JP2003022709A - Blended polymer electrolyte, electrolytic membrane having the electrolyte as main component, and membrane /electrode junction containing the electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyelectrolyte superior in ionic conductivity and durability and suitable for a proton exchange membrane or the like of a fuel cell, and provide an electrolyic membrane having the electrolyte as the main component, and a membrane/electrode junction containing the electrolyte. SOLUTION: This is a blended polymer electrolyte composed of a mixture of (a) polybenzoxazole or polybenzthiazole having not less than one kind of groups selected from a sulfonic acid group and its salts or a phosphonic acid group and its salts, and (b) a basic polymer having at least one kind of groups selected from groups composed of a sulfonic acid group and its salts, a phosphonic acid group and its salts, and a carboxylic acid group and its salts.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polymer electrolyte useful as a polymer electrolyte membrane, an electrolyte membrane containing the polymer electrolyte as a main component, and a membrane / electrode assembly using the electrolyte.

[0002]

2. Description of the Related Art As an example of an electrochemical device using a solid polymer electrolyte as an ionic conductor instead of a liquid electrolyte, a water electrolysis cell or a fuel cell can be mentioned. The polymer membranes used for these must be sufficiently stable chemically, thermally, electrochemically and mechanically as a cation exchange membrane together with proton conductivity. Therefore, as a material that can be used for a long period of time, a perfluorocarbon sulfonic acid membrane typified by "Nafion (registered trademark)" manufactured by DuPont, USA has been mainly used. However, when it is attempted to operate at a temperature exceeding 100 ° C., the water content of the membrane drops sharply and the membrane softens significantly. Therefore, in a fuel cell using methanol, which is expected in the future, the performance of the fuel cell deteriorates due to permeation of methanol in the membrane, and the fuel cell cannot exhibit sufficient performance. Also,
It is pointed out that the cost of the membrane is too high even in the fuel cell which is operated mainly at 80 ° C. using hydrogen as a fuel, which is currently being studied, as an obstacle to the establishment of the fuel cell technology.

As an electrolyte membrane replacing the perfluorocarbon sulfonic acid membrane, a so-called hydrocarbon-based polymer electrolyte in which an acidic group such as a sulfonic acid group is introduced into a polymer such as polyetheretherketone, polyethersulfone, or polysulfone has been actively studied in recent years. ing. However, the hydrocarbon-based polymer electrolyte is more liable to hydrate and swell than perfluorocarbon sulfonic acid, and has a problem in durability under high humidity.

Mixing with a basic polymer is carried out as one of the measures for suppressing swelling. This is intended to suppress swelling by crosslinking an acidic group such as a sulfonic acid group in a polymer electrolyte with a basic polymer. For example, a mixture of polyethersulfone having a sulfonic acid group or polyetheretherketone having a sulfonic acid group (acidic polymer) and polybenzimidazole (basic polymer) (International Publication WO99 / WO99).
/ 54389). However, the sulfonated polyether sulfone and the sulfonated polyether ether ketone are insufficient in durability because the sulfonic acid group is likely to be removed by an acid or heat.

On the other hand, International Patent Publication WO 01/01
In JP 510, 2,5-difluoro-3,6-disulfoterephthalic acid and 2,2′-disulfo-4,4′-
Membranes composed of a mixture of polybenzazole and polybenzimidazole with diphenyletherdicarboxylic acid are described, but their ionic conductivity is not.

US Pat. No. 5,998,550 discloses a molecular complex of polybenzimidazole having a sulfonic acid group and a basic thermosetting compound, and US Pat.
No. 5439 discloses a molecular complex of polybenzimidazole having a sulfonic acid group and a basic thermoplastic polymer,
Although they are described respectively, none of them mentions electrochemical applications such as electrolytes.
Further, polybenzimidazole having a sulfonic acid group has a drawback that it has lower ionic conductivity than other polymer electrolytes such as perfluorocarbon sulfonic acid, polysulfone having a sulfonic acid group, polyether sulfone, and polyether ether ketone. It was

Generally, the durability is improved by mixing the basic polymer with the acidic polymer, but at the same time, the ion conductivity originally possessed by the acidic polymer is sacrificed.

[0008]

An object of the present invention is to provide a polymer electrolyte having excellent ionic conductivity and durability, which is suitable for a proton exchange membrane of a fuel cell, an electrolyte membrane containing the electrolyte as a main component, and It is to provide a membrane / electrode assembly containing the electrolyte.

[0009]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the inventors of the present invention mixed polybenzoxazole or polybenzthiazole having an acidic group with a basic polymer having an acidic group. By doing so, it was found that a polymer electrolyte, an electrolyte membrane, and a membrane / electrode assembly having excellent performances such as durability and ionic conductivity can be obtained, and the present invention has been completed.

That is, the present invention provides (1) a polybenzoxazole having at least one group selected from the group consisting of (a) a sulfonic acid group and a salt thereof, or a phosphonic acid group and a salt of Su. Or a basic polymer having polybenzthiazole and one or more groups selected from the group consisting of (b) sulfonic acid groups and salts thereof, phosphonic acid groups and salts thereof, carboxylic acid groups and salts thereof in the molecule. A blended polymer electrolyte consisting of a mixture with. (2) Polybenzoxazole or polybenzthiazole is represented by the following general formula (1) or (5);

[Chemical 6] [Formula (1) represents that the repeating unit consisting of Ar ¹ and Ar ² and the repeating unit consisting of Ar ³ and Ar ⁴ are linked randomly or in a block. In the formula, Ar
¹ and Ar ³ are the following general formula (2);

[Chemical 7] Represents one or more residues selected from the residues represented by
r ¹ and Ar ³ may be the same or different. X ¹
And X ² represents O or S. Y is O, S, C = O, CH
Represents any one of 2, C (CH ₃ ) ₂ , C (CF ₃ ), and S (═O) ₂ . Ar ² is the following general formula (3):

[Chemical 8] Represents one or more residues selected from the group represented by. Ar
⁴ is the following general formula (4);

[Chemical 9] Represents one or more residues selected from the group consisting of residues represented by. n ¹ is an integer of ¹ to 10000, m ¹ is 0 to 10
Represents an integer of 000. ]

[Chemical 10] [Formula (5) represents that each repeating unit is connected at random or in a block. In the formula, X ³ and X ⁴ represent either an S atom or an O atom, and these may be the same or different. Z is a SO ₃ H group,
It represents one or more groups selected from PO ₃ H ₂ groups and salts thereof. q represents an integer of 1 to 3, n ² represents an integer of 1 to 10000, and m ² represents an integer of 0 to 10000. ] The blend polymer electrolyte according to (1), and (3) the basic polymer is a polymer of 2-vinylpyridine and a copolymer thereof, 4-vinylpyridine. The blend polymer electrolyte according to (1) or (2), which is one or more compounds selected from the group consisting of a copolymer thereof, polybenzimidazole, polyquinoline, and polyquinoxaline. (4) An electrolyte membrane containing the blend polymer electrolyte according to any one of (1) to 3 as a main component, and (5) the blend polymer electrolyte membrane according to any one of (1) to (3). , A membrane and / or electrode layer, and a membrane / electrode assembly.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. Preferred examples of Ar ¹ and Ar ³ in the general formula (1) include the following (1a) to (1x);

[Chemical 11] However, the present invention is not limited to this. More preferred are (1b), (1c), (1e), (1f),
(1g) and (1i), most preferably (1
b) and (1c).

As the acidic group of Ar ² , a sulfonic acid group,
Mention may be made of phosphonic acid groups, carboxylic acid groups, and salts thereof. Of these, a sulfonic acid group and a phosphonic acid group are preferable, and a sulfonic acid group is more preferable because it enhances ion conductivity. As the compounds constituting the salt, sodium, potassium, magnesium, calcium, barium,
Metal ions such as aluminum, iron, titanium and copper, low molecular weight amines, imidazole compounds, pyridine derivatives,
Examples thereof include quinoline derivatives. The salts in all acidic groups are
It is preferably between 0 and 99 mol%, 20 mol%
It is more preferably at most, and even more preferably at most 10 mol%. The number of acidic groups may be one or more, but may be two or more. Different acidic groups such as sulfonic acid group and phosphonic acid may be mixed.

The aromatic group means a group containing at least one aromatic ring. The aromatic group may contain an alkyl group having 1 to 6 carbon atoms, a derivative thereof, or a hetero atom such as O or S. In that case, a substituent of the aromatic ring or a connection of the aromatic ring It is preferably present as a group that The aromatic ring includes not only hydrocarbon groups such as benzene ring and naphthalene ring but also aromatic heterocycles such as pyridine ring and quinoline ring. If a halogen element is covalently bonded to Ar ² , the environment is adversely affected at the time of disposal. Therefore, Ar ² preferably does not contain a halogen element covalently bonded. The acidic group is preferably bonded to the aromatic ring directly or through another organic group such as an alkyl group. In order to suppress the elimination of the acidic group, it is preferable that the aromatic ring to which the acidic group is bound is not bound to an electron donating group such as an alkyl group, an ether group or an amino group. Although not particularly limited, preferred examples of Ar ² include groups represented by the following structures (2a) to (2d).

[Chemical 12] Among them, (2a) is more preferable.

Preferred examples of Ar ⁴ are the following residues (3a) to (3t);

[Chemical 13] However, the present invention is not limited to these. Among them, (3b), (3e), (3g), (3k),
(3m) is more preferable, and (3b) and (3m) are the most preferable.

It is more preferable that X ³ and X ⁴ be O, and it is most preferable that both are O in order to enhance the ionic conductivity. Z is preferably a sulfonic acid group or a salt thereof. It is more preferable that n ¹ and n ² are 10 or more, since the molded body shows preferable mechanical properties, and it is further preferable that n ¹ and n ² are 100 or more. Further, m1 and m2 may be arbitrary values, but m1 / n1 or m2 / n2 is 0.
It is more preferable if it is between 0.5 and 0.5, and it is more preferable if it is between 0 and 0.2.

Preferred examples of the acidic polymer in the present invention are shown below in (4a) to (4an), but the invention is not limited thereto.

[Chemical 14]

[0017]

[Chemical 15]

Of these, (4a), (4c), and
(4e) and (4g). These polymers can be synthesized by any known method. For example, bis (o
-Aminophenol) compound can be obtained by reacting a dicarboxylic acid having a sulfonic acid group or a phosphonic acid group with heating and stirring in a dehydrating solvent such as polyphosphoric acid. The obtained polymer can be separated and purified by a known method before use. These polymers are homopolymers (when m ¹ or m ² is 0), block copolymers,
It may be any of random copolymers and can be used depending on the purpose.

In the acidic polymer of the present invention, some of the sulfonic acid groups and phosphonic acid groups are metal ions such as sodium, potassium, magnesium, calcium, barium, aluminum, iron, titanium and copper, and low molecular weight amines. A salt may be formed with an imidazole compound, a pyridine derivative, a quinoline derivative, etc., but the ratio of the salt is 20.
It is preferably at most mol%, more preferably at most 10 mol%.

As the basic polymer having an acidic group in the present invention, any known basic polymer structure having an acidic group can be used. Examples include vinylamine and vinylsulfonic acid copolymers, vinylamine and vinylphosphonic acid copolymers, vinylamine and acrylic acid copolymers, sulfonated poly (4-vinylpyridine), 4-vinylpyridine and vinyl. Sulfonic acid copolymer, 4-vinylpyridine-vinylphosphonic acid copolymer, sulfonated poly (2-vinylpyridine), sulfonated polybenzimidazole, sulfonated polyquinoline, sulfonated polyquinoxaline, pyridine Examples include aromatic compounds having a ring, a quinoline ring, or a quinoxaline ring (polyether sulfone, polysulfone, polyether, polysulfide, polyketone, polyether ketone, polyether ether ketone), etc., and have a sulfone group. Polyben Imidazole, polyquinoline, polyquinoxaline is preferable. Preferred structures are shown below, but the invention is not limited thereto.

[0021]

[Chemical 16]

[0022]

[Chemical 17]

The basic polymer having such an acidic group can be synthesized by chemically modifying a known basic polymer, or can be synthesized by polymerization using a monomer having an acidic group. Examples of the former include sulfonation with chlorosulfuric acid, anhydrous sulfuric acid and fuming sulfuric acid,
By introducing a phosphonic acid group through chloromethylation with chloromethyl ether, polybenzimidazole, polyvinylpyridine, polyquinoline, a method of synthesizing from polyquinoxaline, or after polybenzimidazole is ionized with an alkali metal hydride, alkyl sultone, Examples thereof include a method of introducing a sulfonic acid group or a phosphonic acid group by reacting a halogenated alkylphosphonic acid derivative or a halogenated alkylsulfonic acid derivative. Examples of the latter method include 2-sulfoterephthalic acid, 2,5-dicarboxybenzenephosphonic acid, 2,5-disulfoterephthalic acid, 2,5-dicarboxy-1,4-benzenediphosphonic acid, and the like. Phosphoterephthalic acid, 4-sulfoisophthalic acid, 5-sulfoisophthalic acid, 4,6-disulfoisophthalic acid, 3,5-dicarboxybenzenephosphonic acid, 2,4-dicarboxybenzenephosphonic acid,
Sulfo or phosphoisophthalic acid such as 4,6-dicarboxy-1,3-benzenediphosphonic acid, bis (4-
Carboxy-3-sulfophenyl) sulfone, bis (4
-Carboxy-2-sulfophenyl) sulfone, bis (4-carboxy-3-sulfophenyl) ether, bis (4-carboxy-2-sulfophenyl) ether,
4,4'-dicarboxy-3,3'-disulfobenzphenone, bis (4-carboxy-2-sulfophenyl)
Methane, 2,2-bis (4-carboxy-2-sulfophenyl) propane, bis (4-carboxy-2-sulfophenyl) sulfide, 2,2-bis (4-carboxy-3-sulfophenyl) hexafluoropropane , 1,
5-disulfo-2,6-naphthalenedicarboxylic acid, 2-
Sulfo-1,4-naphthalenedicarboxylic acid, 4,8-disulfo-2,6-naphthalenedicarboxylic acid, 4,8-diphospho-2,6-naphthalenedicarboxylic acid, 6-phospho-1,4-naphthalenedicarboxylic acid, Examples of the method include synthesizing polybenzimidazole using an acidic group-containing dicarboxylic acid as a raw material.

The amount of the acidic group in the basic polymer having an acidic group can be any value, but is preferably 0.
It is in the range of 1 to 5.0 meq / g. More preferably, it is 1.0 to 3.0 meq / g. The molecular weight of the polybenzoxazole or polybenzthiazole having an acidic group and the basic polymer having an acidic group is 1000 to 10
It is preferably in the range of 000000, and 10,000
More preferably, it is in the range of 1,000,000. The molecular weight can be measured by any known method such as a gel partition chromatography method, an osmotic pressure method, a light scattering method, and a viscosity measuring method, but the viscosity measuring method is simple. As an example of the viscosity measurement method, the measurement of logarithmic viscosity is described in Examples.
In the case of rigid linear molecules such as the polymers (4a) and (5a), the logarithmic viscosity is in the range of 0.1 to 100.0, more preferably 1.0 to 50.0, and further preferably , 3.0 to 30.0. Polymer (4a
In the case of flexible molecules such as b) and (5q), the logarithmic viscosity is preferably in the range of 0.1 to 10.0, and is preferably 0.5.
It is more preferably in the range of 5.0. If the molecular weight of any of the polymers is too small, the durability and mechanical properties will deteriorate, and if the molecular weight is too large, the solution viscosity will increase and the processability will deteriorate.

The amount of the basic polymer having an acidic group with respect to the polybenzoxazole or polybenzthiazole having an acidic group can be any amount, but the number of moles of the acidic group of polybenzoxazole or polybenzthiazole is not limited. On the other hand, the number of moles of basic groups of the basic polymer having an acidic group is preferably between 10 and 100%, and when it is 20 to 50%, a polymer electrolyte excellent in durability and ion conductivity. Can be obtained. The molecular weight of the polybenzoxazole or polybenzthiazole having an acidic group and the basic polymer having an acidic group is preferably in the range of 1,000 to 10,000,000, more preferably in the range of 10,000 to 1,000,000. The molecular weight can be measured by any known method such as a gel partition chromatography method, an osmotic pressure method, a light scattering method, and a viscosity measuring method, but the viscosity measuring method is simple. As an example of the viscosity measurement method, the measurement of logarithmic viscosity is described in Examples. In the case of rigid linear molecules such as polymers (4a) and (5a), the logarithmic viscosity is 0.1-10.
It is preferably in the range of 0.0, and 1.0 to 50.0
Is more preferable, and the range of 3.0 to 30.0 is preferable. Polymer (4ab), (5
In the case of a flexible molecule such as q), the logarithmic viscosity is 0.1 to
It is preferably in the range of 10.0, more preferably in the range of 0.5 to 5.0. Both polymers are
If the molecular weight is too small, durability and mechanical properties will deteriorate,
If the molecular weight is too large, the solution viscosity will increase and the processability will deteriorate.

For mixing the amounts of the polybenzoxazole or polybenzthiazole having an acidic group and the basic polymer having an acidic group, any known method can be used. Both may be mixed in a solvent that dissolves them together, or one of them may be made into a salt and then the two may be mixed, and then the salt may be restored by an acid or alkali treatment. Both may be mixed in a solvent in the presence of a low-molecular acid or base.

The polymer electrolyte of the present invention is extruded from a mixed solution or an isolated polymer electrolyte and formed into a fiber or film by any method such as spinning, rolling or casting,
It can be used as a coating material or the like.
When molding, it is preferable to mold from a solution dissolved in an appropriate solvent. As the solvent to be dissolved, N, N-dimethylacetamide, N, N-dimethylformamide,
Dimethyl sulfoxide, N-methyl-2-pyrrolidone,
An aprotic polar solvent such as hexamethylphosphonamide and a strong acid such as polyphosphoric acid, methanesulfonic acid, sulfuric acid, and trifluoroacetic acid can be used, but are not limited thereto. A plurality of these solvents may be mixed and used within a possible range. Further, as a means for improving the solubility, a solvent obtained by adding a Lewis acid such as lithium bromide, lithium chloride or aluminum chloride to an organic solvent may be used. The polymer concentration in the solution is 0.1-30
It is preferably in the range of% by weight. If it is too low, moldability deteriorates, and if it is too high, workability deteriorates. It is preferably 0.5 to 5% by weight.

As a method for obtaining a molded product from a solution, a known method can be used. For example, the molded product of the ionic group-containing polymer can be obtained by removing the solvent by heating, drying under reduced pressure, immersion in a polymer non-solvent that is miscible with a solvent that dissolves the polymer, and the like. When the solvent is an organic solvent, it is preferable to distill off the solvent by heating or drying under reduced pressure. When the solvent is a strong acid, it is preferably immersed in water, methanol, acetone or the like. At this time, if necessary, it may be formed into a fiber or film in a form of being combined with another polymer. When combined with a polyazole-based polymer having excellent heat resistance and mechanical properties, it is convenient for good molding.

The preferred method of forming the polymer electrolyte membrane of the present invention is casting of a polymer electrolyte solution. The solvent can be removed from the cast solution as described above to obtain an electrolyte membrane. It is preferable that the solvent is removed by drying in terms of film uniformity. Further, in order to prevent decomposition and deterioration of the polymer and solvent, it is preferable to dry under reduced pressure at the lowest temperature possible. As the substrate to be cast, a glass plate, a Teflon (registered trademark) plate, or the like can be used. When the viscosity of the solution is high, heating the substrate or the solution and casting at a high temperature lowers the viscosity of the solution, so that the solution can be easily cast. The thickness of the solution used for casting is not particularly limited, but is preferably 10 to 1000 μm. If it is too thin, the form of the film cannot be maintained, and if it is too thick, a non-uniform film is likely to be formed. More preferably, it is 100 to 500 μm. A known method can be used for controlling the cast thickness of the solution.
For example, an applicator, a doctor blade, or the like may be used to make the thickness constant, or a glass petri dish or the like may be used to make the casting area constant to control the thickness by the amount or concentration of the solution. A more uniform film can be obtained from the cast solution by adjusting the removal rate of the solvent. For example, when heating, the evaporation rate can be lowered by lowering the temperature in the first step. When immersed in a non-solvent such as water, the coagulation rate of the polymer can be adjusted by leaving the solution in air or an inert gas for an appropriate time.

The film of the present invention can have any film thickness depending on the purpose, but it is preferably as thin as possible from the viewpoint of ion conductivity. Specifically, it is preferably 200 μm or less, more preferably 10 to 50 μm.

Since the polymer electrolyte of the present invention is excellent in ionic conductivity and durability, it is suitable for use as a proton exchange membrane for fuel cells and the like in the form of a film or a membrane. Furthermore, by using the polymer of the present invention as a main component, it can be used as a binder resin when producing a bonded body of the polymer electrolyte membrane of the present invention and an electrode. Since the membrane / electrode assembly using the polymer electrolyte membrane of the present invention has low internal resistance and high durability, it is possible to greatly improve the power generation efficiency and durability of the fuel cell.

In the solid polymer electrolyte membrane / electrode assembly of the present invention, the catalyst metal and the binder are hot-pressed onto the polymer electrolyte membrane, or the polymer electrolyte of the present invention is sprayed onto a commercially available gas diffusion electrode. It can be obtained by applying or permeating the polymer electrolyte membrane with the polymer electrolyte membrane sandwiched therebetween and bonded. In addition, Teflon, polypropylene, polyethylene,
A resin film such as polyethylene terephthalate is coated with a paste in which the polymer electrolyte of the present invention and a catalyst are uniformly dispersed in a solvent and laminated by repeating drying, and the polymer layer is sandwiched with the catalyst layer inside and hot pressed. It can also be joined. Further, it is also possible to apply a paste in which the polymer polymer electrolyte of the present invention and the catalyst are evenly dispersed in a solvent to the polymer electrolyte by brush, brush, applicator, spray, printing, etc., and then dry the solvent for bonding. . Further, an electrode material such as carbon paper and the polymer electrolyte membrane of the present invention may be joined with this paste. In these methods, the ionic group may be prepared in advance as an alkali metal salt such as Na, and then the original acid may be restored by an acid treatment after bonding. The concentration of the polymer electrolyte in the solution or paste is preferably 0.1 to 10% by weight. Alternatively, the catalyst can be directly bonded to the polymer electrolyte membrane by sputtering or the like.

The catalyst is made of a conductive material carrying fine particles of catalytic metal and may contain other components. The metal is a noble metal containing platinum as a main component, and may contain other metals such as rhodium, palladium, gold, silver, iridium, and ruthenium. The particle size of the catalyst is preferably in the range of 1 to 50 nm. The amount of catalyst with respect to the polymer electrolyte is preferably in the range of 50 to 1000%. Other components include polytetrafluoroethylene, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and a tetrafluoroethylene-hexafluoroethylene copolymer as a binder.

The hot pressing conditions can be selected appropriately depending on the material used, but the pressing temperature is 1
The pressure is preferably in the range of 0 to 300 ° C. and the pressing pressure is in the range of 1 to 10 MPa.

[0035]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Various measurements were performed as follows.

(Ion conductivity measurement) A platinum wire (diameter: 0.2 mm) was pressed against the surface of the strip-shaped film sample on a probe for self-made measurement (made of Teflon), and a constant temperature and constant humidity oven at 80 ° C and 95% RH was used. (Nagano Scientific Machinery Works, LH-
20-01) hold the sample in 10 KHz between the platinum wires
AC impedance in SOLARTRON 1
250FREQUENCY RESPONSE ANA
It was measured by LYSER. The measurement was performed while changing the distance between the electrodes, and the conductivity in which the contact resistance between the film and the platinum wire was canceled was calculated from the gradient obtained by plotting the distance between the electrodes and the measured resistance value by the following formula. -Polymer electrolyte membrane conductivity [S / cm] = 1 / membrane width [cm] x membrane thickness [cm]
× Gradient between resistance poles [Ω / cm] ・ Membrane / electrode assembly conductivity (S / cm) = film thickness (cm) / film resistance (Ω)
/ Electrode area (cm ² )

(Polymer logarithmic viscosity) Polymer concentration 0.0
The methanesulfonic acid solution of 5 g / dl was measured at 25 ° C. using an Ostwald viscometer.

(Water resistance test) Polymer electrolyte membrane 50 mg
Was enclosed in a glass ampoule together with 5 ml of ion-exchanged water. The ampoule was heated at 105 ° C for 3 days. After cooling, the ampoule was opened and the solid substance was collected by filtration with a 1G2 glass filter. The filter was dried under reduced pressure at 80 ° C. overnight, the weight of the solid content was determined from the weight before and after filtration, and the weight reduction rate was determined. Weight reduction rate [%] = residue weight [mg] / 50 × 100

(Quantification of Ionic Group) Polymer Electrolyte Membrane 1
00 mg was immersed in 50 ml of 0.01 N NaOH aqueous solution, and stirred overnight at 25 ° C. After that, 0.05N HC
1 neutralization titration with an aqueous solution. For the neutralization titration, a potentiometric titrator COMTITE-980 manufactured by Hiranuma Sangyo Co., Ltd. was used. The amount of ionic groups is calculated by the following formula. Ionic group content [meq / g] = (10-titration amount [m
l]) / 2

(Heat Resistance Evaluation) About 2 mg of the sample polymer was pre-dried at 100 ° C. for 10 minutes in an argon atmosphere using a thermogravimetric analyzer TGA-50 manufactured by Shimadzu Corporation, and then at a rate of 10 ° C./minute. The temperature was raised and measured. The temperature at the inflection point of the weight change curve was taken as the heat loss starting temperature.

Example 1 0.140 g of polybenzoxazole (4a) having an acidic group having m1 / n1 = 0 and an inherent viscosity of 5.3 dl / g, and an inherent viscosity of 1.2 dl / g.
A basic polymer (5ae) having an acidic group of 0.0
28 g, 0.06 g of triethylamine and 30 ml of dimethyl sulfoxide (hereinafter abbreviated as DMSO) at 60 ° C.
It was heated and stirred at to dissolve. The solution was filtered through a 1G2 glass filter, poured into a glass flat-bottomed dish having a diameter of 90 mm, and dried under reduced pressure at 40 ° C. for 2 days and then at 100 ° C. for 1 day to remove DMSO. The peeled film is
It was treated at room temperature in a 1N HCl aqueous solution with gentle stirring for 1 day. The membrane was washed with deionized water and treated in deionized water at 100 ° C. for 1 hour. After that, take out the film,
It was dried under a nitrogen stream. When the obtained membrane was immersed in ion-exchanged water at 25 ° C. for 1 day, the water absorption was 85% by weight based on the dry weight of the membrane. Table 1 shows various evaluation results of the film.

(Examples 2 to 16) Membranes were prepared and various evaluations were performed in the same procedure as in Example 1 except that the mixing ratio with the polymer was changed. The evaluation results are shown in Table 1.

(Example 17) 0.140 of acidic polymer (4a) having m1 / n1 = 0 and logarithmic viscosity of 5.3 dl / g
g and 0.030 g of polymer (5o) were dissolved by stirring 10 ml of methanesulfonic acid (hereinafter abbreviated as MSA) at room temperature. After filtering the solution through a 1G2 glass filter,
It was cast on a glass plate in a nitrogen atmosphere to a thickness of 600 μm. After being left as it was for 1 hour in a nitrogen atmosphere, it was immersed in ion-exchanged water to be solidified. The obtained membrane was immersed in ion-exchanged water for several days while exchanging the ion-exchanged water until no acid was detected. After that, the film was fixed on a metal frame and dried under a nitrogen stream. The evaluation results are shown in Table 1.
FIG. 1 shows the transmission IR spectrum of the film, which was measured using a Hitachi Ltd. model 270-30 infrared spectrophotometer.

(Examples 19 to 28) Membranes were prepared by the same procedure as in Example 17 except that the mixing ratio with the polymer was changed. The evaluation results are shown in Table 1.

(Example 23) Carbon black having a platinum loading of 20 wt% (particle size 20 to 30 nm)
72 g and Nafion (registered trademark) solution (manufactured by DuPont;
The paste was prepared by uniformly dispersing 1 g of “Nafion (registered trademark) solution 20%”) in 5 g of glycerin. The obtained paste was applied by spraying on one surface of the polymer electrolyte membrane obtained in Example 1 and dried under reduced pressure. Similarly, the paste was applied to the other surface and dried under reduced pressure. Obtained /
The amount of platinum supported on the electrode assembly was 0.5 mg / cm 2. When this conductivity was measured, it was 1.5 × 10 ⁻³ S / c.
It was m.

(Comparative Examples 1 and 2) Instead of the basic polymer having an acidic group, the following structures;

[Chemical 18] Polybenzimidazole (hereinafter abbreviated as PBI) was used, and N, N-dimethylacetamide (hereinafter abbreviated as DMAc) was used as the solvent, to prepare a film in the same manner as in the example. The evaluation results are shown in Table 1.

(Comparative Example 3) Instead of the basic polymer having an acidic group, the following structure:

[Chemical 19] Polybenzimidazole (hereinafter abbreviated as p-PBI)
A film was prepared in the same manner as in Example except that was used. The evaluation results are shown in Table 1.

Comparative Example 4 N which is a commercially available ion exchange membrane
Various evaluations were performed on afion (registered trademark) 112 (manufactured by DuPont). The evaluation results are shown in Table 1.

[0049]

[Table 1]

[0050]

EFFECTS OF THE INVENTION The polymer electrolyte of the present invention can provide a polymer electrolyte, a polymer electrolyte membrane, and a membrane / electrode assembly having excellent ionic conductivity and durability.

[Brief description of drawings]

FIG. 1 is an IR spectrum of the film obtained in Example 17.

[Procedure amendment]

[Submission date] June 19, 2002 (2002.6.1)
9)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

(Examples 18 to 28) A film was prepared in the same procedure as in Example 17, except that the mixing ratio with the polymer was changed. The evaluation results are shown in Table 1.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction content]

[0045] (Example 2 9) a carbon black supported platinum amount is 20 wt% (particle diameter of 20 to 30 nm) 0.
72 g and Nafion (registered trademark) solution (manufactured by DuPont;
The paste was prepared by uniformly dispersing 1 g of “Nafion (registered trademark) solution 20%”) in 5 g of glycerin. The obtained paste was applied by spraying on one surface of the polymer electrolyte membrane obtained in Example 1 and dried under reduced pressure. Similarly, the paste was applied to the other surface and dried under reduced pressure. Obtained /
The amount of platinum supported on the electrode assembly was 0.5 mg / cm 2. When this conductivity was measured, it was 1.5 × 10 ⁻³ S / c.
It was m.

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Claims (5)

[Claims] 1. A polybenzoxazole or polybenzthiazole having at least one group selected from the group consisting of (a) a sulfonic acid group and a salt thereof, or a phosphonic acid group and a salt of Su, in a molecule, (B) One or more groups selected from the group consisting of sulfonic acid groups and salts thereof, phosphonic acid groups and salts thereof, carboxylic acid groups and salts thereof in one molecule
A blended polymer electrolyte comprising a mixture with one or more basic polymers. 2. Polybenzoxazole or polybenzthiazole is represented by the following general formula (1) or (5); [Formula (1) represents that the repeating unit consisting of Ar ¹ and Ar ² and the repeating unit consisting of Ar ³ and Ar ⁴ are linked randomly or in a block. In the formula, Ar
¹ and Ar ³ are represented by the following general formula (2); Represents one or more residues selected from the residues represented by
r ¹ and Ar ³ may be the same or different. X ¹
And X ² represents O or S. Y is O, S, C = O, CH
Represents any one of 2, C (CH ₃ ) ₂ , C (CF ₃ ), and S (═O) ₂ . Ar ² is represented by the following general formula (3); Represents one or more residues selected from the group represented by. Ar
⁴ is the following general formula (4); Represents one or more residues selected from the group consisting of residues represented by. n ¹ is an integer of ¹ to 10000, m ¹ is 0 to 10
Represents an integer of 000. ] [Chemical 5] [Formula (5) represents that each repeating unit is connected at random or in a block. In the formula, X ³ and X ⁴ represent either an S atom or an O atom, and these may be the same or different. Z is a SO ₃ H group,
It represents one or more groups selected from PO ₃ H ₂ groups and salts thereof. q represents an integer of 1 to 3, n ² represents an integer of 1 to 10000, and m ² represents an integer of 0 to 10000. ] The blend polymer electrolyte of Claim 1 represented by these. 3. The basic polymer is one or more selected from the group consisting of a polymer of 2-vinylpyridine and its copolymer, 4-vinylpyridine and its copolymer, polybenzimidazole, polyquinoline, polyquinoxaline. The blended polymer electrolyte according to claim 1, wherein the blended polymer electrolyte is a compound according to claim 1. 4. An electrolyte membrane containing the blended polymer electrolyte according to claim 1 as a main component. 5. A membrane / electrode assembly comprising the blend polymer electrolyte membrane according to claim 1 in a membrane and / or an electrode layer.