and heated while flowing nitrogen, and after removing water distilled together with NMP at 190 ° C. for 30 minutes, the Dean-Stark trap was removed and refluxed with a condenser tube. Was raised to 200 ° C. and reacted for 8 hours. Thereafter, a solution prepared by dissolving 1.3848 g (6.34 mmol) of bis (4-hydroxyphenyl) sulfide (abbreviation: BPS) in 10 ml of NMP was added dropwise little by little and stirred well, and then at 200 ° C. for another 8 hours. Reacted. Thereafter, the reaction solution was allowed to cool, and the reaction solution was precipitated in water in the form of a strand. The obtained polymer was washed twice in boiling water for 1 hour, and then the solid content was filtered with a glass filter and dried in an inert oven at 100 ° C. The logarithmic viscosity of the polymer was 0.84 dL / g. The ¹ H-NMR spectrum measured at room temperature in deuterated dimethyl sulfoxide is shown in FIG. 7 g of polymer was dissolved in 28 g of NMP, cast on a glass plate on a hot plate to a thickness of about 400 μm, heated at 80 ° C. for 0.5 hour, 120 ° C. for 0.5 hour, and 150 ° C. for 0.5 hour, and then nitrogen atmosphere Was dried in an oven at 150 ° C. for 1 hour, and the film was peeled off 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. Thereafter, the film was washed with pure water until the washing water became neutral, and allowed to stand in the air and dried to obtain an ion exchange membrane. The obtained ion exchange membrane was evaluated.

<Example 2>
Example 4 except that 4.6054 g (18.39 mmol) of 4,4′-thiobisbenzenethiol (abbreviation: TBT) was used instead of BPS, and the amount of BP was changed to 9.7472 g (52.35 mmol). In the same manner, an ion exchange membrane was prepared and evaluated.

<Example 3>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 except that the amounts of S-DCDPS, DCBN, BPS, and BP were changed.

<Example 4>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 3 except that 2,2-bis (4-hydroxyphenyl) propane (abbreviation: BPA) was used instead of BPS.

<Example 5>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 3 except that 2,2-bis (4-hydroxyphenyl) hexafluoropropane (abbreviation: BPF) was used instead of BPS.

<Example 6>
The amount of S-DCDPS, DCBN, BPS, BP was changed, and 10- (2,5-dihydroxyphenyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (abbreviation: DHP) The ion exchange membrane was prepared and evaluated in the same manner as in Example 1 except that the above was added.

<Example 7>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 3 except that 1,1-bis (4-hydroxyphenyl) cyclohexane (abbreviation: BPH) was used instead of BPS.

<Comparative Example 1>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 1 except that BPS was reacted from the beginning.

<Comparative example 2>
An ion exchange membrane was prepared and evaluated in the same manner as in Example 3 except that BPS was reacted from the beginning.

<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 15 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 16 having a known structure.

<Comparative Example 5>
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 17 having a known structure.

<Comparative Example 6>
Various evaluations were performed on Nafion (registered trademark) 112, which is a commercially available ion exchange membrane.

<Comparative Example 7>
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 membrane (Examples 1 and 2) for the direct methanol fuel cell (DMFC) in the present invention has a softening temperature compared to the ion exchange membranes of the comparative examples (Comparative Examples 1 and 3). It is clear that the bondability is improved by lowering and the high output voltage is obtained by lowering the resistance value. In particular, although Example 1 and Comparative Example 1 have the same polymer composition, the effect of improving the bonding property can be achieved even if the amount of BPS copolymerization is small due to the specific higher order structure obtained by the production method of the present invention. It has come out greatly and shows the superior point of the present invention. In addition, for Nafion (registered trademark) 117 (Comparative Example 7), which is an existing ion exchange membrane, methanol permeability is significantly small, methanol permeability resistance is excellent, and output as a fuel cell is high. It is clear that it is an excellent ion exchange membrane.

  In addition, the ion exchange membranes (Examples 3 to 7) for the fuel cell (PEFC) using hydrogen as a fuel are initially compared to the ion exchange membranes of the comparative example (Comparative Examples 2 and 4 to 5). The voltage is slightly improved and the durability time is greatly improved, and it is clear that the ion exchange membrane has excellent durability. In particular, although Example 3 and Comparative Example 2 have the same polymer composition, the effect of improving durability can be achieved even with a small amount of copolymerized BPS due to the specific higher order structure obtained by the production method of the present invention. It has come out greatly and shows the superior point of the present invention. In addition, since it shows durability comparable to the existing ion exchange membrane Nafion (registered trademark) 112 (Comparative Example 6), and shows an initial voltage equal to or higher than that, there is little generation of corrosive substances such as hydrofluoric acid, In addition, it is clear that it has sufficiently excellent characteristics as a hydrocarbon-based ion exchange membrane with a low environmental load at the time of disposal. 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.

It is the ¹ H-NMR spectrum which measured the polymer synthesize | combined in Example 6 in this invention like the above.

The dynamic viscoelastic property of the ion exchange membrane measured using Rheogel E-4000 (made by Toki Sangyo Co., Ltd.) obtained in Example 1 in the present invention is shown.

Explanation of symbols

NMP: signal derived from N-methyl-2-pyrrolidone which is a polymerization solvent contained as an impurity in the polymer DMSO: signal derived from dimethyl sulfoxide in deuterated dimethyl sulfoxide H ₂ O: in water adsorbed on the polymer Originating signal

Claims (21)

A sulfonic acid group-containing polymer mainly composed of a repeating structure represented by the following chemical formula 1.

[In Chemical Formula 1, Ar ¹ represents either Ar ³ or Ar ⁴ , Ar ² represents one or more groups selected from the group consisting of the structures represented by Chemical Formulas 2 to 4 below, and Ar ³ represents electron withdrawing property. A divalent aromatic group having a group, Ar ⁴ is a divalent aromatic group having both an electron-withdrawing group and a sulfonic acid group or a salt or derivative thereof, and Ar ⁵ is represented by the following chemical formula 5. Ar ⁶ is a divalent aromatic group different from Ar ² , Ar ⁷ is either Ar ³ or Ar ⁴ , Z ¹ , Z ² , Z Each ³ independently represents an O or S atom. n, m, and p each represents an integer of 1 or more, and o represents an integer of 0 or more. ]

[In Chemical Formula 5, W is one selected from the group consisting 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. In the above groups, q represents an integer of 1 or more. ]
However, in Chemical Formula 1, a unit structure represented by —Z ¹ —Ar ² —Z ¹ —Ar ³ —, a unit structure represented by —Z ¹ —Ar ² —Z ¹ —Ar ⁴ —, —Z ³ — ^Three unit structures of the unit structure represented by Ar ⁶ —Z ³ —Ar ⁷ — may be bonded at random, or a specific unit structure may continuously form a segment. Good. The sulfonic acid group-containing polymer according to claim 1, wherein Ar ² has a structure represented by Chemical Formula 2. The sulfonic acid group-containing polymer according to claim 1 or 2, wherein Ar ³ is one or more groups selected from the group consisting of structures represented by the following chemical formulas 6 to 9.

4. The sulfonic acid group-containing polymer according to claim 3, wherein Ar ³ is at least one structure selected from the group consisting of structures represented by Chemical Formula 8 or 9. The sulfonic acid group-containing polymer according to any one of claims 1 to 4, wherein Ar ⁴ is at least one group selected from the group consisting of structures represented by the following chemical formulas 10 and 11.

[In Chemical Formulas 10 and 11, X represents H or a monovalent cation. ] The sulfonic acid group-containing polymer according to claim 5, wherein Ar ⁴ is a group having a structure represented by Chemical Formula 10. The sulfonic acid group-containing polymer according to any one of claims 1 to 6, wherein Ar ⁶ is a group having a structure represented by the following chemical formula 12.

W is, O atom, S atom, -C (CF ₃₎ 2 _- sulfonic acid group according to claim 1, characterized in that the one or more groups selected from the group consisting of group Containing polymer. Z ¹ and Z ³ are O atoms, The sulfonic acid group-containing polymer according to claim 1. Sulfonic acid group-containing polymer according to any one of claims 1 to 9 Z ² is characterized in that it is a S atom. Ar ² is a structure represented by Chemical Formula 2, Ar ³ is a structure represented by Chemical Formula 9, Ar ⁴ is a structure represented by Chemical Formula 10, W is an O or S atom, Ar ⁶ Is a structure represented by the chemical formula 12, Z ¹ and Z ³ are both O atoms, and Z ² is either an O or S atom. Containing polymer.   The sulfonic acid group-containing polymer according to claim 11, wherein W is an O atom, and an average value of q is 3 or more. n, m, and o satisfy | fill the following numerical formula, The sulfonic acid group containing polymer in any one of Claims 1-12 characterized by the above-mentioned.

14. The sulfonic acid group-containing polymer according to claim 13, wherein n, m, and o satisfy the following mathematical formula.

The sulfonic acid group-containing polymer according to claim 14, wherein n, m, and o satisfy the following mathematical formula.

  An ion exchange membrane using the sulfonic acid group-containing polymer according to any one of claims 1 to 15.   A membrane / electrode assembly using the ion exchange membrane according to claim 16.   A membrane / electrode assembly, wherein the polymer according to any one of claims 1 to 15 is used for an electrode catalyst layer.   A fuel cell using the membrane / electrode assembly according to claim 17 or 18.   The composition containing the sulfonic acid group containing polymer in any one of Claims 1-15. (A) a unit structure represented by Ar ¹ , —Z ¹ —Ar ² —Z ¹ —Ar ³ —, a unit structure represented by —Z ¹ —Ar ² —Z ¹ —Ar ⁴ —, active A step of synthesizing an oligomer containing a unit structure represented by —Z ³ —Ar ⁶ —Z ³ —Ar ⁷ — as an essential component and an end group, and (B) an active end group of the oligomer The method for producing a sulfonic acid group-containing polymer according to any one of claims 1 to 15, further comprising a step of reacting a compound having a terminal group capable of reacting with a structure represented by Chemical Formula 5 together with the compound represented by Chemical Formula 5.

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