CN101015081A - Solid polymer electrolyte membrane and method for producing same - Google Patents

Abstract

Disclosed is a solid polymer electrolyte membrane obtained by uniformly mixing a polyazole compound into a perfluorocarbon sulfonic acid resin. Such a solid polymer electrolyte membrane serves as a polymer electrolyte membrane for solid polymer electrolyte fuel cells which has high durability. Also disclosed are a membrane electrode assembly containing such a polymer electrolyte membrane, and a solid polymer electrolyte fuel cell. Specifically disclosed is a solid polymer electrolyte membrane which is produced by a process comprising a polymer electrolyte-containing solution producing step wherein a perfluorocarbon sulfonic acid resin (component A) having an ion exchange capacity of 0.5-3.0 meq/g, a polyazole compound (component B) and an alkali metal hydroxide are dissolved in a protic solvent for obtaining a polymer electrolyte-containing solution wherein the mass ratio between the component A and the component B (A/B) is 2.3-199 and the total mass of the component A and the component B is 0.5-30 wt%, and a film-forming step wherein a film is made from the polymer electrolyte-containing solution.

Description

Solid polymer electrolyte membrane and manufacturing method thereof

technical field

The present invention relates to a fluorine-based solid polymer electrolyte membrane and a method for producing the same, and more particularly to a fluorine-based solid polymer electrolyte membrane suitable for use in solid polymer electrolyte fuel cells and a method for producing the same. In addition, the present invention relates to electrolyte membranes and electrolyte substances for solid polymer electrolyte fuel cells, solutions containing fluorine-based polymer electrolytes suitable for producing separators for electrolysis and dialysis, and methods for producing the same.

Background technique

A fuel cell is a power generation device that obtains electrical energy by electrochemically oxidizing fuels such as hydrogen and methanol, and has recently attracted attention as a clean energy source.

According to the type of electrolyte used, fuel cells are classified into phosphoric acid type, molten carbonate type, solid oxide type, and solid polymer electrolyte type. Among them, solid polymer electrolyte fuel cells have a low standard operating temperature of 100° C. or lower and high energy density, so such solid polymer electrolyte fuel cells are expected to be widely used as power sources for electric vehicles and the like.

The basic structure of a solid polymer electrolyte fuel cell is as follows: it consists of a solid polymer electrolyte membrane and a pair of gas diffusion electrodes bonded to both sides of the solid polymer electrolyte membrane. One electrode supplies oxygen, and an external load circuit is connected between the two electrodes to generate electricity. More specifically, protons and electrons are generated at the hydrogen-side electrode, and the protons move to the oxygen-side electrode through the interior of the solid polymer electrolyte membrane, and react with oxygen to generate water. On the other hand, the electrons flowing out from the hydrogen-side electrode through the wire release electric energy in the external load circuit, and then flow to the oxygen-side electrode through the wire to promote the above-mentioned reaction of generating water.

Regarding the characteristics required of a solid polymer electrolyte membrane, first, high ion conductivity can be cited. It is considered that when protons move inside the solid polymer electrolyte membrane, they are stabilized by hydration of water molecules. Therefore, in addition to ionic conductivity, high water content and high water dispersibility are also important characteristics required for solid polymer electrolyte membranes. In addition, the solid polymer electrolyte membrane is also required to have low gas permeability in order to function as a barrier to prevent the direct reaction of hydrogen and oxygen.

Other properties required for solid polymer electrolyte membranes include: the chemical stability required to allow the electrolyte membrane to withstand the strong oxidizing atmosphere during fuel cell operation, and the mechanical strength required to withstand further thin film formation, etc. .

For the material of the solid polymer electrolyte membrane used in the solid polymer electrolyte fuel cell, because the electrolyte membrane is required to have high chemical stability, fluorine-based ion exchange resins are widely used, among which DuPont Co. The produced main chain is perfluorocarbon, and "NAFION (registered trademark)" has a sulfonic acid group at the end of the side chain. Such fluorine-based ion-exchange resins generally have well-balanced properties required as solid polymer electrolyte materials, but higher durability is increasingly required as such batteries are put into practical use.

Among them, the method being studied is a method of adding a polymer (a polyazole compound) having a nitrogen-containing heterocyclic compound to a perfluorocarbon-based ion exchange resin (see, for example, Korean Patent Application Publication No. 2003-32321 specification , International Publication No. 99/54407 and International Publication No. 98/07164). In addition, Japanese Patent Publication No. 2001-514431 discloses that a perfluorocarbon-based ion exchange resin and a polymer as a porous substrate are dissolved in a common solvent, and the obtained solution is cast to form a membrane. The polymer network structure in which the resin and the porous substrate are interpenetrated. As an example of the porous base material therein, polybenzoxazole and polybenzimidazole which are a kind of polyazole are mentioned.

These nitrogen-containing heterocyclic compounds can improve mechanical stability and thermal stability, and therefore, such compounds are expected to improve the durability of batteries during operation. However, in these studies, an aprotic solvent was used as a solvent for dissolving perfluorocarbon-based ion exchange resins or nitrogen-containing heterocyclic compounds. In addition, Document 3 describes water in addition to the aprotic solvent as a specific example of the solvent used as needed. However, Document 3 does not describe the use of this solvent together with an alkali metal hydroxide. For electrolyte membranes for solid polymer electrolyte fuel cells made using these aprotic solvents, the dispersibility of nitrogen-containing heterocyclic compounds in the electrolyte membrane is generally poor, and nitrogen-containing heterocyclic compounds that can effectively function The amount of the compound is small, and as a result, high durability cannot be obtained. In addition, if the acidic polymer solution is mixed with the basic polymer solution, insoluble large-sized precipitates will usually be formed quickly, making it difficult to obtain a uniform and transparent solution. Thus, a homogeneous film cannot be obtained.

In addition, although nitrogen-containing heterocyclic compounds are dissolved in dipolar aprotic solvents such as dimethylacetamide, high temperatures are usually required for dissolution, so there are many restrictions, for example, the dissolution operation must be performed in a pressure-resistant vessel.

In addition, if the above-mentioned aprotic solvent is used to make a solid polymer electrolyte membrane, when making a solution containing a polymer electrolyte for film formation, or when forming a film from the solution containing a polymer electrolyte, the aprotic The solvent decomposes, and its decomposed products bind to ion-exchange groups, resulting in a decrease in the power generation capacity of the fuel cell. In addition, this decomposed product remains in the exchange membrane, and it takes a long time for a fuel cell assembled with a solid polymer electrolyte membrane with such a residual decomposed product to output power stably at start-up. During this period, the decomposed product and the electrode Catalysts in the fuel cell combine to form catalyst poisons, causing problems such as lower power generation capacity of the fuel cell, and eventually high durability cannot be obtained.

In addition, dimethylsulfoxide (DMSO), dimethylacetamide (DMAC), and dimethylformamide (DMF), which are conventionally used as aprotic solvents, are harmful to the human body and are also harmful to the global environment. Furthermore, since these aprotic solvents have a high boiling point, it takes time to purify them, and high temperature is required to remove these aprotic solvents. Therefore, there are problems such as poor production efficiency of solid polymer electrolyte membranes. In addition, these aprotic solvents are expensive.

Contents of the invention

The object of the present invention is to provide a polymer electrolyte membrane in which polyazole compounds are uniformly mixed in perfluorocarbon sulfonic acid resin. Finally, the present invention provides a highly durable polymer electrolyte membrane for a solid polymer electrolyte fuel cell, a membrane electrode assembly including the electrolyte membrane, and a solid polymer electrolyte fuel cell.

The inventors of the present invention conducted special research to solve the above-mentioned problems, and found that, by dissolving polyazole compounds and perfluorocarbon sulfonic acid resins in a protic solvent together with alkali metal hydroxides, it is possible to obtain A solution of molecular electrolytes. And surprisingly, it was found that by treating the obtained solution containing a polymer electrolyte with a cation exchange resin and/or using a cation exchange membrane to perform dialysis treatment, the alkali metal can be arbitrarily removed, thereby obtaining only polyazole compounds, A solution containing a polymer electrolyte composed of a perfluorocarbon sulfonic acid resin and a protic solvent. The inventor of the present invention further uses this solution that contains polyelectrolyte to carry out film-forming, for the obtained film, especially under the high-temperature low-humidity condition of fuel cell, has carried out battery durability test, finds in the test, this battery in The battery has high durability in terms of hydrogen leakage, pinhole generation, oxidative aging, and the like, and is also excellent in stability of generated voltage at the initial stage of battery operation, thereby completing the present invention.

That is, the present invention provides the following inventions.

(1) A method for manufacturing a solid polymer electrolyte membrane, the method comprising a step of manufacturing a solution containing a polymer electrolyte and a film-forming step of forming a film from the solution containing a polymer electrolyte; In the manufacturing step of the solution, component A, component B and alkali metal hydroxide are dissolved in a protic solvent to produce a solution containing a polymer electrolyte, and the component A has an ion exchange capacity of 0.5meq/g to 3.0meq /g perfluorocarbon sulfonic acid resin, the component B is a polyazole compound, in the manufactured solution containing the polymer electrolyte, the mass ratio (A/B) of the component A to the component B 2.3-199, and the total mass of the component A and the component B is 0.5% by weight to 30% by weight.

(2) The method for producing a solid polymer electrolyte membrane as described in (1) above, wherein the step of producing the solution containing the polymer electrolyte includes adding A process in which the solution obtained by dissolving the perfluorocarbon sulfonic acid resin in the protic solvent is mixed with the solution obtained by dissolving the polyazole compound and the alkali metal hydroxide in the protic solvent.

(3) The method for producing a solid polymer electrolyte membrane as described in (2) above, wherein the step of producing the solution containing the polymer electrolyte includes adding A process in which a solution obtained by dissolving the perfluorocarbon sulfonic acid resin in a protic solvent is added to a solution obtained by dissolving the polyazole compound and the alkali metal hydroxide in a protic solvent.

(4) The method for producing a solid polymer electrolyte membrane according to any one of the above (1) to (3), wherein the alkali metal hydrogen The amount of the oxide is 1 to 100 times equivalent.

(5) The method for producing a solid polymer electrolyte membrane as described in any one of the above (1) to (4), wherein in the step of producing the solution containing the polymer electrolyte, the ion exchange capacity is After 0.5meq/g～3.0meq/g perfluorocarbon sulfonic acid resin, the polyazole compound and the alkali metal hydroxide are dissolved in the protic solvent, the resulting solution is further subjected to cation exchange Resin treatment and/or dialysis treatment using a cation exchange membrane.

(6) The method for producing a solid polymer electrolyte membrane according to any one of (1) to (5) above, wherein, in the film forming step, after forming the film, acid washing is further performed, followed by water washing, And heat treatment as needed.

(7) The method for producing a solid polymer electrolyte membrane according to any one of (1) to (6) above, wherein the perfluorocarbon sulfonic acid resin contains -(CF ₂ -CF ₂ )- A copolymer of repeating units represented by -(CF ₂ -CF(-O-(CF ₂ CFXO) _n -(CF ₂ ) _m -SO ₃ H))-, where X represents F or CF ₃ , n represents an integer of 0 to 5, m represents an integer of 0 to 12, and n and m are not 0 at the same time.

(8) The method for producing a solid polymer electrolyte membrane according to (7) above, wherein -(CF ₂ -CF(-O-(CF ₂ CFXO) _n -(CF ₂ ) _m -SO ₃ H) n in the repeating unit represented by )- is 0, and m is an integer of 1-6.

(9) The method for producing a solid polymer electrolyte membrane as described in any one of the above (1) to (8), wherein the polyazole compound is selected from the group consisting of polyimidazole compounds, polybenzimidazole compounds, At least one compound selected from the group consisting of polybenzobisimidazole compounds, polybenzoxazole compounds, polyoxazole compounds, polythiazole compounds and polybenzothiazole compounds.

(10) The method for producing a solid polymer electrolyte membrane according to (9) above, wherein the polyazole compound is a polybenzimidazole compound.

(11) The method for producing a solid polymer electrolyte membrane according to any one of (1) to (10) above, wherein the protic solvent is mainly water and a protic organic solvent having a boiling point not higher than that of water mixed solvents.

(12) The method for producing a solid polymer electrolyte membrane as described in (11) above, wherein, in the step of producing the solution containing the polymer electrolyte, the obtained solution containing the polymer electrolyte is once distilled off. The protic organic solvent having a boiling point not higher than the boiling point of water is prepared into a solution in which the solvent is a protic solvent mainly composed of water, and then the protic organic solvent is added again.

(13) The method for producing a solid polymer electrolyte membrane according to any one of (1) to (12) above, wherein in the step of producing the polymer electrolyte-containing solution, in the protic solvent A reinforcing material is further added, and the added amount of the reinforcing material is 0.01% by volume to 45% by volume of the total amount of the component A, the component B and the reinforcing material.

(14) The method for producing a solid polymer electrolyte membrane according to (13) above, wherein the reinforcing material is a short fibrous substance having an aspect ratio of 5 or more.

(15) The method for producing a solid polymer electrolyte membrane according to any one of (1) to (14) above, wherein the film forming step includes impregnating the solution containing the polymer electrolyte into the The process of strengthening the porous carrier composed of materials with a porosity of 40% to 99%.

(16) A solid polymer electrolyte membrane obtained by the production method described in any one of (1) to (15) above.

(17) A multilayer solid polymer electrolyte membrane comprising at least one layer of the solid polymer electrolyte membrane described in (16) above.

(18) A membrane electrode assembly comprising the membrane described in (16) or (17) above.

(19) A solid polymer electrolyte fuel cell comprising the membrane electrode assembly described in (18) above.

(20) A solution containing a polymer electrolyte, which is obtained by dissolving component A, component B and alkali metal hydroxide in a protic solvent, and the component A has an ion exchange capacity of 0.5meq/g～ The perfluorocarbon sulfonic acid resin of 3.0meq/g, described component B is polyazole compound, in described solution that contains polyelectrolyte, the mass ratio of described component A and described component B (A/B ) is 2.3-199, and the total mass of the component A and the component B is 0.5% by weight to 30% by weight.

(21) A solution containing a polymer electrolyte, wherein the solution containing a polymer electrolyte described in (20) above is further subjected to cation exchange resin treatment and/or dialysis treatment using a cation exchange membrane to make the solution in the solution A solution containing a polymer electrolyte obtained by reducing or substantially removing alkali metals.

(22) The polymer electrolyte-containing solution as described in (20) or (21) above, wherein the polyazole compound is selected from polyimidazole compounds, polybenzimidazole compounds, polybenzobisimidazole At least one compound in the group consisting of polybenzoxazole compounds, polyoxazole compounds, polythiazole compounds and polybenzothiazole compounds.

The solid polymer electrolyte membrane obtained by the production method of the present invention is particularly excellent in durability under high-temperature and low-humidity conditions of a solid polymer electrolyte fuel cell, and is effective as a polymer electrolyte membrane for a solid polymer electrolyte fuel cell.

Detailed ways

The present invention will be described in detail below.

First, protic solvents that can be used in the present invention will be described. The protic solvent used in the present invention refers to a solvent that easily releases protons after dissociation, such as water, alcohols, carboxylic acids, and fatty acids. Some examples of protic solvents are given below, but they are not limited to these examples as long as they are solvents that easily release protons after dissociation. In addition, in this specification, among protic solvents, protic solvents other than water are referred to as protic organic solvents.

Examples of protic solvents include water; aliphatic alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol , 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isoamyl alcohol, tert-amyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2- Methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2- Octanol, 2-methyl-1-hexanol, 1-nonanol, 3,5,5-trimethyl-1-hexanol, 1-decanol, 1-undecanol, 1-dodecane alcohol, allyl alcohol, propargyl alcohol, benzyl alcohol, cyclohexanol, 1-methyl-cyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, α-terpineol, abietyl alcohol, and fusel oil; solvents with more than 2 functional groups, such as 2-methoxyethanol, 2-ethoxyethanol, 2-(methoxymethoxy)ethanol, 2- Isopropoxyethanol, 2-butoxyethanol, 2-(isoamyloxy)ethanol, 2-(hexyloxy)ethanol, 2-phenoxyethanol, 2-(benzyloxy)ethanol, furfuryl alcohol, Tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, tetraethylene glycol, polyethylene glycol, 1 -Methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, poly Propylene glycol, diacetone alcohol, 2-chloroethanol, 1-chloro-2-propanol, 3-chloro-1,2-propanediol, 1,3-dichloro-2-propanol, 2,2,2-trifluoro Ethanol, 3-hydroxypropionitrile and 2,2'-thiodiethanol; glycols such as 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol , 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-methyl- 2,4-pentanediol, 2-ethyl-1,3-hexanediol, glycerol, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and 1,2,6-hexanetriol Alcohols; phenols such as phenol, cresol, o-cresol, m-cresol, p-cresol and xylenol; fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, trimethylacetic acid , valeric acid, isovaleric acid, hexanoic acid, 2-ethylbutyric acid, octanoic acid, 2-ethylhexanoic acid and oleic acid; inorganic acids such as sulfuric acid, nitric acid and hydrochloric acid. In addition, a small amount of alkylamine or ammonium can also be added to these protic solvents.

As for the perfluorocarbon sulfonic acid resin (ingredient A) that can be used in the present invention, as long as the resin is a so-called perfluorocarbon sulfonic acid resin, there is no particular limitation, however, it is preferred that the perfluorocarbon sulfonic acid resin represented by the following general formula A product obtained by hydrolyzing a perfluorocarbon sulfonic acid resin precursor composed of a copolymer of a fluorinated vinyl ether compound represented by (1) and a fluorinated olefin monomer represented by the following general formula (2).

CF ₂ ＝CF-O-(CF ₂ CFXO) _n -(CF ₂ ) _m -W (1)

In formula (1), X represents an F atom or represents a perfluoroalkyl group having 1 to 3 carbon atoms, n represents an integer of 0 to 5, and m represents an integer of 0 to 12. Also, n and m are not 0 at the same time. W represents a functional group that can be converted into SO ₃ H by hydrolysis.

_CF2 = CFZ (2)

In formula (2), Z represents H, Cl, F or a perfluoroalkyl group having 1 to 3 carbon atoms.

As a functional group that can be converted into SO ₃ H by hydrolysis, SO ₂ F, SO ₂ Cl or SO ₂ Br is preferred. In addition, the perfluorocarbon sulfonic acid resin precursor formed when X in the above general formula is CF ₃ , W is SO ₂ F, and Z is F is preferred, and among them, it is more preferred when n is 0 and m is 0 An integer of ~6 (wherein n and m are not 0 at the same time), X is CF ₃ , W is SO ₂ F, and Z is a perfluorocarbon sulfonic acid resin precursor formed when F, which is therefore, in this In this case, a highly concentrated solution can be obtained.

Such a perfluorocarbon sulfonic acid resin precursor can be synthesized by a known method. For example, known methods include: using a polymerization solvent such as a fluorine-containing hydrocarbon, filling and dissolving the above-mentioned fluoroethylene compound and a fluorinated olefin gas, and making them react to perform polymerization (solution polymerization); without using a solvent such as a fluorine-containing hydrocarbon, The method of polymerizing by using vinyl fluoride compound itself as the polymerization solvent (bulk polymerization); using the aqueous solution of surfactant as the medium, filling the vinyl fluoride compound and fluorinated olefin gas, and making them react to carry out the polymerization method (emulsion polymerization); A method of polymerizing emulsified fluoroethylene compounds and fluorinated olefins by filling them with an aqueous solution of a co-emulsifier such as a surfactant and alcohol and reacting them (microemulsion polymerization); A method of polymerizing a vinyl fluoride compound and a fluorinated olefin gas by reacting them (suspension polymerization), etc. In the present invention, a perfluorocarbon sulfonic acid resin precursor produced by any polymerization method can be used.

In addition, as the fluorine-containing hydrocarbon used in the polymerization solvent of solution polymerization, for example, trichlorotrifluoroethane or 1,1,1,2,3,4,4,5,5,5-decafluoropentane can be preferably used Alkanes and the like are collectively called "Flon (registered trademark)" compound group.

In the present invention, melt mass flow rate (MFR) can be used as an indicator of the degree of polymerization of the perfluorocarbon sulfonic acid resin precursor. The melt mass flow rate of the perfluorocarbon sulfonic acid resin precursor used in the present invention is preferably 0.01 or higher, more preferably 0.1 or higher, and still more preferably 0.3 or higher. Although the upper limit of the melt mass flow rate is not limited, the melt mass flow rate is preferably 100 or less, more preferably 10 or less, further preferably 5 or less. When the melt mass flow rate is less than 0.01 or greater than 100, molding such as film formation may become difficult.

The perfluorocarbon sulfonic acid resin precursor thus prepared is extruded using an extruder through a nozzle, a die, or the like. The molding method at this time and the shape of the molded body are not particularly limited. However, in order to increase the treatment rate in hydrolysis treatment and acid treatment described later, it is preferable that the molded body is in the form of pellets of 0.5 cm ³ or less.

Next, the perfluorocarbon sulfonic acid resin precursor molded as described above is immersed in an alkaline reaction liquid to be hydrolyzed.

The reaction solution used in this hydrolysis treatment is not particularly limited, but it is preferable to use an aqueous solution of an amine compound such as dimethylamine, diethylamine, monomethylamine, and monoethylamine or an aqueous solution of a hydroxide of an alkali metal or an alkaline earth metal, Particularly preferred are sodium hydroxide and potassium hydroxide. There is no particular limitation on the content of the hydroxide of alkali metal or alkaline earth metal. However, the content is preferably 10% by weight to 30% by weight. It is more preferable that the reaction liquid further contains swelling organic compounds such as methanol, ethanol, acetone, and DMSO. The content of the swelling organic compound is preferably 1% by weight to 30% by weight.

The treatment temperature varies depending on the type of solvent, the solvent composition, and the like, and the higher the treatment temperature, the shorter the treatment time. However, if the treatment temperature is too high, the perfluorocarbon sulfonic acid resin precursor will be dissolved or highly swelled, making it difficult to handle, so it is preferable to treat at 20°C to 160°C, and a more preferable treatment temperature is 40°C ~90°C. In addition, since it is preferable to hydrolyze all the functional groups that can be converted into SO ₃ H after hydrolysis, the longer the treatment time, the better. However, if the treatment time is too long, the productivity will decrease, so the treatment time is preferably 0.1 hours to 48 hours, more preferably 0.2 hours to 12 hours.

After the precursor of the perfluorocarbon sulfonic acid resin is hydrolyzed in the alkaline reaction solution, it is fully washed with warm water, and then acid-treated. The acid used in the acid treatment is not particularly specified, but is preferably inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as oxalic acid, acetic acid, formic acid, and trifluoroacetic acid, and more preferably a combination of these acids and water. mixture. In addition, two or more kinds of acids among the above-mentioned acids may be used in combination. By this acid treatment, the perfluorocarbon sulfonic acid resin precursor is protonated to become a SO ₃ H compound. The perfluorocarbon sulfonic acid resin obtained by protonation may be dissolved in a protic organic solvent or water, or may be dissolved in a mixed solvent of a protic organic solvent and water.

If the ion exchange capacity of the perfluorocarbon sulfonic acid resin used in the present invention is too high, the resulting solid polymer electrolyte membrane will swell significantly under high-temperature and high-humidity conditions during fuel cell operation, resulting in a decrease in strength. , wrinkling, so that the electrolyte membrane is peeled off from the electrode, etc., and the gas barrier property is also lowered. On the contrary, if the ion exchange capacity of the perfluorocarbon sulfonic acid resin used in the present invention is too low, then cause the power generation capacity of the fuel cell with the obtained solid polymer electrolyte membrane to decrease, therefore, the perfluorocarbon sulfonic acid resin The ion exchange capacity must be 0.5meq/g-3.0meq/g, and preferably 0.65meq/g-2.0meq/g, more preferably 0.8meq/g-1.5meq/g.

The polyazole compounds that can be used in the present invention will be described below.

Polyazole compounds (ingredient B) refer to polyimidazole compounds, polybenzimidazole compounds, polybenzimidazole compounds, polybenzoxazole compounds, polyoxazole compounds, polythiazole compounds and poly A polymer of a five-membered heterocyclic compound having one or more nitrogen atoms in the ring, such as a benzothiazole compound, may contain oxygen and/or sulfur in the ring in addition to nitrogen. At the same time, considering the solubility of polyazole compounds, among these compounds, preferably polyazole compounds having at least "-NH-" and/or "=N-" groups in the molecular structure, particularly preferably having at least "-NH-" based polyazole compounds.

In addition, among these polyazole compounds, the present invention selects a polyazole compound that is soluble in a protic solvent in which an alkali metal hydroxide is dissolved. For example, extremely large molecular weight polyazoles are insoluble in protic solvents in which alkali metal hydroxides are dissolved, and thus such polyazoles are not suitable. The molecular weight of the polyazole compound differs depending on its structure, but polyazole compounds with a weight average molecular weight of 300 to 500,000 are generally used.

In addition, if the polyazole compound is a five-membered heterocyclic compound with more than one nitrogen atom on the ring and p-phenylene, m-phenylene, naphthylene, fluorene ether, 6,6'- Polymerization of compounds formed by bonding divalent aromatic groups such as phenylsulfone, biphenylene, terphenylene, and 2,2-bis(4-carboxyphenylene)hexafluoropropane as repeating units material, heat resistance can be obtained, therefore, this polyazole compound is preferred, specifically, preferably polyazole compound composed of polybenzimidazole compound, more preferably poly[2,2' -(m-phenylene)-5,5'-dibenzimidazole] and the like.

In addition, an ion-exchange group can be introduced into the polyazole compound used in the present invention by employing a conventional modification method described below. The modified polyazole compound introduced with ion exchange groups refers to a polyazole compound introduced with at least one group such as amino group, quaternary ammonium group, carboxyl group, sulfonic acid group and phosphonic acid group. In addition, by introducing anionic ion-exchange groups into polyazole resins, the ion-exchange capacity of the entire electrolyte membrane can be increased, and as a result, high output can be obtained during fuel cell operation. Therefore, introducing anionic ion-exchange groups into polyazole resins It is effective. The amount of ion exchange groups introduced into the polyazole compound is preferably 0.1 meq/g to 1.5 meq/g in terms of ion exchange capacity. In addition, among these polyazole compounds, the present invention selects a polyazole compound that is easily soluble in a protic solvent containing an alkali metal hydroxide. However, among the above-mentioned polyazole-based compounds or the above-mentioned modified polyazole-based compounds, the present invention selects those polyazole-based compounds that are not easily soluble in water or hot water alone in the absence of an alkali metal. The reason is that after being processed into a film, under humid conditions, those polyazole compounds dissolved in water or hot water during the power generation process will cause the film to age after a period of time.

In addition, the above-mentioned polyazole-based compound and modified polyazole-based compound may be used alone, or any two or more thereof may be used in admixture.

There are no special regulations on the modification method of polyazole compounds. For example, oleum, concentrated sulfuric acid, sulfuric anhydride or its coordination compounds, sultones such as propane sultone, α-bromotoluenesulfonic acid or Chloroalkylphosphonic acid, etc., introduce ion-exchange groups on polyazoles, and when synthesizing monomers of polyazole compounds, make monomers have ion-exchange groups, and then carry out monomers with ion-exchange groups polymerization.

Examples of alkali metal hydroxides that can be used in the present invention include monovalent alkali metal hydroxides such as LiOH, NaOH, KOH, RbOH, CsOH and FrOH, wherein, from the solubility of polyazole compounds, preferred are NaOH and KOH.

Dissolving these perfluorocarbon sulfonic acid resins, polyazole compounds, and alkali metal hydroxides in a protic solvent to prepare the polymer electrolyte-containing solution of the present invention, the method for preparing the polymer electrolyte-containing solution , can be done by any method. For example, perfluorocarbon sulfonic acid resin, polyazole compound and alkali metal hydroxide can be added to the protic solvent at the same time, or these three substances can be added to the protic solvent in any order. However, in view of the solubility of the polyazole compound, a preferred method is to prepare in advance a protic solvent solution of a perfluorocarbon sulfonic acid resin and a protic solvent solution of a polyazole compound and an alkali metal hydroxide, The two protic solvent solutions are then mixed.

A particularly preferable method is to add and mix a solution of a perfluorocarbon sulfonic acid resin in a protic solvent to a solution of a polyazole compound and an alkali metal hydroxide in a protic solvent. If the order of addition is reversed, the polyazole compound may easily precipitate in a large size, resulting in unevenness of the entire system. In a film formed using such a polymer electrolyte-containing solution, the miscibility of the polyazole compound is lowered, and thus there is a tendency for the durability of the film to slightly decrease.

Next, the preparation method of the polymer electrolyte-containing solution of the present invention will be described. First, a method for dissolving a perfluorocarbon sulfonic acid resin in a protic solvent will be described.

Dissolve perfluorocarbon sulfonic acid resin protonated by acid treatment in a protic solvent.

There is no special regulation for the dissolution method, for example, the following methods can be enumerated: the perfluorocarbon sulfonic acid resin with ion exchange groups is added to a single solvent selected from water and the above-mentioned protic organic solvents or added to In the mixed solution of water and the above-mentioned protic organic solvent, make the solid content concentration of the perfluorocarbon sulfonic acid resin reach 1% by weight to 50% by weight, and then put it into an autoclave, and the autoclave can be used as required With a glass inner cylinder, replace the air in the autoclave with an inert gas such as nitrogen, and then heat the temperature in the autoclave to 50°C to 250°C under stirring for 1 hour to 12 hours. The higher the concentration of the perfluorocarbon sulfonic acid resin at this time, the more desirable it is in terms of yield. However, when the concentration of the perfluorocarbon sulfonic acid resin is increased, undissolved substances are likely to appear, so the concentration of the perfluorocarbon sulfonic acid resin is preferably in the range of 1% by weight to 40% by weight, more preferably 1% by weight to 30% by weight %, more preferably 3% by weight to 20% by weight.

In addition, as the solvent for dissolving the perfluorocarbon sulfonic acid resin, a single solvent selected from the aforementioned water and protic organic solvents can be used, and water alone is particularly preferable. A mixed solvent of two or more solvents may also be used. When a mixed solvent is used, a mixed solvent of water and a protic organic solvent is particularly preferable. As the protic organic solvent for dissolving the perfluorocarbon sulfonic acid resin, aliphatic alcohols are preferred, among which methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol are preferred , isobutanol and tert-butanol, etc., particularly preferred are methanol, ethanol, 1-propanol and 2-propanol.

The mixing ratio of water and protic organic solvent can be changed according to the dissolution method, dissolution conditions, type of perfluorocarbon sulfonic acid resin, solid content concentration of perfluorocarbon sulfonic acid resin, dissolution temperature, stirring speed, etc. the mixing ratio. When mixing water and a protic organic solvent, the mass ratio of the protic organic solvent relative to water is preferably 0.1 to 10 parts of the protic organic solvent per part of water, particularly preferably 0.1 to 5 parts per part of water Organic solvents.

When the solvent is only water, it is more effective to adopt a method of dissolving in an autoclave at an inner temperature of 130°C to 250°C. When this method is adopted, the decomposition product of the organic solvent can be reduced, the viscosity of the dissolved solution can be reduced, the system can be made more uniform, and the system can be treated at a high concentration.

Next, a method for dissolving a polyazole compound and an alkali metal hydroxide in a protic solvent will be described.

Preferably, the polyazole compound is dissolved using the above-mentioned protic solvent consisting of a mixture of a protic organic solvent and water. However, it is not limited to these protic solvents, as long as the affinity between the protic solvent and the polyazole compound used is good. As a preferable protic organic solvent for dissolving the polyazole compound, a solvent having a high boiling point is not preferable among the protic solvents in terms of production because such a solvent requires high temperature for removal. Preferred are solvents with a boiling point of 250°C or lower, more preferred are solvents with a boiling point of 200°C or lower, and particularly preferred are solvents with a boiling point of 120°C or lower. Particularly preferred are water and aliphatic alcohols, specifically, water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, and tert-butanol, etc. .

The dissolution temperature is preferably 10°C to 160°C, and more preferably 30°C to 90°C from the viewpoint of workability and the like. When the dissolution temperature is higher than the boiling points of water and the organic solvent, it is preferable to use an autoclave. In addition, it is preferable to perform this dissolution under stirring.

On the other hand, when dissolving the alkali metal hydroxide, the same solvent as dissolving the polyazole compound can be used.

In the present invention, the alkali metal hydroxide can be directly added to the solvent in which the polyazole compound is dispersed, or the solution of the alkali metal hydroxide can be added to the polyazole compound. For uniform mixing, the latter method is more preferred.

When mixing polyazole compounds and alkali metal hydroxides, the amount of alkali metal hydroxides to be added is preferably 1 equivalent to 100 double equivalent. When the amount of alkali metal hydroxide added is less than the preferred amount, there will be undissolved matter of polyazole compounds; when the amount of alkali metal hydroxide added is more than the preferred amount, although it can increase the Solubility of the compound, but precipitation of alkali metal hydroxides occurs. The amount of the alkali metal hydroxide to be added is more preferably 2 equivalents to 50 equivalents with respect to the total equivalents of nitrogen existing on the heterocyclic ring of the polyazole compound.

Regarding the composition of the mixed solution in which the polyazole compound and the alkali metal hydroxide are dissolved in the protic solvent, the protic organic solvent is preferably 10 to 500 parts by mass ratio relative to 1 part of the polyazole compound. , 0.05 to 50 parts of water. More preferably, the amount of the protic organic solvent is 20-400 parts, and the amount of water is 0.07-40 parts, and it is still more preferable that the amount of the protic organic solvent is 50-200 parts, and the amount of water is 0.1-20 parts.

When the amount of the protic organic solvent is small, undissolved matter of the polyazole compound appears and dispersibility deteriorates. When the amount of the protic organic solvent is too large, the concentration of the polyazole compound decreases, resulting in a decrease in production efficiency. The amount of water added may vary depending on the amount of alkali metal hydroxide added, and water may be added in the form of an aqueous solution of alkali metal hydroxide.

In the present invention, it is preferable to add a solution of the perfluorocarbon sulfonic acid resin described above to a mixed solution of a polyazole compound and an alkali metal hydroxide using a protic solvent produced as described above to obtain a polymer electrolyte-containing solution. solution, so the production procedure will be described below.

When the concentration of perfluorocarbon sulfonic acid resin in the polymer electrolyte-containing solution usable in the present invention is too high, precipitation of polyazole compounds occurs. Therefore, the concentration of the perfluorocarbon sulfonic acid resin solution used for mixing is preferably 1% by weight to 50% by weight, more preferably 2% by weight to 30% by weight, particularly preferably 3% by weight to 20% by weight. The mass ratio ((component A)/(component B)) of the perfluorocarbon sulfonic acid resin (component A) to the polyazole compound (component B) in the solution containing the polymer electrolyte is preferably 2.3 to 199, and further Preferably it is 5.6-199, Especially preferably, it is 19-199. In addition, in the solution containing the polymer electrolyte, the total mass of component A and component B is preferably 0.5% by weight to 30% by weight, more preferably 1% by weight to 25% by weight, and more preferably 3% by weight to 25% by weight. %.

The amount of alkali metal hydroxide added to the solution is not particularly specified, but in the composition of the mixed solution obtained by dissolving the added polyazole compound and alkali metal hydroxide in a protic solvent, relative to The number of equivalents of the nitrogen atoms in the polyazole compound and the amount of the alkali metal hydroxide are preferably adjusted within the range of 1 equivalent to 100 times the equivalent. When the amount of the alkali metal hydroxide added is too small, the polyazole The solubility of the paraffin compound decreases, and when the added amount of the alkali metal hydroxide is too large, the metal hydroxide precipitates in the solution or during film formation, resulting in a decrease in film strength. Especially in the case of many alkali metal oxides, the film-forming property will be greatly deteriorated, such as film thickness spots and film cracks, so the preferred addition amount of alkali metal hydroxide is to make the final mixed solution The amount of sulfonate in the perfluorocarbon sulfonic acid resin produced by reacting with the alkali metal hydroxide is 100% or less, preferably 80% or less, of the total sulfonic acid groups in the perfluorocarbon sulfonic acid resin component.

In addition, as described below, in the case of reducing or removing the alkali metal in the solution by treatment using an ion exchange resin or by dialysis treatment using an ion exchange membrane, the amount of the above-mentioned alkali metal hydroxide can be adjusted as follows, The alkali metal hydroxide added to the polyazole compound is dissolved in a protic solvent, and for the composition of the obtained solution, within the range that does not hinder the dissolution, the number of equivalents to the nitrogen atom in the polyazole compound, The number of equivalents of the alkali metal hydroxide is in sufficient excess. The degree of excess of the alkali metal hydroxide is preferably 1 equivalent to 10000 equivalents, more preferably 1 equivalent to 1000 equivalents, and still more preferably 1 equivalent to 100 equivalents. It is further preferable to adjust the amount of the above-mentioned alkali metal hydroxide as follows. The amount of acid salt is 100% or less, preferably 50% or less, more preferably 10% or less, and still more preferably 1% or less of the total sulfonic acid groups in the perfluorocarbon sulfonic acid resin component.

In addition, when the neutralization equivalent of sulfonic acid groups is 50% or more, since the amount of sulfonic acid effective for ion conduction decreases, in this case, it is preferable to acid-treat the membrane after the membrane is formed.

In addition, when adding the solution of perfluorocarbon sulfonic acid resin to the mixed solution of polyazole compound and alkali metal hydroxide, it is preferable to add it very slowly or add it under sufficient stirring to avoid local concentration distribution. .

In addition, in the present invention, in order to improve the homogeneity of the polymer electrolyte-containing solution containing a high concentration of perfluorocarbon sulfonic acid resin, it is preferable to add the solution of perfluorocarbon sulfonic acid resin to polyazole at least twice. In a mixed solution of a compound and an alkali metal hydroxide.

Specifically, it can be mixed through a first mixing step and a second mixing step, the first mixing step refers to dissolving the ion exchange group in a protic solvent in an amount of 0.5meq/g-3.0meq/g A solution obtained from a perfluorocarbon sulfonic acid resin (component A) is added to a polyazole compound (component B) and alkali metal equivalents of 1 to 100 times the equivalent of nitrogen atoms in the polyazole compound Hydroxide is dissolved in the solution obtained in the protic solvent, and make the mass ratio (A/B) of described component A and described component B be 1～198, carry out stirring and mixing then; Next, carry out described second Mixing step, in the solution obtained by the first mixing step, further add the solution obtained by dissolving the component A in a protic solvent, so that the final mass ratio of the component A to the component B (A /B) is 2.3-199, and the total mass of the component A and the component B is 0.5% by weight to 30% by weight, and then stirred and mixed.

In addition, it is also possible to use water with high solubility to perfluorocarbon sulfonic acid resin as the main protic solvent, thereby increasing the concentration of perfluorocarbon sulfonic acid resin in the solution, and the concentration of perfluorocarbon sulfonic acid resin The improved solution was added to the above mixed solution of polyazole compound and alkali metal hydroxide.

It is preferable to sufficiently stir when adding the solution, because a uniform dispersed solution can be obtained in this way. In addition, there is no special regulation on the stirring temperature, but if the temperature is too high, uneven precipitation of polyazole compounds will occur, and if the stirring temperature is too low, the viscosity will increase and uniform stirring will not be possible. Therefore, the stirring temperature is preferably -10°C ~100°C, more preferably 10°C to 50°C.

Compared with the prior art, for the polymer electrolyte membrane for solid polymer electrolyte fuel cells obtained by using the polymer electrolyte-containing solution of the present invention obtained in this way, since the polyazole compound in the membrane has high dispersibility, , is a film excellent in durability.

In addition, in the present invention, the polymer electrolyte-containing solution itself may be concentrated by any method. The concentration method is not particularly limited, and includes a method of evaporating the solvent by heating, a method of concentrating under reduced pressure, and methods such as pervaporation. In the case of using a mixed solvent of water and a protic organic solvent having a boiling point lower than that of water, the protic organic solvent can be distilled off by concentration to obtain a polymer containing a protic solvent mainly composed of water. electrolyte solution. In this case, in order to improve the filterability and film-forming properties of the polymer electrolyte-containing solution, it is preferable to add an appropriate protic organic solvent before actually forming a film.

As a result of concentration, if the total amount of the polyazole compound and the perfluorocarbon sulfonic acid resin in the resulting polymer electrolyte-containing solution is too large, the viscosity will increase and it will be difficult to handle. On the contrary, if the total amount is too high If there is little, the production efficiency will drop. Therefore, in the final solution containing polymer electrolyte, the total amount of polyazole compound and perfluorocarbon sulfonic acid resin is 0.5% by weight to 30% by weight, preferably 1% by weight to 30% by weight. 25% by weight, more preferably 2% to 20% by weight.

In addition, in order to prevent gelation (thickening) caused by volatilization of the protic solvent in the solution containing the polymer electrolyte, and to prevent gelation (thickening) over time during storage, It is also preferable to use at least one solvent selected from the group consisting of ethylene glycol, propylene glycol, glycerin, and derivatives thereof in a mixture of 50% by volume relative to the total protic solvent as the high-boiling point protic solvent.

In addition, the polymer electrolyte-containing solution that can be used in the present invention refers to a transparent solution in which a perfluorocarbon sulfonic acid resin and a polyazole compound are dissolved or finely dispersed, and the solution has no coarse substances visible to the naked eye, and Even when 20 ml of this solution was put into a glass vial and left to stand at 25° C. for 7 days, no precipitation layer or sediment was formed in the lower part of the vial. In addition, the viscosity of the solution containing the polymer electrolyte depends on the film forming device. When the method of casting the solution containing the polymer electrolyte on the membrane carrier and drying it while conveying is adopted, the viscosity is too high or too low. The desired film cannot be obtained, or spots appear on the film. Therefore, the viscosity of the polymer electrolyte-containing solution used in the present invention is preferably 2 cp to 10000 cp, more preferably 100 cp to 5000 cp, particularly preferably 500 cp to 3000 cp.

In the present invention, a state in which a part of the perfluorocarbon sulfonic acid resin reacts with a part of the polyazole compound (for example, a chemically bonded state such as a state in which an acid-base ion complex is formed by ion bonding) is preferable. As an example of the above state, sulfonic acid groups including perfluorocarbon sulfonic acid resins are ionically bonded to nitrogen in each reactive group such as imidazolyl, oxazolyl, and thiazolyl in polyazole compounds.

Whether a part of the perfluorocarbon sulfonic acid resin reacts with a part of the polyazole compound can be judged by using a Fourier-Transform Infrared Spectrometer (Fourier-Transform Infrared Spectrometer) (hereinafter referred to as FT-IR). Specifically, when the film of the present invention is measured by FT-IR, if the observed peak deviates from the original peaks of the perfluorocarbon sulfonic acid resin and polyazole compounds, it can be considered that the film in the perfluorocarbon sulfonic acid resin A state in which at least a part of the polyazole compound has reacted with a part of the polyazole compound. For example, in the case of using poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (hereinafter referred to as PBI) as the polyazole compound, it can be near 1458 cm ^-1 , An absorption peak shifted due to the chemical bonding between the sulfo group in the perfluorocarbon sulfonic acid resin and the imidazole group in PBI was observed around 1567 cm ⁻¹ or around 1634 cm ⁻¹ .

In addition, when using a dynamic viscoelasticity test to measure a chemically bonded film with these absorption peaks, the peak temperature (Tg) of the loss tangent value Tanδ obtained during the temperature rise from room temperature to 200°C, A shift towards higher temperatures compared to films without polyazole addition and without these absorption peaks. It is known that the Tg rises when the sulfonic acid group of the perfluorocarbon sulfonic acid resin is chemically bonded to metal ions or organic ions. Therefore, it can be considered that in the present invention, when the above-mentioned PBI is used as the polyazole compound, the nitrogen on the imidazole group in the PBI is chemically bonded to the sulfonic acid group of the perfluorocarbon sulfonic acid resin, and as a result This causes a part of the perfluorocarbon sulfonic acid resin as the main chain to be bound, resulting in an increase in Tg. That is, this chemical bond binds a part of the perfluorocarbon sulfonic acid resin, creating the effect of a cross-linking point, which contributes to improving water resistance and heat resistance and improving mechanical strength. Therefore, it is considered that this chemical bond ultimately has the effect of improving the durability of the battery during operation.

In the present invention, the solution of the polyazole compound and the perfluorocarbon sulfonic acid resin obtained by the above method is further treated with a cation exchange resin, thereby obtaining a polymer containing electrolyte solution. The polymer electrolyte-containing solution thus obtained is superior in solution long-term stability as compared with a solution not subjected to this treatment, and a film formed from such a polymer electrolyte-containing solution can be formed even if it is not further processed in a subsequent step. After the pickling process, it can also show excellent electrical characteristics.

The cation exchange resin used here is not particularly limited as long as it is a resin having cation exchange ability, but it is preferably a resin that does not substantially dissolve in a protic solvent used when preparing a solution containing a polymer electrolyte as described above. resin. In addition, in order to more effectively exhibit the ability to remove alkali metal components, it is more preferable that the cation exchange resin used is a strongly acidic cation exchange resin. Examples of such strongly acidic cation exchange resins include cation exchange resins having sulfonic acid groups in the resin, among which crosslinked cation exchange resins having sulfonic acid groups are particularly preferred.

The form of the cation exchange resin is not particularly limited, and examples thereof include gel-type, porous-type, highly porous and carrier-supported ion-exchange resins. In order to easily separate the cation exchange resin from the treated solution, it is preferable that the cation exchange resin is in the form of blocks or beads.

As more specific examples of these cation exchange resins, commercially available Diaion SK series, PK series, HPK25, etc. (manufactured by Mitsubishi Chemical Corporation), AmberlightIR120B, 200CT, etc. (manufactured by Organo Co.), and Dowex (manufactured by Dow Chemical Co.) etc.

In addition, two or more kinds of the above-mentioned cation exchange resins may be used sequentially or simultaneously.

As a method of treating a solution containing a polymer electrolyte with a cation exchange resin, for example, a method of adding a cation exchange resin to a solution containing a polymer electrolyte is included. In this case, the solution may be heated as necessary. In addition, it is more preferable to stir the solution, since this can increase the efficiency of removing alkali metal components. If the cation exchange resin is firmly combined with the alkali metal component and does not elute again, then the mixed solution in this state can also be used directly for membrane formation, but it is usually more preferable to separate the solution and ions after this treatment. Steps for exchanging resins. For the separation method, as long as it is a conventional method for separating solids and liquids, there are no special restrictions, and specific examples include: the method of recovering the supernatant by decantation; the method of filtering using filter paper, filter cloth, or porous filter; A method of separating by centrifugation, etc. Also, it is preferable to regenerate and reuse these cation exchange resins.

In addition to the above methods, for example, a method of forming a column filled with a cation exchange resin and passing a solution through the column is also preferable. In this case, in order to improve the treatment efficiency, the solution may also be conveyed under pressure.

The amount ratio of the cation exchange resin used and the solution to be treated is determined according to the degree of removal of the desired alkali metal component. In order to clarify the effect of the present invention, it is preferable to substantially remove the alkali metal component from the solution as far as possible, particularly preferably The alkali metal component is removed to a level at which the viscosity stability of the solution containing the polymer electrolyte and the film strength during film formation are not lowered. In this case, the equivalent number of the cation exchange resin is preferably 1 or more, more preferably 1.5 or more, and still more preferably 2 or more equivalents of the alkali metal component contained in the total amount of the solution to be treated.

In addition, dialysis treatment using a cation exchange membrane is also effective. The membrane used at this time may be a cation exchange membrane, and perfluorosulfonic acid membranes, perfluorocarboxylic acid membranes, styrenesulfonic acid membranes, and the like are preferably used. The dialysis method may be a dialysis method using a concentration difference, and is also preferably an electrodialysis method in which a potential is applied as needed between compartments separated by a cation exchange membrane.

In addition, the above-mentioned cation exchange resin treatment and dialysis treatment using a cation exchange membrane may be combined to perform treatment. In addition, depending on the situation, other known dialysis membranes (cellulose, parchment, etc.) can also be used to add an alkali metal equal to or more than the total equivalent of the azole component and the perfluorocarbon sulfonic acid component in the solution containing the polymer electrolyte. Components are removed, and the remaining alkali metal components are removed by dialysis of the ion exchange resin and/or the ion exchange membrane.

The solution containing the polymer electrolyte obtained in this way to reduce the alkali metal component or substantially remove the alkali metal component can be directly used for membrane formation, and can also be further concentrated or diluted as needed, or a combination thereof to adjust the solid state. concentration or solvent composition.

Next, a method of forming a film using the obtained polymer electrolyte-containing solution will be described.

The film-forming method includes: spreading a solution containing a polymer electrolyte in a container such as a petri dish, and heating it in an oven if necessary, thereby distilling off at least part of the solvent, and then peeling off the film formed on the container Wait to get membranous bodies. In addition, it is also possible to control the film thickness by using a doctor blade, an air knife or a reverse roller, etc., to control the film thickness, and pour the solution containing the polymer electrolyte on the glass. Sheets, films, etc., thereby forming a single coating film with uniform thickness. In addition, continuous casting and continuous film formation can also be used to make long film-like films.

In addition, an extrusion film-forming method in which a solution containing a polymer electrolyte is extruded from a die to form a film can also be used, and a single or long film can also be formed by this extrusion film-forming method. In addition, the solution can also be sprayed on a peelable carrier with a sprayer or the like, and the solution can be precipitated, and then dried to form a film, and then, if necessary, the film formed by drying can be processed by hot pressing. Consolidate into a film.

Furthermore, the film thickness may be controlled again with a doctor blade or an air knife before performing the drying treatment described later on the film obtained by cast film formation or extrusion film formation.

In addition, as a method of removing the solvent present in the film obtained by film formation, a method such as a solvent immersion method in which the film after film formation is put into an appropriate solution or solvent to remove the solvent can also be used. solvent method.

There is no regulation for the above-mentioned film-forming method, which can be selected in combination with the viscosity or other properties of the solution. In addition, it is also possible to form a film from solutions containing polymer electrolytes having different composition ratios a plurality of times by any method, and then laminate the formed films to form a multilayer film.

In addition, before film formation, it is preferable to pre-treat the solution containing the polymer electrolyte, such as vacuum defoaming or centrifugal separation to remove air bubbles, which is beneficial to control the film thickness. In order to easily remove air bubbles and make the film thickness uniform, a high-boiling solvent having a boiling point higher than that of water may be further added.

Alternatively, the polymer electrolyte-containing solution of the present invention may be impregnated into a woven, nonwoven, porous or fibrous reinforcing material having continuous pores to form a film. The membrane produced by the present invention itself has sufficient strength, but by adding the above-mentioned reinforcing material, it is possible to improve dimensional stability, degradation resistance, mechanical strength, and durability when operating a fuel cell at high temperature and high pressure. In addition, a multilayer film obtained by laminating an unreinforced layer and the above-mentioned reinforced layer by any method is also preferable.

Examples of the reinforcing material include polyethylene terephthalate (PET), polyethylene butyrate (PBT), polyethylene naphthalate (PEN), and liquid crystal polyesters. Polyester; triacetyl cellulose (TAC), polyarylate, polyether, polycarbonate (PC), polysulfone, polyethersulfone, cellophane, aramid, polyvinyl alcohol, polyethylene ( PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), acrylonitrile-butadiene-styrene copolymer (ABS), polymethyl methacrylate (PMMA), polyamide , polyacetal (POM), polyphenylene terephthalate (PPE), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyamideimide (PAI), Polyetheramide (PEI), polyetheretherketone (PEEK), polyimide (PI), polymethylpentene (PMP), polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene (FEP), tetrafluoroethylene Ethylene fluoride-ethylene (ETFE) copolymer, polyvinylidene fluoride (PVDF), polybenzazole (PBZ), polybenzoxazole (PBO), polybenzothiazole (PBT), polybenzimidazole (PBI) And polyparaphenylene terephthalimide (PPTA), etc. Other reinforcing materials include polysulfone (PSU), polyimide (PI), polyphenylene oxide (PPO), polyphenylene sulfoxide (PPSO), polyphenylene sulfide (PPS), polyphenylene sulfide Ethersulfone (PPS/SO2), polyparaphenylene (PPP), polyphenylquinoxaline (PPQ), polyarylketone (PK), polyetherketone (PEK), polyethersulfone (PES), polyether Ether sulfone (PEES), polyaryl sulfone, polyaryl ether sulfone (PAS), polyphenyl sulfone (PPSU) and polyphenylene sulfone (PPSO2), etc. As the polyimide, polyetherimide and fluorinated polyimide are preferable. As polyether ketone, polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone-ketone (PEKK), polyetherether ketone-ketone (PEEKK) and polyether ketone ether ketone-ketone (PEKEKK) are preferred . In addition, examples of inorganic reinforcing materials include basic magnesium, magnesium, magnesium borate, titanium diboride, graphite or alumina and their hydrates, silicon oxide, titanium oxide, silicon carbide, silicon nitride, nitride Any of boron, potassium titanate, aluminum borate, zinc oxide, and magnesium sulfate, and composite materials of these substances. In addition, in the present invention, the reinforcing material refers to a reinforcing material having an ion exchange capacity of 0.5 meq/g or less.

In the case of using these reinforcing materials, in order to improve the affinity and interfacial adhesion between the reinforcing material and the total resin components of component A and component B contained in the polymer electrolyte-containing solution of the present invention, or to improve the The impregnability of the polymer electrolyte solution, etc., can make the surface of the reinforcing material have sulfonic acid groups or amine groups and other ionic groups, or treat the reinforcing material with a coupling agent or the like. In addition, in order to improve the interfacial adhesion, ion exchange groups can also be uniformly introduced into part or all of the reinforcing material, for example, the reinforcing material has an ion exchange capacity of 0.5 meq/g or less.

When a porous material is used as the reinforcing material and the solution of the present invention is impregnated therein, since the higher the porosity, the ion conductivity of the membrane is higher, therefore, a reinforcing material with a high porosity is preferred in this case. However, if the porosity is too high, the reinforcing effect will be small, so the porosity is preferably 40% to 99%, more preferably 50% to 98%.

In addition, it is also possible to form a film after dispersing the short fibrous substance of the reinforcing material in the solution containing the polymer electrolyte of the present invention. In this case, the higher the aspect ratio (length/fiber diameter) of short fibers, the more effective it is for improving mechanical strength, suppressing dimensional changes in the planar direction when water is contained, and improving battery life during operation. Therefore, the aspect ratio of the short fibers is preferably 5 or more. In addition, as described above, when the short-fibrous reinforcing material is dispersed in a solution containing a polymer electrolyte to form a membrane, and the above-mentioned step of treating with a cation exchange resin is applied, it is preferable to disperse the reinforcing material in the Membrane formation is performed after the cation exchange resin is treated in a solution containing a polymer electrolyte.

At this time, if the reinforcing material component contained in the solution containing the polymer electrolyte is too much, the ionic conductivity will decrease, and the output during battery operation will decrease. Conversely, if the reinforcing material component contained in the solution is too small, the reinforcing effect will decrease. Therefore, it is preferable to set the total resin component of component A and component B to 45% by volume to 98% by volume relative to the total amount of component A, component B, and reinforcing material component contained in the solution containing the polymer electrolyte. %, more preferably 55% to 95% by volume, preferably 2% to 55% by volume of the reinforcing material component, more preferably 5% to 45% by volume.

In addition, the membrane in which the reinforcing material is dispersed can also be formed by dropping a solution obtained by dissolving another reinforcing material in a protic solvent at any stage in the production steps of the polymer electrolyte membrane of the present invention. Add to the solution containing the polymer electrolyte that the protic solvent used is a poor solvent for the reinforcing material, or conversely add the solution containing the polymer electrolyte dropwise to the solution obtained by dissolving the reinforcing material in the protic solvent In the obtained solution, the reinforcing material is phase-separated and precipitated in the form of fine fibers of arbitrary shapes. After the obtained mixed solution is uniformly dispersed and mixed, the poor solvent is preferentially retained, thereby maintaining the shape of the reinforcing material. Simultaneously, film formation and drying are performed by casting or spraying, thereby forming a film in which the reinforcing material is dispersed. In addition, the polymer electrolyte membrane of the present invention is more preferably a multilayer film obtained by laminating a reinforced layer and an unreinforced layer by any method. In this case, it is often preferred that an unreinforced layer is used as the skin layer in order to maintain the adhesion of the skin layer to the electrode.

In the present invention, the film formed by the above method is heated and dried at the following temperature.

After the membrane is desolvated by heating and drying, a dried membrane is obtained, that is, the polymer electrolyte membrane of the present invention suitable for use in a solid polymer electrolyte fuel cell is obtained.

The temperature of heat drying is preferably 40°C to 250°C. If the temperature is too high or the heating is too fast, air bubbles or thickness unevenness will occur during drying, so that a normal polymer electrolyte membrane with uniform film thickness accuracy cannot be obtained. Moreover, if this temperature is too low, drying time will become long, and production efficiency will fall. In addition, the heat drying may be divided into two stages or three stages, etc., and a method of obtaining a polymer electrolyte membrane with a uniform film thickness in the first stage and then further heating at a high temperature may be employed. According to this method, by lowering the drying temperature in the first stage and prolonging the drying time, a high-planar polymer electrolyte membrane without drying spots can be obtained.

Heat drying can be performed, for example under hot air or low-humidity air. Drying can be carried out in a state bound by a tenter frame or a metal frame or in a state without these restraints, for example, the film of the present invention can be placed on a carrier that does not adhere to the film for drying or floated by air flow, etc. method for drying.

The polymer electrolyte membrane suitable for use in solid polymer electrolyte fuel cells obtained by the above manufacturing method is heat-dried to form a homogeneous membrane. In addition, in the process of film formation, when the mechanical strength of the polymer electrolyte membrane is not enough, whether it is a continuous or a single film, a metal sheet or a metal belt can be used or polyethylene terephthalate, Films or tapes of polymer materials such as polyaramid, polyimide, polyethylene naphthalate, and polytetrafluoroethylene are used as easily peelable carriers.

The polymer electrolyte membrane suitable for use in solid polymer electrolyte fuel cells obtained by the above production method may be subjected to acid washing and/or water washing as necessary at any stage after film formation.

Pickling is the process of regenerating the ion exchange base by removing unnecessary metal ions and organic ions bound to the ion exchange base in the membrane. Therefore, when using, for example, a solution with a low degree of neutralization of sulfonic acid or a solution obtained by treating with the above-mentioned ion exchange resin, etc., the alkali metal component in the solution is reduced or the alkali metal component is substantially removed. If sufficient ion exchange capacity can be obtained without pickling, pickling is not necessary.

The acid used for pickling can be hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrogen peroxide, sulfonic acid, phosphinic acid and other inorganic acids alone, or tartaric acid, oxalic acid, acetic acid, formic acid, trifluoroacetic acid, aspartic acid , aminobenzoic acid, aminoethanesulfonic acid, inosine, glycerophosphate, diaminobutyric acid, dichloroacetic acid, cysteine, dimethylcysteine, nitroaniline, nitroacetic acid, picric acid, leather Colinic acid, histidine, bipyridine, pyrazine, proline, maleic acid, methanesulfonic acid, trifluoromethanesulfonic acid, toluenesulfonic acid and trichloroacetic acid and other organic acids, or these inorganic acids or organic acids Acid dissolved in water, methyl ethyl ketone, acetonitrile, propylene carbonate, nitromethane, dimethyl sulfoxide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, pyridine, methanol, ethanol and acetone, etc. The resulting solution was used. Among them, a solution obtained by dissolving an inorganic acid or an organic acid in water is particularly preferable.

Among these acids, an acid having a pH of 2 or less at 25°C is preferable. In addition, the temperature that can be used for washing is in the range of 0 to 160°C. However, if the washing temperature is too low, the reaction time will be prolonged. If the washing temperature is too high, sometimes the polyazole compound will be decomposed, and the perfluorocarbon The chemical bond between the sulfonic acid resin and the functional group of the polyazole compound is broken, resulting in loss of the durability improved by the chemical bond. Therefore, the treatment temperature is preferably 5°C to 140°C, more preferably 15°C to 80°C. In addition, when pickling is carried out at high temperature, it is preferable to use an autoclave having acid resistance.

In addition, since the membrane of the present invention uses a polymer electrolyte solution containing a protic solvent, the membrane of the present invention is characterized in that the membrane contains less Ion-exchange groups react firmly to impurities that are difficult to remove, and ion-exchange groups can be easily formed.

In addition, water washing can also be carried out as needed, especially in the case of pickling, water washing is carried out to remove the acid remaining in the film, but, in the case of no pickling, water washing can also be carried out to remove the acid remaining in the film. Impurities.

A particularly preferred solvent for washing is water, but various organic solvents having a pH of 1-7 can also be used. When washing with water, it is preferable to use a sufficient amount of pure water with an electrical conductivity of 0.06 μS/cm or less, and it is preferable to sufficiently wash with water until the pH of the washed water is 6-7.

The thus-obtained solid polymer electrolyte fuel cell electrolyte membrane (in the case of using the above-mentioned reinforcing material, the part where the reinforcing material is not present) was observed using a transmission electron microscope or a scanning electron microscope, and when the cross-section of the membrane was observed , it can be observed that a part of the particles mainly composed of polyazole compounds exists in the perfluorocarbon sulfonic acid resin, and the average particle diameter of the particles is less than 1 μm, and they are uniformly dispersed. If the average particle size of the particles is as large as 2 μm or more and the dispersion state is not uniform, the mechanical strength of such a film is insufficient, and microvoids are generated when used in a fuel cell, and these microvoids cause cross leakage of hydrogen gas and the like. In addition, the smaller the average particle size of the particles, the better, but technically it is difficult to make the particle size below 0.001 μm, so the more preferable particle size range is 0.005 μm to 0.7 μm, and more preferably 0.01 μm to 0.5 μm.

In addition, the polymer electrolyte membrane suitable for use in solid polymer electrolyte fuel cells of the present invention can be stretched under appropriate conditions by a known method after film formation, and the dimensional change during wetness can be reduced by stretching. In addition, it is also possible to obtain the same effect as stretching by drying in a restricted state after swelling. In addition, it is also possible to place the membrane before or after the regeneration of the ion exchange group by acid washing in an inert gas or air, or in any atmosphere where a crosslinking agent is present, at 100° C. to 250° C. The treatment is carried out for an arbitrary period of time to partially cause thermal crosslinking (reaction).

The polymer electrolyte membrane suitable for use in a solid polymer electrolyte fuel cell of the present invention, if the cation exchange capacity of the membrane is too high, swelling occurs during the operation of the fuel cell, resulting in a decrease in strength or wrinkling from the electrode. On the contrary, if the cation exchange capacity of the membrane is too low, the power generation capacity of the fuel cell will be reduced. Therefore, the cation exchange capacity of the membrane is 0.5 meq/g to 3.0 meq/g, preferably 0.65 meq/g to 2.0 meq/g, more preferably 0.8 meq/g to 1.5 meq/g.

In addition, regarding the thickness of the polymer electrolyte membrane suitable for use in the solid polymer electrolyte fuel cell of the present invention, if the thickness is too thin, the strength will decrease, and the electrolyte membrane is used to prevent the permeation of fuel such as hydrogen and oxygen or methanol. The role of barriers through which direct reactions occur is reduced. Conversely, if the thickness of the electrolyte membrane is too thick, the electrical conductivity decreases, resulting in a decrease in the power generation capability of the fuel cell. Therefore, the thickness of the electrolyte membrane is preferably 1 μm to 200 μm, more preferably 10 μm to 100 μm.

If the ion conductivity is too low, the power generation capability of the fuel cell will decrease, so the ion conductivity is 0.05 S/cm or more, preferably 0.10 S/cm or more, more preferably 0.15 S/cm or more.

Next, a method for manufacturing a membrane electrode assembly (MEA) using the polymer electrolyte membrane for a solid polymer electrolyte fuel cell of the present invention will be described.

The MEA is fabricated by joining electrodes to both surfaces of the polymer electrolyte membrane for a solid polymer electrolyte fuel cell of the present invention.

The electrodes are composed of fine particles of catalytic metal and a conductive material supporting the fine particles, and contain a water repellent as needed. The catalyst used in the electrode is not particularly limited as long as it is a metal that promotes the oxidation reaction of hydrogen and the reduction reaction by oxygen, and examples include platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, and cobalt. , nickel, chromium, tungsten, manganese, vanadium or alloys of these metals.

Among them, platinum is mainly used. As the conductive agent, any electron-conductive substance may be used, 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, and graphite, and these may be used alone or in combination.

As the waterproof material, a water-repellent fluorine-containing resin is preferable, and a waterproof material excellent in heat resistance and oxidation resistance is more preferable. Examples thereof include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer.

As such an electrode, a so-called electrode catalyst layer can be used as an electrode. The electrode catalyst layer is produced by dissolving a fluorine-based ion exchange resin as a binder in a mixed solution of alcohol and water, The carbon is dispersed in the binder to form a paste, and the paste is quantitatively coated on a polytetrafluoroethylene sheet, and then dried, thereby producing a so-called electrode catalyst layer.

In addition, for the fluorine-based ion exchange resin used as a binder at this time, a conventionally known perfluorocarbon sulfonic acid resin that can be used for an electrolyte membrane for a solid polymer electrolyte fuel cell can be used, and the present invention can also be used. A solution containing a polymer electrolyte is used as a binder.

When the electrolyte membrane for a solid polymer electrolyte fuel cell of the present invention is bonded to the above-mentioned electrodes to produce an MEA, specifically, the following method can be used.

Commercially available platinum-loaded charcoal (TEC10E40E, produced by Tanaka Precious Metals Co., Ltd.) was dispersed as a catalyst in the solution obtained by dissolving the perfluorocarbon sulfonic acid polymer in a mixed solution of alcohol and water to obtain a paste. This paste is applied to a polytetrafluoroethylene sheet to obtain an electrode, and the coated surfaces of the two electrodes thus obtained are opposed to each other, and the polymer electrolyte membrane for a solid polymer electrolyte fuel cell of the present invention is sandwiched therebetween, Bonding is then performed using, for example, thermocompression. The hot pressing temperature is 100°C to 200°C, preferably 120°C or higher, more preferably 140°C or higher. After bonding, the PTFE sheet is removed to form the MEA. Such a method for producing MEA is described, for example, in JOURNAL OF APPLIED ELECTROCHEMISTRY, 22 (1992), p.1-7. In addition, the production of the MEA is not limited to this method, and the MEA can be produced by applying an arbitrary solvent, electrolyte solution, etc., and then drying.

The MEA produced by the above method may also be used after forming a gas diffusion layer outside the outermost electrode catalyst layer.

As the gas diffusion layer, commercially available carbon cloth or carbon paper can be used. Examples of the gas diffusion layer include carbon cloth E-tek, carbon cloth B-1, CARBEL (registered trademark, manufactured by JAPAN GORE-TEX INC.), TGP-H (manufactured by Toray Industries, Inc.), and carbon paper 2050 (SPCTRACORP Co. manufacturing), etc.

In addition, a structure in which an electrode catalyst layer and a gas diffusion layer are integrated is called a gas diffusion electrode, and an MEA can be obtained even if the gas diffusion electrode is bonded to the polymer electrolyte membrane of the present invention. Examples of such a gas diffusion electrode include a gas diffusion electrode ELAT (registered trademark, produced by DE NORA NORTH AMERICA Co.).

From the obtained MEA, a solid polymer electrolyte fuel cell was manufactured in the procedure described below, and the cell was evaluated.

A solid polymer electrolyte fuel cell is composed of an MEA, a current collector, a fuel cell frame, a gas supply device, and the like. Among them, the current collector (bipolar plate) is a graphite or metal separator that has gas channels on the surface, etc., and not only transports electrons to an external load circuit, but also has channels that supply hydrogen and oxygen to the surface of the MEA. Function. By inserting MEA between such current collectors and performing multiple laminations, a fuel cell can be fabricated. As for the production method of the solid polymer fuel cell, for example, it is described in FUEL CELL HANDBOOK (VANNOSTRAND REINHOLD, A.J.APPLEBY et.al, ISBN 0-442-31926-6), and "Chemistry One Point, Fuel Cell (Second Edition )" (Taniguchi Masao, Meio Xuebian, Kyoritsu Publishing (1992)) and other methods.

A fuel cell operates by supplying hydrogen to one electrode and oxygen or air to the other electrode. The higher the operating temperature of the fuel cell is, the higher the activity of the catalyst is, so it is more preferable. However, generally, the fuel cell is operated at 50° C. to 100° C. where moisture can be easily controlled. The higher the supply pressure of oxygen and hydrogen, the higher the output of the fuel cell, so it is more preferable. However, when the supply pressure is high, the probability of contact between hydrogen and oxygen due to damage of the membrane increases, so it is preferable to adjust the supply pressure appropriately. pressure range.

The above is the method for producing a polymer electrolyte membrane suitable for a solid polymer electrolyte fuel cell of the present invention, the MEA having the electrolyte membrane for a solid polymer electrolyte fuel cell obtained by the production method, and the solid polymer electrolyte fuel cell explained.

The solution containing the polymer electrolyte used in the polymer electrolyte membrane for a solid polymer electrolyte fuel cell containing a perfluorocarbon sulfonic acid resin containing a polyazole compound of the present invention uses a protic solvent, and the polymer electrolyte membrane A solid polymer electrolyte fuel cell using an electrolyte membrane that has a perfluorocarbon sulfonic acid resin and does not contain a polyazole compound in the perfluorocarbon sulfonic acid resin, although a conventional protic solvent is used In contrast, a solid polymer electrolyte fuel cell using the electrolyte membrane of the present invention has high durability. In addition, compared with the conventional solid polymer electrolyte fuel cell using a polymer electrolyte membrane made of a fluorinated carbon sulfonic acid containing a polyazole compound and using an aprotic solvent, the electrolyte of the present invention is used Membrane solid polymer electrolyte fuel cells exhibit high initial power generation voltage and high power generation current. That is, a solid polymer electrolyte fuel cell using the electrolyte membrane for a solid polymer electrolyte fuel cell of the present invention can satisfy both performances of high initial power generation voltage and high durability.

Example

The present invention is illustrated in more detail by the following examples, but the present invention is not limited to these examples. The test methods for the respective physical properties in the present invention are as follows.

(1) Film thickness

The acid-type polymer electrolyte membrane was placed in a thermostatic chamber at 23° C. and 65% RH for 12 hours or more to equilibrate, and then measured using a film thickness gauge (manufactured by Toyo Seiki Seisakusho: B-1).

(2) Ion exchange capacity

Immerse an acid-type polymer electrolyte membrane of about 2cm ² to 10cm ² in 50ml of 25°C saturated NaCl aqueous solution, place it under stirring for 10 minutes, and use phenolphthalein as an indicator to perform neutralization titration with 0.01N sodium hydroxide aqueous solution . The Na-type polymer electrolyte membrane obtained after neutralization was washed with pure water, then vacuum-dried, and weighed after drying. The equivalent of sodium hydroxide used for neutralization was expressed as M (mmol), the weight of the Na-type polymer electrolyte membrane was expressed as W (mg), and the ion exchange capacity (meq/g) was calculated according to the following formula.

Ion exchange capacity = 1000/((W/M)-22)

(3) Melt mass flow rate (MFR)

According to JIS K-7210, the melt mass flow rate of the perfluorocarbon sulfonic acid resin precursor measured under the conditions of a temperature of 270° C. and a load of 2.16 kg is taken as MFR (g/10 min).

(4) Solid concentration

Accurately weigh the weight of the weighing bottle, and record its weight as W ₀ . After adding about 10 g of the test substance into the weighing bottle after weighing, it is accurately weighed, and the obtained weight is recorded as W ₁ . Dry the weighing bottle at 110°C and a vacuum of 0.10 MPa or less for more than 3 hours, then cool it in a desiccator equipped with silica gel, and when it reaches room temperature, weigh it accurately under the condition that it does not absorb water. , and denote the obtained weight as W ₂ . Express (W ₂ -W ₀ )/(W ₁ -W ₀ ) in percentage, and use this percentage as the solid content concentration. The above-mentioned measurement was carried out 5 times, and the average value was used as the solid content concentration.

(5) Determination of absorbance

After the solution to be measured is degassed, use a UV-VIS absorbance measuring device (produced by JASCO (Stock), V-550), take the absorbance of a quartz cuvette with an optical path length of 10mm in air as a blank, and use Add the measurement solution into the same cuvette, and measure the absorbance (ABS) of the solution at 850 nm. The light transmittance of the blank is recorded as I ₀ , and the light transmittance of the measured solution is recorded as I ₁ . At this time, the absorbance can be calculated by log(I ₁ /I ₀ ).

(6) Determination of ionic conductivity

A film sample was cut out in a wet state (immediately after being immersed in a hot water bath at a water temperature of 80° C. for 2 hours), and the thickness t was measured. The cut film sample was set in a two-terminal conductivity measuring cell for measuring the conductivity in the film longitudinal direction with a width of 1 cm and a length of 5 cm. This measuring cell was placed in ion-exchanged water at 80° C., and the resistance value r of the real part at a frequency of 10 kHz was measured by an AC resistance method, and the ion conductivity σ was derived from the following formula.

σ=l/(r×t×w)

σ: ionic conductivity (S/cm)

t: Thickness (cm)

r: resistance value (Ω)

l (=5): film length (cm)

W(=1): film width (cm)

(7) Determination of dispersion state

After embedding the polymer electrolyte membrane for solid polymer fuel cells to be measured in epoxy resin, use an ultramicrotome to cut ultrathin sections perpendicular to the membrane surface, and use a transmission electron microscope (H7100 produced by Hitachi) at an accelerating voltage of 125kV When it was observed under the hood, dispersed particles mainly composed of polyazole compounds in a dispersed state were observed. It should be noted that in the case of reinforcement materials, the evaluation is performed on the part without reinforcement materials. In addition, regarding the particle size, the average value of the long axis and the short axis perpendicular to the long axis was taken as the particle size, and the particles existing in the 100 μm square region were measured at at least three different locations, and the average value was calculated. Let this average value be an average particle diameter.

(8) Infrared absorption spectroscopic analysis

A film to be measured with a thickness of 10 μm to 60 μm was measured using an FT-IR absorbance measuring device (manufactured by JASCO Corporation, FT-IR460), and spectra at wavelengths from 4000 cm ⁻¹ to 800 cm ⁻¹ were measured.

(9) Determination of viscosity

Viscosity was measured at a measurement temperature of 25° C. using an E-type rotational viscometer (Toki Sangyo Co., Ltd. TV-20-cone and plate type) to measure the viscosity (cp) at 1 rpm.

(10) Determination of the amount of polyazole

The polyazole component in the polyazole solution is precipitated in a poor solvent of the polyazole solution such as water, washed sufficiently with the same poor solvent, and then sufficiently dried. After the polyazole component is fully pulverized, it is dissolved in a deuterium-substituted solvent capable of dissolving at a concentration of 0.5% to 1%, and the solution is analyzed by a Fourier Transform Nuclear Magnetic Resonance (Fourie Transform Nuclear Magnetic Resonance: FT-NMR, Japan Electronics Co., Ltd. (Co., Ltd. EX-270 FT-NMR) to determine its structure.

The nitrogen in the solution was quantified by organic elemental analysis (elemental analyzer, model YANAKO CHN CODERMT-5 (manufactured by Yanagimoto Co., Ltd.)), and the amount of polyazole resin in the solution was calculated according to the above-mentioned azole structure.

(11) Quantification of alkali metal hydroxide

Various samples were prepared by changing the amount of alkali metal hydroxide added to the solution containing the polymer electrolyte of the present invention, and these samples were analyzed with a plasma emission analyzer (ICPS-7000, manufactured by Shimadzu Corporation). Determination is carried out, and a standard curve of the concentration of the added alkali metal hydroxide and the absorbance is made. Then, the absorbance of the polymer electrolyte-containing solution of the present invention is measured, and the concentration of the polymer electrolyte-containing solution is determined according to a standard curve.

(12) Determination of water content

The water content in the polymer electrolyte-containing solution of the present invention was measured using a Carl-Fischer moisture meter (MKS-20, manufactured by Kyoto Denshi Kogyo Co., Ltd.).

(13) Determination of protic organic solvents

Protic solvents other than water in the polymer electrolyte-containing solution of the present invention were analyzed and quantified by a gas chromatograph (GC-14A, manufactured by Shimadzu Corporation).

(14) Measure the change of falling ball viscosity with time

The falling ball viscosity of the polymer electrolyte-containing solution of the present invention can be measured as follows. Specifically, let a ball with radius a and density ρ fall in a liquid with density ρ0. At this time, under a constant state, the ball falls at a constant speed. The falling ball viscosity η of the liquid is obtained from the falling velocity v of the ball after reaching this constant velocity by the following formula.

η=2a ² (ρ-ρ0)g/9v

where g is the acceleration due to gravity. In this example, a glass ball with a diameter of 5 mm and a weight of 0.165 g was used for the falling ball to measure the falling ball viscosity. Further keep the solution in an open state, and record the falling ball viscosity of the solution just prepared as η0, record the falling ball viscosity of the solution after standing for 1 day as η1, and use η1/η0 as the index of long-term viscosity stability, if If the value is 0.95-1.05, the solution is considered to be stable.

(15) Evaluation of fuel cells

The operation of a solid polymer electrolyte fuel cell using the polymer electrolyte membrane for a solid polymer electrolyte fuel cell of the present invention was evaluated by the following method. A polymer electrolyte membrane for a solid polymer electrolyte fuel cell is sandwiched between two gas diffusion electrodes, and hot-pressed at 160°C at a pressure of 50kg/cm ² to form an MEA. As the gas diffusion electrode, a gas diffusion electrode obtained by the following method was used. A 5% by weight perfluorosulfonic acid resin solution SS910 (manufactured by Asahi Kasei Co., Ltd., EW) was coated on a gas diffusion electrode ELAT (registered trademark) (Pt loading: 0.4 mg/cm ² ) produced by DE NORA NORTHAMERICA, USA. : 910, solvent composition (weight %): ethanol/water=50/50), in atmospheric atmosphere, carry out drying and fixing at 140 ℃, thus obtain described gas diffusion electrode (polymer load is 0.8mg/cm ² ).

This MEA was sandwiched between graphite separators having gas passages on the surface, assembled to an evaluation cell sandwiched by a metal fuel cell frame, and then mounted on an evaluation device. Specifically, under the conditions of using hydrogen as fuel, air as oxidant, and pressurizing both the anode side and the cathode side at 0.2 MPa (absolute pressure), the MEA was tested for single cell characteristics at a cell temperature of 100°C (initial voltage About 0.65V, current density 0.3A/cm ² ). Gas humidification is performed by water bubbling, both hydrogen and air are humidified at 60°C, and then hydrogen is supplied to the battery at a flow rate of 74cc/min on the anode side, and air is supplied to the battery at a flow rate of 102cc/min on the cathode side. At this time, the stability of the initial voltage, the height of the voltage, the decrease of the voltage with time, and the decrease of the power generation capacity due to the sudden drop of the voltage due to the leakage of hydrogen through the electrolyte membrane were observed. When the generated voltage drops to 0.25V, it will be regarded as the end point of operation. For those with good operation exceeding 1000 hours, the evaluation status at 1000 hours will be temporarily regarded as the evaluation result.

Each example and comparative example will be described below. And Table 1 collectively shows the physical property values of Examples and Comparative Examples.

[Example 1]

Use an extruder to melt and knead the perfluorocarbon sulfonic acid resin precursor, extrude it from a circular spinneret at 270 ° C, cool it with room temperature water, and then cut it into pellets to make a diameter of 2 mm to 3 mm. Cylindrical particles with a length of 4mm to 5mm. The perfluorocarbon sulfonic acid _{resin precursor is a fluoroethylene compound (CF 2 =} CF-O-(CF ₂ ) A copolymer (MFR=3) of ₂ -SO ₂ F) and a fluorinated olefin (CF ₂ =CF ₂ ) represented when Z in the general formula (2) is F. The perfluorocarbon sulfonic acid resin precursor particles were immersed in an aqueous solution having a KOH concentration of 15% by weight and a DMSO concentration of 30% by weight at 95°C for 6 hours to convert the above SO ₂ F into SO ₃ K.

After immersing the above-mentioned treated particles in 1N-HCl at 60°C for 6 _hours , wash them with ion-exchanged water at 60°C _, and then dry them to obtain the perfluoro Carbon sulfonic acid resin (ion exchange capacity of 1.39meq/g).

Then, the above-mentioned treated perfluorocarbon sulfonic acid resin, ethanol and water are added into the autoclave, wherein the solids concentration is 5% by weight, ethanol is 47.5% by weight, water is 47.5% by weight, and then under stirring, The mixture was treated at 180°C for 4 hours to obtain a homogeneous solution of perfluorocarbon sulfonic acid resin. This solution was referred to as perfluorocarbon sulfonic acid resin solution AS1.

100 g of pure water was added to 100 g of this perfluorocarbon sulfonic acid resin solution AS1, and after stirring, the solution was heated to 80° C., and the solution was concentrated to a solid concentration of 10% by weight while stirring. This perfluorocarbon sulfonic acid resin concentrated solution was referred to as AS2.

After 0.1 gram of polybenzimidazole (manufactured by SIGMA-ALDRICH JAPAN Co., weight-average molecular weight of 27,000, abbreviated as PBI) was sufficiently pulverized, 1 gram of 8% by weight of NaOH aqueous solution and 2 grams of ethanol were added thereto, and then, by Heat and stir at 80°C for 1 hour to fully dissolve the polybenzimidazole, then add 7.5 g of ethanol, and heat and stir at 80°C. Thus, polybenzimidazole was dissolved to obtain 10 g of reddish-brown polybenzimidazole solution. This solution was referred to as polyazole resin solution BS1.

A mixture of 10 g of perfluorocarbon sulfonic acid resin solution AS1 and 50 g of ethanol (special grade reagent produced by Wako Pure Chemical Industries, Ltd.) was added to 10 g of this polyazole resin solution BS1 to obtain a light reddish brown transparent solution. Under stirring, 84 g of the above-mentioned perfluorocarbon sulfonic acid resin concentrated solution AS2 was added to the transparent liquid. The dispersion solution thus obtained was a yellow transparent liquid.

The above-mentioned yellow transparent liquid was heated to 80° C. and concentrated under stirring so that the water content was 71% by weight, the amount of ethanol was 19% by weight, and the solid content concentration was 10% by weight. As a result, the obtained polymer electrolyte-containing solution was a yellow transparent liquid with an absorbance of 0.08. In addition, the viscosity was 1000 cp.

37.3 grams of the resulting polymer electrolyte-containing solution was evenly spread on a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, the petri dish was placed on a heating plate, and dried at 80° C. for 2 hours, and then further It is placed in a hot air oven and heat-treated at 180° C. for 1 hour.

After cooling, the obtained film was peeled off, and the film was pickled by immersing the film in 25° C. 2 mol/l aqueous HCl solution (manufactured by Wako Pure Chemical Industries) for 8 hours, and then ion-exchanged water was used to wash the film. After performing sufficient washing, it dried in the environment of 25 degreeC and 35 %RH.

The film thus obtained is a transparent film uniformly showing light brown, with a thickness of about 50 μm and an electrical conductivity as high as 0.23 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle size of PBI was 0.2 μm, and the particles were very uniformly dispersed.

In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. As in Comparative Example 1 described later, the generated voltage showed a stable voltage value of 0.64 V and was stable immediately after start-up. After more than 1000 hours, the power generation voltage of the fuel cell is still high, and the voltage after 1000 hours of operation is 0.60V. Since then, it still works and has not changed over time.

[Example 2]

In the same manner as in Example 1, a film after heat treatment at 180° C. for 1 hour was produced. After cooling, the film was peeled off from the petri dish, and the film was dipped in 1N trifluoroacetic acid aqueous solution (pH=0.6) at 25° C. for 8 hours to carry out pickling, and then sufficiently washed with ion-exchanged water, Then, it dried in the environment of 25 degreeC and 35 %RH.

The film thus obtained is a transparent film uniformly showing light brown, with a thickness of about 50 μm and an electrical conductivity as high as 0.23 S/cm. The dispersion state of the film produced in this way was the same as in Example 1.

In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. As in Comparative Example 1 described later, immediately after the start-up, the generated voltage showed a constant and good voltage value of 0.64 V, and was stable. The fuel cell operated well in the same manner as in Example 1, and the voltage after 1000 hours of operation was 0.58V.

[Example 3]

Use an extruder to melt and knead the perfluorocarbon sulfonic acid resin precursor, extrude it from a circular spinneret at 270 ° C, cool it with room temperature water, and cut it into pellets to make it with a diameter of 1 mm to 3 mm and a length of 4mm ~ 6mm cylindrical particles. The perfluorocarbon sulfonic acid resin precursor is a vinyl fluoride compound _{(CF 2 = CF- Copolymer ( MFR = 20 _} )constitute.

The perfluorocarbon sulfonic acid resin precursor particles were immersed in an aqueous solution having a KOH concentration of 15% by weight and a DMSO concentration of 30% by weight at 95°C for 6 hours to convert the above SO ₂ F into SO ₃ K.

After immersing the above-mentioned treated particles in 1N-HCl at 60°C for 6 _hours , washing with ion-exchanged water at 60°C and _drying , the perfluorinated Carbon sulfonic acid resin (ion exchange capacity of 1.11meq/g).

Then, the above-mentioned treated perfluorocarbon sulfonic acid resin, ethanol and water were added into the autoclave, wherein the solids concentration was 5% by weight, ethanol was 47.5% by weight, and water was 47.5% by weight. Then, under stirring, the The mixture was treated at 180°C for 4 hours, and naturally cooled under stirring to obtain a homogeneous solution of perfluorocarbon sulfonic acid resin. This solution was referred to as perfluorocarbon sulfonic acid resin solution AS3.

After adding 100 g of pure water to 100 g of this perfluorocarbon sulfonic acid resin solution AS3 and stirring, the solution was heated to 80° C. and concentrated to a solid content concentration of 10% by weight. This perfluorocarbon sulfonic acid resin concentrated solution was referred to as AS4.

After 0.1 g of polybenzimidazole (manufactured by SIGMA-ALDRICH JAPAN Co., weight-average molecular weight: 27,000, hereinafter referred to as PBI) was sufficiently pulverized, 7 g of 8% by weight NaOH aqueous solution and 4 g of ethanol were added, and then heated at 80° C. Stir for 1 hour to fully dissolve the polybenzimidazole, then add 15 g of ethanol, and heat and stir at 80°C. Thus, the polybenzimidazole was dissolved to obtain 23 g of a reddish-brown polybenzimidazole solution. This solution was called polyazole resin solution BS2.

A mixture of 23 grams of solution AS3 and 115 grams of ethanol (a special grade reagent produced by Wako Pure Chemical Industries, Ltd.) was added to 23 grams of this polybenzimidazole resin solution BS2 to obtain a light reddish-brown transparent solution. Under stirring, 80 g of perfluorocarbon sulfonic acid resin concentrated solution AS4 was added to the transparent liquid. The solution thus obtained was a yellow transparent liquid (dispersion solution).

The yellow transparent liquid prepared above was heated to 80° C., concentrated to a solid concentration of 10% by weight, a water content of 70% by weight, and an ethanol content of 20% by weight. In addition, the viscosity was 980 cp.

As a result, the obtained polymer electrolyte-containing solution was a yellow transparent dispersion solution and had an absorbance of 0.08.

37.3 g of the resulting solution containing polymer electrolytes was evenly spread on a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, the petri dish was placed on a heating plate, and dried at 80° C. for 2 hours, and then further It was placed in a hot-air oven and heat-treated at 180° C. for 1 hour.

After it was cooled, ion-exchanged water was added to the petri dish, and after the formed film was peeled off, it was peeled off, and the peeled off film was placed in a 1 mol/l aqueous HCl solution (manufactured by Wako Pure Chemical Industries) at 25°C. After immersion for 8 hours, it fully washed with ion-exchange water, and dried in the environment of 25 degreeC and 35 %RH after that.

The film obtained in this way is a uniformly light brown transparent film with a thickness of about 50 μm and an electrical conductivity as high as 0.18 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.2 μm, and the particles were uniformly dispersed. In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. As in Comparative Example 1 described later, immediately after starting up, the generated voltage showed a constant and good voltage value of 0.62 V, and was stable, and the fuel cell was able to operate well in the same manner as in Example 1. After 1000 hours of operation, The voltage is 0.59V.

[Example 4]

Except that in the mixture of 10 grams of perfluorocarbon sulfonic acid resin solution AS1 and 50 grams of ethanol (special grade reagent produced by Wako Pure Chemicals Co., Ltd.) prepared by the same method as in Example 1, add 10 grams of polyazole resin solution BS1, the addition method of AS1 and BS1 was the same as in Example 1 except that the addition method of AS1 and BS1 was reversed, and a solution containing a polymer electrolyte with a solid content concentration of 10% by weight was prepared. At this time, water was 70% by weight, and ethanol was 20% by weight. The obtained solution containing the polymer electrolyte was a yellow transparent liquid with an absorbance of 0.10.

37.3 grams of the above-mentioned solution containing polymer electrolytes were evenly spread in a petri dish made of SUS316 with a width of 20 cm × a length of 20 cm, the petri dish was placed on a heating plate, and dried at 80° C. for 2 hours, and then further It is placed in a hot air oven and heat-treated at 180° C. for 1 hour.

After it was cooled, ion-exchanged water was added to the petri dish, and the formed film was peeled off, and the peeled film was placed in a 1 mol/l aqueous HCl solution (manufactured by Wako Pure Chemical Industries) at 25°C. After immersion for 8 hours, it fully washed with ion-exchange water, and dried in the environment of 25 degreeC and 35 %RH after that.

The film thus obtained is a transparent film uniformly showing light brown, with a thickness of about 50 μm and an electrical conductivity as high as 0.23 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.3 μm.

In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Similar to Comparative Example 1 described later, the generated voltage showed a constant voltage value of 0.65V immediately after start-up, and was stable. The fuel cell was able to operate well for more than 1000 hours, and the voltage after 1000 hours of operation was 0.61V.

[Example 5]

1 gram of polybenzimidazole (produced by SIGMA-ALDRICH JAPAN Co., with a weight average molecular weight of 27,000) was fully pulverized, then added to 100 ml of 98% by weight sulfuric acid (produced by Wako Pure Chemical Industries, Ltd., special grade reagent), and heated at 100° C. Stir for 8 hours. The resulting solution was poured into an excess of ion-exchanged water to cause precipitation. The precipitate was collected, washed repeatedly with ion-exchanged water, and then dried at room temperature to obtain sulfonated polybenzimidazole. The amount of ion-exchange groups of this sulfonated polybenzimidazole was measured and found to be 1.06 meq/g.

Then, except that this sulfonated polybenzimidazole was used instead of polybenzimidazole to produce BS3, it carried out similarly to Example 1, and obtained the solution containing the polymer electrolyte which the solid content was concentrated to 10 weight%. The absorbance of this polymer electrolyte-containing solution was 0.08. In addition, using this polymer electrolyte-containing solution, a polymer electrolyte membrane was obtained in the same manner as in Example 1.

The film thus obtained was a transparent film uniformly showing a light brown color, having a thickness of about 50 μm, and an electric conductivity of 0.24 S/cm, which was higher than that of the case where no sulfonated polybenzimidazole was used. As a result of measuring the dispersion state of the film produced in this way, the average particle diameter was 0.2 μm.

In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. As in Comparative Example 1 described later, the generated voltage showed a constant voltage value of 0.66V immediately after startup, and was stable. The fuel cell was able to operate well for more than 1000 hours, and the voltage after 1000 hours of operation was 0.57V.

[Example 6]

0.1 gram of poly-p-phenylene benzobisoxazole (number-average molecular weight is 1000) is thoroughly pulverized, then immersed in a mixed solution of 1 gram of 8% by weight NaOH aqueous solution and 9.5 gram of ethanol, then heated and stirred at 80°C After 1 hour, a solution of poly-p-phenylenebenzobisoxazole was obtained. This solution was referred to as polyazole resin solution BS4. Except having used this BS4 instead of BS1 in Example 1, it carried out similarly to Example 1, and obtained the solid polymer electrolyte membrane.

The film thus obtained is a transparent film uniformly showing light brown, with a thickness of about 50 μm and an electrical conductivity as high as 0.23 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.2 μm, and the particles were very uniformly dispersed.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Similar to Comparative Example 1 described later, the generated voltage showed a constant voltage value of 0.63V immediately after start-up, and was stable. The fuel cell was able to operate well for more than 1000 hours, and the voltage after 1000 hours of operation was 0.55V.

[Example 7]

Operate in the same way as Example 3, make perfluorocarbon sulfonic acid resin solution AS3, and add 1000 gram of pure water in this perfluorocarbon sulfonic acid resin solution AS3 of 1000 gram, after stirring, this solution is heated to 95 °C while concentrating to a solid concentration of 30% by weight. This perfluorocarbon sulfonic acid resin concentrated solution was referred to as AS5. In addition, a polybenzimidazole solution BS1 (30 g) was produced by the same production method as in Example 1.

Then, the mixed solution of 30 grams of solution AS3 and 150 grams of ethanol (produced by Wako Pure Chemical Industries, Ltd., special grade reagent) was added in the above-mentioned BS1 solution to obtain a light reddish-brown transparent solution. Under stirring, 84 grams of perfluorocarbon sulfonic acid resin concentrated solution AS5 was added to the transparent liquid. The solution thus obtained was a yellow transparent liquid (dispersion solution).

The yellow transparent liquid prepared above was heated to 95° C. while concentrating to a solid content concentration of 20% by weight. As a result, the water content was 66% by weight, the amount of ethanol was 14% by weight, and the obtained polymer electrolyte-containing solution was a yellow transparent dispersion solution with an absorbance of 0.10.

Spread 18.6 grams of the above solution containing polymer electrolytes evenly in a SUS316 petri dish with a width of 20 cm x a length of 20 cm, place the petri dish on a heating plate, and dry it at 80°C for 2 hours, and then further dry it Put it in a hot air oven, and heat it for 1 hour at 180°C.

After cooling, ion-exchanged water was added to the petri dish, and the formed film was peeled off, and the peeled film was immersed in a 1 mol/l aqueous HCl solution (manufactured by Wako Pure Chemical Industries) at 25°C. Eight hours later, it was sufficiently washed with ion-exchanged water, and then dried in an environment of 25° C. and 35% RH.

The thus-obtained film was a transparent film having a uniform beige color, a thickness of about 50 μm, and an electric conductivity of 0.18 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.3 μm, and the particles were uniformly dispersed. In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Similar to Comparative Example 1 described later, the generated voltage showed a constant voltage value of 0.61V immediately after startup, and was stable. The fuel cell was able to operate well for more than 1000 hours, and the voltage after 1000 hours of operation was 0.55V.

[Example 8]

Using the same method as in Example 1, perfluorocarbon sulfonic acid resin solution AS1, perfluorocarbon sulfonic acid resin concentrated solution AS2, and polyazole resin solution BS1 were prepared.

Then, a mixed solution of 100 grams of solution AS1 and 500 grams of ethanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was added to 100 grams of polybenzimidazole solution BS1 to obtain a light reddish-brown transparent solution. Under stirring, 130 g of perfluorocarbon sulfonic acid resin concentrated solution AS2 was added to the transparent liquid. The polymer electrolyte-containing solution thus obtained was a yellow transparent dispersion solution with an absorbance of 0.11.

Spread 164 grams of the above-mentioned solution containing polymer electrolytes evenly in a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, place the petri dish on a heating plate, dry it at 80° C. for 2 hours, and then place it further Heat treatment was performed at 180° C. for 1 hour in a hot air oven.

After it was cooled, ion-exchanged water was added to the petri dish, and the formed film was peeled off, and the peeled film was placed in a 1 mol/l aqueous HCl solution (manufactured by Wako Pure Chemical Industries) at 25°C. After immersion for 8 hours, it fully washed with ion-exchange water, and dried in the environment of 25 degreeC and 35 %RH after that.

The thus-obtained film was a transparent film having a uniform beige color, a thickness of about 50 μm, and an electric conductivity of 0.20 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.4 μm, and the particles were uniformly dispersed. In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Similar to Comparative Example 1 described later, the generated voltage showed a constant voltage value of 0.62V immediately after start-up, and was stable. The fuel cell was able to operate well for more than 1000 hours, and the voltage after 1000 hours of operation was 0.57V.

[Example 9]

Using the same method as in Example 3, a perfluorocarbon sulfonic acid resin solution AS3 was prepared. Then, after sufficiently pulverizing 1 g of polybenzimidazole (hereinafter referred to as PBI. produced by SIGMA-ALDRICH JAPAN Co., with a weight average molecular weight of 27,000), 5 g of 8% by weight NaOH aqueous solution and 20 g of ethanol were added thereto, The polybenzimidazole was fully dissolved by heating and stirring at 80° C. for 1 hour, and then 160 g of ethanol was added and heated and stirred at 80° C. Then, polybenzimidazole was dissolved to obtain a reddish-brown polybenzimidazole solution. This solution was referred to as polyazole resin solution BS5.

Then, a mixed solution of 78 grams of solution AS3 and 390 grams of ethanol (produced by Wako Pure Chemical Industries, Ltd., special grade reagent) was added to the solution BS5 of 100 grams of polybenzimidazole to obtain a light reddish-brown transparent polyelectrolyte solution, the absorbance of the solution is 0.12.

Spread 477 grams of the above-mentioned solution containing polymer electrolytes evenly in a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, place the petri dish on a heating plate, and dry it for 2 hours at 80° C. Heat treatment was performed at 180° C. for 1 hour in a hot air oven.

After it was cooled, ion-exchanged water was added to the petri dish, and the formed film was peeled off, and the peeled film was placed in a 1 mol/l aqueous HCl solution (manufactured by Wako Pure Chemical Industries) at 25°C. After immersion for 8 hours, it fully washed with ion-exchange water, and dried in the environment of 25 degreeC and 35 %RH after that.

The thus-obtained film was a transparent film having a uniform beige color, a thickness of about 50 μm, and an electric conductivity of 0.17 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.4 μm, and the particles were uniformly dispersed. In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Similar to Comparative Example 1 described later, the generated voltage showed a constant voltage value of 0.61V immediately after start-up, and was stable. The fuel cell was able to operate well for more than 1000 hours, and the voltage after 1000 hours of operation was 0.57V.

[Example 10]

Perfluorocarbon sulfonic acid resin solution AS1 and polyazole resin solution BS1 were prepared in the same manner as in Example 1. 25 g of ethanol were added to 5 g of BS1, and after adding 92 g of AS1 to this ethanol solution, 31.5 g of water were added. The solution was concentrated to a solids concentration of 14%. 33 g of isopropyl alcohol (IPA) was added to this concentrated solution to obtain a polymer electrolyte-containing solution. Among them, the solid content concentration was 10.4% by weight, the water content was 63.7% by weight, and IPA, which is a protic solvent other than water, was 25.9% by weight.

61 grams of the resulting solution containing polymer electrolytes were evenly spread on a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, the petri dish was placed on a heating plate, and dried at 80° C. for 2 hours, and then further dried. Put it in a hot air oven, and heat it for 1 hour at 180°C.

The formed film was peeled off after cooling, and the peeled film was dipped in 25° C. 2 mol/l HCl aqueous solution (manufactured by Wako Pure Chemical Industries) for 8 hours to carry out pickling, and then, fully carried out with ion-exchanged water After washing, it dried in the environment of 25 degreeC and 35 %RH.

The thus-obtained film was a transparent film having a uniform beige color, a thickness of about 50 μm, and an electric conductivity of 0.23 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.2 μm, and the particles were very uniformly dispersed.

In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. As in Comparative Example 1 described later, immediately after startup, the generated voltage showed a constant voltage value and was stable, and the fuel cell was able to operate well for more than 1000 hours.

[Example 11]

Perfluorocarbon sulfonic acid resin solutions AS1 and AS2 and polyazole resin solution BS1 were produced in the same manner as in Example 1. 50 g of ethanol was added to 10 g of BS1, 10 g of AS1 was added to this ethanol solution, and then 84 g of AS2 was further added with stirring. The solution was concentrated to a solids concentration of 13%. 21 g of isopropyl alcohol (IPA) was added to this concentrated solution to obtain a polymer electrolyte-containing solution. Among them, the solid content concentration was 10.0% by weight, the water content was 66.7% by weight, and IPA, which is a protic solvent other than water, was 23.3% by weight.

61 grams of the resulting solution containing polymer electrolytes were evenly spread on a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, the petri dish was placed on a heating plate, and dried at 80° C. for 2 hours, and then further dried. Put it in a hot air oven, and heat it for 1 hour at 180°C.

The formed film was peeled off after cooling, and the peeled film was dipped in 25° C. 2 mol/l HCl aqueous solution (manufactured by Wako Pure Chemical Industries) for 8 hours to carry out pickling, and then, fully carried out with ion-exchanged water After washing, it dried in the environment of 25 degreeC and 35 %RH.

The film obtained in this way is a light brown transparent film uniformly, with a thickness of about 50 μm and an electrical conductivity as high as 0.22 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.15 μm, and the particles were very uniformly dispersed.

In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Similar to Comparative Example 1 described later, the generated voltage showed a constant voltage value of 0.63V immediately after startup, and was stable. The fuel cell was able to operate well for more than 1000 hours, and the voltage after 1000 hours of operation was 0.60V.

[Example 12]

Perfluorocarbon sulfonic acid resin solutions AS1 and AS2 and polyazole resin solution BS1 were produced in the same manner as in Example 1. 50 g of ethanol was added to 10 g of BS1, and 10 g of AS1 was added to the ethanol solution, and then 84 g of AS2 were added under stirring. The solution was concentrated to a solids concentration of 14%. 26 g of ethylene glycol (EG) was added to this concentrated solution to obtain a polymer electrolyte-containing solution. Among them, the solid content concentration was 10.0% by weight, the water content was 61.1% by weight, and EG, which is a protic solvent other than water, was 28.9% by weight.

61 grams of the resulting solution containing polymer electrolytes were evenly spread on a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, the petri dish was placed on a heating plate, and dried at 80° C. for 2 hours, and then further dried. Put it in a hot air oven, and heat it for 1 hour at 180°C.

The formed film was peeled off after cooling, and the peeled film was dipped in 25° C. 2 mol/l HCl aqueous solution (manufactured by Wako Pure Chemical Industries) for 8 hours to carry out pickling, and then, fully carried out with ion-exchanged water After washing, it dried in the environment of 25 degreeC and 35 %RH.

The film thus obtained is a transparent film uniformly showing light brown, with a thickness of about 50 μm and an electrical conductivity as high as 0.23 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.18 μm, and the particles were very uniformly dispersed.

In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Similar to Comparative Example 1 described later, the generated voltage showed a constant voltage value of 0.64V immediately after startup, and was stable. The fuel cell was able to operate well for more than 1000 hours, and the voltage after 1000 hours of operation was 0.60V.

[Example 13]

Perfluorocarbon sulfonic acid resin solutions AS1 and AS2 and polyazole resin solution BS1 were produced in the same manner as in Example 1. 25 g of ethanol was added to 5 g of BS1, and after adding 92 g of AS2 to the ethanol solution, 20.0 g of water was added. The solution was concentrated to a solids concentration of 13%. 13 g of n-butanol (NBA) was added to this concentrated solution to obtain a polymer electrolyte-containing solution. Among them, the solid content concentration was 10.9% by weight, the water content was 73.6% by weight, and NBA, which is a protic solvent other than water, was 15.5% by weight.

61 grams of the resulting solution containing polymer electrolytes were evenly spread on a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, the petri dish was placed on a heating plate, and dried at 80° C. for 2 hours, and then further dried. Put it in a hot air oven, and heat it for 1 hour at 180°C.

The formed film was peeled off after cooling, and the peeled film was dipped in 25° C. 2 mol/l HCl aqueous solution (manufactured by Wako Pure Chemical Industries) for 8 hours to carry out pickling, and then, fully carried out with ion-exchanged water After washing, it dried in the environment of 25 degreeC and 35 %RH.

The film thus obtained is a transparent film uniformly showing light brown, with a thickness of about 50 μm and an electrical conductivity as high as 0.23 S/cm. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter was 0.2 μm, and the particles were very uniformly dispersed.

In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. As in Comparative Example 1 described later, the generated voltage showed a constant and stable value immediately after start-up, and the fuel cell was able to operate well for more than 1000 hours.

[Example 14]

A porous membrane made of PVDF (manufactured by Millipore, Immobilon-P) was appropriately heated and stretched twice in length and width. The film thickness of the stretched PVDF film was about 120 μm, and the porosity of the porous film was calculated to be 92% based on the area and weight.

A mixed solution of 10 grams of perfluorocarbon sulfonic acid resin solution AS1 and 50 grams of ethanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was added to 10 grams of polyazole resin solution BS1 to obtain a light reddish-brown transparent solution. Under stirring, add 84 grams of perfluorocarbon sulfonic acid resin concentrated solution AS2 in this transparent liquid, then, in the solution that obtains, repeatedly dip above-mentioned porous membrane 5 times, after taking out finally, fix with metal frame, in this It was dried in a hot air oven at 80° C. for 2 hours in a fixed state, and then further heat-treated at 160° C. for 1 hour. After cooling, the formed film was removed from the metal frame, and the film was dipped in 25° C. 2 mol/l HCl aqueous solution (manufactured by Wako Pure Chemical Industries) for 8 hours to carry out pickling, and then, ion exchange After sufficiently washing with water, drying was performed in an environment of 25° C. and 35% RH.

Thus, an impregnated membrane having a film thickness of approximately 50 μm was obtained. The conductivity of the impregnated membrane was 0.19 S/cm.

The tear strength (g) of the film was measured using an Elmendorf light load tear strength tester (manufactured by Toyo Seiki Seisakusho) (n=3). While the tear strength of the conventional film (Aciplex S1002 manufactured by Asahi Kasei Co., Ltd.) was 2.2 g, this film showed a tear strength as high as 8.3 g.

[Example 15]

Perfluorocarbon sulfonic acid resin solution AS1, perfluorocarbon sulfonic acid resin concentrated solution AS2, and polyazole resin solution BS1 were prepared in the same manner as in Example 1. A mixed solution of 10 grams of perfluorocarbon sulfonic acid resin solution AS1 and 50 grams of ethanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was added to 10 grams of polyazole resin solution BS1 to obtain a light reddish-brown transparent solution. Under stirring, 84 g of perfluorocarbon sulfonic acid resin concentrated solution AS2 was added to the transparent liquid. Cut 1 gram of POLYFLON WEB PTFE fibers (fiber diameter 10 μm, fiber length 0.7 cm to 1 cm) produced by Daikin Corporation into fiber segments with an average fiber length of about 500 μm, and then fully disperse the fiber segments into the above solution, A solution containing a polymer electrolyte was obtained.

54.6 grams of the solution containing the polymer electrolyte obtained was evenly spread on a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, the petri dish was placed on a heating plate, and dried at 80° C. for 2 hours, and then further dried. Put it in a hot air oven, and heat it for 1 hour at 180°C.

The formed film was peeled off after cooling, and the peeled film was dipped in 25° C. 2 mol/l HCl aqueous solution (manufactured by Wako Pure Chemical Industries) for 8 hours to carry out pickling, and then, fully carried out with ion-exchanged water After washing, it dried in the environment of 25 degreeC and 35 %RH.

Use the Elmendorf light load tear strength tester (produced by Toyo Seiki Manufacturing Co., Ltd.) to measure the tear strength (g) (n=3) of the film. The tear strength of the existing film (Aciplex S1002 produced by Asahi Kasei Co., Ltd.) is 2.2 g, while the film showed a tear strength as high as 10.1 g.

[Example 16]

In the same manner as in Example 1, add a mixed solution of 10 gram perfluorocarbon sulfonic acid resin solution AS1 and 50 gram ethanol (produced by Wako Pure Chemical Industries, special grade reagent) in polyazole resin solution BS1 to obtain light reddish brown transparent liquid. Under stirring, 84 g of perfluorocarbon sulfonic acid resin concentrated solution AS2 was added to the transparent liquid. The dispersion solution thus obtained was a yellow transparent liquid.

The above-mentioned yellow transparent liquid was heated to 80°C, and concentrated under stirring, so that the water content was 70% by weight, the amount of ethanol was 19% by weight, and the solid content concentration was 11% by weight.

6 g of cation exchange resin (Diaion SK-1B type, manufactured by Mitsubishi Chemical Corporation) was added to this solution, and stirred slowly at room temperature for 1 hour. Then, the solution was suction-filtered using a PP membrane filter with a pore size of 10 μm (manufactured by Millipore Corporation), to obtain a yellow transparent polymer electrolyte-containing solution. The absorbance of the obtained solution was 0.01. In addition, the viscosity of the obtained solution was 1100 cP.

20 cc of the polymer electrolyte-containing solution prepared in the same manner was put into a glass vial with an opening diameter of 2 cm, and the initial falling ball viscosity η0 was measured without the cap. In addition, the falling ball viscosity η1 was measured after leaving the solution at room temperature for 1 day in an uncovered state. At this point, η1/η0 is 0.98, indicating that the viscosity of the solution is very stable.

36.7 grams of the solution containing the polymer electrolyte obtained was evenly spread on a petri dish made of SUS316 with a width of 20 cm x a length of 20 cm, the petri dish was placed on a heating plate, and dried at 80° C. for 2 hours, and then further dried. Put it in a hot air oven, and heat it for 1 hour at 180°C.

After cooling the film, it was peeled off, washed sufficiently with ion-exchanged water, and then dried in an environment of 25° C. and 35% RH.

The film obtained in this way is uniformly light brown transparent film with a thickness of about 50 μm, and the conductivity is as high as 0.24 S/cm although there is no acid treatment step. Moreover, the film was completely free from cracks and brittleness during heat treatment. The dispersion state of the film produced in this way was measured. As a result, the average particle diameter of PBI was 0.2 μm, and the particles were very uniformly dispersed.

In addition, the presence of chemical bonds (peak positions around 1458 cm ^-1 , around 1567 cm ^-1 and around 1634 cm ^-1 ) was confirmed by infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. As in Comparative Example 1 described later, immediately after the start-up, the generated voltage showed a constant and good voltage value of 0.65 V, and was stable. The fuel cell maintains a high power generation voltage after 1000 hours of operation, and the voltage after 1000 hours of operation is 0.62V. Therefore, the fuel cell can operate without changing with time. As a result of continuing to generate electricity for an extended period of time, even after 4000 hours, the voltage was still 0.54V.

[Example 17]

20 cc of the polymer electrolyte-containing solution made in the same manner as in Example 1 was packed into a glass vial with an opening diameter of 2 cm, and the initial falling ball viscosity η0 was measured in the uncovered state. In addition, the falling ball viscosity η1 was measured after the solution was left to stand at room temperature for 1 day without the lid covered. At this point, η1/η0 is 1.2, indicating that the viscosity tends to increase slightly.

[Comparative example 1]

Make solution AS2 (absorbance is 0.04) in the same manner as in Example 1, spread 37.3 grams of this solution evenly in the SUS316 petri dish made of wide 20cm * long 20cm, this petri dish is placed on the heating plate, at 80 ℃ After drying for 1 hour, it was further placed in a hot air oven and heat-treated at 180° C. for 1 hour.

After it was cooled, ion-exchanged water was added to the petri dish to peel off the formed film, which was then peeled off, and the peeled film was immersed in a 1 mol/l aqueous HCl solution (manufactured by Wako Pure Chemical Industries) at 25°C. Pickling was performed for 8 hours, and after that, it was sufficiently washed with ion-exchanged water, and then dried in an environment of 25° C. and 35% RH.

The film thus obtained was a uniform transparent film with a thickness of about 50 µm and an electrical conductivity of 0.24 S/cm. The dispersion state of the film produced in this way was measured. As a result, no particles were seen. In addition, the presence of chemical bonds (peak positions around 1458 cm ⁻¹ , 1567 cm ⁻¹ and 1634 cm ⁻¹ ) was not confirmed in infrared absorption spectroscopic analysis.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Immediately after start-up, the power generation voltage showed a constant value of 0.65V and was stable, and the fuel cell could operate well for up to 400 hours. However, the voltage dropped greatly during the power generation process, and finally the voltage dropped sharply to below 0.25V.

[Comparative example 2]

100 grams of perfluorocarbon sulfonic acid resin solution AS1 made in the same way as in Example 1 was dried under reduced pressure at normal temperature for 24 hours, then it was added in 45 grams of dimethylacetamide (DMAC) as an aprotic solvent, and mixed for 6 hours (becoming solution DS1). In addition, polybenzimidazole (produced by SIGMA-ALDRICH JAPAN Co., with a weight average molecular weight of 27000) and DMAC were added into the autoclave, sealed with a plug, kept at 200° C. for 5 hours, and then cooled to obtain a solid concentration of 10 wt. % solution (Solution ES1). Add 2 g of ES1 solution to 18 g of DS1 solution, and then vigorously stir at 120° C. for 6 hours to obtain a solution. The solution appeared cloudy, the solution was yellow, and its absorbance was 0.8.

The solution was coated on a tetrafluoroethylene film with a doctor blade to a coating thickness of about 500 μm. Then, it was dried at 100° C. for 2 hours, and the dried film was immersed in 1 mol/l sulfuric acid at 100° C. for 2 hours, and then dried in a 40° C. oven. The film thus obtained had a thickness of about 50 μm, and was cloudy and opaque yellow. The film had a low conductivity of 0.07 S/cm. In addition, the dispersion state of the film thus produced was measured, and as a result, the average particle diameter was 4.0 μm.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Immediately after start-up, the power generation voltage was low at about 0.46V, and fluctuated and was unstable. As in Comparative Example 1, the fuel cell was able to operate for 600 hours. Phenomenon, the voltage drops below 0.25V.

[Comparative example 3]

20 grams of the solution AS2 made in Example 1 was added to 200 grams of N-methylpyrrolidinedione (manufactured by SIGMA-ALDRICH JAPAN Co.), heated to 95°C for dehydration, and made into a solution with a solid concentration of 1% by weight. Solution FS1. Add polybenzimidazole (manufactured by SIGMA-ALDRICHJAPAN Co., weight average molecular weight is 27000) together with N-methylpyrrolidinedione into the autoclave, plug seal, keep warm at 200°C for 5 hours, then cool, Solution GS1 having a solid content concentration of 10% by weight was obtained.

The above FS1 and GS1 were mixed in a ratio of 40:1. The resulting solution was an opaque yellow solution with an absorbance of 0.83. This solution was put into a petri dish made of SUS so that the thickness of the solution was 4100 μm, and the petri dish was heated at 120° C. for 1 hour and at 140° C. for 1 hour to distill off the solvent. Then, after cooling the formed film to room temperature, add a small amount of ion-exchanged water to the film to float the film from the petri dish, peel off the film, and then heat the film in 2 mol/l hydrochloric acid at 80°C for 24 hours, and then washed in ion-exchanged water at 20°C for 24 hours.

The film thus obtained had a thickness of about 50 μm, and was cloudy and opaque yellow. The film had a low conductivity of 0.07 S/cm. In addition, the dispersion state of the thus-produced film was measured, and as a result, the average particle diameter was 2.3 μm.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Just after starting, the generating voltage is as low as about 0.45V, and fluctuates and is unstable. Although the battery can run for 500 hours, there is a sudden drop in the power generation voltage, which drops below 0.25V.

[Comparative example 4]

Based on the method described in Comparative Example 3 in Korean Laid-Open Patent Publication No. 2003-32321, a polymer electrolyte membrane having a perfluorocarbon sulfonic acid resin/PBI=97.5/2.5 (mass ratio) and a film thickness of 49 μm was produced as follows.

100 grams of perfluorocarbon sulfonic acid resin solution AS3 made in the same way as in Example 3 were dried under reduced pressure at normal temperature for 24 hours, then it was added in 45 grams of dimethylacetamide (DMAC) as an aprotic solvent, and mixed for 6 hours (as solution DS2). In addition, 10 grams of PBI used in Example 3 and 1 gram of LiCl were added to 90 grams of DMAC, then added to the autoclave, plugged and sealed, and stirred at 120 ° C for 6 hours to obtain 10% by mass of PBI /DMAC solution (ES2). 20 g of the above-mentioned perfluorocarbon sulfonic acid resin/DMAC solution was mixed in 0.5 g of this solution (ES2), followed by vigorous stirring at 120° C. for 6 hours to obtain a solution. The solution appeared cloudy and yellow, with an absorbance of 0.6. In addition, after standing still for 24 hours, a small amount of precipitate was found.

32 grams of this solution was spread in a stainless steel petri dish with a diameter of 15.4 cm, and dried in an oven maintained at 100° C. for 2 hours, and then heated to 150° C. for 6 hours of heat treatment. Thereafter, it was taken out from the oven, and after cooling, ion-exchanged water was added to the petri dish. After peeling off the formed film, it was peeled off, and the peeled film was immersed in a 1 mol/l HCl aqueous solution (manufactured by Wako Pure Chemical Industries) at 25° C. for 8 hours, then washed sufficiently with ion-exchanged water, and then placed in Dry in an environment of 25° C. and 35% RH.

The film thus obtained was cloudy and opaque yellow, had a thickness of about 50 μm, and an electric conductivity of 0.17 S/cm. As a result of measuring the dispersed state of the thus-produced film, the average particle diameter was 2.5 μm.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. As in the above-mentioned Comparative Example 1, the generated voltage showed a good voltage value of 0.61 V immediately after the startup, and was stable. Compared with Comparative Example 1, although this fuel cell was able to operate for a slightly longer time of 620 hours, it experienced a phenomenon of sudden voltage drop, which was considered to be caused by hydrogen leakage, and the generated voltage dropped below 0.25V.

[Comparative Example 5]

After 10 grams of PBI and 1 gram of LiCl used in Example 3 were added to 90 grams of DMAC, it was added to the autoclave, plugged and sealed, and stirred for 6 hours at 120° C. to obtain 10% by mass of PBI /DMAC solution (ES3). 40 g of perfluorocarbon sulfonic acid resin solution AS3 prepared in the same manner as in Example 3 was mixed with 0.5 g of this solution ES3. When mixed, a precipitate formed directly in the solution. The solution in this state was vigorously stirred at 120° C. for 6 hours to obtain a dispersion liquid. The dispersion appeared cloudy and pale yellow, and precipitates appeared at the bottom immediately after the stirring was stopped. Absorbance cannot be measured stably.

32 grams of the dispersion was spread on a stainless steel petri dish with a diameter of 15.4 cm, and dried in an oven maintained at 100° C. for 2 hours, and then heated to 150° C. for 6 hours of heat treatment. Thereafter, it was taken out from the oven, after cooling, ion-exchanged water was added to the petri dish, and the film was peeled off after the formed film was peeled off. (drug production) for 8 hours, washed sufficiently with ion-exchanged water, and then dried in an environment of 25° C. and 35% RH.

In the film obtained in this way, a large number of large (about tens of μm) precipitates visible to the naked eye were observed, the film was opaque light yellow, had a thickness of about 20 μm to 70 μm, and had large spots. The measurement deviation of ion conductivity is large and cannot be measured accurately.

After producing an MEA using this membrane, the MEA was assembled into a fuel cell single cell evaluation device, and a fuel cell characteristic test was performed using hydrogen and air. Immediately after starting, the power generation voltage is low, about 0.45V, and fluctuates greatly and is unstable. The fuel cell only runs up to 330 hours.

Table 1

A solution containing polymer electrolytes solid polymer electrolyte membrane Battery operation Absorbance Thickness (μ) Conductivity (S/cm) Average particle size (μ) Behavior of voltage at start-up Endurance time (hr) Example 1 0.08 about 50 0.23 0.20 Stable at the specified voltage (about 0.65V) More than 1000 Example 2 0.08 about 50 0.23 0.20 " " Example 3 0.08 about 50 0.18 0.18 " " Example 4 0.10 about 50 0.23 0.30 " " Example 5 0.08 about 50 0.24 0.20 " " Example 6 0.09 about 50 0.23 0.20 " " Example 7 0.10 about 50 0.18 0.30 " " Example 8 0.11 about 50 0.20 0.40 " " Example 9 0.12 about 50 0.17 0.40 " " Example 10 0.08 about 50 0.23 0.20 " " Example 11 --- about 50 0.22 0.15 " " Example 12 --- about 50 0.23 0.18 " " Example 13 --- about 50 0.23 0.20 " " Example 14 --- about 50 0.19 --- --- --- Example 15 --- about 50 --- --- --- --- Example 16 0.01 about 50 0.24 0.20 Stable at the specified voltage (yo 0.65V) More than 1000 Comparative example 1 0.04 about 50 0.24 none Stable at specified voltage (0.65V) 400 Comparative example 2 0.80 about 50 0.07 4.00 Lower than the specified voltage (0.39 ~ 0.46V), unstable 600 Comparative example 3 0.83 about 50 0.07 2.30 " 500 Comparative example 4 0.60 about 50 0.17 2.50 Stable at specified voltage (0.65V) 620 Comparative Example 5 Can't measure 20～70 Can't measure dozens Lower than the specified voltage (0.33 ~ 0.52V). Unstable 330

Industrial Applicability

The polymer electrolyte membrane obtained by the production method of the present invention is particularly effective as a polymer electrolyte membrane for a solid polymer electrolyte fuel cell under high-humidity and low-humidity conditions.

Claims (22)

1. A method for manufacturing a solid polymer electrolyte membrane, the method comprising a step of manufacturing a solution containing a polymer electrolyte and a film-forming step of forming a film from the solution containing a polymer electrolyte; In the solution manufacturing step, component A, component B and alkali metal hydroxide are dissolved in a protic solvent to produce a solution containing a polymer electrolyte. The component A has an ion exchange capacity of 0.5meq/g to 3.0meq/g The perfluorocarbon sulfonic acid resin of g, the component B is a polyazole compound, and in the manufactured solution containing the polymer electrolyte, the mass ratio (A/B) of the component A to the component B is: 2.3-199, the total mass of the component A and the component B is 0.5% by weight to 30% by weight. 2. The method for manufacturing a solid polymer electrolyte membrane according to claim 1, wherein the step of manufacturing the solution containing the polymer electrolyte comprises adding the whole polymer electrolyte with an ion exchange capacity of 0.5meq/g to 3.0meq/g A process of mixing the solution obtained by dissolving the fluorocarbon sulfonic acid resin in the protic solvent and the solution obtained by dissolving the polyazole compound and the alkali metal hydroxide in the protic solvent. 3. The method for manufacturing a solid polymer electrolyte membrane as claimed in claim 2, wherein the step of manufacturing the solution containing the polymer electrolyte comprises adding the full A process in which a solution obtained by dissolving a fluorocarbon sulfonic acid resin in a protic solvent is added to a solution obtained by dissolving the polyazole compound and the alkali metal hydroxide in a protic solvent. 4. The method for producing a solid polymer electrolyte membrane according to any one of claims 1 to 3, wherein the amount of the alkali metal hydroxide is 1 to 100 times equivalent. 5. The method for producing a solid polymer electrolyte membrane according to any one of claims 1 to 4, wherein in the step of producing the solution containing the polymer electrolyte, the ion exchange capacity is adjusted to 0.5 meq/g After ~3.0meq/g of perfluorocarbon sulfonic acid resin, the polyazole compound and the alkali metal hydroxide are dissolved in the protic solvent, the resulting solution is further treated with a cation exchange resin and / or dialysis using a cation exchange membrane. 6. The method for producing a solid polymer electrolyte membrane according to any one of claims 1 to 5, wherein, in the film forming step, after the film is formed, acid washing is further carried out, followed by water washing, and if necessary, heat treatment. 7. The method for producing a solid polymer electrolyte membrane according to any one of claims 1 to 6, wherein the perfluorocarbon sulfonic acid resin contains a repeating unit represented by -(CF ₂ -CF ₂ )- and a copolymer of repeating units represented by -(CF ₂ -CF(-O-(CF ₂ CFXO) _n -(CF ₂ ) _m -SO ₃ H))-, where X represents F or CF ₃ , and n represents An integer of 0 to 5, m represents an integer of 0 to 12, and n and m are not simultaneously 0. 8. The method for producing a solid polymer electrolyte membrane according to claim 7, wherein -(CF ₂ -CF(-O-(CF ₂ CFXO) _n -(CF ₂ ) _m -SO ₃ H))- n in the repeating unit represented is 0, and m is an integer of 1-6. 9. The method for manufacturing a solid polymer electrolyte membrane according to any one of claims 1 to 8, wherein the polyazole compound is selected from polyimidazole compounds, polybenzimidazole compounds, polybenzobis At least one compound selected from the group consisting of imidazole compounds, polybenzoxazole compounds, polyoxazole compounds, polythiazole compounds and polybenzothiazole compounds. 10. The method for producing a solid polymer electrolyte membrane according to claim 9, wherein the polyazole compound is a polybenzimidazole compound. 11. The method for producing a solid polymer electrolyte membrane according to any one of claims 1 to 10, wherein the protic solvent is mainly a mixed solvent of water and a protic organic solvent having a boiling point not higher than that of water. 12. The method for producing a solid polymer electrolyte membrane according to claim 11, wherein in the step of producing the polymer electrolyte-containing solution, the boiling point is once distilled off from the obtained polymer electrolyte-containing solution. The protic organic solvent not higher than the boiling point of water is prepared as a solution in which the solvent is a protic solvent mainly composed of water, and then the protic organic solvent is added again. 13. The method for producing a solid polymer electrolyte membrane according to any one of claims 1 to 12, wherein in the step of producing the polymer electrolyte-containing solution, a reinforcing material is further added to the protic solvent , and the added amount of the reinforcing material is 0.01% to 45% by volume of the total amount of the component A, the component B and the reinforcing material. 14. The method for producing a solid polymer electrolyte membrane according to claim 13, wherein the reinforcing material is a short fibrous substance having an aspect ratio of 5 or more. 15. The method for manufacturing a solid polymer electrolyte membrane according to any one of claims 1 to 14, wherein the film forming step includes impregnating the solution containing the polymer electrolyte into the solid polymer electrolyte membrane made of the reinforcing material. A process in a porous carrier with a porosity of 40% to 99%. 16. A solid polymer electrolyte membrane obtained by the production method according to any one of claims 1 to 15. 17. A multilayer solid polymer electrolyte membrane having at least one layer of the solid polymer electrolyte membrane as claimed in claim 16. 18. A membrane electrode assembly comprising the membrane of claim 16 or 17. 19. A solid polymer electrolyte fuel cell comprising the membrane electrode assembly of claim 18. 20. A solution containing a polymer electrolyte, which is obtained by dissolving component A, component B and alkali metal hydroxide in a protic solvent, wherein the component A has an ion exchange capacity of 0.5 meq/g to 3.0 The perfluorocarbon sulfonic acid resin of meq/g, the component B is a polyazole compound, in the solution containing polymer electrolyte, the mass ratio (A/B) of the component A to the component B 2.3-199, and the total mass of the component A and the component B is 0.5% by weight to 30% by weight. 21. A solution containing a polymer electrolyte, which is to further treat the solution containing a polymer electrolyte according to claim 20 with a cation exchange resin and/or use a cation exchange membrane for dialysis to make the alkali metal in the solution A solution containing a polymer electrolyte obtained by reducing or substantially removing alkali metals. 22. The solution containing polymer electrolytes according to claim 20 or 21, wherein the polyazole compound is selected from polyimidazole compounds, polybenzimidazole compounds, polybenzobisimidazole compounds, poly At least one compound selected from the group consisting of benzoxazole compounds, polyoxazole compounds, polythiazole compounds and polybenzothiazole compounds.