JP2013076064A - Aromatic sulfonimide derivative, sulfonimide group-containing polymer, polyelectrolyte material using the same, polyelectrolyte molded product, and polymer electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyelectrolyte material having excellent proton conductivity in a low-humidity condition, exhibiting excellent mechanical strength and chemical stability, and capable of achieving high output and excellent physical durability when used for a polymer electrolyte fuel cell; and a polyelectrolyte molded product and a polymer electrolyte fuel cell using the polyelectrolyte material.SOLUTION: The polyelectrolyte material consists of a polymer containing a structural unit represented by formula (P1). The polyelectrolyte molded product and the polymer electrolyte fuel cell using the polyelectrolyte material are also provided. In the formula: Rand Rare each independently a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups; and Mand Mare cationic species selected from hydrogen, metal cations, and an ammonium cation.

Description

  The present invention relates to an aromatic sulfonimide derivative and a sulfonimide group-containing polymer using the same, and in particular, has excellent proton conductivity even under low humidification conditions, and has excellent mechanical strength and chemical properties. The present invention relates to a polymer electrolyte material excellent in practical use capable of achieving physical stability and physical durability, and a polymer electrolyte molded body and a solid polymer fuel cell using the material.

  BACKGROUND ART A fuel cell is a kind of power generation device that extracts electrical energy by electrochemically oxidizing a fuel such as hydrogen or methanol, and has recently attracted attention as a clean energy supply source. In particular, the polymer electrolyte fuel cell has a standard operating temperature as low as around 100 ° C. and a high energy density, so that it is a relatively small-scale distributed power generation facility, a mobile power generator such as an automobile or a ship. As a wide range of applications are expected. It is also attracting attention as a power source for small mobile devices and portable devices, and is expected to be installed in mobile phones and personal computers in place of secondary batteries such as nickel metal hydride batteries and lithium ion batteries.

  In a fuel cell, an anode electrode and a cathode electrode in which a reaction responsible for power generation occurs, and a polymer electrolyte membrane serving as a proton conductor between the anode and the cathode are sometimes referred to as a membrane electrode assembly (hereinafter, abbreviated as MEA). ) And a cell in which this MEA is sandwiched between separators is configured as a unit. The polymer electrolyte membrane is mainly composed of a polymer electrolyte material. The polymer electrolyte material is also used as a binder for the electrode catalyst layer.

  The required characteristics of the polymer electrolyte membrane include firstly high proton conductivity, and it is particularly necessary to have high proton conductivity even under high temperature and low humidification conditions. In addition, since the polymer electrolyte membrane also functions as a barrier that prevents direct reaction between fuel and oxygen, low permeability of the fuel is required. Other examples include chemical stability to withstand a strong oxidizing atmosphere during fuel cell operation, mechanical strength and physical durability to withstand repeated thinning and swelling and drying.

Since proton conductivity depends on the water content of the membrane, it was necessary to maintain high humidity conditions in order to achieve high power generation performance as a fuel cell. Along with this, there was a problem that the load on the humidifier increased, and under freezing point, water in the conductive membrane involved in proton conduction was frozen, so that proton conductivity was greatly reduced and power generation could not be performed. .

Conventionally, Nafion (registered trademark) (manufactured by DuPont), which is a perfluorosulfonic acid polymer, has been widely used for polymer electrolyte membranes. Nafion (registered trademark) exhibits high proton conductivity even under low humidification conditions due to the high acid dissociable perfluorosulfonic acid group, but on the other hand, it is very expensive because it is produced through multi-step synthesis. There was a problem that the fuel crossover was large. In addition, problems such as loss of mechanical strength and physical durability of the membrane due to swelling and drying, problems of low softening point and inability to use at high temperatures, problems of disposal treatment after use and difficulty in recycling materials are pointed out. It has been.

  In order to overcome such drawbacks, development of a hydrocarbon polymer electrolyte membrane that can replace Nafion (registered trademark) at low cost and excellent in membrane characteristics has recently been activated.

  In particular, several attempts have been made focusing on sulfonimide groups, which are highly acid-dissociable groups, in order to improve low-humidity proton conductivity. Patent Document 1 describes a polystyrene-based sulfonimide group-containing polymer. Patent Documents 2 and 3 and Non-Patent Document 1 propose an aromatic sulfonimide group-containing polymer.

JP2011-105948A JP 2008-163160 A US Patent Application Publication No. 2008/0286626

(Journal of Polymer Science: Part A: Polymer Chemistry, 44, 6007, 2006.)

  However, the present inventors have found that the prior art has the following problems. The polystyrene-based sulfonimide group-containing polymer described in Patent Document 1 is not only poor in chemical stability, particularly radical resistance, due to the presence of active hydrogen, but also because of an amorphous polymer having a relatively low glass transition temperature. The structure stability as an electrolyte membrane was lacking.

  Examples of using a poly (ether nitrile) -based polymer or a poly (ether sulfone) -based polymer in the main chain skeleton are disclosed in Patent Document 2 and Non-Patent Document 1 as sulfonimide group-containing polymers having higher chemical and structural stability. However, since an amorphous polymer having a high glass transition temperature is used for the basic skeleton, they are brittle and have poor physical durability. In addition, a further decrease in hot water resistance and physical durability due to the inclusion of many sulfonimide groups with high water absorption was cited as a problem.

Furthermore, Patent Document 3 describes a series of aromatic sulfonimide group-containing polymers having benzophenone having a sulfoneimide group having a terminal substituted with an aromatic group as a constituent unit. However, in these polymers, the terminal of the sulfonimide group is substituted with a hydrocarbon aromatic group having a low electron withdrawing property, so that the acid dissociation degree of the sulfonimide group is reduced and the ion exchange capacity due to the terminal aromatic group is reduced. The decline was considered as a further problem. Thus, the polymer electrolyte material in the prior art is insufficient as a means for improving economy, workability, proton conductivity, mechanical strength, chemical stability, and physical durability, and is industrially useful. It could not be a polymer electrolyte membrane.

In view of the background of such prior art, the present invention has excellent proton conductivity even under low humidification conditions and low temperature conditions, and is excellent in mechanical strength and fuel cutoff performance. Therefore, it is intended to provide a sulfonimide group-containing polymer and an aromatic sulfonimide derivative which can provide a polymer electrolyte material capable of achieving high output, high energy density, and long-term durability.

  The present invention employs the following means in order to solve such problems. That is, the aromatic sulfonimide derivative of the present invention is represented by the following general formula (M1).

(In Formula (M1), R ¹ and R ² each independently represent a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups. M ¹ and M ² represent a cation species selected from hydrogen, a metal cation, and an ammonium cation, and X ¹ and X ² represent a halogen atom.)
In addition, the sulfonimide group-containing polymer of the present invention is characterized by containing a structural unit represented by the following general formula (P1).

(In formula (P1), R ¹ and R ² each independently represents a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups. M ¹ , M ² each independently represents a cation species selected from hydrogen, a metal cation, and an ammonium cation.)
Furthermore, the polymer electrolyte material, the polymer electrolyte molded body, and the solid polymer fuel cell of the present invention include a sulfonimide group-containing polymer obtained by polymerization using such an aromatic sulfonimide derivative or the above general formula (P1). It is comprised using the sulfonimide group containing polymer containing the structural unit represented by these.

  According to the polymer having a sulfonimide group polymerized using the aromatic sulfonimide derivative of the present invention and the polymer electrolyte material comprising the sulfonimide group-containing polymer of the present invention, excellent proton conductivity and high performance under low humidification conditions. It is possible to achieve mechanical strength, high chemical stability, high output performance and excellent physical durability when used as a solid polymer fuel cell, and a polymer electrolyte molded body and solid polymer type using the same A fuel cell can be provided.

  Hereinafter, the present invention will be described in detail.

As a result of intensive studies aimed at overcoming the above-mentioned problems, the present invention results in an aromatic sulfonimide derivative having a highly acid-dissociable sulfonimide group in which the terminal is substituted with a highly electron-withdrawing perfluoroalkyl group, or a terminal. High-ion exchange capacity aromatic sulfonimide derivatives substituted with aromatic groups having an ionic group, sulfonimide group-containing polymers polymerized using them, and sulfonimide group-containing polymers having a specific structure are polymers. Chemical stability of electrolyte materials, especially fuel cell electrolyte membranes, including proton conductivity and power generation characteristics including low humidification conditions, processability such as film-forming properties, oxidation resistance, radical resistance, and hydrolysis resistance It has been clarified that it can exhibit excellent performance in physical durability such as mechanical strength and hot water resistance of the membrane, and can solve such problems all at once. .

That is, the aromatic sulfonimide derivative of the present invention is represented by the following general formula (M1).

(In formula (M1), R ¹ and R ² each independently represents a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups. M ¹ , M ² each independently represents a cation species selected from hydrogen, a metal cation, and an ammonium cation, and X ¹ and X ² represent a halogen atom.)
In the present invention, X ¹ and X ² represent halogen atoms such as fluorine, chlorine, bromine and iodine. Among them, fluorine and chlorine are more preferable and fluorine is most preferable from the viewpoint of reactivity.

R ¹ and R ² each independently represent a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups. Here, the perfluoroalkyl group refers to a substituent mainly composed of carbon and fluorine, and specifically refers to a substituent represented by C _n F _{2n + 1} and its oxygen and sulfur atom derivatives. . More specific examples include CF ₃ groups, C ₂ H ₅ groups, C ₃ H ₇ groups, C ₄ H ₉ groups, C ₅ H ₁₁ groups, C ₆ H ₁₃ groups, and the like. In addition, oxygen and sulfur atom derivatives of fluorinated hydrocarbon groups such as CF ₂ OCF ₃ group, C ₂ F ₄ OC ₂ F ₅ , CF ₂ SCF ₃ , C ₃ F ₆ SC ₃ F _{7 and the} like can be mentioned. It is not limited to examples. Among them, in terms of acid dissociation degree of sulfonimide _groups, preferably C _{n F 2n + 1} group, in terms of ease of synthesis, n is more preferably _C n _{F 2n + 1} group having from 1 to 20, in terms of ion exchange capacity C is more preferably a C _n F _{2n + 1} group in which n is 1 to 6, and most preferably a C _n F _{2n + 1} group in which n is 1 to 4. The aromatic group containing an ionic group is a hydrocarbon-based arylene group such as phenyl group, naphthyl group, biphenyl group, terphenyl group, phenalenyl group, pyrene group, fluorenyl group, pyridyl group, quinoxalyl group, thiophenyl group. Examples thereof include, but are not limited to, an ionic group-containing product of a heteroarylene group. Moreover, these aromatic groups may have arbitrary substituents other than an ionic group. Among them, an aromatic group having 4 to 20 carbon atoms is preferable in terms of ease of synthesis, an aromatic group having 4 to 12 carbon atoms is more preferable in terms of ion exchange capacity, and an aromatic group having 4 to 6 carbon atoms. Group groups are most preferred.

In the present invention, by replacing the terminal of the sulfonimide group with the perfluoroalkyl group, the acid-dissociation property of the sulfonimide group is increased due to the electron withdrawing property, and when the electrolyte material is used, a high low-humidity proton conductivity is obtained. Can be realized. On the other hand, when the terminal is substituted with an aromatic group having an ionic group, the acid-dissociation property of the sulfonimide group is slightly reduced because the electron withdrawing property is inferior to that of the perfluoroalkyl group. The introduced ionic group makes it possible to increase the ion exchange capacity, and when the electrolyte material is used, high low humidification proton conductivity can be realized. When the aromatic group does not contain an ionic group, the ion exchange capacity is lowered, and the low humidified proton conductivity when used as an electrolyte material is insufficient.

In the present invention, the ionic group used when R ¹ and / or R ² is an aromatic group is preferably a negatively charged atomic group, and preferably has a proton exchange ability. As such a functional group, a sulfonic acid group, a sulfonimide group, a sulfuric acid group, a phosphonic acid group, a phosphoric acid group, and a carboxylic acid group are preferably used. Here, the sulfonic acid group is a group represented by the following general formula (f1), the sulfonimide group is a group represented by the following general formula (f2) [in the general formula (f2), R represents an arbitrary organic group . The sulfuric acid group is represented by the following general formula (f3), the phosphonic acid group is represented by the following general formula (f4), and the phosphoric acid group is represented by the following general formula (f5) or (f6). And the carboxylic acid group means a group represented by the following general formula (f7).

Such ionic groups include cases where the functional groups (f1) to (f7) are salts. Examples of the cation forming the salt include an arbitrary metal cation, NR ⁴⁺ (R is an arbitrary organic group), and the like. In the case of a metal cation, the valence and the like are not particularly limited and can be used. Specific examples of preferable metal ions include Li, Na, K, Rh, Mg, Ca, Sr, Ti, Al, Fe, Pt, Rh, Ru, Ir, and Pd. Among these, as the block copolymer used in the present invention, Na, K, and Li that are inexpensive and can be easily proton-substituted are more preferably used.

Two or more kinds of these ionic groups can be contained in R ¹ and R ² , and can be appropriately selected depending on the balance of ion exchange capacity and acid dissociation degree. Among these, it is more preferable to have at least a sulfonic acid group and a sulfonimide group from the viewpoint of acid dissociation, and most preferable to have at least a sulfonic acid group from the viewpoint of raw material cost.

Here, the ion exchange capacity is the molar amount of the sulfonimide group introduced per unit dry weight of the block copolymer, the polymer electrolyte material, and the polymer electrolyte membrane. Indicates a high degree. The ion exchange capacity can be measured by elemental analysis, neutralization titration method or the like. It can also be calculated from the N / C ratio using elemental analysis, but it is difficult to measure when a nitrogen source other than the sulfonimide group is included. Therefore, in the present invention, the ion exchange capacity is defined as a value obtained by the neutralization titration method. The polymer electrolyte material of the present invention and the polymer electrolyte membrane also include an embodiment in which the sulfonimide-containing polymer of the present invention and other components are included, but in this case as well, the ion exchange capacity is the entire complex. It shall be obtained based on the quantity.

The measurement example of neutralization titration is as follows. The measurement is performed three times or more and the average value is taken.
(1) After wiping off the moisture on the membrane surface of the electrolyte membrane that has been proton-substituted and thoroughly washed with pure water,
Vacuum dry at 100 ° C for 12h or longer to obtain dry weight.
(2) Add 50 mL of 5 wt% sodium sulfate aqueous solution to the electrolyte, and leave it for 12 hours to exchange ions.
(3) The resulting sulfuric acid is titrated with 0.01 mol / L sodium hydroxide aqueous solution. A commercially available phenolphthalein solution for titration 0.1 w / v% is added as an indicator, and the point at which it becomes light reddish purple is the end point.
(4) The ion exchange capacity is determined by the following formula.

Ion exchange capacity (meq / g) =
[Concentration of sodium hydroxide aqueous solution (mmol / ml) × Drip amount (ml)] / Dry weight of sample (g)]
In the present invention, the preferred range of the ion exchange capacity of the aromatic sulfonimide derivative is that the terminal group is a perfluoroalkyl group or the aromatic group having an ionic group in terms of acid dissociation degree and water absorption. Distinguished by This is because as the acid dissociation degree increases, the hydrophilicity increases and the amount of water absorption increases. When the terminal group is a perfluoroalkyl group, it is preferably 1 to 4 meq / g, more preferably 1.2 meq / g or more, and still more preferably 1 from the balance of proton conductivity and water resistance when used as an electrolyte material. .6 meq / g or more, most preferably 2 meq / g or more. Moreover, 3.5 meq / g or less is more preferable, Most preferably, it is 3.2 meq / g or less. When the ion exchange capacity is less than 1 meq / g, proton conductivity may be insufficient, and when it is greater than 4 meq / g, water resistance may be insufficient. On the other hand, when the terminal group is an aromatic group having an ionic group, it is preferably 3.2 to 7 meq / g, more preferably 3.5 meq from the balance of proton conductivity and water resistance when used as an electrolyte material. / G or more, more preferably 4 meq / g or more, and most preferably 4.5 meq / g or more. Further, it is more preferably 6.2 meq / g or less, and most preferably 5 meq / g or less. When the ion exchange capacity is less than 3.2 meq / g, proton conductivity may be insufficient, and when it is greater than 7 meq / g, water resistance may be insufficient. The definition and measurement method of the ion exchange capacity are as described above.

In the present invention, M ¹ and M ² represent a cation species selected from hydrogen, a metal cation, and an ammonium cation. In the case of a metal cation, the valence and the like are not particularly limited and can be used. Specific examples of preferable metal ions include Li, Na, K, Rh, Mg, Ca, Sr, Ti, Al, Fe, Pt, Rh, Ru, Ir, and Pd. Among these, as the block copolymer used in the present invention, Na, K, and Li that are inexpensive and can be easily proton-substituted are more preferably used. Examples of ammonium cations include quaternary ammonium cations such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium, and tertiary ammonium cations generated by protonation of tertiary amines such as trimethylamine, triethylamine, and tributylamine. However, it can be used without being limited to these examples. The aromatic sulfonimide derivative of the present invention is excellent in chemical stability and physical stability due to the effect of electron withdrawing C = O group and the planarity of the benzophenone skeleton, and when it is a sulfonimide group-containing polymer. Furthermore, excellent proton conductivity can be realized even under low humidification conditions due to its high acid dissociation property and high ion exchange capacity.

As the aromatic sulfonimide derivative of the present invention, those represented by the following general formula (M2) are more preferable from the viewpoints of ease of synthesis, acid dissociability and ion exchange capacity.

(In Formula (M2), R ¹ and R ² each independently represent a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups. M ¹ M ² represents a cation species selected from hydrogen, a metal cation, and an ammonium cation, and X ¹ and X ² represent a halogen atom.)
Next, the sulfonimide group-containing polymer of the present invention will be described.

  The sulfonimide group-containing polymer of the present invention is characterized by being polymerized using the aromatic sulfonimide derivative represented by the general formula (M1). Moreover, although it became clear by superposing | polymerizing using the aromatic sulfonimide derivative represented by the said general formula (M1), it has not only that but a specific structure, It is characterized by the above-mentioned.

  Specific examples thereof include sulfonimide group-containing aromatic polyether ketones, sulfonimide group-containing aromatic polyether sulfones, sulfonimide group-containing aromatic polyether phosphine oxides, sulfonimide group-containing aromatic polysulfide ketones, Examples thereof include aromatic polymers such as sulfonimide group-containing aromatic polysulfide sulfones, sulfonimide group-containing aromatic polysulfide phosphine oxides, and sulfonimide group-containing polyarylenes.

  Among them, from the viewpoint of cost, there are sulfonimide group-containing aromatic polyether ketones, sulfonimide group-containing aromatic polyether sulfones, sulfonimide group-containing aromatic polyether phosphine oxides, and sulfonimide group-containing polyarylenes. More preferred, still more preferred are sulfonimide group-containing aromatic polyether ketones, sulfonimide group-containing aromatic polyether sulfones, and most preferred are sulfonimide group-containing aromatic polyether ketones.

  These sulfonimide group-containing aromatic polyethers can be synthesized by an aromatic nucleophilic substitution reaction between the aromatic sulfonimide derivative (dihalide compound) represented by the general formula (M1) and an arbitrary dihydric phenol compound. Is possible. The divalent phenol compound is not particularly limited, and can be appropriately selected in consideration of chemical stability, physical durability, cost, and the like. In addition, a monomer having a sulfonimide group introduced into these dihydric phenol compounds can be used as a monomer as long as the effect of the present invention is not adversely affected. However, in terms of reactivity, it does not have a sulfonimide group. Is more preferable. Specific examples of suitable divalent phenol compounds used in the present invention include divalent phenol compounds represented by the following general formulas (Y-1) to (Y-30). Divalent thiol compounds that are heteroatom derivatives of these divalent phenol compounds are also suitable examples. Among these, from the viewpoints of high electron density and high polymerization reactivity, divalent phenol compounds represented by general formulas (Y-1) to (Y-5) are more preferable, and (Y-1) is more preferable. ) To (Y-3).

  Moreover, as a bivalent phenol compound which has an electron withdrawing group and was excellent in chemical stability, following formula (Y-10)-(Y-11), (Y-13)-(Y-15) are shown. Can be mentioned. Of these, divalent phenol compounds represented by (Y-10), (Y-14), and (Y-15) are more preferable in terms of crystallinity and dimensional stability.

  Among the dihydric phenol compounds represented by the following general formulas (Y-1) to (Y-30), the dihydric phenol compound represented by the following general formula (Y-14) has chemical stability and physical properties. Most preferable in terms of stability.

(The divalent phenol compound represented by the general formulas (Y-1) to (Y-5) may be optionally substituted, but does not include a sulfonimide group.

(The divalent phenol compounds represented by the general formulas (Y-6) to (Y-9) may be optionally substituted, but n represents an integer of 1 or more.)

(The dihydric phenol compounds represented by the general formulas (Y-10) to (Y-19) may be optionally substituted, but n and m are integers of 1 or more, and Rp is an arbitrary organic group. Represents.)

(The dihydric phenol compounds represented by the general formulas (Y-20) to (Y-30) may be optionally substituted.)

For example, the structural unit obtained by the aromatic nucleophilic substitution reaction of the aromatic sulfonic acid derivative (dihalide compound) represented by the general formula (M1) and the divalent phenol compound represented by the general formula (Y-14) is It is represented by the following general formula (P1), and is a particularly preferred specific example as a constituent unit of the sulfonimide group-containing polymer of the present invention.

(In formula (P1), R ¹ and R ² each independently represents a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups. M ¹ M ² represents a cation species selected from hydrogen, a metal cation, and an ammonium cation.)
One of the preferable embodiments of the sulfonimide group-containing polymer in the present invention is a sulfonimide group-containing polymer having a structural unit represented by the general formula (P1). When the structural unit represented by the general formula (P1) is not included, it is not preferable because the hot water resistance, physical durability, and low humidified proton conductivity, which are the effects of the present invention, may not be compatible.
Furthermore, the content of the structural unit represented by the general formula (P1) in the sulfonimide group-containing polymer of the present invention is preferably 20% by weight or more. When the content of the structural unit represented by (P1) is less than 20% by weight, water resistance, physical durability and proton conductivity may not be compatible, which is not preferable. In the present invention, in order to obtain the sulfonic acid group-containing polymer represented by the general formula (P1), a protective group is introduced into the dihydric phenol compound, and after the polymerization or molding, the deprotection is performed. It is also preferable to convert to a structure represented by

  Examples of the protective group used in the sulfonimide group-containing polymer of the present invention include a protective group generally used in organic synthesis. The protective group is temporarily removed on the assumption that it is removed at a later stage. It is a substituent to be introduced, which protects a highly reactive functional group and renders it inert to the subsequent reaction, and can be deprotected after the reaction to return to the original functional group. . That is, it is a pair with a functional group to be protected. For example, a t-butyl group may be used as a protective group for a hydroxyl group, but when the same t-butyl group is introduced into an alkylene chain, It is not called a protecting group. The reaction for introducing a protecting group is called protection (reaction), and the reaction for removal is called deprotection (reaction).

  Such protection reactions include, for example, Theodora W. G reene, “Protective Groups in Organic Synthesis”, US, John Willy and Sands (John Wiley & Sons, Inc), 198 1, are described in detail, and these can be preferably used. It can be appropriately selected in consideration of the reactivity and yield of the protection reaction and deprotection reaction, the stability of the protecting group-containing state, the production cost, and the like. In addition, the stage for introducing a protecting group in the polymerization reaction may be selected from the monomer stage, the oligomer stage, or the polymer stage, and can be appropriately selected.

  Specific examples of the protection reaction include protecting / deprotecting the ketone moiety with an acetal or ketal moiety, and protecting / deprotecting the ketone moiety with a heteroatom analog of the acetal or ketal moiety, such as thioacetal or thioketal. The method of doing is mentioned. These methods are described in Chapter 4 of “Protective Groups in Organic Synthesis” (P rot e c t i v e G r o u ps i n O r g a n iC Snt h e s i s). However, it is not limited to these and can be preferably used. In terms of improving solubility in general solvents and reducing crystallinity, an aliphatic group, particularly an aliphatic group containing a cyclic moiety, is preferably used as a protective group in terms of large steric hindrance, and protects the ketone moiety. As the group, an acetal group and a ketal group are particularly preferably used.

  Preferred specific examples of the dihydric phenol compound having a protecting group include compounds represented by the following general formulas (r1) to (r10), and these dihydric phenol compounds from the viewpoint of reactivity and chemical stability. Derivatives can be mentioned.

Among these dihydric phenol compounds, the compounds represented by the general formulas (r4) to (r10) are more preferable from the viewpoint of stability, and more preferably the compounds represented by the general formulas (r4), (r5), and (r9). The compound represented by the general formula (r4) is most preferred.

Furthermore, the sulfonimide group-containing polymer of the present invention has a segment (A1) having a structural unit represented by the general formula (P1) and a segment (A2) having a structural unit not containing an ionic group. One of the more preferable embodiments is that the copolymerization mode is block copolymerization.

  In the present invention, the block copolymer represents a mode in which two or more different segments are copolymerized, and the segment is a partial structure in the block copolymer, and includes one type of repeating unit or a plurality of types of repeating units. It consists of a combination of repeating units and represents a molecular weight of 2000 or more. The sulfonimide group-containing polymer comprising the block copolymer of the present invention has a segment containing a sulfonimide group represented by the general formula (P1) and a segment not containing an ionic group. The phrase “segment not containing an ionic group” means that the segment may contain a small amount of an ionic group as long as the effect of the present invention is not adversely affected. Hereinafter, “does not contain an ionic group” may be used in the same meaning. The sulfonimide group-containing polymer comprising the block copolymer of the present invention comprises two or more types of mutually incompatible segment chains, that is, a hydrophilic segment containing a sulfonimide group and a hydrophobic segment containing no ionic group Are linked to form one polymer chain. In block copolymers, the short-chain interaction resulting from repulsion between chemically different segment chains causes phase separation into nano- or micro-domains consisting of each segment chain, and the segment chains are covalently bonded to each other. Each domain is arranged in a specific order by the effect of the long-range interaction resulting from. A higher-order structure created by combining domains composed of segment chains is called a nano- or micro-phase separation structure, and for ion conduction of a polymer electrolyte membrane, the spatial arrangement of ion-conducting segments in the membrane, that is, nano or The microphase separation structure becomes important. Here, the domain means a mass formed by aggregating similar segments in one or a plurality of polymer chains.

  Especially, it is more preferable that the sulfonimide group-containing polymer comprising the block copolymer of the present invention further contains one or more linker sites that connect the segments. Here, a linker is a site | part which connects between the segment (A1) containing a sulfonimide group, and the segment (A2) which does not contain an ionic group, Comprising: The segment (A1) containing a sulfonimide group And a segment having a different chemical structure from the segment (A2) not containing an ionic group. This linker enables the linkage between different segments while suppressing randomization, segment cleavage and side reactions due to the ether exchange reaction. Necessary for developing a phase separation structure. In the absence of a linker, segment cleavage such as randomization may occur, and the effects of the present invention may not be sufficiently obtained.

By appropriately selecting the chemical structure, segment chain length, molecular weight, ion exchange capacity, etc. of the sulfonimide group-containing polymer comprising the block copolymer of the present invention, the processability of the polymer electrolyte material, the domain size, the crystallinity / non- Various characteristics such as crystallinity, mechanical strength, proton conductivity, and dimensional stability can be controlled.

Next, a preferable specific example is given about the block copolymer of this invention. The block copolymer of the present invention exhibits a high proton conductivity under a wide range of humidity conditions as a polymer electrolyte material or a polymer electrolyte membrane because a hydrophilic segment containing a sulfonimide group forms a domain. In the case of the block copolymer containing a sulfonimide group of the present invention, the ion exchange capacity is preferably 0.1 to 5 meq / g, more preferably 1 meq / g or more, from the balance of proton conductivity and water resistance. Most preferably, it is 1.4 meq / g or more. Moreover, 3.5 meq / g or less is more preferable, Most preferably, it is 3 meq / g or less. When the ion exchange capacity is less than 0.1 meq / g, proton conductivity may be insufficient, and when it is greater than 5 meq / g, water resistance may be insufficient. The definition and measurement method of the ion exchange capacity are as described above.

  As the block copolymer of the present invention, the molar composition ratio (A1 / A2) of the segment (A1) containing a sulfonimide group and the segment (A2) containing no ionic group is 0.2 or more. Is more preferably 0.33 or more, and most preferably 0.5 or more. Moreover, 5 or less is more preferable, 3 or less is more preferable, and 2.5 or less is the most preferable. When the molar composition ratio A1 / A2 is less than 0.2 or exceeds 5, the effect of the present invention may be insufficient, proton conductivity under low humidification conditions may be insufficient, This is not preferable because physical durability may be insufficient. Here, the molar composition ratio (A1 / A2) represents the ratio of the number of moles of repeating units present in the segment (A1) to the number of moles of repeating units present in the segment (A2). In addition, for example, when the segment (A1) containing a sulfonimide group is composed of a structural unit (P1) containing a sulfonimide group, the molar calculation divides the number average molecular weight of the segment by the molecular weight of the corresponding structural unit (P1). However, the present invention is not limited to this example.

  The preferred range of the ion exchange capacity of the segment (A1) containing a sulfonimide group is that the terminal group is a perfluoroalkyl group and an ionic group in terms of acid dissociation and water absorption as described above. A distinction is made between aromatic groups. When the terminal group is a perfluoroalkyl group, it is preferably 1.2 meq / g or more, more preferably 1.5 meq / g or more, and most preferably 2 meq from the balance between proton conductivity and water resistance under low humidification. / G or more. Moreover, 3.5 meq / g or less is more preferable, Most preferably, it is 2.7 meq / g or less. When the ion exchange capacity is less than 1.2 meq / g, proton conductivity may be insufficient, and when it is greater than 3.5 meq / g, water resistance may be insufficient. On the other hand, when the terminal group is an aromatic group having an ionic group, it is preferably 2.2 meq or more, more preferably 3 meq / g or more from the balance between proton conductivity and water resistance under low humidification, Preferably it is 3.5 meq / g or more, most preferably 4 meq / g or more. Moreover, 6.2 meq / g or less is more preferable, Most preferably, it is 5.5 meq / g or less. When the ion exchange capacity is smaller than 2.2 meq / g, proton conductivity may be insufficient, and when it is larger than 6.2 meq / g, water resistance may be insufficient.

  The ion exchange capacity of the segment (A2) containing no ionic group is preferably low from the viewpoint of hot water resistance, mechanical strength, dimensional stability, and physical durability, more preferably 1 meq / g or less, and still more preferably 0.5 meq / g, most preferably 0.1 meq / g or less. When the ion exchange capacity of the segment (A2) not containing an ionic group exceeds 1 meq / g, the hot water resistance, mechanical strength, dimensional stability, and physical durability may be insufficient.

  As a segment that does not contain an ionic group, a structural unit that is chemically stable and exhibits crystallinity due to strong intermolecular cohesion is more preferable, and a block co-polymer with excellent mechanical strength, dimensional stability, and physical durability. Coalescence can be obtained.

  That is, in the present invention, it is particularly preferable that the structural unit not containing the ionic group is represented by the following general formula (P2).

(In the general formula (P2), Ar ^{1 to} Ar ⁴ represent an arbitrary divalent arylene group and may be optionally substituted, but do not contain an ionic group. Ar ^{1 to} Ar ⁴ are independent of each other. Two or more types of arylene groups may be used, and * represents a bonding site with the general formula (P2) or other structural unit.)
Here, preferable divalent arylene groups as Ar ^{1 to} Ar ⁸ are hydrocarbon arylene groups such as phenylene group, naphthylene group, biphenylene group, and fluorenediyl group, and heteroarylenes such as pyridinediyl, quinoxalinediyl, and thiophenediyl. Examples include, but are not limited to, groups. Ar ^{1 to} Ar ⁴ do not contain an ionic group and may be substituted with a group other than the ionic group, but the non-substituted one has proton conductivity, chemical stability, and physical durability. More preferable in terms. Furthermore, a phenylene group is preferable, and a p-phenylene group is most preferable. As a more preferable specific example of the structural unit represented by the general formula (P2) contained in the segment (A2) not containing an ionic group, a structure represented by the following general formula (O1) in terms of raw material availability Units are listed. Among these, from the viewpoint of mechanical strength due to crystallinity, dimensional stability, and physical durability, a structural unit represented by the following formula (P3) is more preferable. As content of the structural unit represented by general formula (P2) contained in the segment (A2) which does not contain an ionic group, the more one is preferable, 20 mol% or more is more preferable, 50 mol% or more is more preferable. More preferably, 80 mol% or more is most preferable. When the content is less than 20 mol%, the effects of the present invention on the mechanical strength, dimensional stability, and physical durability due to crystallinity may be insufficient, which is not preferable.

As the segment (A2) not containing an ionic group, a preferred example of a structural unit that is copolymerized in addition to the structural unit represented by the general formula (P2) is an aromatic polyether polymer containing a ketone group, that is, What has a structural unit shown by general formula (Q1), and does not contain an ionic group is mentioned.

(Z ¹ and Z ² in the general formula (Q1) each represent a divalent organic group containing an aromatic ring, and each of them may represent two or more groups, but does not include an ionic group. Each independently represents a positive integer.)
As preferred organic groups as Z ¹ and Z ² in the general formula (Q1), Z ¹ is a phenylene group, and Z ² is the following general formula (X-1), (X-2), (X-4) , (X-5) is more preferable. Moreover, although you may substitute by groups other than an ionic group, the direction where it is unsubstituted is more preferable at the point of crystallinity provision. Z ¹ and Z ² are more preferably a phenylene group, most preferably a p-phenylene group.

(The groups represented by the general formulas (X-1), (X-2), (X-4), and (X-5) may be optionally substituted with a group other than an ionic group). .

  Specific examples of the structural unit represented by the general formula (Q1) include the structural units represented by the following general formulas (Q2) to (Q7), but are not limited thereto. It is possible to select appropriately in consideration of crystallinity and mechanical strength. Among these, from the viewpoint of crystallinity and production cost, the structural unit represented by the general formula (Q1) is more preferably the following general formulas (Q2), (Q3), (Q6), and (Q7). Formulas (Q2) and (Q7) are most preferable.

(General formulas (Q2) to (Q7) are all represented in the para position, but may have other bonding positions such as ortho and meta positions as long as they have crystallinity. The para position is more preferable from the viewpoint of

As in the case of (P1), a protective group is introduced into the dihydric phenol compound in order to obtain a segment not containing the ionic group represented by the general formulas (P2), (Q1), and (P3) of the present invention. It is also preferable to deprotect after polymerization or molding and convert the structure to the structure represented by the general formula (P2), (Q1), or (P3). Preferred specific examples of the dihydric phenol compound having a protecting group include compounds represented by the above general formulas (r1) to (r10), and these dihydric phenol compounds from the viewpoint of reactivity and chemical stability. Derivatives can be mentioned. Among these dihydric phenol compounds, the compounds represented by the general formulas (r4) to (r10) are more preferable from the viewpoint of stability, and more preferably the compounds represented by the general formulas (r4), (r5), and (r9). The compound represented by the general formula (r4) is most preferred.

The number average molecular weight of the segment containing the sulfonimide group and the segment not containing the ionic group is related to the domain size of the phase separation structure. From the balance between proton conductivity and physical durability at low humidification, 0.5 More preferably, it is 10,000 or more and 50,000 or less, more preferably 10,000 or more and 40,000 or less, and most preferably 15,000 or more and 30,000 or less. The block copolymer of the present invention can observe a co-continuous or lamellar-like phase separation structure by transmission electron microscope observation by controlling the segment length ratio. By controlling the phase separation structure of the block copolymer, that is, the aggregation state and shape of segments containing sulfonimide groups and segments not containing ionic groups, excellent proton conductivity is achieved even under low humidification conditions. it can. The phase separation structure can be analyzed with a transmission electron microscope (TEM), an atomic force microscope (AFM), or the like.

  As the block copolymer of the present invention, when observed by TEM at 50,000 times, a phase separation structure is observed, and the average interlayer distance or average interparticle distance measured by image processing is 8 nm or more and 300 nm or less. Some are preferred. Among these, the average interlayer distance or the average interparticle distance is more preferably 10 nm or more and 100 nm or less, and most preferably 15 nm or more and 50 nm or less. When the phase separation structure is not observed by a transmission electron microscope, or when the average interlayer distance or the average interparticle distance is less than 8 nm, the continuity of the ion channel may be insufficient and the conductivity may be insufficient. Absent. Further, when the interlayer distance exceeds 5000 nm, the mechanical strength and dimensional stability may be deteriorated, which is not preferable.

  The method for forming the polymer electrolyte material of the present invention into a polymer electrolyte membrane is not particularly limited, but a method of forming a film from a solution state or a method of forming a film from a molten state is possible. In the former, for example, the polymer electrolyte material is dissolved in a solvent such as N-methyl-2-pyrrolidone, the solution is cast on a glass plate or the like, and the solvent is removed to form a film. It can be illustrated.

  The solvent used for film formation is not particularly limited as long as the polymer electrolyte material can be dissolved and then removed. For example, N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone , Dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, aprotic polar solvents such as hexamethylphosphontriamide, ester solvents such as γ-butyrolactone, butyl acetate, carbonates such as ethylene carbonate, propylene carbonate, etc. Solvent, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, alkylene glycol monoalkyl ether such as propylene glycol monoethyl ether, or isopropanol Alcohol solvents, water and mixtures thereof is preferably used, is preferred for high highest solubility aprotic polar solvent. It is also preferable to add a crown ether such as 18-crown-6 in order to enhance the solubility of the segment containing a sulfonimide group.

  In the present invention, when a block copolymer is used, the selection of the solvent is important for the phase separation structure, and it is also preferable to use a mixture of an aprotic polar solvent and a low polarity solvent. It is a simple method.

It is a preferable method to obtain a tough membrane by subjecting the polymer solution prepared to a required solid content concentration to normal pressure filtration or pressure filtration to remove foreign substances present in the polymer electrolyte solution. The filter medium used here is not particularly limited, but a glass filter or a metallic filter is suitable. In the filtration, the pore size of the minimum filter through which the polymer solution passes is preferably 1 μm or less. If filtration is not carried out, foreign matter is allowed to enter, and film breakage occurs or durability becomes insufficient.

Next, the obtained polymer electrolyte membrane is preferably heat-treated in the state of metal or ammonium salt at least part of the sulfonimide group. If the polymer electrolyte material to be used is polymerized in a salt state at the time of polymerization, it is preferable to perform film formation and heat treatment as it is. The metal cation of the metal salt only needs to be capable of forming a salt with sulfonimide, but from the viewpoint of cost and environmental load, Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ti, V , Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, W, and the like are preferable. Among these, Li, Na, K, Ca, Sr, Ba cations are more preferable, and Li, Na, and K cations are more preferable. Cations are more preferred. From the same viewpoint, the ammonium cation of the ammonium salt includes tertiary ammonium such as trimethylammonium, triethylammonium, tripropylammonium and tributylammonium, or tetramethylammonium, tetraethylammonium, tetrapropylammonium and tetrabutylammonium. Quaternary ammonium cations are preferred. The temperature of this heat treatment is preferably 80 to 350 ° C, more preferably 100 to 200 ° C, and particularly preferably 120 to 150 ° C. The heat treatment time is preferably 10 seconds to 12 hours, more preferably 30 seconds to 6 hours, and particularly preferably 1 minute to 1 hour. If the heat treatment temperature is too low, mechanical strength and physical durability may be insufficient. On the other hand, if it is too high, chemical decomposition of the film material may proceed. If the heat treatment time is less than 10 seconds, the heat treatment effect is insufficient. On the other hand, when it exceeds 12 hours, the film material tends to deteriorate. The polymer electrolyte membrane obtained by the heat treatment can be proton-substituted by being immersed in an acidic aqueous solution as necessary. By forming by this method, the polymer electrolyte membrane of the present invention can achieve both a good balance between proton conductivity and physical durability.

  The sulfonimide group-containing polymer of the present invention is suitable as a polymer electrolyte material, and particularly preferably used as a polymer electrolyte molded body. In the present invention, the polymer electrolyte molded body means a molded body containing the polymer electrolyte material of the present invention. The polymer electrolyte molded body of the present invention includes membranes (including films and films), plates, fibers, hollow fibers, particles, lumps, micropores, coatings, and foams. It can take various forms depending on the intended use. The polymer can be applied to a wide range of applications because it can improve the design freedom of the polymer and improve various properties such as mechanical properties and solvent resistance. It is particularly suitable when the polymer electrolyte molded body is a membrane.

  In the present invention, the method for deprotecting at least a part of the ketone moiety protected with an acetal and / or ketal group to form a ketone moiety is not particularly limited. The deprotection reaction can be carried out in the presence of water and acid under non-uniform or uniform conditions, but from the viewpoint of mechanical strength and solvent resistance, it is acid-treated after being formed into a film or the like. The method is more preferred. Specifically, it is possible to deprotect the molded membrane by immersing it in an aqueous sulfuric acid solution, and the acid concentration and the aqueous solution temperature can be appropriately selected.

  The weight ratio of the acidic aqueous solution required for the polymer is preferably 1 to 100 times, but a larger amount of water can be used. The acid catalyst is preferably used at a concentration of 0.1 to 50% by weight of water present. Suitable acid catalysts include strong mineral acids such as hydrochloric acid, nitric acid, fluorosulfonic acid, sulfuric acid, and strong organic acids such as p-toluenesulfonic acid, trifluoromethane sulfonic acid, and the like. Depending on the film thickness of the polymer and the like, the amount of acid catalyst and excess water, reaction pressure, and the like can be selected as appropriate.

  For example, in the case of a film having a thickness of 50 μm, almost all of the film can be easily deprotected by dipping in an acidic aqueous solution as exemplified by a 6N hydrochloric acid aqueous solution and heating at 95 ° C. for 1 to 48 hours. It is. Further, even when immersed in a 1N aqueous hydrochloric acid solution at 25 ° C. for 24 hours, most of the protecting groups can be deprotected. However, the deprotection conditions are not limited to these, and the deprotection may be performed with an acid gas, an organic acid, or the like, or may be deprotected by heat treatment.

  When the polymer electrolyte material of the present invention is used for a polymer electrolyte fuel cell, a polymer electrolyte membrane and an electrode catalyst layer are suitable. Among them, it is preferably used for a polymer electrolyte membrane. This is because when used for a polymer electrolyte fuel cell, it is usually used as a polymer electrolyte membrane or an electrode catalyst layer binder in the form of a membrane.

  The molded polymer electrolyte of the present invention can be applied to various uses. For example, extracorporeal circulation column, medical use such as artificial skin, filtration use, ion exchange resin use such as chlorine-resistant reverse osmosis membrane, various structural materials use, electrochemical use, humidification membrane, anti-fogging membrane, antistatic membrane, Applicable to solar cell membranes and gas barrier materials. It is also suitable as an artificial muscle and actuator material. Among these, it can be preferably used for various electrochemical applications. Examples of the electrochemical application include a fuel cell, a redox flow battery, a water electrolysis device, a chloroalkali electrolysis device, and the like, among which the fuel cell is most preferable.

  The thickness of the polymer electrolyte membrane obtained by the present invention is preferably 1 to 2000 μm. In order to obtain the mechanical strength and physical durability of the membrane that can withstand practical use, it is more preferably thicker than 1 μm, and in order to reduce membrane resistance, that is, improve power generation performance, it is preferably thinner than 2000 μm. A more preferable range of the film thickness is 3 to 50 μm, and a particularly preferable range is 10 to 30 μm. The film thickness can be controlled by the solution concentration or the coating thickness on the substrate.

  In addition, the polymer electrolyte membrane obtained by the present invention contains additives such as crystallization nucleating agents, plasticizers, stabilizers, antioxidants or mold release agents used in ordinary polymer compounds. It can be added within a range not contrary to the purpose.

  In addition, the polymer electrolyte membrane obtained by the present invention has various polymers, elastomers, and the like for the purpose of improving mechanical strength, thermal stability, workability, etc. within a range that does not adversely affect the above-mentioned various properties. Fillers, fine particles, various additives, and the like may be included. Moreover, you may reinforce with a microporous film, a nonwoven fabric, a mesh, etc.

  A polymer electrolyte fuel cell has a structure in which a hydrogen ion conductive polymer electrolyte membrane is used as an electrolyte membrane, and a catalyst layer, an electrode base material, and a separator are sequentially laminated on both sides thereof. Of these, the catalyst layer laminated on both sides of the electrolyte membrane (that is, the catalyst layer / electrolyte membrane / catalyst layer configuration) is called an electrolyte membrane with a catalyst layer (CCM), and further on both sides of the electrolyte membrane. A catalyst layer and a gas diffusion substrate laminated in sequence (that is, a gas diffusion substrate / catalyst layer / electrolyte membrane / catalyst layer / gas diffusion substrate layer structure) are electrode-electrolyte membrane assemblies or membranes. It is called an electrode assembly (MEA).

  As a manufacturing method of this electrolyte membrane with a catalyst layer, the coating system of apply | coating and drying the catalyst layer paste composition for forming a catalyst layer on the electrolyte membrane surface is generally performed. However, with this coating method, the electrolytic membrane is swollen and deformed by a solvent such as water or alcohol contained in the paste, and there is a problem that it is difficult to form a desired catalyst layer on the electrolyte membrane surface. Moreover, since the electrolytic membrane is also exposed to a high temperature in the drying step, there is a problem that the electrolytic membrane undergoes thermal expansion or the like and is deformed. In order to overcome this problem, there has been proposed a method (transfer method) in which only a catalyst layer is prepared on a substrate in advance and the catalyst layer is transferred to laminate the catalyst layer on the electrolyte membrane (for example, transfer method). JP 2009-9910).

Since the polymer electrolyte membrane obtained by the present invention is tough and excellent in solvent resistance due to crystallinity, it is particularly suitable for use as an electrolyte membrane with a catalyst layer in any of the above coating methods and transfer methods. it can.

  When the MEA is produced by a hot press, there is no particular limitation, and a known method (for example, a chemical plating method described in Electrochemistry, 1985, 53, p.269, edited by the Electrochemical Society (J. Electrochem. Soc. , Electrochemical Science and Technology, 1988, 135, 9, p.2209., Gas diffusion electrode hot press bonding method, etc.) can be applied.

  In the case of integration by heating press, the temperature and pressure may be appropriately selected depending on the thickness of the electrolyte membrane, the moisture content, the catalyst layer, and the electrode substrate. Further, in the present invention, it is possible to form a composite by pressing even when the electrolyte membrane is in a dry state or in a state of absorbing water. Specific press methods include a roll press that defines pressure and clearance, and a flat plate press that defines pressure. From the viewpoint of industrial productivity and suppression of thermal decomposition of a polymer material having a sulfonic acid group, the press method is 0. It is preferable to carry out in the range of from ℃ to 250 ℃. The pressurization is preferably as weak as possible from the viewpoint of electrolyte membrane and electrode protection. In the case of a flat plate press, a pressure of 10 MPa or less is preferable, and the electrode and the electrolyte membrane are stacked without carrying out the complexing by the hot press process. Cell formation is also one of the preferred options from the viewpoint of preventing short-circuiting of the anode and cathode electrodes. In the case of this method, when power generation is repeated as a fuel cell, the deterioration of the electrolyte membrane presumed to be caused by a short-circuited portion tends to be suppressed, and the durability as a fuel cell is improved.

  Furthermore, the application of the solid polymer fuel cell using the polymer electrolyte material and the polymer electrolyte membrane of the present invention is not particularly limited, but a power supply source for a mobile body is preferable. In particular, mobile devices such as mobile phones, personal computers, PDAs, televisions, radios, music players, game machines, headsets, DVD players, human-type and animal-type robots for industrial use, home appliances such as cordless vacuum cleaners, and toys , Electric bicycles, motorcycles, automobiles, buses, trucks and other vehicles and ships, power supplies for mobiles such as railways, stationary primary generators such as stationary generators, or alternatives to these It is preferably used as a hybrid power source.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these. In addition, the measurement conditions of each physical property are as follows.

(1) Measured by ion exchange capacity neutralization titration method. The measurement was performed 3 times and the average value was taken.
1. Moisture on the membrane surface of the electrolyte membrane which had been subjected to proton substitution and was thoroughly washed was wiped off and then vacuum-dried at 100 ° C. for 12 hours or more to obtain a dry weight.
2. 50 mL of 5 wt% sodium sulfate aqueous solution was added to the electrolyte, and ion exchange was performed by allowing to stand for 12 hours.
3. The generated sulfuric acid was titrated with 0.01 mol / L sodium hydroxide aqueous solution. A commercially available phenolphthalein solution for titration (0.1 w / v%) was added as an indicator, and the point at which it turned light reddish purple was used as the end point.
4). The ion exchange capacity was determined by the following formula.
Ion exchange capacity (meq / g) = [concentration of sodium hydroxide aqueous solution (mmol / ml) × drop amount (ml)] / dry weight of sample (g)
(2) Proton conductivity After immersing the membrane-like sample in pure water at 25 ° C. for 24 hours, it is placed in a constant temperature and humidity chamber, and proton conduction is conducted in the range of 80 ° C. and relative humidity 95% by the constant potential AC impedance method. The humidity dependence of the degree was measured.

  As a measuring apparatus, a Solartron electrochemical measurement system (Solartron 1287 Electrochemical Interface and Solartron 1255B Frequency Response Analyzer) was used, and constant potential impedance measurement was performed by a two-terminal method to determine proton conductivity. The AC amplitude was 50 mV. A sample having a width of 10 mm and a length of 50 mm was used. The measurement jig was made of phenol resin, and the measurement part was opened. As an electrode, a platinum plate (thickness: 100 μm, 2) was used. The electrodes were disposed at a distance of 15 mm between the electrodes, on the front side and the back side of the sample film so as to be parallel to each other and orthogonal to the longitudinal direction of the sample film.

(3) Number average molecular weight, weight average molecular weight The number average molecular weight and the weight average molecular weight of the polymer were measured by GPC. Tosoh's HLC-8022GPC is used as an integrated device of an ultraviolet detector and a differential refractometer, and Tosoh's TSK gel SuperHM-H (inner diameter 6.0 mm, length 15 cm) is used as the GPC column. N-methyl-2 -Measured with a pyrrolidone solvent (N-methyl-2-pyrrolidone solvent containing 10 mmol / L lithium bromide) at a sample concentration of 0.1 wt%, a flow rate of 0.2 mL / min, and a temperature of 40 ° C. The number average molecular weight and the weight average molecular weight were determined.

(4) Film thickness It measured using Mitutoyo ID-C112 type | mold set to Mitutoyo granite comparator stand BSG-20.

(5) Purity analysis of bisphenol compound Quantitative analysis was performed by gas chromatography (GC) under the following conditions.
Column: DB-5 (manufactured by J & W) L = 30m Φ = 0.53mm D = 1.50μm
Carrier: Helium (Linear velocity = 35.0 cm / sec)
Analysis conditions Inj. temp. 300 ° C
Dect. temp. 320 ° C
Oven 50 ° C x 1 min
Rate 10 ℃ / min
Final 300 ℃ × 15min
SP ratio 50: 1
(6) Nuclear magnetic resonance spectrum (NMR)
NMR measurement was performed under the following measurement conditions, and the structure of the aromatic sulfonic acid derivative was confirmed.
Device: EX-270
Resonance frequency: 270 MHz (1H-NMR)
Measurement temperature: Room temperature Solvent: DMSO-d6
Internal reference material: TMS (0 ppm)
Number of integrations: 16 times (7) Hot water resistance The hot water resistance of the electrolyte membrane was evaluated by measuring the dimensional change rate in hot water at 95 ° C. The electrolyte membrane was cut into a strip having a length of about 5 cm and a width of about 1 cm, immersed in water at 25 ° C. for 24 hours, and the length (L1) was measured with a caliper. The electrolyte membrane was immersed in hot water at 95 ° C. for 8 hours, and then the length (L2) was measured again with a caliper, and the size change was visually observed.

(8) Observation of phase separation structure by transmission electron microscope (TEM) A sample piece was immersed in a 2 wt% lead acetate aqueous solution as a staining agent and left at 25 ° C. for 48 hours. A dyed sample was taken out, embedded in a visible curable resin, and fixed by irradiation with visible light for 30 seconds.

  A 100 nm flake was cut at room temperature using an ultramicrotome, and the obtained flake was collected on a Cu grid and used for TEM observation. Observation was carried out at an acceleration voltage of 100 kV, and photography was carried out so that the photographic magnification was × 8,000, × 20,000, and × 100,000. As a device, TEM H7100FA (manufactured by Hitachi, Ltd.) was used.

Synthesis example 1
Synthesis of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane (K-DHBP) represented by the following formula (G1)

  A 500 ml flask equipped with a stirrer, thermometer and distillation tube was charged with 49.5 g of 4,4'-dihydroxybenzophenone, 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate and 0.50 g of p-toluenesulfonic acid monohydrate. did. Thereafter, the mixture was stirred while maintaining at 78 to 82 ° C. for 2 hours. Further, the internal temperature was gradually raised to 120 ° C. and heated until the distillation of methyl formate, methanol, and trimethyl orthoformate completely stopped. After cooling this reaction liquid to room temperature, the reaction liquid was diluted with ethyl acetate, the organic layer was washed with 100 ml of 5% aqueous potassium carbonate solution and separated, and then the solvent was distilled off. Crystals were precipitated by adding 80 ml of dichloromethane to the residue, filtered and dried to obtain 52.0 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane. GC analysis of the crystals revealed 99.8% 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane and 0.2% 4,4'-dihydroxybenzophenone.

Synthesis example 2
Synthesis of disodium-3,3′-disulfonate-4,4′-difluorobenzophenone represented by the following formula (G2)

109.1 g (Aldrich reagent) of 4,4′-difluorobenzophenone was reacted at 100 ° C. for 10 hours in 150 mL of fuming sulfuric acid (50% SO ₃ ) (Wako Pure Chemicals reagent). Thereafter, the mixture was poured little by little into a large amount of water, neutralized with NaOH, and 200 g of sodium chloride was added to precipitate the composite. The resulting precipitate was filtered off and recrystallized with an aqueous ethanol solution to obtain disodium 3,3′-disulfonate-4,4′-difluorobenzophenone represented by the above general formula (G2). The purity was 99.3%. The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

Example 1
(Synthesis of an aromatic sulfonimide derivative represented by the following formula (G3))

In a 1 L flask equipped with a stirrer, 133 g of 3,3′-disulfonate-4,4′-difluorobenzophenone was weighed in a nitrogen stream, dissolved in 330 mL of acetonitrile and 250 mL of sulfolane, and further added 290 g of phosphoryl trichloride. After heating at reflux for 20 hours, 20 mL of N, N-dimethylacetamide was added and the mixture was heated to reflux for 16 hours. After cooling with ice, 1.5 L of cold water was added, and the resulting precipitate was collected by filtration and washed with 500 mL of cold water. The precipitate was dried at room temperature under reduced pressure and recrystallized with toluene at 300 mL to obtain 65 g of 5,5′-carbonylbis (2-fluorobenzene-1-sulfonyl chloride). The structure was confirmed by ¹ H-NMR.

A solution of 33.2 g of 5,5′-carbonylbis (2-fluorobenzene-1-sulfonyl chloride) and 26.6 g of trifluoromethanesulfonamide in 250 mL of dehydrated acetone and ice-cooled, 54 mL of triethylamine was added dropwise under nitrogen. The reaction mixture was stirred at room temperature for 24 hours. After the triethylammonium chloride precipitate was separated by filtration, the filtrate was concentrated on a rotary evaporator, diluted with 400 mL of ethyl acetate and washed twice with 200 mL of 1N HCl. The organic phase was dried over sodium sulfate and the solvent removed to give the acidic sulfonimide crude product as a reddish brown viscous liquid. The product was redissolved in methanol / water (200/75 mL) and treated with 13.82 g K2CO3 dissolved in 14 ml water. The solution was filtered off, concentrated to about 100 mL and gradually cooled. The precipitate was collected by filtration, washed with water, dried, and recrystallized with ethanol to obtain 44.13 g of sulfonimide potassium salt (G3). The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

  Example 2 (Synthesis of an aromatic sulfonimide derivative represented by the following formula (G4))

In a SUS autoclave, 30 g of 5,5′-carbonylbis (2-fluorobenzene-1-sulfonyl chloride) synthesized in Example 1 was dissolved in 250 mL of dehydrated acetone, cooled to −40 ° C., and anhydrous ammonia. After adding 45 g, the temperature was raised to 20 ° C. and stirred for 3 hours. The product was collected by filtration to obtain a sulfonamide compound. Subsequently, 26 g of the sulfonamide and 38 g of benzene-1,3-disulfonyl dichloride were dissolved in 220 mL of dehydrated acetone and cooled with ice. Then, 14 g of triethylamine was slowly added dropwise under nitrogen, and the reaction mixture was stirred at room temperature for 24 hours. After the triethylammonium chloride precipitate was separated by filtration, the filtrate was concentrated by rotary evaporator, diluted with 350 mL of ethyl acetate and washed twice with 175 mL of 1N HCl. The organic phase was dried over sodium sulfate and the solvent was removed to give a crude acidic sulfonimide product. The product was redissolved in methanol / water (170/65 mL) and treated with 24 g K2CO3 dissolved in 12 ml water. The solution was filtered off, concentrated to about 100 mL and gradually cooled. The precipitate was collected by filtration, washed with water, dried, and purified by recrystallization with ethanol to obtain sulfonimide potassium salt (G4). The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

  Example 3 (Synthesis of an aromatic sulfonimide derivative represented by the following formula (G5))

In a 1 L flask equipped with a stirrer, under a nitrogen stream, 100 g of the sulfonimide derivative (G4) synthesized in Example 2 was weighed with 133 g of 3,3′-disulfonate-4,4′-difluorobenzophenone and acetonitrile. It was dissolved in 110 mL and 90 mL of sulfolane, 100 g of phosphoryl trichloride was further added, and the mixture was heated to reflux for 2 hours. Then, 7 mL of N, N-dimethylacetamide was added, and the mixture was heated to reflux for 16 hours. After cooling with ice, 1.5 L of cold water was added, and the resulting precipitate was collected by filtration and washed with 500 mL of cold water. The precipitate was dried under reduced pressure at room temperature and recrystallized with toluene at 300 mL to obtain 82 g of a sulfonic acid chloride. The structure was confirmed by ¹ H-NMR.
Subsequently, 70 g of the sulfonic acid chloride and 25 g of trifluoromethanesulfonamide were dissolved in 240 mL of dehydrated acetone and ice-cooled. Then, 51 mL of triethylamine was added dropwise under nitrogen, and the reaction mixture was stirred at room temperature for 24 hours. After the triethylammonium chloride precipitate was separated by filtration, the filtrate was concentrated by rotary evaporator, diluted with 380 mL of ethyl acetate and washed twice with 190 mL of 1N HCl. The organic phase was dried over sodium sulfate and the solvent was removed to give a crude acidic sulfonimide product. The product was redissolved in methanol / water (190/70 mL) and treated with 13.1 g K2CO3 dissolved in 13 ml water. The solution was filtered off, concentrated to about 100 mL and gradually cooled. The precipitate was collected by filtration, washed with water, dried, and purified by recrystallization with ethanol to obtain sulfonimide potassium salt (G5). The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

  Example 4 (Synthesis of an aromatic sulfonimide derivative represented by the following formula (G6))

A sulfonimide potassium salt (G6) was obtained in the same manner as described in Example 2, except that benzene-1,3-disulfonyl dichloride was changed to 48.5 g of biphenyl-2,4-disulfonyl dichloride. The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

  Example 5 (Synthesis of an aromatic sulfonimide derivative represented by the following formula (G7))

A sulfonimide potassium salt (G7) was obtained in the same manner as described in Example 1, except that trifluoromethanesulfonamide was changed to 89 g of heptadecafluorooctanesulfonamide. The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

Example 6
(Sulfonimide group-containing polymer represented by the following general formula (G8))

  In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 28.0 g of potassium carbonate (Aldrich reagent, 202 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and the above example Sulfonimide potassium salt (G3) 60.2 g (84 mmol), 4,4′-difluorobenzophenone 4,45 g (Aldrich reagent, 20.4 mmol) and 18-crown-6 19.5 g (Wako Pure) 74 mmol) was added, and after nitrogen substitution, dehydration was performed at 180 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, and then the temperature was raised to remove toluene, and polymerization was performed at 210 ° C. for 3 hours. Purification was performed by reprecipitation in a large amount of isopropyl alcohol to obtain a precursor polymer having a ketal group. The weight average molecular weight was 330,000.

  A 25 wt% N-methylpyrrolidone (NMP) solution in which the obtained precursor polymer was dissolved was subjected to pressure filtration using a glass fiber filter, cast onto a glass substrate, dried at 100 ° C. for 4 h, Heat treatment was performed at 150 ° C. for 10 minutes under nitrogen to obtain a polyketal ketone film (film thickness: 24 μm). The solubility of the polymer was very good. After immersing in a 10% by weight sulfuric acid aqueous solution at 95 ° C. for 24 hours to carry out proton substitution and deprotection reaction, immersing in a large excess amount of pure water for 24 hours and washing thoroughly, the sulfonimide represented by the above formula (G4) A polymer electrolyte membrane made of a group-containing polymer was obtained. The resulting membrane had a sulfonimide group density of 2.1 meq / g.

It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 290 mS / cm at 80 ° C. and 85% relative humidity, and 2 mS / cm at 80 ° C. and 25% relative humidity, and was excellent in low humidified proton conductivity. Further, the dimensional change rate was relatively small at 13%, and the hot water resistance was also excellent. In addition, the presence of a ketal group was not observed in NMR.

Example 7
(Sulfonimide group-containing polymer represented by the following general formula (G9))

  In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 24.5 g of potassium carbonate (Aldrich reagent, 177 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and the above example Sulfonimide potassium salt (G3) obtained in 1 (43.9 g, 61.2 mmol), 4,4′-difluorobenzophenone 8.73 g (Aldrich reagent, 40 mmol) and 18-crown-6, 14.2 g (Wako Pure) The drug was charged with 33.9 mmol), purged with nitrogen, dehydrated at 180 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, heated to remove toluene, and polymerized at 210 ° C. for 3 hours. Purification was performed by reprecipitation in a large amount of isopropyl alcohol to obtain a precursor polymer having a ketal group. The weight average molecular weight was 300,000.

  The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing polymer represented by the above formula (G5). The resulting membrane had a sulfonimide group density of 1.8 meq / g.

  It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 240 mS / cm at 80 ° C. and 85% relative humidity, and 1 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent in low humidification proton conductivity. Further, the dimensional change rate was relatively small at 10%, and the hot water resistance was also excellent. In addition, the presence of a ketal group was not observed in NMR.

Example 8

(Sulfonimide group-containing polymer represented by the following general formula (G10))

  A precursor having a ketal group in the same manner as in Example 7 except that 25.8 g (100 mmol) of KDHBP was changed to 12.9 g (50 mmol) of K-DHBP and 9.31 g (50 mmol) of 4,4′-biphenol. A body polymer was obtained. The weight average molecular weight was 260,000.

  The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing polymer represented by the above formula (G9). The resulting membrane had a sulfonimide group density of 1.7 meq / g.

  It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 210 mS / cm at 80 ° C. and 85% relative humidity, and 0.7 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent in low humidification proton conductivity. Further, the dimensional change rate was relatively small at 18%, and the hot water resistance was also excellent. In addition, the presence of a ketal group was not observed in NMR.

Example 9

(Sulfonimide group-containing polymer represented by the following general formula (G11))

(In the formula, * represents a binding site with another site)
A precursor having a ketal group in the same manner as in Example 7 except that 25.8 g (100 mmol) of KDHBP was changed to 18.1 g (70 mmol) of K-DHBP and 4.81 g (30 mmol) of 2,6-dihydroxynaphthalene. A body polymer was obtained. The weight average molecular weight was 280,000.

  The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing polymer represented by the above formula (G11). The resulting membrane had a sulfonimide group density of 1.7 meq / g.

  It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. Proton conductivity was 220 mS / cm at 80 ° C. and 85% relative humidity, and 0.8 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent. Further, the dimensional change rate was relatively small at 16%, and the hot water resistance was excellent. In addition, the presence of a ketal group was not observed in NMR.

Example 10

(Sulfonimide group-containing polymer represented by the following general formula (G12))

(In the formula, * represents a binding site with another site)
The same method as in Example 7 except that 43.9 g (61.2 mmol) of the sulfonimide potassium salt (G3) was changed to 64.8 g (61.2 mmol) of the sulfonimide potassium salt (G4) obtained in Example 2. A precursor polymer having a ketal group was obtained. The weight average molecular weight was 320,000.

  The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing polymer represented by the above formula (G12). The resulting membrane had a sulfonimide group density of 3 meq / g.

  It was a tough electrolyte membrane, and was a transparent and uniform membrane visually. The proton conductivity was 600 mS / cm at 80 ° C. and 85% relative humidity, and 8 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent in low humidification proton conductivity. The dimensional change rate was 28%, which was relatively small. In addition, the presence of a ketal group was not observed in NMR.

Example 11

(Sulfonimide group-containing polymer represented by the following general formula (G13))

(In the formula, * represents a binding site with another site)
The same method as in Example 7 except that 43.9 g (61.2 mmol) of the sulfonimide potassium salt (G3) was changed to 75.4 g (61.2 mmol) of the sulfonimide potassium salt (G5) obtained in Example 3. A precursor polymer having a ketal group was obtained. The weight average molecular weight was 310,000.

  The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing polymer represented by the above formula (G13). The resulting membrane had a sulfonimide group density of 2.6 meq / g.

  It was a tough electrolyte membrane, and was a transparent and uniform membrane visually. The proton conductivity was 630 mS / cm at 80 ° C. and 85% relative humidity, and 8.2 mS / cm at 80 ° C. and 25% relative humidity, and was excellent in low humidified proton conductivity. Moreover, the dimensional change rate was relatively small at 35%. In addition, the presence of a ketal group was not observed in NMR.

Example 12

(Sulfonimide group-containing polymer represented by the following general formula (G14))

(In the formula, * represents a binding site with another site)
The same method as in Example 7 except that 43.9 g (61.2 mmol) of the sulfonimide potassium salt (G3) was changed to 65.7 g (61.2 mmol) of the sulfonimide potassium salt (G6) obtained in Example 4. A precursor polymer having a ketal group was obtained. The weight average molecular weight was 320,000.

  The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing polymer represented by the above formula (G14). The sulfonimide group density of the obtained membrane was 2.8 meq / g.

  It was a tough electrolyte membrane, and was a transparent and uniform membrane visually. The proton conductivity was 570 mS / cm at 80 ° C. and 85% relative humidity, and 6.5 mS / cm at 80 ° C. and 25% relative humidity, and was excellent in low humidified proton conductivity. The dimensional change rate was 26%, which was relatively small. In addition, the presence of a ketal group was not observed in NMR.

Example 13

(Sulfonimide group-containing polymer represented by the following general formula (G15))

  In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 40.5 g of potassium carbonate (Aldrich reagent, 293 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and the above example 143 g (101 mmol) of sulfonimide potassium salt obtained in 5 and 18-crown-6 and 23.5 g (89.1 mmol of Wako Pure Chemical Industries) were added, and after nitrogen substitution, 300 mL of N-methylpyrrolidone (NMP), toluene After dehydration in 100 mL at 180 ° C., the temperature was raised to remove toluene, and polymerization was carried out at 210 ° C. for 3 hours. Purification was performed by reprecipitation in a large amount of isopropyl alcohol to obtain a precursor polymer having a ketal group. The weight average molecular weight was 280,000.

  The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing polymer represented by the above formula (G15). The resulting membrane had a sulfonimide group density of 1.3 meq / g.

It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 190 mS / cm at 80 ° C. and a relative humidity of 85%, and 0.7 mS / cm at 80 ° C. and a relative humidity of 25%, which was excellent in low humidification proton conductivity for a low ion exchange capacity. . It is thought that proton dissociation and proton conductivity were improved by substituting the end of the sulfonimide group with a perfluoroalkyl group. Further, the dimensional change rate was as small as 5%, and the hot water resistance was also excellent. In addition, the presence of a ketal group was not observed in NMR. Example 14
(Polymerization of prepolymer represented by the following general formula (G16))

(G16)


In a 500 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 13.82 g of potassium carbonate (Aldrich reagent, 100 mmol), 20.66 g (80 mmol) of K-DHBP obtained in Synthesis Example 1 and 4,4 17.46 g (Aldrich reagent, 80 mmol) of '-difluorobenzophenone was added, purged with nitrogen, dehydrated at 180 ° C. in 90 mL of N-methylpyrrolidone (NMP) and 45 mL of toluene, heated to remove toluene, 1 at 230 ° C. Time polymerization was performed. Purification was performed by reprecipitation with a large amount of water to obtain a prepolymer represented by the general formula (G16). The weight average molecular weight was 50,000.

(Polymerization of block copolymer)
In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 6.91 g of potassium carbonate (Aldrich reagent, 50 mmol) and 8.73 g (20 mmol) of the prepolymer, K- obtained in Synthesis Example 1 were used. DHBP 10.33 g (40 mmol), 4,4′-difluorobenzophenone 3.49 g (Aldrich reagent, 16 mmol), and sulfonimide potassium salt (G3) 17.20 g (24 mmol) obtained in Example 1 were charged with nitrogen. Then, after dehydrating at 180 ° C. in 120 mL of N-methylpyrrolidone (NMP) and 45 mL of toluene, the temperature was raised to remove toluene, and polymerization was carried out at 230 ° C. for 10 hours. Purification was performed by reprecipitation with a large amount of water to obtain a block polymer. The weight average molecular weight was 290,000.

  The block polymer has a prepolymer block (A2) having the general formula (G16) as a repeating unit, a structure represented by the general formula (G16) of 0.4, K-DHBP and sulfonimide potassium salt (G3 ) Is formed from a block (A1) of repeating units having a structure linked with an ether group produced by reaction of 0.6.

The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness: 23 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing block polymer. The ion exchange capacity determined from neutralization titration was 1.7 mmol / g. Further, no ketal group remained from ¹ H-NMR.

  It was an extremely tough electrolyte membrane, and was a membrane that was visually cloudy. The proton conductivity was 250 mS / cm at 80 ° C. and 85% relative humidity, and 1.5 mS / cm at 80 ° C. and 25% relative humidity, and was excellent in low humidified proton conductivity. Further, the dimensional change rate was relatively small at 9%, and the hot water resistance was also excellent. In TEM observation, a phase separation structure having a domain size of 250 nm was confirmed.

Example 15
(Synthesis of oligomer a1 ′ not containing an ionic group represented by the following general formula (G17))
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1 and 4,4 20.3 g of '-difluorobenzophenone (Aldrich reagent, 93 mmol) was added, purged with nitrogen, dehydrated at 160 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, heated to remove toluene, 1 at 180 ° C. Time polymerization was performed. Reprecipitation purification was performed in a large amount of methanol to obtain an oligomer a1 (terminal: hydroxyl group) containing no ionic group. The number average molecular weight was 10,000.

  In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 1.1 g of potassium carbonate (Aldrich reagent, 8 mmol) and 20.0 g of the oligomer a1 not containing an ionic group (terminal: hydroxyl group) (2 mmol) was added, and after nitrogen substitution, dehydration was performed at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, followed by heating to remove cyclohexane, and 4.0 g of decafluorobiphenyl (Aldrich reagent, 12 mmol) was added. The reaction was carried out at 105 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a1 '(terminal: fluoro group) not containing an ionic group represented by the following formula (G17). The number average molecular weight was 11000, and the number average molecular weight of the oligomer a1 'not containing an ionic group was determined to be 10400 obtained by subtracting the linker moiety (molecular weight 630).

(Synthesis of oligomer a2 containing an ionic group represented by the following general formula (G18))
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 12.9 g (50 mmol) of K-DHBP obtained in Synthesis Example 1 and 4,4 9.3 g of '-biphenol (Aldrich reagent, 50 mmol), 66.7 g (93 mmol) of the sulfonimide potassium salt (G3) obtained in Example 1, and 18-crown-6, 17.9 g (82 mmol of Wako Pure Chemical Industries, Ltd.) Then, after nitrogen substitution, dehydration was performed at 170 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, and the temperature was raised to remove toluene, and polymerization was performed at 180 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a2 (terminal: hydroxyl group) containing an ionic group represented by the following formula (G18). The number average molecular weight was 16000.

(Synthesis of oligomer a2 as segment (A1) containing a sulfonimide group, oligomer a1 as segment (A2) not containing an ionic group, and block copolymer b1 containing octafluorobiphenylene as a linker moiety)
In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 0.56 g of potassium carbonate (Aldrich reagent, 4 mmol) and 16 g (1 mmol) of oligomer a2 containing ionic groups (terminal: hydroxyl group) After substitution with nitrogen, dehydration was performed at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, followed by heating to remove cyclohexane, 11 g of oligomer a1 ′ (terminal: fluoro group) not containing an ionic group (1 mmol) was added and reacted at 105 ° C. for 24 hours. A block copolymer b1 was obtained by reprecipitation purification into a large amount of isopropyl alcohol. The weight average molecular weight was 490,000.

  The block polymer b1 contains 50 mol% of the segment represented by the general formula (P1) as a segment (A1) containing a sulfonimide group, and the general formula (P2) as a segment (A2) containing no ionic group. ) Was included at 100 mol%. The obtained block polymer b1 was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing block polymer.

The ion exchange capacity determined from neutralization titration was 1.6 meq / g, the molar composition ratio determined from ¹ H-NMR (A1 / A2) was 48 mol / 52 mol = 0.92, and the remaining ketal group was observed. There wasn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 300 mS / cm at 80 ° C. and 85% relative humidity, and 4.5 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent in low humidification proton conductivity. Further, the dimensional change rate was as small as 7%, and the hot water resistance was also excellent. Furthermore, a TEM observation confirmed a co-continuous phase separation structure with a domain size of 30 nm.

Example 16
(Synthesis of oligomer a3 ′ not containing an ionic group represented by the general formula (G17))
Synthesis of oligomer a3 (terminal hydroxyl group) containing no ionic group was carried out by the method described in Example 15 except that the amount of 4,4′-difluorobenzophenone charged was changed to 21.4 g (Aldrich reagent, 98 mmol). went. The number average molecular weight was 20000.

Further, Example 15 was prepared except that 40.0 g (2 mmol) of the oligomer a3 (terminal: hydroxyl group) containing no ionic group was charged instead of the oligomer a1 (terminal: hydroxyl group) containing no ionic group. The oligomer a3 ′ (terminal fluoro group) not containing the ionic group represented by the formula (G17) was synthesized by the method described in (1). The number average molecular weight was 21000, and the number average molecular weight of the oligomer a5 ′ not containing an ionic group was determined to be 20400 obtained by subtracting the linker moiety (molecular weight 630).
(Synthesis of oligomer a4 containing an ionic group represented by the following general formula (G19))
The sulfonimide potassium salt (G3) is represented by the following formula (G19) by the method described in Example 15 except that the sulfonimide potassium salt (G4) obtained in Example 2 is changed to 101 g (95 mmol). An oligomer a4 (terminal hydroxyl group) containing an ionic group was obtained. The number average molecular weight was 23000.

(In the formula, * represents a binding site with another site)
(Synthesis of oligomer a4 as a segment (A1) containing a sulfonimide group, oligomer a3 as a segment (A2) not containing an ionic group, and a block copolymer b2 containing octafluorobiphenylene as a linker moiety)
In place of the ionic group-containing oligomer a2 (terminal hydroxyl group), 23 g (1 mmol) of the ionic group-containing oligomer a4 (terminal hydroxyl group) was added, and the ionic group-free oligomer a1 ′ (terminal fluoro) The block copolymer b2 was obtained by the method described in Example 15 except that 20 g (1 mmol) of the oligomer a3 ′ (terminal fluoro group) not containing an ionic group was added instead of the group. The weight average molecular weight was 390,000.

  The block polymer b1 contains 50 mol% of the segment represented by the general formula (P1) as a segment (A1) containing a sulfonimide group, and the general formula (P2) as a segment (A2) containing no ionic group. ) Was included at 100 mol%. The obtained block polymer b2 was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing block polymer.

The ion exchange capacity determined from neutralization titration was 2.0 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 30 mol / 70 mol = 0.43, and the ketal group remained. There wasn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 500 mS / cm at 80 ° C. and 85% relative humidity, and 6 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent in low humidification proton conductivity. Further, the dimensional change rate was as small as 13%, and the hot water resistance was also excellent. Furthermore, a phase separation structure with a domain size of 45 nm was confirmed by TEM observation.

Example 17
(Synthesis of oligomer a4 as segment (A1) containing sulfonimide group, oligomer a1 as segment (A2) not containing ionic group, and block copolymer b3 containing octafluorobiphenylene as linker moiety)
In the method described in Example 15, except that 23 g (1 mmol) of the oligomer a4 (terminal hydroxyl group) containing an ionic group was added instead of the oligomer a2 (terminal hydroxyl group) containing an ionic group. Copolymer b3 was obtained. The weight average molecular weight was 400,000.

The block polymer b3 contains 50 mol% of the segment represented by the general formula (P1) as a segment (A1) containing a sulfonimide group, and the general formula (P2) as a segment (A2) not containing an ionic group. ) Was included at 100 mol%. The obtained block polymer b3 was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing block polymer.
The ion exchange capacity determined from neutralization titration was 2.7 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 45 mol / 55 mol = 0.82, and the ketal group remained. There wasn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 700 mS / cm at 80 ° C. and 85% relative humidity, and 15 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent. Further, the dimensional change rate was relatively small at 25%, and the hot water resistance was also excellent. Furthermore, a TEM observation confirmed a co-continuous phase separation structure with a domain size of 40 nm.

Example 18
(Synthesis of oligomer a5 ′ not containing an ionic group represented by the following general formula (G20))
The amount of K-DHBP was changed from 25.8 g (100 mmol) to 12.9 g (50 mmol), and the method described in Example 15 was used except that 9.31 g (50 mmol) of 4,4′-biphenol was additionally added. An oligomer a5 (terminal hydroxyl group) containing no ionic group was synthesized. The number average molecular weight was 10,000.

  Further, Example 15 was prepared except that 20.0 g (2 mmol) of the oligomer a5 (terminal: hydroxyl group) containing no ionic group was charged instead of the oligomer a1 (terminal: hydroxyl group) containing no ionic group. The oligomer a5 ′ (terminal fluoro group) not containing an ionic group represented by the following formula (G20) was synthesized by the method described in 1). The number average molecular weight was 11000, and the number average molecular weight of the oligomer a5 'not containing an ionic group was determined to be 10400, which is obtained by subtracting the linker moiety (molecular weight 630).

(Synthesis of oligomer a2 as segment (A1) containing a sulfonimide group, oligomer a5 as segment (A2) not containing an ionic group, and block copolymer b4 containing octafluorobiphenylene as a linker moiety)
The method described in Example 15 except that 11 g (1 mmol) of the oligomer a5 ′ (terminal fluoro group) not containing an ionic group was added instead of the oligomer a1 ′ (terminal fluoro group) containing no ionic group, A block copolymer b4 was obtained. The weight average molecular weight was 350,000.

  The block polymer b3 contains 50 mol% of the segment represented by the general formula (P1) as a segment (A1) containing a sulfonimide group, and the general formula (P2) as a segment (A2) not containing an ionic group. ) Was contained in an amount of 50 mol%. The obtained block polymer b4 was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing block polymer.

The ion exchange capacity determined from neutralization titration was 1.6 meq / g, the molar composition ratio determined from ¹ H-NMR (A1 / A2) was 48 mol / 52 mol = 0.92, and the remaining ketal group was observed. There wasn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 280 mS / cm at 80 ° C. and 85% relative humidity, and 4 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent. Further, the dimensional change rate was as small as 9%, and the hot water resistance was also excellent. Furthermore, a TEM observation confirmed a co-continuous phase separation structure with a domain size of 33 nm.

Example 19
(Synthesis of oligomer a6 containing an ionic group represented by the general formula (G19))
Except that the sulfonimide potassium salt (G3) was changed to 98.5 g (93 mmol) of the sulfonimide potassium salt (G4) obtained in Example 2, it was represented by the formula (G19) according to the method described in Example 15. The oligomer a6 (terminal hydroxyl group) containing the ionic group to be obtained was obtained. The number average molecular weight was 16000.
(Synthesis of oligomer a6 as a segment (A1) containing a sulfonimide group, oligomer a1 as a segment (A2) not containing an ionic group, and a block copolymer b5 containing octafluorobiphenylene as a linker moiety)
In the same manner as in Example 15, except that 16 g (1 mmol) of the oligomer a6 (terminal hydroxyl group) containing an ionic group was added instead of the oligomer a2 (terminal hydroxyl group) containing an ionic group, the block co-polymerization was performed. A polymer b5 was obtained. The weight average molecular weight was 380,000.

  The block polymer b5 contains 50 mol% of the segment represented by the general formula (P1) as a segment (A1) containing a sulfonimide group, and the general formula (P2) as a segment (A2) not containing an ionic group. ) Was included at 100 mol%. The obtained block polymer b5 was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing block polymer.

The ion exchange capacity determined from neutralization titration was 2.4 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 37 mol / 63 mol = 0.59, and the ketal group remained. There wasn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 600 mS / cm at 80 ° C. and a relative humidity of 85%, and 10 mS / cm at 80 ° C. and a relative humidity of 25%. The proton conductivity was excellent. Further, the dimensional change rate was as small as 18%, and the hot water resistance was also excellent. Furthermore, a phase separation structure with a domain size of 35 nm was confirmed by TEM observation.

Example 20
(Synthesis of oligomer a7 containing an ionic group represented by the following general formula (G21))
Except that the sulfonimide potassium salt (G3) was changed to 114.5 g (93 mmol) of the sulfonimide potassium salt (G5) obtained in Example 3 above, it was represented by the following formula (G21) by the method described in Example 15. The oligomer a7 (terminal hydroxyl group) containing the ionic group to be obtained was obtained. The number average molecular weight was 16000.

(In the formula, * represents a binding site with another site)
(Synthesis of oligomer a7 as segment (A1) containing sulfonimide group, oligomer a1 as segment (A2) not containing ionic group, and block copolymer b6 containing octafluorobiphenylene as a linker moiety)
In the same manner as in Example 15 except that 16 g (1 mmol) of the oligomer a7 (terminal hydroxyl group) containing an ionic group was added instead of the oligomer a2 (terminal hydroxyl group) containing an ionic group, A polymer b6 was obtained. The weight average molecular weight was 390,000.

  The block polymer b6 contains 50 mol% of the segment represented by the general formula (P1) as a segment (A1) containing a sulfonimide group, and the segment represented by the general formula (P2) as a segment (A2) not containing an ionic group. ) Was included at 100 mol%. The obtained block polymer b6 was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonimide group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonimide group-containing block polymer.

The ion exchange capacity determined from neutralization titration was 1.9 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 32 mol / 68 mol = 0.47, and the remaining ketal group was observed. There wasn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 680 mS / cm at 80 ° C. and 85% relative humidity, and 16 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent. Further, the dimensional change rate was as small as 15%, and the hot water resistance was also excellent. Furthermore, a phase separation structure with a domain size of 38 nm was confirmed by TEM observation.

Comparative Example 1 Various characteristics were evaluated using a commercially available Nafion (registered trademark) NRE211CS membrane (manufactured by DuPont). The ion exchange capacity determined from neutralization titration was 0.9 meq / g. The film was visually transparent and uniform, and a clear phase separation structure was not confirmed by TEM observation. The proton conductivity was 100 mS / cm at 80 ° C. and 85% relative humidity, and 3 mS / cm at 80 ° C. and 25% relative humidity. Moreover, when it was immersed in hot water, it swelled violently, and it was difficult to handle and sometimes it was torn.

Comparative Example 2
(Sulfonic acid group-containing polymer represented by the following general formula (G22))

  In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 23.2 g of potassium carbonate (Aldrich reagent, 168 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and the above synthesis example Disodium-3,3′-disulfonate-4,4′-difluorobenzophenone obtained in 2 above (52.5 mmol), 11.1 g of 4,4′-difluorobenzophenone (Aldrich reagent, 51 mmol) and 18-crown- 6. After 12.2 g (46.2 mmol of Wako Pure Chemical Industries, Ltd.) were added, after nitrogen substitution, dehydration was performed at 180 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, and then the temperature was raised to remove toluene, and 3 at 210 ° C. Time polymerization was performed. Purification was performed by reprecipitation in a large amount of isopropyl alcohol to obtain a precursor polymer having a ketal group. The weight average molecular weight was 310,000.

  The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness: 24 μm). The solubility of the sulfonic acid group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonic acid group-containing polymer. The ion exchange capacity determined from neutralization titration was 2.1 mmol / g.

It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. Proton conductivity was 130 mS / cm at 80 ° C. and 85% relative humidity, and 0.2 mS / cm at 80 ° C. and 25% relative humidity. On the other hand, the dimensional change rate was relatively small at 8%, and the hot water resistance was excellent. In addition, the presence of a ketal group was not observed in NMR.

Comparative Example 3
(Sulfonic acid group-containing polymer represented by the following general formula (G23))

  In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 21.4 g of potassium carbonate (Aldrich reagent, 155 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and the above synthesis example 17.2 g (40.8 mmol) of disodium-3,3′-disulfonate-4,4′-difluorobenzophenone obtained in 2), 13.1 g (Aldrich reagent, 60 mmol) of 4,4′-difluorobenzophenone and 18-crown- 6, 9.48 g (35.9 mmol of Wako Pure Chemicals) was added, and after nitrogen substitution, dehydration was performed at 180 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, and the temperature was raised to remove toluene. Time polymerization was performed. Purification was performed by reprecipitation in a large amount of isopropyl alcohol to obtain a precursor polymer having a ketal group. The weight average molecular weight was 340,000.

  The obtained precursor polymer was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness: 24 μm). The solubility of the sulfonic acid group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane made of a sulfonic acid group-containing polymer. The ion exchange capacity determined from neutralization titration was 1.8 mmol / g.

  It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 105 mS / cm at 80 ° C. and 85% relative humidity, and 0.09 mS / cm at 80 ° C. and 25% relative humidity, which was inferior to the examples. On the other hand, the dimensional change rate was as small as 6% and excellent in hot water resistance. In addition, the presence of a ketal group was not observed in NMR.

Comparative Example 4
According to the method described in Non-Patent Document 1 and Example 1, a polyethersulfone-based sulfonimide-containing polymer was synthesized.

  (Aromatic sulfonimide derivative represented by the following formula (G24))

In a 1 L flask equipped with a stirrer, 155 g of 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone was weighed in a nitrogen stream, dissolved in 330 mL of acetonitrile and 250 mL of sulfolane, and further added 290 g of phosphoryl trichloride, After heating to reflux for 2 hours, 20 mL of N, N-dimethylacetamide was added and heated to reflux for 16 hours. After cooling with ice, 1.5 L of cold water was added, and the resulting precipitate was collected by filtration and washed with 500 mL of cold water. The precipitate was dried at room temperature under reduced pressure, and recrystallized with toluene at 300 mL to obtain 76 g of 5,5′-sulfonylbis (2-chlorobenzene-1-sulfonyl chloride). The structure was confirmed by ¹ H-NMR.

Dissolve 38.7 g of 5,5′-sulfonylbis (2-chlorobenzene-1-sulfonyl chloride) and 26.6 g of trifluoromethanesulfonamide in 250 mL of dehydrated acetone, and ice-cool it. Then, 54 mL of triethylamine is added dropwise under nitrogen. The mixture was stirred at room temperature for 24 hours. After the triethylammonium chloride precipitate was separated by filtration, the filtrate was concentrated on a rotary evaporator, diluted with 400 mL of ethyl acetate and washed twice with 200 mL of 1N HCl. The organic phase was dried over sodium sulfate and the solvent removed to give the acidic sulfonimide crude product as a reddish brown viscous liquid. The product was redissolved in methanol / water (200/75 mL) and treated with 13.82 g K2CO3 dissolved in 14 ml water. The solution was filtered off, concentrated to about 100 mL and gradually cooled. The precipitate was collected by filtration, washed with water, dried, and recrystallized with ethanol to obtain 42.2 g of sulfonimide potassium salt (G24). The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

  (Sulfonimide group-containing polymer represented by the following general formula (G25))

  In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 11.6 g of potassium carbonate (Aldrich reagent, 84 mmol), 9.41 g (50 mmol) of biphenol, and 23.6 g of the sulfonimide derivative (G24) were used. (30 mmol), 5.74 g of 4,4′-dichlorodiphenylsulfone (Aldrich reagent, 20 mmol) were added, and after nitrogen substitution, dehydration was performed at 130 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, and the temperature was raised. The toluene was removed, and polymerization was carried out at 190 ° C. for 16 hours and at 205 ° C. for 2 hours. Purification was carried out by reprecipitation in a large amount of isopropyl alcohol to obtain a potassium salt type sulfonimide-containing polymer. The weight average molecular weight was 280,000. The obtained polymer was formed into a film by the method described in Example 6 to obtain a polymer film (film thickness: 25 μm). Subsequently, proton replacement and water washing were performed according to the method described in Example 6, and the above-described formula (G25) was described. A polymer electrolyte membrane made of a sulfonimide group-containing polymer was obtained. The ion exchange capacity determined from neutralization titration was 1.9 mmol / g.

Although it was a hard and brittle electrolyte membrane, it was a transparent and uniform membrane by visual observation. The proton conductivity was 190 mS / cm at 80 ° C. and a relative humidity of 85%, and 0.6 mS / cm at 80 ° C. and a relative humidity of 25%, which was particularly inferior to the low humidified proton conductivity. Further, the dimensional change rate was as large as 55%, and the hot water resistance was inferior.

Comparative Example 5 According to the method described in US Patent Application Publication No. 2008-0286626 and Example 1, a sulfonimide group-containing polymer having a terminal substituted with a phenyl group was synthesized.

  (Aromatic sulfonimide derivative represented by the following formula (G26))

In a 500 mL flask equipped with a stirrer, 66.5 g of 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 2 was weighed in a nitrogen stream and dissolved in 165 mL of acetonitrile and 125 mL of sulfolane. Further, 145 g of phosphoryl trichloride was added and heated to reflux for 2 hours, and then 10 mL of N, N-dimethylacetamide was added and heated to reflux for 16 hours. After cooling with ice, 750 mL of cold water was added, and the resulting precipitate was collected by filtration and washed with 250 mL of cold water. The precipitate was dried under reduced pressure at room temperature, and recrystallized with 150 mL of toluene to obtain 32.0 g of 5,5′-carbonylbis (2-fluorobenzene-1-sulfonyl chloride). The structure was confirmed by ¹ H-NMR.

When 16.6 g of 5,5′-carbonylbis (2-fluorobenzene-1-sulfonyl chloride) and 14.0 g of phenylsulfonamide were dissolved in 125 mL of dehydrated acetone and ice-cooled, 27 mL of triethylamine was added dropwise under nitrogen. The mixture was stirred at room temperature for 24 hours. After the triethylammonium chloride precipitate was separated by filtration, the filtrate was concentrated by rotary evaporator, diluted with 200 mL of ethyl acetate and washed twice with 100 mL of 1N HCl. The organic phase was dried over sodium sulfate and the solvent was removed to give a crude acidic sulfonimide product. The product was redissolved in methanol / water (100/38 mL) and treated with 6.91 g K2CO3 dissolved in 7 ml water. The solution was filtered off, concentrated to about 50 mL and slowly cooled. The precipitate was collected by filtration, washed with water, dried, and recrystallized and purified with ethanol to obtain 22.0 g of sulfonimide potassium salt (G26). The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

  (Sulfonimide group-containing polymer represented by the following general formula (G27))

  In a 500 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube and a Dean-Stark trap, 11.6 g of potassium carbonate (Aldrich reagent, 84 mmol), 13.4 g (50 mmol) of 4,4′-cyclohexylidenebisphenol, sulfonimide derivative 25.7 g (35 mmol) of (G26) and 3.27 g of 4,4′-difluorobenzophenone (Aldrich reagent, 15 mmol) were added, and after nitrogen replacement, 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene at 180 ° C. After dehydration, the temperature was raised to remove toluene, and polymerization was carried out at 210 ° C. for 3 hours. Purification was carried out by reprecipitation in a large amount of isopropyl alcohol to obtain a potassium salt type sulfonimide-containing polymer. The weight average molecular weight was 290,000.

  The obtained polymer was formed into a film by the method described in Example 6 to obtain a polymer film (film thickness: 26 μm). Subsequently, proton replacement and water washing were performed according to the method described in Example 6, and the above-described formula (G27) was described. A polymer electrolyte membrane made of a sulfonimide group-containing polymer was obtained. The ion exchange capacity determined from neutralization titration was 1.8 mmol / g.

Although it was a hard and brittle electrolyte membrane, it was a transparent and uniform membrane by visual observation. The proton conductivity was 170 mS / cm at 80 ° C. and a relative humidity of 85%, and 0.3 mS / cm at 80 ° C. and a relative humidity of 25%, which was particularly inferior to the low humidified proton conductivity. Further, the dimensional change rate was as large as 80%, and the hot water resistance was inferior.

Comparative Example 6 A sulfonimide group-containing block polymer was synthesized according to the method described in JP-A-2008-163160.

  (Aromatic sulfonimide derivative represented by the following formula (G28))

  To a solution of 3- (2,5-dichlorobenzoyl) benzenesulfonyl chloride (27.97 g, 80 mmol) and trifluoromethanesulfonamide (13.30 g, 87 mmol) in dehydrated acetone (250 mL) was added triethylamine (27 mL, 200 mmol). Was added dropwise to the ice-cold solution under nitrogen and the reaction mixture was stirred at room temperature for 24 hours. After the triethylammonium chloride precipitate was separated by filtration, the filtrate was concentrated by rotary evaporator, diluted with ethyl acetate (400 mL) and washed with 1N HCl (2 × 200 mL). The organic phase was dried over MgSO4 and the solvent was removed to give the acidic sulfonic acid imide crude product as a brown oil. The product was redissolved in methanol / water (200/75 mL) and treated with K2CO3 (6.91 g, 50 mmol, dissolved in 7 ml water). The solution was filtered off, concentrated to about 100 mL and slowly cooled. The precipitate was collected by filtration, washed with water, dried and recrystallized with ethanol using activated carbon to obtain 29 g of sulfonic acid imide potassium salt (G28).

(2-Chlorobenzonitrile-terminated poly (ether nitrile) oligomer)
4,4′-dichlorodiphenylsulfone (12.92 g, 45 mmol), 4,4′-
A mixture of dihydroxydiphenylsulfone (12.51 g, 50 mmol) and K 2 CO 3 (8.29 g, 60 mmol) was azeotroped with toluene / water in NMP / toluene (50/30 mL) at 180 ° C. for 8 hours under nitrogen atmosphere. While collecting the mixture in a Dean-Stark trap, stirring was performed until formation of the hydroxyl-terminated oligomer was completed. The reaction mixture was cooled to 80 ° C., 2-chloro-6-fluorobenzonitrile (3.11 g, 20 mmol) was added in one portion and further stirred at 165 ° C. for 4 hours. The polycondensation product was precipitated and separated in methanol and fractionated by stirring in THF (300 mL) to obtain a 2-chlorobenzonitrile-terminated poly (ether nitrile) oligomer. ^{By 1} H-NMR, it was confirmed that the oligomer was quantitatively end-capped with a chlorobenzonitrile group, and impurities were quantitatively analyzed by capillary electrophoresis (organic substance) and ion chromatography (inorganic substance). The number average molecular weight was 8,000.

(Sulfonimide-containing block copolymer)
Aromatic sulfonimide derivative (G28) (14.0 g, 28.0 mmol), 2-chlorobenzonitrile-terminated poly (ether nitrile) oligomer (Mn = 8000, 8.32 g, 1.04 mmol), Ni (PPh3) 2Cl2 ( 0.57 g, 0.87 mmol), PPh3 (3.05 g, 11.61 mmol), NaI (0.13 g, 0.87 mmol), Zn dust (4.74 g, 72.6 g) 45 mL) was added under a stream of nitrogen and the reaction mixture was stirred at 80 ° C. for 4 hours. The resulting thick suspension was diluted with THF and filtered through a celite pad to remove excess Zn. Toluene and hexane were sequentially added to the filtrate to precipitate the crude polymer as the potassium salt. The powdered product was stirred with high-temperature (80 ° C.) 2N H 2 SO 4 for 2 hours, filtered at high temperature, repeatedly washed until pH> 6, stirred in boiling water for 20 hours, filtered and dried, A sulfonimide-containing block copolymer was obtained. The weight average molecular weight was 270,000.

  After the obtained polymer was dissolved in a mixed solution of NMP / methanol = 2/1, a film was cast on a glass substrate, dried in an oven at 80 ° C. for 30 minutes, then peeled off from the substrate, and further at 140 ° C. After drying for 30 minutes, a polymer electrolyte membrane made of a sulfonimide group-containing polymer was obtained (film thickness: 24 μm. The ion exchange capacity determined from neutralization titration was 1.8 mmol / g.

  Although it was a hard and brittle electrolyte membrane, it was a transparent and uniform membrane by visual observation. The proton conductivity was 220 mS / cm at 80 ° C. and a relative humidity of 85%, and 1.2 mS / cm at 80 ° C. and a relative humidity of 25%. In particular, the proton conductivity was inferior to the low-humidity proton conductivity. . Further, the dimensional change rate was as large as 55%, and the hot water resistance was inferior to that of the examples. A TEM observation confirmed a phase separation structure with a domain size of 27 nm.

Comparative Example 7
(Synthesis of oligomer c1 containing an ionic group represented by the following general formula (G29))
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 12.9 g (50 mmol) of K-DHBP obtained in Synthesis Example 1 and 4,4 9.3 g of '-biphenol (Aldrich reagent, 50 mmol), 38.0 g (90 mmol) of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 2, and 18-crown-6, Add 17.3 g (79 mmol of Wako Pure Chemical Industries), replace with nitrogen, dehydrate at 170 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, remove the toluene by heating, and perform polymerization at 180 ° C. for 1 hour. It was. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer c1 (terminal: hydroxyl group) containing an ionic group represented by the following formula (G29). The number average molecular weight was 14,000.

(In the formula (G29), M represents Na or K.)
(Synthesis of oligomer c1 as segment (A1) containing ionic group, oligomer a1 as segment (A2) not containing ionic group, and block copolymer d1 containing octafluorobiphenylene as a linker moiety)
In the same manner as in Example 15 except that 14 g (1 mmol) of the oligomer c1 (terminal hydroxyl group) containing an ionic group was added instead of the oligomer a2 (terminal hydroxyl group) containing an ionic group, A polymer d1 was obtained. The weight average molecular weight was 300,000.

  The block polymer d1 includes a segment represented by the general formula (P1) as a segment (A1) containing a sulfonimide group, a segment (A2) not containing an ionic group as a segment represented by the general formula (P2). ) Was included at 100 mol%. The obtained block polymer d1 was formed into a film by the method described in Example 6 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonic acid group-containing polymer before molding was very good. Subsequently, proton substitution and water washing were performed by the method described in Example 6 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing block polymer.

The ion exchange capacity determined from neutralization titration was 1.4 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 45 mol / 55 mol = 0.81, and the ketal group remained. There wasn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 160 mS / cm at 80 ° C. and 85% relative humidity, and 0.5 mS / cm at 80 ° C. and 25% relative humidity. Since it did not contain a sulfonimide group, it was inferior to the examples, but as a sulfonic acid group-containing polymer and a low ion exchange capacity, it was excellent in low humidification proton conductivity. Further, the dimensional change rate was as small as 5%, and the hot water resistance was also excellent. Furthermore, a co-continuous phase separation structure with a domain size of 15 nm was confirmed by TEM observation.

  The sulfonimide group-containing polymer and polymer electrolyte material of the present invention can be applied to various electrochemical devices (for example, fuel cells, water electrolysis devices, chloroalkali electrolysis devices, etc.). Among these devices, it is suitable for a fuel cell, and particularly suitable for a fuel cell using hydrogen as a fuel.

  Applications of the polymer electrolyte fuel cell of the present invention are not particularly limited, but are portable devices such as mobile phones, personal computers, PDAs, video cameras, digital cameras, home appliances such as cordless vacuum cleaners, toys, electric bicycles, automatic It is preferably used as a power supply source for vehicles such as motorcycles, automobiles, buses, trucks, etc., moving bodies such as ships, railways, etc., conventional primary batteries such as stationary generators, alternatives to secondary batteries, or hybrid power sources with these. .

Claims (14)

An aromatic sulfonimide derivative represented by the following general formula (M1):

(In formula (M1), R ¹ and R ² each independently represents a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups. M ¹ M ² represents a cation species selected from hydrogen, a metal cation, and an ammonium cation, and X ¹ and X ² represent a halogen atom.) The aromatic sulfonimide derivative according to claim 1, wherein the general formula (M1) is represented by the following general formula (M2).

(In Formula (M2), R ¹ and R ² each independently represent a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups. M ¹ M ² represents a cation species selected from hydrogen, a metal cation, and an ammonium cation, and X ¹ and X ² represent a halogen atom.) The aromatic sulfonimide derivative according to claim 1 or 2, wherein the aromatic group has 4 to 20 carbon atoms. The aromatic sulfonimide derivative according to claim 1, wherein the ionic group is a sulfonic acid group or a sulfonimide group. The aromatic sulfonimide derivative according to any one of claims 1 to 4, wherein the perfluoroalkyl group has 1 to 20 carbon atoms. A sulfonimide group-containing polymer obtained by polymerization using the aromatic sulfonimide derivative according to any one of claims 1 to 5. The sulfonimide group-containing polymer according to claim 6, comprising a structural unit represented by the following general formula (P1).

(In formula (P1), R ¹ and R ² each independently represents a substituent selected from the group consisting of perfluoroalkyl groups or the group consisting of aromatic groups containing ionic groups. M ¹ M ² represents a cation species selected from hydrogen, a metal cation, and an ammonium cation.) The sulfonimide group-containing polymer according to claim 7, wherein the content of the structural unit represented by the general formula (P1) is 20% by weight or more. The copolymer has a segment (A1) having at least a structural unit represented by the general formula (P1) and a segment (A2) having a structural unit not containing an ionic group, and the copolymerization mode is block copolymerization. Or the sulfonimide group containing polymer of 8. The sulfonimide group-containing polymer according to claim 9, wherein the structural unit not containing the ionic group is represented by the following general formula (P2).

(In the general formula (P2), Ar ^{1 to} Ar ⁴ represent an arbitrary divalent arylene group and may be optionally substituted, but do not contain an ionic group. Ar ^{1 to} Ar ⁴ are independent of each other. Two or more types of arylene groups may be used, and * represents a bonding site with the general formula (P2) or other structural unit.) 11. The sulfonimide group-containing polymer according to claim 10, wherein the structural unit represented by the general formula (P2) is represented by the following formula (P3).

A polymer electrolyte material comprising the sulfonimide group-containing polymer according to any one of claims 6 to 11. A polymer electrolyte molded body comprising the polymer electrolyte material according to claim 12. A polymer electrolyte fuel cell comprising the polymer electrolyte material according to claim 12.