Electrolyte material, liquid composition and membrane/electrode assembly for polymer electrolyte fuel cell

1. An electrolyte material, which comprises a polymer (H) having ion exchange groups converted from precursor groups in the following polymer (F), and having an ion exchange capacity of at least 1.35 meq/g dry resin:

polymer (F): a polymer which has repeating units (A) based on a perfluoromonomer having a precursor group of an ion exchange group and a dioxolane ring and repeating units (B) based on a perfluoromonomer having no ion exchange group nor its precursor group and having a dioxolane ring, and which has a TQ as defined below of at least 200° C.:

TQ: a temperature at which the melt volume rate becomes 100 mm 3 /sec, when the polymer (F) is subjected to melt extrusion under an extrusion pressure condition of 2.94 MPa from a nozzle having a length of 1 mm and an inner diameter of 1 mm.

2. The electrolyte material according to claim 1 , wherein the ion exchange groups in the polymer (H) are groups represented by the following formula (g1):

—(SO 2 X(SO 2 R f ) a ) 31 M +   (g1)

wherein M + is H + , a monovalent metal cation or an ammonium ion in which at least one hydrogen atom may be substituted by a hydrocarbon group, R f is a linear or branched perfluoroalkyl group which optionally has an etheric oxygen atom, and X is an oxygen atom, a nitrogen atom or a carbon atom, provided that when X is an oxygen atom, a=0, when X is a nitrogen atom, a=1, and when X is a carbon atom, a=2.

3. The electrolyte material according to claim 2 , wherein at least one type of repeating units having ion exchange groups converted from the precursor groups in the repeating units (A) are repeating units represented by the following formula (u1):

wherein R 1 is a bivalent perfluoroorganic group which optionally has an etheric oxygen atom, and each of R 2 to R 6 which are independent of one another, is a monovalent perfluoroorganic group which optionally has an etheric oxygen atom, or a fluorine atom.

4. The electrolyte material according to claim 3 , wherein R 5 and R 6 are a fluorine atom.

5. The electrolyte material according to any one of claims 2 to 4 , wherein M + is H + .

6. The electrolyte material according to claim 3 , wherein at least one type of the repeating units represented by the formula (u1) are repeating units represented by the following formula (u1-1):

7. The electrolyte material according to claim 1 , wherein at least one type of the repeating units (B) are repeating units represented by the following formula (u2):

wherein each of R 7 to R 12 which are independent of one another, is a monovalent perfluoroorganic group which optionally has an etheric oxygen atom, or a fluorine atom.

8. The electrolyte material according to claim 7 , wherein at least one type of the repeating units represented by the formula (u2) are repeating units represented by the following formula (u2-1):

9. A liquid composition comprising a dispersion medium and the electrolyte material as defined in claim 1 dispersed in the dispersion medium, wherein the dispersion medium contains an organic solvent having a hydroxy group.

10. A membrane/electrode assembly for a polymer electrolyte fuel cell, which comprises an anode having a catalyst layer containing a proton conductive polymer, a cathode having a catalyst layer containing a proton conductive polymer, and a polymer electrolyte membrane disposed between the anode and the cathode, wherein the proton conductive polymer contained in the catalyst layer of at least one of the cathode and the anode is the electrolyte material as defined in claim 1 .

11. The electrolyte material according to claim 1 , wherein the ion exchange capacity is from 1.5 to 3.8 meq/g dry resin.

12. The electrolyte material according to claim 1 , wherein TQ is at least 230° C.

13. The electrolyte material according to claim 1 , wherein TQ is at least 250° C.