Polymer, electrolyte material, electrolyte membrane, electrolyte membrane with catalyst layer, membrane electrode assembly, polymer electrolyte fuel cell, and polymer electrolyte water electrolysis device

Abstract

This polymer which has a structure represented by formula (1). (In formula (1), A1 represents a constituent unit expressed by formula (a1), A2 represents a constituent unit expressed by formula (a2), L1 and L2 each independently represent a single bond or the like, n represents an integer of 10 to 100, and * represents an atomic bond. There are two or more kinds of A1 and / or A2, the difference in x in formula (a1) among a plurality of A1 moieties is 3 or less, and the difference in y in formula (a2) among a plurality of A2 moieties is 5 or less.) (In formula (a1), IExG represents an ion exchange group, L3 represents a single bond or the like, x represents an integer of 2 to 10, and * represents an atomic bond.) (In formula (a2), Ar represents an arylene group having no ion exchange group, L4 represents a single bond or the like, y represents an integer of 3 to 20, and * represents an atomic bond.)

Description

Polymers, electrolyte materials, electrolyte membranes, electrolyte membranes with catalyst layers, membrane electrode assemblies, polymer electrolyte fuel cells, and polymer electrolyte water electrolyzers.

[0001] This disclosure relates to polymers, electrolyte materials, electrolyte membranes, electrolyte membranes with catalyst layers, membrane electrode assemblies, polymer electrolyte fuel cells, and polymer electrolyte water electrolyzers.

[0002] In recent years, fuel cells have been attracting attention as a highly energy-efficient new energy technology, driven by environmental concerns. Among them, polymer electrolyte fuel cells, which use polymer materials as electrolytes, are particularly noteworthy because they have a high maximum current density and operate at low temperatures, making them suitable as power sources for mobile devices such as automobiles and small-capacity power sources for portable electronic devices.

[0003] Fluorine-based polymers are known as electrolyte polymers used in polymer electrolyte fuel cells and water electrolysis (see, for example, Patent Document 1). Although fluorine-based polymers are widely used in electrolyte applications due to their high proton conductivity and excellent swelling resistance, they have the problems of being expensive and having a large environmental impact.

[0004] For these reasons, the development of electrolyte polymers that do not use fluorine is also progressing. For example, Patent Document 2 discloses an invention relating to a polymer electrolyte membrane made of a block copolymer containing one or more segments (A1) containing ionic groups and one or more segments (A2) that do not contain ionic groups.

[0005] Japanese Patent Publication No. 11-204119, International Publication No. 2013-031675

[0006] However, non-fluorinated polymers obtained by block copolymerization, such as those disclosed in Patent Document 2, do not necessarily possess sufficient proton conductivity.

[0007] One aspect of this disclosure aims to provide a polymer with excellent proton conductivity as an electrolyte.

[0008] The present invention is as described in the claims, and the present disclosure provides, in several aspects, the following [1] to

[14] .

[0009] [1] The following formula (1): [In formula (1), A １ represents the following formula (a1): (In formula (a1), IExG represents an ion exchange group, L ３ represents a single bond, -O-, -S-, -SO ２ -, or -CO-, x represents an integer from 2 to 10, and * represents a bond. A plurality of IExG may be the same or different from each other, and a plurality of L ３ may be the same or different from each other.) represents a structural unit, and A ２ represents the following formula (a2): (In formula (a2), Ar represents an arylene group having no ion exchange group, L ４ represents a single bond, -O-, -S-, -SO ２ -, or -CO-, y represents an integer from 3 to 20, and * represents a bond. A plurality of Ar may be the same or different from each other, and a plurality of L ４ may be the same or different from each other.) represents a structural unit, and L １ and L ２ each independently represent a single bond, -O-, -S-, or -SO ２ -, n represents an integer from 10 to 100, and * represents a bond. A plurality of A １ may be the same or different from each other, a plurality of A ２ may be the same or different from each other, a plurality of L １ may be the same or different from each other, a plurality of L ２ may be the same or different from each other. However, at least one of A １ and A ２ exists in two or more kinds, the difference in x in formula (a1) in a plurality of A １ is within 3, and the difference in y in formula (a2) in a plurality of A ２ is within 5.] A polymer having the structure represented by

[0010] [2] The polymer according to [1], wherein the constituent unit represented by formula (a1) comprises at least one group selected from the group consisting of a sulfonic acid group, an alkyl sulfonic acid group, and a sulfonimide group, and salts thereof, as the ion exchange group.

[0011] [3] The polymer according to [1] or [2], wherein the constituent unit represented by formula (a2) comprises, as the arylene group, at least one group selected from the group consisting of a phenylene group, a naphthylene group, and a fluorene group, which may have a substituent.

[0012] [4] The following formula (b1): [In formula (b1), A １ This is synonymous with the above, X １ｂ and X ２ｂ Each of these independently represents a halogen atom. Compound (b1) represented by ] and the following formula (b2): [In formula (b2), A ２ This is synonymous with the above, Z １ｂ and Z ２ｂ Each independently represents a hydroxyl group, a thiol group, a halogen atom, a boronic acid group, an alkylborane group, or a boronic acid ester group. A polymer with compound (b2) represented by ] (where at least one of compound (b1) and compound (b2) is a plurality of A in formula (1) １ The difference of x in formula (a1) in the above formula becomes 3 or less, and multiple A in formula (1) ２ In the above equation (a2), the difference of y is 5 or less. １ Or A ２ The polymer according to any one of [1] to [3], which includes two or more compounds of different types, or is an oxide of the polymer.

[0013] [5] A polymer according to any one of [1] to [3], comprising a plurality of polymer units including the structure represented by formula (1), and having a crosslinking group that bonds with three or more of the polymer units.

[0014] [6] The polymer according to any one of [1] to [5], wherein the weight-average molecular weight is 40,000 to 500,000.

[0015] [7] Tetramethylsilane is used as the internal standard. １ A polymer according to any one of [1] to [6], having a peak in the range of 6.70 to 6.95 ppm in the 1H-NMR spectrum.

[0016] [8] The polymer according to any one of [1] to [7], wherein the ion exchange capacity is 1.0 to 3.5 mmol / g.

[0017] [9] An electrolyte material containing the polymer described in any of [1] to [8].

[0018]

[10] An electrolyte membrane containing the polymer described in any of [1] to [8].

[0019]

[11] An electrolyte membrane with a catalyst layer, comprising the electrolyte membrane described in

[10] and a catalyst layer disposed on one or both sides of the electrolyte membrane.

[0020]

[12] A membrane electrode assembly comprising an electrolyte membrane as described in

[10] and an electrode layer disposed on one or both sides of the electrolyte membrane.

[0021]

[13] A polymer electrolyte fuel cell comprising the membrane electrode assembly described in

[12] .

[0022]

[14] A solid polymer water electrolysis apparatus comprising the membrane electrode assembly described in

[12] .

[0023] According to one aspect of this disclosure, it is possible to provide a polymer with excellent proton conductivity as an electrolyte.

[0024] Figure 1 is a graph showing the small-angle scattering profile obtained by SAXS measurement of the electrolyte membrane of Example 1.

[0025] The following describes exemplary embodiments of this disclosure. However, this disclosure is not limited to the embodiments described below. In this specification, numerical ranges indicated using "~" indicate a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. Also, unless otherwise explicitly stated, the units of the numerical values ​​before and after "~" are the same. Furthermore, each configuration and parameter disclosed in this specification can be combined in any way, and the upper and lower limits described individually can be combined in any way.

[0026] <Polymer> The polymer of one embodiment (hereinafter also referred to as "polymer (P)") has a structure represented by the following formula (1).

[0027]

[0028] In formula (1), A １ This is a constituent unit represented by the following formula (a1) (hereinafter referred to as "constituent unit A １ It is also called ". ) and A ２ This is a constituent unit represented by the following formula (a2) (hereinafter referred to as "constituent unit A ２ It is also called ". ) indicates L １ and L ２ These are, independently, a single bond, -O-, -S-, or -SO-. ２ - indicates a combination, n is an integer between 10 and 100, and * indicates a combination. Multiple A １ They may be the same or different from each other, and there may be multiple A ２ These may be the same or different from each other, and there may be multiple L １ These may be the same or different from each other, and there may be multiple L ２ They may be the same or different from each other. However, A １ and A ２ At least one of them has two or more types, and multiple A １ The difference of x in equation (a1) in is 3 or less, and multiple A ２ The difference of y in equation (a2) is within 5.

[0029]

[0030] In formula (a1), IExG represents an ion exchange group, and L ３ These are single bonds, -O-, -S-, -SO ２ - or -CO- is indicated, x is an integer from 2 to 10, and * is an association. Multiple IExG may be the same or different from each other, and multiple L ３ They may be the same or different from one another.

[0031]

[0032] In formula (a2), Ar represents an arylene group that does not have an ion exchange group, and L４ These are single bonds, -O-, -S-, -SO ２ - or -CO- is indicated, y is an integer from 3 to 20, and * indicates a combination. Multiple Ars may be the same or different from each other, and multiple L ４ They may be the same or different from one another.

[0033] Polymer (P) is a so-called electrolyte polymer and possesses excellent proton conductivity. Therefore, the film formed by polymer (P) (polymer electrolyte film) exhibits excellent proton conductivity. The reason why polymer (P) has excellent proton conductivity is not clear, but it is presumed to be as follows: Multiple A in polymer (P) １ Since the difference of x in equation (a1) is within 3, multiple hydrophilic constituent units A １ These are identical or have similar molecular sizes, and multiple A ２ Since the difference of y in equation (a2) is within 5, multiple hydrophobic constituent units A ２ These are identical or have similar molecular sizes. In other words, polymer (P) is composed of multiple hydrophilic constituent units A that are identical or have similar molecular sizes. １ (Hydrophilic part) and multiple hydrophobic constituent units A that are identical to or have similar molecular sizes to each other. ２ It has a structure in which the (hydrophobic parts) and are precisely arranged, and the ion exchange groups in polymer (P) are arranged at approximately equal intervals. Therefore, it is presumed that the ion exchange groups self-assemble in a higher-order structure, inducing a microphase separation structure, and that this forms good proton conduction paths within polymer (P). Also, constituent unit A １ The presence of three or more ion exchange groups densely packed together is also presumed to contribute to improved phase separation and proton conductivity. The above effects are particularly pronounced in high-humidity environments (for example, under humidity levels of 80% RH or higher).

[0034] Polymer (P) tends to exhibit excellent gas barrier properties when formed into a film. The reason for this is presumed to be as follows: Because the main chain of polymer (P) is composed of arylene groups containing benzene rings, the solubility of hydrogen and oxygen is low, and segmental motion is restricted, suppressing gas diffusion within the film. Therefore, it is thought to exhibit excellent gas barrier properties when formed into a film.

[0035] (Polymer (P)) As shown in formula (1), polymer (P) is composed of constituent unit A １ and constituent unit A ２ and the linking group (L １ or L ２ The structure has a continuous repeating structure (the structure in brackets in formula (1)) via a ). The number of repeats (n) of the structure is 10 to 100, and may be 15 or more or 20 or more, or 80 or less or 50 or less. When the number of repeats (n) is 15 or more, the gas barrier properties tend to be excellent, and when the number of repeats (n) is 50 or less, the solubility in the solvent and film formation properties tend to be excellent. The number of repeats (n) of the structure is preferably 15 to 80, and more preferably 20 to 50.

[0036] [Construction Unit A] １ ] Component Unit A １ This is an aromatic ring having an ion exchange group (IExG) and a linking group (L ３ It has a continuous structure via ).

[0037] An ion-exchange group is a group that has the property of being able to exchange ions (e.g., cations) with other ions, and is also called an ionic group. Examples of ion-exchange groups include sulfonic acid groups, alkyl sulfonic acid groups, perfluoroalkyl sulfonic acid groups, sulfonimide groups, phosphonic acid groups, phosphate groups, and carboxyl groups, as well as their salts. As mentioned above, ion-exchange groups also include those that form salts with metal ions, etc.

[0038] Sulfonic acid groups and their salts include, for example, -SO ３ M １／ｑ(M represents H or a metal (for example, at least one selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ti, Al, Fe, Pt, Rh, Ru, Ir, and Pd), and q represents the valence of M (for example, an integer from 1 to 4).) The metal represented by M exists as an ion (cation), -SO ３ － It forms salt.

[0039] Alkyl sulfonic acid groups and their salts are, for example, -R １ SO ３ M １／ｑ It is represented by R １ R is an alkanediyl group, and from the viewpoint of obtaining better proton conductivity, its carbon number is preferably 1 to 12 (an integer). １ Specific examples include, for instance, a methylene group, a butane-1,4-diyl group, and a hexane-1,6-diyl group. M and q are as defined above.

[0040] Sulfonimide groups and their salts include, for example, -SO ２ NM １／ｑ SO ２ R ２ It is represented by R ２ R is an alkyl group, and from the viewpoint of obtaining better proton conductivity, its number of carbon atoms is preferably 1 to 6 (an integer). ２ Specific examples include methyl, ethyl, and propyl groups. M and q are the same as above.

[0041] Constituent unit A １ From the viewpoint of obtaining better proton conductivity, it is preferable that the ion exchange group includes at least one group selected from the group consisting of sulfonic acid groups, alkyl sulfonic acid groups, and sulfonimide groups, and salts thereof, and more preferably that it includes at least one group selected from the group consisting of sulfonic acid groups and salts thereof. From a similar viewpoint, constituent unit A １ It is even more preferable that the majority of the multiple ion exchange groups present within are of the above preferred embodiment, and constituent unit A １ It is particularly preferable that all of the multiple ion exchange groups present therein are of the above-described preferred form.

[0042] Structural unit A １ From the viewpoint of obtaining better proton conductivity, as the linking group (L ３ ), it preferably contains at least one group selected from the group consisting of -SO ２ - and -CO-, and more preferably contains -SO ２ -. From the same viewpoint, among the plurality of linking groups (L １ ) present in the structural unit A ３ , it is more preferable that the majority are those in the above preferred embodiment.

[0043] Structural unit A １ The linking group (L ３ ) in is preferably a single bond or -SO ２ - from the viewpoint of improving proton conductivity and chemical durability.

[0044] The linking position of the linking group (L ３ ) is not particularly limited, but from the viewpoint of obtaining better proton conductivity and chemical durability, it is preferably located at the ortho position or meta position with respect to the ion-exchange group. That is, the structural unit A １ preferably contains a 1,4-phenylene group having an ion-exchange group.

[0045] Structural unit A １ The repeating number (x) of the structure within [ ] in the formula (a1) in is preferably 2 to 8, more preferably 3 to 5, from the viewpoint of obtaining better proton conductivity and excellent heat and water resistance.

[0046] Structural unit A １ From the viewpoint of obtaining better proton conductivity, it preferably contains at least one structure selected from the group consisting of the structure represented by the following formula (a1-1) (hereinafter referred to as "structure (a1-1)"), the structure represented by the following formula (a1-2) (hereinafter referred to as "structure (a1-2)"), and the structure represented by the following formula (a1-3) (hereinafter referred to as "structure (a1-3)").

[0047]

[0048]

[0049]

[0050] In formulas (a1-1), (a1-2), and (a1-3), IExG and * have the same meanings as described above. L in formula (a1-3) ３１ represents -O- or -S-. A plurality of IExG may be the same as or different from each other. x in formula (a1-1) １ represents an integer of 2 to 10, and x in formula (a1-2) ２ represents an integer of 2 to 5, and x in formula (a1-3) ３ represents an integer of 1 to 2. However, when the structural unit A １ contains two or more structures selected from the group consisting of structure (a1-1), structure (a1-2), and structure (a1-3), x １ , 2x ２ (the product of 2 and x ２ ) and 4x ３ (the product of 4 and x ３ ) have a total of 6 to 10. x １ is preferably 2 to 5, more preferably 2 to 3, from the viewpoint of obtaining better proton conductivity and excellent heat and water resistance. x ２ is preferably 2 to 3, more preferably 2, from the viewpoint of obtaining better proton conductivity and excellent heat and water resistance. x ３ is preferably 1 from the viewpoint of obtaining better proton conductivity and excellent heat and water resistance.

[0051] The structural unit A １ may consist only of structure (a1-1), or may contain structure (a1-1) and a structure other than structure (a1-1). In the latter case, structure (a1-1) and the structure other than structure (a1-1) may be linked by a linking group (L ３ ). Similarly, the structural unit A １ may consist only of structure (a1-2), or may contain structure (a1-2) and a structure other than structure (a1-2). In the latter case, structure (a1-2) and the structure other than structure (a1-2) may be linked by a linking group (L ３ ). Similarly, the structural unit A １It may consist only of structure (a1-3), or it may include structure (a1-3) and structures other than structure (a1-3). In the latter case, structure (a1-3) and structures other than structure (a1-3) are linking groups (L ３ They may be connected by ).

[0052] Constituent unit A １ This may be a constituent unit represented by any of the following formulas (A1-1) to (A1-4).

[0053]

[0054] IExG and * in formulas (A1-1) to (A1-4), and L in formulas (A1-2) to (A1-4). ３ This is synonymous with the above. Multiple IExG may be the same or different from each other. Multiple L ３ They may be the same or different from one another.

[0055] Constituent unit A １ From the viewpoint of obtaining better proton conductivity and excellent chemical durability, it is preferable that the constituent unit is one of those represented by formulas (A1-1) to (A1-4), and more preferably that it is the constituent unit represented by formula (A1-2). L in formula (A1-2) ３ From the viewpoint of improving proton conductivity and chemical durability, it is preferable that the bond be a single bond.

[0056] Multiple constituent units A in equation (1) １ At least one of them may be one of those exemplified above, and multiple constituent units A １ The majority of these may be those exemplified above, and multiple constituent units A １ All of these may be examples given above.

[0057] Multiple constituent units A in equation (1) １ This is a range where the difference of x in equation (a1) is 3 or less, and there are two or more constituent units A １ It may consist of multiple constituent units A. １ From the viewpoint of obtaining better proton conductivity, the number of types is preferably three or less, and more preferably two or less.

[0058] Multiple constituent units A in equation (1) １ The difference of x in equation (a1) is preferably as close to 0 as possible from the viewpoint of obtaining better proton conductivity, but may be within 2, within 1, or 0.

[0059] [Construction Unit A] ２ ] Component Unit A ２ In this case, the arylene group (Ar) which does not have an ion exchange group is linked to the L group. ４ It has a continuous structure via ).

[0060] The arylene group is a divalent aromatic hydrocarbon group and has a structure obtained by removing two hydrogen atoms from a monocyclic or condensed polycyclic aromatic hydrocarbon. The number of aromatic rings in the arylene group is preferably 1 to 4, more preferably 1 to 2, and even more preferably 1, from the viewpoint of solubility in solvents, film-forming ability, and obtaining better proton conductivity. The arylene group may have substituents other than ion exchange groups. Examples of substituents include alkyl groups and aryl groups. The alkyl group may be at least one group selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups. An example of an aryl group is the phenyl group. When the arylene group has an aryl group as a substituent, the number of aromatic rings in the arylene group includes the number of aromatic rings in the substituent.

[0061] An unsubstituted arylene group may be at least one group selected from the group consisting of phenylene, naphthylene, fluorene, anthracylene, phenanthrylene, triphenylene, pyrenylene, and tetracenylene groups. A substituted arylene group may be at least one group selected from the group consisting of diphenylfluorene, methylphenylene, ethylphenylene, dimethylfluorene, diethylfluorene, dipropylfluorene, diisopropylfluorene, dibutylfluorene, dipentylfluorene, dihexylfluorene, diheptylfluorene, dioctylfluorene, dinonylfluorene, didecylfluorene, diundecylfluorene, and didodecylfluorene groups. Note that a fluorene group as an arylene group means a divalent fluorene group (for example, a fluorene-2,7-diyl group).

[0062] Constituent unit A ２ From the viewpoint of solubility in the solvent, film-forming properties, and obtaining better proton conductivity, it is preferable that the arylene group contains at least one group selected from the group consisting of phenylene, naphthylene, and fluorene groups, which may have substituents, and more preferably contains at least one group selected from the group consisting of phenylene, naphthylene, and fluorene groups, which may have an aryl group as a substituent. Constituent Unit A ２ From the viewpoint of further improving solubility in the solvent and film-forming properties, it is more preferable to contain a phenylene group, and even more preferable to contain a 1,4-phenylene group. From a similar viewpoint, constituent unit A ２ It is particularly preferable that the majority of the multiple arylene groups present in the constituent unit A are of the above preferred embodiment. ２ It is extremely preferable that all of the multiple arylene groups present are independently phenylene groups, naphthylene groups, or fluorene groups, which may each have substituents.

[0063] Constituent unit A ２ From the viewpoint of having excellent solubility in solvents and film-forming properties, as well as excellent mechanical strength of the electrolyte membrane, the linking group (L ４ ) as a single bond, -SO２ Preferably, it contains at least one group selected from the group consisting of - and -CO-, and -SO ２ It is more preferable to include - or -CO-. From a similar viewpoint, constituent unit A ２ Multiple linking groups (L) present inside ４ It is even more preferable that the majority of ) are of the above preferred embodiment, and constituent unit A ２ Multiple linking groups (L) present inside ４ All of the above may be in the preferred form described above.

[0064] Constituent unit A ２ From the perspective of obtaining excellent flexibility, the linking group (L ４ It is preferable that the linking group (L) contains -O- or -S-, and from the viewpoint of excellent chemical durability, ４ ) as a single bond or -SO ２ It is preferable to include -.

[0065] Constituent unit A ２ The linking group inside (L ４ From the viewpoint of excellent solubility in solvents and film-forming properties, as well as excellent mechanical strength of the electrolyte membrane and excellent flexibility, the single bond, -O-, -SO ２ It is preferable that it be - or -CO-.

[0066] Constituent unit A ２ In formula (a2), the number of repeating structures (y) in the brackets [ ] is preferably 4 to 12, and more preferably 5 to 10, from the viewpoint of obtaining better proton conductivity and excellent resistance to hot water.

[0067] Constituent unit A ２ In equation (a2), the number of repeating structures (y) in the brackets [ ] is preferably 2 to 7 more than the number of repeating structures (x) in equation (a1) (x + (2 to 7)), from the viewpoint of achieving both superior proton conductivity and resistance to hot water.

[0068] Constituent unit A ２ The number of aromatic rings in the main chain is preferably 4 to 21, more preferably 5 to 13, and even more preferably 6 to 11, from the viewpoint of obtaining better proton conductivity.

[0069] Constituent unit A ２ From the viewpoint of having excellent solubility in solvents and film-forming properties, as well as excellent mechanical strength of the electrolyte membrane, it is preferable that the material includes at least one structure selected from the group consisting of the structure represented by the following formula (a2-1) and the structure represented by the following formula (a2-2).

[0070]

[0071]

[0072] In formulas (a2-1) and (a2-2), Ar and * have the same meanings as described above. Multiple Ars may be the same or different from one another.

[0073] Constituent unit A including the above structure ２ A concrete example of this is the constituent unit represented by the following formula (A2-1).

[0074]

[0075] Ar, L in equation (A2-1) ４ And * are the same as above, Q indicates the base of the structure represented by formula (a2-1) or formula (a2-2), and y １ and y ２ Each of these independently represents an integer between 2 and 4. １ and y ２ From the viewpoint of obtaining better proton conductivity and excellent resistance to hot water, it is preferably 2 to 3. The multiple Ars may be the same or different from each other, and multiple L ４ They may be the same or different from one another.

[0076] Constituent unit A ２From the viewpoint of obtaining better gas barrier properties, the structure may include at least three consecutive arylene groups linked by single bonds. From the viewpoint of obtaining even better gas barrier properties, the number of consecutive arylene groups via single bonds may be four or more, or five or more. From the viewpoint of obtaining better flexibility, the number of consecutive arylene groups via single bonds may be 10 or less, or 8 or less, or 6 or less. From these viewpoints, the number of consecutive arylene groups via single bonds may be 3 to 10, or 4 to 8 or 5 to 6.

[0077] Constituent unit A including the above structure ２ This may be a constituent unit represented by any of the following formulas (A2-2) to (A2-7).

[0078]

[0079] The * in equations (A2-2) to (A2-7) has the same meaning as above. The R in equations (A2-4) and (A2-6) ３ R represents an alkyl group, and from the viewpoint of obtaining better proton conductivity, its carbon number is preferably 1 to 12 (an integer). ３ Specific examples include methyl, ethyl, propyl, hexyl, and dodecyl groups. In formulas (A2-4) and (A2-6), multiple R ３ They may be the same or different from one another.

[0080] Multiple constituent units A in equation (1) ２ At least one of them may be one of those exemplified above, and multiple constituent units A ２ The majority of these may be those exemplified above, and multiple constituent units A ２ All of these may be examples given above.

[0081] Multiple constituent units A in equation (1) ２ This is a range where the difference of y in equation (a2) is 5 or less, and there are two or more constituent units A ２ It may consist of multiple constituent units A. ２ From the viewpoint of obtaining better gas barrier properties, it is preferable that there be two or more types.

[0082] Multiple constituent units A in equation (1) ２ In equation (a2), the difference of y is preferably as close to 0 as possible from the viewpoint of obtaining better proton conductivity, and may be 4 or less, 3 or less, 2 or less, 1 or less, or 0.

[0083] Multiple constituent units A in equation (1) ２ The difference in the number of aromatic rings in the main chain in formula (a2) is preferable to be close to 0 from the viewpoint of obtaining better proton conductivity, and may be 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, or 0. From a similar viewpoint, the multiple constituent units A in formula (1) ２ The difference in the number of aromatic rings in formula (a2) is preferably as close to 0 as possible, and may be 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, or 0.

[0084] [Connecting group] Polymer (P) is configured with constituent unit A from the viewpoint of obtaining better proton conductivity and superior chemical durability. １ and constituent unit A ２ Linking group between (L １ or L ２ ) as single bonds, -S- and -SO ２ It is preferable to include at least one group selected from the group consisting of -.

[0085] Polymer (P) is a constituent unit A, from the viewpoint of obtaining excellent flexibility. １ and constituent unit A ２ Linking group between (L １ or L ２ It is preferable that the polymer (P) contains -O- or -S- as the constituent unit A. From a similar viewpoint, the constituent unit A which is present in multiple locations in the polymer (P) １ and constituent unit A ２ Linking group between (L １ and L ２ It is more preferable that the majority of these are -O- or -S-, and there are multiple constituent units A in the polymer (P). １ and constituent unit A ２ Linking group between (L １ and L ２ It is even more preferable that all of them are -O- or -S-.

[0086] The polymer (P) may consist of a structure represented by formula (1) and terminal structures bonded to the structure. The polymer (P) may be, for example, a compound represented by any of the following formulas (1-1) to (1-3).

[0087]

[0088] A in equations (1-1) to (1-3) １ A ２ , L １ , L ２ and n are the same as above. However, in equations (1-1) and (1-2), Z ２ L that joins ２ This is a single bond. Z １ and Z ２ Each of these independently represents a hydroxyl group, a thiol group, a halogen atom, a boronic acid group, an alkylborane group, or a boronic acid ester group. Examples of halogen atoms include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). Examples of alkylborane groups include diethylborane, diciamilborane, dicyclohexylborane, and 9-borabicyclo[3.3.1]nonane. Examples of boronic acid ester groups include pinacol boronic acid ester, 1,3-propanediol boronic acid ester, biscyclohexyldiol boronic acid ester, neopentyl glycol boronic acid ester, and catechol boronic acid ester.

[0089] The polymer (P) may contain multiple polymer units (hereinafter also referred to as "polymer unit A") that have the structure represented by formula (1). For example, the polymer (P) may contain three or more polymer units A and three or more crosslinking groups that bond to the polymer units A. A polymer (P) having such crosslinking groups has excellent swelling resistance.

[0090] Polymer unit A is, for example, derived from any of the compounds represented by formulas (1-1) to (1-3) above, from terminal group Z １ and Z ２ It has a structure that excludes the following. Of the two terminal groups of polymer unit A, the terminal group that bonds to the crosslinking group is A １It is fine if A ２ It may also be the case that the terminal group that bonds to the crosslinking group is L ２ In the case of a single bond represented by (i.e., Z in equations (1-1) and (1-2)), ２ L that joins ２ In this case, the terminal group that bonds to the crosslinking group is A ２ It is assumed that the two end groups of polymer unit A may each be bonded to different crosslinking groups. Of the two end groups of polymer unit A, the end group opposite to the end group bonded to the crosslinking group is the end group Z mentioned above. １ and Z ２ It may be bonded to either one of the two. Multiple polymer units A bonded to a single crosslinking group may be the same or different from one another.

[0091] The crosslinking group may be a group derived from a known crosslinkable compound (e.g., decafluorobiphenyl). From the viewpoint of chemical stability, the crosslinking group preferably has one or more aromatic rings. When the crosslinking group has aromatic rings, the polymer units are attached directly to the aromatic rings of the crosslinking group, or to -O-, -S-, or -SO ２ They may be bonded via a cross-linking group. The number of cross-linking groups may be one or more. The multiple cross-linking groups may be the same or different from each other.

[0092] The proportion of the structure represented by formula (1) in the entire polymer (P) is preferably 80% by mass or more, from the viewpoint of obtaining better proton conductivity. From a similar viewpoint, the proportion of the structure represented by formula (1) in the entire polymer (P) may be 85% by mass or more, or 90% by mass or more. The proportion of the structure represented by formula (1) in the entire polymer (P) may be less than 100% by mass. The proportion of the structure represented by formula (1) in the entire polymer (P) may be 80% by mass or more and less than 100% by mass, 85% by mass or more and less than 100% by mass, or 90% by mass or more and less than 100% by mass.

[0093] The polymer (P) may contain fluorine atoms, but the fluorine content in the polymer (P) is preferably 5% by mass or less, and it is preferable that the polymer (P) does not contain fluorine atoms (the fluorine content is below the detection limit).

[0094] The number-average molecular weight of the polymer (P) may be 20,000 or more, 25,000 or more, or 30,000 or more from the viewpoint of superior proton conductivity and superior mechanical strength of the electrolyte membrane, and may be 300,000 or less, 200,000 or less, or 150,000 or less from the viewpoint of superior solubility in the solvent and film formation. From these viewpoints, the number-average molecular weight of the polymer (P) may be 20,000 to 300,000, 25,000 to 200,000, or 30,000 to 150,000.

[0095] The weight-average molecular weight of polymer (P) may be 40,000 or more, 50,000 or more, or 60,000 or more from the viewpoint of superior proton conductivity and superior mechanical strength of the electrolyte membrane, and may be 500,000 or less, 300,000 or less, 200,000 or less, 80,000 or less, 70,000 or less, or 60,000 or less from the viewpoint of superior solubility in solvents and film formation. From these viewpoints, the weight-average molecular weight of polymer (P) may be 40,000 to 500,000, 50,000 to 300,000, 60,000 to 200,000, 40,000 to 80,000, 40,000 to 70,000, 40,000 to 60,000, 50,000 to 80,000, or 60,000 to 80,000.

[0096] The ratio of the weight-average molecular weight to the number-average molecular weight of the polymer (P) (polydispersity) may be 1.5 or higher, and may be 2.0 or higher, 2.5 or higher, or 2.8 or higher. When the polydispersity of the polymer (P) is 2.5 or higher, excellent swelling resistance tends to be obtained. From the viewpoint of solubility in the solvent, the polydispersity of the polymer (P) may be 20.0 or lower, and may be 15.0 or lower, 10.0 or lower, 5.0 or lower, 3.0 or lower, or 2.5 or lower. From these viewpoints, the polydispersity of the polymer (P) may be 1.5 to 20.0, 2.0 to 20.0, 2.5 to 20.0, 2.5 to 15.0, 2.8 to 10.0, 1.5 to 5.0, 1.5 to 3.0, or 1.5 to 2.5.

[0097] The number-average molecular weight and weight-average molecular weight of polymer (P) are measured by gel permeation chromatography (GPC) and are expressed as standard polyethylene glycol / oxide (PEG / PEO) equivalent values.

[0098] Polymer (P) uses tetramethylsilane as an internal standard. １ In the 1H-NMR spectrum, a peak may be present in the range of 6.70 to 6.95 ppm. If the peak is split into a doublet or other multiplet, the median value of the peak is taken as the chemical shift value of that peak. Polymers (P) that have such a peak tend to have excellent chemical durability. The above peak may originate from the ortho hydrogen atom of the hydroxyl group in the aromatic ring at the end of polymer (P). １ The 1H-NMR spectrum can be measured by the method described in the examples below.

[0099] The ion exchange capacity (IEC) of the polymer (P) may be 1.0 mmol / g or more, 1.5 mmol / g or more, 1.8 mmol / g or more, 2.0 mmol / g or more, or 2.4 mmol / g or more from the viewpoint of superior proton conductivity, and may be 3.5 mmol / g or less, 3.0 mmol / g or less, or 2.8 mmol / g or less from the viewpoint of superior swelling resistance. From these viewpoints, the ion exchange capacity of the polymer (P) may be 1.0 to 3.5 mmol / g, 1.5 to 3.0 mmol / g, 1.8 to 2.8 mmol / g, 2.0 to 2.8 mmol / g, or 2.4 to 2.8 mmol / g.

[0100] The ion exchange capacity of polymer (P) is measured by the following procedure (1) to (7): (1) Dissolve polymer (P) in dimethyl sulfoxide (DMSO) to obtain a solution containing 15% by mass of polymer (P). (2) Cast the obtained solution onto a glass substrate and dry it at 60°C for 12 hours to produce a film. (3) Immerse the obtained film in 1 M hydrochloric acid for 24 hours, then wash it by immersing it in pure water. (4) Dry the electrolyte film after washing and determine the dry mass. Drying is carried out until the mass loss when the electrolyte film is heated at 80°C is 1% by mass / hour or less. For example, after drying under reduced pressure, heat it at 80°C for 12 hours or more. (5) Immerse the dried film in a 20% by mass aqueous sodium chloride solution and stir for 24 hours to perform ion exchange. (6) Using the point where the pH becomes 7 as the endpoint, titrate the hydrochloric acid produced by the above ion exchange using a 0.01 M aqueous sodium hydroxide solution. (7) The ion exchange capacity (IEC) of the polymer (P) is calculated using the following formula: IEC (unit: mmol / g) = {concentration of sodium hydroxide aqueous solution (unit: mol / L) × drop volume (unit: mL)} / dry mass of electrolyte membrane (unit: g)

[0101] Polymer (P) can be obtained, for example, by reacting (polymerizing) a compound represented by the following formula (b1) (hereinafter also referred to as "compound (b1)") with a compound represented by the following formula (b2) (hereinafter also referred to as "compound (b2)"). That is, polymer (P) may be a polymer of compound (b1) and compound (b2). However, at least one of compound (b1) and compound (b2) is a plurality of A in the above formula (1). １ The difference of x in the above formula (a1) is 3 or less, and multiple A in the above formula (1) ２ In the above equation (a2), the difference of y is within 5, １ Or A ２ It contains two or more compounds of different types.

[0102]

[0103] In formula (b1), A １ This is synonymous with the above, X １ｂ and X ２ｂEach of these independently represents a halogen atom. Examples of halogen atoms include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0104]

[0105] In formula (b2), A ２ This is synonymous with the above, Z １ｂ and Z ２ｂ Each of these independently represents a hydroxyl group, a thiol group, a halogen atom, a boronic acid group, an alkylborane group, or a boronic acid ester group. Examples of halogen atoms, alkylborane groups, and boronic acid ester groups are given above, Z １ and Z ２ These are the same examples as halogen atoms, alkylborane groups, and boronic acid ester groups represented by .

[0106] In the above method, constituent unit A １ and constituent unit A ２ A structure in which these are arranged alternately (a repeating structure) can be formed throughout the polymer. Therefore, according to the above method, the number of repeats n in formula (1) can be easily set to 10 or more.

[0107] According to the above method, L in equation (1) １ and L ２ A polymer (P) is obtained in which the bonds are -O-, -S-, or single bonds. Specifically, Z １ｂ and Z ２ｂ If at least one of them is a hydroxyl group, then L in formula (1) １ and L ２ A polymer (P) is obtained in which at least one of the elements is -O-, Z １ｂ and Z ２ｂ If at least one of them is a thiol group, then L in formula (1) １ and L ２ A polymer (P) is obtained in which at least one of the elements is -S-, Z １ｂ and Z ２ｂ If at least one of them is a halogen atom, a boronic acid group, an alkylborane group, or a boronic acid ester group, then L in formula (1) １ and L ２A polymer (P) is obtained in which at least one of the bonds is a single bond.

[0108] In the above method, A is calculated within the range where the difference of x in equation (a1) is 3 or less. １ The method involves using multiple types of compounds (b1) with different structures, and ensuring that the difference in y in formula (a2) is within 5. ２ It is permissible to use multiple types of compounds (b2) with different structures. As for compound (b1), X １ｂ and / or X ２ｂ It is also possible to use multiple types of compounds with different properties. Similarly, as compound (b2), Z １ｂ and / or Z ２ｂ It is also possible to use multiple types of compounds with different properties.

[0109] Compound (b1) and compound (b2) can be reacted (polymerized) by, for example, an aromatic nucleophilic substitution reaction in a solvent in the presence of a base.

[0110] The solvent used in the reaction is preferably one that is a good solvent for compound (b1), compound (b2), and polymer (P), and that allows for the high molecular weight of polymer (P) during polymerization. For example, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, diphenyl sulfone, sulfolane, 1,3-dimethyl-2-imidazolidinone, and tetramethylurea are preferably used. These solvents may be used individually or as a mixture of two or more.

[0111] A base is used to enhance the nucleophilicity of compound (b2). The base is not particularly limited as long as it can deprotonate compound (b2). For example, alkali metal hydroxides and carbonates, alkaline earth metal hydroxides and carbonates, and organic bases such as amines can be used. The alkali metal may be lithium, sodium, potassium, rubidium, or cesium. The alkaline earth metal may be magnesium, calcium, strontium, or barium.

[0112] The reaction temperature in aromatic nucleophilic substitution reactions may be in the range of 25 to 350°C. From the viewpoint of excellent reaction rate, the reaction temperature is preferably 60°C or higher, and more preferably 100°C or higher. From the viewpoint of suppressing polymer decomposition, the reaction temperature is preferably 300°C or lower, and more preferably 250°C or lower. From these viewpoints, the reaction temperature is preferably 60 to 300°C, and more preferably 100 to 250°C.

[0113] Compound (b1) and compound (b2) can also be reacted (polymerized) by a cross-coupling reaction in a solvent in the presence of a catalyst. Examples of solvents that can be used in the reaction are the same as examples of solvents that can be used in the aromatic nucleophilic substitution reaction described above.

[0114] There are no particular restrictions on the catalyst as long as it can carry out the cross-coupling reaction, and conventionally known catalysts can be used. For coupling reactions between halogens, for example, copper catalysts, nickel catalysts, or palladium catalysts can be used. For coupling reactions between halogens and boronic acid groups, alkylborane groups, or boronic acid ester groups, for example, conventionally known catalysts used in the Suzuki-Miyaura coupling reaction (palladium catalysts, nickel catalysts, etc.) can be used.

[0115] The copper catalyst may be, for example, copper(I) 2-thiophenecarboxylate or tetrakis(acetonitrile)copper(I)hexafluorophosphate.

[0116] The nickel catalyst may be, for example, bis(1,5-cyclooctadiene)nickel(0), dibromobis(triphenylphosphine)nickel(II), or [1,1'-bis(diphenylphosphino)ferrocene]dichloronickel(II).

[0117] The palladium catalyst may be, for example, tetrakis(triphenylphosphine)palladium(0), palladium(II) acetate, bis(triphenylphosphine)palladium(II) dichloride, or [1,1'-bis(diphenylphosphine)ferrocene]dichloropalladium(II).

[0118] The reaction temperature in the cross-coupling reaction may be in the range of 0 to 350°C. From the viewpoint of improving the reaction rate, the reaction temperature is preferably 30°C or higher, and more preferably 60°C or higher. From the viewpoint of suppressing polymer decomposition, the reaction temperature is preferably 300°C or lower, and more preferably 250°C or lower. From these viewpoints, the reaction temperature is preferably 30 to 300°C, and more preferably 60 to 250°C.

[0119] In the aromatic nucleophilic substitution and cross-coupling reactions described above, it is preferable to remove water from the reaction system in order to increase the molecular weight of the polymer (P). The method of dehydration is not particularly limited, but examples include azeotropic dehydration by coexisting an azeotropic solvent in the reaction system, continuous removal from the reaction system by heating above the boiling point of water, and coexisting a water-absorbing agent such as a molecular sieve. The azeotropic solvent is not particularly limited as long as it can remove water, and for example, at least one selected from the group consisting of benzene, toluene, cyclohexane, and xylene may be used.

[0120] The above aromatic nucleophilic substitution and cross-coupling reactions are preferably carried out under an inert atmosphere (for example, under a nitrogen or argon atmosphere). After the polymerization reaction is complete, the polymer can be recovered from the reaction solution and purified to obtain the desired polymer. Methods for recovering the polymer from the reaction solution include, for example, adding the reaction solution to a solvent in which the polymer has low solubility, allowing the polymer to precipitate and be recovered as a solid, and removing the solvent from the reaction solution by evaporation and recovering the polymer as a solid. Methods for purifying the polymer include, for example, washing in a solvent in which the polymer has low solubility and the by-product inorganic salts and residual monomer-derived compounds have high solubility, and washing using a Soxhlet extractor. The methods for recovering and purifying the polymer are not limited to these methods.

[0121] Polymer (P) can also be obtained by oxidizing a polymer having the structure represented by formula (1) (for example, a polymer of compound (b1) and compound (b2)). More specifically, polymer (P) is obtained from among polymers having the structure represented by formula (1), L１ , L ２ , L ３ or L ４ It can be an oxide of a polymer containing a -S- (sulfide group) (hereinafter referred to as "sulfide-containing polymer").

[0122] Polymer (P) can also be obtained by reacting (polymerizing) a polymer of compound (b1) and compound (b2) or an oxide thereof with a compound having three or more groups that react with the polymer or oxide to form a crosslink (hereinafter also referred to as "crosslinkable compound (d)"). That is, polymer (P) may be a reaction product of a polymer of compound (b1) and compound (b2) or an oxide thereof with a crosslinkable compound (d). However, at least one of compound (b1) and compound (b2) is a plurality of A in formula (1) above. １ The difference of x in the above formula (a1) is 3 or less, and multiple A in the above formula (1) ２ In the above equation (a2), the difference of y is within 5, １ Or A ２ This method contains two or more compounds of different types. This method can yield a polymer (P) having a polymer of compound (b1) and compound (b2) or an oxide thereof as polymer units.

[0123] The crosslinkable compound (d) may be a known crosslinkable compound, and from the viewpoint of chemical stability, it is preferable that it has one or more aromatic rings. The crosslinkable compound (d) may be, for example, decafluorobiphenyl.

[0124] The polymer (P) may be obtained by a method that includes a step of protonating the ion exchange groups that form salts with metal ions. This step may involve immersing the polymer obtained by the method described above (for example, a polymer of compound (b1) and compound (b2) or an oxide thereof, or a reaction product of the polymer or oxide and a crosslinkable compound (d)) in an acid (for example, hydrochloric acid) to protonate the ion exchange groups (for example, a salt of a sulfonic acid group). By washing and drying the compound (for example, a powder) after immersion, the metal ions of the polymer before immersion are replaced with protons, and a polymer (P) in which the ion exchange groups are protonated is obtained.

[0125] <Electrolyte Material and Electrolyte Membrane> The electrolyte material of one embodiment is a material containing an electrolyte, and contains the above polymer (P) as the electrolyte. The electrolyte membrane of one embodiment is a membrane containing an electrolyte, and contains the above polymer (P) as the electrolyte. The electrolyte material is used to form the electrolyte membrane. That is, the electrolyte membrane may be made of the electrolyte material.

[0126] The electrolyte material and electrolyte membrane have excellent proton conductivity because they contain polymer (P). The proton conductivity of the electrolyte membrane is, for example, 130 mS / cm or higher, and may be 150 mS / cm or higher or 180 mS / cm or higher, in an environment of 80°C and 100% relative humidity.

[0127] Electrolyte materials and electrolyte membranes also tend to exhibit excellent gas barrier properties. The gas barrier properties of an electrolyte membrane can be confirmed by the hydrogen gas permeability measured by a hydrogen gas permeability test. For example, the hydrogen gas permeability of an electrolyte membrane is 1.00 × 10⁻¹⁶ under conditions of 80°C and 60% relative humidity. －７ cm ３ mm / (cm) ２ It is less than or equal to s kPa, and 0.50 × 10 －７ cm ３ mm / (cm) ２ (s・kPa) or less or 0.30 × 10 －７ cm ３ mm / (cm) ２ It may be less than or equal to s・kPa.

[0128] Electrolyte materials and electrolyte membranes may also have a microphase separation structure when immersed in water (wet state). Specifically, when small-angle X-ray scattering (SAXS) measurements are performed on an electrolyte membrane immersed in water, the resulting peak interplanar spacing (interplanar spacing d) may be 4.0 nm or greater.

[0129] Electrolyte materials and electrolyte membranes may also have a microphase separation structure in a vacuum-dried state (dry state). Specifically, when small-angle X-ray scattering (SAXS) measurements are performed on an electrolyte membrane in a vacuum-dried state, the resulting peak interplanar spacing (interplanar spacing d) may be 2.5 nm or greater.

[0130] The electrolyte material and electrolyte membrane may consist solely of polymer (P), or they may contain components other than polymer (P). That is, the electrolyte material may be a composition. Components other than polymer (P) may be additives such as water-retaining inorganic substances or radical scavengers. Specific examples of additives include water, silica, cerium oxide, and manganese oxide. These components may be used individually or in combination.

[0131] The polymer (P) content in the electrolyte material and electrolyte membrane may be 80 to 100% by mass, 90 to 100% by mass, or 95 to 100% by mass. The above content is based on the total amount of solids in the electrolyte material or electrolyte membrane.

[0132] The thickness of the electrolyte membrane is not particularly limited and can be changed according to the size of the fuel cell, etc. From the viewpoint of increasing the mechanical strength of the membrane while reducing membrane resistance, the thickness of the electrolyte membrane may be, for example, 1 to 200 μm, or it may be 1 to 100 μm or 1 to 50 μm.

[0133] There are no particular limitations on the method for manufacturing the electrolyte membrane, and it can be manufactured by known methods for forming an electrolyte polymer film. Examples of methods for manufacturing the electrolyte membrane include the solution casting method, the dispersion casting method, the melt press method, and the melt extrusion method.

[0134] In the solution casting method, for example, an electrolyte film can be obtained by using a solution containing a polymer (P) as the electrolyte material, casting the solution onto a substrate, removing the solvent, and then peeling the film off the substrate.

[0135] The solvent used in the solution casting method is not particularly limited as long as it is capable of dissolving the polymer (P). For example, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, diphenyl sulfone, sulfolane, 1,3-dimethyl-2-imidazolidinone, and tetramethylurea can be used. These may be used individually or in combination.

[0136] In the dispersion casting method, for example, an electrolyte film can be obtained by using a dispersion containing a polymer (P) as the electrolyte material, casting the dispersion onto a substrate, removing the dispersion medium, and then peeling the film off the substrate.

[0137] The dispersion medium used in the dispersion casting method is not particularly limited as long as it is a dispersion medium capable of dispersing the polymer (P). For example, water, ethers, alcohols, ketones, esters, carboxylic acids, amines, acetonitrile, nitromethane, toluene, xylene, chlorobenzene, and chloroform can be used. Examples of ethers include tetrahydrofuran and diethyl ether. Examples of alcohols include methanol, ethanol, 1-propanol, isopropyl alcohol, and 1-butanol. Examples of ketones include acetone and cyclohexanone. Examples of esters include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, methyl lactate, and ethyl lactate. Examples of carboxylic acids include formic acid, acetic acid, and propionic acid. Examples of amines include dimethylamine, diethylamine, triethylamine, pyridine, triethanolamine, and piperazine. These may be used individually or in combination.

[0138] A method for manufacturing an electrolyte membrane according to one embodiment may further include a step of washing the obtained membrane (hereinafter referred to as the "washing step"). In the washing step, the membrane may be washed using a washing solution. In this case, the electrolyte membrane is obtained by drying the membrane after the washing step by a method such as vacuum drying. As the washing solution, a known washing solution according to the purpose of washing may be used. Specific examples of washing solutions include hydrogen peroxide, sulfuric acid, hydrochloric acid, nitric acid, and pure water. These may be used individually or in combination of two or more.

[0139] The electrolyte material and electrolyte membrane are suitably used in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers. The electrolyte material and electrolyte membrane can also be used in redox flow batteries, electrochemical hydrogen pumps, chlor-alkali electrolyzers, solid acid catalysts, membrane-type humidity control devices, gas separation membranes, and the like.

[0140] The electrolyte membrane can also be used in combination with a microporous membrane, nonwoven fabric, mesh, etc. That is, another embodiment of the present disclosure is a laminate comprising an electrolyte membrane and another membrane (microporous membrane, nonwoven fabric, mesh, etc.).

[0141] <Electrolyte membrane with catalyst layer> An electrolyte membrane with a catalyst layer according to one embodiment comprises the electrolyte membrane of the above embodiment and a catalyst layer disposed on one or both sides of the electrolyte membrane.

[0142] The catalyst layer is, for example, a layer composed of an anode catalyst or a cathode catalyst, such as in a polymer electrolyte fuel cell or polymer electrolyte water electrolysis device. Hereinafter, a layer composed of an anode catalyst will be referred to as the anode catalyst layer, and a layer composed of a cathode catalyst will be referred to as the cathode catalyst layer.

[0143] The composition of the catalyst layer is not particularly limited and can be a conventionally known configuration for catalyst layers (anode catalyst layer, cathode catalyst layer) in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers. The catalyst layer may be formed of a conductive composition containing, for example, an anode catalyst or cathode catalyst and a conductive material. The catalyst layer may also contain an ionomer.

[0144] As an anode catalyst in a polymer electrolyte fuel cell, a metal catalyst capable of promoting the oxidation reaction of fuels such as hydrogen can be used. As an anode catalyst in a polymer electrolyte water electrolysis device, a metal catalyst capable of promoting the oxygen evolution reaction can be used. For example, platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium, tungsten, manganese, and vanadium, as well as alloys of two or more of these, can be used. These may be used individually or in mixtures of two or more.

[0145] As a cathode catalyst in a polymer electrolyte fuel cell, a metal catalyst capable of promoting the reduction reaction of oxygen can be used, and as a cathode catalyst in a polymer electrolyte water electrolysis device, a metal catalyst capable of promoting the hydrogen evolution reaction can be used. For example, platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium, tungsten, manganese, and vanadium, as well as alloys of two or more of these, can be used. These may be used individually or in mixtures of two or more.

[0146] Examples of conductive materials that can be used include carbon blacks such as furnace black, Ketjen black, channel black, and acetylene black, activated carbon, and graphite. These may be used individually or in combination of two or more.

[0147] Conventional known materials can be used as the ionomer; for example, an ionomer containing a perfluoro electrolyte can be used. Alternatively, the above-mentioned polymer (P) can be used as the ionomer. It is preferable to use a material with high oxygen permeability as the ionomer. There are no particular restrictions on the amount of ionomer added to the catalyst layer, but it is preferable to adjust the amount added within a range where oxygen diffusion is not easily inhibited.

[0148] The catalyst layer may further contain additives such as water repellents like fluorinated carbon, binders like fluororesins and hydrocarbon resins having sulfonic acid groups.

[0149] A laminate comprising an electrolyte membrane with an anode catalyst layer and a cathode catalyst layer on both sides (for example, a laminate with a layer configuration of "anode catalyst layer / electrolyte membrane / cathode catalyst layer") is also called a CCM (Catalist Coated Membrane) and is suitably used in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers.

[0150] In the above embodiment, instead of the electrolyte membrane, a laminate comprising an electrolyte membrane and the other membranes mentioned above (microporous membrane, nonwoven fabric, mesh, etc.) can also be used.

[0151] <Membrane electrode assembly> A membrane electrode assembly according to one embodiment comprises the electrolyte membrane of the above embodiment and an electrode layer disposed on one or both sides of the electrolyte membrane.

[0152] The electrode layer comprises, for example, the catalyst layer (anode catalyst layer or cathode catalyst layer) in the electrolyte membrane with catalyst layer of the above embodiment. Hereinafter, an electrode layer comprising an anode catalyst layer will be referred to as the anode layer, and an electrode layer comprising a cathode catalyst layer will be referred to as the cathode layer.

[0153] The configuration of the electrode layer is not particularly limited and may be a configuration conventionally known as the electrode layer (anode layer, cathode layer) of a polymer electrolyte fuel cell or polymer electrolyte water electrolysis device. The electrode layer may consist, for example, of the catalyst layer (anode catalyst layer or cathode catalyst layer) and a gas diffusion substrate. If the catalyst layer itself has gas diffusivity, the electrode layer may consist only of the catalyst layer. As the gas diffusion substrate, for example, a porous membrane can be used. As the gas diffusion substrate, in addition to gas diffusivity, materials that have water repellency and conductivity can also be used (for example, carbon fiber substrates such as carbon nonwoven fabric or carbon paper, or titanium fiber sintered bodies).

[0154] A laminate comprising an electrolyte membrane with an anode layer and a cathode layer as electrode layers on both sides (for example, a laminate with a layer configuration of "gas diffusion substrate / anode catalyst layer / electrolyte membrane / cathode catalyst layer / gas diffusion substrate") is also called a MEA (Membrane Electrode Assembly) and is suitably used in polymer electrolyte fuel cells and polymer electrolyte water electrolyzers.

[0155] In the above embodiment, instead of the electrolyte membrane, a laminate comprising an electrolyte membrane and the other membranes mentioned above (microporous membrane, nonwoven fabric, mesh, etc.) can also be used.

[0156] <Solid Polymer Fuel Cell> A solid polymer fuel cell according to one embodiment comprises the membrane electrode assembly of the above embodiment.

[0157] The configuration of a polymer electrolyte fuel cell is not particularly limited and may be a conventionally known configuration, except that the membrane electrode assembly of the above embodiment is used. A polymer electrolyte fuel cell may, for example, comprise two or more membrane electrode assemblies. The two or more membrane electrode assemblies may be stacked (laminated) with a separator in between. A separator conventionally known for polymer electrolyte fuel cells can be used as the separator.

[0158] <Solid Polymer Water Electrolyzer> A solid polymer water electrolyzer according to one embodiment includes the membrane electrode assembly according to the above embodiment.

[0159] The configuration of the polymer electrolyte water electrolysis apparatus is not particularly limited, and can be a conventionally known configuration except for the use of the membrane electrode assembly of the above embodiment. The polymer electrolyte water electrolysis apparatus may, for example, further include a power supply element outside the membrane electrode assembly. It may also include two or more membrane electrode assemblies.

[0160] The contents of this disclosure will be described in more detail below using examples and comparative examples, but this disclosure is not limited to the following examples.

[0161] <Synthesis Example 1> (Synthesis of hydrophilic monomer (M1)) A 10 L flask equipped with a dropping funnel, reflux condenser, and mechanical stirrer was purged with nitrogen, and 101 g of 4,4'-bis[(4-chlorophenyl)sulfonyl]-1,1'-biphenyl and 4 L of anhydrous tetrahydrofuran were charged in, and stirring was started. The mixture was cooled to -70°C in a methanol-dry ice bath, and 320 mL of 2.6 mol / L n-butyllithium-hexane solution was added dropwise. The mixture was stirred for 1 hour while remaining cooled in the bath. 40 mL of sulfur dioxide gas was introduced into the flask with nitrogen gas. The mixture was stirred for 30 minutes while remaining cooled in the bath. After that, the bath was removed and the internal temperature was raised to 0°C. The precipitated solid was filtered off by suction filtration and washed with 200 mL of tetrahydrofuran. The recovered solid was dissolved in 2 L of pure water, 260 mL of 35% hydrogen peroxide solution was added, and the mixture was stirred for 18 hours. The solid was removed by suction filtration, and 600 g of sodium chloride was added to the recovered filtrate. The precipitated white solid was recovered by suction filtration and purified by recrystallization from water / isopropyl alcohol. The obtained solid was dried under reduced pressure to obtain a hydrophilic monomer (M1) represented by the following formula (M1). The yield was 65%.

[0162]

[0163] <Synthesis Example 2> (Synthesis of hydrophobic monomer (M2)) In a 200 mL flask equipped with a stirring bar, Dean-Stark tube, reflux condenser, and calcium chloride tube, 4.0 g of 4,4'-bis[(4-chlorophenyl)sulfonyl]-1,1'-biphenyl, 14.8 g of [1,1'-biphenyl]-4,4'-diol, and 13.2 g of potassium carbonate were charged, and 50 mL of N,N-dimethylacetamide (DMAc) and 50 mL of toluene were added. The mixture was heated to 160°C in an oil bath while stirring, and heating and stirring were continued for 4 hours. The toluene was removed from the Dean-Stark tube, and the mixture was heated to 180°C in an oil bath. After heating, heating and stirring were continued for 8 hours. After the reaction mixture was allowed to cool to room temperature (approximately 25°C), the reaction mixture was poured into 200 mL of 10% hydrochloric acid, and the precipitated white solid was filtered off. The filtered solid was washed with 300 mL of ethanol and dried. The dried solid was purified by recrystallization from N-methylpyrrolidone (NMP) / ethanol. The resulting solid was dried under reduced pressure to obtain a hydrophobic monomer (M2) represented by the following formula (M2). The yield was 50%.

[0164]

[0165] <Synthesis Example 3> (Synthesis of hydrophobic monomer (M3)) A 500 mL flask equipped with a stirring bar and condenser was purged with nitrogen. To this flask, 9.5 g of 2,7-dibromo-9,9-diphenylfluorene, 12.1 g of 4'-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)biphenyl-4-ol, 19 g of potassium carbonate, 2.0 g of tetrakis(triphenylphosphine)palladium(0), and 250 mL of tetrahydrofuran were added. The reaction mixture was heated to 90°C and stirred for 3 hours. After the reaction mixture was allowed to cool to room temperature, 200 mL of water and 500 mL of ethyl acetate were added and the mixture was separated, and the organic layer was recovered. The solvent was removed by evaporation using an evaporator, and the resulting crude product was purified by silica column chromatography using an ethyl acetate / hexane = 1 / 1 (volume ratio) mixed solvent as the developing solvent. The fraction containing the target product was recovered, and the solvent was removed by evaporation using an evaporator. The obtained solid was dried under reduced pressure to obtain a hydrophobic monomer (M3) represented by the following formula (M3). The yield was 53%.

[0166]

[0167] <Synthesis Example 4> (Synthesis of hydrophobic monomer (M4)) A 500 mL flask equipped with a stirring bar and a condenser was purged with nitrogen. 20 g of anhydrous aluminum chloride, 10 g of isophthaloyl chloride, and 240 mL of 1,2-dichlorobenzene were added to this flask. While stirring the reaction mixture, 24 g of 3-bromo-1,1'-biphenyl was added dropwise. The reaction mixture was heated to 40°C and stirred for 3 hours. After the reaction mixture cooled to room temperature, it was added to 900 mL of ice-cold 3% hydrochloric acid, and stirred at room temperature for 18 hours. The precipitated white solid was collected by suction filtration and washed with ethanol. The obtained solid was dried under reduced pressure and used in the next reaction.

[0168] 0.80 g of the obtained dried solid, 0.71 g of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenol, 0.11 g of [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride dichloromethane adduct, and 0.57 g of sodium carbonate were added to a 100 mL flask and the flask was purged with nitrogen. 30 mL of tetrahydrofuran (THF) was added, and the reaction mixture was heated to 50°C while vigorously stirring. Heating and stirring were continued at 50°C for 22 hours. After the reaction mixture had cooled, 100 mL of chloroform and 100 mL of 5% hydrochloric acid were added and separated, and the organic layer was recovered. The solvent was removed using an evaporator, and 20 mL of ethyl acetate was added to suspend the mixture. The suspension was filtered by suction, the filtrate was collected, and the solvent was removed using an evaporator to obtain an orange oily substance. The resulting oily substance was dissolved in ethyl acetate and purified by silica column chromatography using a 1 / 1 (volume ratio) ethyl acetate / hexane mixed solvent as the developing solvent. The fraction containing the target substance was recovered, and the solvent was removed by evaporation. The resulting solid was purified by recrystallization from hot toluene. The resulting solid was dried under reduced pressure to obtain a hydrophobic monomer (M4) represented by the following formula (M4). The yield was 60%.

[0169]

[0170] <Synthesis Example 5> (Synthesis of hydrophobic monomer (M5)) A 500 mL flask equipped with a stirring bar and condenser was purged with nitrogen. 41 g of 4,4'-thiobisbenzenethiol, 14 g of 4,4'-bis[(4-chlorophenyl)sulfonyl]-1,1'-biphenyl, 80 mL of DMAc, and 4 g of potassium carbonate were added to the flask. The mixture was heated to 100°C in an oil bath while stirring, and heating and stirring were continued for 6 hours. After the reaction mixture cooled to room temperature, 100 mL of 1 M hydrochloric acid was added, and the precipitated solid was collected by suction filtration. The collected solid was dissolved in dichloromethane and purified by silica column chromatography using dichloromethane as the developing solvent. The fraction containing the target product was collected, and the solvent was removed by evaporation using an evaporator. The obtained solid was purified by recrystallization from dichloromethane. The obtained solid was dried under reduced pressure to obtain the hydrophobic monomer (M5) represented by the following formula (M5). The yield was 40%.

[0171]

[0172] <Structures represented by formulas (P1) to (P4)> Table 1 shows the structures represented by formulas (P1) to (P4) of polymers (P1) to (P5) in Examples 1 to 4 and Comparative Example 1 described below. In formulas (P1) to (P4) below, M represents Na, K, or H, and x, y, and n represent positive numbers. The synthesis methods for polymers (P1) to (P5) are as described in Examples 1 to 4 and Comparative Example 1 described below.

[0173]

[0174] <Example 1> (Synthesis of polymer (P1)) 1.476 g of hydrophobic monomer (M2) obtained in Synthesis Example 2, 1.278 g of hydrophobic monomer (M3) obtained in Synthesis Example 3, 3.545 g of hydrophilic monomer (M1) obtained in Synthesis Example 1, and 1.956 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 30 mL of dimethyl sulfoxide (DMSO) and 30 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out by heating to 150 °C for 118 hours. After the reaction mixture was allowed to cool to room temperature, it was reprecipitated and purified from 1 L of isopropyl alcohol (IPA), and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P1) having the structure represented by the above formula (P1). The yield was 90%. In equation (P1) above, x was approximately 0.55 (0.51 to 0.59), y was approximately 0.45 (0.41 to 0.49), and n was approximately 15. Note that n in equation (P1) was calculated from the number-average molecular weight described later. The same applies to n in equations (P2) to (P4) described later.

[0175] (Molecular Weight Measurement) The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of polymer (P1) were measured under the following conditions, and the polydispersity (Mw / Mn) was determined. Mn was 20,000, Mw was 46,000, and Mw / Mn was 2.3.

[0176] [Measurement Conditions] Polymer (P1) was dissolved at a concentration of 1 mg / mL in an eluent (N,N-dimethylformamide solvent containing 10 mmol / L of lithium bromide) to prepare the sample solution. A Tosoh HLC-8320GPC was used as the apparatus. Two Tosoh TSKgel SuperAWM-H columns (6.0 mm inner diameter, 15 cm length) were used. A differential refractometer was used as the detector. The flow rate was 0.6 mL / min and the temperature was 40°C. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) were determined by converting to standard polyethylene glycol / oxide (PEG / PEO). Furthermore, the polydispersity (Mw / Mn) was determined by dividing the weight-average molecular weight (Mw) by the number-average molecular weight (Mn).

[0177] ( １ (H-NMR measurement) Under the following conditions, the polymer (P1) １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.83–6.87 ppm.

[0178] [Measurement Conditions] For 1H-NMR measurements, an AVANCE III HD 400 (400MHz, manufactured by Bruker) was used as the apparatus. １ ¹H-NMR was performed using heavy DMSO as the measurement solvent and tetramethylsilane (TMS) as the internal standard. Commercially available reagents were used.

[0179] (Preparation of electrolyte membrane) The obtained polymer (P1) was dissolved in DMSO to obtain a solution containing 15% by mass of polymer (P1). The obtained solution was cast onto a glass substrate and dried at 60°C for 12 hours to obtain a film (film thickness 33 μm). The obtained film was immersed in 1 M hydrochloric acid for 24 hours to remove metal ions (Na ＋ or K ＋ ) to proton (H ＋ After substitution with (), the material was thoroughly washed by immersion in pure water and dried under reduced pressure to obtain the electrolyte membrane of Example 1 (an electrolyte membrane consisting of a proton-substituted polymer (P1), with a film thickness of 33 μm). The "film thickness" in this example was measured using PG-02 manufactured by TECLOK CORPORATION. The same applies to the "film thickness" in the following examples and comparative examples.

[0180] (Ion Exchange Capacity Measurement) The electrolyte membrane from Example 1 was dried at 80°C for 12 hours or more, and its dry mass was determined. The dried electrolyte membrane was immersed in a 20% sodium chloride aqueous solution and stirred for 24 hours to perform ion exchange. The resulting hydrochloric acid was titrated using a 0.01 M sodium hydroxide aqueous solution. An automatic titrator COM-A19 manufactured by HIRANUMA Corporation was used for the titration, and the endpoint was set at a pH of 7. The ion exchange capacity (IEC) was calculated using the following formula. The IEC of the electrolyte membrane from Example 1 was 2.4 mmol / g. IEC (unit: mmol / g) = {Concentration of sodium hydroxide aqueous solution (unit: mol / L) × Droplet volume (unit: mL)} / Dry mass of electrolyte membrane (unit: g)

[0181] (Evaluation) [Proton Conductivity Evaluation] The proton conductivity of the obtained electrolyte membrane was measured by the following method. Using a Teflon® measurement cell (Scribner, BT-115), the fabricated electrolyte membrane was placed in the cell in contact with four platinum wires. After being held at 80°C and 20% relative humidity for 2 hours, the relative humidity was increased by 10% and held for 30 minutes. This operation was continued until the relative humidity reached 100%, and then DC resistance measurement was performed using the four-terminal method at 100% relative humidity. The proton conductivity in the planar direction of the electrolyte membrane was calculated from the obtained resistance value, the thickness of the electrolyte membrane, and the distance between terminals. The proton conductivity of the electrolyte membrane of Example 1 under conditions of 80°C and 100% relative humidity was 188 mS / cm, confirming that the electrolyte membrane of Example 1 has good proton conductivity. Hereinafter, the proton conductivity in the examples and comparative examples represents the measured value under conditions of 80°C and 100% relative humidity.

[0182] [Hydrogen Gas Permeability Test] The hydrogen gas permeability of the obtained electrolyte membrane was evaluated according to the gas permeability test method using the isobaric method (JIS K 7126-2). Specifically, first, the electrolyte membrane was installed in a sealed state between the two chambers of the permeation cell. Next, hydrogen gas, the measurement gas, was supplied to one side of the electrolyte membrane, and Ar gas was supplied to the other side as a carrier gas. The relative humidity was adjusted by the humidifier temperature of each supply gas and the cell temperature. The measurement gas that permeated through the electrolyte membrane was supplied to a gas chromatograph together with the carrier gas, and the hydrogen gas permeability was measured from the detection data and flow rate. From the obtained hydrogen gas permeability and the thickness of the electrolyte membrane, the hydrogen gas permeability (unit: cm) was calculated. ３ mm / (cm) ２ The hydrogen gas permeability of the electrolyte membrane in Example 1 was calculated as follows: 0.12 × 10⁻¹⁰ －７ cm ３ mm / (cm) ２ The value was s·kPa, confirming that the electrolyte membrane of Example 1 has excellent gas barrier properties. The hydrogen gas permeability in the following examples and comparative examples is the value measured under conditions of 80°C and 60% relative humidity.

[0183] [Small-Angle X-ray Scattering (SAXS) Measurement] Small-angle X-ray scattering (SAXS) measurements of the electrolyte membrane were performed under the following conditions: dry state (under vacuum) and wet state (immersed in water). Instrument name: NanoSTAR, manufactured by Bruker Japan Voltage / current: 45kV / 120mA X-ray wavelength: Cu Kα-ray Camera length: 104.3cm Exposure time: 60 minutes (dry state), 180 minutes (wet state)

[0184] Figure 1 is a graph showing the small-angle scattering profile obtained from the above measurement. As shown in Figure 1, clear peaks were observed in both the dry and wet states. Furthermore, the peak top position q of the obtained small-angle scattering profile is shown. ｍａｘ Therefore, the interplanar spacing d (= 2π / q) ｍａｘ The interplanar spacing d in the dry and wet states was 3.4 nm and 5.4 nm, respectively. These results confirmed that the electrolyte membrane of Example 1 has a microphase separation structure in both the dry and wet states.

[0185] <Example 2> (Synthesis of polymer (P2)) 1.473 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 1.160 g of the hydrophobic monomer (M4) obtained in Synthesis Example 4, 3.526 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 1.992 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 30 mL of DMSO and 30 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out by heating to 140 °C for 121 hours. After the reaction mixture was allowed to cool to room temperature, it was reprecipitated and purified from 1000 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P2) having the structure represented by the above formula (P2). The yield was 90%. The polymer (P2), measured in the same manner as in Example 1, had a Mn of 33,000, a Mw of 77,000, and a Mw / Mn ratio of 2.3. In the above formula (P2), x was approximately 0.55 (0.51 to 0.59), y was approximately 0.45 (0.41 to 0.49), and n was approximately 20. The polymer (P2) was measured in the same manner as in Example 1. １When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.83–6.88 ppm.

[0186] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 2 (electrolyte membrane made of proton-substituted polymer (P2), thickness 61 μm) was obtained by the same method as in Example 1, except that polymer (P2) was used instead of polymer (P1) and the thickness of the film made of polymer (P2) was adjusted to 61 μm. When the ion exchange capacity was measured by the same method as in Example 1, the IEC of the electrolyte membrane of Example 2 was 2.4 mmol / g.

[0187] (Evaluation) The electrolyte membrane of Example 2 was evaluated using the same method as in Example 1 (proton conductivity evaluation, hydrogen gas permeability test, and SAXS measurement). The proton conductivity was 198 mS / cm, confirming that the electrolyte membrane of Example 2 has good proton conductivity. The hydrogen gas permeability was 0.17 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, confirming that the electrolyte membrane of Example 2 has excellent gas barrier properties. The interplanar spacing d in the dry and wet states, measured by SAXS, was 3.6 nm and 6.1 nm, respectively, confirming that the electrolyte membrane of Example 2 has a microphase separation structure in both the dry and wet states.

[0188] <Comparative Example 1> (Synthesis of Polymer (P3)) 0.498 g of 4,4'-dichlorodiphenylsulfone, 0.532 g of [1,1'-biphenyl]-4,4'-diol, 1.026 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 1.185 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 10 mL of DMSO and 10 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out at 130 °C for 72 hours. After allowing the reaction mixture to cool to room temperature, reprecipitation purification was performed from 300 mL of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P3) having the structure represented by the above formula (P3). The yield was 94%. The polymer (P3), measured in the same manner as in Example 1, had a Mn of 26,000, a Mw of 69,000, and a Mw / Mn ratio of 2.7. In the above formula (P3), x was approximately 0.39 (0.35 to 0.43), y was approximately 0.61 (0.57 to 0.65), and n was approximately 40. The polymer (P3) was measured in the same manner as in Example 1. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.83–6.85 ppm.

[0189] (Preparation of Electrolyte Membrane) The electrolyte membrane of Comparative Example 1 (electrolyte membrane made of proton-substituted polymer (P3), thickness 48 μm) was obtained by the same method as in Example 1, except that polymer (P3) was used instead of polymer (P1) and the thickness of the membrane made of polymer (P3) was adjusted to 48 μm. When the ion exchange capacity was measured by the same method as in Example 1, the IEC of the electrolyte membrane of Comparative Example 1 was 2.5 mmol / g.

[0190] (Evaluation) The electrolyte membrane of Comparative Example 1 was evaluated in the same manner as in Example 1 (proton conductivity evaluation, hydrogen gas permeability test, and SAXS measurement). The proton conductivity was 113 mS / cm, and the hydrogen gas permeability was 0.18 × 10⁻⁶. －７ cm ３ mm / (cm) ２The pressure was s kPa. In the SAXS measurement, no clear scattering peaks were observed in either the dry or wet state.

[0191] <Comparative Example 2> In Comparative Example 2, a commercially available Nafion was used as the evaluation sample. ＴＭ Using NR211 (film thickness 25 μm), various measurements and evaluations (proton conductivity evaluation, hydrogen gas permeability test, and SAXS measurement) were performed using the same method as in Example 1. The IEC was 1.0 mmol / g, the proton conductivity was 130 mS / cm, and the hydrogen gas permeability was 1.03 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s・kPa. The interplanar spacing d in the dry and wet states, as measured by SAXS, was 3.3 nm and 5.3 nm, respectively.

[0192] <Example 3> (Synthesis of polymer (P4)) 1.491 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 2.108 g of the hydrophobic monomer (M5) obtained in Synthesis Example 5, 3.579 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 2.156 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 30 mL of DMSO and 30 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out by heating to 150 °C for 115 hours. After the reaction mixture was allowed to cool to room temperature, it was reprecipitated and purified from 1 L of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain polymer (P4) having the structure represented by the above formula (P4). The yield was 99%. The polymer (P4) measured in the same manner as in Example 1 had a Mn of 30,000, a Mw of 57,000, and a Mw / Mn of 1.9. In the above formula (P4), x was approximately 0.47 (0.43 to 0.51), y was approximately 0.53 (0.49 to 0.57), and n was approximately 15. The polymer (P4) was measured in the same manner as in Example 1. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.78–6.85 ppm.

[0193] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 3 (electrolyte membrane made of proton-substituted polymer (P4), thickness 65 μm) was obtained by the same method as in Example 1, except that polymer (P4) was used instead of polymer (P1) and the thickness of the film made of polymer (P4) was adjusted to 65 μm. When the ion exchange capacity was measured by the same method as in Example 1, the IEC of the electrolyte membrane of Example 3 was 2.2 mmol / g.

[0194] (Evaluation) The electrolyte membrane of Example 3 was evaluated using the same method as in Example 1 (proton conductivity evaluation, hydrogen gas permeability test, and SAXS measurement). The proton conductivity was 192 mS / cm, confirming that the electrolyte membrane of Example 3 has good proton conductivity. The hydrogen gas permeability was 0.19 × 10⁻⁶. －７ cm ３ mm / (cm) ２ The pressure was s·kPa, confirming that the electrolyte membrane of Example 3 has excellent gas barrier properties. The interplanar spacing d in the dry and wet states, measured by SAXS, was 3.5 nm and 5.2 nm, respectively, confirming that the electrolyte membrane of Example 3 has a microphase separation structure in both the dry and wet states.

[0195] <Example 4> (Synthesis of polymer (P5)) 1.635 g of the hydrophobic monomer (M2) obtained in Synthesis Example 2, 1.355 g of the hydrophobic monomer (M3) obtained in Synthesis Example 3, 3.912 g of the hydrophilic monomer (M1) obtained in Synthesis Example 1, and 2.403 g of potassium carbonate were added to a 100 mL three-necked flask equipped with a nitrogen inlet tube, a stirrer, and a Dean-Stark tube, and nitrogen purging was performed. Then, 30 mL of DMSO and 30 mL of cyclohexane were added. After heating to 130 °C and reflux dehydration for 4 hours, the cyclohexane was removed from the Dean-Stark tube. Polymerization was carried out by heating to 150 °C for 116 hours. After cooling to room temperature, 0.018 g of decafluorobiphenyl was added, and polymerization was carried out by heating to 130 °C for 3.5 hours. After the reaction solution was allowed to cool to room temperature, it was reprecipitated and purified from 1 L of IPA, and the solid was recovered by suction filtration. The recovered solid was washed with water and dried under reduced pressure to obtain a polymer (P5) containing multiple polymer units having the structure represented by the above formula (P1), and having decafluorobiphenyl-derived crosslinking groups that bond to three or more of the polymer units. The yield was 92%. The Mn of polymer (P5), measured in the same manner as in Example 1, was 24,000, Mw was 74,000, and Mw / Mn was 3.1. １ When the 1H-NMR spectrum was measured, a peak was observed in the range of 6.78–6.87 ppm.

[0196] (Preparation of Electrolyte Membrane) The electrolyte membrane of Example 4 (electrolyte membrane made of proton-substituted polymer (P5), thickness 60 μm) was obtained by the same method as in Example 1, except that polymer (P5) was used instead of polymer (P1) and the thickness of the film made of polymer (P5) was adjusted to 60 μm. When the ion exchange capacity was measured by the same method as in Example 1, the IEC of the electrolyte membrane of Example 4 was 2.4 mmol / g.

[0197] (Evaluation) The electrolyte membrane of Example 4 was evaluated using the same method as in Example 1 (proton conductivity evaluation, hydrogen gas permeability test, and SAXS measurement). The proton conductivity was 186 mS / cm, confirming that the electrolyte membrane of Example 4 has good proton conductivity. The hydrogen gas permeability was 0.12 × 10⁻⁶.－７ cm ３ mm / (cm) ２ The pressure was s·kPa, confirming that the electrolyte membrane of Example 4 has excellent gas barrier properties. The interplanar spacing d in the dry and wet states, measured by SAXS, was 3.5 nm and 4.9 nm, respectively, confirming that the electrolyte membrane of Example 4 has a microphase separation structure in both the dry and wet states.

[0198]

[0199] This application is based on Japanese Patent Application No. 2024-169434, filed on 27 September 2024, which is incorporated by reference in its entirety. All references cited herein are incorporated as a whole.

Claims

1. The following formula (1): [In formula (1), A １ represents the following formula (a1): (In formula (a1), IExG represents an ion exchange group, L ３ represents a single bond, -O-, -S-, -SO ２ -, or -CO-, x represents an integer from 2 to 10, and * represents a bond. A plurality of IExG may be the same or different from each other, and a plurality of L ３ may be the same or different from each other.) represents a structural unit, and A ２ represents the following formula (a2): (In formula (a2), Ar represents an arylene group having no ion exchange group, L ４ represents a single bond, -O-, -S-, -SO ２ -, or -CO-, y represents an integer from 3 to 20, and * represents a bond. A plurality of Ar may be the same or different from each other, and a plurality of L ４ may be the same or different from each other.) represents a structural unit, and L １ and L ２ each independently represent a single bond, -O-, -S-, or -SO ２ -, n represents an integer from 10 to 100, and * represents a bond. A plurality of A<……> (The content here should be １ but seems to be an incomplete display in the original. I'll continue based on the correct tag.) １ may be the same or different from each other, a plurality of A ２ may be the same or different from each other, a plurality of L １ may be the same or different from each other, a plurality of L ２ may be the same or different from each other. However, at least one of A １ and A<00000? (Here it should be ２ but is unclear in the original) ２ exists in two or more kinds, the difference in x in formula (a1) among a plurality of A １ is within 3, and the difference in y in formula (a2) among a plurality of A ２ is within 5.] A polymer having the structure represented by. It should be noted that there are some unclear or potentially incorrect parts in the original text (such as the incomplete display of tags in some places), but the translation is carried out as accurately as possible based on the existing content.

2. The polymer according to claim 1, wherein the constituent unit represented by formula (a1) comprises at least one group selected from the group consisting of a sulfonic acid group, an alkyl sulfonic acid group, a sulfonimide group, and salts thereof, as the ion exchange group.

3. The polymer according to claim 1 or 2, wherein the constituent unit represented by formula (a2) comprises, as the arylene group, at least one group selected from the group consisting of a phenylene group, a naphthylene group, and a fluorene group, which may have a substituent.

4. The following formula (b1): [In formula (b1), A １ This is synonymous with the above, X １ｂ and X ２ｂ Each of these independently represents a halogen atom. Compound (b1) represented by ] and the following formula (b2): [In formula (b2), A ２ This is synonymous with the above, Z １ｂ and Z ２ｂ Each independently represents a hydroxyl group, a thiol group, a halogen atom, a boronic acid group, an alkylborane group, or a boronic acid ester group. A polymer with compound (b2) represented by ] (where at least one of compound (b1) and compound (b2) is a plurality of A in formula (1) １ The difference of x in formula (a1) in the above formula becomes 3 or less, and multiple A in formula (1) ２ In the above equation (a2), the difference of y is 5 or less. １ Or A ２ The polymer according to any one of claims 1 to 3, which includes two or more compounds of different types, or is an oxide of the polymer.

5. The polymer according to any one of claims 1 to 3, comprising a plurality of polymer units having a structure represented by formula (1), and having a crosslinking group that bonds with three or more of the polymer units.

6. The polymer according to any one of claims 1 to 5, wherein the weight-average molecular weight is 40,000 to 500,000.

7. Use tetramethylsilane as the internal standard. １ The polymer according to any one of claims 1 to 6, having a peak in the range of 6.70 to 6.95 ppm in the 1H-NMR spectrum.

8. The polymer according to any one of claims 1 to 7, wherein the ion exchange capacity is 1.0 to 3.5 mmol / g.

9. An electrolyte material containing the polymer described in any one of claims 1 to 8.

10. An electrolyte membrane containing the polymer described in any one of claims 1 to 8.

11. An electrolyte membrane with a catalyst layer, comprising the electrolyte membrane according to claim 10, and a catalyst layer disposed on one or both sides of the electrolyte membrane.

12. A membrane electrode assembly comprising an electrolyte membrane according to claim 10, and an electrode layer disposed on one or both sides of the electrolyte membrane.

13. A polymer electrolyte fuel cell comprising the membrane electrode assembly described in claim 12.

14. A solid polymer water electrolysis apparatus comprising the membrane electrode assembly described in claim 12.

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