JP4687077B2 - Proton conductive polymer composition and method for producing the same - Google Patents

Description

  The present invention relates to a proton conductive polymer composition and a method for producing the same, and more particularly to a proton conductive polymer composition useful as an electrolyte membrane of a solid polymer electrolyte fuel cell and a method for producing the same. Is.

Conventionally, as a proton conductive electrolyte membrane, a fluorine-based ion exchange resin membrane (for example, see Patent Document 1) typified by a perfluorosulfonic acid resin (for example, a product name Nafion membrane manufactured by DuPont) is used. It has a proton exchange group in the molecule, exhibits proton conductivity of about 0.1 (S / cm) at 80 ° C. and 100% RH, and functions as a proton conductive electrolyte.
JP 2000-119420 A

However, ion exchange resin membranes made of conventional perfluorosulfonic acid resin-based materials have a problem that the maximum operating temperature is as low as about 80 ° C., and the manufacturing process is complicated and very expensive.
The first object of the present invention is to exhibit proton conductivity equivalent to or higher than that of an ion exchange resin membrane made of a conventional perfluorosulfonic acid resin material, and has a high maximum operating temperature of about 80 to 120 ° C., which is inexpensive. Providing a high performance proton conducting polymer composition;
The second object of the present invention is to provide a method for producing such an inexpensive and high-performance proton conducting polymer composition by a simple production process.

The proton-conductive polymer composition according to claim 1 of the present invention for solving the above-described problem is a benzenesulfonic acid, naphthalenesulfonic acid, or a plurality of sulfonic acid groups that do not contain a polymerizable functional group in the molecule. look contains a resin having no functional group and chelate groups reactive with organic acid and a sulfonic acid group having at least is one sulfonic group selected from an organic acid having, and no organic amine A proton conducting polymer composition comprising:
The organic acid having a sulfonic acid group is uniformly dispersed in the resin and is formed into a film shape in a state of being chemically bonded to the resin.

(Delete)

Proton-conducting polymer composition according to claim 2 Symbol mounting of the present invention is the proton-conducting polymer composition according to claim 1 Symbol placement, which is characterized in that said resin is a polyether sulfone (PES) It is.

A third aspect of the present invention is the method for producing a proton conductive polymer composition according to the first or second aspect, comprising the following steps (1) to (4).
(1) an organic acid having at least one sulfonic acid group selected from benzenesulfonic acid, naphthalenesulfonic acid, or an organic acid having a plurality of sulfonic acid groups, which does not contain a polymerizable functional group in the molecule ; A resin that does not have a functional group that reacts with a sulfonic acid group and a chelating functional group is dissolved in a common solvent, and then both are mixed to form a liquid polymer composition.
(2) The viscosity of the polymer liquid composition is adjusted by volatilizing the solvent.
(3) The viscosity of the polymer liquid composition is applied on a substrate to form a film and dried. (4) After drying, the resin is irradiated with an electron beam to chemically bond the resin and the organic acid.

Claim 4 of the present invention is the manufacturing method according to claim 3 Symbol placement, is characterized in that said solvent is N- methyl-1-pyrrolidone (NMP).

The proton conductive polymer composition according to claim 1 of the present invention is at least selected from benzenesulfonic acid, naphthalenesulfonic acid, or an organic acid having a plurality of sulfonic acid groups, which does not contain a polymerizable functional group in the molecule. look contains a resin having no functional group and chelate groups reactive with organic acid and a sulfonic acid group with is one sulfonic acid group, and the proton-conducting polymer composition containing no organic amine Because
The organic acid having the sulfonic acid group is uniformly dispersed in the resin and is formed into a film shape in a state of being chemically bonded to the resin,
The proton conductivity is equivalent to or better than that of conventional ion-exchange resin membranes made of perfluorosulfonic acid resin materials, and the maximum operating temperature is as high as about 80-120 ° C. It is inexpensive, durable, and highly reliable. There is a remarkable effect of high performance.
When the organic acid is at least one selected from benzenesulfonic acid, naphthalenesulfonic acid, or an organic acid having a plurality of sulfonic acid groups, a high-performance proton conductive polymer composition can be easily obtained using these organic acids. In addition to being able to obtain a product, it is easy to handle, inexpensive, and easily available.

(Delete)

Proton-conducting polymer composition according to claim 2 of the present invention is the proton-conducting polymer composition according to claim 1 Symbol mounting, characterized in that said resin is a polyether sulfone (PES) Yes,
In addition to obtaining a high-performance proton conductive polymer composition that is superior in heat resistance, it is possible to obtain a further remarkable effect that it is easy to handle and obtain.

A third aspect of the present invention is the method for producing a proton conductive polymer composition according to the first or second aspect, comprising the steps (1) to (4), for example, intramolecularly. The organic acid having no polymerizable functional group and the sulfonic acid group- containing organic acid and the resin are dissolved in a common solvent, and then mixed together to form a liquid polymer composition. The solvent in the liquid composition is volatilized and applied to the substrate to adjust the viscosity to be easily formed into a film, and the polymer liquid composition is applied to the substrate to form a film. Then, after drying, the low-cost and high-performance proton-conductive polymer composition of the present invention is easily manufactured by a simple manufacturing process in which the resin and the organic acid are chemically bonded by irradiation with an electron beam. There is a remarkable effect of being able to.

Claim 4 of the present invention is the manufacturing method according to claim 3 Symbol mounting, and characterized in that said solvent is N- methyl-1-pyrrolidone (NMP),
NMP has an even more remarkable effect that both the organic acid having a sulfonic acid group and the resin are easily dissolved, and easy to handle and obtain.

Next, the method for producing the proton conductive polymer composition of the present invention will be described in detail.
In step (1), an organic acid having a sulfonic acid group which is at least one selected from benzenesulfonic acid, naphthalenesulfonic acid, or an organic acid having a plurality of sulfonic acid groups, which does not contain a polymerizable functional group in the molecule The resin having no functional group that reacts with the sulfonic acid group and no chelating functional group is dissolved in a common solvent. That is, when there is a solvent capable of separately dissolving the organic acid and the resin using the same solvent, the proton conductive polymer composition of the present invention can be produced by the production method of the present invention. The organic acid and the resin are sufficiently dissolved separately and then mixed to form a liquid polymer composition. The concentration, temperature, time, apparatus, etc. of dissolution differ depending on the type and combination of the organic acid and the resin.

  In the step (2), the uniformly polymerized liquid polymer composition is vacuum-dried at a temperature at which the organic acid does not volatilize and dissipate using, for example, a vacuum dryer, for example, at a temperature of 80 ° C. or less, and the polymer liquid When the solvent in the composition is volatilized, the solvent is concentrated to increase the viscosity. Therefore, it can be adjusted to a viscosity suitable for forming a film by applying it on a substrate. When such a viscosity is reached, the volatilization of the solvent is stopped. The optimum viscosity varies depending on the method of forming a film by applying on the substrate, but the viscosity is adjusted to an appropriate viscosity by the above method.

  In the step (3), the polymer liquid composition whose viscosity is adjusted is applied on a substrate to form a film. Then, the film-like film | membrane or sheet-like film | membrane of a dried state can be obtained by removing the said solvent in a film | membrane by oven drying or vacuum drying. The degree of vacuum, temperature, time, etc. vary depending on the solvent used. When the solvent is NMP, for example, drying is performed while exhausting at 80 to 120 ° C. for 1 to 10 hours. However, in this state, the organic acid and the trace amount of the solvent remaining in the resin matrix are not chemically bonded to the resin. For example, if left to stand, the trace amount of the organic acid or the solvent is removed from the resin. Leaching.

  Therefore, in the step (4), the sulfonic acid group is irradiated by irradiating an electron beam having an energy of, for example, several hundred to several thousand electron volts to the dried film-like or sheet-like membrane obtained in the step (3). The proton-conducting polymer composition of the present invention is obtained in which the organic acid having a hydrogen atom is uniformly dispersed in the resin and formed into a film in a state where the organic acid is chemically bonded to sites other than the resin and the sulfonic acid group. be able to. The obtained proton-conductive polymer composition of the present invention is stable and excellent in durability without being leached out of the resin even when left as it is or immersed in water. The maximum operating temperature can be as high as about 80 to 120 ° C., depending on the type and combination of the organic acid and the resin.

The resin used in the present invention may be a thermoplastic resin, a thermosetting resin, or a mixture of two or more thereof. For example, engineering plastics, engineering plastics, etc. that have high heat resistance, mechanical properties, and high chemical stability. Those selected from can be preferably used.
Specifically, polyetheretherketone (PEEK), liquid crystal polymer (LCP), fluororesin, polyethernitrile (PEN), polysulfone (PSF), polyethersulfone (PES), polyarylate (PAR), polyamideimide (PAI), polyetherimide (PEI), thermoplastic polyimide (PI), polycarbonate (PC), modified polyphenylene ether (mPPE), polyamide (PA), polyacetal (POM), polybutylene terephthalate (PBT), polyethylene terephthalate ( PET) and syndiotactic polystyrene (SPS).

  Specific examples of the organic acid having a sulfonic acid group used in the present invention include, for example, benzenesulfonic acid, dodecylbenzenesulfonic acid, 2-naphthalenesulfonic acid, 1,5-naphthalenedisulfonic acid, and 2,6-naphthalenedisulfonic acid. 1,3,6-naphthalene trisulfonic acid, 1,3,5,7-naphthalene tetrasulfonic acid, or a mixture of two or more thereof.

  Although the compounding quantity of the organic acid which has a sulfonic acid group used by this invention is based on the kind, it is 10-90 mass% with respect to the said resin. If it is less than 10% by mass, the proton conductivity may be inferior, and if it exceeds 90% by mass, the heat resistance and mechanical properties may be impaired.

  The solvent used in the present invention is not particularly limited as long as it is a solvent that can well dissolve the organic acid and the resin used in the present invention. Specific examples include NMP. NMP can be preferably used in the present invention because it easily dissolves both the organic acid and the resin.

  The substrate used in the present invention can be formed into a film by applying the liquid polymer composition used in the present invention or the like, and can be organic or inorganic as long as it can withstand drying and electron beam irradiation. It may be a natural product, a synthetic product, or a mixture of two or more thereof, and is not particularly limited in shape, form, size, surface condition, and the like. As a specific example, for example, a plate made of SUS316 (the surface finish may be a mirror finish or a rough finish) may be mentioned.

EXAMPLES Next, although an Example demonstrates this invention in detail, unless it deviates from the main point of this invention, it is not limited to these Examples.
Example 1
A solution in which PES (polyether sulfone, trade name: Sumika Excel, manufactured by Sumitomo Chemical Co., Ltd.) is dissolved in NMP so as to be 5% by mass at normal temperature is prepared. On the other hand, a solution in which naphthalenesulfonic acid is dissolved in NMP so as to be 5% by mass at room temperature is prepared. Then, an equal amount of both solutions were mixed and stirred to prepare a liquid polymer composition (the mass ratio of PES dissolved in the liquid polymer composition to naphthalenesulfonic acid is 1: 1).

  The viscosity of the liquid polymer composition thus prepared was not very different from that of NMP, and thus is not suitable for application by a bar coater or the like. Therefore, it was dried in a vacuum dryer at 40 ° C. for 10 hours, and NMP was removed to some extent to obtain a liquid polymer composition having a viscosity of about 5000 mPa · s.

  This liquid polymer composition was applied to the surface of an aluminum foil, which is a hydrophilic substrate, with a bar coater. Then, it was dried in an oven at 150 ° C. for 10 hours to obtain a film having a thickness of about 50 μm.

  This film was irradiated with an electron beam at 50 Mrad in an electron beam irradiation device (Iwasaki Electric Co., Ltd., model LB4008) in normal temperature and air. When the obtained film was heated to about 130 ° C., naphthalene sulfonic acid or the like did not leach out of the PES resin, and even when immersed in water, naphthalene sulfonic acid or the like did not leach out of the PES resin.

(Measurement of proton conductivity)
FIG. 1 is a cross-sectional explanatory view of a membrane electrode assembly in which electrode catalyst layers are formed on both surfaces of the film.
The film 1 obtained by irradiating the electron beam with 50 Mrad is used as a proton conductive solid polymer electrolyte membrane, and electrode catalyst layers 2 and 3 are joined and laminated on both sides by a conventional method to form a membrane electrode assembly 12. Yes.

FIG. 2 is an exploded cross-sectional view showing the configuration of a single cell of a polymer electrolyte fuel cell equipped with the membrane electrode assembly 12. The air electrode side gas diffusion layer 4 having a structure in which a mixture of carbon black and polytetrafluoroethylene (PTFE) is applied to carbon paper, facing the electrode catalyst layer 2 and the electrode catalyst layer 3 of the membrane electrode assembly 12, and The fuel electrode side gas diffusion layer 5 is disposed. Thereby, the air electrode 6 and the fuel electrode 7 are comprised, respectively. A set of conductive and gas-impermeable materials having a gas flow path 8 for reaction gas flow facing a single cell and a cooling water flow path 9 for cooling water flow on the opposing main surface. A single cell 11 is formed by being sandwiched by the separator 10.
Then, under the measurement conditions of 40 ° C. and relative humidity of 100%, hydrogen gas is supplied to the fuel electrode 7 at 100 sccm (Standard Cubic Centimeter, 25 ° C., gas flow rate at 1 atm, cm ³ / sec) and air is supplied to the air electrode 6 at 300 sccm. DC power was generated by causing an electrochemical reaction. And the resistance value of the said film 1 was measured with the alternating current impedance method. As a result, the resistance value of the film 1 was 50 mΩ, the film thickness was 50 μm, and the electrode area was 5 cm ² , so the proton conductivity was 2 × 10 ⁻² S / cm.

(Example 2)
Organic-inorganic hybrid polymer with ladder structure instead of PES (Glass
Resin 950F (manufactured by Techne Glass, Inc., USA) is dissolved in NMP so as to be 5% by mass at room temperature. On the other hand, a solution in which naphthalenesulfonic acid is dissolved in NMP so as to be 5% by mass at room temperature is prepared. Then, an equal amount of both solutions were mixed and stirred to prepare a liquid polymer composition (the mass ratio of the organic / inorganic hybrid polymer dissolved in the liquid polymer composition to naphthalenesulfonic acid is 1: 1). ).

  The liquid polymer composition thus prepared was placed in a PTFE container and dried in air at 200 ° C. for 5 hours to obtain a sheet having a thickness of about 0.5 mm at the bottom of the PTFE container.

This sheet was irradiated with an electron beam by 50 Mrad in an electron beam irradiation device (Iwasaki Electric Co., Ltd., model LB4008) in normal temperature and air. The obtained sheet does not leach naphthalene sulfonic acid from the organic / inorganic hybrid polymer resin even when heated to about 130 ° C., and naphthalene sulfonic acid etc. from the organic / inorganic hybrid polymer resin even when immersed in water. There was no leaching.
The sheet obtained by irradiating the electron beam with 50 Mrad was moistened with water and measured for resistance using a resistance measuring device. As a result, an initial resistance value of about 1 MΩ was shown, and the resistance value gradually increased, and proton conduction It was found to have sex.

  The proton conductive polymer composition of the present invention exhibits a proton conductivity equivalent to or higher than that of a conventional ion exchange resin membrane made of a perfluorosulfonic acid resin material, and has a high maximum operating temperature of about 80 to 120 ° C. It has a high performance such as low cost, excellent durability and high reliability, and has a remarkable effect that it can be easily manufactured by the manufacturing method of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional explanatory view of a membrane electrode assembly in which electrode catalyst layers are formed on both surfaces of a proton conductive polymer composition film of the present invention. FIG. 2 is an exploded cross-sectional view showing the configuration of a single cell of a polymer electrolyte fuel cell equipped with the membrane electrode assembly shown in FIG.

DESCRIPTION OF SYMBOLS 1 Film 2 of proton-conductive polymer composition of this invention, 3 Electrode catalyst layer 4 Air electrode side gas diffusion layer 5 Fuel electrode side gas diffusion layer 6 Air electrode 7 Fuel electrode 8 Gas flow path 9 Cooling water flow path 10 Separator 11 Single cell 12 Membrane electrode assembly

Claims (4)

An organic acid having at least one sulfonic acid group selected from benzenesulfonic acid, naphthalenesulfonic acid, or an organic acid having a plurality of sulfonic acid groups, which does not contain a polymerizable functional group in the molecule ; look contains a resin having no functional group and chelate groups react, and a proton-conducting polymer composition free of organic amines,
A proton-conducting polymer composition, wherein the organic acid having a sulfonic acid group is uniformly dispersed in the resin and formed into a film in a state of being chemically bonded to the resin.   The proton conductive polymer composition according to claim 1, wherein the resin is polyethersulfone (PES). 3. The method for producing a proton conductive polymer composition according to claim 1 or 2, comprising the following steps (1) to (4).
(1) an organic acid having at least one sulfonic acid group selected from benzenesulfonic acid, naphthalenesulfonic acid, or an organic acid having a plurality of sulfonic acid groups, which does not contain a polymerizable functional group in the molecule ; A resin that does not have a functional group that reacts with a sulfonic acid group and a chelating functional group is dissolved in a common solvent, and then both are mixed to form a liquid polymer composition.
(2) The viscosity of the polymer liquid composition is adjusted by volatilizing the solvent.
(3) The viscosity of the polymer liquid composition is applied on a substrate to form a film and dried. (4) After drying, the resin is irradiated with an electron beam to chemically bond the resin and the organic acid.   The process according to claim 3, wherein the solvent is N-methyl-1-pyrrolidone (NMP).

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