JP5080019B2 - Solid polymer electrolyte - Google Patents

Description

  The present invention relates to a solid polymer electrolyte composed of a rigid heterocyclic polymer and a polymer having proton conductivity, and a fuel cell.

  A solid polymer electrolyte is a solid polymer material having an electrolyte group in a polymer chain, and has a property of selectively permeating a cation or an anion by firmly binding to a specific ion. It is formed into particles, fibers, or membranes, and is used for various applications such as electrodialysis, diffusion dialysis, and battery membranes.

  A fuel cell is provided with a pair of electrodes on both sides of a proton-conducting solid polymer electrolyte membrane, supplies hydrogen gas, methanol, or the like as a fuel to one electrode (fuel electrode), and oxygen gas or air as an oxidant. It supplies to an electrode (air electrode) and obtains an electromotive force. In water electrolysis, hydrogen and oxygen are produced by electrolyzing water using a solid polymer electrolyte membrane.

  Perfluorosulfonic acid membrane with high proton conductivity known by the trade names Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.) Fluorine-based electrolyte membranes represented by them are widely used as solid polymer electrolyte membranes for fuel cells and water electrolysis because of their excellent chemical stability.

  Moreover, salt electrolysis produces sodium hydroxide, chlorine, and hydrogen by electrolyzing a sodium chloride aqueous solution using a solid polymer electrolyte membrane. In this case, since the solid polymer electrolyte membrane is exposed to chlorine, high temperature, and high concentration sodium hydroxide aqueous solution, it is not possible to use a hydrocarbon electrolyte membrane having poor resistance to these. For this reason, solid polymer electrolyte membranes for salt electrolysis are generally resistant to chlorine and high-temperature, high-concentration sodium hydroxide aqueous solution, and in addition, partly on the surface to prevent back diffusion of generated ions. A perfluorosulfonic acid film into which a carboxylic acid group is introduced is used.

  By the way, a fluorine-based electrolyte typified by a perfluorosulfonic acid membrane has a very large chemical stability because it has a C—F bond, and is used for the fuel cell, water electrolysis, or salt electrolysis described above. In addition to these solid polymer electrolyte membranes, they are also used as solid polymer electrolyte membranes for hydrohalic acid electrolysis, and also widely applied to humidity sensors, gas sensors, oxygen concentrators, etc. using proton conductivity Has been.

  However, the fluorine-based electrolyte has a drawback that it is difficult to manufacture and is very expensive. Therefore, fluorine-based electrolyte membranes are used in limited applications such as space or military polymer electrolyte fuel cells, and are used in consumer applications such as polymer electrolyte fuel cells as low-pollution power sources for automobiles. Application was difficult.

  Therefore, an electrolyte membrane obtained by sulfonating an aromatic hydrocarbon polymer represented by engineering plastics has been proposed as an inexpensive solid polymer electrolyte membrane. (For example, see Patent Documents 1, 2, 3, 4, and 5). An aromatic hydrocarbon electrolyte membrane obtained by sulfonating these engineering plastics has an advantage of easy production and low cost when compared with a fluorine electrolyte membrane represented by Nafion. However, it has a drawback that it is very weak in terms of oxidation resistance.

  According to Non-Patent Document 1, it is reported that, for example, sulfonated polyether ether ketone and polyether sulfone deteriorate from an ether portion adjacent to sulfonic acid. From this, it is considered that when an electron donating group is present in the vicinity of the sulfonic acid, the oxidative degradation starts therefrom. Therefore, for the purpose of improving oxidation resistance, a sulfonated polyphenylenesulfone whose main chain is composed of only an electron-withdrawing group and an aromatic ring has been proposed (Patent Document 6), and sulfonated by introducing a sulfonic acid into a site adjacent to the sulfonate group. Polysulfone has been proposed (Non-Patent Document 2).

  However, according to Patent Document 7, the aromatic hydrocarbon electrolyte membrane is deteriorated not only by oxidative deterioration but also by a sulfonic acid group, which is a proton-conductive substituent directly bonded to the aromatic ring, under strong acid and high temperature. It is considered that the ionic conductivity is decreased due to desorption, and sulfonated polyphenylenesulfone and sulfonated polysulfone as described in Patent Document 6 and Non-Patent Document 2 cannot avoid deterioration due to sulfonic acid desorption. Therefore, it is not desirable that the proton conductive substituent is a sulfonic acid, and Patent Document 7 proposes to use an alkylsulfonic acid instead of the sulfonic acid. This is effective in improving the decrease in ionic conductivity due to elimination of sulfonic acid, but the main chain of the aromatic polymer used contains an electron-donating group, which is inferior in oxidation resistance.

On the other hand, azole polymers are expected as solid electrolyte membranes for fuel cells as polymers having excellent heat resistance and chemical resistance.
For example, a sulfonated azole polymer has been reported as an azole polymer having proton conductivity (Patent Document 8). However, as described above, a sulfonic acid group introduced onto an aromatic ring using a polymer as a raw material is likely to undergo a desulfonic acid reaction due to acid or heat, and is sufficiently durable to be used as an electrolyte membrane for a fuel cell. I can not say.

Non-patent document 3, for example, reports an azole polymer having a hydroxyl group and a method for producing the azole polymer. There is also a report example of conductivity measurement of an ion implantation product of an azole polymer film having a hydroxyl group (Non-Patent Document 4).
However, none of these has been focused on as a functional group for ion-conducting a hydroxyl group, and none of them has sufficiently exemplified durability under the conditions for use with a fuel cell.
Further, Patent Document 9 is an example in which a polybenzazole-based polymer is cited as a reinforcing material for a solid polymer electrolyte membrane, that is, a support membrane for an ion exchange membrane.

JP-A-6-93114 JP-A-9-245818 Japanese Patent Laid-Open No. 11-116679 Japanese National Patent Publication No. 11-510198 Japanese National Patent Publication No. 11-515040 JP 2000-80166 A JP 2002-110174 A JP 2002-146018 A JP 2005-68396 A Polymer Papers Vol. 59, no. 8, 460-473 pages Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 34, 241-2438 (1996) Polymer, 35, (1994) 3091

  An object of the present invention is to provide a solid polymer electrolyte excellent in ion conductivity and oxidation resistance.

で表わされる繰り返し単位よりなる群から選ばれる少なくとも１種の繰り返し単位からなり、０．５ｇ／１００ｍｌの濃度のメタンスルホン酸溶液で２５℃にて測定した還元粘度が０．０５〜２００ｄｌ／ｇである剛直系複素環高分子からなる層とプロトン導電性を有する高分子からなる層との積層体からなる固体高分子電解質であって、剛直系複素環高分子からなる層について、下記式（I）、（II）

（φは配向軸に対してＸ線回折面がなす角で、Ｆは回折強度である。）
で算出される面内方向の配向度（ｆ）が０〜０．３であり、厚み方向の配向度（ｆ）が０．５〜１である固体高分子電解質である。本発明によりイオン伝導性および耐酸化性に優れた固体高分子電解質が提供できる。 The present invention is a solid polymer electrolyte comprising a rigid heterocyclic polymer having a hydroxyl group and a polymer having proton conductivity. Specifically, the following formulas (A) and (B)

The reduced viscosity measured at 25 ° C. with a methanesulfonic acid solution having a concentration of 0.5 g / 100 ml is at least 0.05 to 200 dl / g, comprising at least one repeating unit selected from the group consisting of repeating units represented by A solid polymer electrolyte composed of a laminate of a layer composed of a certain rigid heterocyclic polymer and a layer composed of a proton-conducting polymer , wherein the layer composed of a rigid heterocyclic polymer is represented by the following formula (I ), (II)

(Φ is the angle formed by the X-ray diffraction surface with respect to the orientation axis, and F is the diffraction intensity.)
Is a solid polymer electrolyte having an in-plane orientation degree (f) of 0 to 0.3 and a thickness direction orientation degree (f) of 0.5 to 1 . According to the present invention, a solid polymer electrolyte excellent in ion conductivity and oxidation resistance can be provided.

  Low cost, high durability solid excellent in oxidation resistance and the like suitable for electrolyte membranes used in fuel cells, water electrolysis, hydrohalic acid electrolysis, salt electrolysis, oxygen concentrators, humidity sensors, gas sensors, etc. A polymer electrolyte can be obtained. A fuel cell using the polymer electrolyte can be obtained.

  The present invention is a solid polymer electrolyte excellent in ion conductivity and oxidation resistance. More preferably, the solid polymer electrolyte is in the form of a film having a thickness of 10 to 200 μm. More preferred is a solid polymer electrolyte comprising a laminate of a layer made of a rigid heterocyclic polymer and a layer made of a polymer having proton conductivity.

で表わされる繰り返し単位よりなる群から選ばれる少なくとも１種の繰り返し単位からなり、０．５ｇ／１００ｍｌの濃度のメタンスルホン酸溶液で２５℃にて測定した還元粘度が０．０５〜２００ｄｌ／ｇである剛直系複素環高分子からなる固体高分子電解質である。 <Rigid heterocyclic polymers>
The rigid heterocyclic polymer in the present invention has the following formulas (A) and (B):

The reduced viscosity measured at 25 ° C. with a methanesulfonic acid solution having a concentration of 0.5 g / 100 ml is at least 0.05 to 200 dl / g, comprising at least one repeating unit selected from the group consisting of repeating units represented by It is a solid polymer electrolyte composed of a certain rigid heterocyclic polymer.

<Method for producing rigid heterocyclic polymer>
The rigid heterocyclic polymers as described above can be industrially produced with good productivity by a conventionally known technique as reported in Polymer, 39, (1998) 5981.

で表わされる芳香族アミンおよびその強酸塩及び又は水和物よりなる群より選ばれる少なくとも１種と、下記式（Ｄ）

（ＬはＯＨ、ハロゲン原子、またはＯＲで表される基であり、Ｒは炭素数６〜２０の芳香族基である）
で表わされる芳香族ジカルボン酸類よりなる群から選ばれる少なくとも１種とを反応させる方法が好ましく挙げられる。 That is, the following formula (C)

And at least one selected from the group consisting of aromatic amines and strong acid salts and / or hydrates thereof, and the following formula (D)

(L is a group represented by OH, a halogen atom, or OR, and R is an aromatic group having 6 to 20 carbon atoms)
The method of making it react with at least 1 sort (s) chosen from the group which consists of aromatic dicarboxylic acid represented by these is preferable.

Here, preferred examples of the strong acid include hydrochloric acid, phosphoric acid and sulfuric acid.
One or more of the hydrogen atoms in the aromatic group of R are each independently a halogen group such as fluorine, chlorine or bromine; an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group or a hexyl group; It may be substituted with a C5-C10 cycloalkyl group such as a cyclopentyl group or a cyclohexyl group; an alkoxycarbonyl group such as a methoxycarbonyl group or an ethoxycarbonyl group.

The number of moles of each monomer (reaction component) is the above formula (1)
The following mathematical formula (1)
0.8 ≦ (c) / (d) ≦ 1.2 (1)
(Wherein c is the aromatic amine derivative represented by the above formula (C), and d is the number of moles charged for the aromatic dicarboxylic acid derivative represented by the above formula (D))
Are preferably satisfied simultaneously. When (c) / (d) is smaller than 0.8 or larger than 1.2, it may be difficult to obtain a polymer having a sufficient degree of polymerization. The lower limit of (c) / (d) is suitably 0.9 or more, more preferably 0.93 or more, and even more preferably 0.95 or more. Moreover, as an upper limit of (c) / (d), 1.1 or less is suitable, More preferably, it is 1.07 or less, More preferably, it is 1.05 or less. Therefore, it can be said that the optimum range of (c) / (d) in the present invention is 0.95 ≦ (c) / (d) ≦ 1.05.

  For the reaction, either a reaction performed in a solvent or a solvent-free heating and melting reaction can be employed. For example, it is preferable to carry out a heating reaction in a reaction solvent described later with stirring. The reaction temperature is preferably 50 ° C to 500 ° C, more preferably 100 ° C to 350 ° C. This is because if the temperature is lower than 50 ° C., the reaction does not proceed, or if the temperature is higher than 500 ° C., side reactions such as decomposition tend to occur. Although the reaction time depends on temperature conditions, it is usually 1 hour to several tens of hours. The reaction can be carried out from under pressure to under reduced pressure.

  The reaction usually proceeds even without a catalyst, but a transesterification catalyst may be used if necessary. Examples of transesterification catalysts used in the present invention include antimony compounds such as antimony trioxide, stannous acetate, tin chloride, tin octylate, tin compounds such as dibutyltin oxide and dibutyltin diacetate, and alkaline earth metal salts such as calcium acetate. And phosphorous acid such as alkali metal salts such as sodium carbonate and potassium carbonate, diphenyl phosphite and triphenyl phosphite.

In the reaction, a solvent can be used as necessary. Preferred solvents include 1-methyl-2-pyrrolidone, 1-cyclohexyl-2-pyrrolidone, dimethylacetamide, dimethyl sulfoxide, diphenyl ether, diphenyl sulfone, dichloromethane, chloroform, tetrahydrofuran, o-cresol, m-cresol, p-cresol, Although phosphoric acid, polyphosphoric acid, etc. can be mentioned, it is not limited to this.
In order to prevent decomposition and coloring of the rigid heterocyclic polymer, the reaction is desirably performed in a dry inert gas atmosphere.

  The reduced viscosity of the rigid heterocyclic polymer thus produced has a value measured in a methanesulfonic acid solution having a concentration of 0.5 g / 100 ml at 25 ° C. in the range of 0.05 to 200 dl / g. It is. The preferable range of the reduced viscosity of the rigid heterocyclic polymer is 1.0 to 100 dl / g, more preferably 10 to 80 dl / g or less.

<Polymer having proton conductivity>
The polymer having proton conductivity used in the present invention is, for example, a monomer homopolymer, block copolymer, random copolymer, or —SO ₃ having an ion exchange group such as —SO ₃ H. Examples thereof include perfluorocarbon sulfonic acid resins and polyether ether ketone sulfonic acid resins having proton conductivity such as those obtained by introducing an ion exchange group such as H group after post-treatment. In particular, the polymer having proton conductivity is preferably a perfluorocarbon sulfonic acid resin.

<Electrolyte membrane>
The solid polymer electrolyte of the present invention preferably has a film shape with a thickness of 10 to 200 μm. The thickness of the electrolyte membrane is more preferably 30 to 100 μm. A thickness of more than 10 μm is preferable to obtain a membrane strength that can withstand practical use, and a thickness of less than 200 μm is preferable in order to reduce membrane resistance, that is, improve power generation performance. The thickness can be controlled by the solution concentration or the coating thickness on the substrate in the case of the solution casting method, and can be controlled by the solution concentration or the pressure of the press in the case of the pressing method.

<Composite and laminate>
The solid polymer electrolyte of the present invention comprises a rigid heterocyclic polymer and a polymer having proton conductivity. Even a solid polymer electrolyte comprising a composition of a rigid heterocyclic polymer and a polymer having proton conductivity, a layer comprising a rigid heterocyclic polymer and a layer comprising a proton conducting polymer The laminated body may be sufficient. In the case of the composition, it is preferably 1 to 800 parts by weight, preferably 3 to 300 parts by weight, and more preferably 5 to 100 parts by weight of the polymer having proton conductivity with respect to 100 parts by weight of the rigid heterocyclic polymer. In the case of a laminate, a layer made of a polymer having proton conductivity may be provided on one side or both sides of a layer made of a rigid heterocyclic polymer. Examples of the lamination method include, but are not limited to, a known press method, hot press method, cast method, spin coating method, and laminate method.

（φは配向軸に対してX線回折面がなす角で、Ｆは回折強度である。）
で算出される面内方向の配向度（ｆ）が、好ましくは０〜０．３、より好ましくは０〜０．１である。また上記式（Ｉ）、(II)で同様に算出される厚み方向の配向度（ｆ）が好ましくは０．５〜１、より好ましくは０．６〜１．０である。 <Rigid heterocyclic polymer layer>
When the electrolyte is a laminate, the layer made of a rigid heterocyclic polymer has the following formulas (I) and (II):

(Φ is the angle formed by the X-ray diffraction surface with respect to the orientation axis, and F is the diffraction intensity.)
The degree of orientation (f) in the in-plane direction calculated by is preferably 0 to 0.3, more preferably 0 to 0.1. Further, the degree of orientation (f) in the thickness direction calculated in the same manner by the above formulas (I) and (II) is preferably 0.5 to 1, more preferably 0.6 to 1.0.

  In the above formulas (I) and (II), the degree of orientation (f) can be determined by wide-angle X-ray diffraction (WAX) measurement. WAX measurement is performed under conditions where the incident X-ray is perpendicular to the MD (cast direction) axis and perpendicular to the film surface (Thru view), and the incident X-ray is perpendicular to the MD axis and parallel to the film surface (Edge view). ) And Hermans' handling is adopted for the estimation of the orientation degree f.

  The orientation degree f in the in-plane direction can be obtained by calculating the root mean square of the direction cosine with respect to the MD for the (110) diffraction surface in the Thru view according to the formula (I), and calculating the orientation degree f (formula (II)). . Also, the orientation degree f in the thickness direction is obtained by calculating the root mean square of the direction cosine with respect to the normal direction of the film surface with respect to the (200) diffraction plane in the edge view according to the formula (I). Can be calculated.

<Method for producing membrane>
In order to form a layer composed of a rigid heterocyclic polymer, it is preferable to carry out (i) a casting method or (ii) a pressing method.

(Cast method)
The casting method is a method of forming a film by casting a polymer solution (dope) containing a rigid heterocyclic polymer and a solvent on a substrate such as a glass plate and removing the solvent.
The solvent is not particularly limited as long as it dissolves the rigid heterocyclic polymer and can be removed thereafter. N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, N-methyl-2- Aprotic polar solvents such as pyrrolidone and hexamethylphosphonamide, and strong acids such as polyphosphoric acid, methanesulfonic acid, sulfuric acid, and trifluoroacetic acid can be used.

  A plurality of these solvents may be used as a mixture within a possible range. 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 concentration of the rigid heterocyclic polymer in the dope is preferably 0.1 to 8% by weight. If it is too low, the moldability will deteriorate, and if it is too high, the workability will deteriorate. In the solution casting method, by setting the concentration of the rigid heterocyclic polymer in the dope within a predetermined range, a film having a low degree of orientation in the in-plane direction can be obtained.

  As a casting method, it is preferable to employ a method in which a dope is cast on a support using a doctor blade, a bar coater, an applicator, etc., the solvent is washed, and then the film is dried. As drying temperature, 0 degreeC-200 degreeC, Preferably 20 degreeC-150 degreeC, Furthermore, 50 degreeC-80 degreeC can be utilized.

(Pressing method)
Rigid heterocyclic polymers have high crystallinity, and ordinary extrusion film formation cannot provide an isotropic film in the in-plane direction. Therefore, an isotropic film can be obtained in the in-plane direction by sandwiching a dope containing a rigid heterocyclic polymer and a solvent between the substrates and applying pressure. The solvent is the same as in the casting method. The concentration of the rigid heterocyclic polymer in the dope is preferably 0.1 to 30% by weight, more preferably 0.5 to 8% by weight. The pressure is preferably 0.01 to 1000 MPa, more preferably 1 to 10 MPa. It is preferable to heat at the time of film formation. The heating temperature is preferably 100 to 300 ° C, preferably 130 to 250 ° C.

<Pellets>
In addition to the above-mentioned film shape, the solid polymer electrolyte may have a pellet-like shape. Examples of the manufacturing method in the case of pellets include a compression roll method, a briquetting method, and a tableting method. More specifically, it is preferable to perform granulation using a tablet molding machine or a compression molding machine.

<Membrane / electrode assembly>
The membrane / electrode assembly of the present invention has catalyst electrodes on both surfaces of the electrolyte membrane of the present invention. The catalyst electrode is one in which fine particles of catalyst metal are supported on a conductive material. The catalyst metal may be any metal as long as it promotes a hydrogen oxidation reaction and an oxygen reduction reaction. For example, platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium, tungsten, manganese, vanadium, or an alloy thereof can be given. In particular, platinum is often used. The particle size of the catalytic metal is usually 10 to 300 angstroms.

The conductive material may be an electron conductive material. Examples of the conductive material include various metals and carbon materials. Examples of the carbon material include carbon black such as furnace black, channel black, and acetylene black, activated carbon, and graphite. These may be used alone or in combination. The amount of catalyst metal supported is preferably 0.01 to 10 mg / cm ² in a state where the electrode is molded.

  As a method of supporting the catalyst metal on these conductive materials, there are a method of depositing the catalyst metal on the surface of the conductive material by a reduction method, a method of suspending the catalyst metal in a solvent, and applying this to the surface of the conductive material. .

(Fuel cell)
The solid polymer electrolyte of the present invention is preferably used for a fuel cell. In the fuel cell of the present invention, a single cell is formed by arranging a current collector with a groove forming a fuel channel or an oxidant channel called a separator on the outside of the membrane / electrode assembly. It is configured by laminating a plurality via a cooling plate or the like.

  A fuel cell has a single cell in which a grooved current collector that forms a fuel flow path or an oxidant flow path called a separator is disposed on the outside of a membrane / electrode assembly, and a plurality of such single cells, It is configured by stacking via a cooling plate or the like. It is desirable to operate the fuel cell at a high temperature because the catalytic activity of the electrode increases and the electrode overvoltage decreases. However, since the electrolyte membrane does not function without moisture, it needs to be operated at a temperature at which moisture management is possible. The preferable range of the operating temperature of the fuel cell is from room temperature to 100 ° C.

The membrane / electrode assembly has catalyst electrodes on both sides of the electrolyte membrane. The catalyst electrode can be prepared by supporting catalyst metal fine particles on a conductive material. The catalyst metal used for the catalyst electrode may be any metal that promotes the oxidation reaction of hydrogen and the reduction reaction of oxygen. For example, platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron , Cobalt, nickel, chromium, tungsten, manganese, vanadium, or alloys thereof. In particular, platinum is often used. The particle size of the metal serving as a catalyst is usually 10 to 300 angstroms. When these catalysts are attached to a carrier such as carbon, the amount of the catalyst used is small and advantageous in terms of cost. The amount of the catalyst supported is preferably 0.01 to 10 mg / cm ² with the electrode formed.

  As the conductive material, any material can be used as long as it is an electron conductive material, and examples thereof include various metals and carbon materials. Examples of the carbon material include carbon black such as furnace black, channel black, and acetylene black, activated carbon, graphite, and the like, and these are used alone or in combination.

  As a method for supporting the catalyst metal on these conductive materials, the catalyst metal is deposited on the surface of the conductive material (mainly used in the case of carbon materials) by a reduction method, or the catalyst metal is suspended in a solvent. There is a method of applying to the surface of a conductive material.

  In the membrane / electrode assembly, a solution obtained by dissolving a PPSO polymer into which a sulfonic acid sandwiching a spacer structure or a sulfonamidated sulfonic acid sandwiching a spacer structure is dissolved in a solvent used for forming an electrolyte membrane is used as a catalyst electrode layer. It is created by applying and bonding to the electrolyte membrane.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited at all by these. In addition, each measured value in the following examples is a value obtained by the following method.

[Reduced viscosity]
It is a value measured at 25 ° C. with a methanesulfonic acid solution having a concentration of 0.5 g / 100 ml.

[Ion conductivity measurement]
(Film, laminate)
The sample membrane was subjected to a four-terminal impedance measurement in an area of a frequency of 0.1 Hz to 65 kHz using an electrochemical impedance measuring device (manufactured by Solartron, SI1287), and ion conductivity was measured. The measurement was performed by holding a 1.5 cm × 3 cm strip sample at 75 ° C. in an atmosphere of 90% humidity.
(pellet)
Both sides of the obtained pellet were sandwiched between electrodes, and an electrochemical impedance measuring device (manufactured by Solartron, SI1287) was used to hold at 75 ° C. in an atmosphere of 90% humidity in a frequency range of 0.1 Hz to 65 kHz.

[Oxidation resistance test]
A 0.5 mg sample film was immersed in a Fenton reagent (containing 40 ppm of iron) heated to 60 ° C., and the time required for the sample to dissolve in the Fenton reagent was determined. The Fenton reagent was prepared by adding 1.9 mg of iron sulfate heptahydrate to 20 g of 30 wt% aqueous hydrogen peroxide.

（φは配向軸に対してX線回折面がなす角で、Ｆは回折強度である。） [Orientation]
For wide-angle X-ray diffraction (WAX) measurement, CuKα monochromatized with Confocal Mirror from ROTA FLEX RU200B manufactured by Rigaku Denki was used, and diffraction X-rays by transmission method were recorded on an imaging plate with a camera length of 95 mm. As a WAX measurement sample, the film is cut into strips of length (// MD) 6.5 mm × width 2 mm so that the MD (cast direction) axes are aligned, and a laminated sample having a thickness of 1.5 mm is formed by laminating them. Prepared. In the WAX measurement, the laminated sample is arranged under the conditions that the incident X-ray is perpendicular to the MD axis and perpendicular to the film surface (Thru view), and the incident X-ray is perpendicular to the MD axis and parallel to the film surface. This was carried out under various conditions (Edge view), and Hermans' handling was adopted for estimating the orientation degree f. The orientation degree f in the in-plane direction was obtained by calculating the root mean square of the direction cosine with respect to the MD for the (110) diffraction plane in Thru view according to the formula (I), and calculating the orientation degree f (formula (II)). Also, the orientation degree f in the thickness direction is obtained by calculating the root mean square of the direction cosine with respect to the normal direction of the film surface with respect to the (200) diffraction plane in the edge view according to the formula (I). Calculated.

(Φ is the angle formed by the X-ray diffraction surface with respect to the orientation axis, and F is the diffraction intensity.)

[Fuel cell single cell performance evaluation]
The membrane / electrode assembly was incorporated into an evaluation cell, and the fuel cell output performance was evaluated. Hydrogen / oxygen was used as a reaction gas, and both were humidified through a water bubbler at 70 ° C. at a pressure of 1 atm, and then supplied to the evaluation cell. The gas flow rate was 60 ml / min for hydrogen, 40 ml / min for oxygen, and the cell temperature was 75 ° C. The battery output performance was evaluated by an H201B charge / discharge device (made by Hokuto Denko).

[Reference Example 1] (Monomer Synthesis 1)
17.772 parts by weight of 2,3,5,6-tetraaminopyridine trihydrochloride monohydrate was dissolved in 100 parts by weight of water deaerated with nitrogen. 13.208 parts by weight of 2,5-dihydroxyterephthalic acid was dissolved in 137 parts by weight of 1M aqueous sodium hydroxide solution and degassed with nitrogen. 2,3,5,6-tetraaminopyridine trihydrochloride monohydrate solution was dropped into 2,5-dihydroxyterephthalic acid disodium salt aqueous solution over 10 minutes, and 24.3 parts by weight of polyphosphoric acid and The salt obtained by adding water degassed with 35 parts by weight of nitrogen and adding 1 part by weight of acetic acid was filtered, dispersed and mixed in 3000 parts by weight of water degassed with nitrogen, and filtered again. This dispersion mixing and filtration operation was repeated three times to obtain 2,3,5,6-tetraaminopyridine / 2,5-dihydroxyterephthalate.

[Reference Example 2] (Polymer polymerization)
22.88 parts by weight of 2,3,5,6-tetraaminopyridine / 2,5-dihydroxyterephthalate obtained in Reference Example 1, 62.54 parts by weight of polyphosphoric acid, 14.76 parts by weight of phosphorus pentoxide The mixture was added and stirred at 100 ° C. for 1 hour. Thereafter, the temperature was raised to 140 ° C. over 2 hours and stirred at 140 ° C. for 1 hour. Thereafter, the temperature was raised to 180 ° C. over 1 hour, and the reaction was carried out at 180 ° C. for 5 hours to obtain a polymer dope. As a result of measurement with a polarizing microscope, this polymer dope exhibited liquid crystallinity. The dope was reprecipitated with water and washed to obtain a polymer. The polymer obtained had a reduced viscosity of 15 dl / g.

[Example 1] (Creation of cast film)
1 part by weight of the polymer obtained by reprecipitation in Reference Example 2 was dissolved in 100 parts by weight of methanesulfonic acid to obtain a polymer dope. The obtained polymer dope was cast with a doctor knife to obtain a cast film having a film thickness of 15 μm. The film was sandwiched on both sides by a Du Pont Nafion film having a film thickness of 170 μm, and the ionic conductivity and oxidation resistance were measured.

[Example 2] (Preparation of pellets)
The polymer of Reference Example 2 was molded into pellets by applying a pressure of 500 kgf / cm ² for 1 minute with an IR tablet machine. The pellets were immersed in Nadion perfluorinated solution manufactured by Aldrich for 1 minute and dried at 120 ° C. for 8 hours to obtain a film. The ionic conductivity and oxidation resistance of this pellet were measured.

[Example 3] (Production of catalyst electrode layer, membrane / electrode assembly, fuel cell)
The methanesulfonic acid solution used in Example 1 described above was added to 40% by weight of platinum-supported carbon so that the weight ratio of platinum-supported carbon and polymer electrolyte was 2: 1 and dispersed uniformly. A paste (electrocatalyst coating solution) was prepared. This electrode catalyst coating solution was applied to both sides of the electrolyte membrane obtained in Example 1, then washed with water and dried to prepare a membrane / electrode assembly having a platinum loading of 0.25 mg / cm ² . When this was used to evaluate the performance of a single fuel cell, an output of 40 mW was shown.

  The electrolyte membrane of the present invention can be used in fuel cells, water electrolysis, hydrohalic acid electrolysis, salt electrolysis, oxygen concentrators, humidity sensors, gas sensors, and the like.

Claims (6)

The following formulas (A) and (B)

The reduced viscosity measured at 25 ° C. with a methanesulfonic acid solution having a concentration of 0.5 g / 100 ml is at least 0.05 to 200 dl / g, comprising at least one repeating unit selected from the group consisting of repeating units represented by A solid polymer electrolyte composed of a laminate of a layer composed of a certain rigid heterocyclic polymer and a layer composed of a proton-conducting polymer , wherein the layer composed of a rigid heterocyclic polymer is represented by the following formula (I ), (II)

(Φ is the angle formed by the X-ray diffraction surface with respect to the orientation axis, and F is the diffraction intensity.)
A solid polymer electrolyte having an in-plane orientation degree (f) of 0 to 0.3 and a thickness direction orientation degree (f) of 0.5 to 1 calculated in (1).   The solid polymer electrolyte according to claim 1, which has a film shape with a thickness of 10 to 200 μm.   The solid polymer electrolyte according to claim 1 or 2, wherein the polymer having proton conductivity is a perfluorocarbon sulfonic acid resin. The solid polymer electrolyte according to any one of claims 1 to 3 , which is used for a fuel cell. A membrane / electrode assembly comprising the solid polymer electrolyte according to any one of claims 2 to 4 and a catalyst electrode disposed on both surfaces thereof. A fuel cell comprising the membrane / electrode assembly according to claim 5 .