JP5250935B2 - POLYMER ELECTROLYTE MATERIAL, POLYMER ELECTROLYTE PARTS, MEMBRANE ELECTRODE COMPOSITE AND POLYMER ELECTROLYTE TYPE FUEL CELL USING SAME - Google Patents

Description

  The present invention relates to a polymer electrolyte material excellent in practical use capable of achieving high output, high energy capacity, and long-term durability, and a polymer electrolyte component, a membrane electrode assembly and a polymer electrolyte fuel using the same It relates to batteries.

  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 low standard operating temperature of 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 polymer electrolyte fuel cells, in addition to conventional polymer electrolyte fuel cells that use hydrogen gas as fuel (hereinafter referred to as PEFC), direct methanol fuel cells that supply methanol directly (hereinafter referred to as DMFC) It is also attracting attention. Since DMFC is liquid and does not use a reformer, it has the advantage that the energy density is high and the usage time of the portable device per filling is long.

  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. 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. In particular, in a polymer electrolyte membrane for DMFC that uses an organic solvent such as methanol as fuel, methanol permeation is called methanol crossover (hereinafter sometimes abbreviated as MCO), which means that battery output and energy efficiency are reduced. Cause problems. Other required characteristics include chemical stability to withstand a strong oxidizing atmosphere during fuel cell operation and mechanical strength to withstand repeated thinning and swelling and drying.

  Until now, Nafion (registered trademark) (Nafion (registered trademark): manufactured by DuPont), which is a perfluorosulfonic acid polymer, has been widely used for the polymer electrolyte membrane. Nafion (registered trademark) is very expensive because it is manufactured through multi-step synthesis, and there is a problem that fuel crossover is large to form a cluster structure. In addition, due to the lack of hot water resistance and methanol resistance, there is a problem that the mechanical strength of the film made by swelling and drying is lowered, a problem that the softening point is low and the film cannot be used at a high temperature, and a disposal problem and materials after use. There was also a problem that it was difficult to recycle. Perfluorosulfonic acid-based membranes have characteristics that are generally balanced as polymer electrolyte membranes, but further improvements in properties have been required as the batteries are put into practical use.

  In order to overcome such drawbacks, several efforts have already been made on polymer electrolyte materials based on non-perfluoropolymer hydrocarbon polymers. As the polymer skeleton, aromatic polyether ketone and aromatic polyether sulfone have been particularly actively studied from the viewpoint of heat resistance and chemical stability.

  For example, a sulfonated product (for example, non-soluble aromatic polyetheretherketone (Victrex (registered trademark) PEEK (registered trademark) (manufactured by Victrex), etc.)), which is an aromatic polyetherketone, is used. Patent Document 1), a narrowly defined polysulfone that is an aromatic polyethersulfone (hereinafter sometimes abbreviated as PSF) (UDEL P-1700 (manufactured by Amoco) and the like) and a narrowly defined polyethersulfone. (Hereinafter, it may be abbreviated as PES.) Sulfonated products (for example, Non-Patent Document 2) of SUMIKAEXCEL (registered trademark) PES (manufactured by Sumitomo Chemical Co., Ltd.) have been reported. When the content of ionic groups is increased to increase conductivity, the created membrane swells, and fuel crossover such as methanol is large. There are cormorants problems, also due to the low cohesive force of polymer molecular chains, poor stability of the conformation, there is a problem that insufficient mechanical strength and physical durability of the film produced.

  Moreover, in the sulfonated product (for example, Patent Documents 1 and 2) of an aromatic polyether ketone (hereinafter sometimes abbreviated as PEK) (including Victrex PEEK-HT (manufactured by Victrex)). A polymer having a low sulfonic acid group density composition due to its high crystallinity has the problem that crystals remain insoluble in a solvent due to residual crystals, resulting in poor processability. Conversely, if the sulfonic acid group density is increased to improve processability, Since the polymer was not crystalline, it swelled remarkably in water, resulting in not only a large fuel crossover but also an insufficient strength of the membrane produced.

  As a method for controlling the amount of sulfonic acid groups, in aromatic polyether sulfone systems, there have been reports of sulfonated aromatic polyether sulfones in which the amount of sulfonic acid groups is controlled by polymerization using monomers introduced with sulfonic acid groups. (For example, refer to Patent Document 3). However, here too, the problem of swelling of the film prepared under high temperature and high humidity is not improved, and this tendency is particularly remarkable in a fuel aqueous solution such as methanol or in a composition having a high sulfonic acid group density. In addition, it has been difficult for a polymer electrolyte membrane having poor heat resistance and methanol resistance to sufficiently suppress fuel crossover such as methanol and to provide mechanical strength that can withstand a swelling and drying cycle.

  Non-Patent Document 3 describes an aromatic polyether ketone polymer having a structural unit represented by the following formula (H1) that does not contain an ionic group. However, since it does not contain an ionic group, it has no idea as a polymer electrolyte material.

As described above, the polymer electrolyte material according to the prior art is insufficient as a means for improving economy, workability, proton conductivity, fuel crossover, mechanical strength, and long-term durability, and is an industrially useful fuel cell. It could not be a polymer electrolyte material for use.
"Polymer", 1987, vol. 28, 1009. “Journal of Membrane Science”, 83 (1993) 211-220. “Macromolecules”, 1987, vol. 20, p.1204. JP-A-6-93114 Japanese translation of PCT publication No. 2004-528683 US Patent Application Publication No. 2002/0091225

  In view of the background of such prior art, the present invention is excellent in proton conductivity and excellent in fuel cutoff, mechanical strength, hot water resistance, hot methanol resistance, workability, chemical stability, and polymer electrolyte type Providing polymer electrolyte materials that can achieve high output, high energy density, and long-term durability when used as fuel cells, and polymer electrolyte components, membrane electrode composites, and polymer electrolyte fuel cells comprising the same To do.

  In the prior art, the method of introducing sulfonic acid groups onto the aromatic ring by polymer sulfonation reaction (polymer reaction) has the problem that the amount and position of the sulfonic acid groups introduced into the polymer cannot be precisely controlled. Therefore, mass production of the polymer has been difficult. Therefore, paying attention to the use of protecting groups for the synthesis of polymer electrolyte materials having ionic groups, we tried to mold them with protecting groups and the membranes made in this way for fuel cell applications. Thus, the present invention has been completed by examining the relationship between mechanical property evaluation, chemical structure and hot water resistance, hot methanol resistance, processability, and the like.

The present invention employs the following means in order to solve the above problems. That is, the polymer electrolyte material of the present invention is a polymer electrolyte material that contains at least a protecting group and an ionic group, and the protecting group is introduced into the main chain , and is a structural unit protected by the protecting group. As a polymer electrolyte material comprising at least one selected from general formulas (P1) and (P2) described later . In addition, the polymer electrolyte component, the membrane electrode assembly, and the polymer electrolyte fuel cell of the present invention are characterized by being configured using such a polymer electrolyte material.

  According to the present invention, high output, high energy capacity and long-term durability are achieved with excellent proton conductivity, excellent fuel cutoff, mechanical strength, hot water resistance, heat resistance methanol resistance, processability, and chemical stability. It is possible to provide a polymer electrolyte material excellent in practicality that can be used, and a high-performance polymer electrolyte component, membrane electrode assembly, and polymer electrolyte fuel cell using the same.

  Hereinafter, the present invention will be described in detail.

The present invention has the above-described problems, that is, excellent in proton conductivity, fuel cutoff, mechanical strength, hot water resistance, heat resistant methanol resistance, processability, and chemical stability, and a polymer electrolyte fuel cell. high power, the polymer electrolyte material capable of achieving high energy density and long durability, intensive study, contains at least the protecting group and an ionic group, that the protecting group has not been introduced into the main chain when It has been clarified that such a problem can be solved all at once when a polymer electrolyte material is used.

  When conventional sulfonated aromatic polyether ketone or sulfonated aromatic polyethersulfone is used as a polymer electrolyte material, the membrane swells when the content of ionic groups is increased to increase proton conductivity, There was a problem that the fuel crossover of methanol or the like was large, a polymer molecular chain was low in cohesion, so that the stability of the polymer higher order structure was poor, and the mechanical strength and physical durability of the membrane were insufficient.

Aromatic polyetherketone (PEK) polymers exhibit crystallinity because of their good packing properties and extremely strong intermolecular cohesive strength, and have the property of not dissolving in general solvents at all. In contrast, the polymer electrolyte material of the present invention reduces the crystallinity of a crystalline polymer such as a PEK polymer, which has been difficult to form, by including a protective group in the polymer main chain. By adding the solubility, it is possible to use it for film formation.

  In addition, after being formed into a film or the like, the molecular chain of the polymer is improved and part of the protecting group is deprotected in order to impart intermolecular cohesive force and crystallinity again. A polymer electrolyte material can be obtained with significantly improved solvent resistance such as methanol, mechanical properties such as tensile strength and elongation, tear strength and fatigue resistance, and fuel barrier properties such as methanol and hydrogen. Through this manufacturing process, the polymer electrolyte membrane of the present invention, in particular, has not only high proton conductivity but also film-forming properties (workability), manufacturing costs, hot water resistance, methanol resistance, fuel barrier properties, and mechanical properties. It has the feature that it can.

  In addition, the polymer electrolyte membrane obtained by the present invention has a property that is very difficult to break even in a water-containing state due to its strong intermolecular cohesion, that is, has a high tear strength, and repeats swelling and drying. It has a feature that it can achieve extremely excellent long-term durability even under the operating conditions of a polymer electrolyte fuel cell using hydrogen as a fuel used in an automobile or the like.

  Furthermore, it becomes possible to form a crystalline polymer film having a low sulfonic acid group density that could not be used because of insufficient solubility, and has both proton conductivity and fuel crossover suppression effect, The present inventors have succeeded in obtaining the polymer electrolyte membrane of the present invention having excellent heat resistance methanol resistance, mechanical properties, physical durability and long-term durability.

  Examples of the protective group used in the polymer electrolyte material of the present invention include those commonly used in organic synthesis, and the protective group is temporarily introduced on the assumption that it is removed at a later stage. It is a substituent to be protected, which protects a highly reactive functional group and renders it inactive to the subsequent reaction, and can be deprotected and returned to the original functional group after the reaction. 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 protective reactions include, for example, Theodora W. Greene, “Protective Groups in Organic Synthesis”, US, John Wiley & Sons, Inc), 1981, which 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 a ketone moiety with an acetal or ketal moiety, and protecting / deprotecting a 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”. Further, a method for de-t- butylated with protection / deprotection as soluble group t- butyl group introduced, and acid and the like in Fang incense ring. However, it is not limited to these and can be preferably used. In terms of improving solubility in a general solvent 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.

As the position of the functional group for introducing the protecting group, it is important to be the main chain of the polymer. Since the polymer electrolyte material of the present invention introduces a protecting group into a polymer having good packing for the purpose of improving processability, the effect of the present invention can be sufficiently obtained even if a protecting group is introduced into the side chain portion of the polymer. It has such. Here, the functional group present in the main chain of the polymer is defined as a functional group that breaks the polymer chain when the functional group is deleted. For example, this means that if the ketone group of the aromatic polyether ketone is deleted, the benzene ring and the benzene ring are broken.

  In the present invention, the polymer being crystalline means that the polymer has a crystallizable property that can be crystallized under some conditions. The term “amorphous polymer” means that the polymer is amorphous when used, regardless of whether the polymer is crystalline or not. The presence or absence of crystallinity of these polymers and the crystalline and amorphous states can be evaluated by sharp peaks derived from crystals in wide-angle X-ray diffraction (XRD), crystallization peaks in differential scanning calorimetry (DSC), and the like. .

  Moreover, in this invention, being excellent in hot water resistance and heat-resistant methanol property means that the dimensional change (swelling) in high-temperature water and high-temperature methanol is respectively small. If this dimensional change is large, the membrane may be broken during use as a polymer electrolyte membrane, or it may swell and peel from the electrode catalyst layer, resulting in an increase in resistance. These hot water resistance and hot methanol properties are both important characteristics required for the electrolyte polymer used in the polymer electrolyte fuel cell.

  The protective reaction used in the polymer electrolyte material of the present invention is more preferably a method of protecting / deprotecting a ketone moiety with an acetal or ketal moiety, and a ketone moiety with an acetal or ketal moiety in terms of reactivity and stability. This is a method of protecting / deprotecting with a heteroatom analog of thioacetal or thioketal. In the polymer electrolyte material of the present invention, the constituent unit containing a protecting group preferably contains at least one selected from the following general formulas (P1) and (P2).

(In the general formulas (P1) and (P2), Ar _{1 to} Ar ₄ are any divalent arylene group, R ₁ and R ₂ are at least one group selected from H and an alkyl group, and R ₃ is any And E represents O or S, and each may represent two or more groups, and the groups represented by the general formulas (P1) and (P2) may be optionally substituted.)
Among them, in the general formulas (P1) and (P2), E is O in terms of the odor, reactivity, stability, etc. of the compound, that is, the ketone moiety is protected / deprotected with an acetal or ketal moiety. The method is most preferred.

The polymer electrolyte material of the present invention is more preferably a polymer having an aromatic ring in the main chain among hydrocarbon polymers from the viewpoints of mechanical strength and chemical stability. That is, it is a polymer having an aromatic ring in the main chain and having an ionic group. The main chain structure is not particularly limited as long as it has an aromatic ring, but preferably has a sufficient mechanical strength to be used, for example, as an engineering plastic. Specific examples of the polymer having an aromatic ring in the main chain used in the polymer electrolyte material of the present invention include polysulfone, polyethersulfone, polyphenylene oxide, polyarylene ether-based polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, Composition of polyarylene polymer, polyarylene ketone, polyether ketone, polyarylene phosphine oxide, polyether phosphine oxoxide, polybenzoxazole, polybenzthiazole, polybenzimidazole, polyamide, polyimide, polyetherimide, polyimidesulfone, etc. Examples include polymers containing at least one of the components. Polysulfone, polyethersulfone, polyetherketone, and the like referred to here are generic names for polymers having a sulfone bond, an ether bond, and a ketone bond in the molecular chain thereof. Polyetherketoneketone, polyetheretherketone, It includes polyether ether ketone ketone, polyether ketone ether ketone ketone, polyether ketone sulfone and the like, and does not limit the specific polymer structure.

Among the polymers having an aromatic ring in the main chain, polysulfone, polyethersulfone, polyphenylene oxide, polyarylene ether polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, polyarylene ketone, polyether ketone, polyarylene phosphine hydroxide, poly A polymer such as ether phosphine oxide is more preferable from the viewpoint of mechanical strength, processability and hydrolysis resistance. Specifically, a polymer containing an aromatic group in the main chain having a repeating unit represented by the following general formula (T1) can be given.

(Here, Z1 and Z2 each represents an organic group containing an aromatic ring, and each may represent two or more groups. At least one of Z1 and Z2 contains an ionic group.) Y1 represents an electron-withdrawing group, Y2 represents O or S. a and b each independently represent 0 or a positive integer, provided that a and b are not 0 at the same time.
Among the polymers containing aromatic groups in the main chain having the repeating unit represented by the general formula (T1), the polymers having the repeating units represented by the general formula (T1-1) to the general formula (T1-6) are resistant to It is more preferable in terms of hydrolyzability, mechanical strength and production cost. Among them, from the viewpoint of mechanical strength and production cost, an aromatic polyether polymer in which Y2 is O is more preferable, and most preferable is a polymer having a repeating unit represented by the general formula (T1-3), that is, aromatic An aromatic polyether ketone polymer is most preferred.

(Here, Z ¹ and Z ² each represent an organic group containing an aromatic ring, and each may represent two or more groups. At least one of Z ¹ and Z ² is ionic.) A and b each independently represents 0 or a positive integer, provided that a and b are not 0 at the same time.)
Preferred organic groups as Z ¹ are a phenylene group and a naphthylene group. These may be substituted.

Preferred examples of the organic groups represented by Z ^p in the general formula (T1-4), a methyl group, an ethyl group, a propyl group, an isopropyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, a vinyl group, an allyl group, a benzyl group A phenyl group, a naphthyl group, a phenylphenyl group, and the like. In terms of ease of industrial availability are the most preferred phenyl group as Z ^p.

  In the present invention, the aromatic polyether-based polymer refers to a polymer mainly composed of an aromatic ring and containing an ether bond as a mode in which the aromatic ring units are connected. In addition to the ether bond, there may be a bond mode generally used for forming an aromatic polymer such as a direct bond, ketone, sulfone, sulfide, various alkylenes, imides, amides, esters, and urethanes. The ether bond is preferably at least one per repeating unit of the main constituent component. 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. Aromatic units include hydrocarbon groups such as alkyl groups, alkoxy groups, aromatic groups, allyloxy groups, halogen groups, nitro groups, cyano groups, amino groups, halogenated alkyl groups, carboxyl groups, phosphonic acid groups, hydroxyl groups, etc. And may have an arbitrary substituent.

  Even when the aromatic polyether polymer contains a bonding mode other than an ether bond such as a direct bond, the position of the protective group to be introduced is the aromatic ether polymer part from the viewpoint of improving processability. Is more preferable.

In the polymer electrolyte material of the present invention, R ₁ and R ₂ in the general formula (P1) are more preferably an alkyl group in terms of stability, and more preferably an alkyl group having 1 to 6 carbon atoms, Most preferred is an alkyl group having 1 to 3 carbon atoms. Moreover, as R < ₃ > in general formula (P2), it is more preferable that it is a C1-C7 alkylene group from a stability point, Most preferably, it is a C1-C4 alkylene group. Specific examples of R3 include —CH ₂ CH ₂ —, —CH (CH ₃ ) CH ₂ —, —CH (CH ₃ ) CH (CH ₃ ) —, —C (CH ₃ ) ₂ CH ₂ —, —C ( CH ₃ ) ₂ CH (CH ₃ ) —, —C (CH ₃ ) ₂ O (CH ₃ ) ₂ —, —CH ₂ CH ₂ CH ₂ —, —CH ₂ C (CH ₃ ) ₂ CH ₂ — and the like. However, it is not limited to these.

As the polymer electrolyte material of the present invention, among the structural units of the general formula (P1) or (P2), those having at least the formula (P2) from the viewpoint of stability such as hydrolysis resistance are more preferably used. It is done. Furthermore, R _{3 in the} general formula (P2) is preferably an alkylene group having 1 to 7 carbon atoms, that is, a group represented by C _n1 H _2n1 (n1 is an integer of 1 to 7). From the viewpoint of ease of synthesis, at least one selected from —CH ₂ CH ₂ —, —CH (CH ₃ ) CH ₂ —, and —CH ₂ CH ₂ CH ₂ — is most preferable.

A preferable organic group as Ar _{1 to} Ar ₄ in the general formulas (P1) and (P2) is a phenylene group, a naphthylene group, or a biphenylene group. These may be optionally substituted. As the aromatic polyether polymer of the present invention, Ar ₃ and Ar ₄ in the general formula (P2) are both a phenylene group from the viewpoint of solubility and availability of raw materials, that is, the following general formula (P3) It is more preferable that Ar ₃ and Ar ₄ are both p-phenylene groups.

(In General Formula (P3), n1 is an integer of 1 to 7. The structural unit represented by General Formula (P3) may be optionally substituted.)
The method for synthesizing the aromatic polyether polymer of the present invention is not particularly limited as long as it is a method capable of substantially increasing the molecular weight. For example, an aromatic active dihalide compound and a dihydric phenol are used. It can be synthesized using an aromatic nucleophilic substitution reaction of a compound or an aromatic nucleophilic substitution reaction of a halogenated aromatic phenol compound.

  Specifically, for example, aromatic polyether polymers containing the structural units represented by the general formulas (P1) and (P2) are represented by the following general formulas (P1-1) and ( It is possible to synthesize by an aromatic nucleophilic substitution reaction with an aromatic active dihalide compound using the compound represented by P2-1). The structural units represented by the general formulas (P1) and (P2) may be derived from either the divalent phenol compound or the aromatic active dihalide compound, but the divalent phenol is considered in consideration of the reactivity of the monomer. More preferably, it is derived from a compound.

(In the general formulas (P1-1) and (P2-1), Ar _{1 to} Ar ₄ are any divalent arylene group, R ₁ and R ₂ are at least one group selected from H and an alkyl group, R ₃ represents an arbitrary alkylene group, and E represents O or S. The compounds represented by the general formula (P1-1) and the general formula (P2-1) may be optionally substituted.
Specific examples of particularly preferred dihydric phenol compounds used in the present invention include compounds represented by the following general formulas (r1) to (r10), and derivatives derived from these dihydric phenol compounds.

  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.

  In the present invention, a method for protecting a ketone moiety with an acetal and / or ketal includes a method in which a precursor compound having a ketone group is reacted with a monofunctional and / or bifunctional alcohol in the presence of an acid catalyst. For example, by reacting the ketone precursor 4,4′-dihydroxybenzophenone in a solvent such as a monofunctional and / or difunctional alcohol, aliphatic or aromatic hydrocarbon in the presence of an acid catalyst such as hydrogen bromide. Can be manufactured. The alcohol is an aliphatic alcohol having 1 to 20 carbon atoms. An improved method for producing acetal and / or ketal monomers for use in the present invention is to react the ketone precursor 4,4'-dihydroxybenzophenone with a bifunctional alcohol in the presence of an alkyl orthoester and a solid catalyst. Become.

  Specific examples of the bifunctional alcohol include ethylene glycol, propylene glycol, 2,3-butanediol, 2-methyl-1,2-propanediol, 2-methyl-2,3-butanediol, and 2,3-dimethyl- Examples include, but are not limited to, 2,3-butanediol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and the like. Of these, ethylene glycol, propylene glycol, 2-methyl-1,2-propanediol are most preferable from the viewpoint of stability.

  Examples of the alkyl orthoester include trimethyl orthoformate, triethyl orthoformate, trimethyl orthoacetate, triethyl orthoacetate, tetramethyl orthosilicate, tetraethyl orthosilicate, and the like. Also, easily hydrolyzed compounds such as 2,2-dimethoxypropane and 2,2-dimethyl-1,3-dioxolane, which form volatile products such as methanol, ethanol, acetone, etc., are orthoesters. It can be used instead.

  The solid catalyst is preferably a finely acidic acidic alumina-silica compound, and most preferably a montmorillonite clay exemplified by montmorillonite called K-10 (for example, a reagent manufactured by Aldrich). Montmorillonite clay is preferred, but other solid acidic catalysts with high surface areas can also function effectively as catalysts. These include acidic alumina, sulfonated polymer resins and the like.

  The reaction is carried out with a ketone precursor, about 1 equivalent or preferably an excess of a bifunctional alcohol, about 1 equivalent or preferably an excess of orthoester and at least 1 g of solid catalyst per equivalent of ketone, preferably 10 mol per equivalent of ketone. It is carried out by mixing the above solid catalysts together. The reaction is performed in the presence of an inert solvent as necessary. A large excess of solid can be used because the catalyst is easily removed by filtration for reuse. The reaction is carried out at a temperature from about 25 ° C. to about the boiling point of the orthoester used, but is preferably carried out at a temperature lower than the boiling point of the orthoester but higher than the boiling point of the orthoester reaction product. For example, when using trimethyl orthoformate (boiling point 102 ° C.) in which the reaction products are methanol (boiling point 65 ° C.) and methyl formate (boiling point 34 ° C.), a reaction temperature of about 65 ° C. to 102 ° C. is preferred. Of course, the reaction temperature can be appropriately adjusted when the reaction is carried out under reduced pressure or elevated pressure.

  The most preferred ketal monomers are 4,4'-dihydroxybenzophenone, excess glycol, excess trialkyl orthoformate and about 0.1 to about 5 g of montmorillonite clay K-10, preferably about 0.5 to about 0.5 g of ketone. It is produced by heating a mixture of 2.5 g of clay to distill off the alcohol obtained from the orthoformate. The ketal-containing monomer 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane can be obtained in excellent yield (60% to almost quantitative) with a reaction time within 48 hours.

  In order to recover the ketal monomer and the unreacted ketone, a standard isolation method can be used if appropriate care is taken not to make the system acidic. Prior to use in the production of the polyketals, recrystallization of the isolated reaction product, or other bulking, does not require purification. For example, the reaction mixture is diluted with ethyl acetate solvent, the solid catalyst is removed by filtration, the solution is extracted with basic water to remove excess alcohol, and water is removed with a conventional desiccant such as anhydrous sodium sulfate. After removing the solvent and volatiles under vacuum and then washing the resulting solid with a solvent such as methylene chloride to remove trace contaminants, it contains mainly ketal monomers but still A reaction product is obtained which may contain unreacted ketone precursors. However, this reaction product can be used in the production of high molecular weight polyketals without further purification. It is also possible to remove the unreacted ketone precursor by recrystallization with a general solvent such as toluene.

  The aromatic active dihalide compound is not particularly limited as long as it can have a high molecular weight by an aromatic nucleophilic substitution reaction with a dihydric phenol compound. More preferable specific examples of the aromatic active dihalide compound include 4,4′-dichlorodiphenyl sulfone, 4,4′-difluorodiphenyl sulfone, 4,4′-dichlorodiphenyl ketone, 4,4′-difluorodiphenyl ketone, 4,4′-dichlorodiphenylphenylphosphine oxide, 4,4′-difluorodiphenylphenylphosphine oxide, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile and the like can be mentioned. Among these, 4,4′-dichlorodiphenyl ketone and 4,4′-difluorodiphenyl ketone are more preferable in terms of imparting crystallinity, mechanical strength, heat-resistant methanol property, and fuel crossover suppressing effect, and 4,4 ′ from the viewpoint of polymerization activity. -Difluorodiphenyl ketone is most preferred. These aromatic active dihalide compounds can be used alone, but a plurality of aromatic active dihalide compounds can also be used in combination.

  As a polymer electrolyte material synthesized using 4,4′-dichlorodiphenyl ketone or 4,4′-difluorodiphenyl ketone as the aromatic active dihalide compound, a constituent represented by the following general formula (P4) is further included. It is included and is preferably used. The aromatic polyether polymer is a structural unit obtained by deprotecting the ketal site in the general formula (P3) and converting it into a ketone group, which becomes a component imparting crystallinity and used as a fuel in methanol water Since it becomes an effective component in forming a material excellent in dimensional stability at high temperature and mechanical strength, it is more preferably used.

(The structural unit represented by the general formula (P4) may be optionally substituted, but does not contain an ionic group.)
The polymer electrolyte material of the present invention includes structural units represented by the following general formula (P5) together with structural units represented by the general formula (P1) and / or (P2) and the general formula (P4). Monomers having an ionic group exemplified by those having them are also preferably used in combination. It is preferable to use a compound in which an ionic acid group is introduced into an aromatic active dihalide compound as a monomer because the amount of the ionic group can be precisely controlled. Examples of monomers having sulfonic acid groups as ionic groups include 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone, 3,3′-disulfonate-4,4′-difluorodiphenylsulfone, 3 3,3′-disulfonate-4,4′-dichlorodiphenyl ketone, 3,3′-disulfonate-4,4′-difluorodiphenyl ketone, 3,3′-disulfonate-4,4′-dichlorodiphenylphenylphosphine And oxide, 3,3′-disulfonate-4,4′-difluorodiphenylphenylphosphine oxide, and the like. In terms of proton conductivity and hydrolysis resistance, a sulfonic acid group is most preferable as an ionic group, but the monomer having an ionic group used in the present invention may have another ionic group. . Among these, 3,3′-disulfonate-4,4′-dichlorodiphenyl ketone and 3,3′-disulfonate-4,4′-difluorodiphenyl ketone are more preferable from the viewpoint of heat resistance methanol resistance and fuel crossover suppression effect. From the viewpoint of polymerization activity, 3,3′-disulfonate-4,4′-difluorodiphenyl ketone is most preferred. Polymer electrolyte material synthesized using 3,3′-disulfonate-4,4′-dichlorodiphenyl ketone, 3,3′-disulfonate-4,4′-difluorodiphenyl ketone as a monomer having an ionic group Is further preferably used because it further contains a structural unit represented by the following general formula (P5). The aromatic polyether polymer has a high crystallinity characteristic of a ketone group, and is a component superior in heat-resistant methanol property to a sulfone group. Since it becomes an effective component for a material having excellent strength, it is more preferably used. These sulfonic acid groups are preferably salted with a monovalent cationic species during polymerization. The monovalent cation species may be sodium, potassium, other metal species, various amines, or the like, but is not limited thereto. These aromatic active dihalide compounds can be used alone, but a plurality of aromatic active dihalide compounds can also be used in combination.

(In General Formula (P5), M ¹ and M ² represent hydrogen, a metal cation, an ammonium cation, and a 1 and a 2 each represent an integer of 1 to 4. The structural unit represented by General Formula (P5) is further optionally substituted. May be.)
When an aromatic polyether polymer is obtained by an aromatic nucleophilic substitution reaction of an aromatic active dihalide compound and a divalent phenol compound, at least the general formula (P1-1) and / or the divalent phenol compound is obtained. Although it is necessary to use what is represented by (P2-1), it is also possible to use other dihydric phenol compounds together. As the dihydric phenol compound to be copolymerized, various dihydric phenol compounds that can be used for the polymerization of an aromatic polyether polymer by an aromatic nucleophilic substitution reaction can be used. Absent. Moreover, what introduce | transduced the sulfonic acid group into these aromatic dihydroxy compounds can also be used as a monomer.

  The halogenated aromatic hydroxy compound is not particularly limited, but 4-hydroxy-4′-chlorobenzophenone, 4-hydroxy-4′-fluorobenzophenone, 4-hydroxy-4′-chlorodiphenyl sulfone, 4-hydroxy-4′-fluorodiphenylsulfone, 4- (4′-hydroxybiphenyl) (4-chlorophenyl) sulfone, 4- (4′-hydroxybiphenyl) (4-fluorophenyl) sulfone, 4- (4′- Examples thereof include hydroxybiphenyl) (4-chlorophenyl) ketone, 4- (4′-hydroxybiphenyl) (4-fluorophenyl) ketone, and the like. These can be used alone or can be used as a mixture of two or more. Further, in the reaction of the activated dihalogenated aromatic compound and the aromatic dihydroxy compound, these halogenated aromatic hydroxy compounds may be reacted together to synthesize an aromatic polyether compound.

  In the polymer electrolyte material of the present invention, it is also preferable to include a protective group for reducing crystallinity in such a halogenated aromatic hydroxy compound. Since the halogen moiety needs to be activated by an electron-withdrawing group, specific examples thereof include the following general formulas (h1) to (h7).

(Where X is F or Cl)
In the polymer electrolyte material of the present invention, the divalent phenol compound used together with the divalent phenol compound represented by the general formula (P1-1) and / or (P2-1) is not particularly limited. In addition, it is possible to select appropriately in consideration of processability, fuel cutoff, mechanical strength, and the like.

  Preferable specific examples of the dihydric phenol residue used in combination include divalent phenol residues represented by the following general formulas (X-1) to (X-28). In the specification of the present invention, the dihydric phenol residue means a structural unit remaining after the corresponding dihydric phenol compound reacts with the aromatic active dihalide.

(N and m are integers of 1 or more, and Rp represents an arbitrary organic group.)

  These may have a substituent and an ionic group. Those having an aromatic ring in the side chain are also preferred specific examples. Moreover, these can also be used together as needed.

  Among these, the dihydric phenol residue represented by the general formulas (X-1) to (X-17) is a dihydric phenol residue that can improve crystallinity depending on the method of use. Due to the improvement in crystallinity, the obtained polymer electrolyte material can be preferably used because it can exhibit performances excellent in mechanical properties, solvent resistance, fuel cutoff properties, long-term durability, and the like. Among these, a dihydric phenol residue represented by the general formulas (X-1) to (X-5), (X-7), (X-14), and (X-17) is most preferable, Preferably, it is a dihydric phenol residue represented by general formulas (X-1) to (X-5).

  Moreover, since the dihydric phenol residue represented by the general formulas (X-18) to (X-28) has an effect of increasing hydrophobicity or rigidity, the fuel permeation suppressing effect is large, and the dimensional stability in the fuel is improved. It can be preferably used because it is effective in improving the properties. Among them, more preferred are those represented by the general formula (X-21) and the general formula (X-22), and particularly preferred is a dihydric phenol residue represented by the general formula (X-21). .

  In the polymer electrolyte material after deprotection obtained by the present invention, the content of the structural unit selected from the general formula (P1) or (P2) is not particularly limited, but mechanical properties, heat-resistant methanol The amount is preferably smaller in view of the property and the fuel crossover suppressing effect, and may be contained in a very small amount. 2 of the general formula (P1) and / or (P2) with respect to the total molar amount of the dihydric phenol residue consisting of the general formula (P1) and / or (P2) and the other dihydric phenol residue. It is preferable that the content of the hydric phenol residue is 50 mol% or less. In particular, the amount is preferably 20 mol% or less, more preferably 5 mol% or less, from the viewpoint of mechanical properties, fuel crossover suppression effect, and dimensional stability.

  When the structural unit represented by the general formula (P1) and / or (P2) is contained in an amount of 50 mol% or more, the breaking strength, elastic modulus, hot water resistance, and fuel crossover suppressing effect may be insufficient. In addition, the acetal group and / or ketal group should be deprotected from the polymer electrolyte membrane having a dihydric phenol residue represented by the general formula (P1) and / or (P2) so that only the ketone group is present. In some cases, the crystallinity becomes too high, which is not preferable. The polyelectrolyte material of the present invention only needs to contain an acetal and / or ketal group even in a very small amount, and only needs to be contained at a level that can be confirmed by these analyses.

  As content of the acetal group and the ketal group contained in the soluble precursor polymer used in the present invention, for example, when the general formulas (P1-1) and (P2-1) are used as a divalent phenol compound, The total molar amount of the general formulas (P1-1) and (P2-1) is preferably 5 mol% or more with respect to the total molar amount of the dihydric phenol compound. If the total molar amount of the said general formula (P1-1) and (P2-1) is less than 5 mol%, solubility may become insufficient and film forming property may become inadequate. The total molar amount of the general formulas (P1-1) and (P2-1) is more preferably 30 mol% or more, and still more preferably 45 mol% or more, from the viewpoint of improving the solubility. Those containing a large amount of the structural unit represented by the general formulas (P1) and / or (P2) are excellent in solubility and workability, and therefore are soluble in producing extremely tough polymer electrolyte membranes. It can be particularly preferably used as a precursor.

  In the polymer electrolyte material of the present invention, the content of the structural unit selected from the general formula (P1) or (P2) is as follows: nuclear magnetic resonance spectrum (NMR), thermogravimetry (TGA), thermal desorption- It can be measured by generated gas analysis by mass spectrometry (TPD-MS), pyrolysis gas chromatograph, pyrolysis GC-MS, infrared absorption spectrum (IR) and the like.

  When the amount of the protective group contained in the polymer electrolyte material of the present invention is large, since it has solvent solubility, nuclear magnetic resonance spectrum (NMR) is suitable for quantification of the protective group. However, if the amount of protecting group is very small and insoluble in the solvent, it may be difficult to accurately quantify by NMR. In such a case, the generated gas analysis by temperature-programmed thermal desorption-mass spectrometry (TPD-MS), pyrolysis gas chromatograph, or pyrolysis GC-MS is a suitable quantitative method.

For example, when the polymer electrolyte material of the present invention contains the general formula (P2) as a structural unit and R3 is —CH ₂ CH ₂ —, temperature-programmed thermal desorption-mass spectrometry (TPD-MS) ) To detect at least C ₂ H ₄ O gas and / or C ₄ H ₈ O ₂ gas.

In the amount of gas generated in the polymer electrolyte material, the sum of the amount of gas generated by C ₂ H ₄ O and the amount of gas generated by C ₄ H ₈ O ₂ is 0.01 wt% or more based on the dry weight of the polymer electrolyte material, 20 More preferably, it is less than or equal to weight percent. The solvent-soluble polymer electrolyte material precursor is more preferably 1% by weight or more and 20% by weight or less from the viewpoint of solvent solubility. On the other hand, when the polymer electrolyte material requires solvent resistance and mechanical properties, it is more preferably 0.01% by weight or more and 1% by weight or less, more preferably 0.01% by weight or more, It is 0.3% by weight or less, most preferably 0.01% by weight or more and 0.1% by weight or less. The content determination of the ketal group by the TPD-MS method of such a polymer electrolyte material is performed by the method of the example.

In the polymerization of the aromatic polyether polymer by the aromatic nucleophilic substitution reaction to obtain the polymer electrolyte material of the present invention, the polymer is obtained by reacting the monomer mixture in the presence of a basic compound. be able to. The polymerization can be carried out in the temperature range of 0 to 350 ° C., but is preferably 50 to 250 ° C. When the temperature is lower than 0 ° C., the reaction does not proceed sufficiently, and when the temperature is higher than 350 ° C., the polymer tends to be decomposed. The reaction can be carried out in the absence of a solvent, but is preferably carried out in a solvent. Solvents that can be used include N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphontriamide and the like. However, it is not limited to these, and any solvent that can be used as a stable solvent in the aromatic nucleophilic substitution reaction may be used. These organic solvents may be used alone or as a mixture of two or more.

  Examples of the basic compound include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, and the like, and those that can convert an aromatic diol into an active phenoxide structure may be used. It can use without being limited to.

  In the aromatic nucleophilic substitution reaction, water may be generated as a by-product. In this case, regardless of the polymerization solvent, water can be removed from the system as an azeotrope by coexisting toluene or the like in the reaction system. As a method for removing water out of the system, a water-absorbing agent such as molecular sieve can also be used. Azeotropic agents used to remove reaction water or water introduced during the reaction generally do not substantially interfere with polymerization, co-distill with water and boil between about 25 ° C and about 250 ° C. Any inert compound. Common azeotropic agents include benzene, toluene, xylene, chlorobenzene, methylene chloride, dichlorobenzene, trichlorobenzene and the like. Of course, it is beneficial to select an azeotropic agent whose boiling point is lower than that of the dipolar solvent used. An azeotropic agent is commonly used, but it is not always necessary when high reaction temperatures are used, such as temperatures above 200 ° C., especially when the inert gas is continuously sparged into the reaction mixture. In general, it is desirable to carry out the reaction in an inert atmosphere and in the absence of oxygen.

  When the aromatic nucleophilic substitution reaction is carried out in a solvent, it is preferable to charge the monomer so that the resulting polymer concentration is 5 to 50% by weight. When the amount is less than 5% by weight, the degree of polymerization tends to be difficult to increase. On the other hand, when the amount is more than 50% by weight, the viscosity of the reaction system becomes too high, and the post-treatment of the reaction product tends to be difficult.

  After completion of the polymerization reaction, the solvent is removed from the reaction solution by evaporation, and the residue is washed as necessary to obtain the desired polymer. In addition, by adding the reaction solution to a solvent having low polymer solubility and high by-product inorganic salt solubility, the inorganic salt is removed, the polymer is precipitated as a solid, and the polymer is obtained by filtering the precipitate. You can also. The recovered polymer is optionally washed with water, alcohol or other solvent and dried. Once the desired molecular weight is obtained, halide or phenoxide end groups can optionally be reacted by introducing a phenoxide or halide end-capping agent that forms a stable end group.

  In the present invention, from the viewpoint of processability, it is necessary to introduce the protective group without deprotecting it until the film-forming stage. Therefore, polymerization and purification are performed in consideration of the conditions under which the protective group can exist stably. There is a need. For example, when acetal and / or ketal is used as a protecting group, the deprotection reaction proceeds under acidic conditions, so the system must be kept neutral or alkaline.

  In the present invention, the method for deprotecting at least a part of the ketone moiety protected with acetal and / or ketal 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 hydrochloric 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, if it is a film with a thickness of 50 μm, it can be easily deprotected by immersing it 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.

  The molecular weight of the polymer used as the polymer electrolyte material of the present invention thus obtained is 10000 to 5 million, preferably 10,000 to 500,000 in terms of polystyrene-converted weight average molecular weight. If it is less than 10,000, the mechanical strength may be insufficient, such as cracking in the molded film. On the other hand, if it exceeds 5 million, there may be problems such as insufficient solubility, high solution viscosity, and poor processability.

The chemical structure of the polymer electrolyte material of the present invention has an S = O absorption of 1,030 to 1,045 cm @ -1, 1,160 to 1,190 cm @ -1, 1,130 to 1, It can be confirmed by C—O—C absorption at 250 cm −1, C═O absorption at 1,640 to 1,660 cm −1, etc., and these composition ratios can be known by neutralization titration of sulfonic acid groups and elemental analysis. Can do. Moreover, the structure can be confirmed from the peak of an aromatic proton of 6.8 to 8.0 ppm, for example, by nuclear magnetic resonance spectrum ( ¹ H-NMR). In addition, the position and arrangement of sulfonic acid groups can be confirmed by solution 13C-NMR and solid 13C-NMR.

  The sulfonic acid group in the polymer used as the polymer electrolyte material of the present invention may be introduced by block copolymerization or random copolymerization. It can be appropriately selected depending on the chemical structure of the polymer used and the high crystallinity. Random copolymerization is more preferable when fuel barrier properties and low water content are required, and block copolymerization is more preferably used when proton conductivity and high water content are required.

  The ionic group used in the present invention is not particularly limited as long as it is a negatively charged atomic group, but is preferably one having 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, R represents an arbitrary atomic 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 them, Na and K that are inexpensive and can easily be proton-substituted without being adversely affected by solubility are more preferably used as the polymer electrolyte material.

  Two or more kinds of these ionic groups can be contained in the polymer electrolyte material, and may be preferable by combining them. The combination is appropriately determined depending on the structure of the polymer. Among them, it is more preferable to have at least a sulfonic acid group, a sulfonimide group, and 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 hydrolysis resistance.

  The amount of sulfonic acid group in the polymer electrolyte material can be expressed as a value of sulfonic acid group density (mmol / g). The sulfonic acid group density of the polymer electrolyte material in the present invention is preferably from 0.1 to 5.0 mmol / g, more preferably from 0.5 to 5.0 in terms of proton conductivity, fuel barrier properties and mechanical strength. 3.0 mmol / g, and most preferably 0.8 to 2.5 mmol / g in terms of fuel crossover. When the sulfonic acid group density is lower than 0.1 mmol / g, sufficient proton generation characteristics may not be obtained due to low proton conductivity. When the sulfonic acid group density is higher than 5.0 mmol / g, it may be used as an electrolyte membrane for a fuel cell. In addition, sufficient water resistance and mechanical strength when containing water may not be obtained.

  Here, the sulfonic acid group density is the number of moles of sulfonic acid groups introduced per gram of the dried polymer electrolyte material, and the larger the value, the greater the amount of sulfonic acid groups. The sulfonic acid group density can be determined by elemental analysis or neutralization titration. Among these, it is preferable to calculate from the S / C ratio using an elemental analysis method for ease of measurement. However, when a sulfur source other than a sulfonic acid group is included, the ion exchange capacity is obtained by a neutralization titration method. You can also. The polyelectrolyte material of the present invention includes an embodiment in which the polymer electrolyte material has a complex composed of a polymer having an ionic group and other components, as will be described later. In this case, the sulfonic acid group density is based on the total amount of the complex Suppose that

The procedure for neutralization titration is as follows. The measurement shall be performed three times or more and the average shall be taken.
(1) The sample is pulverized by a mill, and in order to make the particle diameter uniform, the sample is passed through a 50-mesh mesh sieve and the sample passed through the sieve is used as the measurement sample.
(2) Weigh the sample tube (with lid) with a precision balance.
(3) About 0.1 g of the sample of (1) is put into a sample tube and vacuum dried at 40 ° C. for 16 hours.
(4) Weigh the sample tube with the sample and determine the dry weight of the sample.
(5) Dissolve sodium chloride in a 30 wt% aqueous methanol solution to prepare a saturated saline solution.
(6) Add 25 mL of the saturated salt solution of (5) above to the sample and stir for 24 hours for ion exchange.
(7) Titrate the resulting hydrochloric acid with 0.02 mol / L aqueous sodium hydroxide. Two drops of a commercially available titration phenolphthalein solution (0.1% by volume) as an indicator are added, and the point at which light reddish purple is obtained is the end point.
(8) The sulfonic acid group density is determined by the following formula.

Sulfonic acid group density (mmol / g) =
[Concentration of sodium hydroxide aqueous solution (mmol / ml) × Drip amount (ml)] / Dry weight of sample (g)
The polymer having an ionic group of the present invention contains other components, for example, an inactive polymer or an organic or inorganic compound having no conductivity or ionic conductivity, as long as the object of the present invention is not impaired. It does not matter.

  Examples of a method for introducing an ionic group into these aromatic hydrocarbon polymers include a method of polymerizing using a monomer having an ionic group and a method of introducing an ionic group by a polymer reaction.

  As a method of polymerizing using a monomer having an ionic group, a monomer having an ionic group in a repeating unit may be used, and if necessary, an appropriate protecting group may be introduced to perform a deprotecting group after polymerization. . Such a method is described, for example, in Journal of Membrane Science, 197, 2002, p.231-242.

  The method of introducing an ionic group in a polymer reaction will be described with an example. For example, introduction of a phosphonic acid group into an aromatic polymer is described in Polymer Preprints, 51, 2002, p.750, etc. This is possible by the method described. Introduction of a phosphate group into an aromatic polymer can be achieved by, for example, phosphoric esterification of an aromatic polymer having a hydroxyl group. Introduction of a carboxylic acid group into an aromatic polymer can be performed by oxidizing an aromatic polymer having an alkyl group or a hydroxyalkyl group, for example. Introduction of a sulfate group into an aromatic polymer can be achieved by, for example, sulfate esterification of an aromatic polymer having a hydroxyl group. As a method for sulfonating an aromatic polymer, that is, a method for introducing a sulfonic acid group, for example, a method described in JP-A-2-16126 or JP-A-2-208322 is known. Specifically, for example, an aromatic polymer can be sulfonated by reacting with a sulfonating agent such as chlorosulfonic acid in a solvent such as chloroform, or by reacting in concentrated sulfuric acid or fuming sulfuric acid. . The sulfonating agent is not particularly limited as long as it sulfonates an aromatic polymer, and sulfur trioxide or the like can be used in addition to the above. When the aromatic polymer is sulfonated by this method, the degree of sulfonation can be easily controlled by the amount of the sulfonating agent used, the reaction temperature and the reaction time. Introduction of a sulfonimide group into an aromatic polymer can be achieved, for example, by a method of reacting a sulfonic acid group and a sulfonamide group.

  When the polymer electrolyte material of the present invention is used for a fuel cell, it is usually used in a membrane state and a binder for a catalyst layer.

  The method for converting the polymer electrolyte material of the present invention into a 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 at a stage having a protective group such as acetal and / or ketal, etc. 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 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 after at least a part of the ionic groups is in a metal salt state. If the polymer electrolyte material to be used is polymerized in the form of a metal salt at the time of polymerization, it is preferable to perform film formation and heat treatment as it is. The metal of the metal salt may be any metal that can form a salt with sulfonic acid, 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, and Ba are more preferable, and Li, Na, and K are more preferable. The temperature of this heat treatment is preferably 150 to 550 ° C, more preferably 160 to 400 ° C, and particularly preferably 180 to 350 ° 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, the fuel permeability suppressing effect, elastic modulus, and breaking strength are insufficient. On the other hand, if it is too high, the film material tends to deteriorate. 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 molding by this method, the polymer electrolyte membrane of the present invention can achieve both a good balance between proton conductivity and fuel barrier properties, mechanical properties, long-term durability, and solvent resistance.

  As a specific example of the method for converting the polymer electrolyte material of the present invention into a membrane, a ketone site protected by acetal and / or ketal after producing a membrane composed of the aromatic polyether polymer by the above-mentioned method is used. At least a part is deprotected to form a ketone moiety. This method makes it possible to form a solution of a low sulfonic acid group polymer with poor solubility, achieving both proton conductivity and a fuel crossover suppression effect, excellent solvent resistance, mechanical properties, and dimensional stability. It becomes possible.

  In the present invention, the method for deprotecting a part or all of the ketone moiety protected with acetal and / or ketal to form a ketone moiety is not particularly limited, but includes a method of acid treatment after molding. It is done. Specifically, it is possible to deprotect the molded membrane by immersing it in an aqueous hydrochloric acid or sulfuric acid solution. The acid concentration and aqueous solution temperature take into account the ease of soaking into the molded product. It can be selected appropriately. For example, if the film has a thickness of 50 μm, it 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 8 hours. However, the deprotection conditions are not limited to these, and the deprotection may be performed with an acid gas or an organic acid.

  The polymer electrolyte membrane obtained by the present invention can be further crosslinked in the polymer structure by means such as radiation irradiation, if necessary. By crosslinking such a polymer electrolyte membrane, an effect of further suppressing fuel crossover and swelling with respect to the fuel can be expected, and the mechanical strength may be improved, which may be more preferable. Examples of such radiation irradiation include electron beam irradiation and γ-ray irradiation.

  The film thickness of the polymer electrolyte membrane of the present invention is preferably 1 to 2000 μm. A thickness of more than 1 μm is more preferable for obtaining the strength of a film that can withstand practical use, and a thickness of less than 2000 μm is preferable for reducing the film resistance, that is, improving the power generation performance. A more preferable range of the film thickness is 3 to 500 μm, and a particularly preferable range is 5 to 250 μm. The film thickness can be controlled by the solution concentration or the coating thickness on the substrate.

  In addition, the polyelectrolyte material of the present invention includes additives such as crystallization nucleating agents, plasticizers, stabilizers or mold release agents, antioxidants and the like used in ordinary polymer compounds. It can add within the range which is not warped.

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

The polymer electrolyte membrane of the present invention preferably has a methanol permeation amount per unit area of 40 μmol · min ⁻¹ · cm ⁻² or less with respect to a 30 wt% aqueous methanol solution under the condition of 20 ° C. In the fuel cell using the polymer electrolyte membrane, from the viewpoint of obtaining high output and high energy capacity in a region where the fuel concentration is high, it is desired that the fuel permeation amount is small in order to maintain a high fuel concentration. is there. The amount of methanol permeated is measured after the polymer electrolyte membrane is immersed in pure water at 25 ° C. for 24 hours.

From this viewpoint, 0 μmol · min ⁻¹ · cm ⁻² is most preferable, but from the viewpoint of ensuring proton conductivity, 0.01 μmol · min ⁻¹ · cm ⁻² or more is preferable.

In addition, the polymer electrolyte membrane of the present invention preferably has a proton conductivity per unit area of 1 S · cm ⁻² or more, and more preferably ² S · cm ⁻² or more. Proton conductivity can be measured by the constant potential alternating current impedance method, which is performed as quickly as possible after immersing the polymer electrolyte membrane in pure water at 25 ° C. for 24 hours, taking it out in an atmosphere of 25 ° C. and 50% to 80% relative humidity. it can.

By setting the proton conductivity per unit area to 1 S · cm ⁻² or more, when used as a polymer electrolyte membrane for a fuel cell, sufficient proton conductivity, that is, sufficient battery output can be obtained. Higher proton conductivity is preferable, but a membrane with high proton conductivity is likely to be dissolved or disintegrated by a fuel such as methanol water, and the fuel permeation amount tends to increase, so a practical upper limit is 50 S · cm. ^-2 .

  The polymer electrolyte membrane of the present invention preferably achieves the low methanol permeation amount and the high proton conductivity as described above from the viewpoint of achieving both high output and high energy capacity.

  The polymer electrolyte component of the present invention means a component containing the polymer electrolyte material of the present invention. In the present invention, specific shapes of parts include plates (including films and films), plates, fibers, hollow fibers, particles, lumps, micropores, coatings, and foams. It can take various forms depending on usage, such as body. The polymer can be applied to a wide range of applications because it can improve the design freedom of the polymer and various properties such as mechanical properties and solvent resistance. When the polymer electrolyte material of the present invention is used for a fuel cell, it is particularly suitable for a membrane state and a catalyst layer binder.

  The polymer electrolyte material of the present invention can be applied to various uses. For example, it can be applied to medical applications such as extracorporeal circulation columns and artificial skin, applications for filtration, ion exchange resin applications, various structural materials, and electrochemical applications. It is also suitable as an artificial muscle. 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. Further, among fuel cells, it is suitable for a polymer electrolyte fuel cell, and there are those using hydrogen as a fuel and those using an organic compound such as methanol as a fuel. It is particularly preferably used for a direct fuel cell using at least one selected from a mixture of water and water as fuel. As the organic compound having 1 to 6 carbon atoms, alcohols having 1 to 3 carbon atoms such as methanol, ethanol and isopropyl alcohol, and dimethyl ether are preferable, and methanol is most preferably used.

  The membrane electrode composite of the present invention means a membrane electrode composite containing the polymer electrolyte material of the present invention in a polymer electrolyte membrane or a catalyst layer. Furthermore, the membrane electrode composite is a component in which a polymer electrolyte membrane and an electrode are combined.

  There is no particular limitation on the method of joining the polymer electrolyte membrane and the electrode when using such a polymer electrolyte membrane as a fuel cell, and a known method (for example, a chemical plating method described in Electrochemistry, 1985, 53, p.269. , Applied Electrochemical Society (J. Electrochem. Soc.), Electrochemical Science and Technology, 1988, 135, 9, p.2209. Is possible.

  In the case of integration by heating press, the temperature and pressure may be appropriately selected depending on the thickness of the polymer 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 polymer electrolyte membrane is in a dry state or in a state where water is absorbed. Specific press methods include roll presses that specify pressure and clearance, and flat plate presses that specify pressure. From the viewpoint of industrial productivity and suppression of thermal decomposition of polymer electrolyte materials having ionic groups. It is preferable to perform in the range of 0 ° C to 250 ° C. The pressurization is preferably as weak as possible from the viewpoint of polymer 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 polymer electrolyte membrane are bonded without carrying out the composite by the hot press process. It is one of the preferred options from the viewpoint of preventing short-circuiting of the anode and cathode electrodes to form a stacked fuel cell. In the case of this method, when power generation is repeated as a fuel cell, the deterioration of the polymer electrolyte membrane presumed to be caused by a short-circuited portion tends to be suppressed, and the durability as a fuel cell is improved. Also, when heat-pressing above the softening temperature or glass transition temperature of the polymer electrolyte material, if the decomposition temperature of the ionic group is close, it is difficult to adopt a temperature above the softening temperature or glass transition temperature of the polymer electrolyte material. Thus, decomposition can be suppressed by using this ionic group as a metal salt, and hot pressing can be performed at a temperature higher than the softening temperature or glass transition temperature of the polymer electrolyte material. For example, when the ionic group of the polymer electrolyte material such as the binder in the electrode or the polymer electrolyte membrane is a sulfonic acid group, the sulfonic acid Na is used, and proton bonding is performed with hydrochloric acid, sulfuric acid, etc. after joining by heating press. Manufacturing membrane electrode composites.

  It is also a preferable method that an interfacial resistance reducing layer is interposed between the electrode and the polymer electrolyte membrane when the electrode and the polymer electrolyte membrane are combined. These contact areas can be substantially increased by filling at least a part of the fine gap between the electrode and the polymer electrolyte membrane with the interface resistance-reducing layer, and in the gap, fuel or air used as a fuel cell, In addition, it is possible to prevent an increase in resistance due to the ingress of generated water or carbon dioxide. In addition, the interfacial resistance reducing composition penetrates into the cracks generated in the catalyst layer of the electrode, and the inner wall surface of the crack of the catalyst layer that could not be used for power generation can be used effectively. The contact area can be increased. As a result, the resistance of the membrane electrode assembly decreases, the power density increases, and a high-performance fuel cell can be obtained. Furthermore, it is also possible to cover the protrusions of the electrode base material and catalyst layer, etc., which can reduce the micro short-circuit during the production of the membrane electrode composite and the micro short-circuit in use as a fuel cell, thereby reducing the performance of the membrane electrode composite. The effect which can be suppressed can also be expected. Furthermore, even when the polymer electrolyte membrane has pinholes, surface defects, etc., it can be protected and repaired by the interface resistance reducing layer, and the performance and durability of the membrane electrode assembly can be stabilized.

  This interface resistance reducing layer is not particularly limited as long as it has ion conductivity such as the polymer electrolyte material of the present invention and has resistance to the fuel to be used, but was obtained in the present invention from the viewpoint of mechanical strength and fuel resistance. It is particularly preferred to include a polymer electrolyte material. For example, when a membrane electrode is combined, a composition containing a polymer electrolyte material containing at least a protecting group and an ionic group, a solvent and a plasticizer according to the present invention is used as a precursor for an interface resistance reducing layer. By removing the solvent and plasticizer by drying, extraction washing and the like after the composite, a high-performance membrane electrode assembly having a reduction in interfacial resistance, mechanical strength, and fuel resistance can be obtained. At this time, the interface resistance reducing layer precursor may be formed on the electrode side or the polymer electrolyte membrane side before the composite step.

  Next, an example of an electrode suitable for the membrane electrode assembly of the present invention will be described. Such an electrode comprises a catalyst layer and an electrode substrate. The catalyst layer here is a layer containing a catalyst for promoting an electrode reaction, an electron conductor, an ion conductor, and the like. As the catalyst contained in the catalyst layer, for example, a noble metal catalyst such as platinum, palladium, ruthenium, rhodium, iridium, gold is preferably used. One of these may be used alone, or two or more of them, such as alloys and mixtures, may be used in combination.

  Moreover, when using an electronic conductor (conductive material) for a catalyst layer, a carbon material and an inorganic conductive material are preferably used from the point of electronic conductivity or chemical stability. Among these, amorphous and crystalline carbon materials are mentioned. For example, carbon black such as channel black, thermal black, furnace black, and acetylene black is preferably used because of its electron conductivity and specific surface area. As furnace black, Vulcan XC-72R (registered trademark), Vulcan P (registered trademark), Black Pearls 880 (registered trademark), Black Pearls 1100 (registered trademark), Black Pearls 1300 (registered trademark), Black Pearls manufactured by Cabot Corporation 2000 (Registered Trademark), Legal 400 (Registered Trademark), Ketjen Black International Ketjen Black EC (Registered Trademark), EC600JD, Mitsubishi Chemical Corporation # 3150, # 3250, and the like. Examples include Denka Black (registered trademark) manufactured by Chemical Industries. In addition to carbon black, artificial graphite or carbon obtained from organic compounds such as natural graphite, pitch, coke, polyacrylonitrile, phenol resin, and furan resin can also be used. As the form of these carbon materials, in addition to irregular particles, fibers, scales, tubes, cones, and megaphones can also be used. Moreover, you may use what post-processed these carbon materials.

  Moreover, when using an electronic conductor, it is preferable from the point of electrode performance that it is disperse | distributing uniformly with a catalyst particle. For this reason, it is preferable that the catalyst particles and the electron conductor are well dispersed in advance as a coating liquid. Furthermore, it is also a preferred embodiment to use catalyst-supporting carbon or the like in which the catalyst and the electron conductor are integrated as the catalyst layer. By using this catalyst-supporting carbon, the utilization efficiency of the catalyst is improved, which can contribute to the improvement of battery performance and cost reduction. Here, even when catalyst-supported carbon is used for the catalyst layer, a conductive agent can be added to further increase the electron conductivity. As such a conductive agent, the above-described carbon black is preferably used.

  As the substance having ion conductivity (ion conductor) used in the catalyst layer, various organic and inorganic materials are generally known. However, when used in a fuel cell, sulfone which improves ion conductivity. A polymer having an ionic group such as an acid group, a carboxylic acid group, or a phosphoric acid group (ion conductive polymer) is preferably used. Among them, from the viewpoint of the stability of the ionic group, a polymer having ion conductivity composed of a fluoroalkyl ether side chain and a fluoroalkyl main chain, or the polymer electrolyte material of the present invention and a known hydrocarbon-based polymer. A molecular electrolyte material is preferably used. As the perfluoro-based ion conductive polymer, for example, Nafion (registered trademark) manufactured by DuPont, Aciplex (registered trademark) manufactured by Asahi Kasei Corporation, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., and the like are preferably used. These ion conductive polymers are provided in the catalyst layer in a solution or dispersion state. At this time, the solvent for dissolving or dispersing the polymer is not particularly limited, but a polar solvent is preferable from the viewpoint of the solubility of the ion conductive polymer. Among them, the polymer electrolyte material obtained in the present invention can be most suitably used as a substance (ion conductor) having ion conductivity in the catalyst layer. In particular, in the case of a fuel cell using methanol aqueous solution or methanol as fuel, the polymer electrolyte material obtained by the present invention is effective in durability from the viewpoint of methanol resistance. The polymer electrolyte material of the present invention is processed at the stage of a soluble polymer electrolyte material for molding, and after being made into a MEA, it is deprotected and imparts solvent resistance, thereby achieving both workability and solvent resistance. Preferred binders can be made.

  Since the catalyst and the electronic conductors are usually powders, the ionic conductor usually plays a role of solidifying them. It is preferable from the viewpoint of electrode performance that the ionic conductor is added in advance to a coating liquid containing catalyst particles and an electronic conductor as main constituents when the catalyst layer is prepared, and is applied in a uniformly dispersed state. is there. The amount of the ionic conductor contained in the catalyst layer should be appropriately determined according to the required electrode characteristics and the conductivity of the ionic conductor used, and is not particularly limited, but the weight ratio The range of 1 to 80% is preferable, and the range of 5 to 50% is more preferable. When the ion conductor is too small, the ion conductivity is low, and when it is too much, the gas permeability may be hindered.

  Such a catalyst layer may contain various substances in addition to the catalyst, the electron conductor, and the ionic conductor. In particular, in order to improve the binding property of the substance contained in the catalyst layer, a polymer other than the above-described ion conductive polymer may be included. Examples of such a polymer include fluorine atoms such as polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polyhexafluoropropylene (FEP), polytetrafluoroethylene, and polyperfluoroalkyl vinyl ether (PFA). These copolymers, copolymers of monomer units constituting these polymers and other monomers such as ethylene and styrene, or blend polymers can be used. The content of these polymers in the catalyst layer is preferably in the range of 5 to 40% by weight. When there is too much polymer content, there exists a tendency for an electronic and ionic resistance to increase and for electrode performance to fall.

  In addition, when the fuel is a liquid or gas, the catalyst layer preferably has a structure in which the liquid or gas easily permeates, and preferably has a structure that promotes the discharge of by-products due to the electrode reaction.

  Moreover, as an electrode base material, an electrical resistance is low and what can collect or supply electric power can be used. Further, when the catalyst layer is used also as a current collector, it is not necessary to use an electrode substrate. Examples of the constituent material of the electrode base material include carbonaceous and conductive inorganic substances. For example, a fired body from polyacrylonitrile, a fired body from pitch, a carbon material such as graphite and expanded graphite, stainless steel, molybdenum And titanium. These forms are not particularly limited, and are used, for example, in the form of fibers or particles. From the viewpoint of fuel permeability, fibrous conductive materials (conductive fibers) such as carbon fibers are preferable. As an electrode base material using conductive fibers, either a woven fabric or a non-woven fabric structure can be used. For example, carbon paper TGP series, SO series manufactured by Toray Industries, Inc., carbon cloth manufactured by E-TEK, etc. are used. Examples of the woven fabric include plain weave, oblique weaving, satin weaving, crest weaving, binding weaving, and the like. Moreover, as a nonwoven fabric, it does not specifically limit, such as a paper making method, a needle punch method, a spun bond method, a water jet punch method, and a melt blow method. It may also be a knitted fabric. In these fabrics, especially when carbon fibers are used, a plain fabric using flame-resistant spun yarn is carbonized or graphitized woven fabric, and the flame-resistant yarn is carbonized after being processed into a nonwoven fabric by the needle punch method or water jet punch method. Alternatively, a graphitized nonwoven fabric, a flameproof yarn, a carbonized yarn, or a mat nonwoven fabric by a paper making method using a graphitized yarn is preferably used. In particular, it is preferable to use a nonwoven fabric or cloth from the viewpoint of obtaining a thin and strong fabric.

  Examples of the carbon fiber used for the electrode substrate include polyacrylonitrile (PAN) carbon fiber, phenolic carbon fiber, pitch carbon fiber, and rayon carbon fiber.

In addition, the electrode base material has a water repellent treatment for preventing gas diffusion / permeability deterioration due to water retention, a partial water repellent treatment for forming a water discharge path, a hydrophilic treatment, and a resistance reduction. For example, carbon powder can be added. Further, a conductive intermediate layer containing at least an inorganic conductive substance and a hydrophobic polymer can be provided between the electrode substrate and the catalyst layer. In particular, when the electrode base material is a carbon fiber woven fabric or a nonwoven fabric having a large porosity, by providing the conductive intermediate layer, it is possible to suppress performance degradation due to the catalyst layer soaking into the electrode base material.

Among fuel cells, it is suitable for a polymer electrolyte fuel cell, and there are those using hydrogen as a fuel and those using an organic compound such as methanol as a fuel. It is particularly preferably used for a direct fuel cell using at least one selected from a mixture of water as fuel. As the organic compound having 1 to 6 carbon atoms, alcohols having 1 to 3 carbon atoms such as methanol, ethanol and isopropyl alcohol, and dimethyl ether are preferable, and methanol is most preferably used.

  Fuels for fuel cells using the membrane electrode assembly of the present invention include oxygen, hydrogen and methane, ethane, propane, butane, methanol, isopropyl alcohol, acetone, glycerin, ethylene glycol, formic acid, acetic acid, dimethyl ether, hydroquinone, cyclohexane Examples thereof include organic compounds having 1 to 6 carbon atoms and mixtures of these with water, and may be one kind or a mixture of two or more kinds. In particular, a fuel containing hydrogen and an organic compound having 1 to 6 carbon atoms is preferably used from the viewpoint of power generation efficiency and simplification of the entire battery system, and hydrogen and aqueous methanol are particularly preferable in terms of power generation efficiency. In the case of using an aqueous methanol solution, the concentration of methanol is appropriately selected depending on the fuel cell system to be used, but a concentration as high as possible is preferable from the viewpoint of long-time driving. For example, an active fuel cell having a system for sending a medium necessary for power generation, such as a liquid feed pump or a blower fan, to a membrane electrode assembly, or an auxiliary machine such as a cooling fan, a fuel dilution system, or a product recovery system has a methanol concentration of 30. It is preferable to inject ~ 100% or more of fuel with a fuel tank or fuel cassette, dilute it to about 0.5 to 20% and send it to the membrane electrode assembly. A passive fuel cell without auxiliary equipment has a methanol concentration Is preferable in the range of 10 to 100%.

  Furthermore, the application of the polymer electrolyte fuel cell using the polymer electrolyte material of the present invention is not particularly limited, but a power supply source for a moving 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. Further, a chemical structural formula is inserted in this example, and the chemical structural formula is inserted for the purpose of helping the reader to understand. The chemical structure of the polymerization component of the polymer, the exact composition, the arrangement, the sulfonic acid The position, number, molecular weight, and the like of the group are not necessarily expressed accurately, and are not limited thereto.

(1) Density of sulfonic acid group A sample of a membrane serving as a specimen was immersed in pure water at 25 ° C. for 24 hours, vacuum-dried at 40 ° C. for 24 hours, and then measured by elemental analysis. Carbon, hydrogen, and nitrogen were analyzed by a fully automatic elemental analyzer varioEL, sulfur was analyzed by a flask combustion method / barium acetate titration, and fluorine was analyzed by a flask combustion / ion chromatograph method. The sulfonic acid group density per unit gram (mmol / g) was calculated from the composition ratio of the polymer.

(2) Proton conductivity After immersing the membrane sample in a 30% by weight aqueous methanol solution at 25 ° C. for 24 hours, the membrane sample is taken out in an atmosphere at 25 ° C. and a relative humidity of 50-80%, and proton conduction is performed as quickly as possible by the constant potential AC impedance method Degree A was measured.

  Further, the membrane sample was immersed in pure water at 25 ° C. for 24 hours, and then taken out in an atmosphere at 25 ° C. and a relative humidity of 50 to 80%, and the proton conductivity B was measured as quickly as possible by the constant potential AC impedance method.

As a measuring apparatus, a Solartron electrochemical measurement system (Solartron 1287 Electrochemical Interface and Solartron 1255B Frequency Response Analyzer) was used. The sample was sandwiched between two circular electrodes (made of stainless steel) of φ2 mm and φ10 mm with a weight of 1 kg. The effective electrode area is 0.0314 cm ² . A 15% aqueous solution of poly (2-acrylamido-2-methylpropanesulfonic acid) was applied to the interface between the sample and the electrode. At 25 ° C., a constant potential impedance measurement with an AC amplitude of 50 mV was performed to determine proton conductivity in the film thickness direction.

(3) Weight average molecular weight The weight average molecular weight of the polymer was 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 of lithium bromide) at a flow rate of 0.2 mL / min, and the weight average molecular weight was determined in terms of standard polystyrene.

(4) Hot water resistance and hot methanol resistance The hot water resistance and hot methanol resistance of the electrolyte membrane were evaluated by measuring the dimensional change rate in a 30 wt% methanol aqueous solution at 60 ° 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. After immersing the electrolyte membrane in a 30 wt% aqueous methanol solution at 60 ° C. for 12 hours, the length (L2) was measured again with a caliper, and the size change was visually observed.

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

(6) Nuclear magnetic resonance spectrum (NMR)
Under the following measurement conditions, ¹ H-NMR is measured to confirm the structure and to determine the mixing ratio of 4,4′-dihydroxybenzophenone and 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane. It was. The mixing ratio (mol%) is a peak observed at 7.6 ppm (derived from 4,4′-dihydroxybenzophenone) and 7.2 ppm (derived from 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane). Calculated from the integrated value.

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)
Accumulation count: 16 times Further, solid ¹³ C-CP / MAS spectrum was measured under the following measurement conditions, and the presence or absence of a ketal group was confirmed.

Apparatus: CMX-300 Infinity manufactured by Chemagnetics
Measurement temperature: Room temperature Internal reference material: Si rubber (1.56ppm)
Measurement nucleus: 75.188829 MHz
Pulse width: 90 ° pulse, 4.5 μsec
Pulse repetition time: ACQTM = 0.03413sec, PD = 9sec
Spectrum width: 30.003 kHz
Sample rotation: 7 kHz
Contact time: 4msec
(7) Methanol Permeation A film-like sample was immersed in hot water at 25 ° C. for 24 hours and then measured at 20 ° C. using a 1 mol% methanol aqueous solution.

A sample membrane was sandwiched between the H-type cells, and pure water (60 mL) was placed in one cell, and 1 mol% aqueous methanol solution (60 mL) was placed in the other cell. The cell capacity was 80 mL each. Moreover, the opening area between cells was 1.77 cm < ² >. Both cells were stirred at 20 ° C. The amount of methanol eluted in pure water at the time of 1 hour, 2 hours and 3 hours was measured and quantified with a gas chromatography (GC-2010) manufactured by Shimadzu Corporation. The methanol permeation amount per unit time was determined from the slope of the graph.

(10) Analysis of residual amount of ketal group (TPD-MS measurement) The polymer electrolyte material to be a sample is subjected to gas analysis during heating under the following conditions, C ₂ H ₄ O, etc. (m / z = 29) The residual amount (wt%) of the ketal group was determined from the sum of 2-methyl-1,3-dioxolane (m / z = 73).
A. Equipment used
TPD-MS equipment <Main specifications>
Heating unit: TRC heating device (electric heater type heating furnace, quartz glass reaction tube)
MS Department: Shimadzu GC / MS QP5050A
B. Test conditions Heating temperature conditions: Room temperature to 550 ° C (Temperature increase rate 10 ° C / min)
Atmosphere: He flow (50mL / min) (Iwatani Corp., purity 99.995%)
C. Sample Amount of sample used: about 1.5mg
Pretreatment: vacuum drying at 80 ° C. for 180 minutes Standard sodium tungstate dihydrate (H ₂ O standard sample): Sigma Aldrich, special grade 99%
1-butene (organic component standard sample): GL science, 7.92% / N ₂ balance Carbon dioxide: GL science, 99.9%
Sulfur dioxide: Sumitomo Seika, 1.000% / N ₂ balance Phenol: Wako Pure Chemicals, special grade 99.0%
2-methyl-1,3-dioxolane (C ₂ H ₄ O, etc. and 2-methyl-1,3-dioxolane standard sample): Tokyo Chemical Industry, special grade 98%
E. Measurement room temperature (room temperature range)

23 ± 2 ℃
Synthesis example 1
Synthesis of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane represented by the following general formula (G1)

  Montmorillonite clay K10 (150 g) and 99 g of dihydroxybenzophenone were reacted at 110 ° C. while distilling the produced by-products in 242 mL of ethylene glycol / 99 mL of trimethyl orthoformate. After 18 hours, 66 g of trimethyl orthoformate was added and reacted for 48 hours of synthesis. To the reaction solution was added 300 mL of ethyl acetate, and after filtration, extraction was performed 4 times with a 2% aqueous sodium hydrogen carbonate solution. Further, after concentration, the desired 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane was obtained by recrystallization from dichloroethane.

Synthesis example 2
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 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 obtained precipitate was separated by filtration and recrystallized with an aqueous ethanol solution to obtain disodium 3,3′-disulfonate-4,4′-difluorobenzophenone represented by the above 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 a polymer represented by the following general formula (G3)

(In the general formula, * represents that the right end of the upper general formula and the left end of the lower general formula are bonded at that position.)
3.5 g of potassium carbonate, 5.2 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxane obtained in Synthesis Example 1, 1.1 g of 4,4′-difluorobenzophenone, and Synthesis Example 2 Polymerization was performed at 190 ° C. in N-methylpyrrolidone (NMP) using 6.3 g of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in the above. Purification was performed by re-precipitation with a large amount of water to obtain a polymer electrolyte material represented by the above general formula (G3). The weight average molecular weight was 230,000.

  The obtained 25 wt% N-methylpyrrolidone (NMP) solution in which the polymer electrolyte material of the general formula (G3) was dissolved was cast on a glass substrate, dried at 100 ° C. for 4 hours, and then at 200 ° C. under nitrogen. For 10 minutes to obtain a polymer electrolyte membrane. The solubility of the polymer electrolyte material was very good. After immersing in 1N hydrochloric acid at 25 ° C. for 24 hours to carry out proton substitution and deprotection, it was immersed in a large excess amount of pure water for 24 hours and thoroughly washed.

The obtained membrane had a thickness of 41 μm and a proton conductivity A per area of 5.1 S / cm ² . Further, almost no dimensional change was observed in a 60 ° C., 30 wt% methanol aqueous solution, the conductivity was high, and the heat resistant methanol resistance was excellent. Moreover, the presence of a ketal group could be confirmed from IR.

Example 2
Synthesis of a polymer represented by the following general formula (G4)

(In the general formula, * represents that the right end of the upper general formula and the left end of the lower general formula are bonded at that position.)
3.5 g of potassium carbonate, 2.6 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxane obtained in Synthesis Example 1, 3.5 g of 4,4′-dihydroxytetraphenylmethane, 4,4 Using 190 g of '-difluorobenzophenone and 2.5 g of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 2 above, in N-methylpyrrolidone (NMP) at 190 ° C. The polymerization was carried out at Purification was carried out by reprecipitation with a large amount of water to obtain a polymer represented by the above general formula (G4). The weight average molecular weight of the obtained polymer was 240,000.

  A film was prepared by the method described in Example 1 except that the polymer of the general formula (G3) was changed to the polymer of the general formula (G4). The solubility of the polymer was very good.

The obtained membrane had a thickness of 43 μm and a proton conductivity A per area of 5.6 S / cm ² . Further, almost no dimensional change was observed in a 60 ° C., 30 wt% methanol aqueous solution, the conductivity was high, and the heat resistant methanol resistance was excellent. Moreover, the presence of a ketal group could be confirmed from IR.

Synthesis example 3
Synthesis of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane (K-DHBP) represented by the formula (G1) In a 3 L flask equipped with a Teflon (registered trademark) stirring blade and a thermometer 4,4′-dihydroxybenzophenone (495 g, DHBP, Tokyo Kasei Reagent) and montmorillonite clay K10 (750 g, Aldrich Reagent) were added, and after nitrogen substitution, ethylene glycol (1200 mL, Wako Pure Chemical Reagent) / trimethyl orthoformate (500 mL) , Wako Pure Chemical Reagent). While stirring, at a bath temperature of 110 ° C./inner temperature of 74 ° C./steam temperature of 52 ° C., methanol and methyl formate were reacted together with trimethyl orthoformate for 8 hours while gradually distilling. Next, 500 mL of trimethyl orthoformate was added, and the mixture was further reacted for 8 hours.

After dilution with 1 L of ethyl acetate, the clay was removed by filtration, and a washing solution of ethyl acetate 500 mL × 3 was also added. Extraction was performed 4 times with 1 L of 2% NaHCO ₃ aqueous solution and once with 1 L of saturated brine, dehydrated with Na ₂ SO ₄ and concentrated. Dichloromethane (500 mL) was added to the obtained white slurry solution, and filtration and washing with dichloromethane (250 mL × 3) were performed to obtain the target K-DHBP / DHBP mixture as a pale yellow solid (yield: 347 g, K-DHBP / DHBP = 94/6 (mol%)). The structure was confirmed by ¹ H-NMR, and the ratio of K-DHBP / DHBP was calculated. Other impurities were not observed by gas chromatography.

Example 3
Synthesis of a polymer represented by the following general formula (G5)

(In the general formula, * represents that the right end of the upper general formula and the left end of the lower general formula are bonded at that position. The sulfonic acid group is described in the Na type, but the K type is changed during the polymerization. (Includes substituted moieties. All bisphenol residues are listed as K-DHBP residues, but include DHBP residues.)
In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 13.82 g of potassium carbonate (Aldrich reagent, 100 mmol), K-DHBP / DHBP obtained in Synthesis Example 3 above = 94/6 (mol%) ) 20.4 g (80 mmol) of the mixture, 12.2 g of 4,4′-difluorobenzophenone (Aldrich reagent, 56 mmol), and disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 2 10.1 g (24 mmol) was added, and after nitrogen substitution, dehydration was performed at 110 ° C. in 110 mL of N-methylpyrrolidone (NMP) and 55 mL of toluene, and then the temperature was raised to remove toluene, and polymerization was performed at 230 ° C. for 5 hours. Purification was performed by reprecipitation with a large amount of water to obtain a soluble polymer electrolyte material for molding represented by the above general formula (G5). The weight average molecular weight was 210,000.

In the solid ¹³ C-CP / MAS spectrum, peaks derived from ketal groups were observed at chemical shifts of about 65 ppm and about 110 ppm. Furthermore, was subjected to quantitative analysis of the ketal group derived materials by TPD-MS measurement for molding the soluble polymer electrolyte material represented by the general formula (G5), etc. _C 2 _{H 4} O per 250 ° C. is 5.10w %, 2-methyl-1,3-dioxolane was 0.43 wt%, and a total of 5.53 wt% of ketal group-derived substances were detected.

Example 4
A 25 wt% N-methylpyrrolidone (NMP) solution in which the molding soluble polymer electrolyte material of general formula (G5) obtained in Example 3 was dissolved was pressure filtered using a glass fiber filter, and then on a glass substrate. And dried at 100 ° C. for 4 hours, heated to 250 ° C. under nitrogen for 30 minutes, and heat-treated at 250 ° C. for 10 minutes to obtain a film. The solubility of the soluble polymer electrolyte material for molding was very good. After being immersed in 6N hydrochloric acid at 95 ° C. for 24 hours for proton substitution and deprotection, it was immersed in a large excess of pure water for 24 hours and washed sufficiently to obtain a polymer electrolyte membrane.

  The evaluation results are summarized in Table 1. The obtained polymer electrolyte membrane was excellent in fuel barrier properties while maintaining conductivity. Moreover, even if it was immersed in hot water or hot methanol, it was a tough film without dissolving or disintegrating, and it was extremely excellent in hot water resistance and hot methanol resistance.

Moreover, in the solid ¹³ C-CP / MAS spectrum, peaks of chemical shifts of about 65 ppm and about 110 ppm (derived from ketal groups) recognized in the film before deprotection are almost observed in the polymer electrolyte film after deprotection. There wasn't. Therefore, the deprotection reaction proceeded at a high conversion rate.

Example 5
In Example 4, a polymer electrolyte membrane was prepared by the method described in Example 4 except that the conditions for proton substitution and deprotection were changed by immersion in 1N hydrochloric acid at 25 ° C. for 24 hours.

  The evaluation results are summarized in Table 1. It was an extremely tough electrolyte membrane. While maintaining conductivity, it was excellent in fuel cutoff.

In addition, in the solid ¹³ C-CP / MAS spectrum, peaks of chemical shifts of about 65 ppm and about 110 ppm (derived from ketal groups) observed in the membrane before deprotection are also observed in a small amount in the polymer electrolyte membrane after deprotection. It was. Therefore, the deprotection reaction proceeded at a relatively high conversion rate.

Example 6
Charge of 12.2 g of 4,4′-difluorobenzophenone (Aldrich reagent, 56 mmol) and 10.1 g (24 mmol) of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 2 A soluble polymer electrolyte material for molding and a polymer electrolyte membrane were prepared by the method described in Example 4 except that 1 was changed to 10.5 g (48 mmol) and 13.5 g (32 mmol), respectively. The weight-average molecular weight of the molding soluble polymer electrolyte material was 250,000.

  The evaluation results are summarized in Table 1. The obtained polymer electrolyte membrane was a very tough electrolyte membrane. While maintaining conductivity, it was excellent in fuel cutoff.

Moreover, in the solid ¹³ C-CP / MAS spectrum, peaks of chemical shifts of about 65 ppm and about 110 ppm (derived from ketal groups) recognized in the film before deprotection are almost observed in the polymer electrolyte film after deprotection. There wasn't. Therefore, the deprotection reaction proceeded at a high conversion rate.

Example 7
Charge of 12.2 g of 4,4′-difluorobenzophenone (Aldrich reagent, 56 mmol) and 10.1 g (24 mmol) of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 2 A soluble polymer electrolyte material for molding and a polymer electrolyte membrane were prepared by the method described in Example 4 except that γ was changed to 8.7 g (40 mmol) and 13.5 g (40 mmol), respectively. The weight-average molecular weight of the soluble polymer electrolyte material for molding was 190,000.

  The evaluation results are summarized in Table 1. The obtained polymer electrolyte membrane was a very tough electrolyte membrane. The conductivity was high and the fuel cutoff was relatively good.

Moreover, in the solid ¹³ C-CP / MAS spectrum, peaks of chemical shifts of about 65 ppm and about 110 ppm (derived from ketal groups) recognized in the film before deprotection are almost observed in the polymer electrolyte film after deprotection. There wasn't. Therefore, the deprotection reaction proceeded at a high conversion rate.

Comparative Example 1
A commercially available Nafion (registered trademark) 117 membrane (manufactured by DuPont) was used to evaluate ion conductivity, MCO and heat-resistant methanol resistance. The Nafion (registered trademark) 117 membrane was immersed in 5% hydrogen peroxide water at 100 ° C. for 30 minutes, then in 5% dilute sulfuric acid at 100 ° C. for 30 minutes, and then thoroughly washed with deionized water at 100 ° C. .

The film thickness was 209 μm, and the proton conductivity A per area was 5.0 S / cm ² . In addition, a dimensional change (swelling) of about 20% was observed in a 60 wt. C., 30 wt% aqueous methanol solution. The conductivity was high, but the heat-resistant methanol resistance was insufficient.

  The evaluation results are summarized in Table 1. The conductivity was high, but the fuel cutoff was inferior.

Comparative Example 2
Various properties were evaluated using a commercially available Nafion (registered trademark) 111 membrane (manufactured by DuPont). The Nafion (registered trademark) 111 membrane was immersed in 5% hydrogen peroxide water at 100 ° C. for 30 minutes, and subsequently immersed in 5% dilute sulfuric acid at 100 ° C. for 30 minutes, and then thoroughly washed with deionized water at 100 ° C. .

  The evaluation results are summarized in Table 1. The conductivity was high, but the fuel cutoff was inferior.

Comparative Example 3
Sulfonation of PEEK 10 g of polyetheretherketone (Victrex (registered trademark) PEEK (registered trademark) (manufactured by Victrex)) was reacted in 100 mL of concentrated sulfuric acid at 25 ° C. for 20 hours. By gradually throwing it into a large amount of water, a sulfonated product of polyetheretherketone was obtained. The resulting polymer had a sulfonic acid group density of 2.1 mmol / g. Since the polymer is sulfonated while being dissolved, it is difficult to obtain the position and amount of the sulfonic acid group with good reproducibility.

  A 25 wt% N-methylpyrrolidone (NMP) solution in which the resulting sulfonated product was dissolved was subjected to pressure filtration using a glass fiber filter, and then cast on a glass substrate, dried at 100 ° C. for 4 hours, Got. The solubility of the polymer was good. The polymer electrolyte membrane was obtained by immersing in a large excess of pure water for 24 hours and thoroughly washing.

  The evaluation results are summarized in Table 1. The conductivity was relatively high, but the fuel shut-off property was inferior. Moreover, it collapsed in 60 degreeC and 30 wt% methanol aqueous solution, or 95 degreeC hot water.

Comparative Example 4
Sulfonation of PEK 10 g of polyetherketone (manufactured by Victorex) was reacted in 100 mL of fuming sulfuric acid at 100 ° C. for 2 hours. After diluting with concentrated sulfuric acid, it was gradually poured into a large amount of water to obtain a polyether ketone sulfonated product SPEK-2. The sulfonic acid group density of the obtained SPEK-2 was 1.2 mmol / g.

The SPEK-2 polymer could not be dissolved in N-methylpyrrolidone (NMP), and film formation was difficult. The composition was similar to the polymer of Example 1, but poor in solubility. Further, the presence of a ketal group could not be confirmed from IR, solid ¹³ C-CP / MAS spectrum, and TPD-MS.

Comparative Example 5
The method described in Example 3 was used except that the amount of 20.4 g (80 mmol) of the K-DHBP / DHBP = 94/6 (mol%) mixture obtained in Synthesis Example 3 was changed to 17.1 g (80 mmol) of DHBP. Polymerization of polyetherketone polymer was performed. From the initial stage of polymerization, a polymer was precipitated, and the polymerization was difficult. Molecular weight could not be measured due to solvent insolubility. Since the solubility was insufficient, the film could not be formed and various measurements could not be performed.

  The evaluation results of Examples 3 to 7 and Comparative Examples 1 to 3 are shown in Table 1. The soluble polymer electrolyte material for molding of Examples 3 to 7 was excellent in solubility. In addition, the polymer electrolyte membranes of Examples 3 to 7 were excellent in proton conductivity and excellent in fuel cutoff. The electrolyte membrane of the comparative example was inferior in fuel barrier properties.

  The electrolyte membrane 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 a methanol aqueous solution as a fuel.

The use of the polymer electrolyte fuel cell of the present invention is not particularly limited, but mobile 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 (17)

Contains at least protecting group and an ionic group, the protecting group is a high molecular electrolyte material that is introduced into the main chain, as a structural unit protected by the protecting group, the following general formula (P1) and (P2 A polymer electrolyte material comprising at least one selected from

(In the general formulas (P1) and (P2), Ar _{1 to} Ar ₄ are any divalent arylene group, R ₁ and R ₂ are at least one group selected from H and an alkyl group, and R ₃ is any And E represents O or S, each of which may represent two or more groups, and the structural units represented by the formulas (P1) and (P2) may be optionally substituted.) In the general formula (P1) and (P2), a polymer electrolyte material according to claim 1, characterized in that E is O. The polymer electrolyte material according to claim 1 or 2 , wherein the polymer electrolyte material is an aromatic polyether polymer. As the structural unit containing the protecting group, the polymer electrolyte material according to any one of claims 1 to 3, characterized by containing the structural unit represented by at least the following general formula (P3).

(N1 in General Formula (P3) is an integer of 1 to 7. The structural unit represented by General Formula (P3) may be optionally substituted.) Temperature heat desorption - in generating gas analysis by mass spectrometry, at least C _{2 H} 4 _O gas and / or C ₄ polymer electrolyte material according to claim 1 H ₈ O ₂ gas is characterized in that it is detected . The total amount of C ₂ H ₄ O generated gas and C ₄ H ₈ O ₂ generated gas is 0.01 wt% or more and 20 wt% or less with respect to the dry weight of the polymer electrolyte material. The polymer electrolyte material according to claim 5 . The polymer electrolyte material according to any one of claims 1 to 6 , wherein the polymer electrolyte material further contains a structural unit represented by the following general formula (P4).

(The structural unit represented by the general formula (P4) may be optionally substituted, but does not contain an ionic group.) The polymer electrolyte material according to any one of claims 1 to 7 , wherein the polymer electrolyte material further contains a structural unit represented by the following general formula (P5).

(In General Formula (P5), M ¹ and M ² represent hydrogen, a metal cation, an ammonium cation, and a1 and a2 each represent an integer of 1 to 4. The structural unit represented by General Formula (P5) is optionally substituted. May be.) The polymer electrolyte material further contains at least one structural unit selected from the following general formulas (X-1) to (X-5), according to any one of claims 1 to 8 . Polymer electrolyte material.

(The groups represented by the formulas (X-1) to (X-5) may be optionally substituted.) The ionic group is a sulfonic acid group, a sulfonimide group, sulfuric acid group, phosphonic acid group, to any one of claims 1 to 9, characterized in that at least one selected from phosphoric acid group and a carboxylic acid group The polymer electrolyte material described. The polymer electrolyte material according to claim 10 , wherein the ionic group is a sulfonic acid group. The polymer electrolyte material according to claim 11 , wherein the sulfonic acid group density is 0.5 to 3.0 mmol / g. Containing acetal and / or ketal site as building blocks containing the protecting group, according to any one of claims 1 to 12, characterized by providing a portion of it allowed deprotection ketone site of the protecting group Polymer electrolyte material. Polyelectrolyte component, characterized in that it is constructed using the polymer electrolyte material according to any one of claims 1 to 13. A membrane electrode assembly comprising the polymer electrolyte material according to any one of claims 1 to 13 . A polymer electrolyte fuel cell comprising the polymer electrolyte material according to any one of claims 1 to 13 . Polymer electrolyte fuel cell, an organic compound having 1 to 6 carbon atoms, and that in claim 16, wherein at least one selected from a mixture thereof with water is a direct-type fuel cell to the fuel The polymer electrolyte fuel cell as described.