JP2016207609A - Composite polymer electrolyte membrane, manufacturing method therefor, membrane electrode assembly and fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte membrane having enhanced chemical durability against hydrolytic cleavage and peroxide radical under strong acid conditions, and to provide a membrane/electrode assembly using the polymer electrolyte membrane, and a fuel cell.SOLUTION: A porous base material is filled with a resin composition containing an aromatic polymer electrolyte of a repeated structure having a functional group in a molecular chain generating radical by an active energy beam, and further containing at least one selected from a radical polymerizable compound having a sulphonic acid, and a radical polymerizable compound of bifunctional or higher, and then polymerized by irradiation with an active energy beam thus producing a composite polymer electrolyte membrane, where the polymer electrolyte membrane contains 0.1-7.0 mass% of phosphorus atoms.SELECTED DRAWING: None

Description

The present invention relates to a composite polymer electrolyte membrane having excellent durability and proton conductivity and a method for producing the same.

Examples of electrochemical devices that use polymer solid electrolytes as ion conductors include water electrolyzers and fuel cells. The polymer membrane used for these must have high proton conductivity as a cation exchange membrane and be sufficiently stable chemically, thermally, electrochemically and mechanically. For this reason, a perfluorocarbon sulfonic acid membrane has been conventionally used as one that can be used for a long period of time. However, in polymer electrolyte fuel cell applications that are currently attracting particular attention, in addition to problems in characteristics such as high permeation of hydrogen gas, which is a fuel, since it contains fluorine, environmental pollution during disposal and power generation It has been pointed out that the hydrofluoric acid generated sometimes corrodes the fuel cell system.

On the other hand, as electrolyte membranes that replace perfluorocarbon sulfonic acid membranes, so-called hydrocarbon polymer solid electrolytes in which ionic groups such as sulfonic acid groups are introduced into polymers such as polyetheretherketone, polyethersulfone, and polysulfone have recently become popular. It is being considered. However, hydrocarbon-based polymer solid electrolytes tend to hydrate and swell compared to perfluorocarbon sulfonic acid, and have large dimensional changes, so there are problems with mechanical properties such as breakage due to repeated drying and wetting. It has been pointed out.

As a method for improving the mechanical strength of the hydrocarbon-based polymer solid electrolyte membrane, a method of crosslinking the electrolyte membrane can be mentioned. A crosslinked polymer electrolyte membrane obtained by reacting a radical polymerizable monomer in the presence of an initiator in the presence of a polyarylene electrolyte (see, for example, Patent Document 1), and a polymer electrolyte in which a proton conductive group is introduced into the polymer film Bifunctional triazine compounds, electrolyte membranes containing polyfunctional triazine compound precursors (see, for example, Patent Document 2), aromatic electrolytes having ionic groups, bis having two allyl groups in the molecule An electrolyte membrane (for example, see Patent Document 3) that has been heat-treated by adding a compound having a maleimide structure has been reported.

Furthermore, as a method of improving the mechanical strength of the polymer solid electrolyte membrane and suppressing the dimensional change, a composite polymer solid electrolyte membrane in which various reinforcing materials are combined with the polymer solid electrolyte membrane has been proposed. A polymer electrolyte membrane (for example, see Patent Document 4) in which a porous substrate is filled with a polymer having a functional group has been reported.

On the other hand, the hydrocarbon polymer electrolyte membrane has a problem that the chemical durability is inferior to that of the perfluorocarbon sulfonic acid polymer electrolyte membrane. In the hydrocarbon polymer electrolyte membrane, the polymer electrolyte membrane deteriorates due to hydrolysis under strong acid conditions. In a fuel cell using hydrogen as a fuel, it is considered that peroxide radicals are generated in the vicinity of an electrode during power generation and decomposition of the polymer electrolyte membrane occurs.

  In order to improve the chemical durability of hydrocarbon-based polyelectrolytes, chemical structures that are easily decomposed such as polyparaphenylene structures have been removed, and molecular structures that are easily decomposed such as ester, ether, and amide bonds have been eliminated. Hydrocarbon polymer electrolytes (for example, Patent Document 5) have been reported.

However, although this invention has been able to suppress membrane decomposition under strong acid conditions, it is still not sufficient in terms of durability against peroxide radicals.

As a technique for imparting durability to peroxide radicals, introduction of a phosphorus compound into a polymer electrolyte membrane (for example, Patent Document 6) has been reported.

JP 2003-82012 A JP 2007-335264 A Japanese Laid-Open Patent Publication No. 2007-63532 JP 2010-40530 A JP2015-38866A JP 2000-11755 A

  The present invention has been made against the background of such prior art problems. That is, an object of the present invention is to provide a polymer electrolyte membrane having improved chemical durability against hydrolysis and peroxide radicals under strong acid conditions, a membrane / electrode assembly using the polymer electrolyte membrane, and a fuel To provide a battery.

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have reached the present invention.
That is, this invention consists of the following structures.
A radical polymerizable compound having a repeating structure represented by the following chemical formula 1 and the following chemical formula 2 and further having a sulfonic acid, a radical polymerizable compound having a phosphonic acid, and a bifunctional or higher functional radical polymerizable compound A composite polymer electrolyte membrane obtained by filling a porous substrate with a resin composition containing at least one selected, and then polymerizing by irradiation with active energy rays, wherein the polymer electrolyte contains 0.1 to 7 phosphorus atoms. A composite polymer electrolyte membrane comprising 0% by mass.

Wherein R ¹ and R ² are any one of hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms, and R ¹ and R ² may be the same or different. R ³ represents either an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms which may have a substituent, and when R ³ has a substituent, the substituent is hydrogen. , Any one of an alkyl group having 1 to 20 carbon atoms and an aryl group having 6 to 20 carbon atoms, and when having a plurality of the substituents, the substituents may be the same or different. b represents an integer of 1 to 4. p and q are 0 or 1 satisfying p + q = 1.)

(In the formula, m and n are positive integers and m + n = 5 to 1000. R ⁴ is any one of hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. ^{May be the same} or different, r is 1 or 2, d is 4-r, A is OR ⁵ or N (R ⁶ ) (R ⁷ ), R ⁵ is hydrogen, An alkali metal, an alkyl group having 1 to 20 carbon atoms, R ⁶ and R ⁷ are either hydrogen or an alkyl group having 1 to 20 carbon atoms, and R ⁶ and R ⁷ may be the same May be different.)
(2) The composite polymer electrolyte membrane in which the polymer electrolyte contains 0.5 to 7.0% by mass of phosphorus atoms.
(3) A composite polymer electrolyte membrane, wherein the radical polymerizable compound having phosphonic acid is a compound represented by the following chemical formula 3.

(In the formula, R ⁸ is either hydrogen or an alkyl group having 1 to 20 carbon atoms. R ⁹ is any of a direct bond, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. T is any one of 1 to 5.) B represents OR ¹⁰ or N (R ¹¹ ) (R ¹² ), and R ¹⁰ is any one of hydrogen, an alkali metal, and an alkyl group having 1 to 20 carbon atoms. R ¹¹ and R ¹² are either hydrogen or an alkyl group having 1 to 20 carbon atoms, and R ¹¹ and R ¹² may be the same or different. )
(4) A composite polymer electrolyte membrane in which the radically polymerizable compound having phosphonic acid is vinylphosphonic acid.
(5) The composite polymer electrolyte membrane, wherein the porous substrate is made of a polymer material.
(6) The composite polymer electrolyte membrane, wherein the polymer electrolyte membrane has an ion exchange capacity of 1.5 meq / g to 6.0 meq / g.
(7) A polymer electrolyte membrane electrode assembly for a fuel cell using a composite polymer electrolyte membrane.
(8) A fuel cell using a polymer electrolyte membrane electrode assembly.

  According to the present invention, a peroxide radical is chemically stable by a phosphorus atom of a phosphonic acid compound copolymerized with an aromatic polymer electrolyte having a repeating structure represented by the following chemical formula 1 and the following chemical formula 2. Since it becomes a chemical species, decomposition of the composite polymer electrolyte membrane by peroxide radicals can be suppressed.

The present invention is described in detail below.
The aromatic polyelectrolyte in the present invention preferably has a functional group that generates radicals by active energy rays in its molecular chain, and the structure is not particularly limited. From the viewpoint of safety, it is preferable to have a repeating structure represented by Chemical Formula 1 and Chemical Formula 2.

Wherein R ¹ and R ² are any one of hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms, and R ¹ and R ² may be the same or different. R ³ represents either an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms which may have a substituent, and when R ³ has a substituent, the substituent is hydrogen. , Any one of an alkyl group having 1 to 20 carbon atoms and an aryl group having 6 to 20 carbon atoms, and when having a plurality of the substituents, the substituents may be the same or different. b represents an integer of 1 to 4. p and q are 0 or 1 satisfying p + q = 1.)

(In the formula, m and n are positive integers and m + n = 5 to 1000. R ⁴ is any one of hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. ^{May be the same} or different, r is 1 or 2, d is 4-r, A is OR ⁵ or N (R ⁶ ) (R ⁷ ), R ⁵ is hydrogen, An alkali metal, an alkyl group having 1 to 20 carbon atoms, R ⁶ and R ⁷ are either hydrogen or an alkyl group having 1 to 20 carbon atoms, and R ⁶ and R ⁷ may be the same May be different.)

Although m + n = 5 to 1000, when m + n <5, it is difficult to maintain the shape as the electrolyte membrane. On the other hand, m + n> 1000 is not easy to polymerize. More preferably, m + n = 10 to 500.

The ratio of m and n is not particularly limited, but is 0.95 / 0 in terms of m / n (molar fraction) from the viewpoint of proton conductivity and cross-linking reactivity after the formation of the composite polymer electrolyte membrane. 0.05 to 0.6 / 0.4 is preferable, and 0.9 / 0.1 to 0.75 / 0.25 is more preferable. These values can be obtained by a general method such as NMR.

The ion exchange capacity (IEC) of the aromatic polymer electrolyte having the structure represented by Chemical Formula 2 is not particularly limited, but may be 3.0 meq / g or more from the viewpoint of proton conductivity. However, if the IEC is too high, there is a problem that the swelling becomes large. Therefore, it is preferably substantially 3.0 to 8.4 meq / g, and more preferably 3.5 to 8.0 meq / g. 4.0-7.5 meq / g is most preferred.
Here, the ion exchange capacity is the amount of ion exchange groups introduced per gram of the dried polymer electrolyte membrane, and the larger the value, the greater the amount of ion exchange groups. For example, when a sulfonic acid group is used, it can be shown as a value of sulfonic acid group density (meq / g). The ion exchange capacity can be determined by capillary electrophoresis, elemental analysis, neutralization titration, and the like. Among these, it is preferable to obtain the ion exchange capacity by a neutralization titration method because of ease of measurement. A value measured by the neutralization titration method is used for the ion exchange capacity of the present invention, but other methods can be used without significant difference.

Ar ¹ and Ar ² in Chemical Formula ² preferably have structures represented by Chemical Formulas 3 and 4, respectively.

(In Chemical Formula 3, m and n represent the same meaning as defined in Chemical Formula 1. R ¹ and R ² are either hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. R ¹ and R ² may be the same or different, and R ³ is either an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms which may have a substituent. The substituent of R ³ is any one of hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms, and the substituents may be the same or different. , B represents an integer of 1 to 4. p and q are 0 or 1, and p + q = 1, wherein m represents the same meaning as defined in Chemical Formula 1. R ⁴ represents hydrogen, It is either an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and the substituent is the same. 1 or 2 .r may be different even, .A showing a d is 4-r represents an _{^{OR 5, NR 6 2, R}} 5 is hydrogen, an alkali metal, C1-20 And R ⁶ represents hydrogen or an alkyl group having 1 to 20 carbon atoms)

As the alkyl group having 1 to 20 carbon atoms among R ^{1 to} R ⁴ , a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, n-pentyl group, 2,2-dimethylpropyl group, n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-dodecyl group, n-tridecyl group N-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-icosyl group, 1,3-butadiene-1,4-diyl group, butane A -1,4-diyl group, a pentane-1,5-diyl group and the like can be mentioned. Examples of the aryl group having 6 to 20 carbon atoms include linear, branched, and cyclic groups such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 3-phenanthryl group, and a 2-anthryl group. However, it is not limited to these.

When R ¹ to R ⁴ are a plurality of ^each, to R 1 to R ⁴ it is good to be the same group or may be different groups.

In Chemical Formula 3, a and b are integers of 1 to 4, p and q are 0 or 1, and p + q = 1. That is, either p = 1 and q = 0 or p = 0 and q = 1.

In Chemical Formula 4, r is 1 or 2, d is 4-r, r is 1, and d is preferably 3.

In Chemical Formula 4, A is OR ⁵ , 80% or more of R ⁵ is hydrogen or an alkali metal, and preferably 90% or more is hydrogen or an alkali metal.

Hereafter, the manufacturing method of the aromatic polymer electrolyte of this invention is demonstrated.

As one of raw material compounds for producing an aromatic polymer electrolyte having a structure of Chemical Formula 2, a dihalobenzene compound which may have a substituent represented by Chemical Formula 5 is given.

(In the formula, X and Y are halogen atoms excluding fluorine, and X and Y may be the same or different. R ^{1 to} R ³ , a, b, p, and q have the same meaning as defined above. Represents.)

Specifically, 2,4-dichlorobenzophenone, 2,5-dichlorobenzophenone, 3,4-dichlorobenzophenone, 2,4′-dichlorobenzophenone, 4,4′-dichlorobenzophenone, 2,4 which may have a substituent, 2 , 4-dibromobenzophenone, 2,5-dibromobenzophenone, 3,4-dibromobenzophenone, 2,4′-dibromobenzophenone, 4,4′-dibromobenzophenone, but are not limited thereto.

Of these, 2,5-dichlorobenzophenone and 4,4′-dichlorobenzophenone which may have a substituent are preferable.

Furthermore, as one of raw material compounds for producing an aromatic polymer electrolyte having the structure of Chemical Formula 2, a dihalobenzenesulfonic acid ester which may have a substituent represented by Chemical Formula 6 may be mentioned.

(In the formula, X and Y are halogen atoms excluding fluorine, and X and Y may be the same or different. R ⁷ is hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. The substituents may be the same or different, s is 1 or 2, e is 4-s, B is represented by OR ¹³ or NR ¹⁴ ₂ , and R ¹³ Represents either hydrogen or an alkyl group having 1 to 20 carbon atoms, and R ¹⁴ represents either hydrogen or an alkyl group having 1 to 20 carbon atoms.)

Specifically, isopropyl 2,5-dichlorobenzenesulfonate, isobutyl 2,5-dichlorobenzenesulfonate, 2,5-dichlorobenzenesulfonate (2,2-dimethylpropyl), 2,5-dichlorobenzenesulfonate Cyclohexyl, n-octyl 2,5-dichlorobenzenesulfonate, n-pentadecyl 2,5-dichlorobenzenesulfonate, n-icosyl 2,5-dichlorobenzenesulfonate, isopropyl 3,5-dichlorobenzenesulfonate, 3 , Isobutyl 3,5-dichlorobenzenesulfonate, 3,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl), cyclohexyl 3,5-dichlorobenzenesulfonate, n-octyl 3,5-dichlorobenzenesulfonate, 3, 5-dichlorobenzenesulfone n-pentadecyl, n-icosyl 3,5-dichlorobenzenesulfonate, isopropyl 2,5-dibromobenzenesulfonate, isobutyl 2,5-dibromobenzenesulfonate, 2,5-dibromobenzenesulfonate (2,2-dimethyl) Propyl), cyclohexyl 2,5-dibromobenzenesulfonate, n-octyl 2,5-dibromobenzenesulfonate, n-pentadecyl 2,5-dibromobenzenesulfonate, n-icosyl 2,5-dibromobenzenesulfonate, 3 , 5-Dibromobenzenesulfonate isopropyl, 3,5-dibromobenzenesulfonate isobutyl, 3,5-dibromobenzenesulfonate (2,2-dimethylpropyl), cyclohexyl 3,5-dibromobenzenesulfonate, 3,5- Dibromobenzenesulfone n-octyl, n-pentadecyl 3,5-dibromobenzenesulfonate, n-icosyl 3,5-dibromobenzenesulfonate, 2,4-dichlorobenzenesulfonate (2,2-dimethylpropyl), 2,4-dibromo Examples include, but are not limited to, benzenesulfonic acid (2,2-dimethylpropyl).

Of these, 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl), isobutyl 2,5-dichlorobenzenesulfonate, and cyclohexyl 2,5-dichlorobenzenesulfonate are preferable.

When coupling polymerization is performed using the above raw materials, the polymerization can be performed with a catalyst system of a nickel compound, a ligand, and a reducing agent.

As nickel compounds, nickel (0) bis (cyclooctadiene), nickel (0) (ethylene) bis (triphenylphosphine), nickel (0) tetrakis (triphenylphosphine) and other zerovalent nickel compounds, nickel fluoride, Nickel halides such as nickel chloride, nickel bromide and nickel iodide, nickel carboxylates such as nickel formate and nickel acetate, nickel sulfate, nickel carbonate, nickel nitrate, nickel acetylacetonate, bis (triphenylphosphine) nickel dichloride Examples of the divalent nickel compound include, but are not limited to. Among these, nickel (0) bis (cyclooctadiene), nickel halide, and bis (triphenylphosphine) nickel dichloride are preferable.

The used amount of the nickel compound is preferably 0.01 to 500 mol% with respect to the monomer, and if the used amount of the nickel compound is too large, the molecular weight tends to decrease. Further, it is practically 100 mol% or less due to difficulty in purification and cost. On the other hand, if the amount is too small, the catalytic ability may be lost due to the influence of water present in the system, and it is practically 1 mol% or more. That is, 1 to 100 mol% is preferable.

Examples of the ligand include nitrogen-containing bidentate ligands and phosphorus ligands. Examples of the nitrogen-containing bidentate ligand include 2,2'-bipyridine, 1,10-phenanthroline, methylenebisoxazoline, N, N'-tetramethylethylenediamine, and 2,2'-bipyridine is preferable. On the other hand, as the phosphorus ligand, triphenylphosphine, tris (o-tolyl) phosphine, tris (m-tolyl) phosphine, tris (p-tolyl) phosphine, 1,2-bis (diphenylphosphino) ethane, 1, Examples include 3-bis (diphenylphosphino) propane, 1,4-bis (diphenylphosphino) butane, 1,4-bis (diphenylphosphino) butane, and 1,1′-bis (diphenylphosphino) ferrocene. However, it is not limited to these. Of these, triphenylphosphine, tris (o-tolyl) phosphine, tris (m-tolyl) phosphine, and tris (p-tolyl) phosphine are preferable. The amount of the ligand used is 0.5 to 8.0 equivalents, preferably 1.0 to 4.0 equivalents, of the nitrogen-containing bidentate ligand relative to the nickel compound.

Zinc can be used as the reducing agent, but is not limited thereto. The amount used is usually 1 equivalent or more with respect to the monomer, and there is no upper limit. Practically, in consideration of purification after polymerization, it is 5 equivalents or less, preferably 2 equivalents or less.

The polymerization solvent may be any solvent that can dissolve the monomer composition and the polyarylene to be produced. Specific examples of such solvents include aromatic hydrocarbon solvents such as toluene and xylene, ether solvents such as tetrahydrofuran and 1,4-dioxane, dimethyl sulfoxide, N-methyl-2-pyrrolidone, N, N-dimethylformamide. And aprotic polar solvents such as N, N-dimethylacetamide, and halogenated hydrocarbon solvents such as dichloromethane, dichloroethane, and chloroform, but are not limited thereto. A solvent may be used independently and may be used in mixture of 2 or more types. Of these, ether solvents and aprotic polar solvents are preferable, and tetrahydrofuran, dimethyl sulfoxide, N-methyl-2-pyrrolidone and N, N-dimethylacetamide are more preferable. When the amount of the solvent used is too large, polyarylene having a small molecular weight is easily obtained, and when the amount is too small, it is not preferable from the viewpoint of the solubility of the monomer composition and the resulting polyarylene. It is 1-200 weight times normally with respect to the monomer in a monomer composition, Preferably it is 5-100 weight times.

Usually, the reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen gas, but is not limited thereto. The polymerization time is 0.5 hours to 48 hours, and the reaction temperature can be from room temperature to the boiling point of the solvent, and is not particularly limited.

After the reaction, the polymer intermediate is synthesized by reprecipitation in an acidic aqueous solution and purification with an organic solvent. Purification is performed with a solvent that dissolves a compound other than the target polyarylene and does not dissolve the target polyarylene or is difficult to dissolve. The target polyarylene can be taken out by mixing the reaction mixture with the solvent to precipitate only the target polyarylene and performing filtration. The molecular weight and structure of the obtained polyarylene can be analyzed by ordinary analysis means such as gel permeation chromatography and NMR. Hydrochloric acid is preferable as the acidic aqueous solution, and examples of the organic solvent include alcohols such as methanol, ethanol and 2-propanol, acetone and acetonitrile, and 2-propanol and acetone are preferable.

Subsequently, a method for deprotection and acid conversion will be described.

The sulfonic acid ester is usually hydrolyzed with an acid or an alkali or reacted with an alkali metal halide or a quaternary ammonium halide, and then treated with an acid. The water-soluble polyarylene sulfonic acids produced this time are dissolved in an acid or alkaline aqueous solution when carried out by a usual method, and the desired polymer cannot be obtained.

Therefore, a method of reacting an alkali metal halide or amine hydrochloride and then acid-treating with a solid acid can be mentioned. Examples of the alkali metal halide include lithium bromide and sodium iodide. Examples of the amine hydrochloride include trimethylamine hydrochloride and triethylamine hydrochloride. Lithium bromide and trimethylamine hydrochloride are preferable. The amount used is 1.1 to 10 equivalents, preferably 2 to 8 equivalents, relative to the sulfonic acid ester in the polymer.

The solvent used for the reaction may be a condition that the deprotecting agent and the polymer are dissolved. Examples of such a solvent include aprotic polar solvents such as N-methylpyrrolidone. The reaction temperature is usually 0 to 200 ° C, preferably 80 to 160 ° C.

In the solution after the reaction, a polymer converted into an ammonium sulfonate type or a metal salt of sulfonic acid, a reaction residue of a deprotecting agent, and a reaction solvent are present, and thus purification is necessary. The solvent used for purification is a solvent in which the polymer converted to ammonium sulfonate type or sulfonic acid metal salt type does not dissolve and the reaction residue of the deprotecting agent dissolves, or converted to ammonium sulfonate type or metal sulfonate type. Therefore, a solvent in which the polymer is dissolved but the deprotectant reaction residue is not dissolved is required. A halogenated hydrocarbon solvent etc. are mentioned as a solvent in which the produced | generated polymer does not melt | dissolve but the reaction residue of a deprotecting agent melt | dissolves. Of these, chloroform is preferred.

As a method for acid-converting a polymer converted into an ammonium sulfonate type or a metal salt of sulfonic acid, a method using a solid acid can be mentioned. A cation exchange resin is preferred as the solid acid. The amount of the cation exchange resin used depends on the ion exchange capacity of the cation exchange resin, but since it is an equilibrium reaction, a considerable amount more than 10 times the ion exchange capacity of the target polymer is required. Although there is no particular upper limit, it is practically 20 times or less.

The target polymer can be produced by filtering the solid acid from the polymer aqueous solution in which the solid acid is dispersed, concentrating the polymer aqueous solution and drying.

  The compound having sulfonic acid and phosphonic acid in the present invention undergoes radical polymerization by active energy rays. Here, the active energy ray is not particularly limited as long as it can impart energy capable of generating an initial species in the radical polymerizable composition by irradiation, and α ray, γ ray, X ray, etc. High-energy radiation, ultraviolet rays, visible rays, infrared rays such as infrared rays, and particle beams such as electron beams are widely included. Among these, electron beam irradiation can cause a crosslinking reaction between secondary and tertiary carbons, and can form a high-density bridge with a polymer main chain and side chain, linear or cyclic aliphatic compound having a carbon-hydrogen bond. Since it can be expected, it is more preferable.

  The compound having sulfonic acid and phosphonic acid in the present invention is preferably radically polymerizable in order to suppress elution from the polymer electrolyte. Here, the radically polymerizable compound includes a compound that generates radicals upon irradiation with active energy rays and serves as a radical polymerization starting point.

  In the present invention, a vinyl sulfonic acid derivative, an allyl sulfonic acid derivative, a linear or cyclic aliphatic sulfonic acid derivative can be used as the radically polymerizable compound having a sulfonic acid, but from the viewpoint of polymerization reactivity, the vinyl sulfonic acid derivative and allyl. Sulfonic acid derivatives are preferred. Specific examples include vinyl sulfonic acid, 4-styrene sulfonic acid, and salts thereof.

  In the present invention, vinyl phosphonic acid derivatives and allyl phosphonic acid derivatives and linear or cycloaliphatic phosphonic acid derivatives can be used as radically polymerizable compounds having phosphonic acid, but from the viewpoint of polymerization reactivity, vinyl phosphonic acid derivatives and allyl. Phosphonic acid derivatives are preferred. Specifically, vinyl phosphonic acid, 4-styrene sulfonic acid, 4-vinyl benzyl phosphonic acid, allyl phosphonic acid, allyl phosphonic acid allyl salt thereof, methyl vinyl phosphonate, ethyl vinyl phosphonate, dimethyl vinyl phosphonate, vinyl phosphone Examples include diethyl acid, methyl allyl phosphonate, ethyl allyl phosphonate, dimethyl allyl phosphonate, diethyl allyl phosphonate, diallyl allyl phosphonate, vinyl phosphonic acid having excellent electrochemical characteristics of the polymer electrolyte membrane, 4- Styrenesulfonic acid, 4-vinylbenzylphosphonic acid, and allylphosphonic acid are more preferable.

Durability to peroxide radicals is improved by increasing the amount of radically polymerizable compound having phosphonic acid, while proton conductivity is lowered. In order to achieve good durability with a radically polymerizable compound having a smaller amount of phosphonic acid, it is preferable that the polymer electrolyte has a chemical structure with high oxidation resistance. More specifically, perfluoropolymer electrolyte and aromatic polymer electrolyte are preferable.

  In order to obtain a chemical durability effect by the amount of the radically polymerizable compound having phosphonic acid in the present invention, the amount of phosphorus atom in the polymer electrolyte needs to be 0.1% by mass or more. Although it will not specifically limit as long as the electrochemical characteristics and chemical durability which depend on a use are satisfy | filled, the range of phosphorus atomic weight is preferable 0.1-7.0 mass%.

In particular, in fuel cell applications using hydrogen as a fuel, the amount of phosphorus atoms in the polymer electrolyte is preferably in the range of 0.5 to 7.0% by mass, more preferably 1.0 to 6.0% by mass. 0 to 4.0 is most preferred. If the amount of phosphorus atoms is less than 0.5% by mass, the polymer electrolyte is decomposed by peroxide radicals, and if it exceeds 7.0% by mass, the power generation performance of the fuel cell decreases due to a decrease in proton conductivity.

The crosslinking agent having a bifunctional or higher radical polymerizable functional group in the present invention is preferably trifunctional or higher from the viewpoint of crosslink density. Further, from the viewpoint of hydrolysis resistance, a cross-linking agent having no easily decomposable molecular structure such as ester or ether bond is more preferable. Specific examples include 1,3,5-triacryloylhexahydro-1,3,5-triazine, triallyl isocyanurate, trimethallyl isocyanurate, and derivatives and reactants thereof.

The material of the porous base material used in the present invention is not particularly limited as long as it does not block or interfere with proton conduction, but in view of heat resistance and physical strength reinforcement effect, An aromatic polymer, an aromatic polymer, or a fluorine-containing polymer is preferably used. Examples of the aliphatic polymer include, but are not limited to, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and ethylene-vinyl alcohol copolymer. In addition, polyethylene here is a general term for ethylene-based polymers having a polyethylene crystal structure. For example, in addition to linear high-density polyethylene (HDPE) and low-density polyethylene (LDPE), ethylene and other polymers are used. It also includes a copolymer with a monomer, and specifically includes a copolymer with ethylene and α-olefin, which is called linear low density polyethylene (LLDPE), and an ultrahigh molecular weight polyethylene. Polypropylene as used herein is a general term for polypropylene-based polymers having a polypropylene crystal structure, and generally used propylene-based block copolymers, random copolymers, etc. (these are copolymers with ethylene, 1-butene, etc.). Which is a polymer).

Examples of the aromatic polymer include polyphenylene sulfide, polyethersulfone, polysulfidesulfone, polyethylene terephthalate, polycarbonate, polyimide, polyetherimide, polyetherketone, polyetheretherketone, polyphenyleneoxide, aromatic polyamide, and polyamideimide. Is mentioned. Furthermore, cellulose and polylactic acid can also be used.

As the fluorine-containing polymer, a thermoplastic resin having at least one carbon-fluorine bond in the molecule is used, but all or most of the hydrogen atoms of the aliphatic polymer are substituted with fluorine atoms. Those having a different structure are preferably used. Specific examples thereof include polytrifluoroethylene, polytetrafluoroethylene, polychlorotrifluoroethylene, poly (tetrafluoroethylene-hexafluoropropylene), poly (tetrafluoroethylene-perfluoroalkyl ether), and polyvinylidene fluoride. Although it is mentioned, it is not limited to these. Of these, polytetrafluoroethylene and poly (tetrafluoroethylene-hexafluoropropylene) are preferable, and polytetrafluoroethylene is particularly preferable. These porous materials may be used alone or in combination with other materials.

When a porous film is selected as the porous material, an aliphatic polyolefin film typified by polyethylene or polypropylene is preferable from the viewpoint of electrochemical stability and cost.

Also, a process of adding an extractable to polyolefin, finely dispersing it, forming a sheet, extracting the extractable with a solvent or the like to form pores, and performing a stretching process before and / or after extraction as necessary. The porous material obtained by the wet method obtained by the extraction method which has can also be used. In addition, a porous material opened in a honeycomb shape by self-organization or a film made porous by stretching by adding a pore-forming agent such as calcium carbonate can be used.

The porosity of the porous substrate is appropriately determined experimentally depending on the ion exchange capacity of the polymer electrolyte to be used. From the viewpoint of proton conductivity of the composite polymer electrolyte membrane and ease of filling the polymer electrolyte solution, 30% or more and 90% or less are preferable, and 35% or more and 70% or less are more preferable. When the porosity is 35% or more, the polymer electrolyte solution can be easily filled up to the inside of the porous material, and the proton conduction path is easily formed continuously in the thickness aroma of the composite polymer electrolyte membrane. Moreover, if it is 90% or less, the workability | operativity in a film forming process will become favorable, and the reduction | decrease of the mechanical strength at the time of the wet / dry dimensional change of a composite polymer electrolyte membrane and water absorption can be suppressed.

The porosity of the porous substrate is obtained from the following equation by cutting the porous material into squares, measuring the length of one side L (cm), weight W (g), and thickness D (cm). Can do.
Porosity = 100-100 (W / ρ) / (L2 × D)
Ρ in the above formula indicates the film density. ρ uses a value obtained by the density gradient tube method of D method of JIS K7112 (1980). At this time, ethanol and water are used as the density gradient tube liquid.

The thickness of the porous substrate can be appropriately determined depending on the thickness of the target composite polymer electrolyte membrane, but is preferably 1 to 100 μm in practice. When the film thickness is less than 1 μm, the film may be stretched due to the tension in the film forming process and the secondary processing process, and vertical wrinkles may be generated or broken. On the other hand, if it exceeds 100 μm, the polymer electrolyte is insufficiently filled and the proton conductivity is lowered.

In the composite polymer electrolyte membrane of the present invention, the porous substrate is impregnated with the mixed solution of the aromatic polymer electrolyte and the radical polymerizable compound, and after the solvent is removed, the crosslinking is advanced by irradiation with active energy rays. Can be obtained.

A method for producing the composite polymer electrolyte membrane will be described below. The method for impregnating the porous membrane with the mixed solution of the aromatic polymer electrolyte and the radical polymerizable compound is not particularly limited, and it is sufficient that the porous substrate and the mixed solution are in contact with each other. A step of removing the solvent after immersing the porous substrate in the pooled solution tank, a step of casting and impregnating the solution onto the porous substrate, and casting and applying the solution onto the substrate. And a step of impregnating and impregnating the porous substrate.

The mixing ratio of the aromatic polymer electrolyte and the radical polymerizable compound in the present invention is not particularly limited as long as it does not deviate from the above IEC range, but the aromatic polymer electrolyte / radical polymerizable compound (mass% ratio). Is preferably in the range of 90/10 to 40/60, and particularly preferably 75/25 to 40/60 in terms of proton conductivity, durability, and reactivity.

The concentration of the mixed solution of the aromatic polymer electrolyte and the radical polymerizable compound in the present invention is not particularly limited as long as it has fluidity, but is 1% by mass to 30% by mass, preferably 3 mass% to 15 mass%.

Examples of the solvent in the mixed solution include alcohols such as methanol, ethanol and isopropyl alcohol, aprotic organic solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone and dimethylsulfoxide, and water. Each of these solvents may be mixed. From the viewpoint of drying speed and film-forming property, it is preferable to use a mixed solvent of an alcohol solvent and water, and it is more preferable to use a mixed solvent of methanol and water.

After impregnating the porous membrane with the mixed solution of the aromatic polymer electrolyte and the radical polymerizable compound, the resulting composite membrane is irradiated with active energy rays to generate radicals and proceed with crosslinking. A polymer electrolyte membrane can be obtained.

In addition, heat treatment can be performed in parallel with or after these treatments. It is sufficient that a part of the aromatic polymer electrolyte and the radical polymerizable compound can be reacted, and the specific heating conditions are not particularly limited, but the treatment is performed at a temperature of 50 ° C. to 150 ° C. in terms of reactivity. Is preferable, and it is more preferable to process at 80-150 degreeC.

The ion exchange capacity (IEC) of the composite polymer electrolyte membrane of the present invention may be 1.5 meq / g or more from the viewpoint of proton conductivity of the composite polymer electrolyte membrane. It is preferably from 0.5 meq / g to 6.0 meq / g, and more preferably from 2.0 meq / g to 4.0 meq / g. When the IEC is lower than 1.5 meq / g, the proton conductivity is insufficient, and when the IEC is higher than 6.0 meq / g, there is a problem in the morphological stability of the membrane.

The composite polymer electrolyte membrane of the present invention can be used as an ion exchange membrane. Moreover, it can be used as a fuel cell or an electrolytic membrane by combining an electrode catalyst layer into a membrane / electrode assembly. The electrode catalyst layer includes a catalyst and an electrode material, and a known material can be used. For example, a conductive porous material such as carbon paper or carbon cloth can be used as the diffusion layer, but is not limited thereto. As the conductive porous material such as carbon paper or carbon cloth, a material subjected to surface treatment such as water repellent treatment or hydrophilic treatment can be used. A known material can be used for the catalyst. For example, platinum, an alloy of platinum and ruthenium, an alloy of platinum and cobalt, a core-shell catalyst having platinum as a core with a non-platinum metal such as palladium, a carbon alloy catalyst containing N, etc. It is not limited. As the binder of the electrode catalyst layer including the catalyst and particles carrying the catalyst, a resin having proton conductivity can be used, and a fluorine-based polymer electrolyte or a dispersion thereof can be used. In addition, a fluororesin for improving water repellency can be added, and a hydrophilic resin can be added for improving water retention.

The membrane / electrode assembly can be performed using a conventionally known method. For example, a method of applying an adhesive to the electrode surface and bonding the polymer electrolyte membrane and the electrode catalyst layer, or a polymer electrolyte membrane And a method of heating and pressurizing the electrode catalyst layer, a method of applying or spraying a dispersion of a catalyst and a binder on an electrolyte membrane, and drying. As the adhesive, a known one such as a Nafion (trade name) solution may be used, or an adhesive based on an ionic group-containing polymer constituting the composite polymer electrolyte membrane of the present invention may be used. You may use what has other hydrocarbon type proton conductive polymers as a main component.

The composite polymer electrolyte membrane of the present invention is made into a polymer electrolyte membrane / electrode assembly and then sandwiched between separators having oxygen and fuel flow paths to form a single cell of a fuel cell. A battery stack can be obtained.

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

<Polymer electrolyte membrane evaluation method>
The evaluation method of a polymer electrolyte membrane is shown below. In the evaluation, unless otherwise specified, the purpose is to accurately measure the thickness and mass, and the room temperature is 20 ° C. and the relative humidity is 40 ± 5 RH.
Evaluation was carried out in a measurement room controlled at%. In the measurement, 24 samples
What was left still in the measurement room for more than time was used.

<Thickness of polymer electrolyte membrane>
The thickness of the composite polymer electrolyte membrane was determined by measurement using a micrometer (Mitutoyo, standard micrometer). Measurement was performed at 10 locations, and the average value was taken as the thickness.

<Ion exchange capacity>
100 mg of the dried proton exchange membrane was immersed in 50 ml of 0.01 M NaOH aqueous solution and stirred at 25 ° C. for 2 hours. Thereafter, neutralization titration with 0.02 M aqueous HCl was performed. For neutralization titration, a potentiometric titrator COMMITE-980 manufactured by Hiranuma Sangyo Co., Ltd. was used. The ion exchange equivalent was calculated by the following formula.
Ion exchange capacity [meq / g] = (10-titer [mL]) / 2

<Proton conductivity>
A platinum wire (diameter: 0.2 mm) was pressed against the surface of the strip-shaped membrane sample on a self-made measuring probe (manufactured by Teflon (registered trademark)), and a constant temperature / humidity oven (Nagano Co., Ltd.) at 80 ° C. and 50% RH. The sample is held in Science Machine Mfg. Co., Ltd., LH-20-01), and the impedance between the platinum wires is set to SOLARTRON 1250 FREQUENCY RESPONSE ANALYSE.
Measured by R. Proton conductivity (σ) with the contact resistance between the membrane and the platinum wire canceled by the following formula from the slope of the measured resistance value estimated from the distance between the poles and the C-C plot. Was calculated.
σ [S / cm] = 1 / film width [cm] × film thickness [cm] × resistance interelectrode gradient [Ω / cm]

<Membrane weight reduction rate by Fenton test>
To a 1 L volumetric flask, 15 mg of iron (II) sulfate heptahydrate was added and ultrapure water was added. Subsequently, 100 ml of 30% aqueous hydrogen peroxide was taken using a 50 ml hole pipette and added to the volumetric flask. Finally, ultrapure water was added to the mark of the 1 L volumetric flask to prepare a Fenton reagent (Fe ²⁺ , 3 ppm, 3% H ₂ O ₂ ). Subsequently, a 2.5 × 5 cm piece of the composite membrane was cut out, immersed in 50 ml of Fenton solution, and kept at 80 ° C. for 3 hours. After the heat treatment, the composite membrane was lifted from the Fenton solution and dried overnight in a dry box, and the membrane weight of the composite membrane after drying was measured. The film weight reduction rate was evaluated by (film weight reduction before and after the Fenton test) / (composite film weight before the Fenton test).

<Bonding of polymer electrolyte membrane and electrode and power generation test>
[Catalyst transfer sheet] Obtained from DNP. Catalyst: TEC10E50E (Tanaka Kikinzoku Kogyo)
Electrolyte binder: NAFION DISPERSION Type: DE520 (manufactured by DuPont)
Base material: PET
Amount supported: Pt 0.40-0.45 mg / cm ²
[Production of membrane-electrode assembly]
5 x 5 cm composite polymer electrolyte membrane and 3 x 3 cm catalyst transfer film (DNP) were conditioned for 2 hours or more at 23 ° C and 50% RH, then in the same environment, "electrolyte membrane / catalyst transfer sheet / gas diffusion" The layers (made by SGL Carbon; SGL24-BCH) / Teflon (registered trademark) sheet / SUS plate ”were sandwiched in this order, and hot pressing was performed at 100 ° C., 14 kN / 9 cm ² for 5 minutes. After cooling, the base material of the catalyst transfer film was peeled off. The produced membrane-electrode assembly is incorporated into an evaluation fuel cell FC25-02SP manufactured by Electrochem, and hydrogen and oxygen are supplied at a cell temperature of 80 ° C. under conditions of an anode 47% RH and a cathode 47% RH. Characteristics were evaluated. The voltage at 0.3 A / cm ² after performance stabilization was compared.

Synthesis example 1
Poly [(p-phenylenesulfonic acid) -2,5-benzophenone]

Weigh anhydrous nickel chloride (97 mg, 0.75 mmol), triphenylphosphine (780 mg, 3.0 mmol), sodium iodide (56 mg, 0.37 mmol), zinc powder (980 mg, 15 mmol) into a 30 ml reaction vessel <A>. 3 ml of tetrahydrofuran was added. The temperature was raised to 70 ° C. and stirred for 10 minutes. In a different 30 ml reaction vessel <B>, 2,2-dimethylpropyl sulfonate 2,2-dimethylpropyl (1.9 g, 6.3 mmol), 2,5-dichlorobenzophenone (0.28 g, 1.12 mmol) and tetrahydrofuran (0.28 g, 1.12 mmol) were added. 7 ml) was added. The solution in the reaction vessel <B> was transferred to the reaction vessel <A> and stirred at 70 ° C. for 6 hours. The reaction solution was poured into 100 ml of 10% aqueous hydrochloric acid and filtered. Next, 1.3 g of the desired poly [(p-phenylenesulfonic acid) -2,2-dimethylpropyl-2,5-benzophenone] was synthesized by dispersing in 100 ml of acetone, dissolving the reaction mixture, and filtering. We were able to. Mn = 5300.
The synthesized polymer (1 g, corresponding to 4.4 mmol of sulfonic acid ester unit), trimethylamine hydrochloride (2.1 g, 22 mmol) and 20 ml of NMP were weighed in a 30 ml reaction vessel and stirred at 120 ° C. for 12 hours. The reaction mixture was washed with 100 ml of chloroform and washed with chloroform until the reaction residue of trimethylamine hydrochloride could be removed. A purified polymer, 10 g of a cation exchange resin (Dowex Monosphere 650C), and 10 g of pure water were weighed into a 100 ml Erlenmeyer flask and stirred at room temperature for 12 hours. The cation exchange resin was removed by filtration, the aqueous polymer solution was concentrated and dried, and 0.7 g of the desired product could be synthesized. The ion exchange capacity of the synthesized poly [(p-phenylene sulfonic acid) -2,5-benzophenone] was 5.5 meq / g.

Example 1
100 mg of poly [(p-phenylenesulfonic acid) -2,5-benzophenone] obtained in Synthesis Example 1, 65 mg of vinylsulfonic acid, 5 mg of vinylphosphonic acid, and 15 mg of triallyl isocyanurate were mixed with methanol / water [90/10 (w / W)] was dissolved in 4.3 g of the mixed solution. Thereafter, a polyethylene porous membrane (size: 10.5 × 10.5 cm, film thickness: 9 μm, porosity: 35%) immersed in methanol is placed on a PTFE substrate, and the above polymer solution is coated thereon. And dried at room temperature under a nitrogen atmosphere. The composite polymer electrolyte membrane after drying is fixed to a plastic frame, and an electron beam irradiation device (owned by NHV Corporation, EBC300 Curetron) is used to generate electrons at an acceleration voltage of 250 kV and an electron beam irradiation dose of 500 kGy. Line cross-linking was performed. After irradiation with the electron beam, the composite polymer electrolyte membrane was removed from the frame, immersed in 500 ml of ultrapure water and kept in a dryer at 80 ° C. for 24 hours to elute and remove components with insufficient crosslinking.
The obtained composite membrane had an ion exchange capacity of 2.54 meq / g, proton conductivity of 0.034 S / cm, and a membrane weight reduction rate after the Fenton test of 19%. The voltage at 0.3 A / cm ² during the power generation test was 0.87V.

Example 2
100 mg of poly [(p-phenylenesulfonic acid) -2,5-benzophenone] obtained in Synthesis Example 1, 50 mg of vinylsulfonic acid, 20 mg of vinylphosphonic acid, and 15 mg of triallyl isocyanurate were mixed with methanol / water [90/10 (w / W)] was dissolved in 4.3 g of the mixed solution. Thereafter, a polyethylene porous membrane (size: 10 × 10 cm, film thickness: 9 μm, porosity: 35%) immersed in methanol was placed on a PTFE substrate, and the polymer solution was coated thereon, and a nitrogen atmosphere Dry at room temperature. The composite polymer electrolyte membrane after drying is fixed to a plastic frame, and an electron beam irradiation device (owned by NHV Corporation, EBC300 Curetron) is used to generate electrons at an acceleration voltage of 250 kV and an electron beam irradiation dose of 500 kGy. Line cross-linking was performed. After irradiation with the electron beam, the composite polymer electrolyte membrane was removed from the frame, immersed in 500 ml of ultrapure water and kept in a dryer at 80 ° C. for 24 hours to elute and remove components with insufficient crosslinking.
The obtained composite membrane had an ion exchange capacity of 2.51 meq / g, proton conductivity of 0.018 S / cm, and a membrane weight reduction rate after the Fenton test of 3%. The voltage at 0.3 A / cm ² during the power generation test was 0.87V.

Example 3
100 mg of the poly [(p-phenylenesulfonic acid) -2,5-benzophenone] obtained in Synthesis Example 1, 35 mg of vinylsulfonic acid, 35 mg of vinylphosphonic acid, and 15 mg of triallyl isocyanurate were mixed with methanol / water [90/10 (w / W)] was dissolved in 4.3 g of the mixed solution. Thereafter, a polyethylene porous membrane (size: 10.5 × 10.5 cm, film thickness: 9 μm, porosity: 35%) immersed in methanol is placed on a PTFE substrate, and the above polymer solution is coated thereon. And dried at room temperature under a nitrogen atmosphere. The composite polymer electrolyte membrane after drying is fixed to a plastic frame, and an electron beam irradiation device (owned by NHV Corporation, EBC300 Curetron) is used to generate electrons at an acceleration voltage of 250 kV and an electron beam irradiation dose of 500 kGy. Line cross-linking was performed. After irradiation with the electron beam, the composite polymer electrolyte membrane was removed from the frame, immersed in 500 ml of ultrapure water and kept in a dryer at 80 ° C. for 24 hours to elute and remove components with insufficient crosslinking.
The obtained composite membrane had an ion exchange capacity of 2.80 meq / g, proton conductivity of 0.008 S / cm, and a membrane weight reduction rate after the Fenton test of 0%. The voltage at 0.3 A / cm ² during the power generation test was 0.83 V.

Comparative Example 1
100 mg of the poly [(p-phenylenesulfonic acid) -2,5-benzophenone] obtained in Synthesis Example 1, 20 mg of vinylsulfonic acid, 50 mg of vinylphosphonic acid, and 15 mg of triallyl isocyanurate were mixed with methanol / water [90/10 (w / W)] was dissolved in 4.3 g of the mixed solution. Thereafter, a polyethylene porous membrane (size: 10.5 × 10.5 cm, film thickness: 9 μm, porosity: 35%) immersed in methanol is placed on a PTFE substrate, and the above polymer solution is coated thereon. And dried at room temperature under a nitrogen atmosphere. The composite polymer electrolyte membrane after drying is fixed to a plastic frame, and an electron beam irradiation device (owned by NHV Corporation, EBC300 Curetron) is used to generate electrons at an acceleration voltage of 250 kV and an electron beam irradiation dose of 500 kGy. Line cross-linking was performed. After irradiation with the electron beam, the composite polymer electrolyte membrane was removed from the frame, immersed in 500 ml of ultrapure water and kept in a dryer at 80 ° C. for 24 hours to elute and remove components with insufficient crosslinking.
The obtained composite membrane had an ion exchange capacity of 3.06 meq / g, proton conductivity of 0.004 S / cm, and a membrane weight reduction rate after the Fenton test of 0%.

Comparative Example 2
100 mg of [(p-phenylene sulfonic acid) -2,5-benzophenone] obtained in Synthesis Example 1, 70 mg of vinylphosphonic acid, and 15 mg of triallyl isocyanurate are mixed in methanol / water [90/10 (w / w)]. Dissolved in 4.3 g. Thereafter, a polyethylene porous membrane size immersed in methanol: 10.5 × 10.5 cm, film thickness: 9 μm, porosity: 35%) was placed on a PTFE substrate, and the polymer solution was coated thereon. And dried at room temperature under a nitrogen atmosphere. The composite polymer electrolyte membrane after drying is fixed to a plastic frame, and an electron beam irradiation device (owned by NHV Corporation, EBC300 Curetron) is used to generate electrons at an acceleration voltage of 250 kV and an electron beam irradiation dose of 500 kGy. Line cross-linking was performed. After irradiation with the electron beam, the composite polymer electrolyte membrane was removed from the frame, immersed in 500 ml of ultrapure water and kept in a dryer at 80 ° C. for 24 hours to elute and remove components with insufficient crosslinking.
The obtained composite membrane had an ion exchange capacity of 2.53 meq / g, and proton conductivity could not be measured because of high membrane resistance. The film weight reduction rate after the Fenton test was 0%.

Comparative Example 3
100 mg of [(p-phenylene sulfonic acid) -2,5-benzophenone] obtained in Synthesis Example 1, 70 mg of vinyl sulfonic acid, and 15 mg of triallyl isocyanurate are mixed in methanol / water [90/10 (w / w)]. Dissolved in 4.3 g. Thereafter, a polyethylene porous membrane size immersed in methanol: 10.5 × 10.5 cm, film thickness: 9 μm, porosity: 35%) was placed on a PTFE substrate, and the polymer solution was coated thereon. And dried at room temperature under a nitrogen atmosphere. The composite polymer electrolyte membrane after drying is fixed to a plastic frame, and an electron beam irradiation device (owned by NHV Corporation, EBC300 Curetron) is used to generate electrons at an acceleration voltage of 250 kV and an electron beam irradiation dose of 500 kGy. Line cross-linking was performed. After irradiation with the electron beam, the composite polymer electrolyte membrane was removed from the frame, immersed in 500 ml of ultrapure water and kept in a dryer at 80 ° C. for 24 hours to elute and remove components with insufficient crosslinking.
The obtained composite membrane had an ion exchange capacity of 2.59 meq / g, proton conductivity of 0.041 S / cm, and a membrane weight reduction rate after the Fenton test of 34%. The voltage at 0.3 A / cm ² during the power generation test was 0.86V.

  From Table 1, the composite polymer electrolyte membrane of the present invention can suppress the decrease in membrane weight by increasing the amount of phosphorus atoms in the membrane in the Fenton test, and can find the conditions under which the power generation performance does not deteriorate in the power generation test. Expectation for application as a fuel cell membrane.

The composite polymer electrolyte membrane of the present invention can improve durability in the presence of peroxide radicals, and can be expected to greatly improve the practicality of hydrogen-fueled fuel cells. It contributes greatly to development.

Claims (9)

A radical polymerizable compound having a repeating structure represented by the following chemical formula 1 and the following chemical formula 2 and further having a sulfonic acid, a radical polymerizable compound having a phosphonic acid, and a bifunctional or higher functional radical polymerizable compound A composite polymer electrolyte membrane obtained by filling a porous substrate with a resin composition containing at least one selected, and then polymerizing by irradiation with active energy rays, wherein the polymer electrolyte contains 0.1 to 7 phosphorus atoms. A composite polymer electrolyte membrane comprising 0% by mass.

Wherein R ¹ and R ² are any one of hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms, and R ¹ and R ² may be the same or different. R ³ represents either an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms which may have a substituent, and when R ³ has a substituent, the substituent is hydrogen. , Any one of an alkyl group having 1 to 20 carbon atoms and an aryl group having 6 to 20 carbon atoms, and when having a plurality of the substituents, the substituents may be the same or different. b represents an integer of 1 to 4. p and q are 0 or 1 satisfying p + q = 1.)

(In the formula, m and n are positive integers and m + n = 5 to 1000. R ⁴ is any one of hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. ^{May be the same} or different, r is 1 or 2, d is 4-r, A is OR ⁵ or N (R ⁶ ) (R ⁷ ), R ⁵ is hydrogen, An alkali metal, an alkyl group having 1 to 20 carbon atoms, R ⁶ and R ⁷ are either hydrogen or an alkyl group having 1 to 20 carbon atoms, and R ⁶ and R ⁷ may be the same May be different.)   The composite polymer electrolyte membrane according to claim 1, wherein the polymer electrolyte contains 0.5 to 7.0 mass% of phosphorus atoms. The composite polymer electrolyte membrane according to claim 1, wherein the radical polymerizable compound having phosphonic acid is a compound represented by the following chemical formula 3.

(In the formula, R ⁸ is hydrogen or an alkyl group having 1 to 20 carbon atoms. R ⁹ is a direct bond, an alkyl group having 1 to 20 carbon atoms, or a phenyl group. And B represents OR ¹⁰ or N (R ¹¹ ) (R ¹² ), R ¹⁰ represents any one of hydrogen, an alkali metal, and an alkyl group having 1 to 20 carbon atoms, and R ¹¹ and R ¹² is either hydrogen or an alkyl group having 1 to 20 carbon atoms, and R ¹¹ and R ¹² may be the same or different. ) The composite polymer electrolyte membrane according to claim 1, wherein the radically polymerizable compound having phosphonic acid is vinylphosphonic acid. The composite polymer electrolyte membrane according to any one of claims 1 to 4, wherein the active energy ray is an electron beam or an ultraviolet ray.   The composite polymer electrolyte membrane according to any one of claims 1 to 5, wherein the material of the porous substrate is a polymer material.   The composite polymer electrolyte membrane according to any one of claims 1 to 6, wherein the polymer electrolyte membrane has an ion exchange capacity of 1.5 meq / g to 6.0 meq / g.   The polymer electrolyte membrane electrode assembly for fuel cells using the composite polymer electrolyte membrane in any one of Claims 1-7.   A fuel cell using the polymer electrolyte membrane electrode assembly according to claim 8.