JP4867174B2 - POLYMER ELECTROLYTE MATERIAL, POLYMER ELECTROLYTE MEMBRANE, MEMBRANE ELECTRODE COMPOSITION 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 and high energy capacity, and a polymer electrolyte membrane, a membrane electrode assembly and a polymer electrolyte fuel cell using the same. .

  A fuel cell is a power generation device with low emissions, high energy efficiency, and low environmental burden. For this reason, it is in the spotlight again in recent years to the protection of the global environment. Compared to conventional large-scale power generation facilities, this is a power generation device expected in the future as a relatively small-scale distributed power generation facility, and as a power generation device for mobile objects such as automobiles and ships. 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. Although the DMFC has a lower output than the conventional PEFC, the fuel is liquid and does not use a reformer. Therefore, the energy density is high and the usage time of the portable device per filling is long. is there.

  In a fuel cell, an anode electrode and a cathode electrode in which a reaction responsible for power generation occurs and an electrolyte membrane serving as an ionic conductor between the anode and the cathode are a membrane-electrode complex (hereinafter sometimes abbreviated as MEA). A cell in which this MEA is sandwiched between separators is configured as a unit. Here, the electrode is composed of an electrode substrate (also referred to as a gas diffusion electrode or a current collector) that promotes gas diffusion and collects (supply) electricity, and an electrode catalyst layer that actually becomes an electrochemical reaction field. ing. For example, in an anode electrode of a polymer electrolyte fuel cell, a fuel such as hydrogen gas reacts with a catalyst layer of the anode electrode to generate protons and electrons, and the electrons are conducted to the electrode substrate, and the protons flow to the polymer electrolyte membrane. Conducted with. For this reason, the anode electrode is required to have good gas diffusibility, electron conductivity, and ion conductivity. On the other hand, in the cathode electrode, an oxidizing gas such as oxygen or air is reacted with protons conducted from the polymer electrolyte membrane and electrons conducted from the electrode base material in the catalyst layer of the cathode electrode to produce water. For this reason, in the cathode electrode, it is necessary to efficiently discharge the generated water in addition to gas diffusibility, electron conductivity, and ion conductivity.

  In particular, among polymer electrolyte fuel cells, the polymer electrolyte membrane for DMFC using an organic solvent such as methanol as the fuel has the performance required for the conventional polymer electrolyte membrane for PEFC using hydrogen gas as the fuel. In addition, fuel permeation suppression such as methanol is also required. Methanol permeation of the polymer electrolyte membrane is also referred to as methanol crossover (hereinafter sometimes abbreviated as MCO) or chemical short, and causes a problem that the battery output and energy efficiency are lowered.

  So far, for example, Nafion (registered trademark of Nafion, DuPont), which is a perfluorosulfonic acid polymer, has been used in an electrolyte membrane of a polymer electrolyte fuel cell. However, Nafion is a perfluoro polymer produced through multi-step synthesis, so it is very expensive, and in order to form a cluster structure, fuel such as methanol with high affinity for water is used as the electrolyte. There was a problem that the membrane easily permeates, that is, the fuel crossover is large. In addition, since the hot water resistance and methanol resistance are insufficient, there is a problem that the mechanical strength of the film is reduced due to swelling, and further there are problems of disposal treatment after use and difficulty in recycling materials. Therefore, in order to put these polymer electrolyte fuel cells into practical use, polymer electrolyte materials that are inexpensive and have suppressed fuel crossover have been desired from the market.

  Here, 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 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. Moreover, being excellent in radical resistance means being excellent in Fenton resistance, which is generally a measure of power generation durability. If an electrolyte polymer inferior in radical resistance is used, it is not preferable because the molecular weight of the polymer is reduced during power generation, the membrane is damaged, or the proton conductivity is lowered. These characteristics of hot water resistance, methanol resistance and radical resistance are all important characteristics required for the electrolyte polymer used in the polymer electrolyte fuel cell.

  In order to overcome such drawbacks, some efforts have already been made on polymer electrolyte materials based on non-perfluoro 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 of a poorly soluble aromatic polyetheretherketone (hereinafter sometimes abbreviated as PEEK) (for example, see Non-Patent Document 1), a polysulfone that is an aromatic polyethersulfone (hereinafter referred to as PSF). (It may be abbreviated.) (UDEL P-1700 (made by Amoco) and the like) and polyethersulfone (hereinafter sometimes abbreviated as PES) (Victrex PES 5200P (made by ICI)) and the like. ) Has been reported (for example, Non-Patent Document 2) and the like, but it has a problem that the polymer swells under high temperature and high humidity, particularly in a fuel aqueous solution such as methanol or in a composition in which the sulfonic acid group density is high. The tendency was remarkable. In addition, the method of introducing sulfonic acid groups onto the aromatic ring by sulfonation reaction (polymer reaction) of these polymers has a problem that the amount and position of the sulfonic acid groups introduced into the polymer cannot be precisely controlled. It was. As a method for improving this, a sulfonated aromatic polyether sulfone having a controlled amount of sulfonic acid group obtained by polymerization using a monomer having a sulfonic acid group introduced therein has been reported (for example, see Patent Document 1). . However, the problem that the polymer swells under high temperature and high humidity is not improved here either, especially in a fuel aqueous solution such as methanol or in a composition having a high sulfonic acid group density. It has been difficult to sufficiently suppress fuel crossover of methanol or the like with an electrolyte membrane having inferior methanol properties. Furthermore, these polymers have a problem that they are inferior in Fenton resistance (radical resistance), which is a measure of power generation durability. Non-Patent Document 3 describes an aromatic polyether polymer having a structural unit represented by the following formula (H1) that does not contain an ionic group. However, there is no mention of any attempt to introduce an ionic group or a study with a view to an electrolyte polymer for a fuel cell, as well as the chemical structure of the polymer, hot water resistance, heat resistance methanol resistance, and radical resistance resistance. There was no description of the relationship with sex.

Thus, none of the polymer electrolyte materials known so far satisfy all of the above-described high proton conductivity, fuel crossover suppression effect, hot water resistance, heat resistance methanol resistance, radical resistance, economy, The development of a polymer electrolyte material that satisfies high demands has been awaited.
"Polymer", 1987, vol. 28, 1009. "Journal of Membrane Science", 83 (1993) 211-220. “Macromolecules”, 1999, vol. 32, 4279. US 2002-0091225

  In view of the background of such prior art, the present invention achieves both high proton conductivity and low fuel crossover, is excellent in hot water resistance, heat resistance methanol resistance, and radical resistance, and when used as a polymer electrolyte fuel cell. It is an object of the present invention to provide a polymer electrolyte material capable of achieving a high output and a high energy density, and a polymer electrolyte membrane, a membrane electrode assembly and a polymer electrolyte fuel cell comprising the same.

The present invention employs the following means in order to solve the above problems. That is, the polymer electrolyte material of the present invention includes at least an aromatic polyether polymer having structural units represented by the following general formula (P1) and the following general formula (A1), and the aromatic polyether polymer. There possess an ionic group, a _{Q 1} and _{Q 2} is a perfluoroalkyl group, in which Ar ₁ is wherein Rukoto selected from the following general formula (P6) ~ (P8). In addition, the polymer electrolyte membrane, the membrane electrode assembly and the polymer electrolyte fuel cell of the present invention are characterized by using such a polymer electrolyte material.

（式（Ｐ６）〜（Ｐ８）中、Ｚ _１ はＨ、アルキル基およびアリール基から選ばれた基、Ｚ _２ は直接結合、メチレン基、−ＣＯ−、−ＳＯ _２ −、ＯおよびＳから選ばれた基、Ｚ _３ は−ＣＯ−または−ＳＯ _２ −から選ばれた基、Ｚ _４ はＯ、ＳおよびＮＲ _Ｎ （Ｒ _Ｎ は任意の有機基）から選ばれた基を表す。式（Ｐ６）〜（Ｐ８）で表される基は任意に置換されていてもよい。） (In the formulas (P1) and (A1), X ₁ is a group selected from a direct bond and a divalent organic group, Q ₁ and Q ₂ are groups selected from a perfluoroalkyl group and a —CN group, Ar ₁ Represents an arbitrary divalent organic group containing an aromatic ring, and q ₁ and q ₂ are integers of 1 to 4. The groups represented by the formulas (P and (A1) may be optionally substituted. .)

(In the formulas (P6) to (P8), Z ₁ is a group selected from H, an alkyl group, and an aryl group, Z ₂ is a direct bond, a methylene group, —CO—, —SO ₂ —, O, and S. Z ₃ represents a group selected from —CO— or —SO ₂ —, Z ₄ represents a group selected from O, S and NR _N ( _RN is an arbitrary organic group). ) To (P8) may be optionally substituted.)

  According to the present invention, the high proton conductivity and the low fuel crossover are compatible, the hot water resistance, the hot methanol resistance, and the radical resistance are excellent, and the practicality capable of achieving the high output and the high energy capacity is excellent. A polymer electrolyte material, and a high-performance polymer electrolyte membrane, a membrane electrode assembly and a polymer electrolyte fuel cell using the same can be provided.

  Hereinafter, the present invention will be described in detail.

The present invention is compatible with the above-mentioned problems, that is, high proton conductivity and low fuel crossover, and is excellent in hot water resistance, heat resistance methanol resistance and durability, and in addition to high output and high energy when used as a polymer electrolyte fuel cell. The chemical structure of the polymer electrolyte material capable of achieving the density is intensively studied, and an aromatic polyether polymer having at least the structural units represented by the following general formula (P1) and the following general formula (A1) is obtained. wherein, aromatic polyether-based polymer possess an ionic group, a Q ₁ and Q ₂ is a perfluoroalkyl group, Ar ₁ is Ru is selected from the following general formula (P6) ~ (P8) polymer It has been clarified that when an electrolyte material is used, this problem can be solved at once.

（式（Ｐ６）〜（Ｐ８）中、Ｚ _１ はＨ、アルキル基およびアリール基から選ばれた基、Ｚ _２ は直接結合、メチレン基、−ＣＯ−、−ＳＯ _２ −、ＯおよびＳから選ばれた基、Ｚ _３ は−ＣＯ−または−ＳＯ _２ −から選ばれた基、Ｚ _４ はＯ、ＳおよびＮＲ _Ｎ （Ｒ _Ｎ は任意の有機基）から選ばれた基を表す。式（Ｐ６）〜（Ｐ８）で表される基は任意に置換されていてもよい。）
従来のスルホン化芳香族ポリエーテルケトン、スルホン化芳香族ポリエーテルスルホンを高分子電解質材料として用いた場合には、プロトン伝導性を高めるためにイオン性基の含有量を増加すると、高分子電解質材料が膨潤し、内部に大きな水のクラスターができ易く、高分子電解質材料中にいわゆる自由水が多くなる。かかる自由水中には、メタノールなどの燃料の移動が容易に行なわれるためメタノールなどの燃料クロスオーバーを抑制することは困難であった。さらに、これらのポリマーは主鎖中にラジカル耐性に劣るケトン基やスルホン基を多量に含むため燃料電池発電中に要求されるラジカル耐性にも問題があった。 (In the formulas (P1) and (A1), X ₁ is a group selected from a direct bond and a divalent organic group, Q ₁ and Q ₂ are groups selected from a perfluoroalkyl group and a —CN group, Ar ₁ Represents any divalent organic group containing an aromatic ring, and q ₁ and q ₂ are integers of 1 to 4. The groups represented by formulas (P1) and (A1) may be optionally substituted. Good.)

(In the formulas (P6) to (P8), Z ₁ is a group selected from H, an alkyl group, and an aryl group, Z ₂ is a direct bond, a methylene group, —CO—, —SO ₂ —, O, and S. Z ₃ represents a group selected from —CO— or —SO ₂ —, Z ₄ represents a group selected from O, S and NR _N ( _RN is an arbitrary organic group). ) To (P8) may be optionally substituted.)
When the conventional sulfonated aromatic polyether ketone or sulfonated aromatic polyethersulfone is used as the polymer electrolyte material, the polymer electrolyte material can be increased by increasing the content of ionic groups in order to increase proton conductivity. Swells, and a large cluster of water is easily formed in the interior, and so-called free water increases in the polymer electrolyte material. In such free water, it is difficult to suppress fuel crossover such as methanol because fuel such as methanol easily moves. Further, since these polymers contain a large amount of ketone groups and sulfone groups inferior in radical resistance in the main chain, there is a problem in radical resistance required during fuel cell power generation.

The polyelectrolyte material of the present invention has a relatively hydrophilic and allyophilic polar group that an aromatic polyether polymer such as sulfonated aromatic polyetherketone and sulfonated aromatic polyethersulfone had. That is, because it does not have a ketone group (—CO—) or a sulfone group (—SO ₂ —), or the amount thereof is small, it is dimensionally stable in hot water at high temperatures and aqueous fuel such as methanol. It has excellent characteristics and is effective in achieving both high proton conductivity and suppression of fuel crossover. Furthermore, the present inventors have also found that radical resistance is remarkably improved by removing these hydrophilic polar groups.

  The polymer electrolyte material of the present invention includes an aromatic polyether polymer having structural units represented by the following general formula (P1) and the following general formula (A1), and the aromatic polyether polymer is ionic. It is necessary to have a group.

(In the formulas (P1) and (A1), X ₁ is a group selected from a direct bond and a divalent organic group, Q ₁ and Q ₂ are perfluoroalkyl groups , and Ar ₁ is an arbitrary group containing an aromatic ring. Represents a divalent organic group, and q ₁ and q ₂ are integers of 1 to 4. The groups represented by the formulas (P1) and (A1) may be optionally substituted.)
In the present invention, the perfluoroalkyl group means a group in which most or all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms. In the present invention, a group in which 85% or more of hydrogen atoms in an alkyl group are substituted with fluorine atoms is defined as a perfluoroalkyl group. In the present invention, the perfluoroalkyl group is not necessarily composed only of carbon and hydrogen and / or fluorine, and may contain other atoms such as oxygen, sulfur and nitrogen as long as the object of the present invention is not impaired. There is no problem. However, from the viewpoint of radical resistance, heat resistance methanol resistance, and fuel crossover suppression effect, the perfluoroalkyl group is more preferably composed only of carbon and hydrogen and / or fluorine, and more preferably from carbon and fluorine. It consists of only. Among these, a lower perfluoroalkyl group having 1 to 6 carbon atoms is more preferable from the viewpoint of heat resistance methanol resistance, and particularly preferable specific examples include CF ₃ group, CF ₃ CF ₂ group, CF ₃ CF ₂ CF _2. In addition to a group and a (CF ₃ ) ₂ CF group, a CF ₃ CF ₂ OCF ₂ CF ₂ group, a CF ₃ CF ₂ SCF ₂ CF ₂ group, and the like can be given. Of these, CF ₃ group and CF ₃ CF ₂ group are most preferable from the viewpoint of heat resistance methanol resistance and availability of raw materials.

  In the polymer electrolyte material of the present invention, the content of the structural unit represented by the general formula (P1) is a structural unit based on the structural unit represented by the general formula (P1) and other repeating units. It is preferable that the structural unit represented by the general formula (P1) is contained in an amount of 10 mol% or more, more preferably 30 mol% or more. When the structural unit represented by the general formula (P1) is contained in less than 10 mol%, the fuel crossover suppressing effect, the hot water resistance, and the heat resistant methanol property may be insufficient.

Further, the group Q ₁ and Q ₂ in the general formula (P1), radical resistance, heat methanolic, points or Lapa perfluoroalkyl group of fuel crossover suppressing effect is used.

  In the present invention, the aromatic polyether polymer may contain an aromatic polyether other than those represented by formulas (P1) and (A1) as a constituent unit. An aromatic polyether refers to a polymer mainly composed of aromatic rings, which contains 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.

  As the polymer electrolyte material of the present invention, the general formula (P1) is more preferably the following general formula (P2) from the viewpoint of the fuel crossover suppressing effect, the availability of raw materials, and the polymer high molecular weight.

(In Formula (P2), X ₁ represents a group selected from a direct bond and a divalent organic group. The group represented by Formula (P2) 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, the aromatic polyether polymer represented by the general formula (P1) uses, for example, the following general formula (P1-1) as an aromatic active dihalide compound, and is aromatic with a dihydric phenol compound. It can be synthesized by a nucleophilic substitution reaction.

(In Formula (P1-1), L ₁ and L ₂ are halogen atoms, X ₁ is a group selected from a direct bond and a divalent organic group, Q ₁ and Q ₂ are a perfluoroalkyl group and a —CN group. Represents a selected group, and q ₁ and q ₂ are integers of 1 to 4. The group represented by the formula (P1-1) may be optionally substituted.)
The aromatic active dihalide compound needs to include those represented by the general formula (P1-1), but other compounds may be used in combination. Specific examples of the aromatic active dihalide compound to be copolymerized include 4,4′-dichlorodiphenyl sulfone, 4,4′-difluorodiphenyl sulfone, 4,4′-dichlorodiphenyl ketone, and 4,4′-difluoro. Examples thereof include diphenyl ketone, 4,4′-dichlorodiphenylphenylphosphine oxide, 4,4′-difluorodiphenylphenylphosphine oxide, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile and the like. Among these, 4,4′-dichlorodiphenyl ketone and 4,4′-difluorodiphenyl ketone are more preferable as the copolymer component from the viewpoint of heat resistant methanol resistance and fuel crossover suppression effect.

Furthermore, the method for synthesizing the aromatic active dihalide compound represented by the formula (P1-1) is not particularly limited as long as it is a method capable of obtaining substantial purity. When X _{1 in} P1-1) is an aromatic ring, synthesis is performed using a Suzuki coupling reaction between an aromatic bisboric acid compound (Suzuki coupling reagent) containing X ₁ and an aromatic dihalide compound. Can do.

As X ₁ in the formula (P1-1), X ₁ may be at least one group selected from a direct bond, an alkylene group, and an arylene group. A direct bond or an arylene group is more preferable from the viewpoint of hot water resistance, hot methanol resistance, and fuel crossover suppression effect. In the specification of the present invention, the arylene group does not mean only a benzene compound, but also includes a heterocyclic compound such as a pyridine compound and a thiophene compound.

Preferable examples of the group X ₁ include a direct bond, a benzene-based organic group represented by the following formulas (X2-1) to (X2-21), and the following formulas (X2-22) to (X2-34). The organic group of the heterocyclic system shown by can be illustrated. However, the organic group X ₁ used in the present invention is not limited to these. In addition, these organic groups may have an ionic group or an arbitrary substituent. Two or more kinds of these organic groups can be contained in the polymer electrolyte material, and it may be preferable by combining them. Among these, the direct bond and the organic groups represented by the following formulas (X2-1) to (X2-5) and (X2-11) to (X2-13) have the effect of improving the hot water resistance and the hot methanol resistance. Therefore, an organic group represented by formulas (X2-1), (X2-4), (X2-5), (X2-12), and (X2-13) is more preferable. .

Further, examples of the group X _1, can be used most preferably those heat methanolic, fuel crossover suppressive effect, from the viewpoint of solubility is a group represented by the following general formula (P3) or (P4).

(The groups represented by the formulas (P3) and (P4) may be optionally substituted.)
The polymer electrolyte material of the present invention more preferably further has a structural unit represented by the following general formula (P5) together with the structural unit represented by the general formula (P1).

(In the formula (P5), Y ₁ is —CO—, —SO ₂ —, or —P (Rp) O— (Rp is an arbitrary organic group), M ¹ and M ² are hydrogen, a metal cation, an ammonium cation, a1 and a2 represent an integer of 1 to 4. The group represented by the formula (P5) may be optionally substituted.)
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 the monomer having a sulfonic acid group as an ionic group include a sulfonated product of the monomer represented by the formula (P1-1), 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone, 3,3′-disulfonate-4,4′-difluorodiphenyl sulfone, 3,3′-disulfonate-4,4′-dichlorodiphenyl ketone, 3,3′-disulfonate-4,4′-difluorodiphenyl ketone 3,3′-disulfonate-4,4′-dichlorodiphenylphenylphosphine 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. . Of these, sulfonated monomers represented by the above formula (P1-1), 3,3′-disulfonate-4,4′-dichlorodiphenyl ketone, 3,3 from the viewpoint of heat resistance methanol resistance and fuel crossover suppression effect '-Disulfonate-4,4'-difluorodiphenyl ketone is more preferable, and the compound represented by the formula (P1-1) having a sulfonic acid group is most preferable. 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 addition, as the dihydric phenol compound used as a monomer in the present invention, various dihydric phenol compounds that can be used for polymerization of an aromatic polyether polymer by an aromatic nucleophilic substitution reaction can be used. It is not limited. In addition, those obtained by introducing an ionic group into these aromatic dihydroxy compounds can also be used as monomers. 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.

The polymer electrolyte material of the present invention is represented by at least the following general formulas (P6) to (P8) as Ar ₁ in the general formula (A1) from the viewpoint of hot water resistance, hot methanol resistance, and fuel crossover suppression effect. that that having a least one member selected from the group.

(In the formulas (P6) to (P8), Z ₁ is a group selected from H, an alkyl group, and an aryl group, Z ₂ is a direct bond, a methylene group, —CO—, —SO ₂ —, O, and S. Z ₃ represents —CO— or —SO ₂ —, Z ₄ represents O, S and NR _N ( _RN is an arbitrary organic group), groups represented by formulas (P6) to (P8) May be optionally substituted.)
Among them, it is most preferable that Ar ₁ is represented by the formula (6) and the Z ₁ is a phenyl group, or Ar ₁ is represented by the formula (7) and the Z ₂ is a direct bond. preferable.

Specific examples of Ar ₁ include a phenylene group, a naphthylene group, and organic groups represented by the following general formulas (Ar1-1) to (Ar1-16). These may have a substituent. Among these, the organic groups represented by the general formulas (Ar1-6) to (Ar1-13) are particularly preferable because they have a large fuel permeation suppressing effect and are effective in improving dimensional stability in fuel. molecular electrolyte material preferably contains at least one of the organic groups represented by the general formula as _{Z 2 (Ar1-6) ~ (Ar1-13} ). Among the organic groups represented by the general formulas (Ar1-6) to (Ar1-13), the organic groups represented by the general formula (Ar1-7) and the general formula (Ar1-8) are particularly preferable. Is an organic group represented by the general formula (Ar1-7).

  In the polymerization by the aromatic nucleophilic substitution reaction in the present invention, a polymer can be obtained by reacting the monomer mixture in the presence of a basic compound. 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. Examples of the solvent that can be used include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, diphenyl sulfone, sulfolane, and the like. And any solvent that can be used as a stable solvent in the aromatic nucleophilic substitution reaction. 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. 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, the polymer can be obtained by precipitating the polymer as a solid by adding the reaction solution in a solvent having low polymer solubility, and collecting the precipitate by filtration.

  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) [wherein 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 0.5 to 3.0 mmol / g in terms of proton conductivity, fuel crossover and mechanical strength, and most preferably in terms of fuel crossover. Is 0.7-1.5 mmol / g. When the sulfonic acid group density is lower than 0.5 mmol / g, sufficient proton generation characteristics may not be obtained due to low proton conductivity. When the sulfonic acid group density is higher than 3.0 mmol / g, it may be used as an electrolyte membrane for a fuel cell. In addition, sufficient hot 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 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 ion exchange capacity is obtained by the following formula.

Ion exchange capacity (meq / g) =
[Concentration of sodium hydroxide aqueous solution (mmol / ml) × Drip amount (ml)] / Dry weight of sample (g)
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 in, for example, Journal of Membrane Science, 197 (2002) 231-242.

  The method for introducing an ionic group in a polymer reaction will be described with an example. The introduction of a phosphonic acid group into an aromatic polymer is described in, for example, Polymer Preprints, Japan, 51, 750 (2002) Is possible. 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. However, the polymer electrolyte material of the present invention is not limited to a membrane shape, and the shape is not limited to the above-mentioned membrane shape, but can be used such as a plate shape, a fiber shape, a hollow fiber shape, a particle shape, and a lump shape. Can take various forms. 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 is possible. In the former, for example, a method of forming a film by dissolving the polymer electrolyte material in a solvent such as N, N-dimethylacetamide, casting the solution on a glass plate or the like, and removing the solvent is exemplified. it can.

  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.

  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. 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 around 1 hour. If the heat treatment temperature is too low, the effect of suppressing fuel permeability is 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 effect of suppressing fuel permeability 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 cutoff.

  In the polymer electrolyte membrane of the present invention, the polymer structure can be further cross-linked by means such as radiation irradiation as 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, an additive such as a plasticizer, a stabilizer, or a mold release agent used for a general polymer compound may be added to the polymer electrolyte material of the present invention within a range not contrary to the object of the present invention. it can.

  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.

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.

  There are no particular limitations on the method of joining the polymer electrolyte material and the electrode when such a polymer electrolyte material is used as a fuel cell, and known methods (for example, the chemical plating method described in Electrochemistry, 1985, 53, 269. Electrochem. Soc .: Electrochemical Science and Technology, 1988, 135 (9), 2209. can be applied.

  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. 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.

  Furthermore, the application of the polymer electrolyte fuel cell of the present invention is not particularly limited, but a power supply source for a mobile body is preferable. In particular, it is preferably used as a power supply source for mobile devices such as mobile devices such as mobile phones, personal computers and PDAs, household appliances such as vacuum cleaners, automobiles such as passenger cars, buses and trucks, ships, and railways.

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

(1) Sulfonic Acid Group Density A film-like sample serving as a specimen was immersed in pure water at 25 ° C. for 24 hours, vacuum-dried at 40 ° C. for 24 hours, and 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-like sample in a 30 wt% methanol aqueous solution at 25 ° C for 24 hours, the membrane sample is taken out in an atmosphere of 25 ° C and relative humidity of 50-80%, and protons are obtained as quickly as possible by the constant potential AC impedance method. Conductivity was measured.

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) Methanol Permeation A film-like sample was immersed in a 30 wt% methanol aqueous solution at 60 ° C. for 24 hours, and then measured at 20 ° C. using a 30 wt% methanol aqueous solution. Since the amount of methanol permeation greatly changes before and after being immersed in a 30 wt% methanol aqueous solution at 60 ° C. for 24 hours, this pretreatment must be performed in order to evaluate the accurate characteristics of the membrane.

A sample membrane was sandwiched between the H-type cells, pure water (60 mL) was placed in one cell, and 30 wt% 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.

(4) 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.

(5) 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 shape having a length of about 5 cm and a width of about 1 cm, immersed in water at 25 ° C. for 24 hours, and then the length (L1) was accurately 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 accurately measured again with calipers, and the dimensional change rate was calculated by the following formula (S1).

(Dimensional change rate in 30 wt% methanol aqueous solution) = L2 / L1 (S1)
L1: length of the electrolyte membrane after being immersed in water at 25 ° C. for 24 hours (cm)
L2: length of the electrolyte membrane after being immersed in a 30 wt% methanol aqueous solution at 60 ° C. for 12 hours (cm)
(6) Film thickness It measured using Mitutoyo ID-C112 type | mold set to Mitutoyo granite comparator stand BSG-20.

Synthesis example 1
Synthesis of difluoro monomer represented by the following formula (G1)

  Grignard reagent was prepared from 110 g of 5-bromo-2-fluorobenztrifluoride and Mg and reacted with B (OMe) 3 in an acetone / dry ice bath. 4-Fluoro-3-trifluoromethylphenylboric acid was synthesized by hydrolysis with HClaq and extraction with water. Next, in the presence of Na 2 CO 3 and Pd (PPh) 4, 67 g of the obtained 4-fluoro-3-trifluoromethylphenyl boric acid and 31 g of p-dibromobenzene were reacted for 2 h in a toluene / water solvent. After extraction with water, the catalyst was removed with a short column (Florisil) and recrystallized to obtain a difluoro monomer represented by the above formula (G1).

Synthesis example 2
Synthesis of a sulfonated difluoro monomer represented by the following formula (G2)

  30 g of the difluoro monomer represented by the formula (G1) was reacted in 100 mL of concentrated sulfuric acid at 100 ° C. for 10 hours. Thereafter, it was poured little by little into a large amount of water and neutralized with NaOH, and then sodium chloride was added to precipitate the composite. The resulting precipitate was filtered off and recrystallized with an aqueous ethanol solution to obtain a sulfonated difluoro monomer represented by the above formula (G2).

Synthesis example 3
Synthesis of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone represented by the following formula (G3)

  109.1 g of 4,4′-difluorobenzophenone was reacted at 150 ° C. for 10 hours in 150 mL of fuming sulfuric acid (50% SO 3). Thereafter, the mixture was poured little by little into a large amount of water, neutralized with NaOH, and 200 g of sodium chloride was added to precipitate the composite. The resulting precipitate was filtered off and recrystallized with an aqueous ethanol solution to obtain disodium 3,3'-disulfonate-4,4'-difluorobenzophenone represented by the above formula (G3).

  Synthesis example 4

  A difluoro monomer represented by the above formula (G4) was obtained by the method described in Synthesis Example 1 except that 63 g of 9,9-bis (4-bromophenyl) fluorene was used instead of 31 g of p-dibromobenzene.

  Synthesis example 5

  A difluoro monomer represented by the above formula (G5) was obtained by the method described in Synthesis Example 1 except that 63 g of 4,4′-dibromotetraphenylmethane was used instead of 31 g of p-dibromobenzene.

Example 1
Synthesis of a polymer represented by the following formula (J1)

(In the formula, * represents that the right end of the upper formula and the left end of the lower formula are connected at that position.)
Using 3.5 g of potassium carbonate, 7.1 g of 4,4′-dihydroxytetraphenylmethane, 1.6 g of the difluoro monomer obtained in Synthesis Example 1 and 8.1 g of the sulfonated difluoro monomer obtained in Synthesis Example 2 Polymerization was carried out at 190 ° C. in N-methylpyrrolidone (NMP). Purification was carried out by reprecipitation with a large amount of water to obtain a polymer represented by the above formula (G4). The resulting polymer had a sulfonic acid group density after proton substitution of 1.0 mmol / g and a weight average molecular weight of 220,000.

  A 25 wt% N-methylpyrrolidone (NMP) solution in which the obtained polymer was dissolved was cast-coated on a glass substrate, dried at 100 ° C. for 4 hours, and then heat-treated at 325 ° C. for 10 minutes under nitrogen to obtain a polymer electrolyte. A membrane was obtained. After proton substitution by immersion in 1N hydrochloric acid at 25 ° C. for 24 hours, it was sufficiently washed by immersion in a large excess of pure water for 24 hours.

  The film obtained was 33 μm thick. The evaluation results are summarized in Table 1. While maintaining high proton conductivity, the effect of suppressing methanol crossover was great. Moreover, it was excellent in heat-resistant methanol property.

Example 2
Synthesis of a polymer represented by the following formula (J2)

(In the formula, * represents that the right end of the upper formula and the left end of the lower formula are connected at that position.)
3.5 g of potassium carbonate, 7.1 g of 4,4′-dihydroxytetraphenylmethane, 5.6 g of the difluoro monomer obtained in Synthesis Example 1, and disodium 3,3′-disulfonate-4 obtained in Synthesis Example 3 Polymerization was carried out at 190 ° C. in N-methylpyrrolidone (NMP) using 2.7 g of 4,4′-difluorobenzophenone. Purification was carried out by reprecipitation with a large amount of water to obtain a polymer represented by the above formula (G5). The resulting polymer had a sulfonic acid group density after proton substitution of 1.0 mmol / g and a weight average molecular weight of 240,000.

  A film was prepared by the method described in Example 1 except that the polymer of formula (J1) obtained in Example 1 was changed to the polymer of formula (J2).

  The obtained film was 35 μm thick. The evaluation results are summarized in Table 1. While maintaining high proton conductivity, the effect of suppressing methanol crossover was great. Moreover, it was excellent in heat-resistant methanol property.

Example 3
Synthesis of a polymer represented by the following formula (J3)

(In the formula, * represents that the right end of the upper formula and the left end of the lower formula are connected at that position.)
5.6 g of the difluoro monomer obtained in Synthesis Example 1 and 2.7 g of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 3 were used as the difluoro monomer obtained in Synthesis Example 4. The polymer was synthesized by the method described in Example 2 except that 6.4 g and disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 3 were changed to 4.2 g. . The resulting polymer had a sulfonic acid group density after proton substitution of 1.2 mmol / g and a weight average molecular weight of 180,000.

  A film was prepared by the method described in Example 1 except that the polymer of the formula (J1) obtained in Example 1 was changed to the polymer of the formula (J3).

  The obtained film was 40 μm thick. The evaluation results are summarized in Table 1. While maintaining high proton conductivity, the effect of suppressing methanol crossover was great. Moreover, it was excellent in heat-resistant methanol property.

Example 4
Synthesis of a polymer represented by the following formula (J4)

(In the formula, * represents that the right end of the upper formula and the left end of the lower formula are connected at that position.)
5.6 g of the difluoro monomer obtained in Synthesis Example 1 and 2.7 g of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 3 were used as the difluoro monomer obtained in Synthesis Example 5. The polymer was synthesized by the method described in Example 2 except that 6.4 g and disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 3 were changed to 4.2 g. . The resulting polymer had a sulfonic acid group density after proton substitution of 1.2 mmol / g and a weight average molecular weight of 190,000.

  A film was prepared by the method described in Example 1 except that the polymer of formula (J1) obtained in Example 1 was changed to the polymer of formula (J4).

  The obtained film was 41 μm thick. The evaluation results are summarized in Table 1. While maintaining high proton conductivity, the effect of suppressing methanol crossover was great. Moreover, it was excellent in heat-resistant methanol property.

Comparative Example 1
A commercially available Nafion (R) 117 membrane (manufactured by DuPont) was used to evaluate ion conductivity, MCO, and heat resistance methanol resistance. The Nafion (R) 117 membrane was immersed in 5% hydrogen peroxide water at 100 ° C. for 30 minutes, and then 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.

  Comparative Example 2

(In the formula, * represents that the right end of the upper formula and the left end of the lower formula are connected at that position.)
The polyethersulfone of the above formula (J5) was synthesized in the same manner as in the method described in U.S. Pat. The sulfonic acid group density of the H-type polymer was 1.3 mmol / g, and the weight average molecular weight was 160,000.

  The film was formed by the method described in Example 1 except that the polymer of the formula (J1) obtained in Example 1 was changed to the polymer of the formula (J5) and that the heat treatment was not performed at 325 ° C. for 10 minutes under nitrogen. Was made.

  The obtained film was 35 μm thick. The evaluation results are summarized in Table 1. There was not much suppression effect of methanol crossover. Moreover, heat-resistant methanol property was insufficient.

  Each evaluation result of Examples 1-2 and Comparative Examples 1-2 is shown in Table 1. The membranes of Examples 1 and 2 had a greater effect of suppressing methanol crossover than the Nafion (R) 117 membrane of Comparative Example 1, and were excellent in heat-resistant methanol resistance. Further, although having the same level of sulfonic acid group as compared with the membrane of Comparative Example 2, the effect of suppressing methanol crossover was great and the heat resistant methanol resistance was also excellent.

  The electrolyte membrane of the present invention can be applied to various electrochemical devices (for example, a fuel cell, a water electrolysis device, a chloroalkali electrolysis device, 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 (12)

They include aromatic polyether polymer having a structural unit represented by at least the following general formulas (P1) and the following general formula (A1), aromatic polyether-based polymer possess an ionic group, Q ₁ and _{Q 2} is a perfluoroalkyl group, polymer electrolyte materials Ar ₁ is wherein Rukoto selected from the following general formula (P6) ~ (P8).

(In the formulas (P1) and (A1), X ₁ is a group selected from a direct bond and a divalent organic group, Q ₁ and Q ₂ are perfluoroalkyl groups , and Ar ₁ is an arbitrary group containing an aromatic ring. Represents a divalent organic group, and q ₁ and q ₂ are integers of 1 to 4. The groups represented by the formulas (P1) and (A1) may be optionally substituted.)

(In the formulas (P6) to (P8), Z ₁ is a group selected from H, an alkyl group, and an aryl group, Z ₂ is a direct bond, a methylene group, —CO—, —SO ₂ —, O, and S. Z ₃ represents a group selected from —CO— or —SO ₂ —, Z ₄ represents a group selected from O, S and NR _N ( _RN is an arbitrary organic group). ) To (P8) may be optionally substituted.) 2. The polymer electrolyte material according to claim 1 , wherein the general formula (P1) is the following general formula (P2).

(In Formula (P2), X ₁ represents a group selected from a direct bond and a divalent organic group. The group represented by Formula (P2) may be optionally substituted.) Polymer electrolyte material according to claim 2, characterized in that X ₁ is selected from the following general formula (P3) or (P4).

(The groups represented by the formulas (P3) and (P4) may be optionally substituted.) The polymer electrolyte material according to any one of claims 1 to 3 , further comprising the aromatic polyether polymer having a structural unit represented by the following general formula (P5).

(In Formula (P5), Y ₁ represents —CO—, —SO ₂ —, or —P (Rp) O— (Rp represents an arbitrary organic group), and M ¹ and M ² represent hydrogen, a metal cation, and ammonium. Represents a cation, and a1 and a2 each represent an integer of 1 to 4. The group represented by the formula (P5) may be optionally substituted. The polymer electrolyte material according to claim 1, wherein Ar ₁ is selected from the formula (P6) or (P7), Z ₁ is a phenyl group, and Z ₂ is a direct bond. . The ionic group is a sulfonic acid group, a sulfonimide group, sulfuric acid group, phosphonic acid group, to any one of claims 1 to 5, 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 6 , wherein the ionic group is a sulfonic acid group. The polymer electrolyte material according to claim 7 , wherein the sulfonic acid group density is 0.5 to 3.0 mmol / g. A polymer electrolyte membrane comprising the polymer electrolyte material according to any one of claims 1 to 8 . A membrane electrode assembly comprising the polymer electrolyte material and / or polymer electrolyte membrane according to any one of claims 1 to 9 . A polymer electrolyte fuel cell comprising the polymer electrolyte material and / or polymer electrolyte membrane and / or membrane electrode assembly according to any one of claims 1 to 10 . Polymer electrolyte fuel cell, an organic compound having 1 to 6 carbon atoms, and that in claim 11, 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.