JP4871537B2 - Method for producing membrane-electrode assembly - Google Patents

Description

  The present invention relates to a method for producing a membrane-electrode assembly having a solid polymer electrolyte membrane used for a solid polymer electrolyte fuel cell or the like.

  A solid polymer electrolyte fuel cell has a membrane-electrode assembly including a polymer electrolyte membrane sandwiched between a pair of catalyst layers, and pure hydrogen or reformed hydrogen gas is used as a fuel gas in one catalyst layer ( To the fuel electrode), and oxygen gas or air as an oxidant is supplied to the other catalyst layer (air electrode) to obtain an electromotive force.

  As a method for producing the membrane-electrode assembly, for example, a catalyst paste containing carbon particles carrying a metal catalyst, a hydrogen ion conductive polymer electrolyte, and an organic solvent is applied to both surfaces of the polymer electrolyte membrane. After coating or spraying, removing the organic solvent by heating and drying to form a catalyst layer on both sides of the polymer electrolyte membrane, a gas diffusion layer such as carbon paper is placed on both sides of the catalyst layer, and hot pressing to the catalyst layer and the gas The method of joining a diffused layer is mentioned.

  When a sulfonated perfluorohydrocarbon polymer electrolyte typified by Nafion (registered trademark) is used as the polymer electrolyte constituting the catalyst layer, the polymer electrolyte is thermoplastic, so hot pressing, etc. The catalyst layer and the gas diffusion layer can be easily joined by the thermocompression bonding method.

  On the other hand, when a heat-resistant material such as a protonic acid group-containing aromatic polymer such as sulfonated polyarylene (for example, see Patent Document 1) is used as the polymer electrolyte, the temperature exceeds the deterioration temperature of the catalyst metal. Unless the pressure conditions were such that the pores in the catalyst layer were crushed, sufficient bonding strength could not be realized.

As described above, when the bonding strength between the catalyst layer and the gas diffusion layer is not sufficient, voids are generated between the gas diffusion layer and the catalyst layer, particularly under the operating conditions of high humidification and high current density, resulting in flatting. It becomes easy. When flatting occurs, not only the initial power generation performance decreases, but also it becomes difficult to obtain stable power generation performance for a long time. Further, if the fuel gas supply is delayed due to the occurrence of flatting on the fuel electrode side, the carbon paper on the electrode substrate and the carbon particles supporting the catalyst may be corroded to shorten the life of the fuel cell.
US Pat. No. 5,403,675

  An object of the present invention is to improve the bonding strength between a catalyst layer containing a protonic acid group-containing aromatic polymer formed on both surfaces of a solid polymer electrolyte membrane and a gas diffusion layer bonded on the catalyst layer Another object of the present invention is to provide a method for producing a solid polymer membrane-electrode assembly having excellent power generation durability.

  The inventors of the present invention have intensively studied to solve the above problems. As a result, the bonding strength between the catalyst layer and the gas diffusion layer is improved by bonding the catalyst layer and the gas diffusion layer through an adhesive layer containing a specific protonic acid group-containing aromatic polymer. The present inventors have found that this can be done and have completed the present invention.

That is, the method for producing a membrane-electrode assembly according to the present invention has both sides of a solid polymer electrolyte membrane,
A method for producing a membrane-electrode assembly having a catalyst layer containing a proton acid group-containing aromatic polymer and carbon particles carrying a metal catalyst, and having a gas diffusion layer on the catalyst layer, It includes a step of joining at least one of the catalyst layer and the gas diffusion layer with an adhesive layer containing a protonic acid group-containing aromatic polymer interposed therebetween.

  The protonic acid group-containing aromatic polymer constituting the adhesive layer is preferably the same as the protonic acid group-containing aromatic polymer constituting the catalyst layer, and the polymer is a sulfone having a specific structural unit. More preferred is a modified polyarylene.

  The adhesive layer may further contain a conductive filler, and the mass ratio of the protonic acid group-containing aromatic polymer and the conductive filler to 5/95 to 60/40 (polymer / filler). It is preferable to contain.

  According to the present invention, since the catalyst layer and the gas diffusion layer formed on the solid polymer electrolyte membrane can be bonded with sufficient bonding strength, a membrane-electrode assembly having excellent power generation durability is obtained. be able to.

  The membrane-electrode assembly obtained by the production method of the present invention has an electrode layer including a catalyst layer and a gas diffusion layer, and a solid polymer electrolyte membrane, and a catalyst layer is formed on both sides of the electrolyte membrane, A gas diffusion layer is bonded on the catalyst layer. And the manufacturing method of the membrane-electrode assembly of this invention includes the process of joining at least one catalyst layer and a gas diffusion layer through the adhesive layer containing a protonic acid group containing aromatic polymer interposed. It is characterized by that. Hereinafter, the manufacturing method of the membrane-electrode assembly according to the present invention and the constituent materials used in the manufacturing method will be described in detail.

(Catalyst layer)
The catalyst layer constituting the membrane-electrode assembly obtained by the production method of the present invention contains carbon carrying a catalyst and a protonic acid group-containing aromatic polymer.

(I) Carbon carrying a catalyst As the catalyst used in the present invention, platinum or a platinum alloy is used. When a platinum alloy is used, stability and activity as an electrode catalyst can be further imparted. Such platinum alloys include platinum group metals other than platinum (ruthenium, rhodium, palladium, osmium, iridium), iron, cobalt, titanium, gold, silver, chromium, manganese, molybdenum, tungsten, aluminum, silicon, rhenium. An alloy of platinum and one or more selected from zinc and tin is preferable, and the platinum alloy may contain an intermetallic compound of a metal alloyed with platinum.

  As the carbon supporting the catalyst, carbon black such as oil furnace black, channel black, lamp black, thermal black, and acetylene black is preferably used from the viewpoint of electron conductivity and specific surface area. Further, artificial graphite or carbon obtained from organic compounds such as natural graphite, pitch, coke, polyacrylonitrile, phenol resin, furan resin, and the like may be used.

Examples of the oil furnace black include “Vulcan XC-72”, “Vulcan P”, “Black Pearls 880”, “Black Pearls 1100”, “Black Pearls 1300”, “Black Pearls 2000”, and “Regal 400” manufactured by Cabot Corporation. “Ketjen Black EC” manufactured by Lion, “# 3150” manufactured by Mitsubishi Chemical Corporation, “# 3250”, and the like. Examples of the acetylene black include “DENKA BLACK” manufactured by Denki Kagaku Kogyo.

  As the form of these carbons, in addition to particles, fibers can also be used. The amount of the catalyst supported on the carbon is not particularly limited as long as it can effectively exhibit the catalytic activity, but the supported amount is 0.1 to 9.0 g- Metal / g-carbon, preferably in the range of 0.25 to 2.4 g-metal / g-carbon.

(Ii) Protonic acid group-containing aromatic polymer The protonic acid group-containing aromatic polymer constituting the catalyst layer serves as a binder component for binding the carbon carrying the catalyst, and the reaction on the catalyst at the fuel electrode In the air electrode, ions supplied from the ion conductive membrane are efficiently supplied to the catalyst.

  The protonic acid group-containing aromatic polymer is not particularly limited as long as it has the above functions, but does not have a polymer segment (A) having an ion conductive component composed of a sulfonic acid group or a phosphoric acid group and an ion conductive component. A block copolymer in which the polymer segment (B) is covalently bonded is preferable. More preferably, the main chain skeleton forming the copolymer is a polyarylene having a structure in which an aromatic ring is covalently bonded with a linking group, and particularly preferably a structural unit represented by the following general formula (A) (Hereinafter also referred to as “structural unit (A)” or “sulfonic acid unit”) and a structural unit represented by the following general formula (B) (hereinafter referred to as “structural unit (B)” or “hydrophobic unit”). And a polyarylene having a sulfonic acid group represented by the following general formula (C) (hereinafter also referred to as “sulfonated polyarylene”). When such a sulfonated polyarylene is used, an electrode catalyst layer having higher heat resistance and higher mechanical strength can be formed. Hereinafter, the sulfonated polyarylene particularly preferably used in the present invention will be described in detail.

<Sulfonated polyarylene>
(Sulfonic acid unit)

In the above formula (A), Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—.
_{, - (CF 2) i -} (i is an integer from 1 to 10.) Or -C (CF _{3) 2} - shows a. Of these, —CO— and —SO ₂ — are preferable.

Z independently represents a direct bond, — (CH ₂ ) _j — (j represents an integer of 1 to 10), —C (CH ₃ ) ₂ —, —O— or —S—. Among these, a direct bond and —O— are preferable.

Ar is —SO ₃ H, —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H (p is 1 to
An integer of 12 is shown. The aromatic group which has a substituent represented by this is shown. Examples of the aromatic group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and the like. In these, a phenyl group and a naphthyl group are preferable. Ar represents —SO ₃ H;
It is necessary to have at least one substituent represented by —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H, and two in the case of a naphthyl group It is preferable to have the above.

m is an integer of 0 to 10, preferably 0 to 2, n is an integer of 0 to 10, preferably 0 to 2, and k is an integer of 1 to 4.
As a preferred structure of the structural unit (A), in the above formula (A),
(1) a structure in which m = 0, n = 0, Y is —CO—, and Ar is a phenyl group having —SO ₃ H as a substituent;
(2) a structure in which m = 1, n = 0, Y is —CO—, Z is —O—, and Ar is a phenyl group having —SO ₃ H as a substituent;
(3) A structure in which m = 1, n = 1, k = 1, Y is —CO—, Z is —O—, and Ar is a phenyl group having —SO ₃ H as a substituent;
(4) m = 1, n = 0, Y is —CO—, and Ar is two substituents —SO _3.
A structure which is a naphthyl group having H,
(5) m = 1, n = 0, Y is —CO—, Z is —O—, and Ar is a phenyl group having —O (CH ₂ ) ₄ SO ₃ H as a substituent. Examples include structures.

  (Hydrophobic unit)

In the above formula (B), A and D are each independently a direct bond, —CO—, —SO ₂ —, —
SO—, —CONH—, —COO—, — (CF ₂ ) _i — (i represents an integer of 1 to 10), — (CH ₂ ) _j — (j represents an integer of 1 to 10) , -CR _'2 -, showing cyclohexylidene group, a fluorenylidene group, -O- or -S-. Among these, a direct bond, —CO—, —SO ₂ —, —CR ′ ₂ —, a cyclohexylidene group, a fluorenylidene group, and —O— are preferable. R ′ represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group or a halogenated hydrocarbon group. For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, A propyl group, an octyl group, a decyl group, an octadecyl group, a phenyl group, a trifluoromethyl group, etc. are mentioned.

B independently represents an oxygen atom or a sulfur atom, preferably an oxygen atom.
R ^{1 to} R ¹⁶ each independently represent a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group, an allyl group, an aryl group, a nitro group or a nitrile group, which is partially or wholly halogenated.

Examples of the alkyl group in R ^{1 to} R ¹⁶ include a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a hexyl group, a cyclohexyl group, and an octyl group. Examples of the halogenated alkyl group include a trifluoromethyl group, a pentafluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group. Examples of the allyl group include a propenyl group. Examples of the aryl group include a phenyl group and a pentafluorophenyl group.

s and t each represent an integer of 0 to 4. r shows 0 or an integer greater than or equal to 1, and an upper limit is 100 normally, Preferably it is 1-80.
As a preferred structure of the structural unit (B), in the above formula (B),
(1) s = 1, t = 1, A is —CR ′ ₂ —, a cyclohexylidene group or a fluorenylidene group, B is an oxygen atom, and D is —CO— or —SO ₂ —. , R ^{1 to} R ¹⁶ are hydrogen atoms or fluorine atoms,
(2) A structure in which s = 1, t = 0, B is an oxygen atom, D is —CO— or —SO ₂ —, and R ^{1 to} R ¹⁶ are hydrogen atoms or fluorine atoms,
(3) s = 0, t = 1, A is —CR ′ ₂ —, a cyclohexylidene group or a fluorenylidene group, B is an oxygen atom, and R ^{1 to} R ¹⁶ are a hydrogen atom, a fluorine atom or Examples thereof include a structure that is a nitrile group.

  (Polymer structure)

In the above formula (C), A, B, D, Y, Z, Ar, k, m, n, r, s, t and R ^{1 to} R ¹⁶ are defined in the above formulas (A) and (B). Where x and y are x + y = 10
The molar ratio in the case of 0 mol% is shown.

  The sulfonated polyarylene particularly preferably used in the present invention contains the structural unit (A), that is, the unit of x in a proportion of 0.5 to 99.999 mol%, preferably 10 to 99.99 mol%, The structural unit (B), that is, the y unit is contained in a proportion of 99.5 to 0.001 mol%, preferably 90 to 0.01 mol%.

(Method for producing sulfonated polyarylene)
Examples of the method for producing the sulfonated polyarylene include the following methods A, B, and C.

(Method A) For example, in the method described in JP-A No. 2004-137444, a monomer having a sulfonate group that can be the structural unit (A) and a monomer or oligomer that can be the structural unit (B) are combined. A method of polymerizing to produce a polyarylene having a sulfonic acid ester group, and deesterifying the sulfonic acid ester group to convert it into a sulfonic acid group.

  (Method B) For example, in the method described in JP-A-2001-342241, a monomer having a skeleton represented by the above formula (A) but not having a sulfonic acid group or a sulfonic acid ester group, and the above structural unit (B) A method in which a monomer or an oligomer that can be used is copolymerized, and the resulting copolymer is sulfonated using a sulfonating agent.

(Method C) When Ar in the above formula (A) is an aromatic group having a substituent represented by —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H Is, for example, copolymerized a precursor monomer that can be the structural unit (A) and a monomer or oligomer that can be the structural unit (B) by the method described in JP-A-2005-60625, A method of introducing an alkyl sulfonic acid or a fluorine-substituted alkyl sulfonic acid.

  Examples of the monomer having a sulfonate group that can be the structural unit (A) that can be used in the method A include, for example, JP-A Nos. 2004-137444, 2004-345997, and 2004-346163. Examples thereof include sulfonic acid esters described in Japanese Patent Publication No. Gazette.

  Examples of the monomer that does not have a sulfonic acid group and a sulfonic acid ester group that can be used as the structural unit (A) and that can be used in the above-mentioned method B include, for example, JP-A Nos. 2001-342241 and 2002-293889. Mention may be made of the dihalides described.

  Examples of the precursor monomer that can be the structural unit (A) that can be used in the method C include dihalides described in JP-A-2005-36125.

Moreover, as a monomer or oligomer that can be the structural unit (B) used in any method,
When r = 0, for example, 4,4′-dichlorobenzophenone, 4,4′-dichlorobenzanilide, 2,2-bis (4-chlorophenyl) difluoromethane, 2,2-bis (4-chlorophenyl) -1 , 1,1,3,3,3-hexafluoropropane, 4-chlorobenzoic acid-4-chlorophenyl ester, bis (4-chlorophenyl) sulfoxide, bis (4-chlorophenyl) sulfone, 2,6-dichlorobenzonitrile, etc. Is mentioned. Among these compounds, compounds in which a chlorine atom is replaced with a bromine atom or an iodine atom can also be used.

In the case of r = 1, for example, compounds described in JP-A-2003-113136 can be exemplified.
In the case of r ≧ 2, for example, JP 2004-137444 A, JP 2004-244517 A, JP 2004-346164 A, Japanese Patent Application No. 2003-348523, Japanese Patent Application No. 2003-348524, and Japanese Patent Application No. 2004-2004. Examples thereof include compounds described in No. 211739 and Japanese Patent Application No. 2004- 211740.

In order to obtain a polyarylene having a sulfonic acid group, first, a monomer that can be the structural unit (A) and a monomer or oligomer that can be the structural unit (B) are copolymerized in the presence of a catalyst, It is necessary to obtain body polyarylene. The catalyst used in carrying out the copolymerization is a catalyst system containing a transition metal compound, and this catalyst system is (i) a compound that becomes a transition metal salt and a ligand, or a ligand is coordinated. Transition metal complex (including copper salt) and (ii) a reducing agent as essential components, and further, a “salt” for increasing the polymerization rate
May be added. For example, the conditions described in JP-A-2001-342241 can be adopted as specific examples of these catalyst components, the use ratio of each component, the reaction solvent, concentration, temperature, time, and other polymerization conditions.

  The sulfonated polyarylene used in the present invention can be obtained by converting the precursor polyarylene obtained as described above into a polyarylene having a sulfonic acid group. As this method, there are the following three methods.

(Method a) A method of deesterifying the precursor polyarylene having a sulfonate group obtained by Method A by the method described in JP-A-2004-137444.
(Method b) A method of sulfonating the precursor polyarylene obtained in Method B by the method described in JP-A-2001-342241.

(Method c) A method of introducing an alkylsulfonic acid group into the precursor polyarylene obtained by the method C by the method described in JP-A-2005-60625.
The ion exchange capacity of the sulfonated polyarylene represented by the above formula (C) produced by the method as described above is usually 0.3 to 5 meq / g, preferably 0.5 to 3 meq / g, Preferably it is 0.8-2.8 meq / g. If the ion exchange capacity is lower than the above range, the proton conductivity tends to be low and the power generation performance tends to be reduced. On the other hand, if the ion exchange capacity exceeds the above range, the water resistance may be significantly lowered, which is not preferable.

  The ion exchange capacity can be adjusted, for example, by changing the type, use rate, and combination of the precursor monomer that can be the structural unit (A) and the monomer or oligomer that can be the structural unit (B).

  The molecular weight of the polyarylene having a sulfonic acid group thus obtained is 10,000 to 1,000,000, preferably 20,000 to 800,000 in terms of polystyrene-equivalent weight average molecular weight by gel permeation chromatography (GPC).

[Method of forming catalyst layer]
The method for forming the catalyst layer on the polymer electrolyte membrane described below is not particularly limited. For example, a proton acid group-containing aromatic polymer, carbon particles supporting the catalyst, and an organic solvent are mixed. The catalyst paste composition is prepared, applied onto the polymer electrolyte membrane and dried to prepare an electrode catalyst layer, or the catalyst paste composition is applied onto the transfer substrate and dried to form a catalyst on the transfer substrate. Examples thereof include a method of transferring the catalyst layer onto the polymer electrolyte membrane by thermal transfer such as hot pressing after forming the layer.

  Although it does not specifically limit as said organic solvent, It is preferable that a boiling point (bp) is 75-250 degreeC. When the boiling point of the organic solvent is less than the above range, the drying property of the catalyst paste is fast and the die nozzle is likely to be clogged. Then, it becomes difficult to remove the solvent, the pores in the electrode are blocked, and the power generation performance may be reduced.

The organic solvent preferably has a solubility parameter (δ) in the range of 7.5 to 13 (cal / mol) ^1/2 . When the solubility parameter of the organic solvent is out of the above range, the solubility of the protonic acid group-containing aromatic polymer is lowered, the coating of the polymer on the carbon carrying the catalyst becomes excessive, and the pores in the catalyst layer Tend to block.

Further, the organic solvent is, -O -, - OH, -CO -, - SO -, - SO 2 -, - COO
It is preferable to have at least one group selected from the group consisting of-and -CONR- (R is a hydrogen atom or a hydrocarbon group).

Examples of the organic solvent as described above include ethanol (bp: 78.3 ° C., δ: 12.92), n-propyl alcohol (bp: 97 ° C., δ: 11.97), 2-propanol (bp: 82.4 ° C., δ: 11.50), 2-methyl-2-propanol (bp: 82.5 ° C., δ: 11.11), 2-butanol (bp: 99.5 ° C., δ: 11.11) *),
n-butyl alcohol (bp: 117 ° C., δ: 11.30), 2-methyl-1-propanol (bp: 108 ° C., δ: 11.11 *), 1-pentanol (bp: 138 ° C., δ:
10.96 *), 2-pentanol (bp: 119 ° C., δ: 10.77 *), 3-pentanol (bp: 115 ° C., δ: 10.77 *), 2-methyl-1-butanol ( bp: 12
9 ° C., δ: 10.77 *), 3-methyl-1-butanol (bp: 131 ° C., δ: 10.
77 *), 2-methyl-2-butanol (bp: 102 ° C., δ: 10.58 *), 3-methyl-2-butanol (bp: 112 ° C., δ: 10.58 *), 2,2- Dimethyl 1-propanol (bp: 113 ° C., δ 10.58 *), cyclohexanol (bp: 161 ° C., δ: 12.44 *), 1-hexanol (bp: 157 ° C., δ: 10.68 *), 2-methyl-1-pentanol (bp: 148 ° C., δ: 10.51 *), 2-methyl-2-pentanol (bp: 121 ° C., δ: 10.34 *), 4-methyl-2- Pentanol (bp:
132 ° C., δ: 10.34 *), 2-ethyl-1-butanol (bp: 147 ° C., δ: 1)
0.51 *), 1-methylcyclohexanol (bp: 156, δ: 11.76 *), 2-methylcyclohexanol (bp: 168 ° C., δ: 11.74 *), 3-methylcyclohexanol (bp : 168 ° C., δ: 11.74 *), 4-methylcyclohexanol (b
p. 171 ° C., δ: 11.74 *), 1-octanol (bp. 195 ° C., δ 10.28 *), 2-octanol (bp: 180 ° C., δ: 10.14 *), 2-ethyl-1- Hexanol (bp: 184 ° C., δ: 10.14 *), dioxane (bp: 101 ° C., δ: 10
. 0), butyl ether (bp: 140 ° C., δ: 7.78 *), phenyl ether (bp
187 ° C., δ: 12.16), isopentyl ether (bp: 173 ° C., δ: 7.63 *), 1,2-dimethoxyethane (bp: 85.2, δ: 7.63 *), di Ethoxyethane (bp: 102 ° C., δ: 7.63 *), bis (2-methoxyethyl) ether (bp:
160 ° C., δ: 8.10 *), bis (2-ethoxyethyl) ether (bp: 189 ° C.,
δ: 8.19 *), cineol (bp: 176 ° C., δ: 8.97 *), benzyl ethyl ether (bp: 185 ° C., δ: 9.20 *), anisole (bp: 154 ° C., δ: 9) .38 *), phenetole (bp: 170 ° C., δ: 9.27 *), acetal (bp: 104 ° C.,
δ: 7.65 *), methyl ethyl ketone (bp: 79.6, δ: 9.27), 2-pentanone (bp: 102 ° C., δ: 8.30 *), 3-pentanone (bp: 102 ° C., δ : 8.
30 *), cyclopentanone (bp: 131 ° C., δ: 12.81 *), cyclohexanone (bp: 156 ° C., δ: 9.88), 2-hexanone (bp: 128 ° C., δ: 8.84 *) )
4-methyl-2-pentanone (bp: 117 ° C., δ: 8.68 *), 2-heptanone (
bp: 151 ° C., δ: 8.84 *), 2,4-dimethyl-3-pentanone (bp: 125 ° C., δ: 8.49), 2-octanone (bp: 173 ° C., δ: 8.81 *) ), Γ-butyrolactone (bp: 204, δ: 12.78), n-butyl acetate (bp: 126 ° C., δ: 8.46), isobutyl acetate (bp: 126 ° C., δ: 8.42), Sec-butyl acetate (bp: 112 ° C., δ: 8.51 *), pentyl acetate (bp: 150 ° C., δ: 8.69 *), isopentyl acetate (bp: 142 ° C., δ: 8.52 *), 3-methoxybutyl acetate (bp
173 ° C., δ: 8.52 *), methyl butyrate (bp: 102 ° C., δ: 8.72 *), ethyl butyrate (bp: 121 ° C., δ: 8.70 *), methyl lactate (bp: 145 ° C, δ: 12.4
2 *), ethyl lactate (bp: 155 ° C., δ: 10.57), butyl lactate (bp: 185 ° C.)
, Δ: 11.26 *), 2-methoxyethanol (bp: 125 ° C., δ: 11.98 *), 2-ethoxyethanol (bp: 136 ° C., δ: 11.47 *), 2- (methoxymethoxy ) Ethanol (bp: 168 ° C., δ: 11.60 *), 2-isopropoxyethanol (bp: 142 ° C., δ: 10.92 *), 1-methoxy-2-propanol (bp: 12)
0 ° C., δ: 11.27 *), 1-ethoxy-2-propanol (bp: 132 ° C., δ: 1
0.92 *), dimethyl sulfoxide (bp: 189 ° C., δ: 12.93), N-methylformamide (bp: 185 ° C., δ: 12.93), N, N-dimethylformamide (bp: 153 ° C., δ: 12.14), N, N-diethylformamide (bp: 178 ° C., δ: 10.07 *), N, N-dimethylacetamide (bp: 166 ° C., δ: 11.12)
N-methyl-2-pyrrolidone (bp: 202 ° C., δ: 11.17), tetramethylurea (bp: 177.5 ° C., δ: 10.6), and the like.

The said organic solvent may be used individually by 1 type, or may be used in combination of 2 or more type. In the above examples, δ represents the value of the solubility parameter ((cal / mol) ^1/2 ), and the value after “*” is the calculated value of Fedors (RF Fedors, Polym. Eng. Sci 14 (2) 147 (1974)).

  The organic solvent is used in an amount of 5% to 95% by weight, preferably 15% to 90% by weight in the catalyst paste composition. By using the organic solvent in an amount within the above range, the composition becomes paste-like and suitable for handling, and a sufficient pore volume in the electrode necessary for power generation can be secured.

  Water may be further added to the catalyst paste composition as necessary. Addition of water to the catalyst paste composition has an effect of reducing heat generation during paste preparation. Water can be added in an amount of 0 to 70% by weight, preferably 2 to 30% by weight, in the catalyst paste composition. When the amount of water added is within the above range, heat generation during preparation of the catalyst paste can be efficiently reduced.

  You may add a dispersing agent to the said catalyst paste composition further as needed. When a dispersant is added to the catalyst paste composition, the catalyst paste composition is excellent in dispersibility, storage stability, and fluidity, and productivity during coating is improved.

Examples of the dispersant include surfactants such as anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants.
Examples of the anionic surfactant include oleic acid / N-methyltaurine, potassium oleate / diethanolamine salt, alkyl ether sulfate / triethanolamine salt, polyoxyethylene alkyl ether sulfate / triethanolamine salt, special modified polyether Amine salt of ester acid, amine salt of higher fatty acid derivative, amine salt of special modified polyester acid, amine salt of high molecular weight polyether ester acid, amine salt of special modified phosphoric acid ester, high molecular weight polyester acid amide amine salt, special fatty acid derivative Amidoamine salt, alkylamine salt of higher fatty acid, amidoamine salt of high molecular weight polycarboxylic acid, sodium laurate, sodium stearate, sodium oleyl sulfate sodium salt, cetyl Sulfate sodium salt, stearyl sulfate sodium salt, oleyl sulfate sodium salt, lauryl ether sulfate ester, sodium alkylbenzene sulfonate, oil-soluble alkylbenzene sulfonate, α-olefin sulfonate, higher alcohol phosphate monoester disodium Salt, higher alcohol phosphoric acid diester disodium salt, zinc dialkyldithiophosphate and the like.

Examples of the cationic surfactant include benzyldimethyl {2- [2- (P-1
, 1,3,3-tetramethylbutylphenoxy) ethoxy] ethyl} ammonium chloride, octadecylamine acetate, tetradecylamine acetate, octadecyltrimethylammonium chloride, tallow trimethylammonium chloride, dodecyltrimethylammonium chloride, coconut trimethylammonium chloride, Hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, palm dimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride, dioleyldimethylammonium chloride, 1-hydroxyethyl-2-tallow imidazoline quaternary salt, 2 -Heptadecenyl-hydroxyethyl ester Dazoline, stearamide ethyl diethylamine acetate, stearamide ethyl diethylamine hydrochloride, triethanolamine monostearate formate, alkyl pyridium salt, higher alkyl amine ethylene oxide adduct, polyacrylamide amine salt, modified polyacrylamide amine salt, And fluoroalkyl quaternary ammonium iodide.

Examples of the amphoteric surfactant include dimethyl coconut betaine, dimethyl lauryl betaine, sodium laurylaminoethylglycine, sodium laurylaminopropionate, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, amide betaine, imidazolinium betaine, lecithin, 3 -[Ω-fluoroaccanoyl-N-ethylamino] -1-propanesulfonic acid sodium, N- [3- (perfluorooctanesulfonamido) propyl] -N, N-dimethyl-N-carboxymethyleneammonium betaine, etc. Can be mentioned.

  Examples of the nonionic surfactant include coconut fatty acid diethanolamide (1: 2 type), coconut fatty acid diethanolamide (1: 1 type), bovine fatty acid diethanolamide (1: 2 type), and bovine fatty acid diethanolamide (1). : 1 type), oleic acid diethanolamide (1: 1 type), hydroxyethyl lauryl amine, polyethylene glycol lauryl amine, polyethylene glycol palm amine, polyethylene glycol stearyl amine, polyethylene glycol beef tallow amine, polyethylene glycol beef tallow propylene diamine, polyethylene glycol di Oleylamine, dimethyllaurylamine oxide, dimethylstearylamine oxide, dihydroxyethyllaurylamine oxide, perfluoroalkylamine oxide, poly Vinyl pyrrolidone, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, fatty acid ester of glycerin, fatty acid ester of pentaerythritol, fatty acid ester of sorbit, fatty acid ester of sorbitan And fatty acid esters of sugar.

  The said dispersing agent may be used individually by 1 type, or may be used in combination of 2 or more type. The dispersant is preferably a surfactant having a basic group, more preferably an anionic or cationic surfactant, and still more preferably a surfactant having a molecular weight of 5,000 to 30,000. .

  In the catalyst paste composition, the content of the dispersant is 0 wt% to 10 wt%, preferably 0 wt% to 2 wt%. When the content of the dispersant is within the above range, a catalyst paste composition excellent in dispersibility, storage stability and fluidity can be obtained.

  In the catalyst paste composition, the content of carbon on which the catalyst is supported is 1% by weight to 20% by weight, preferably 3% by weight to 15% by weight. When the content of the carbon on which the catalyst is supported is less than the above range, the electrode reaction rate may decrease. On the other hand, when the content exceeds the above range, the viscosity of the catalyst paste composition increases, and uneven coating occurs during coating. May occur.

  In the catalyst paste composition, the content of the protonic acid group-containing aromatic polymer is 0.5 wt% to 30 wt%, preferably 1 wt% to 15 wt%. If the content of the protonic acid group-containing aromatic polymer is less than the above range, it may not be able to serve as a binder and a catalyst electrode may not be formed. On the other hand, if the content exceeds the above range, pores in the catalyst electrode may not be formed. The volume tends to decrease.

  Although the preparation method of the said catalyst paste composition is not specifically limited, For example, it can prepare by mixing each said component by a predetermined ratio and knead | mixing by a conventionally well-known method. The order of mixing the components is not particularly limited. For example, all the components are mixed and stirred for a certain period of time, or components other than the dispersant are mixed and stirred for a certain period of time, and then the dispersant is added as necessary. It is preferable to add and to stir for a certain time. Moreover, you may adjust the quantity of an organic solvent as needed, and may adjust the viscosity of a composition.

  Examples of the method for applying the catalyst paste composition to the polymer electrolyte membrane include brush coating, brush coating, bar coater coating, knife coater coating, doctor blade method, screen printing, and spray coating.

  Moreover, after apply | coating on another base material (transfer base material) and forming a catalyst layer once, this catalyst layer may be transcribe | transferred to a polymer electrolyte membrane. As the transfer substrate in this case, a polytetrafluoroethylene (PTFE) sheet or a glass plate or a metal plate whose surface is treated with a release agent can be used.

The thickness of the applied coating film (that is, the thickness of the catalyst layer) is not particularly limited, but the metal supported as a catalyst is 0.05 to 4.0 mg / cm ² per unit surface area of the coating, preferably 0.00. It is desirable to exist in the catalyst layer in the range of 1 to 2.0 mg / cm ² . Within this range, sufficiently high catalytic activity is exhibited, and protons can be extracted efficiently.

  The removal of the solvent after the application of the catalyst paste composition is performed at a drying temperature of 20 ° C. to 180 ° C., preferably 50 ° C. to 160 ° C., and a drying time of 5 minutes to 600 minutes, preferably 30 minutes to 400 minutes. If necessary, it can be removed by immersion in water. The water immersion temperature is 5 ° C to 120 ° C, preferably 15 ° C to 95 ° C, and the water immersion time is 1 minute to 72 hours, preferably 5 minutes to 48 hours.

  The pore volume of the conductive sheet-like catalyst layer formed as described above is 0.1 to 3.0 ml / g- (electrode catalyst layer), preferably 0.2 to 2.0 ml / g- ( It is desirable to be in the range of the electrode catalyst layer. When the pore volume exceeds the above range, not only the mechanical properties tend to be lowered, but also the electron conduction and proton conduction paths are cut, and the power generation performance may be lowered. On the other hand, if the pore volume is less than the above range, the gas diffusibility is poor and the power generation performance may be reduced.

[Polymer electrolyte membrane]
The polymer electrolyte membrane constituting the membrane-electrode assembly is preferably made of a polymer having a proton exchange group. Examples of proton exchange groups include sulfonic acid groups, carboxylic acid groups, and phosphoric acid groups. Further, the polymer having such a proton exchange group is not particularly limited, and a known polymer can be used, for example, a proton exchange group-containing polymer composed of a fluoroalkyl ether side chain and a fluoroalkyl main chain, A polyarylene having a sulfonic acid group is preferably used. Among these, from the viewpoint of good heat resistance, polyarylene having a sulfonic acid group, particularly sulfonated polyarylene represented by the above formula (C) is preferable.

  The polymer electrolyte membrane should be prepared by a casting method or the like in which a proton exchange group-containing polymer as described above is dissolved or swollen in a solvent and cast onto a substrate to form a film. It is also possible to use a commercially available polymer electrolyte membrane.

[Gas diffusion layer]
The gas diffusion layer constituting the membrane-electrode assembly is not particularly limited, and an electrode substrate generally used in a fuel cell, for example, a porous conductive sheet mainly composed of a conductive substance is used. Can do.

  Examples of the conductive substance include a fired body from polyacrylonitrile, a fired body from pitch, a carbon material such as graphite and expanded graphite, stainless steel, molybdenum, and titanium. The form of the conductive material is not particularly limited, such as fibrous or particulate, but a fibrous conductive inorganic material (inorganic conductive fiber), particularly carbon fiber is preferable.

  As the porous conductive sheet using inorganic conductive fibers, any structure of woven fabric and non-woven fabric can be used. As the woven fabric, plain weaving, oblique weaving, satin weaving, crest weaving, binding weaving and the like can be used without particular limitation. Moreover, as a nonwoven fabric, what was manufactured by methods, such as a papermaking method, a needle punch method, a spun bond method, a water jet punch method, a melt blow method, can be used without being specifically limited. The porous conductive sheet using inorganic conductive fibers may be a knitted fabric.

  In particular, when carbon fibers are used as such a fabric, a woven fabric obtained by carbonizing or graphitizing a plain fabric using a flame-resistant spun yarn, and processing the nonwoven fabric by a needle punch method, a water jet punch method, or the like, Carbonized or graphitized nonwoven fabrics, flame-resistant yarns, mat nonwoven fabrics made by paper making using carbonized yarns or graphitized yarns, and the like are preferable. For example, Toray carbon paper TGP series, SO series, E-TEK carbon cloth, etc. are preferably used.

It is also preferable to add conductive particles such as carbon black and conductive fibers such as carbon fibers as an auxiliary agent to the porous conductive sheet in order to improve conductivity.
[Adhesive layer]
In the method for producing a membrane-electrode assembly of the present invention, the adhesive layer interposed between the catalyst layer and the gas diffusion layer when the at least one catalyst layer and the gas diffusion layer are bonded is a protonic acid group. It is preferable to contain a containing aromatic polymer, and in particular, it is preferable to contain the same proton acid group-containing aromatic polymer contained in the catalyst layer. By bonding such an adhesive layer at the bonding interface, the bonding strength between the gas diffusion layer and the catalyst layer can be improved.

  In addition, the adhesive layer preferably contains a conductive filler in order to maintain good conductivity between the catalyst layer and the gas diffusion layer. As such a conductive filler, for example, carbon powder, carbon (carbon) fiber, fullerene, carbon nanotube, carbon nanofiber, and silicon carbide whisker whose surface is coated with a carbon film can be used. These may be used alone or in combination of two or more.

  The shape of the conductive filler used in the present invention is not particularly limited, and any shape such as granular or fibrous can be used, but a fibrous one is preferable from the viewpoint of securing the pore volume. Moreover, as a magnitude | size, Preferably it is 30 mm, More preferably, it is 1 mm or less. If the size exceeds the above range, it may protrude to the surface of the electrode catalyst layer and damage the proton conducting membrane.

  As the carbon powder, carbon black such as oil furnace black, channel black, lamp black, thermal black, and acetylene black is preferable from the viewpoint of electron conductivity and specific surface area.

As the above oil furnace black, “Vulcan XC-72”, “
"Vulcan P", "Black Pearls 880", "Black Pearls 1100", "Black Pearls 1300", "Black Pearls 2000", "Regal 400", Lion Corporation "Ketjen Black EC", Mitsubishi Chemical Corporation "# 3150 And “# 3250”. Examples of the acetylene black include “DENKA BLACK” manufactured by Denki Kagaku Kogyo.

  Examples of the carbon fiber include rayon-based carbon fiber, PAN-based carbon fiber, lignin pover-based carbon fiber, pitch-based carbon fiber, and vapor-grown carbon fiber. Among these, vapor-grown carbon fiber is preferable.

  The adhesive layer preferably contains the protonic acid group-containing aromatic polymer and the conductive filler in a mass ratio (polymer / filler) of 5/95 to 60/40. When the content of the protonic acid group-containing aromatic polymer is less than the above range, it is difficult to obtain sufficient adhesive strength. On the other hand, when the content exceeds the above range, the resistance of the adhesive layer becomes too high. As a result, the pores of the adhesive layer are clogged, and the gas diffusibility may be significantly reduced.

[Method of forming adhesive layer]
The method for interposing the adhesive layer in the present invention at the bonding interface between the gas diffusion layer and the catalyst layer is not particularly limited, and examples thereof include the following methods.
(1) An adhesive composition containing a conductive filler, a protonic acid group-containing aromatic polymer, and an organic solvent is applied or sprayed on the surface of the gas diffusion layer that contacts the catalyst layer or the surface of the catalyst layer that contacts the gas diffusion layer. And removing the organic solvent by heat drying to form an adhesive layer.
(2) The adhesive layer composition is applied to a transfer substrate, the organic solvent is removed by heating and drying to form an adhesive layer on the transfer substrate, and then the transfer substrate is heated by a thermal transfer method such as hot pressing. A method of transferring an adhesive layer to a surface of a gas diffusion layer in contact with a catalyst layer or a surface of a catalyst layer in contact with a gas diffusion layer.

  Although it does not specifically limit as said organic solvent, It is preferable that a boiling point (bp) is 75-250 degreeC. If the boiling point of the organic solvent is less than the above range, the drying property of the adhesive composition is fast, and the productivity of the coating may decrease due to the phenomenon that the nozzle of the die is easily clogged. If it exceeds, the removal of the solvent becomes difficult, the contact resistance between the catalyst layer and the gas diffusion layer increases, and the power generation performance may deteriorate.

The organic solvent preferably has a solubility parameter (δ) in the range of 7.5 to 13 (cal / mol) ^1/2 . If the solubility parameter of the organic solvent is outside the above range, the solubility of the protonic acid group-containing aromatic polymer is lowered, the coating of the polymer on the conductive filler becomes excessive, and the gas diffusion layer and the catalyst layer In some cases, the gas permeability may decrease.

Further, the organic solvent is, -O -, - OH, -CO -, - SO -, - SO 2 -, - COO
It is preferable to have at least one group selected from the group consisting of-and -CONR- (R is a hydrogen atom or a hydrocarbon group).

  Specific examples of the organic solvent include those exemplified as the organic solvent used in the catalyst paste composition, and may be used singly or in combination of two or more.

  The organic solvent is used in an amount of 50% to 99% by weight, preferably 70% to 95% by weight in the adhesive composition. By using the organic solvent in an amount within the above range, the adhesive composition becomes a paste and is suitable for handling, and gas permeability between the catalyst layer and the gas diffusion layer can be sufficiently secured.

  You may add a dispersing agent to the said adhesive composition further as needed. When a dispersant is added to the adhesive composition, the adhesive composition is excellent in dispersibility, storage stability and fluidity, and productivity during coating is improved.

  As said dispersing agent, the thing similar to what was illustrated as a dispersing agent which can be used for the said catalyst paste composition is mentioned, You may use it individually by 1 type, or may be used in combination of 2 or more type. The dispersant is preferably a surfactant having a basic group, more preferably an anionic or cationic surfactant, and still more preferably a surfactant having a molecular weight of 5,000 to 30,000. .

  In the adhesive composition, the content of the dispersant is 0 wt% to 10 wt%, preferably 0 wt% to 2 wt%. When the content of the dispersant is within the above range, an adhesive composition excellent in dispersibility, storage stability and fluidity can be obtained.

Although the preparation method of the said adhesive composition is not specifically limited, For example, it can prepare by mixing each said component by a predetermined ratio and knead | mixing by a conventionally well-known method.
As a method for applying the adhesive composition, a conventionally known method can be used, and examples thereof include brush coating, brush coating, bar coater coating, knife coater coating, doctor blade method, screen printing, and spray coating. .

  In addition, as a transfer substrate when an adhesive layer is once formed by applying on a transfer substrate, a polytetrafluoroethylene (PTFE) sheet, or a glass plate or metal plate whose surface is treated with a release agent Can be used.

As for the coating amount of the adhesive layer (the amount after drying), the weight per unit area of the coated surface is 0.01 to 10 mg / cm ² , preferably 0.01 to 1 mg / cm ² . When the coating amount is less than the above range, the binding strength by the adhesive layer is weak and the gas diffusion layer may be peeled off. On the other hand, when the coating amount exceeds the above range, there is a risk of increasing the contact resistance between the gas diffusion layer and the catalyst layer and reducing the gas permeability.

  Removal of the solvent after the application of the adhesive composition is performed at a drying temperature of 20 ° C. to 180 ° C., preferably 50 ° C. to 160 ° C., and a drying time of 5 minutes to 600 minutes, preferably 30 minutes to 400 minutes. If necessary, it can be removed by immersion in water. The water immersion temperature is 5 ° C to 120 ° C, preferably 15 ° C to 95 ° C, and the water immersion time is 1 minute to 72 hours, preferably 5 minutes to 48 hours.

[Example]
EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. The measurement of ion exchange capacity and molecular weight, as well as the production and performance evaluation of fuel cells were performed as follows.

(1) Ion exchange capacity The obtained polymer having a sulfonic acid group was sufficiently washed until the washing water became neutral to remove the remaining acid free. After drying, a predetermined amount was weighed, phenolphthalein dissolved in a THF / water mixed solvent was used as an indicator, and titration was performed using a standard solution of NaOH, and the ion exchange capacity was determined from the neutralization point.

(2) Molecular Weight The molecular weight of polyarylene having no sulfonic acid group was determined by GPC using polystyrene (THF) as a solvent and the molecular weight in terms of polystyrene. The molecular weight of polyarylene having a sulfonic acid group was determined by GPC using polystyrene as a molecular weight using N-methyl-2-pyrrolidone (NMP) to which lithium bromide and phosphoric acid were added as an eluent.

(3) Fabrication of fuel cell and evaluation of power generation Membrane-electrode assemblies fabricated in the following examples and comparative examples are sandwiched between two titanium current collectors, and a heater is further disposed on the outer side to provide an effective area of 25 cm ^2. The fuel cell was assembled.

The temperature of the produced fuel cell is maintained at 80 ° C., hydrogen and oxygen are supplied at a humidity of 100% RH at a back pressure of 0.15 MPa, and a load is applied at a constant current density of 1.0 A / cm ² with respect to the area of the electrode catalyst layer. The initial value of the cell voltage was measured after 100 hours (100 h) and after 500 hours (500 h).

Further, after the 500 hour power generation durability test, the fuel cell was disassembled, the membrane-electrode assembly was taken out, and the presence or absence of peeling of the gas diffusion layer was observed.
<Synthesis Example 1>
2,5-dichloro-4 ′-(4-phenoxyphenoxy) benzophenone 131.86 g (303 mmol), 4,4′-bis (4-chlorobenzoyl) diphenyl ether 84.99 g (190 mmol), sodium iodide 7.4 g ( 49 mmol), 7.4 g (11 mmol) of bis (triphenylphosphine) nickel dichloride, 29.8 g (113 mmol) of triphenylphosphine, and 49.4 g (760 mmol) of zinc were put into a three-necked flask equipped with a condenser and a three-way cock. It was attached to an oil bath at 70 ° C. After nitrogen substitution, 1,000 mL of N-methyl-2-pyrrolidone was added under a nitrogen atmosphere to initiate the polymerization reaction. After reacting for 20 hours, the reaction solution was diluted with 500 mL of N-methyl-2-pyrrolidone and poured into a large excess of hydrochloric acid / methanol solution (1/10) to precipitate a polymer. The product was purified by repeated washing and filtration, and after drying in vacuo, a white powder was obtained. The yield was 174.4 g, and the yield was 93%. The weight average molecular weight was 127,000.

  To 150 g of the obtained polymer, 1,500 mL of concentrated sulfuric acid was added and stirred, and a sulfonation reaction was performed at room temperature for 24 hours. The obtained reaction solution was poured into a large amount of pure water to precipitate a sulfonated polymer. The polymer was continuously washed with water until it became nearly neutral, and after filtration, the sulfonated polymer was recovered and vacuum-dried at 90 ° C. The yield of sulfonated polymer was 185.0 g. The ion exchange capacity of this polymer was 2.1 meq / g, and the weight average molecular weight was 189,000.

<Synthesis Example 2>
(1) Synthesis of hydrophobic unit (I) Into a 1 L three-necked flask equipped with a stirrer, thermometer, Dean-stark tube, nitrogen introduction tube and condenser tube, 48.8 g (284 mmol) of 2,6-dichlorobenzonitrile, Weighed 89.5 g (266 mmol) of 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane and 47.8 g (346 mmol) of potassium carbonate. After replacing the atmosphere in the flask with nitrogen, 346 mL of sulfolane and 173 mL of toluene were added and stirred, and the reaction solution was heated to reflux at 150 ° C. using an oil bath. Water produced by the reaction was trapped in a Dean-stark tube. After 3 hours, when almost no water was observed, toluene was removed from the Dean-stark tube out of the system. The reaction temperature was gradually raised to 200 ° C. and stirring was continued for 3 hours. Then, 9.2 g (53 mmol) of 2,6-dichlorobenzonitrile was added, and the reaction was further continued for 5 hours. The reaction solution was allowed to cool, and diluted with 100 mL of toluene. Inorganic salts insoluble in the reaction solution were filtered, and the filtrate was poured into 2 L of methanol to precipitate the product. The precipitated product was filtered and dried, dissolved in 250 mL of tetrahydrofuran, and poured into 2 L of methanol for reprecipitation. The precipitate was filtered and dried to obtain 109 g of the desired product as a white powder. The obtained compound had a number average molecular weight (Mn) by GPC of 9,500. It was confirmed that the obtained compound was an oligomer represented by the following formula (I).

(2) Synthesis of sulfonated polyarylene (II) In a 1 L three-necked flask equipped with a stirrer, a thermometer and a nitrogen introduction tube, 135.2 g (337 mmol) of neopentyl 3- (2,5-dichlorobenzoyl) benzenesulfonate, 48.7 g (5.1 mmol) of the hydrophobic unit of Mn 9,500 obtained in (1), 6.71 g (10.3 mmol) of bis (triphenylphosphine) nickel dichloride, 1.54 g (10.3 mmol) of sodium iodide ), 35.9 g (137 mmol) of triphenylphosphine and 53.7 g (821 mmol) of zinc were weighed and substituted with dry nitrogen. 430 mL of N, N-dimethylacetamide (DMAc) was added thereto, and stirring was continued for 3 hours while maintaining the reaction temperature at 80 ° C. Then, 730 mL of DMAc was added for dilution, and insoluble matters were filtered off.

  The obtained solution was put into a 2 L three-necked flask equipped with a stirrer, a thermometer, and a nitrogen introduction tube, heated and stirred at 115 ° C., and 44 g (506 mmol) of lithium bromide was added. After stirring for 7 hours, the reaction solution was poured into 5 L of acetone to precipitate the product. Next, the precipitate was washed with 1N hydrochloric acid and pure water in this order and then dried to obtain 122 g of the target polymer. The weight average molecular weight (Mw) of the obtained polymer was 135,000. The obtained polymer is presumed to be a sulfonated polyarylene represented by the following formula (II). The ion exchange capacity of the sulfonated polyarylene (II) was 2.3 meq / g.

<Synthesis Example 3>
(1) Synthesis of hydrophobic unit (III) 1,3-bis (4-chlorobenzoyl) benzene 17.8 g (50.0 mmol) was added to a 500 mL three-necked flask equipped with a stirring blade, a thermometer and a nitrogen introduction tube. , 2,2-bis (4-hydroxyphenyl) hexafluoropropane (15.1 g, 45.0 mmol), potassium carbonate (8.1 g, 58.5 mol), sulfolane (117 g), and toluene (40 g) were added at 130 ° C. under a nitrogen atmosphere. Stir. After removing water by azeotropy with toluene, toluene was removed from the system and stirred at 195 ° C. for 7 hours. The reaction solution was cooled to 100 ° C., 5.33 g (15.0 mmol) of 1,3-bis (4-chlorobenzoyl) benzene was added, and the mixture was again stirred at 195 ° C. for 3 hours. Diluted with toluene, and solid content was removed by Celite filtration. The filtrate was poured into a methanol / concentrated hydrochloric acid solution (methanol 2.0 L / concentrated hydrochloric acid 0.2 L) to coagulate the reaction product. The solid was filtered by suction filtration, and the obtained solid was washed with methanol and then air-dried. This was redissolved in tetrahydrofuran and poured into 3.0 L of methanol to solidify the reaction product. The solid was filtered by suction filtration, and the obtained solid was air-dried and further vacuum-dried to obtain 22.1 g of the desired hydrophobic unit (yield 75%). The product obtained by GPC (polystyrene conversion) had a number average molecular weight of 8,000 and a weight average molecular weight of 14,000. It was confirmed that the obtained compound was an oligomer represented by the following formula (III).

(2) Synthesis of sulfonated polyarylene (IV) In a 500 mL three-necked flask equipped with a stirring blade, a thermometer and a nitrogen inlet tube, 31.6 g (78 of neopentyl 3- (2,5-dichlorobenzoyl) benzenesulfonate was added. 0.7 mmol), 14.1 g (1.76 mmol) of the hydrophobic unit obtained in (1), 8.39 g (32.0 mmol) of triphenylphosphine, 12.6 g (192 mmol) of zinc, bis (triphenylphosphine) nickel Weighed 2.09 g (3.2 mmol) of dichloride and 0.36 g (2.4 mmol) of sodium iodide. The flask was placed in an oil bath heated to 40 ° C. and dried in vacuum for 2 hours. After the inside was purged with dry nitrogen several times, 100 mL of dehydrated dimethylacetamide was added to initiate polymerization. The polymerization was continued for 3 hours while controlling the reaction temperature not to exceed 90 ° C. After completion of the reaction, 360 g of dimethylacetamide was added for dilution, the insoluble matter was removed by celite filtration, and the solid content was concentrated to 12%.

  The obtained concentrated liquid was put into a 1 L three-necked flask equipped with a stirring blade, a thermometer, and a nitrogen introduction tube, 15.1 g (173 mmol) of lithium bromide was added, and the mixture was stirred at 120 ° C. for 7 hours. After completion of the reaction, the reaction solution was poured into 4 L of acetone to coagulate the reaction product. The solid was filtered by suction filtration, and the obtained solid was washed with methanol, then air-dried and further vacuum-dried to obtain 30.0 g of the desired polymer (yield 87%). The number average molecular weight of the product determined by GPC (polystyrene conversion) was 102,000, and the weight average molecular weight was 320,000. The obtained polymer is presumed to be a sulfonated polyarylene represented by the following formula (IV). The ion exchange capacity of the sulfonated polyarylene (IV) was 2.1 meq / g.

[Example 1]
In producing the membrane-electrode assembly, first, a polymer electrolyte membrane having catalyst layers on both sides was produced by the following method.

Place 50 g of zirconia balls ("YTZ balls" manufactured by Nikkato Co., Ltd.) 25 g in a 50 ml glass bottle, 1.51 g of platinum-supported carbon particles (Pt: 46 wt% supported, "TEC10E50E" manufactured by Tanaka Kikinzoku Co., Ltd.), distilled A mixture of 0.88 g of water, 3.23 g of a 15% N-methyl-2-pyrrolidone solution of the sulfonated polyarylene (II) obtained in Synthesis Example 2 and 12.47 g of N-methyl-2-pyrrolidone was obtained using a wave blower. After stirring for 10 minutes, 0.028 g of a dispersant (“DA234” manufactured by Enomoto Kasei Co., Ltd.) was added, and the mixture was further stirred for 30 minutes with a wafer blower to obtain a catalyst paste composition containing sulfonated polyarylene (II). .

The catalyst paste composition obtained by the above method was applied to both surfaces of a 50 μm-thick polymer electrolyte membrane made of the sulfonated polymer obtained in Synthesis Example 1 using a doctor blade, and at 120 ° C. for 1 hour. By heating and drying, one polymer electrolyte membrane having a catalyst layer with a platinum amount of 1.0 mg / cm ² on both sides was obtained.

Then, the adhesive layer was formed in the single side | surface of the carbon paper (product made from Toray) by which the water repellent process was carried out with the following method.
In a 50 ml glass bottle, 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.), 1.51 g of “Ketjen Black EC” manufactured by Lion, 0.88 g of distilled water, and the sulfone obtained in Synthesis Example 3 A mixture of 3.23 g of a 15% N-methyl-2-pyrrolidone solution of modified polyarylene (IV) and 12.47 g of N-methyl-2-pyrrolidone was stirred for 10 minutes with a wave blower, and then a dispersant (Enomoto Kasei Co., Ltd.). "DA234 made by
”) 0.028 g was added, and the mixture was further stirred for 30 minutes with a wafer blower to obtain an adhesive composition containing sulfonated polyarylene (IV).

The adhesive composition obtained by the above method is applied to one side of a water-repellent treated carbon paper (manufactured by Toray) using a doctor blade, and heated and dried at 120 ° C. for 1 hour to obtain a coating amount. ^Two gas diffusion layers having an adhesive layer on one side of 0.2 mg / cm ² were obtained.

Next, a gas diffusion layer is disposed between the catalyst layers formed on both surfaces of the polymer electrolyte membrane so that the adhesive layer surface is in contact, and hot press molding is performed at 160 ° C. for 15 minutes under a pressure of 100 kg / cm ^2. A membrane-electrode assembly was prepared. Table 1 shows the results of power generation evaluation.

[Example 2]
Instead of the sulfonated polyarylene (IV) obtained in Synthesis Example 3 as the sulfonated polyarylene in the adhesive composition, the sulfonated polyarylene obtained in Synthesis Example 2 same as the sulfonated polyarylene in the catalyst layer was used. A membrane-electrode assembly was produced in the same manner as in Example 1 except that arylene (II) was used. Table 1 shows the results of power generation evaluation.

[Comparative Example 1]
A membrane-electrode assembly was produced in the same manner as in Example 1 except that a gas diffusion layer that did not form an adhesive layer was used. Delamination of the gas diffusion layer was observed. Table 1 shows the results of power generation evaluation.

Claims (3)

A membrane-electrode having a catalyst layer containing a protonic acid group-containing aromatic polymer and carbon particles carrying a metal catalyst on both sides of a solid polymer electrolyte membrane, and having a gas diffusion layer on the catalyst layer A method for manufacturing a joined body, comprising:
Joining at least one catalyst layer and the gas diffusion layer with an adhesive layer containing a protonic acid group-containing aromatic polymer and a conductive filler interposed therebetween,
The protonic acid group-containing aromatic polymer contained in the adhesive layer is the same as the protonic acid group-containing aromatic polymer contained in the catalyst layer,
In the protonic acid group-containing aromatic polymer contained in the catalyst layer and the adhesive layer, the polymer segment (A) having an ion conductive component and the polymer segment (B) having no ion conductive component are covalently bonded. A method for producing a membrane-electrode assembly, which is a block copolymer. The protonic acid group-containing aromatic polymer contained in the catalyst layer is a sulfonated polyarylene having a structural unit represented by the following general formula (A) and a structural unit represented by the following general formula (B). The method for producing a membrane-electrode assembly according to claim 1, wherein:

[In Formula (A), Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _i — (i represents an integer of 1 to 10). Or -C (CF ₃ ) _2-
Z independently represents a direct bond, — (CH ₂ ) _j — (j represents an integer of 1 to 10), —C (CH ₃ ) ₂ —, —O— or —S—;
Ar is a fragrance having a substituent represented by —SO ₃ H, —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H (p represents an integer of 1 to 12). Indicates a group,
m shows the integer of 0-10, n shows the integer of 0-10, k shows the integer of 1-4. ]

[In Formula (B), A and D are each independently a direct bond, —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _i — (i is 1 an integer of _{~10), -. (CH 2} ) j - (j is an integer of _{1~10), -. CR '2} - (R' is an aliphatic hydrocarbon group, aromatic hydrocarbon group or A halogenated hydrocarbon group), a cyclohexylidene group, a fluorenylidene group, -O- or -S-
B independently represents an oxygen atom or a sulfur atom;
R ^{1 to} R ¹⁶ each independently represent a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group partially or wholly halogenated, an allyl group, an aryl group, a nitro group, or a nitrile group;
s and t each represent an integer of 0 to 4, and r represents 0 or an integer of 1 or more. ] Said adhesive layer, and the protonic acid group-containing aromatic polymer and a conductive filler, 5/95 to 60/40 weight ratio or claim 1, characterized in that it contains at (polymer / filler) 2 The manufacturing method of the membrane-electrode assembly as described in 1 above.