JP2018060789A - Polymer electrolyte composition and polymer electrolyte membrane prepared therewith, electrolyte membrane with catalyst layer, membrane electrode complex, solid polymer fuel cell, electrochemical hydrogen pump and water-electrolytic hydrogen generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte composition that suppresses the elution of an antioxidant even during the operation of a fuel cell for a long time has high chemical stability.SOLUTION: A polymer electrolyte composition contains an ionic group-containing polymer (A), and a phosphorus-containing polymer (B) having a structure selected from the group consisting of the general formulas (C1), (C2) and (C3) (where Ris any divalent organic group, and Ris any monovalent organic group. R-Rmay be bound to each other to form a ring structure. A plurality of R's and R's in the polymer chain are may be the same or different).SELECTED DRAWING: None

Description

  The present invention relates to a polymer electrolyte composition, a polymer electrolyte membrane using the same, a solid polymer fuel cell, an electrochemical hydrogen pump, and a water electrolysis hydrogen generator.

  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 generally referred to as a membrane electrode assembly (hereinafter abbreviated as MEA). The cell is configured as a unit in which the MEA is sandwiched between separators. The main component of the polymer electrolyte membrane is an ionic group-containing polymer (polymer electrolyte material), but an additive or the like can be blended in order to improve durability.

  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 functions as a barrier that prevents direct reaction between the 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.

  Until now, Nafion (registered trademark) (manufactured by DuPont), which is a perfluorosulfonic acid polymer, has been widely used for polymer electrolyte membranes. Since Nafion (registered trademark) is manufactured through multi-step synthesis, it is very expensive, and there is a problem that fuel crossover (fuel permeation amount) is 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. On the other hand, development of hydrocarbon-based electrolyte membranes has recently been activated as a polymer electrolyte membrane that can replace Nafion (registered trademark) and is inexpensive and excellent in membrane characteristics.

  However, any of these polymer electrolyte membranes has a problem of insufficient chemical stability when used in a polymer electrolyte fuel cell. The mechanism related to chemical degradation has not yet been fully elucidated, but hydrogen peroxide, which has strong oxidizing power generated during power generation, and a trace amount of metal such as iron that can exist in the system reacts with hydrogen peroxide. As a result of the polymer main chain and side chain being cleaved by the generated hydroxy radical, etc., the polymer electrolyte membrane becomes thin, weakened, fuel permeation increases, hydrogen peroxide, hydroxy radical, etc. are further generated, It is believed that film degradation proceeds at an accelerated rate. In addition, the polymer electrolyte membrane that has become fragile is damaged while it repeatedly swells and contracts in accordance with changes in humidity.

  Under such circumstances, studies are being made to improve chemical stability and durability by using a polymer electrolyte membrane in which an antioxidant is blended with a perfluoro-based electrolyte membrane or a hydrocarbon-based electrolyte membrane.

  For example, Patent Documents 1 and 2 propose a polymer electrolyte membrane to which a phosphorus-based antioxidant is added. Specifically, a phosphonic acid ester (phosphite) antioxidant is blended with a sulfonic acid group-containing polyethersulfone polymer, a polymer electrolyte membrane, or a phosphonic acid group-containing polymer such as polyvinylphosphonic acid. A polymer electrolyte membrane blended with an acid group-containing polyethersulfone polymer or a sulfonic acid group-containing polyetherketone polymer.

  Patent Documents 3 to 5 propose electrolyte membranes to which sulfur-based, amine-based, phenol-based antioxidants and the like are added in addition to phosphorus-based antioxidants. Specifically, antioxidants such as phosphites (phosphites), thioethers, hindered amines, and hindered phenols are blended into sulfonic acid group-containing polyethersulfone polymers and sulfonic acid group-containing polyarylene polymers. The polymer electrolyte membrane.

JP 2003-151346 A JP 2000-11756 A JP 2003-201403 A JP 2007-66882 A JP 2005-213325 A

  However, in the polymer electrolyte membranes described in Patent Documents 1 to 5, there is a problem that the antioxidant is eluted during the operation of the fuel cell for a long time, and the effect is hardly sustained.

  In view of the background of the prior art, the present invention is intended to provide a polymer electrolyte composition having a high chemical stability with little elution of an antioxidant even during operation of a fuel cell for a long time. .

  As a result of intensive studies by the present inventors to overcome the above-mentioned problems, the specific phosphorus-containing polymer (B) is added as an additive to the ionic group-containing polymer (A), particularly for fuel cells, In addition to investigating that excellent chemical durability performance can be achieved when molded into polymer electrolyte membranes for electrochemical hydrogen pumps and water electrolysis hydrogen generators, various studies have been made. Was completed.

  The present invention provides a polymer electrolyte comprising an ionic group-containing polymer (A) and a phosphorus-containing polymer (B) having a structure selected from the group consisting of the following general formulas (C1), (C2) and (C3) It is a composition.

(In each formula, R ₁ represents an arbitrary divalent organic group, R ₂ represents an arbitrary monovalent organic group. R _{1 to} R ₂ are optionally bonded to form a ring structure. The plurality of R ₁ and R ₂ in the polymer chain may be the same or different.)
In the present specification, the “composition” is a general term for a molded article and a liquid composition (solution, dispersion) containing an ionic group-containing polymer (A) and a specific phosphorus-containing polymer (B).

  According to the present invention, there are provided a polymer electrolyte membrane, a membrane electrode assembly, a polymer electrolyte fuel cell, an electrochemical hydrogen pump, and a water electrolysis hydrogen generator having excellent chemical stability that can withstand a strong oxidizing atmosphere. be able to.

[Phosphorus-containing polymer (B)]
The compound used as the phosphorus-containing polymer (B) is a polymer having a phosphorus atom in the main chain, including a structure represented by the following general formula (C1), (C2), or (C3).

(In the formula, R ₁ represents an arbitrary divalent organic group, R ₂ represents an arbitrary monovalent organic group. R _{1 to} R ₂ may be arbitrarily bonded to form a ring structure. A plurality of R ₁ and R ₂ in the polymer chain may be the same or different.)
By using a polymer having a phosphorus atom in the main chain, excellent heat resistance / weather resistance, oxidation resistance / radical resistance can be imparted. In addition, the presence of polar phosphorus atoms improves the solubility in many common solvents and facilitates production and molding.

In the present invention, it is preferable that the phosphorus-containing polymer (B) has a carbon-phosphorus-carbon bond in the main chain from the viewpoint of hydrolysis resistance and elution resistance.
In addition, the organic groups R ₁ and R ₂ in the structure represented by the general formula (C1), (C2) or (C3) preferably do not contain an ionic group from the viewpoint of elution resistance.

Furthermore, it is more preferable that the divalent organic group R ₁ is an aromatic hydrocarbon group in terms of water resistance, chemical stability and production process. Since the phosphorus-containing polymer (B) has an aromatic hydrocarbon group, the phosphorus-containing polymer (B) can be stabilized by electronic interaction between the π electrons of the aromatic hydrocarbon group and the phosphorus atom. Thus, a more stable production process of the polymer electrolyte composition can be constructed. Preferred examples of the organic group R ₁ are phenylene, naphthylene, and anthracylene.

The monovalent organic group R ₂ is preferably a hydrophobic group from the viewpoint of water resistance of the phosphorus-containing polymer (B). Preferable specific examples of R ₂ are an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group or an aromatic hydrocarbon group, and an alkyl group or an aromatic hydrocarbon group is particularly preferable.

Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, i-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, and ethylhexyl. Group, nonyl group, decyl group, cyclopentyl group, cyclohexyl group and adamantyl group are preferred. As the alkenyl group, a vinyl group and an allyl group are preferable. As the alkynyl group, an ethynyl group and a propargyl group are preferable. As the alkoxy group, a methoxy group, an ethoxy group, a trifluoroethoxy group, and a phenoxy group are preferable. The amino group is preferably a diphenylamino group. When R ₂ is an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group or an amino group, the hydrocarbon moiety of R ₂ may have a substituent. Examples of the substituent include a halogen atom, a hydroxy group, an amino group, an aryl group, and a heteroaryl group.

When R ₂ is an aromatic hydrocarbon group, it may be an aryl group or a heteroaryl group. As the aryl group, a phenyl group, a naphthyl group, and an anthryl group are preferable. As the heteroaryl group, a pyrrolyl group, pyrazolyl group, imidazolyl group, phosphoryl group, thienyl group, oxazolyl group, thiazolyl group, pyridyl group, pyrazinyl group, pyrimidinyl group, and pyridazinyl group are preferable. When R ₂ is an aromatic hydrocarbon group, R ₂ may have a substituent. Examples of the substituent include a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, a hydroxy group, an alkoxy group, an amino group, an aryl group, and a heteroaryl group.

R ₂ is preferably a phenyl group or a methyl group from the viewpoint of solubility in an organic solvent and ease of synthesis of a polymer having a high degree of polymerization, and a phenyl group is particularly preferable from the viewpoint of water resistance.

  Among the structures represented by the general formula (C1) or (C2), they are represented by the following (a1) to (a17) from the viewpoint of solubility in a general solvent, mechanical strength, availability of raw materials, and the like. The structure is more preferable, and the structures represented by (a1) and (a10) are particularly preferable from the viewpoint of the synthesis of a polymer having a high polymerization degree and the availability of raw materials. Examples of the structure represented by the general formula (C3) include structures represented by the following (a18) to (a21). From the viewpoint of mechanical strength and availability of raw materials, The structure represented by a17) is particularly preferred.

  The phosphorus-containing polymer (B) preferably has a number average molecular weight of 2,000 or more and 1,000,000 or less by GPC method, and more preferably 10,000 to 100,000. By being a high molecular weight body having a number average molecular weight of 2000 or more, the effect can be maintained without being eluted out of the membrane during operation of the fuel cell, and excellent chemical stability and durability can be obtained. Moreover, when a number average molecular weight exceeds 1 million, it may become impossible to separate and mix with the ionic group-containing polymer (A).

  The weight ratio of phosphorus with respect to all elements contained in the phosphorus-containing polymer (B) is preferably 0.01% or more and 30% or less, more preferably 1% or more and 10% or less. Even if the weight ratio of phosphorus is less than 0.01% or more than 30%, the chemical durability improvement effect tends to be hardly obtained.

  In the polymer electrolyte composition, the content of the phosphorus-containing polymer (B) is preferably 0.02 wt% or more and 10 wt% or less with respect to the ionic group-containing polymer (A), more preferably It is 0.1 weight% or more and 5 weight% or less. If it is less than 0.02% by weight, the durability may be insufficient. On the other hand, if it exceeds 10% by weight, the ionic group-containing polymer (A) may be separated and cannot be mixed.

  The method for blending the phosphorus-containing polymer (B) with the ionic group-containing polymer (A) is not particularly limited, but the phosphorus-containing polymer (B) is dissolved or dispersed in the solution or dispersion of the ionic group-containing polymer (A). The method of producing a mixed solution is preferable, and when producing a molded body, it is preferable to use a method of forming using the mixed solution. In the case of producing a molded body, a method in which a solution in which a phosphorus-containing polymer (B) is dissolved is applied to a polymer electrolyte membrane made of an ionic group-containing polymer (A), or a phosphorus-containing polymer (B) is dissolved. Although a method of immersing the polymer electrolyte membrane made of the ionic group-containing polymer (A) in the liquid thus prepared can be considered, in order to efficiently mix a sufficient amount of the phosphorus-containing polymer (B), a mixed solution in advance is used. The method of producing is preferable.

[Transition metal]
The polymer electrolyte composition of the present invention is at least one selected from Ce, Mn, Ti, Zr, V, Cr, Mo, W, Ru, Co, Rh, Ir, Ni, Pd, Pt, Ag, and Au. It is also preferable to further contain the transition metal. As these transition metals, it is possible to use one or more selected from the simple substance of such transition metals, ions of such transition metals, salts containing such transition metal ions, and oxides of such transition metals.

  Of these, Ce, Mn, V, Mo, W, Ru, Co, Rh, Ir, Ni, Pd, Pt, Ag, and Au are used because of their high functions as radical scavengers and peroxide decomposers. More preferably, Ce, Mn, Ru, Co, Rh, Ir, Ni, Pd, Pt, Ag, Au, more preferably Ce, Mn, Ru, Co, Rh, Ir, Ni, Pd, Pt , Au.

  The content of the transition metal used in the present invention can be appropriately selected in consideration of the balance between power generation characteristics and durability, and is not limited, but is 0 for the ionic group-containing polymer (A). More preferably, the content is 0.01% by weight or more and 15% by weight or less. More preferably, they are 0.05 weight% or more and 3 weight% or less, Most preferably, it is 0.1 weight% or more and 2 weight% or less. If it is less than 0.01% by weight, durability may be insufficient. On the other hand, if it exceeds 15% by weight, proton conductivity may be insufficient.

  Here, when adding the salt and oxide containing a transition metal, content of a transition metal is defined by the transition metal equivalent (only a transition metal part) in a compound.

  Further, the content ratio of the phosphorus-containing polymer (B) and the transition metal used in the present invention can be appropriately selected in consideration of the balance between the power generation characteristics and the durability, and is not limited, but phosphorus / transition More preferably, the molar ratio of the metal is 0.1 or more and 100 or less. More preferably, it is 1 or more and 20 or less, and most preferably 5 or more and 10 or less. When the molar ratio of phosphorus / transition metal is less than 0.1, proton conductivity and water resistance may be insufficient. Moreover, when it exceeds 100, the durability improvement effect may become small.

  Examples of the salt containing a transition metal ion include a salt containing +3 valent cerium ion, a salt containing +4 valent cerium ion, a salt containing +2 valent manganese ion, a salt containing +3 valent manganese ion, and a +2 valent cobalt Examples include salts containing ions. Examples of the salt containing + trivalent cerium ions include cerium acetate, cerium chloride, cerium nitrate, cerium carbonate, and cerium sulfate. Examples of the salt containing +4 valent cerium ions include cerium sulfate and tetraammonium cerium sulfate. Examples of the salt containing +2 valent manganese ions include manganese acetate, manganese chloride, manganese nitrate, manganese carbonate, and manganese sulfate. Examples of the salt containing + trivalent manganese ions include manganese acetate. Examples of the salt containing +2 valent cobalt ions include cobalt chloride, cobalt nitrate, cobalt carbonate, and cobalt sulfate. Of these, cerium nitrate and manganese nitrate are preferably used because they have a high effect of suppressing oxidative degradation.

  The transition metal ion may be present alone or as a complex coordinated with an organic compound. Among these, the complex with the phosphorus-containing polymer (B) of the present invention can suppress elution of additives and ion crosslinking and gelation of the polymer electrolyte composition during operation of the fuel cell (excellent gel resistance). It is preferable from the viewpoint.

  Examples of transition metal oxides include cerium oxide, manganese oxide, ruthenium oxide, cobalt oxide, nickel oxide, chromium oxide, iridium oxide, and lead oxide. Of these, cerium oxide and manganese oxide are preferably used because they have a high effect of suppressing oxidative degradation.

[Ionic group-containing polymer (A)]
The ionic group-containing polymer (A) may be either an ionic group-containing perfluoro polymer or an ionic group-containing hydrocarbon polymer. In the present invention, the ionic group-containing hydrocarbon polymer is a general term for polymers having a structure in which an ionic group is introduced into a hydrocarbon skeleton.

  Here, the perfluoro-based polymer means a polymer in which most or all (typically 90% or more) of alkyl group and / or alkylene group hydrogen in the polymer is substituted with fluorine atoms. Representative examples of perfluoro polymers having an ionic group include Nafion (registered trademark) (manufactured by DuPont), Flemion (registered trademark) (manufactured by Asahi Glass Co., Ltd.), and Aciplex (registered trademark) (manufactured by Asahi Kasei Co., Ltd.). A commercial item can be mentioned.

  A perfluoro-based polymer has a problem that it is very expensive and has a large gas crossover. In view of mechanical strength, physical durability, chemical stability, etc., the ionic group-containing polymer (A) is preferably a hydrocarbon-based polymer, and a hydrocarbon having an aromatic ring in the main chain. More preferably, it is a polymer. Here, the aromatic ring may include not only a hydrocarbon aromatic ring but also a hetero ring. Further, a part of the aliphatic units may constitute a polymer together with the aromatic ring unit.

  Specific examples of hydrocarbon polymers having an aromatic ring in the main chain include polysulfone, polyethersulfone, polyphenylene oxide, polyarylene ether, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, polyarylene ketone, polyether ketone, poly Examples thereof include polymers such as arylene phosphine oxide, polyether phosphine oxide, polybenzoxazole, polybenzthiazole, polybenzimidazole, aromatic polyamide, polyimide, polyetherimide, and polyimidesulfone.

  Of these, aromatic polyether polymers are preferred from the viewpoints of mechanical strength, physical durability, and production cost. Here, the aromatic polyether polymer is a general term for polymers having at least an aromatic ring and an ether bond in the main chain. In addition, it exhibits crystallinity due to good packing of the main chain skeleton structure and extremely strong intermolecular cohesion, has no property of dissolving in general solvents, and has excellent tensile strength and elongation, tear strength and fatigue resistance. Therefore, an aromatic polyether ketone polymer is particularly preferable. Here, the aromatic polyether ketone polymer is a general term for polymers having at least an aromatic ring, an ether bond and a ketone bond in the main chain, and includes an aromatic polyether ketone, an aromatic polyether ketone ketone, an aromatic Aromatic polyether ether ketone, aromatic polyether ether ketone ketone, aromatic polyether ketone ether ketone ketone, aromatic polyether ketone sulfone, aromatic polyether ketone phosphine oxide, aromatic polyether ketone nitrile and the like.

The ionic group of the ionic group-containing polymer (A) is preferably a negatively charged atomic group, and preferably has 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. Among them, it is more preferable to have at least a sulfonic acid group, a sulfonimide group or a sulfuric acid group from the viewpoint of high proton conductivity, and most preferable to have at least a sulfonic acid group from the viewpoint of raw material cost. The ionic group may form a salt. Examples of the cation that forms a salt with the ionic group 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 cations include cations such as Li, Na, K, Rh, Mg, Ca, Sr, Ti, Al, Fe, Pt, Rh, Ru, Ir, and Pd. Among them, Na, K, and Li cations that are inexpensive and can be easily proton-substituted are preferably used.

  The molecular weight of the ionic group-containing polymer (A) is preferably from 10,000 to 5,000,000, and more preferably from 10,000 to 500,000 in terms of polystyrene-converted weight average molecular weight. If it is less than 10,000, any of the mechanical strength, physical durability, and solvent resistance may be insufficient, such as cracking in the molded film. On the other hand, if it exceeds 5 million, the solubility becomes insufficient, the solution viscosity is high, and the processability may be poor.

  As the ionic group-containing polymer (A), a block having a segment (A1) containing an ionic group and a segment (A2) containing no ionic group in terms of proton conductivity and power generation characteristics under low humidification conditions More preferably, it is a copolymer. In addition, in this specification, although it describes for convenience as "the segment (A2) which does not contain an ionic group", the said segment (A2) has an ionic group in the range which does not have a decisive bad influence on the performance as an electrolyte membrane. It is not excluded that a small amount is contained. Further, a block copolymer having a linker site for connecting the segments is more preferable. Due to the presence of the linker, different segments can be linked while effectively suppressing side reactions.

  The number average molecular weight of the segment (A1) containing an ionic group and the segment (A2) containing no ionic group is related to the domain size of the phase separation structure at the time of molding the ionic group-containing polymer (A). From the balance between proton conductivity and physical durability under low humidification, each is preferably 55,000 or more, more preferably 10,000 or more, and most preferably 15,000 or more. Moreover, 50,000 or less is more preferable, More preferably, it is 40,000 or less, Most preferably, it is 30,000 or less.

  As such an ionic group-containing polymer (A), the segment (A1) containing an ionic group is represented by the following general formula (S1), and the segment (A2) containing no ionic group is represented by the following general formula (S2). What contains the structural unit represented by these is further more preferable.

(In the general formula (S1), Ar ^{1 to} Ar ⁴ represent any divalent arylene group, and at least one of Ar ¹ and Ar ² has an ionic group as a substituent. Ar ³ and Ar ⁴ may or may not have an ionic group as a substituent, Ar ^{1 to} Ar ⁴ may be optionally substituted with a group other than the ionic group, and Ar ^{1 to} Ar ⁴ are structural units. R may be the same as or different from each other, R represents a ketone group or a protecting group that can be derived from the ketone group, and may be the same or different from each other. Represents the binding site.)

(In the general formula (S2), Ar ^{5 to} Ar ⁸ represent any divalent arylene group and may be optionally substituted, but have no ionic group. Ar ^{5 to} Ar ⁸ are each a structural unit. R may represent a ketone group or a protecting group that can be derived from a ketone group, and may be the same or different from each other, and * may be the same as or different from the general formula (S2) or other structural units. Represents the binding site.)
Specific examples of the protecting group that can be derived from a ketone group include protecting groups that are generally used in organic synthesis, and represent a substituent that is temporarily introduced on the assumption that it is removed at a later stage, It can be returned to its original ketone group by deprotection.

  Such protecting groups include, for example, Theodora W. Greene, “Protective Groups in Organic Synthesis”, John Willy & Sons (USA), John Wiley & Sons (John Wily & Sons, USA). Inc), 1981, which can be preferably used.

In the block copolymer containing the structural unit represented by the above general formula, all the arylene groups are chemically stabilized with an electron-attracting ketone group, and further, toughening by imparting crystallinity, glass transition temperature. The physical durability is increased by the softening due to the decrease.

In the above general formulas (S1) and (S2), Ar ^{1 to} Ar ⁸ include hydrocarbon-based arylene groups such as a phenylene group, a naphthylene group, a biphenylene group, and a fluorenediyl group, pyridinediyl, quinoxalinediyl, and thiophenediyl. A heteroarylene group, preferably a phenylene group, and most preferably a p-phenylene group.

  The segment (A1) containing an ionic group is more preferably a structural unit that is chemically stable, has an increased acidity due to an electron withdrawing effect, and is introduced with an ionic group at a high density. The segment (A2) not containing an ionic group is more preferably a structural unit that is chemically stable and exhibits crystallinity due to strong intermolecular cohesion.

  The content of the structural unit represented by the general formula (S1) contained in the segment (A1) containing the ionic group is preferably 20 mol% or more, more preferably 50 mol% or more, and more preferably 80 mol% or more. Further preferred.

  The content of the structural unit represented by the general formula (S2) contained in the segment (A2) not containing an ionic group is preferably 20 mol% or more, more preferably 50 mol% or more, and more preferably 80 mol% or more. Further preferred. When the content of the general formula (S2) contained in the segment (A2) not containing an ionic group is less than 20 mol%, mechanical strength, dimensional stability, and physical durability due to crystallinity are lowered. Tend.

  More preferred specific examples of the structural unit represented by the general formula (S1) include structural units represented by the following general formula (P2) in terms of raw material availability. Among these, from the viewpoint of raw material availability and polymerizability, a structural unit represented by the following formula (P3) is more preferable, and a structural unit represented by the following formula (P4) is most preferable.

(In formulas (P2), (P3), and (P4), M ^{1 to} M ⁴ represent hydrogen, a metal cation, and an ammonium cation NR ₄ ⁺ (R is an arbitrary organic group), and M ^{1 to} M ⁴ are 2 In addition, r1 to r4 each independently represents an integer of 0 to 2, r1 + r2 represents an integer of 1 to 8, and r1 to r4 may be different for each structural unit. R represents a ketone group or a protecting group that can be derived from a ketone group, and may be the same or different from each other, and * represents a binding site with the formula (P2), (P3), (P4), or other structural unit. Represents.)
The molar composition ratio (A1 / A2) of the segment (A1) containing an ionic group and the segment (A2) not containing an ionic group is more preferably 0.2 or more, and more preferably 0.33 or more. 0.5 or more is most preferable. Moreover, 5 or less is more preferable, 3 or less is more preferable, and 2 or less is the most preferable. When the molar composition ratio A1 / A2 is less than 0.2 or exceeds 5, the proton conductivity under low humidification conditions tends to be insufficient, or the hot water resistance and physical durability tend to be insufficient. .

  The ion exchange capacity of the segment (A1) containing an ionic group is preferably 2.5 meq / g or more, more preferably 3 meq / g or more, and still more preferably from the viewpoint of proton conductivity under low humidification conditions. It is 3.5 meq / g or more. Moreover, 6.5 meq / g or less is preferable from the point of hot water resistance or physical durability, 5 meq / g or less is more preferable, and 4.5 meq / g or less is further more preferable.

  The ion exchange capacity of the segment (A2) not containing an ionic group is preferably low from the viewpoint of hot water resistance, mechanical strength, dimensional stability, and physical durability, preferably 1 meq / g or less, more preferably 0. 0.5 meq / g or less, more preferably 0.1 meq / g or less.

  When the ionic group is a sulfonic acid group, the ion exchange capacity is preferably 0.1 to 5 meq / g, more preferably 1.5 meq / g or more, further preferably, from the viewpoint of the balance between proton conductivity and water resistance. Is 2 meq / g or more. Moreover, 3.5 meq / g or less is more preferable, More 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, hot water resistance may be insufficient.

  As a block copolymer used as the ionic group-containing polymer (A), a phase separation structure is observed when the molded body is observed with a transmission electron microscope (TEM) at a magnification of 50,000 times, and an average interlayer measured by image processing is used. The distance or the average interparticle distance is preferably 5 nm or more and 500 nm or less. Among them, the average interlaminar distance or the average interparticle distance is more preferably 10 nm or more and 50 nm or less, and more preferably 15 nm or more and 30 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 5 nm, the continuity of the ion channel may be insufficient and the conductivity may be insufficient. Further, when the interlayer distance exceeds 500 nm, the mechanical strength and dimensional stability may be poor.

  The block copolymer used as the ionic group-containing polymer (A) preferably has crystallinity. That is, it is preferable that crystallinity is recognized by differential scanning calorimetry (DSC) or wide-angle X-ray diffraction. Specifically, the crystallization calorific value measured by differential scanning calorimetry is 0.1 J / g or more, or The crystallinity measured by wide angle X-ray diffraction is preferably 0.5% or more. Note that “having crystallinity” means that the polymer can be crystallized when the temperature is raised, has a crystallizable property, or has already been crystallized. An amorphous polymer means a polymer that is not a crystalline polymer and that does not substantially proceed with crystallization. Therefore, even if it is a crystalline polymer, if the crystallization is not sufficiently advanced, the polymer may be in an amorphous state.

[Polymer electrolyte composition]
The polymer electrolyte composition of the present invention is particularly suitably used as a molded polymer electrolyte. The polymer electrolyte molded body may be in various forms depending on the intended use, such as a plate shape, a fiber shape, a hollow fiber shape, a particle shape, a lump shape, a microporous shape, and a foam shape in addition to a membrane shape. In particular, after forming a membrane-shaped polymer electrolyte molded body (polymer electrolyte membrane), an electrolyte membrane with a catalyst layer, a membrane electrode assembly, a polymer electrolyte fuel cell, an electrochemical hydrogen pump, and a water electrolysis hydrogen It is optimal for use as a member of a generator.

  There is no particular limitation on the method for forming the polymer electrolyte membrane, but a method of forming a polymer electrolyte composition in a solution state, a method of forming a polymer electrolyte composition in a molten state, or the like is possible. In the former, for example, the ionic group-containing polymer (A) and the phosphorus-containing polymer (B) are dissolved in a solvent such as N-methyl-2-pyrrolidone, and the solution is cast on a glass plate or the like, A method of forming a film by removing the solvent can be exemplified.

  The solvent used for film formation is not particularly limited as long as it can dissolve the ionic group-containing polymer (A) and the phosphorus-containing polymer (B) and then remove them. For example, N, N-dimethylacetamide, N, N -Aprotic polar solvents such as dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphontriamide, esters such as γ-butyrolactone, butyl acetate Solvents, carbonate solvents such as ethylene carbonate and propylene carbonate, alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether and propylene glycol monoethyl ether Le or an alcohol-based solvent such as isopropanol,, water and mixtures thereof is preferably used, it is preferred for high highest solubility aprotic polar solvent. In order to enhance the solubility of the segment (A1) containing an ionic group, it is also preferable to add a crown ether such as 18-crown-6.

  It is a preferable method for obtaining a tough film to remove a foreign substance by subjecting the polymer electrolyte composition of a solution prepared to a required solid content concentration to normal pressure filtration or pressure filtration. The filter medium used here is not particularly limited, but a glass filter or a metallic filter is suitable.

  The film thickness of the polymer electrolyte membrane 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, additives such as crystallization nucleating agents, plasticizers, stabilizers, antioxidants or mold release agents used in ordinary polymer compounds are not contrary to the object of the present invention in the polymer electrolyte composition. Further additions can be made within the range.

  Furthermore, for the purpose of improving mechanical strength, thermal stability, processability, etc., the polymer electrolyte composition is composed of polymers, elastomers, fillers, fine particles other than ionic group-containing polymer (A) and phosphorus-containing polymer (B). Various additives may be included. Moreover, you may reinforce with a microporous film, a nonwoven fabric, a mesh, etc.

  The polymer electrolyte composition 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. The polymer electrolyte molded body of the present invention can be preferably used for various electrochemical applications. Examples of electrochemical applications include solid polymer fuel cells, redox flow batteries, water electrolyzers, chloroalkali electrolyzers, electrochemical hydrogen pumps, and water electrolyzed hydrogen generators. It can be particularly preferably used for batteries, electrochemical hydrogen pumps, and water electrolysis hydrogen generators.

  When the polymer electrolyte composition of the present invention is used for a polymer electrolyte fuel cell, a polymer electrolyte membrane and a binder for an electrode catalyst layer are preferred, and among them, the polymer electrolyte membrane is particularly suitably used.

  The polymer electrolyte fuel cell has a structure in which a catalyst layer, an electrode base material, and a separator are sequentially laminated on both surfaces of a polymer electrolyte membrane. Of these, the one in which the catalyst layers are laminated on both sides of the polymer electrolyte membrane (that is, the layer configuration of catalyst layer / electrolyte membrane / catalyst layer) is called an electrolyte membrane with a catalyst layer (CCM). An electrode-electrolyte membrane assembly is obtained by sequentially laminating a catalyst layer and a gas diffusion substrate on both sides (that is, a gas diffusion substrate / catalyst layer / electrolyte membrane / catalyst layer / gas diffusion substrate layer structure). Or it is called a membrane electrode assembly (MEA).

  As a method for producing CCM, a coating method in which a catalyst layer paste composition for forming a catalyst layer is applied and dried on the electrolyte membrane surface is generally performed.

  When a membrane electrode assembly (MEA) is produced by pressing, a known method (for example, the chemical plating method described in Electrochemistry, 1985, 53, p. 269, edited by Electrochemical Society (J. Electrochem. Soc. , Electrochemical Science and Technology (1988, 135, 9, p. 2209., etc.), and the like. The temperature and pressure during pressing 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 roll presses and double belt presses that specify pressure and clearance, flat plate presses that specify pressure, etc., such as industrial productivity and thermal decomposition suppression of polymer materials having ionic groups. From the viewpoint, it is preferably carried out in the range of 0 to 250 ° C. 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 an electrode and an electrolyte membrane are stacked without performing a composite by a pressing process. It is one of the preferable options from the viewpoint of preventing short-circuiting of the anode and the cathode electrode. 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.

  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) Ion exchange capacity (IEC)
It measured by the neutralization titration method as described in the following (i)-(iv). The measurement was performed 3 times and the average value was taken.
(I) Moisture on the membrane surface of the electrolyte membrane that had been proton-substituted and thoroughly washed with pure water was wiped off, and then vacuum-dried at 100 ° C. for 12 hours or more to determine the dry weight.
(Ii) 50 mL of a 5 wt% aqueous sodium sulfate solution was added to the electrolyte, and the mixture was allowed to stand for 12 hours for ion exchange.
(Iii) The generated sulfuric acid was titrated using 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 light reddish purple was obtained was taken as the end point.
(Iv) The ion exchange capacity was determined by the following equation.
Ion exchange capacity (meq / g) =
[Concentration of sodium hydroxide aqueous solution (mmol / mL) × Drip amount (mL)] / Dry weight of sample (g)]
(2) Proton conductivity (H conductivity)
After immersing the membranous sample in pure water at 25 ° C. for 24 hours, it is kept in a constant temperature and humidity chamber at 80 ° C. and a relative humidity of 25 to 95% for 30 minutes at each step, and proton conduction is performed by a constant potential AC impedance method. 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 a 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 sheets) was used. The electrodes were arranged at a distance of 10 mm between the front and back sides of the sample film so as to be parallel to each other and perpendicular 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 HLC-8022GPC is used as an integrated UV detector and differential refractometer, and Tosoh TSK gel SuperHM-H (inner diameter 6.0 mm, length 15 cm) is used as the GPC column. -2-pyrrolidone solvent (N-methyl-2-pyrrolidone solvent containing 10 mmol / L of lithium bromide) was measured 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 by polystyrene conversion.

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

(5) Measuring method of purity It analyzed quantitatively by the gas chromatography (GC) of the following conditions.
Column: DB-5 (manufactured by J & W) L = 30 m Φ = 0.53 mm D = 1.50 μm
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 ° C / min
Final; 300 ° C x 15 min
SP ratio; 50: 1
(6) Additive amount measurement of additive The additive amount of the electrolyte membrane was evaluated by inductively coupled plasma (ICP) emission analysis. The electrolyte membrane was cut out in a size of 5 cm × 5 cm, dried at 110 ° C. under reduced pressure for 2 hours, accurately weighed, and allowed to stand at 550 ° C. for 2 days. To obtain a liquid in which the additive was completely extracted. This solution was measured by ICP emission analysis, and the amount of phosphorus and various metal elements was measured to quantitate the additive.

(7) Hot water resistance of the additive The hot water resistance of the additive was evaluated by measuring the residual rate after immersion in hot water at 95 ° C. The electrolyte membrane was cut into two strips having a length of about 5 cm and a width of about 10 cm, and the additive was eluted by immersing it in hot water at 95 ° C. for 8 hours. The electrolyte membrane before and after immersion in hot water was cut out in a size of 5 cm × 5 cm, the ICP emission analysis was performed to measure the additive content, and the hot water resistance was evaluated as the additive residual rate.

(8) Nuclear magnetic resonance spectrum (NMR)
Under the following measurement conditions, ¹ H-NMR was measured to confirm the structure and to determine the molar composition ratio of the segment (A1) containing an ionic group and the segment (A2) containing no ionic group. The molar composition ratio is 8.2 ppm (derived from disulfonate-4,4′-difluorobenzophenone) and 6.5 to 8.0 ppm (derived from all aromatic protons excluding disulfonate-4,4′-difluorobenzophenone). It was calculated from the integrated value of the recognized peak.

Apparatus: EX-270 manufactured by JEOL Ltd.
Resonance frequency: 270 MHz ( ¹ H-NMR)
Measurement temperature: room temperature Dissolving solvent: DMSO-d6
Internal reference material: TMS (0 ppm)
Number of integrations: 16 times (9) Chemical stability (A) Molecular weight retention rate For electrolyte membranes soluble in N-methylpyrrolidone (NMP), the electrolyte membrane is degraded by the following method, and the molecular weight before and after the degradation test Were compared to evaluate chemical stability.

Prepare a pair of commercially available electrodes, gas diffusion electrode for fuel cell “ELAT (registered trademark) LT120ENSI” 5 g / m ² Pt cut into 5 cm square by BASF, and sandwich the electrolyte membrane as a fuel electrode and an oxidation electrode The membrane electrode assembly for evaluation was obtained by heating and pressing at 150 ° C. and 5 MPa for 3 minutes.

This membrane / electrode assembly was set in a JARI standard cell “Ex-1” (electrode area 25 cm ² ) manufactured by Eiwa Co., Ltd., and kept at 80 ° C. while maintaining low humidity in hydrogen (70 mL / min, back pressure 0.1 MPaG). ) And air (174 mL / min, back pressure 0.05 MPaG) were introduced into the cell, and an accelerated deterioration test was performed in an open circuit. After operating the fuel cell under these conditions for 200 hours, the membrane-electrode assembly was taken out, put into a mixed solution of ethanol / water, and further subjected to ultrasonic treatment to remove the catalyst layer. Then, the molecular weight of the remaining polymer electrolyte membrane was measured and evaluated as a molecular weight retention rate.

(B) Open Circuit Holding Time For an electrolyte membrane that cannot be dissolved in NMP, the chemical stability was evaluated by degrading the electrolyte membrane by the following method and comparing the holding time of the open circuit voltage.

  A membrane electrode assembly was prepared by the same method as described above, and set in an evaluation cell. Subsequently, a deterioration acceleration test in an open circuit was performed under the same conditions as described above. The time until the open circuit voltage decreased to 0.7 V or less was evaluated as the open circuit holding time.

(C) Voltage holding ratio Even if the open circuit holding time evaluation of (B) above is performed, if the voltage can be maintained for 3000 hours or more and 0.7 V or more, the evaluation is stopped and the initial voltage is compared with the voltage after 3000 hours Chemical durability was evaluated as a voltage holding ratio.

[Synthesis Example 1] Synthesis of block copolymer b1 (Synthesis of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane (K-DHBP) represented by the following general formula (G1))

  In a 500 mL flask equipped with a stirrer, thermometer and distillation tube, 49.5 g of 4,4′-dihydroxybenzophenone (DHBP), 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate and p-toluenesulfonic acid monohydrate Charge 0.50 g and dissolve. Thereafter, the mixture was stirred 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, and 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 of disodium 3,3'-disulfonate-4,4'-difluorobenzophenone represented by the following general formula (G2))

109.1 g (Aldrich Reagent) of 4,4′-difluorobenzophenone was reacted at 150 ° C. for 10 hours in 150 mL of fuming sulfuric acid (50% SO 3) (Wako Pure Chemical 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).

  (Synthesis of an oligomer containing no ionic group represented by the following general formula (G3))

(In the formula (G3), m represents a positive integer.)
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.8 g (100 mmol) of K-DHBP, and 4,4′-difluorobenzophenone 20. 3 g (Aldrich reagent, 93 mmol) was added, and after nitrogen substitution, dehydration was performed at 160 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, followed by temperature rise to remove toluene, and polymerization was performed at 180 ° C. for 1 hour. . Purification was performed by reprecipitation with a large amount of methanol to obtain an oligomer containing no ionic group (terminal OM group, where M in the OM group represents Na or K, and the following notation follows this). . The number average molecular weight was 10,000.

  A 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap was charged with 1.1 g of potassium carbonate (Aldrich reagent, 8 mmol) and 20.0 g (2 mmol) of the oligomer (terminal OM group). Then, after dehydrating at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, the temperature was raised to remove cyclohexane, and 4.0 g (Aldrich reagent, 12 mmol) of decafluorobiphenyl was added, and 105 ° C. for 1 hour. Reaction was performed. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a1 '(terminal fluoro group) containing no ionic group represented by the formula (G3). 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 an oligomer containing an ionic group represented by the following general formula (G4))

(In the formula (G4), M represents Na or K.)
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 12.9 g (50 mmol) of the K-DHBP, and 4,4′-biphenol 9. 3 g (Aldrich reagent, 50 mmol), disodium 3,3′-disulfonate-4,4′-difluorobenzophenone 40.6 g (96 mmol), and 18-crown-6 ether 17.9 g (Wako Pure Chemical, 82 mmol) After nitrogen substitution, dehydration was performed at 170 ° 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 180 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a2 ′ (terminal OM group) containing an ionic group represented by the formula (G4). The number average molecular weight was 29000.

(Polyketal ketone using an oligomer represented by the general formula (G4) as a segment (A1) containing an ionic group and an oligomer represented by the general formula (G3) as a segment (A2) not containing an ionic group) (Synthesis of (PKK) block copolymer b1)
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 29 g (1 mmol) of an oligomer a2 ′ (terminal OM group) containing an ionic group After substitution with nitrogen, dehydration was performed at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, and the temperature was increased to remove cyclohexane, and 11 g of an oligomer a1 ′ (terminal fluoro group) containing no ionic group (1 mmol) was added and reacted at 105 ° C. for 24 hours. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain a block copolymer b1. The weight average molecular weight was 400,000.

  The segment (A1) containing an ionic group of the block copolymer b1 contains 50 mol% of the structural unit represented by the general formula (S1), and the segment (A2) containing no ionic group contains the general formula (S2). ) Was included at 100 mol%.

When only the block copolymer b1 was formed into a polymer electrolyte membrane, the ion exchange capacity determined from neutralization titration was 2.3 meq / g, and the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 58 mol. / 42 mol = 1.38.

[Synthesis Example 2] Synthesis of Block Copolymer b2 (Synthesis of Polyethersulfone (PES) Block Copolymer Precursor b2 ′ Consisting of Segment Represented by Formula (G6) and Segment Represented by Formula (G7))
1.78 g of anhydrous nickel chloride and 15 mL of dimethyl sulfoxide were mixed and adjusted to 70 ° C. 2,2'-bipyridyl 2.37g was added to this, and it stirred at the same temperature for 10 minutes, and prepared the nickel containing solution.

  Here, 1.64 g of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl) and polyethersulfone represented by the following formula (G5) (Sumitomo Chemical Sumika Excel PES5200P, Mn = 40,000, Mw = 94,000) 0.55 g was dissolved in 5 mL of dimethyl sulfoxide, and 1.35 g of zinc powder was added to adjust to 70 ° C. The nickel-containing solution was poured into this, and a polymerization reaction was performed at 70 ° C. for 4 hours. The reaction mixture was added to 60 mL of methanol, and then 60 mL of 6 mol / L hydrochloric acid was added and stirred for 1 hour. The precipitated solid was separated by filtration and dried to obtain 1.75 g of a block copolymer precursor b2 ′ (polyarylene precursor) containing a gray-white segment represented by the following formula (G6) and the following formula (G7). Obtained at 97%. The weight average molecular weight was 210,000.

(Synthesis of polyethersulfone (PES) block copolymer b2 comprising the segment represented by the formula (G7) and the segment represented by the following formula (G8))
0.25 g of block copolymer precursor b2 ′ was added to a mixed solution of 0.18 g of lithium bromide monohydrate and 8 mL of N-methyl-2-pyrrolidone, and reacted at 120 ° C. for 24 hours. The reaction mixture was poured into 80 mL of 6 mol / L hydrochloric acid and stirred for 1 hour. The precipitated solid was separated by filtration. The separated solid was dried to obtain a block copolymer b2 composed of a gray-white segment represented by the formula (G7) and a segment represented by the following formula (G8).

  The obtained block copolymer b2 had a weight average molecular weight of 190,000. When only the block copolymer b2 was molded into a polymer electrolyte membrane, the ion exchange capacity determined from neutralization titration was 2.02 meq / g.

[Synthesis Example 3] Synthesis of block copolymer b3 (Synthesis of hydrophobic oligomer represented by the following formula (G9))

  Into a 1 L three-necked flask equipped with a stirrer, thermometer, condenser, Dean-Stark tube, and nitrogen-introduced three-way cock, 51.9 g (0.30 mol) of 2,6-dichlorobenzonitrile, 2,2-bis ( 4-Hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane 92.8 g (0.27 mol) and potassium carbonate 49.7 g (0.36 mol) were weighed.

  After substitution with nitrogen, 363 mL of sulfolane and 181 mL of toluene were added and stirred. The flask was placed in an oil bath and heated to reflux at 150 ° C. When water produced by the reaction was azeotroped with toluene and reacted while being removed from the system with a Dean-Stark tube, almost no water was observed in about 3 hours. After removing most of the toluene while gradually raising the reaction temperature, the reaction was continued at 200 ° C. for 3 hours. Next, 12.9 g (0.076 mol) of 2,6-dichlorobenzonitrile was added and reacted for another 5 hours.

  The resulting reaction solution was allowed to cool and then diluted by adding 100 mL of toluene. The precipitate of the inorganic compound produced as a by-product was removed by filtration, and the filtrate was put into 2 L of methanol. The precipitated product was separated by filtration, collected, dried, and then dissolved in 250 mL of tetrahydrofuran. This was reprecipitated in 2 L of methanol to obtain 109 g of the target oligomer. The number average molecular weight of the oligomer was 8,000.

  (Synthesis of hydrophilic monomer represented by the following formula (G10))

  To a 3 L three-necked flask equipped with a stirrer and a condenser, 245 g (2.1 mol) of chlorosulfonic acid was added, followed by 105 g (420 mmol) of 2,5-dichlorobenzophenone, and allowed to react in an oil bath at 100 ° C. for 8 hours. It was. After a predetermined time, the reaction solution was slowly poured onto 1000 g of crushed ice and extracted with ethyl acetate. The organic layer was washed with brine and dried over magnesium sulfate, and then ethyl acetate was distilled off to obtain pale yellow crude crystals of 3- (2,5-dichlorobenzoyl) benzenesulfonic acid chloride. The crude crystals were not purified and used as they were in the next step.

  41.1 g (462 mmol) of 2,2-dimethyl-1-propanol (neopentyl alcohol) was added to 300 mL of pyridine and cooled to about 10 ° C. The crude crystals obtained above were gradually added thereto over about 30 minutes. After the total amount was added, the reaction was further stirred for 30 minutes. After the reaction, the reaction solution was poured into 1000 mL of hydrochloric acid water, and the precipitated solid was collected. The obtained solid was dissolved in ethyl acetate, washed with aqueous sodium hydrogen carbonate solution and brine, dried over magnesium sulfate, and then ethyl acetate was distilled off to obtain crude crystals. This was recrystallized with methanol to obtain white crystals of neopentyl 3- (2,5-dichlorobenzoyl) benzenesulfonate represented by the above structural formula.

  (Synthesis of polyarylene block copolymer b3 represented by the following formula (G11))

  To a 1 L three-necked flask connected with a stirrer, a thermometer, and a nitrogen introduction tube, 166 mL of dried N, N-dimethylacetamide (DMAc) was added to 15.1 g (1.89 mmol) of the aforementioned hydrophobic oligomer, 3- ( 2,5-dichlorobenzoyl) benzenesulfonate neopentyl 39.5 g (98.4 mmol), bis (triphenylphosphine) nickel dichloride 2.75 g (4.2 mmol), triphenylphosphine 11.0 g (42.1 mmol), iodine To a mixture of sodium bromide 0.47 g (3.15 mmol) and zinc 16.5 g (253 mmol) was added under nitrogen.

  The reaction system was heated with stirring (finally heated to 82 ° C.) and allowed to react for 3 hours. An increase in viscosity in the system was observed during the reaction. The polymerization reaction solution was diluted with 180 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid. Add 35.6 g (295 mmol) of lithium bromide to the filtrate in 1/3 portions at 1 hour intervals and add 1 hour intervals at a 1 L three-neck equipped with a stirrer at 120 ° C. for 5 hours under a nitrogen atmosphere. Reacted. After the reaction, the mixture was cooled to room temperature, poured into 4 L of acetone and solidified. The coagulum was collected by filtration, air-dried, pulverized with a mixer, and washed with 1500 mL of 1N sulfuric acid while stirring. After filtration, the product was washed with ion-exchanged water until the pH of the washing solution reached 5 or higher, and then dried at 80 ° C. overnight to obtain 39.1 g of the target block copolymer b3. The weight average molecular weight of this block copolymer was 200,000.

  When the block copolymer b3 itself was used as a polymer electrolyte membrane, the ion exchange capacity determined from neutralization titration was 2.3 meq / g.

[Synthesis Example 4] Synthesis of phosphorus-containing polymer HQPEP (Synthesis of phosphorus-containing polymer represented by the following formula (G12))

  Using 160 g of potassium carbonate, 11 g (0.10 mol) of hydroquinone, and 30 g (0.10 mol) of bis (4-fluorophenyl) phenylphosphine in 620 mL of N-methylpyrrolidone (NMP) at 160 ° C. The polymerization reaction was performed for 2 hours. Purification was performed by sequentially reprecipitation with a large amount of water and methanol to obtain a phosphorus-containing polymer (HQPEP). The number average molecular weight of the obtained HQPEP was 80,000.

[Synthesis Example 5] Synthesis of phosphorus-containing polymer HQPESP (Synthesis of phosphorus-containing polymer represented by the following formula (G13))

  Polymerization was carried out by the method described in Synthesis Example 4, except that 30 g of bis (4-fluorophenyl) phenylphosphine was changed to 42 g (0.10 mol) of potassium 4- (bis (4-fluorophenyl) phosphanyl) benzenesulfonic acid. And a phosphorus-containing polymer (HQPESP) was obtained. The number average molecular weight of the obtained HQPESP was 90,000.

[Synthesis Example 6] Synthesis of phosphorus-containing polymer HQPEMP (Synthesis of phosphorus-containing polymer represented by the following formula (G14))

  Polymerization was performed by the method described in Synthesis Example 4 except that 30 g of bis (4-fluorophenyl) phenylphosphine was changed to 24 g (0.10 mol) of bis (4-fluorophenyl) methylphosphine, and a phosphorus-containing polymer (HQPMP ) The number average molecular weight of the obtained HQPEMP was 65,000.

[Synthesis Example 7] Synthesis of phosphorus-containing polymer HQPEPO (Synthesis of phosphorus-containing polymer represented by the following formula (G15))

  Polymerization was performed by the method described in Synthesis Example 4 except that 30 g of bis (4-fluorophenyl) phenylphosphine was changed to 31 g (0.10 mol) of bis (4-fluorophenyl) phenylphosphine oxide, and a phosphorus-containing polymer ( HQPEPO) was obtained. The number average molecular weight of the obtained HQPEPO was 100,000.

[Synthesis Example 8] Synthesis of phosphorus-containing polymer HQPEMPO (Synthesis of phosphorus-containing polymer represented by the following formula (G16))

  Polymerization was carried out by the method described in Synthesis Example 4 except that 30 g of bis (4-fluorophenyl) phenylphosphine was changed to 25 g (0.10 mol) of bis (4-fluorophenyl) methylphosphine oxide, and a phosphorus-containing polymer ( HQPEMPO) was obtained. The number average molecular weight of the obtained HQPEMPO was 85,000.

[Synthesis Example 9] Synthesis of phosphorus-containing polymer HQPEPP (Synthesis of phosphorus-containing polymer represented by the following formula (G17))

  Using potassium carbonate 17 g (0.12 mol), hydroquinone 11 g (0.10 mol), and bis (4-fluorophenyl) phenyl phosphate 36 g (0.10 mol) in N-methylpyrrolidone (NMP) 620 mL at 100 ° C. The polymerization reaction was performed for 6 hours. Purification was performed by sequentially reprecipitation with a large amount of water and methanol to obtain a phosphorus-containing polymer (HQPEPP). The number average molecular weight of the obtained HQPEPP was 50,000.

[Example 1]
20 g of the block copolymer b1 obtained in Synthesis Example 1 was dissolved in 80 g of NMP. To this solution, 200 mg of HQPEP obtained in Synthesis Example 4 was added, and stirred at 20,000 rpm for 3 minutes with a stirrer to obtain a transparent solution having a polymer concentration of 20% by mass. The solubility of the polymer was very good. The obtained solution was subjected to pressure filtration using a glass fiber filter, cast onto a glass substrate, dried at 100 ° C. for 4 hours, and then heat-treated at 150 ° C. for 10 minutes under nitrogen to produce a polyketal ketone membrane ( A film thickness of 15 μm) was obtained. After immersing in a 10% by weight sulfuric acid aqueous solution at 95 ° C. for 24 hours to carry out proton substitution and deprotection reactions, they were immersed in a large excess amount of pure water for 24 hours and thoroughly washed.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate was not measurable, the open circuit retention time was measured as a durability test, but the evaluation was not completed within 3000 hours. The chemical durability of the electrolyte membrane was evaluated. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 2]
An electrolyte membrane was obtained in the same manner as in Example 1 except that HQPEP was changed to 1 g.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate was not measurable, the open circuit retention time was measured as a durability test, but the evaluation was not completed within 3000 hours. The chemical durability of the electrolyte membrane was evaluated. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 3]
An electrolyte membrane was obtained in the same manner as in Example 1 except that HQPEP was changed to 20 mg.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate could not be measured, the open circuit retention time was measured as a durability test. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 4]
An electrolyte membrane was obtained in the same manner as in Example 1 except that the PES block copolymer b2 was used instead of the block copolymer b1.

  Since the obtained film was soluble in NMP, the molecular weight retention rate was measured as a durability test. Separately, ion exchange capacity and proton conductivity at 80 ° C. and 25% relative humidity were measured. The results are shown in Table 1.

[Example 5]
An electrolyte membrane was obtained in the same manner as in Example 1 except that the block copolymer b3 was used instead of the block copolymer b1.

  Since the obtained film was soluble in NMP, the molecular weight retention rate was measured as a durability test. Separately, ion exchange capacity and proton conductivity at 80 ° C. and 25% relative humidity were measured. The results are shown in Table 1.

[Example 6]
An electrolyte membrane was obtained in the same manner as in Example 1 except that Nafion (registered trademark) NRE211CS, which is a fluorine-based electrolyte, was used instead of the block copolymer b1.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate could not be measured, the open circuit retention time was measured as a durability test. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 7]
An electrolyte membrane was obtained in the same manner as in Example 1 except that 200 mg of HQPESP obtained in Synthesis Example 5 was used instead of HQPEP.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate was not measurable, the open circuit retention time was measured as a durability test, but the evaluation was not completed within 3000 hours. The chemical durability of the electrolyte membrane was evaluated. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 8]
An electrolyte membrane was obtained in the same manner as in Example 1 except that 200 mg of HQPMP obtained in Synthesis Example 6 was used instead of HQPEP.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate was not measurable, the open circuit retention time was measured as a durability test, but the evaluation was not completed within 3000 hours. The chemical durability of the electrolyte membrane was evaluated. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 9]
An electrolyte membrane was obtained in the same manner as in Example 1 except that 200 mg of HQPEPO obtained in Synthesis Example 7 was used instead of HQPEP.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate was not measurable, the open circuit retention time was measured as a durability test, but the evaluation was not completed within 3000 hours. The chemical durability of the electrolyte membrane was evaluated. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 10]
An electrolyte membrane was obtained in the same manner as in Example 1 except that 200 mg of HQPEMPO obtained in Synthesis Example 8 was used instead of HQPEP.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate was not measurable, the open circuit retention time was measured as a durability test, but the evaluation was not completed within 3000 hours. The chemical durability of the electrolyte membrane was evaluated. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 11]
An electrolyte membrane was obtained in the same manner as in Example 1 except that 200 mg of poly (bis (phenoxy) phosphazene) (Sigma Aldrich reagent) was used instead of HQPEP.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate could not be measured, the open circuit retention time was measured as a durability test. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 12]
An electrolyte membrane was obtained in the same manner as in Example 1 except that 200 mg of HQPEP obtained in Synthesis Example 9 was used instead of HQPEP.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate could not be measured, the open circuit retention time was measured as a durability test. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Example 13]
20 g of the electrolyte membrane obtained in Example 1 was further immersed in a 30 L aqueous solution in which 54 mg (0.125 mmol) of cerium nitrate hexahydrate was dissolved in pure water for 72 hours to incorporate cerium nitrate into the polymer electrolyte membrane. Got.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate was not measurable, the open circuit retention time was measured as a durability test, but the evaluation was not completed within 3000 hours. The chemical durability of the electrolyte membrane was evaluated. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Comparative Example 1]
An electrolyte membrane was obtained in the same manner as in Example 1 except that HQPEP was not added.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate could not be measured, the open circuit retention time was measured as a durability test. In addition, the ion exchange capacity and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

[Comparative Example 2]
An electrolyte membrane was obtained in the same manner as in Example 4 except that HQPEP was not added.

  Since the obtained film was soluble in NMP, the molecular weight retention rate was measured as a durability test. Separately, ion exchange capacity and proton conductivity at 80 ° C. and 25% relative humidity were measured. The results are shown in Table 1.

[Comparative Example 3]
An electrolyte membrane was obtained in the same manner as in Example 5 except that HQPEP was not added.

  Since the obtained film was soluble in NMP, the molecular weight retention rate was measured as a durability test. Separately, ion exchange capacity and proton conductivity at 80 ° C. and 25% relative humidity were measured. The results are shown in Table 1.

[Comparative Example 4]
An electrolyte membrane was obtained in the same manner as in Example 6 except that HQPEP was not added.

  Since the obtained film was insoluble in NMP and the molecular weight retention rate could not be measured, the open circuit retention time was measured as a durability test. In addition, the ion exchange capacity, hot water resistance, and proton conductivity at 80 ° C. and 25% relative humidity of the obtained electrolyte membrane were measured. The results are shown in Table 1.

Claims (18)

A polymer electrolyte composition comprising an ionic group-containing polymer (A) and a phosphorus-containing polymer (B) comprising a structure selected from the group consisting of the following general formulas (C1), (C2) and (C3).

(In the formula, R ₁ represents an arbitrary divalent organic group, R ₂ represents an arbitrary monovalent organic group. R _{1 to} R ₂ may be arbitrarily bonded to form a ring structure. A plurality of R ₁ and R ₂ in the polymer chain may be the same or different.)   The polymer electrolyte composition according to claim 1, wherein the phosphorus-containing polymer (B) is a polymer having a carbon-phosphorus-carbon bond in the main chain. The polymer electrolyte composition according to claim 1 or 2, wherein the organic group R ₁ or R _{2 in the} phosphorus-containing polymer (B) does not contain an ionic group. The phosphorus-containing organic group R ₁ in the polymer (B) is an aromatic hydrocarbon group, the polymer electrolyte composition according to any one of claims 1 to 3. The phosphorus-containing organic group R ₂ in the polymer (B) is an aromatic hydrocarbon group, the polymer electrolyte composition according to any one of claims 1 to 4.   The polymer electrolyte composition according to any one of claims 1 to 5, wherein the phosphorus-containing polymer (B) has a number average molecular weight of 2,000 or more and 1,000,000 or less.   The polymer electrolyte composition according to any one of claims 1 to 6, wherein a weight ratio of phosphorus to all elements contained in the phosphorus-containing polymer (B) is 0.01% or more and 30% or less.   The polymer according to any one of claims 1 to 7, wherein a content of the phosphorus-containing polymer (B) is 0.02 wt% or more and 10 wt% or less with respect to the ionic group-containing polymer (A). Electrolyte composition.   The alloy further comprises at least one transition metal selected from Ce, Mn, Ti, Zr, V, Cr, Mo, W, Ru, Co, Rh, Ir, Ni, Pd, Pt, Ag, and Au. The polymer electrolyte composition according to any one of -8.   The ionic group-containing polymer (A) is a block copolymer having a segment (A1) containing an ionic group and a segment (A2) containing no ionic group. Polymer electrolyte composition. The segment (A1) containing the ionic group and the segment (A2) not containing the ionic group contain structural units represented by the following general formulas (S1) and (S2), respectively. The polymer electrolyte composition according to claim 10.

(In the general formula (S1), Ar ^{1 to} Ar ⁴ represent any divalent arylene group, Ar ¹ and / or Ar ² contain an ionic group, and Ar ³ and Ar ⁴ contain an ionic group Ar ^{1 to} Ar ⁴ may be optionally substituted, and two or more types of arylene groups may be used independently of each other, and * represents the general formula (S1) or It represents the binding site with other structural units.)

(In the general formula (S2), Ar ^{5 to} Ar ⁸ represent an arbitrary divalent arylene group and may be optionally substituted, but do not contain an ionic group. Ar ^{5 to} Ar ⁸ are independent of each other. Two or more types of arylene groups may be used, and * represents a binding site with the general formula (S2) or other structural unit.)   The polymer electrolyte composition according to any one of claims 1 to 11, wherein the ionic group-containing polymer (A) is a hydrocarbon polymer having an aromatic ring in the main chain.   The polymer electrolyte membrane which consists of a polymer electrolyte composition in any one of Claims 1-12 shape | molded by the film form.   The electrolyte membrane with a catalyst layer formed by laminating | stacking a catalyst layer on both surfaces of the polymer electrolyte membrane of Claim 13.   A membrane electrode assembly comprising the polymer electrolyte membrane according to claim 13 in a solid polymer form.   A solid polymer fuel cell comprising the polymer electrolyte membrane according to claim 13.   An electrochemical hydrogen pump configured using the polymer electrolyte membrane according to claim 13. A water electrolysis hydrogen generator configured using the polymer electrolyte membrane according to claim 13.