JP2010108626A - Membrane electrode assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane electrode assembly having a high catalyst utilization ratio and excellent adhesiveness between a membrane and an electrode by using a hydrocarbon system binder as an electrode for the MEA in which a hydrocarbon system electrolyte membrane is used. <P>SOLUTION: In the membrane electrode assembly in which a hydrocarbon system electrolyte membrane is used, a hydrocarbon system binder is used for an electrode. The hydrocarbon system binder contains a structural unit as shown in a general formula (1), wherein A is alkylene group having carbon numbers 5 to 20 and B, C, D and E are hydrogen and fluorine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a membrane electrode assembly (hereinafter referred to as “MEA” (Mebrane Electrode Assembly)).

A fuel cell is expected as a next-generation power generation device that has high power generation efficiency and excellent environmental properties, and can contribute to solving environmental problems and energy problems that are currently a major issue.
Among these fuel cells, the polymer electrolyte fuel cell is smaller and has higher output than any other system, and is a small-sized on-site, mobile (on-vehicle), portable fuel cell. It is considered as the next generation mainstay.

  At present, solid polymer fuel cells have not yet reached the practical stage, but the polymer electrolyte membranes of fuel cells that are used in trial production or test stages have perfluoroalkylene groups as the main skeleton. As a fluorine-based polymer electrolyte membrane having an ion exchange group such as a sulfonic acid group or a carboxylic acid group at the end of the perfluorovinyl ether side chain, “Nafion (DuPont, product name)”, “Flemion (Asahi) “Glass Co., Ltd., trade name)” is known.

However, in the currently used fuel cell polymer electrolyte membrane “Nafion (DuPont, product name)” and the like, the moisture content of the polymer electrolyte membrane increases when it is operated at a temperature exceeding 100 ° C. In addition to the rapid decrease, the softening of the polymer electrolyte membrane has become remarkable, and in the direct methanol fuel cell, where the future is especially expected, fluorine like the conventional “Nafion (DuPont, product name)” When proton-based proton conductive polymer material is used as an electrolyte, methanol that has passed through the anode diffuses in the electrolyte and reaches the cathode, where it directly reacts with the oxidant (O ₂ ) on the cathode catalyst. This causes a short-circuit phenomenon (crossover) and significantly lowers the battery performance, so that there is a problem that sufficient performance cannot be exhibited.

In order to solve such problems, various studies have been made on polymer electrolyte membranes in which a sulfonic acid group for imparting proton conductivity is introduced to a heat-resistant aromatic polymer used as a substitute for a fluorine-based membrane. From the viewpoint of heat resistance and chemical stability of the polymer electrolyte membrane, sulfonated aromatic polyether ketones, sulfonated aromatic polyether sulfones, sulfonated polyphenylenes and the like have been reported (for example, (See Patent Documents 1 to 3).
However, when the hydrocarbon electrolyte membrane is made into MEA, “Nafion (trade name, manufactured by DuPont), which is usually used as a binder for electrodes, is a fluorine-based polymer. It is generally known that the adhesion is not good.
In order to solve this problem, a method has been studied in which an electrolyte polymer is coated on the electrolyte membrane to improve bondability (see Patent Document 4).
JP-A-6-93114 Japanese Patent No. 3861367 JP 2001-329053 A JP 2006-85955 A

  However, in the electrolyte membrane described in Patent Document 4, the swelling rate is increased due to an increase in the sulfonic acid group, the bonding property with the electrolyte membrane is lowered, and there is a problem in long-term durability. For this reason, studies have been made using a hydrocarbon-based resin as a binder, but there is a problem that the utilization rate of a catalyst which is a reaction site in an electrode is low (see Japanese Patent Application Laid-Open No. 2005-197071).

  In view of the above circumstances, the present invention uses a hydrocarbon-based binder as an electrode of an MEA (membrane electrode assembly) using a hydrocarbon-based electrolyte membrane, so that the catalyst utilization rate is high and the membrane / electrode bonding is performed. It aims at providing MEA with good property.

The present invention relates to the following.
(1) A membrane electrode assembly using a hydrocarbon electrolyte membrane.
(2) The membrane electrode assembly according to item (1), wherein the electrode uses a hydrocarbon binder.
(3) The membrane electrode assembly according to item (2), wherein the hydrocarbon binder includes a structural unit represented by the following general formula (1).

［式中Ａは炭素数５〜２０のアルキレン基を示す。Ｂ、Ｃ、Ｄ、Ｅは水素、フッ素を示す。］

[Wherein A represents an alkylene group having 5 to 20 carbon atoms. B, C, D, and E represent hydrogen and fluorine. ]

(4) In the item (2) or (3), the hydrocarbon binder contains a hydrophilic part containing any one or more of a sulfonic acid group, a phosphoric acid group, or a carboxyl group, a sulfonic acid group, a phosphoric acid group, or A membrane electrode assembly, which is a copolymer with a hydrophobic part not containing a carboxyl group.
(5) The membrane electrode assembly according to any one of items (2) to (4), wherein the copolymerization component of the hydrocarbon binder is the following general formula (2).

［式中Ａは炭素数５〜２０のアルキレン基を示す。ｘは、モル％である。］

[Wherein A represents an alkylene group having 5 to 20 carbon atoms. x is mol%. ]

(6) The membrane electrode assembly according to any one of items (1) to (5), wherein an electrode is formed on the hydrocarbon electrolyte membrane using a spray coating method, a GDE method, or a transfer method.
(7) The membrane electrode assembly according to any one of items (1) to (6), wherein a catalyst slurry containing a noble metal catalyst is spray-coated on a hydrocarbon electrolyte membrane, and an electrode is directly formed on the electrolyte membrane. .
(8) The membrane electrode assembly according to item (7), wherein the catalyst slurry contains a noble metal catalyst, an electrolyte binder, and a solvent, and the noble metal catalyst and the electrolyte binder are dissolved or dispersed in the solvent.

  The present invention uses a binder having a hydrocarbon-based material as an electrode of a membrane-electrode assembly using a hydrocarbon-based electrolyte membrane, so that the catalyst utilization rate and the membrane / electrode bondability are good. Provide the body.

Hereinafter, the present invention will be described in detail.
As a result of diligent research to achieve the above object, the use of the binder having the hydrocarbon-based material of the present invention for the electrode improves the catalyst utilization rate and provides good membrane / electrode bondability. I understood that.
The hydrocarbon binder of the present invention is present in the electrode. As the role of the binder, it promotes the bonding between the electrode and the electrolyte membrane and bears the adhesion between the electrode constituent materials (for example, catalyst-supporting carbon and gas diffusion layer). Further, it also has a function of proton transfer from the reaction site of the catalyst and plays a role of improving the reaction site.

<Hydrocarbon electrolyte membrane>
Examples of the main skeleton of the hydrocarbon electrolyte membrane include polyetheretherketone, polyphenylene, polyimide, polyether, polyethersulfone, and the like.
Examples of the proton conductive group of the hydrocarbon electrolyte membrane include a sulfonic acid group, a phosphoric acid group, and a carboxyl group. Among these, a sulfonic acid group is preferable in terms of the degree of acid dissociation, but other substituents may be used.
The amount of protonic acid groups in the hydrocarbon-based electrolyte membrane is not particularly limited, but from the viewpoint of proton conductivity and durability, the value of ion exchange equivalent mass (EW value) is preferably 300 to 1,000, and preferably 350 to 900. More preferred is 400 to 800.
Here, the ion exchange equivalent mass (EW value) refers to the weight (g) of the copolymer per mole of proton acid groups. If the EW value is 300 or more, the durability does not deteriorate. If the EW value is 1000 or less, the proton conductivity is good.

<Hydrocarbon binder>
The hydrocarbon binder used in the present invention is preferably a structural unit of the above general formula (1). Moreover, what is shown to the following chemical formula and 1-1-8 can also be used.

Examples of the main skeleton of the hydrocarbon binder include polyether ether ketone, polyphenylene, polyimide, polyether, polyether sulfone, and the like, but polyether sulfone is preferable from the viewpoint of gas permeability.
Examples of the proton conductive group of the hydrocarbon electrolyte membrane include a sulfonic acid group, a phosphoric acid group, and a carboxyl group. Among these, a sulfonic acid group is preferable in terms of the degree of acid dissociation, but other substituents may be used.

  The amount of protonic acid groups in the hydrocarbon binder is not particularly limited, but from the viewpoint of proton conductivity and durability, the value of ion exchange equivalent mass (EW value) is preferably 300 to 1000, more preferably 350 to 900. 400-800 are more preferable. Here, the ion exchange equivalent mass (EW value) refers to the weight (g) of the copolymer per mole of proton acid groups. If the EW value is 300 or more, the durability does not deteriorate, and if it is 1000 or less, the proton conductivity is good.

The solvent used for synthesizing the copolymer is not particularly limited as long as the monomer used is soluble, but specific reaction solvents include N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl. A suitable one can be selected from aprotic polar solvents such as sulfoxide, N-methyl-2-pyrrolidone, hexamethylphosphonamide, and γ-butyrolactone. A plurality of these solvents may be used as a mixture within a possible range.
The amount of solvent can be used in the range of 0.1 to 100 times the total mass of the monomer and catalyst to be reacted.
The reaction temperature of the copolymer is preferably 80 ° C. to 210 ° C., more preferably 90 ° C. to 200 ° C., further preferably 100 ° C. to 190 ° C. If 80 ° C. or higher, the copolymerization reaction will be insufficient. If it is 210 degrees C or less, there is no decomposition | disassembly of a copolymer.
The copolymer of the present invention can be used, for example, as necessary, for example, antioxidants, heat stabilizers, lubricants, tackifiers, plasticizers, crosslinking agents, viscosity modifiers, antistatic agents, antibacterial agents, antifoaming agents. Various additives such as an agent, a dispersant, and a polymerization inhibitor may be included.

<Catalyst layer>
As the catalyst material used in the catalyst layer, for example, platinum group metals such as platinum, rhodium, ruthenium, iridium, palladium, osnium, and alloys thereof are suitable. These catalyst materials and salts of the catalyst materials may be used alone or in combination. Among them, metal salts and complexes, particularly ammine complexes represented by [Pt (NH ₃ ) ₄ ] X ₂ or [Pt (NH ₃ ) ₆ ] X ₄ (X is a monovalent anion) are preferable.
Moreover, when using a metal compound as a catalyst, the mixture of several compounds may be used and double salt may be sufficient. For example, by using a mixture of a platinum compound and a ruthenium compound, formation of a platinum-ruthenium alloy can be expected by a reduction process.

  The particle size of the catalyst is not particularly limited, but it is preferable that the average particle size is 0.5 to 20 nm from the viewpoint of an appropriate size that increases the catalyst activity. K.K. In a study by Kinoshita et al. (J. Electrochem. Soc., 137, 845 (1990)), it is reported that the particle size of platinum having a high activity for oxygen reduction is about 3 nm.

  A cocatalyst can be further added to the catalyst used in the present invention. Examples of the cocatalyst include finely divided carbon. The finely divided carbon is preferably one in which the coexisting catalyst exhibits high activity. For example, when a platinum group metal compound is used as the catalyst, acetylene black such as Denka Black, Valcan XC-72, Black Pearl 2000, etc. Is appropriate.

The amount of the catalyst varies depending on the deposition method and the like, but it is appropriate that the catalyst is deposited on the surface of the gas diffusion layer in the range of 0.02 to 20 mg / cm ² , for example. Moreover, it is appropriate that it exists in the quantity of 0.01-10 mass% with respect to the total amount of an electrode, for example, Preferably, it is 0.3-5 mass%.

<Gas diffusion layer>
As the gas diffusion layer, for example, a known substrate having air permeability such as a carbon fiber woven fabric or carbon paper can be used. Preferably, those substrates and the like that have been subjected to water repellent treatment are used. The water repellent treatment is performed, for example, by immersing these substrates in an aqueous solution of a water repellent made of fluororesin such as polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, drying, and firing. Is done.

<Electrode>
The electrode includes a gas diffusion layer and a catalyst layer provided on and / or in the gas diffusion layer.
The resulting electrode is porous. The average pore diameter of the electrode is, for example, 0.01 to 50 μm, preferably 0.1 to 40 μm. Furthermore, the porosity of the electrode is, for example, 10 to 99%, preferably 10 to 60%.

<Membrane electrode assembly>
The membrane / electrode assembly of the present invention is produced by providing the electrode on an electrolyte membrane. Preferably, the catalyst layer side of the electrode is joined to the electrolyte membrane side. Examples of the method for producing the membrane electrode assembly include the following three methods.
(A) Spray coating method: a method in which a catalyst layer is directly formed on an electrolyte membrane to form a catalyst layer, and further a gas diffusion layer is formed on the formed catalyst layer. For example, according to the method described in JP 2000-516014 A, a catalyst material containing a perfluorocarbon polymer having an ion exchange group, a platinum group catalyst, finely divided carbon (carbon black) and other additives is applied on the electrolyte membrane. There is a method in which a catalyst layer is formed by spraying, printing or the like, and a gas diffusion layer is thermocompression-bonded on the catalyst layer by hot pressing or the like.
(B) GDE bonding: A method in which an electrode is prepared in advance by immersing the gas diffusion layer in a catalyst material solution, and the obtained electrode is provided on the electrolyte membrane. For example, the gas diffusion layer is immersed in a solution (paste) of a soluble platinum group salt to adsorb (ion exchange) the soluble platinum group salt on and in the gas diffusion layer. Next, there is a method in which a metal serving as a catalyst is deposited on the gas diffusion layer by dipping in a reducing agent solution such as hydrazine or Na ₂ BO ₄ .
(C) Transfer method: A method in which a catalyst layer is prepared in advance on a substrate to produce a catalyst layer, the obtained catalyst layer is transferred onto an electrolyte membrane, and a gas diffusion layer is formed on the formed catalyst layer. For example, polytetrafluoroethylene in advance and platinum black synthesized by the Thomas method, etc., are uniformly mixed, applied onto a fluororesin sheet substrate, press-molded, transferred onto the electrolyte membrane, and further gas diffusion There is a method in which layers are arranged and the obtained laminate is pressure-bonded.

  A more preferable method for producing a membrane / electrode assembly of the present invention includes a method in which an electrode material containing a catalyst substance and a gas diffusion layer material is directly applied on an electrolyte membrane. Specifically, catalyst-supported carbon particles or catalyst black supporting a catalyst material such as platinum-ruthenium (Pt-Ru) or platinum (Pt) is used as the catalyst material. A catalyst slurry is made by mixing with a binder such as an electrolyte and optionally a water repellent such as polytetrafluoroethylene (PTFE) particles used in the manufacture of the gas diffusion layer. The catalyst slurry is directly applied or sprayed onto the electrolyte membrane of the present invention to form a film, and then heated and dried to form a catalyst layer on the electrolyte membrane (in the case of containing a water repellent, the gas diffusion layer). A part of the water-repellent layer is formed). On this catalyst layer, an electrode is produced by subjecting a gas diffusion layer, such as carbon paper, optionally subjected to water repellent treatment to hot pressing.

The thickness of the catalyst layer at this time is suitably, for example, 0.1 to 1000 μm, preferably 1 to 500 μm, more preferably 2 to 200 μm.
As for the said catalyst slurry, it is desirable to adjust the viscosity to the range of 0.1-1000 Pa.s. This viscosity is either (a) selecting each particle size, (b) adjusting the composition of the catalyst particles and the binder, (c) adjusting the water content, or (d) Preferably, it can be adjusted by adding a viscosity modifier such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose or cellulose, polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone, sodium polyacrylate or polymethyl vinyl ether.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. An evaluation method of MEA obtained in this example is shown below.
<Measurement method and evaluation method>
(1) Measurement of ion exchange equivalent mass The polymer film made into the sulfonic acid type was dried under reduced pressure at 100 ° C for 24 hours, then transferred to a glove box in an argon atmosphere, and allowed to stand for 30 minutes, and then the mass was measured. This was added to 1.0 mol / l (liter) saline and titrated with a 0.05 mol / l (liter) ethanol solution of potassium hydroxide. The time when the pH reached 7 was taken as the equivalent point, and the ion exchange capacity was calculated from the amount of potassium hydroxide added at that time.
Formula for calculating ion exchange capacity:
Ion exchange capacity [meq / g] = 0.05 [mmol / ml] × potassium hydroxide titration [ml] / weight of polymer film [g]

Example 1
<Synthesis of copolymer>
A 200 mL 4-neck round bottom flask equipped with a Dean-Stark trap, condenser, stirrer and nitrogen supply tube was charged with sodium 4,4′-dichloro-3,3′-disulfonate diphenylsulfone monohydrate (15. 28 g, 0.03 mol), 4,4′-dichlorodiphenyl sulfone (5.74 g, 0.02 mol), BisP-DED (trade name, 16.32 g, 0.05 mol) manufactured by Honshu Chemical Industry Co., Ltd. Potassium carbonate (8.29 g, 0.06 mol), N-methylpyrrolidone: 55 mL, toluene: 43 mL were added, heated to 160 ° C. and stirred for 2 hours, then the temperature was raised to 190 ° C. and toluene was added. The mixture was stirred for 16 hours while distilling off. After cooling, the solution is poured into 1000 mL of water to precipitate the compound, filtered, sufficiently washed with purified water, and then dried in a hot air dryer at 140 ° C. for 5 hours to obtain the desired copolymer. Got.
Yield: 13.1 g, Yield: 39.5%, Number average molecular weight: 54000, Dispersity: 4.5
Ion exchange equivalent mass value (EW value): 485
Structural formula: As shown in the following chemical formula (4).

<Preparation of binder varnish>
45 g of methyl cellosolve was added to 5 g of the copolymer obtained in Example 1, and the mixture was stirred for 24 hours at room temperature (25 ° C.), dissolved, and a binder varnish was prepared to 5 mass%.

<Preparation of electrolyte membrane>
To a 1000 mL four-necked round bottom flask equipped with a Dean-Stark trap, condenser, stirrer and nitrogen supply tube was added sodium 4,4′-dichloro-3,3′-disulfonate diphenylsulfone monohydrate (76.76). 4 g, 0.150 mol), 4,4′-dichlorodiphenylsulfone (21.54 g, 0.750 mol), 4,4′-dihydroxybiphenyl (46.55 g, 0.250 mol), potassium carbonate (41.4 mol). 46 g, 0.30 mol), N-methylpyrrolidone: 230 mL, toluene: 270 mL, heated to 160 ° C. and stirred for 2 hours, then the temperature was raised to 190 ° C., while toluene was distilled off. Stir for hours. The number average molecular weight of the polymer at this time was 1770. After cooling to 110 ° C., difluorobiphenyl sulfone (6.36 g, 0.025 mol) and N-methylpyrrolidone: 230 mL were added and stirred for 1 hour, and then stirred at 180 ° C. for 25 hours. After cooling, this solution is poured into 2500 mL of water to precipitate the compound, filtered, sufficiently washed with purified water, and then dried in a hot air dryer at 140 ° C. for 5 hours, whereby the target co-polymer is recovered. Coalescence was obtained.
Yield: 137.7 g, Yield: 93.5%, Number average molecular weight: 141390, Dispersity: 6.2
Ion exchange equivalent mass value (EW value): 414
Structural formula: As shown in the following chemical formula (5).

<Preparation of electrolyte membrane>
After 15 g of the obtained copolymer was dissolved in 85 g of N-methylpyrrolidone, it was filtered under pressure using a 1000 mesh filter and further defoamed with a planetary stirring type defoaming device. This solution was cast on a glass plate using a bar coater having a gap of 400 μm, and then dried with a hot air dryer at 60 ° C. for 15 minutes, 80 ° C. for 15 minutes, and 100 ° C. for 15 minutes.
After taking out from the dryer, the film was peeled off from the glass plate, fixed to a stainless steel frame, poured again into the dryer, and dried at 160 ° C.-30 minutes and 200 ° C.-30 minutes. After cooling to room temperature (25 ° C.), the membrane was removed from the frame and impregnated with a 10% by mass sulfuric acid aqueous solution for 12 hours at room temperature (25 ° C.). After washing with distilled water, the water adhering to the membrane was wiped off with filter paper (No. 5A) to produce an electrolyte membrane.

<Preparation of membrane electrode assembly>
Catalyst supported carbon particles having a platinum loading of 50% by mass (trade name: TEC10V50E, manufactured by Tanaka Kikinzoku Co., Ltd.): After 1.0 g is dampened in water, a Nafion (trade name, manufactured by DuPont Co., Ltd.) solution (5 (Mass%): Catalyst paste A (viscosity: 3.0 Pa · s) was prepared by mixing and dispersing 10 g in a uniform manner.
Then, using a spray coater (manufactured by Nordson Co., Ltd., trade name: slurry coating apparatus III), the catalyst paste A is applied to one side on the electrolyte membrane obtained in Example 1 and dried to form a catalyst layer. A was formed. In addition, the catalyst-carrying carbon particles (trade name: TEC61E54, manufactured by Tanaka Kikinzoku Co., Ltd.) having a platinum-carrying amount of 30% by mass and a ruthenium-carrying amount of 24% by mass were wetted with 1.0 g. Catalyst paste B (viscosity: 3.5 Pa · s) was prepared by mixing and dispersing 8 g of the binder varnish obtained in Example 1 so as to be uniform. By applying and drying this catalyst paste B using a spray coater, a catalyst layer B is formed on the opposite side of the catalyst layer A on the electrolyte membrane obtained in Example 1, and obtained in Example 1. Catalyst layers A and B were formed on both sides of the electrolyte membrane to obtain a membrane electrode assembly.
Subsequently, the prepared membrane electrode assembly is sandwiched between press plates of a flat plate press, and is sandwiched for 3 minutes at 120 ° C. and 5 MPa, whereby the membrane electrode assembly 1 (catalyst layer A film thickness: 150 μm, catalyst) Layer B film thickness: 150 μm) was prepared.

<Fabrication of fuel cell>
As shown in FIG. 1, a sealing material (polytetrafluoroethylene sheet) 2 for preventing fuel leakage is disposed on both sides of the membrane electrode assembly (MEA1) obtained in Example 1, and one of the sealing materials 2 is disposed. The separator 3 on the anode side is disposed on the cathode side, the separator 3 on the cathode side is disposed on the other side, and the current collector plate 4 is disposed on each separator 3.
Finally, the whole was fixed with a special bolt, and a fuel cell (manufactured by Electrochem, Inc., trade name: FC05-01SP-REF, electrode area: 5 cm ² , electrode average pore diameter: 2 μm, electrode porosity: 40%, serpentine Flow).

(Example 2)
<Synthesis of copolymer>
A 200 mL 4-neck round bottom flask equipped with a Dean-Stark trap, condenser, stirrer and nitrogen supply tube was charged with sodium 4,4′-dichloro-3,3′-disulfonate diphenylsulfone monohydrate (15. 28 g, 0.03 mol), 4,4′-dichlorodiphenylsulfone (5.74 g, 0.02 mol), 4,4 ′-(2-ethylhexylidene) diphenol (14.92 g, 0.05) Mol), potassium carbonate (8.29 g, 0.06 mol), N-methylpyrrolidone: 55 mL, toluene: 43 mL, heated to 160 ° C. and stirred for 2 hours, then the temperature was raised to 190 ° C. The mixture was stirred for 15 hours while distilling off toluene. After cooling, the solution is poured into 1000 mL of water to precipitate the compound, filtered, sufficiently washed with purified water, and then dried in a hot air dryer at 140 ° C. for 5 hours to obtain the desired copolymer. Got.
Yield: 29.2 g, Yield: 91.9%, Number average molecular weight: 37800, Dispersity: 2.3
Ion exchange equivalent mass value (EW value): 632
Structural formula: As shown in chemical formula (6) below.

<Preparation of binder varnish>
A binder varnish was prepared in the same manner as in Example 1, except that the copolymer obtained in Example 2 was used instead of the copolymer obtained in Example 1.

<Preparation of membrane electrode assembly>
A membrane / electrode assembly 2 was produced in the same manner as in Example 1, except that the binder varnish obtained in Example 2 was used instead of the binder varnish obtained in Example 1.

<Fabrication of fuel cell>
A fuel cell was produced in the same manner as in Example 1 except that the membrane / electrode assembly 2 obtained in Example 2 was used.

(Comparative Example 1)
<Synthesis of copolymer>
To a 1000 mL four-necked round bottom flask equipped with a Dean-Stark trap, condenser, stirrer and nitrogen supply tube was added sodium 4,4′-dichloro-3,3′-disulfonate diphenylsulfone monohydrate (76.76). 4 g, 0.150 mol), 4,4′-dichlorodiphenylsulfone (21.54 g, 0.750 mol), 4,4′-dihydroxybiphenyl (46.55 g, 0.250 mol), potassium carbonate (41.4 mol). 46 g, 0.30 mol), N-methylpyrrolidone: 230 mL, toluene: 270 mL, heated to 160 ° C. and stirred for 2 hours, then the temperature was raised to 190 ° C., while toluene was distilled off. Stir for hours. The number average molecular weight of the polymer at this time was 1770. After cooling to 110 ° C., difluorobiphenyl sulfone (6.36 g, 0.025 mol) and N-methylpyrrolidone: 230 mL were added and stirred for 1 hour, and then stirred at 180 ° C. for 25 hours. After cooling, this solution is poured into 2500 mL of water, the compound is precipitated, filtered, sufficiently washed with purified water, and then dried in a hot air dryer at 140 ° C. for 5 hours to obtain the desired copolymer. Got.
Yield: 137.7 g, Yield: 93.5%, Number average molecular weight: 141390, Dispersity: 6.2
Ion exchange equivalent mass value (EW value): 414
Structural formula: As shown in the following general formula (7).

<Preparation of binder varnish>
A binder varnish was prepared in the same manner as in Example 1 except that the copolymer obtained in Comparative Example 1 was used instead of the copolymer obtained in Example 1.

<Preparation of membrane electrode assembly>
A membrane / electrode assembly 3 was produced in the same manner as in Example 1 except that the binder varnish obtained in Comparative Example 1 was used instead of the binder varnish obtained in Example 1.

<Fabrication of fuel cell>
A fuel cell was produced in the same manner as in Example 1 except that the membrane / electrode assembly 3 obtained in Comparative Example 1 was used.

(Comparative Example 2)
<Synthesis of copolymer>
A 200 mL 4-neck round bottom flask equipped with a Dean-Stark trap, condenser, stirrer and nitrogen supply tube was charged with sodium 4,4′-dichloro-3,3′-disulfonate diphenylsulfone monohydrate (15. 28 g, 0.03 mol), 4,4′-dichlorodiphenyl sulfone (5.74 g, 0.02 mol), BisP-AP (trade name, 14.52 g, 0.05 mol manufactured by Honshu Chemical Industry Co., Ltd.), Potassium carbonate (8.29 g, 0.06 mol), N-methylpyrrolidone: 55 mL, toluene: 43 mL were added, heated to 160 ° C. and stirred for 2 hours, then the temperature was raised to 190 ° C. and toluene was added. The mixture was stirred for 16 hours while distilling off. After cooling, the solution is poured into 1000 mL of water to precipitate the compound, filtered, sufficiently washed with purified water, and then dried in a hot air dryer at 140 ° C. for 5 hours to obtain the desired copolymer. Got.
Yield: 28.1 g, Yield: 89.5%, Number average molecular weight: 48500, Dispersity: 2.7
Ion exchange equivalent mass value (EW value): 634
Structural formula: As shown in the following general formula (8).

<Preparation of binder varnish>
A binder varnish was prepared in the same manner as in Example 1 except that the copolymer obtained in Comparative Example 2 was used instead of the copolymer obtained in Example 1.

<Preparation of membrane electrode assembly>
A membrane / electrode assembly 4 was produced in the same manner as in Example 1 except that the binder varnish obtained in Comparative Example 2 was used instead of the binder varnish obtained in Example 1.

<Fabrication of fuel cell>
A fuel cell was produced in the same manner as in Example 1 except that the membrane electrode assembly 4 obtained in Comparative Example 2 was used.

  Hydrogen was supplied to the cathode side and nitrogen was supplied to the anode side of the fuel cells prepared in Examples 1 and 2 and Comparative Examples 1 and 2, and the effective catalyst surface area of Pt in the anode catalyst layer was measured. The results are summarized in Table 1.

  For the fuel cells using the membrane electrode assemblies of Examples 1 and 2 and Comparative Example 1 in FIG. 2, 10% by mass methanol aqueous solution is 1 ml / min on the anode side, air is 300 ml / min on the cathode side, cell temperature The output characteristics under the condition of 60 ° C. are shown.

It is a schematic perspective view which shows the structure of the fuel cell of this invention. It is a figure which shows the relationship between a current density and an output density.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... MEA, 2 ... Sealing material, 3 ... Separator, 4 ... Current collecting plate

Claims (8)

  A membrane electrode assembly using a hydrocarbon electrolyte membrane.   2. The membrane electrode assembly according to claim 1, wherein a hydrocarbon binder is used for the electrode. 3. The membrane electrode assembly according to claim 2, wherein the hydrocarbon binder includes a structural unit represented by the following general formula (1).

[Wherein A represents an alkylene group having 5 to 20 carbon atoms. B, C, D, and E represent hydrogen and fluorine. ]   The hydrophobic binder according to claim 2 or 3, wherein the hydrocarbon binder does not contain a hydrophilic part containing at least one of a sulfonic acid group, a phosphoric acid group and a carboxyl group and a sulfonic acid group, a phosphoric acid group or a carboxyl group. Membrane electrode assembly which is a copolymer with a part. The membrane electrode assembly according to any one of claims 2 to 4, wherein the copolymerization component of the hydrocarbon binder is represented by the following general formula (2).

[Wherein A represents an alkylene group having 5 to 20 carbon atoms. x is mol%. ]   6. The membrane electrode assembly according to claim 1, wherein an electrode is formed on the hydrocarbon electrolyte membrane by using a spray coating method, a GDE method, or a transfer method.   7. The membrane electrode assembly according to claim 1, wherein a catalyst slurry containing a noble metal catalyst is spray-coated on a hydrocarbon electrolyte membrane, and an electrode is directly formed on the electrolyte membrane.   8. The membrane electrode assembly according to claim 7, wherein the catalyst slurry includes a noble metal catalyst, an electrolyte binder, and a solvent, and the noble metal catalyst and the electrolyte binder are dissolved or dispersed in the solvent.

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