Polymer and method for producing same, compound, composition, electrolyte membrane, water electrolysis device, and method for producing hydrogen

Abstract

The purpose of the present disclosure is to provide: a polymer which has excellent chemical durability, particularly excellent alkali durability; and an electrolyte membrane using the polymer. The electrolyte membrane formed from said polymer is very useful in alkaline water electrolysis application.　This polymer has a constituent unit represented by formula (1). (In formula (1), A is formula (2), B is formula (3), C is formula (4), and n is an integer of 0-20. In formulae (2) to (4), Z represents a halogen-containing group or an ion-exchange group; X represents a bonding position to Y; and l and m each independently represent an integer of 0-20. The symbol * represents a bond.)

Description

Polymers and methods for producing the same, compounds, compositions, electrolyte membranes, water electrolyzers, and methods for producing hydrogen

[0001] This disclosure relates to a polymer with excellent film-forming properties and alkali resistance, and an electrolyte membrane using the same. More specifically, it provides a polymer and an electrolyte membrane particularly excellent for anion exchange membrane type water electrolysis.

[0002] Electrolyte membranes are used in various fuel cells, such as polymer electrolyte fuel cells and solid alkali fuel cells, as well as in various electrolysis technologies such as water electrolysis. These electrolyte membranes are required to have excellent ion conductivity and durability to withstand long-term use.

[0003] The anion exchange membrane water electrolysis method (AEMWE method), a type of water electrolysis, has been proposed as an alternative to the cation exchange membrane water electrolysis method and the alkaline water electrolysis method, and has attracted attention in recent years. In the AEMWE method, an anion exchange membrane (AEM) is used as a membrane separating the anode chamber and the cathode chamber, and pure water or an alkaline aqueous solution is supplied to the anode chamber as the anosolite. In the AEMWE method, pure water or a pure water or alkaline aqueous solution may be supplied to the cathode chamber as the electrodesolite, but it is also possible to use a dry cathode type electrolytic cell in which no electrodesolite is supplied to the cathode chamber. In this dry cathode type, water is supplied to the cathode chamber by permeating from the anode chamber to the cathode chamber through the anion exchange membrane, and hydroxide ions are generated from the water along with hydrogen gas by the cathode reaction.

[0004] Patent Document 1 discloses an anion-conducting polymer for electrolyte membranes that is excellent in chemical durability and solubility in solvents, having a structure in which divalent aromatic groups having ionic functional groups and a bifluorene skeleton are alternately repeated.

[0005] Furthermore, Patent Document 2 reports on an anion-conducting polymer for electrolyte membranes that exhibits excellent chemical durability and ionic conductivity, and on electrolyte membranes using the same. However, there is a need for a polymer that has even greater chemical durability and film strength, as well as excellent film-forming properties.

[0006] Japanese Patent Publication No. 2018-135487 Japanese Patent Publication No. 2021-42351

[0007] In view of the above circumstances, the present disclosure proposes a polymer useful for electrolyte membranes, particularly in anion exchange membrane water electrolysis, and an electrolyte membrane using the same. Specifically, an object of the present disclosure is to provide a polymer for an electrolyte membrane that is excellent in alkali resistance and membrane strength, and further excellent in film-forming properties.

[0008] As a result of intensive studies, the present inventors have found that a polymer having a specific structure can solve the above problems. That is, the present disclosure relates to the following [1] to

[13] . [1] A polymer having a structural unit represented by the following formula (1). [In formula (1), A is the above formula (2), B is the above formula (3), C is the above formula (4), and n is an integer of 0 to 20. In formulas (2) to (4), Z represents a halogeno group or an ion exchange group, X represents a bonding position to Y, and l and m each independently represent an integer of 0 to 20. In addition, * represents a bonding hand.] [2] The polymer according to [1], which has a structural unit represented by the following formula (5). [In formula (5), Ar １ represents the above formula (1), and Ar ２ each independently is a group having a partial structure represented by the following formula (6) at both ends.]] The wavy line represents a bonding hand to Ar １ and bonds to * in formulas (2) to (4). The dotted line indicates that a part of the aromatic ring is omitted. [3] The polymer according to [1] or [2], wherein with respect to formulas (2) to (4), Z is a quaternary ammonium group. [4] A compound represented by the following formula (M1). [In formula (M1), A １ is the above formula (M2), B １ is the above formula (M3), C １ is the above formula (M4), and n1 is an integer of 0 to 20. In formulas (M2) to (M4), R １ is a halogeno group, Z １ is a halogeno group or an ion exchange group, X １ is Y １[5] A composition comprising the compound described in [4] above and a compound represented by the following formula (M11). [In formula (M11), Ar ２ This is a group having a substructure represented by the following formula (6) at both ends. A wavy line represents a bond with a hydrogen atom. A dotted line indicates that part of the aromatic ring has been omitted. [6] A polymer which is a polymer of the composition described in [5]. [7] A method for producing a polymer, comprising the step of reacting the composition described in [5]. [8] An electrolyte membrane comprising the polymer described in any one of [1] to [3] or [6]. [9] A catalyst-coated electrolyte membrane having the electrolyte membrane described in [8] and a catalyst disposed on at least one surface of the electrolyte membrane.

[10] An electrolyte membrane for water electrolysis comprising the electrolyte membrane described in [8].

[11] An anion-exchange type electrolyte membrane for water electrolysis comprising the electrolyte membrane described in [8].

[12] A water electrolysis apparatus comprising the electrolyte membrane described in [8].

[13] A method for producing hydrogen using the electrolyte membrane described in [8].

[0009] Because the polymer of this disclosure has excellent alkali resistance, it can be used to create an electrolyte membrane that is useful in alkaline water electrolysis.

[0010] This figure shows the synthesis scheme of Example 1. Mixture 1 obtained in Example 1 (Step 1-i) １ This figure shows the H-NMR spectrum. This figure shows the HPLC chromatogram of mixture 1 obtained in Example 1 (Step 1-i). This figure shows the HPLC chromatogram of compound IV obtained in Example 1 (Step 1-ii). １ This figure shows the 1H-NMR spectrum of the Cl polymer V obtained in Example 1 (Step 1-iii). １ This figure shows the H-NMR spectrum of TMA polymer VI obtained in Example 1 (Step 1-iv). １ This figure shows the 1H-NMR spectrum of compound I obtained in Comparative Example 1 (Step 2-i). １This figure shows the 1H-NMR spectrum of the Cl polymer VII obtained in Comparative Example 1 (Step 2-iii). １ This figure shows the H-NMR spectrum of TMA polymer VIII obtained in Comparative Example 1 (Step 2-iv). １ This is a diagram showing the 1H-NMR spectrum.

[0011] The following describes an example of an embodiment to which this disclosure applies. This disclosure is not limited to this embodiment, and other embodiments are included insofar as they are consistent with the spirit of this disclosure. In this specification, numerical ranges indicated by "~" include the numerical values ​​described. Furthermore, the numerical values ​​specified are values ​​obtained by the methods described in the embodiments or examples. In addition, unless otherwise noted, each component can be used independently, either alone or in combination of two or more. Also, notations such as "C1-C20" mean that the total number of carbon atoms constituting the group or compound is 1 or more and 20 or less. A constituent unit represented by formula (1) may be referred to as "constituent unit (1)". A compound represented by formula (M1) may be referred to as "compound (M1)". Other constituent units, compounds, substituents, etc. are treated similarly.

[0012] The polymer of this disclosure has a constituent unit represented by formula (1) above. In formula (1), A is formula (2) above, B is formula (3) above, C is formula (4) above, and n is an integer from 0 to 20. In formulas (2) to (4), Z is a halogeno group or an ion exchange group, X represents the bond position with Y, and l and m each independently represent an integer from 0 to 20. Also, * represents a bond.

[0013] [Regarding A, B, and C] A is a structural unit having a fluorene skeleton represented by formula (2), one of which is bonded to B or C at position X, and has a halogen group or an ion exchange group at position Z. l represents an integer from 0 to 20, i.e., it is absent (l=0), or represents the length of the linear alkylene as a group bonded to the carbon atom at position 9 of the fluorene ring, such as methylene (l=1), ethylene (l=2), n-propylene (l=3), n-butylene (l=4), etc. Note that other substituents may be present in this alkylene, for example, halogen groups, alkyl groups, alkoxy groups, etc. are bonded. Preferably, l is 2 to 18, more preferably 3 to 15, particularly preferably 4 to 11, and most preferably 5 to 7. m represents an integer from 0 to 20, meaning it is either absent (m=0), or represents the length of a linear alkylene as another group bonded to the carbon atom at position 9 of the fluorene ring, such as methylene (m=1), ethylene (m=2), n-propylene (m=3), n-butylene (m=4), etc. Note that other substituents may be present in this alkylene, such as halogen groups, alkyl groups, or alkoxy groups. m is preferably 2 to 18, more preferably 3 to 15, particularly preferably 4 to 11, and most preferably 5 to 7. X is bonded to the carbon atom at position 9 of the fluorene ring at position Y in formulas (3) and (4). When m=0, the carbon atom at position 9 of the fluorene ring in formula (2) is directly bonded to the carbon atom at position 9 of the fluorene ring in formula (3) or formula (4). B is a structural unit having the fluorene skeleton represented by formula (3). In equation (3), Y is bonded at the position of X in equation (2). Also, X in equation (3) is bonded at the position of Y in equation (4). C is a constituent unit having a fluorene skeleton represented by equation (4). Y in equation (4) is bonded at the position of X in equation (2) or at the position of X in equation (3). n represents the number of repetitions of B. When n=0 in equation (1), there is no constituent unit represented by equation (3). That is, it becomes an A-C structure, and X in equation (2) directly forms a bond at the position of Y in equation (4). n is an integer from 0 to 20, preferably 0 to 12, more preferably 0 to 6, even more preferably 0 to 3, and particularly preferably 0 or 1.Furthermore, X, Y, Z, l, and m in equations (2) to (4) are independent of each other.

[0014] <Halogeno Group> The halogeno group as Z represents a fluorine group (-F), a chloro group (-Cl), a bromo group (-Br), or an iodine group (-I). Of these, the chloro group and the bromo group are preferred, and the chloro group is particularly preferred.

[0015] <Ion Exchange Groups> The ion exchange group Z is a functional group that has dissociability and is capable of ion exchange, contributing to the ion conduction of this polymer, and can be appropriately selected depending on the application. When imparting proton conductivity to this polymer, an acidic ion exchange group is preferred, and among them, a sulfo group (-SO) is preferred. ３ H group), phosphate group (-H ２ PO ４ A quaternary ammonium group, or a carboxylic acid group (-COOH group), is more preferable, and a sulfo group is even more preferable. Furthermore, when imparting anionic conductivity to the polymer, the ion exchange group is preferably a quaternary ammonium group or an imidazolium group, and a quaternary ammonium group is more preferable. From the viewpoint of alkali resistance, a quaternary alkylammonium group is even more preferable. The alkyl group bonded to the nitrogen atom in the quaternary alkylammonium group is a C1-C6 linear, branched, or cyclic alkyl group, such as a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, or cyclohexyl group. Of these, methyl, ethyl, and propyl groups are preferred. Note that alkyl groups bonded to the nitrogen atom may also form a ring structure, such as an azaadamantyl group or a quinuclidinium group. Furthermore, the counteranion is not limited to a monovalent one, but may be divalent or more. The counteranion is preferably an inorganic anion, specifically a chloride ion (Cl － ), bromide ions (Br － ), iodide ion (I － ), bicarbonate ions (HCO3) ３ － ), carbonate ions (CO ３ ２－ ), hydroxide ion (OH－ Examples include the following. In this polymer, it is preferable that at least one of Z is an ion exchange group.

[0016] In formulas (2) to (4) above, * represents a bond. This bond may be bonded to, for example, a hydrogen atom, a halogen group, or other structural units. However, it is preferable that at least one of the *s is bonded to something other than a halogen group. Other structural units include Ar, which will be discussed later. ２ Ar １ Ar ２ Ar ３ Ar ４ These are some examples, and these may be further bonded with other constituent units. In other words, this polymer may be a three-dimensional polymer. The specific structure of the three-dimensional polymer is complex and difficult to explain directly, but it can be inferred from the precursor composition and its reaction described later.

[0017] [Polymer having a structural unit represented by formula (5)] The polymer of the present disclosure preferably has a structural unit represented by the above formula (5). Among the structural units represented by formula (5), Ar １ This represents the above formula (1), and Ar ２ Each of these is a group having a substructure represented by formula (6) at both ends independently.

[0018] <Ar ２ Regarding > Ar in equation (5) ２ This is a group having the substructure represented by formula (6) above at both ends. In other words, the Ar ２ This is a divalent group containing an aromatic ring with a fluoro group (-F) at the α-position of the terminal carbon atom. Here, Ar ２ The end of is Ar １ This refers to the carbon atom that bonds with Ar. Note that the wavy line indicates Ar. １ This represents the bonding between the two, and the dotted line indicates that part of the aromatic ring has been omitted. Ar ２It is preferable that is one or more selected from the following formulas (a1) to (a9). For example, as in (a1), one ring structure (e.g., a benzene ring) may have two substructures (6), or as in (a2), one C-F bond may constitute two substructures (6). Furthermore, Ar ２ The substructure may be polycyclic, in which case, for example, as in (a3), each of the two ring structures may have one substructure (6), and these rings may be linked directly or via linking groups, or one of the multiple ring structures may have two substructures (6). However, R ａ Each of these is independently a hydrogen atom, a halogen group, or an organic group.

[0019] The above R ａ Examples of halogen groups in include fluoro groups, chloro groups, bromo groups, and iodine groups, and among these, fluoro groups are preferred. Also, the above R ａ Examples of organic groups in this context include linear or branched alkyl groups having 1 to 20 carbon atoms, which may have substituents (e.g., halogen groups) (not including the number of carbon atoms of the substituents).

[0020] Also, Ar ２ More preferably, the following formulas (a10) to (a14) are used. Note that the dashed line represents Ar １ This represents a combination of two things.

[0021] <Other constituent units> The polymer of this disclosure may further have other constituent units. Other constituent units include Ar, which will be described later. ３ Ar ４ These are some examples.

[0022] Ar ３ Ar １ It may also be a polymer that forms repeating units by bonding with Ar ２ It can be a polymer that forms repeating units by bonding with Ar １ and Ar ２ It combines with both of them, for example Ar １ -Ar ３ -Ar ２ This repeating unit can also be constructed. ３Specific examples include the constituent units represented by the following formulas (b1) to (b5). However, R' can be a linear, branched, or cyclic alkyl group of C1 to C18, a linear, branched, or cyclic alkoxy group of C1 to C18, a benzyl group, a phenyl group, a polyether group, an aryl group, an imidazolium group, a piperidinium group, or a pyrrolidinium group, each of which may have substituents such as a hydroxyl group, a carboxyl group, or a halogen group. Of these, a linear alkyl group of C1 to C18 is preferred, a linear alkyl group of C1 to C4 is more preferred, and a methyl group or an ethyl group is even more preferred. Also, n and m represent the number of repetitions and are each an integer of 1 or more, and x represents the molar ratio and is a number from 1 to 99.

[0023] The Ar ４ Ar in polymer ４ -Ar ２ It is a constituent unit that can be included as, and this polymer is, for example, {(Ar ４ -Ar ２ ) ｙ１ - (Ar １ -Ar ２ ) １００－ｙ１ It may also be a random copolymer represented by}, where y represents the molar ratio and is a number from 1 to 99. ４ A concrete example of this is the constituent unit represented by the following formula (7). [In formula (7), R １１ and R １２Each of these is independently a hydrogen atom, a halogeno group, or an ion exchange group, s and t are independently integers from 0 to 20, and * is a bond to another constituent unit. s represents an integer from 0 to 20, i.e., it is absent (s=0), or represents the length of a linear alkylene as a group bonded to the carbon atom at position 9 of the fluorene ring, such as methylene (s=1), ethylene (s=2), n-propylene (s=3), n-butylene (s=4), etc. Note that other substituents may be present in this alkylene, for example, halogeno groups, alkyl groups, alkoxy groups, etc. s is preferably 2 to 18, more preferably 5 to 15, particularly preferably 7 to 12, and most preferably 9 to 11. t represents an integer from 0 to 20, i.e., it is absent (t=0), or represents the length of a linear alkylene as another group bonded to the carbon atom at position 9 of the fluorene ring, such as methylene (t=1), ethylene (t=2), n-propylene (t=3), n-butylene (t=4), etc. Note that other substituents may be present in this alkylene, for example, halogeno groups, alkyl groups, alkoxy groups, etc. Preferably, t is 2 to 18, more preferably 5 to 15, particularly preferably 7 to 12, and most preferably 9 to 11.

[0024] Preferred polymers of this disclosure are exemplified in Tables 1 and 2 below. However, the disclosure is not limited to these. In the tables, p represents the number of repeats, which is usually around 2 to 20. Also, * represents a bond.

[0025]

[0026] The polymers of this disclosure preferably have a weight-average molecular weight of 100,000 or more. The weight-average molecular weight can be measured by GPC (gel permeation chromatography) under the following conditions. Apparatus: EcoSEC-Elite (manufactured by Tosoh Corporation) Column: TSKgel SuperMultiporeHZ-M, 3 columns (manufactured by Tosoh Corporation) Measurement temperature: 40°C Sample solution: 0.12 wt% THF solution Mobile phase: THF (tetrahydrofuran) Solution injection volume: 10 μL Flow rate: 0.4 mL / min Detection device: Refractive index detector Reference material: Standard polystyrene (TSKgel standard polystyrene) (manufactured by Tosoh Corporation, 8 samples (weight-average molecular weight: 1,110,000, 397,000, 189,000, 37,200, 15,700, 5,430, 3,120, 589))

[0027] The lower limit of the weight-average molecular weight of the polymers disclosed herein may be around 100,000, but more preferably 180,000, 190,000, 200,000, and 220,000, respectively, and particularly preferably 240,000. The upper limit of the weight-average molecular weight of the polymers may be around 400,000, more preferably 380,000, 360,000, 350,000, 340,000, 320,000, and 300,000, respectively, and particularly preferably 280,000. Therefore, the most preferred weight-average molecular weight of the polymers is 240,000 to 280,000.

[0028] [Compound] The compound of this disclosure is represented by the following formula (M1). This compound (M1) is a monomer corresponding to the constituent unit (1) of the polymer. The polymer can be suitably produced by using this compound (M1). [In formula (M1), A １ The above formula (M2) is given by B １ The above formula (M3) is given by C １ The above equation (M4) is given by n1 being an integer from 0 to 20. In equations (M2) to (M4), R １ is a halogeno group, Z １ is a halogen group or an ion exchange group, and X １ is Y １represents the bonding position, and l1 and m1 each independently represent an integer of 0 to 20.]]

[0029] In formula (M1), A １ , B １ , C １ and n1 each correspond to A, B, C and n in formula (1), respectively. The preferred range of n1 is the same as that of n described above. In formulas (M2) to (M4), X １ , Y １ , m1 and l1 correspond to X, Y, m and l in formulas (2) to (4), respectively. X １ , Y １ the preferred configurations of m1 and l1 are the same as those of X, Y, m and l described above. In formulas (M2) and (M4), Z １ corresponds to Z in formulas (2) and (4), and is a halogeno group or an ion exchange group. Z １ specific examples thereof include the same groups as those described above for Z. From the viewpoint of improving the yield of the polymer, Z １ is preferably a halogeno group, more preferably a chloro group or a bromo group, and still more preferably a chloro group. In formulas (M2) to (M4), R １ is a halogeno group, and is a site that becomes a bonding site during polymerization. Examples of R １ include a fluoro group, a chloro group, a bromo group, and an iodo group, with a chloro group or a bromo group being preferred. Further, from the viewpoint of suppressing side reactions during polymerization, R １ and Z １ are preferably halogeno groups different from each other. Specific examples of the compound (M1) are shown in Table 3.

[0030] [Composition] The composition of the present disclosure comprises the compound (M1) and a compound represented by the following formula (M11). The present composition is a precursor composition suitable for producing a polymer having the structural unit (5). After polymerization, the compound (M1) corresponds to Ar １ in formula (5), and the compound (M11) corresponds to Ar ２ in formula (5). In formula (M11), Ar ２ is a group having the partial structure represented by formula (6) above at both terminals thereof.

[0031] Ar in formula (M11) ２ is the same as Ar in formula (5) ２ , and the preferred embodiments are also the same. Specific examples of the compound (M11) include compounds obtained by replacing the wavy line with a hydrogen atom in formulas (a1) to (a9), and compounds obtained by replacing the wavy line with a hydrogen atom in formulas (a10) to (a14) are preferred.

[0032] In addition, the present composition may further contain other compounds. Examples of other compounds include compounds that become the aforementioned structural unit Ar after polymerization ３ , Ar ４ . Examples of the compound that becomes Ar ４ include a compound represented by the following formula (M7). wherein in formula (M7), R １１’ and R １２’ are each independently a hydrogen atom, a halogeno group, or an ion exchange group, and R ２１ and R ２２ are halogeno groups. s1 and t1 are each independently an integer of 0 to 20.

[0033] The halogeno group and the ion exchange group in R １１’ and R １２’ are the same as Z in the aforementioned formulas (M2) and (M4) １ , and the preferred embodiments are also the same. The halogeno group in R ２１ and R ２２ is the same as R in the aforementioned formulas (M2) to (M4) １ , and the preferred embodiments are also the same.

[0034] When the compound (M7) is used, the molar ratio of the compound (M1) to the compound (M7) (M1:M7) in the present composition is preferably from 5:95 to 99:1, more preferably from 10:90 to 95:5.

[0035] [Method for producing monomer] The method for producing the aforementioned compound (M1) is not particularly limited, and for example, it can be obtained by reacting a compound represented by the following formula (P1) with a compound represented by the following (P2). Z ２ -(CH ２ )ｎ２ -Z ２ (P2) However, R １ is a halogeno group, Z ２ is a halogen group, R １ and Z ２ These are distinct halogen groups, and n2 is an integer from 1 to 20.

[0036] R in equation (P1) １ This is the same as in equations (M2) to (M4), and the preferred embodiment is also the same. Z in equation (P2) ２ This is Z in equations (M2) to (M4). １ It is similar to a halogen group, and the preferred embodiment is also similar. In formula (P2), n2 is CH ２ This represents the number of repetitions and corresponds to l1 and m1 in equations (M2) to (M4). The preferred range for n2 is the same as that for l1 and m1.

[0037] The above compound (M1) can be obtained, for example, by preparing an aqueous solution containing compound (P1) and compound (P2), and reacting compound (P1) and compound (P2) by heating in the presence of a base. A phase transfer catalyst such as n-tetrabutylammonium chloride may be used as needed to dissolve compound (P1) and compound (P2). The above reaction yields a mixture containing different compounds (M1) with n1 and the above compound M7 (M7). If necessary, the specific compound (M1) with n1 may be purified.

[0038] [Method for producing the polymer] The method for producing the polymer is not particularly limited, but for example, a polymer of the composition, i.e., the polymer of the disclosure, can be obtained by reacting the composition in a solvent. The composition can be prepared by mixing the mixture obtained by the monomer production method with the compound (M11).

[0039] The reaction between compound (M1) and compound (M11) involves, for example, a Pd complex, a ligand, and a carboxylic acid (RCO). ２The reaction can be carried out in a solvent in the presence of H and a base. Various Pd complexes, ligands, carboxylic acids, bases, and solvents can be used in this reaction, but among these, Pd is particularly... ２ (dba) ３ CHCl ３ , P(o-C) ６ H ４ -OMe) ３ , pivalic acid (PivOH), Cs ２ CO ３ It is preferable to use and dryTHF (tetrahydrofuran), respectively. Here, dba means dibenzylideneacetone. The reaction time and reaction temperature in the above reaction step can also be set as appropriate, for example, 1 to 48 hours and 80 to 140°C. Next, Z １ If the group is a halogeno group, the polymer of this disclosure can be obtained by substituting it with a desired ion exchange group.

[0040] Specific examples of the production of the monomer and polymer will be explained with reference to Figure 1. The polymer can be produced, for example, by the following steps (i) to (iv). However, the production method and raw material compounds are not limited to these. (1) Step (i): 2,7-dibromofluorene and 1,6-dichlorohexane are reacted in the presence of sodium hydroxide and n-tetrabutylammonium chloride to obtain mixture I (a mixture of compounds I, II, and III) shown in Figure 1. At this time, by adjusting the amount of raw materials used, compounds II and III can be obtained in fixed amounts. When isolating only compounds II and III, silica gel column chromatography or the like can be used, but in the electrolyte membrane of this disclosure, they may be used as a mixture. (2) Step (ii): 2,7-dibromofluorene and 1-bromooctane are reacted in the presence of sodium hydroxide and n-tetrabutylammonium chloride to obtain compound IV shown in Figure 1. (3) Step (iii): Mixture I, compound IV, and 1,2,4,5-tetrafluorobenzene are reacted using a palladium catalyst in the presence of dry THF, pivalic acid, cesium carbonate, and tris(2-methoxyphenyl)phosphine to obtain Cl polymer V. (4) Step (iv): The Cl polymer V obtained in step (iii) is reacted with a trimethylamine methanol solution to convert the Cl groups into trimethylamino groups (the counteranion is Cl). － ) is substituted to obtain TMA polymer VI.

[0041] [Electrolyte membrane] The electrolyte membrane of this disclosure is characterized by containing the polymer of this disclosure and is an electrolyte membrane with excellent alkali resistance and membrane strength.

[0042] The electrolyte membrane of this disclosure may be a single film formed by depositing the polymer of this disclosure, or it may be a composite membrane containing a reinforcing material. By using a composite membrane with a reinforcing material, the electrolyte membrane has improved not only in chemical durability but also in mechanical strength, resulting in a more durable electrolyte membrane. Examples of composite membranes include a multilayer membrane comprising a substrate and a layer containing the polymer, and a pore-filling membrane comprising a porous substrate and the polymer filled inside the porous substrate. From the viewpoint of easily improving mechanical strength, a pore-filling membrane is preferred.

[0043] As the base material used as the reinforcing material, a porous base material is preferred. From the viewpoint of improving ionic conductivity, it is preferable that at least a portion of the pores of the porous base material form through-holes. Examples of porous base materials include porous films, nonwoven fabrics, and meshes. The porous base material used in the porous filling membrane may be any base material having pores capable of holding polymers. From the viewpoint of providing mechanical strength, the form of the base material is preferably a nonwoven fabric or a porous film, and more preferably a porous film. The porosity of the porous base material (= volume of voids / bulk volume × 100 (%)) is preferably 30 to 95%, more preferably 40 to 80%, and even more preferably 45 to 70%, from the viewpoint of balancing mechanical strength and ionic conductivity. The film thickness of the porous base material is preferably 5 to 200 μm, more preferably 7 to 100 μm, and even more preferably 10 to 50 μm, from the viewpoint of balancing mechanical strength and ionic conductivity. Furthermore, the pore size of the porous substrate is preferably 10 to 10,000 nm in average diameter, and more preferably 10 to 1,000 nm, from the viewpoint of filling and holding the polymer and mechanical strength. From the viewpoint of chemical durability, especially stability in alkali, a polyolefin-based porous substrate is preferred for the porous substrate material. Another advantage of using a polyolefin-based porous substrate is that it is easier to fill with polyarylene polymer, especially high molecular weight polyarylene polymer with a weight-average molecular weight of 100,000 or more. Among polyolefin-based porous substrates, polyethylene porous substrates, polypropylene porous substrates, or polytetrafluoroethylene porous substrates are preferred from the viewpoint of mechanical strength and chemical resistance. Among polyethylene porous substrates, ultra-high molecular weight polyethylene (for example, with a weight-average molecular weight of 1,000,000 or more) porous substrates are preferred.

[0044] Methods for filling porous substrates with this polymer include, for example, preparing a solution of the polymer and using methods such as dipping, spraying, spin coating, or barcoding. After impregnating the porous substrate with the polymer solution, a pore-filling film can be obtained by drying. The filling of the porous substrate with this polymer can be confirmed, for example, by Raman analysis.

[0045] [Applications of Electrolyte Membranes] <Catalyst-Coated Electrolyte Membranes> The electrolyte membrane of this disclosure can be used as a catalyst-coated electrolyte membrane equipped with a catalyst on one or both sides thereof. For example, in an electrolyte membrane used for water electrolysis, an anode catalyst is arranged as the anode on one side and a cathode catalyst is arranged as the cathode on the other side. The anode catalyst is preferably a metal or a metal alloy. The metal or metal alloy can be appropriately selected from known materials, and examples include platinum, cobalt, nickel, palladium, iron, silver, gold, copper, iridium, molybdenum, rhodium, chromium, tungsten, manganese, ruthenium, compounds of these metals, metal oxides, and alloys containing two or more of these metals. The cathode catalyst is preferably a metal or a metal alloy. The metal or metal alloy can be appropriately selected from known materials, such as platinum, cobalt, nickel, palladium, iron, silver, gold, copper, iridium, molybdenum, rhodium, chromium, tungsten, manganese, ruthenium, compounds of these metals, metal oxides, and alloys containing two or more of these metals. Methods for forming the catalyst layer include pulse spray coating, ultrasonic spray coating, die coater coating, bar coater coating, and electrode transfer coating. Depending on the coating method, a drying step may also be included.

[0046] <Water Electrolyte Membrane, Electrolyte Membrane for Anion Exchange Water Electrolysis, and Water Electrolyzer> The catalyst-coated electrolyte membrane of this disclosure has water electrolysis performance, particularly anion exchange water electrolysis performance. An electrochemical cell is created by forming a catalyst layer on the cathode side of an electrolyte membrane having anion exchange groups, in which a metal powder with hydrogen generation ability is dispersed in an ionomer, and forming a catalyst layer on the anode side, in which a metal powder with oxygen generation ability is dispersed in an ionomer. Anion exchange membrane water electrolysis performance means that when an alkaline solution is passed through the electrochemical cell, and current is passed from a power source to the electrochemical cell containing the electrolyte membrane and ionomer, which have been ion-exchanged with OH ions by the alkaline solution, water electrolysis is possible without a large voltage increase. Specifically, platinum-supported carbon or platinum-ruthenium alloy-supported carbon is commonly used as the hydrogen generation catalyst, and iridium oxide is commonly used as the oxygen generation catalyst. When 1 mol / L potassium hydroxide is used in the alkaline solution, the electrolysis performance when the electrochemical cell is at 80°C is 1 A / cm ２ The voltage should be 2.0 V or less, but preferably 1.7 V to 1.8 V, and particularly preferably 1.78 V or less. Ion exchange capacity represents the amount of ions that the ion exchange resin can adsorb. A higher value indicates higher ionic conductivity, but also increases the water content, causing the electrolyte membrane to swell and reducing gas barrier properties. Therefore, a value of 1.0 mmol / g to 2.0 mmol / g is preferred, particularly preferably 1.2 mmol / g to 1.9 mmol / g, and most preferably 1.3 to 1.7 mmol / g. The water electrolysis apparatus equipped with the anion exchange type water electrolysis electrolyte membrane can be used as an excellent hydrogen generator because it has particularly high alkali resistance.

[0047] The present invention will be described in more detail below with reference to examples. However, these descriptions do not limit the present invention, and modifications can be made as appropriate without departing from the spirit of the invention.

[0048] [Example 1] A polymer having repeating units represented by formula (1) described above was synthesized according to schemes 1 and 2 shown in Figure 1. In the following, for example, step (i) of scheme 1 will be referred to as step (1-i), and other steps will follow the same convention. In schemes 1 and 2 and in each polymer described later, n represents the number of repeating units of each constituent unit.

[0049] <Step (1-i): Synthesis of Mixture I> In a two-necked flask, 600 mL of aqueous solution of sodium hydroxide (200 g) and 7.61 g of n-tetrabutylammonium chloride were added and stirred under nitrogen. Next, a solution prepared by dissolving 35.5 g of 2,7-dibromofluorene (110 mmol) in 170 g of 1,6-dichlorohexane (1.1 mol) while heating was added to the two-necked flask using a syringe. The mixture was then reacted at 90°C under nitrogen for 90 minutes, and the resulting reaction solution was cooled to room temperature (25°C). The organic phase in the cooled reaction solution was extracted with 300 mL of dichloromethane using a separatory funnel and washed with 50 mL of 1 M hydrochloric acid and 200 mL of water (2 x 2). The dichloromethane in the obtained organic phase was removed using an evaporator, and then unreacted 1,6-dichlorohexane was removed under reduced pressure at 90°C. Heptane (100 mL) and activated carbon (5 g) were added to the resulting residue and stirred in a 40°C water bath for 60 minutes. After removing the activated carbon by vacuum filtration, the heptane was distilled off to obtain the target mixture I (47 g, compound I LC purity 86.0%, compound II LC purity 12.5%, compound III LC purity 1.5%). １ The H-NMR spectrum is shown in Figure 2, and the HPLC chromatogram is shown in Figure 3. １ H-NMR (400MHz, CDCl ３): δ7.52 (2H, d), δ7.49 (0.13H, s), δ7.47-7.43 (4H, m), δ7.37 (0.26H, d), δ3.42 (4Ht), δ1.93 (4H , m), δ1.60 (4H, m), δ1.19 (4H, m), δ1.08 (4H, m), δ0.81 (0.26H, s), δ0.58 (4H, m), δ0.42 (0.26H, s) LC (flow rate: 0.4 mL / min, Mobile phase A: Acetonitrile / THF (50 / 50), Mobile phase B: Ammonium acetate 5 mM, Gradient: A / B (80 / 20) → A / B (99 / 1) 20 min → A / B (99 / 1) 10 min)

[0050] <Step (1-ii): Synthesis of Compound IV> In a two-necked flask, 600 mL of aqueous solution of sodium hydroxide (200 g) and 3.53 g of n-tetrabutylammonium chloride were added and stirred under nitrogen. Next, a solution prepared by dissolving 35.5 g of 2,7-dibromofluorene (110 mmol) in 50.8 g of 1-bromooctane (263 mmol) while heating was added to the two-necked flask using a syringe. The reaction was then carried out at 90°C under nitrogen for 90 minutes, after which the resulting reaction solution was cooled to room temperature (25°C). The organic phase in the cooled reaction solution was extracted with dichloromethane (300 mL) using a separatory funnel and washed with 50 mL of 1 M hydrochloric acid and water (200 mL x 2). The dichloromethane in the obtained organic phase was removed using an evaporator, and then unreacted 1-bromooctane was removed under reduced pressure at 90°C. The resulting residue was subjected to silica gel column chromatography (eluent: hexane:chloroform = 9:1) to obtain the target compound IV (55.7 g, 102 mol). １ The 1H-NMR spectrum is shown in Figure 4. １ H-NMR (400MHz, CDCl ３ ): δ7.52 (2H, d), δ7.49 (0.13H, s), δ7.47-7.43 (4H, m), δ7.37 (0.26H, d) δ1.93 (4H, m), δ1.23-1.06 (20H, m), δ0.84 (6H, t), δ0.59 (4H, m)

[0051] <Step (1-iii): Synthesis of Cl polymer V> In a 50 mL two-necked round-bottom flask, combine mixture I (2.24 g, 4.0 mmol), compound IV (1.46 g, 2.66 mmol), pivalic acid (6.8 g, 6.66 mmol), and Cs ２ CO ３ (6.5g, 20.0mmol), P(o-C ６ H ４ -OMe) ３ (51.6 mg, 146 μmol), Pd ２ (dba) ３ - CHCl ３ (33.6 mg, 36.6 μmol) was added. 2 mL of dehydrated THF was added and incubated for 10 minutes. ２ A substitution was performed. N ２ The substitution was stopped, and 1,2,4,5-Tetrafluorobenzene (1.0 g, 6.66 mmol) was dissolved in 1.0 mL of anhydrous THF and added. The mixture was stirred at room temperature under nitrogen for 30 minutes, and then reacted at 95°C for 24 hours. The resulting solid was dissolved in 200 mL of chloroform, washed with 1 M hydrochloric acid, and then washed twice with water. After solvent removal, it was dissolved in chloroform, reprecipitation in methanol, and stirred for a while. After filtration, it was vacuum-dried at 75°C for 3 hours to obtain Cl polymer V (1.92 g). １ The 1H-NMR spectrum is shown in Figure 5. Compared to the Cl-polymer VII in Figure 8, the aromatic peak at δ 7.55 is broadened, and the number of protons in the peaks originating from alkyl groups at δ 2.0-0.8 has increased, confirming that the Cl-polymer V contains compounds I, II, and III. １ H-NMR (400MHz, CDCl ３ ): δ7.90 (2H, d), δ7.55 (4H, br), δ3.43 (2.71H, t), δ2.05 (3.5H, br), δ1.61 (3.5H, m), δ1.22 (19H, m), δ0.83 (13H, m) Molecular weight (GPC) of Cl polymer V: Mw = 140,000, Mw / Mn = 3.46

[0052] <Step (1-iv): Synthesis of TMA Polymer VI> Cl polymer V (200 mg) was dissolved in chlorobenzene (20 mL). If there were any insoluble components, they were filtered out beforehand. 2 mL of 25% by mass trimethylamine methanol solution was added to the resulting solution and stirred at 100°C for 3 hours. Then, 10 mL of dimethyl sulfoxide was added and stirred for another 3 hours. After removing most of the chlorobenzene from the reaction mixture using an evaporator, 20 mL of dimethyl sulfoxide and 3 mL of 25% by mass trimethylamine methanol solution were added and stirred at 100°C for 2 hours to complete the reaction. The dimethyl sulfoxide in the resulting reaction mixture was removed using an evaporator at 70°C and allowed to dry. Water was added to the dried residue and filtered. Water was added to the resulting solid and stirred at 80°C. Subsequently, the mixture was cooled to room temperature (25°C), filtered, and the resulting solid was vacuum-dried to obtain the target TMA polymer VI (203 mg). １ The 1H-NMR spectrum is shown in Figure 6. １ H-NMR (400MHz, CD ３ OD): δ8.05 (2H, d), δ7.59 (4H, m), δ3.21 (4H, t), δ3.04 (18H, s) δ2.21 (2H, br), δ1.62 (4H, br), δ1.23 (24H, br) δ0.81 (8H, br) １９ F-NMR (400MHz, CD ３ OD): δ-146.1

[0053] [Comparative Example 1] <Step (2-i): Synthesis of Compound I> In a two-necked flask, 600 mL of aqueous solution of sodium hydroxide (200 g) and n-tetrabutylammonium chloride (556 mg) were added and stirred under nitrogen. Next, a solution prepared by dissolving 2,7-dibromofluorene (6.48 g, 20 mmol) in 1,6-dichlorohexane (31.0 g, 200 mmol) while heating was added to the two-necked flask using a syringe. The reaction was then carried out at 90°C under nitrogen for 90 minutes, and the resulting reaction solution was cooled to room temperature (25°C). The organic phase in the cooled reaction solution was extracted with dichloromethane (300 mL) using a separatory funnel and washed with 1 M hydrochloric acid (50 mL) and water (200 mL x 2). The dichloromethane in the obtained organic phase was removed using an evaporator, and then unreacted 1,6-dichlorohexane was removed under reduced pressure at 90°C. The resulting residue was subjected to a silica gel column (eluent:hexane:chloroform = 9:1) to obtain the target compound I (7.63 g, 13.6 mmol). １ The 1H-NMR spectrum is shown in Figure 7. １ H-NMR (400MHz, CDCl ３ ): δ7.52 (2H, d), δ7.47-7.43 (4H, m), δ3.42 (4H, t) δ1.93 (4H, m), δ1.60 (4H, m), δ1.19 (4H, m), δ1.08 (4H, m), δ0.58 (4H, m)

[0054] <Step (2-ii): Synthesis of Compound IV> Compound IV was obtained by the procedure described in Example 1. <Step (2-iii): Synthesis of Cl-polymer VII> Compound I (2.24 g, 4.0 mmol), Compound IV (1.46 g, 2.66 mmol), Pivalic acid (6.8 g, 6.66 mmol), Cs ２ CO ３ (6.5g, 20.0mmol), P(o-C ６ H ４ -OMe) (51.6 mg, 146 μmol), Pd ２ (dba) ３ - CHCl ３(33.6 mg, 36.6 μmol) was added. 2 mL of dehydrated THF was added and incubated for 10 minutes. ２ A substitution was performed. N ２ The substitution was stopped, and 1,2,4,5-Tetrafluorobenzene (1.0 g, 6.66 mmol) was dissolved in 1.0 mL of anhydrous THF and added. After stirring for 30 minutes under nitrogen at room temperature, the reaction was carried out at 95°C for 24 hours. The obtained solid was dissolved in 200 mL of chloroform, washed with 1 M hydrochloric acid, and then washed twice with water. After solvent removal, it was dissolved in chloroform, reprecipitation in methanol, and stirred for a while. After filtration, it was vacuum dried at 75°C for 3 hours to obtain Cl polymer VII (1.92 g). １ The 1H-NMR spectrum is shown in Figure 8. １ H-NMR (400MHz, CDCl ３ δ7.90 (2H, d), δ7.55 (4H, s), δ3.43 (2.61H, t), δ2.05 (3H, br), δ1.61 (3H, m), δ1.22 (14H, m), δ0.83 (6H, m) Molecular weight of Cl polymer VII (GPC): Mw = 140,000, Mw / Mn = 3.03

[0055] <Step (2-iv): Synthesis of TMA Polymer VIII> Cl polymer VII (200 mg) was dissolved in chlorobenzene (20 mL). 25% by mass trimethylamine methanol solution (2 mL) was added to the resulting solution and stirred at 100°C for 3 hours. Then, dimethyl sulfoxide (10 mL) was added and stirred for a further 3 hours. After removing most of the chlorobenzene from the reaction mixture using an evaporator, dimethyl sulfoxide (20 mL) and 25% by mass trimethylamine methanol solution (3 mL) were added and stirred at 100°C for 2 hours to complete the reaction. The dimethyl sulfoxide in the resulting reaction mixture was removed at 70°C using an evaporator and allowed to dry. Water was added to the dried residue and filtered. Water was added to the resulting solid and stirred at 80°C. Then, the mixture was cooled to room temperature (25°C), filtered, and the resulting solid was vacuum dried to obtain the target TMA polymer VIII (203 mg). TMA Polymer VIII １ The 1H-NMR spectrum is shown in Figure 9. １H-NMR (400MHz, CD ３ OD): δ8.05 (2H, d), δ7.59 (4H, m), δ3.21 (4H, t), δ3.04 (18H, s), δ2.21 (2H, br), δ1.62 (4H, br), δ1.23 (24H, br), δ0.81 (8H, br) １９ F-NMR (400MHz, CD ３ OD): δ-146.1

[0056] [Manufacture of Electrolyte Membrane] 1.5 g each of TMA polymer VI and TMA polymer VIII obtained in Example 1 and Comparative Example 1 were diluted with methanol to create a coating solution. This solution was applied to a release film (SP2002) manufactured by Toyo Cross Co., Ltd. using an applicator and dried to obtain an electrolyte membrane. The film thickness of each electrolyte membrane was 59 μm for TMA polymer VI and 35 μm for TMA polymer VIII.

[0057] [Alkali Durability Test of Electrolyte Membranes] Electrolyte membranes prepared from TMA polymer VI and TMA polymer VIII were dried under reduced pressure at 120°C for 4 hours. The prepared electrolyte membranes were placed in 20 mL of 1 M KOH aqueous solution in high-density polyethylene containers and heated in a constant temperature bath at 80°C and 95°C, respectively. The state of the membranes was visually observed after 200 hours of heating and evaluated. A state where the alkaline solution turned colored was considered to be the start of membrane dissolution, and a state where the membrane disappeared was considered to be complete dissolution. The results are shown in Table 4.

[0058]

[0059] The evaluation results were categorized as follows: ◎ No change in the membrane, ○ The membrane swells, △ 1M KOH becomes discolored, × The membrane dissolves. As shown in Table 4, the electrolyte membrane prepared from polymer VI synthesized in Example 1 did not dissolve in 1M KOH at 80°C and 95°C, and no discoloration was observed. On the other hand, the electrolyte membrane prepared from polymer VIII synthesized in Comparative Example 1 showed discoloration of KOH at 80°C, and the membrane dissolved at 95°C. From the above results, it was found that the polymer in the example containing the compound of the present invention has improved alkali resistance compared to the comparative example polymer.

[0060] Because the polymer of this disclosure has excellent alkali resistance, it can be used to create an electrolyte membrane that is useful in alkaline water electrolysis.

[0061] This application claims priority based on Japanese Patent Application No. 2025-037905, filed on 11 March 2025, and incorporates all of its disclosures herein.

Claims

1. A polymer having a constituent unit represented by the following formula (1). [In formula (1), A is formula (2) above, B is formula (3) above, C is formula (4) above, and n is an integer from 0 to 20. In formulas (2) to (4), Z is a halogeno group or an ion exchange group, X represents the bond position with Y, and l and m each independently represent an integer from 0 to 20. Also, * represents a bond.] 2. The polymer according to claim 1, having a constituent unit represented by the following formula (5). [In formula (5), Ar １ This represents the above formula (1), and Ar ２ Each of these groups independently has a substructure represented by the following formula (6) at both ends. The wavy line is Ar １ This represents a bond with and combines with * in equations (2) to (4). The dotted line indicates that part of the aromatic ring has been omitted.

3. The polymer according to claim 1, wherein Z is a quaternary ammonium group with respect to formulas (2) to (4).

4. A compound represented by the following formula (M1). [In the formula (M1), A １ is the above formula (M2), and B １ is the above formula (M3), and C １ is the above formula (M4), and n1 is an integer of 0 to 20. In the formulas (M2) to (M4), R １ is a halogeno group, and Z １ is a halogeno group or an ion exchange group, and X １ represents the bonding position to Y １ , and l1 and m1 each independently represent an integer of 0 to 20. ] 5. A composition comprising the compound described in claim 4 and a compound represented by the following formula (M11). [In formula (11), Ar ２ This is a group having a substructure represented by the following formula (6) at both ends. The wavy lines represent bonds with hydrogen atoms. The dotted lines indicate that part of the aromatic ring has been omitted.

6. A polymer which is a polymer of the composition described in claim 5.

7. A method for producing a polymer, comprising the step of reacting the composition described in claim 5.

8. An electrolyte membrane comprising the polymer according to any one of claims 1 to 3 or 6.

9. A catalyst-coated electrolyte membrane comprising an electrolyte membrane according to claim 8 and a catalyst disposed on at least one surface of the electrolyte membrane.

10. An electrolyte membrane for water electrolysis comprising the electrolyte membrane described in claim 8.

11. An electrolyte membrane for anion exchange water electrolysis, comprising the electrolyte membrane described in claim 8.

12. A water electrolysis apparatus comprising the electrolyte membrane described in claim 8.

13. A method for producing hydrogen using the electrolyte membrane described in claim 8.

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