JP2006031970A - Proton conductive polymer electrolyte membrane, polymer electrolyte membrane-electrode assembly, manufacturing method for them, and fuel cell using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proton conductive polymer electrolyte membrane capable of maintaining proton conductivity and suppressing penetration of methanol as an electrolyte membrane for a fuel cell, a direct methanol fuel cell in particular, a polymer electrolyte membrane-electrode assembly using the high polymer electrolyte membrane, a manufacturing method for them, and a fuel cell using it. <P>SOLUTION: A polymer electrolyte membrane characterized by containing (A) a polymer having an acid-generating group, and (B) a compound having a hydroxyl group is used for the high polymer electrolyte membrane for the fuel cell. In addition, a polymer electrolyte membrane-electrode assembly composed of two electrodes and either one of high polymer electrolyte membranes disposed between the two electrodes is used for the polymer electrode membrane-electrode assembly for the fuel cell. Furthermore, these polymer electrolyte membrane and polymer electrolyte membrane-electrode assembly are used as the fuel cell. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polymer electrolyte membrane, in particular, a proton conductive polymer electrolyte membrane, a joined body of the polymer electrolyte membrane and an electrode, a production method thereof, and a fuel cell using the same.

A fuel cell is expected to be a next-generation power generation device that has high power generation efficiency and is excellent in environmental friendliness, and that can contribute to the solution of environmental problems and energy problems, which are currently major issues.
Among these fuel cells, polymer fuel cells are smaller and have higher output than any other system, and are the next generation as small-scale on-site, mobile (on-vehicle) and portable fuel cells. It is considered the main force.
At present, polymer fuel cells have not yet reached the stage of practical use, but the polymer electrolyte membranes of fuel cells that are used in trial production or in the test stage have a perfluoroalkylene group as the main skeleton and a portion of the polymer electrolyte membrane. “Nafion (R)”, “Flemion (R)” and the like are known as fluorine-based polymer electrolyte membranes having an ion exchange group such as a sulfonic acid group or a carboxylic acid group at the end of the fluorovinyl ether side chain.

However, in this polymer electrolyte membrane such as “Nafion (R)”, when the operation is performed at a temperature exceeding 100 ° C., the water content of the polymer electrolyte membrane is drastically lowered, and the softening of the polymer electrolyte membrane is remarkable. In particular, in the direct methanol fuel cell, which is expected for the future, when a fluorine-based proton conductive polymer material such as the conventional “Nafion (R)” is used as the electrolyte, It diffuses in the electrolyte membrane and reaches the cathode, where it causes a short circuit phenomenon (crossover) that directly reacts with the oxidant (O ₂ ) on the cathode catalyst, so that the battery performance is remarkably lowered, so that sufficient performance is achieved. There is a problem that it cannot be demonstrated. This methanol crossover becomes more prominent as the concentration of methanol, which is a fuel, is higher, and as the electrode becomes more active in catalytic action.
Further, as a material other than the fluorine-based proton conductive polymer material, a hydrocarbon-based proton conductive polymer material such as a sulfonated aromatic polyether ketone (Patent Document 1) has been studied as a polymer electrolyte membrane. This polymer electrolyte membrane can improve proton conductivity and methanol permeation resistance as compared with a polymer electrolyte membrane made of a fluorine-based proton conductive polymer material, but is still unsatisfactory for use as a polymer electrolyte membrane. It is enough. In order to realize higher proton conductivity and methanol permeation resistance, there is a method of using a polyimide having a specific proton acid group as an electrolyte membrane (Patent Document 2). This method is applied to an actual fuel cell. However, when the current density is increased, there is a drawback in that the output voltage drop increases.

JP-A-6-93114 JP 2003-338298 A

In view of the above circumstances, an object of the present invention is to provide a proton conductive polymer electrolyte membrane capable of suppressing methanol permeation while maintaining proton conductivity as an electrolyte membrane for a fuel cell, particularly a direct methanol fuel cell. It is an object of the present invention to provide a polymer electrolyte membrane-electrode assembly using a polymer electrolyte membrane, a production method thereof, and a fuel cell using the same.
Another object of the present invention is to provide an electrolyte membrane that has low swelling with respect to a solvent such as water and methanol, low methanol permeability, and high proton conductivity.

As a result of intensive studies, the present inventors have adopted a polymer electrolyte membrane comprising a polymer having an acid-generating group and a compound having a hydroxyl group as a polymer electrolyte membrane for a fuel cell. Thus, it has been found that an electrolyte membrane having low swelling with respect to liquids such as water and methanol, low methanol permeability, and high proton conductivity can be provided.
That is, the present invention relates to a polymer electrolyte membrane comprising (A) a polymer having an acid-generating group and (B) a compound having a hydroxyl group.
The present invention also relates to a polymer electrolyte membrane-electrode assembly comprising two electrodes and the polymer electrolyte membrane disposed between the two electrodes, and a method for producing the assembly.
Furthermore, the present invention relates to a fuel cell including the polymer electrolyte membrane-electrode assembly.

According to the present invention, it is possible to provide a polymer electrolyte membrane excellent in processability, durability and heat resistance in addition to suppressing methanol permeability while maintaining high proton conductivity.
Further, according to the present invention, it is possible to provide a fuel cell that can withstand operation at a high temperature, does not deteriorate the above characteristics even at a high temperature, and has good output characteristics.

Hereinafter, the present invention will be described in detail.
(1) Polymer electrolyte membrane The polymer electrolyte membrane of the present invention comprises (A) a polymer having an acid-generating group, (B) a compound having a hydroxyl group, optionally (C) another polymer, and (D) other Contains additives. Hereinafter, each component of (A)-(D), the manufacturing method of a polymer electrolyte membrane, etc. are demonstrated.

(1-1) (A) Polymer having acid-forming group
(1-1-1) (A) Structure of polymer having acid generating group (A) The polymer having an acid generating group used in the present invention is not particularly limited, and examples thereof include perfluorocarbon sulfonic acid resins and sulfonation. Polyester, Phosphonated polyester, Sulfonated polyamide, Phosphonated polyjamide, Sulfonated polyimide, Phosphonated polyimide, Sulfonated polyurethane, Phosphonated polyurethane, Sulfonated polysulfone, Phosphonated polysulfone, Sulfonated polyarylene ether sulfone, Phosphonated poly Arylene ether sulfone, sulfonated polyether ether ketone, phosphonated polyether ether ketone, sulfonated polyphenylene, phosphonated polyphenylene, sulfonated polyphenylene oxide, phosphonated polyphenylene ox De, sulfonated polyvinyl, phosphonated polyvinyl, sulfonated acrylate, phosphonated acrylate. These can be used alone or in combination of two or more. Among these, sulfonated polyarylene ether sulfone and / or phosphonated polyarylene ether sulfone are preferable from the viewpoint of heat resistance and proton conductivity.

A preferred structure of the polymer (A) having an acid generating group used in the present invention includes a structure containing a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2). .
Formula (1) -Ar ₁ -O-
[In the formula (1), Ar ₁ represents a bond unit represented by at least one formula selected from the group consisting of the following formulas (3), (4) and (5). ]
Equation ₍₂₎ -Ar 2 -O-
[In the formula (2), Ar ₂ represents a bond unit represented by at least one formula selected from the group consisting of the following formulas (6), (7), (8) and (9). ]

式（３）において、Ａは直接結合、−Ｏ−、−Ｓ−、−Ｓ（Ｏ）−、−Ｓ（Ｏ）₂−、−Ｃ（Ｏ）−、−Ｐ（Ｏ）（Ｃ₆Ｈ₅）−、−Ｃ（ＣＨ₃）₂−、−Ｃ（ＣＦ₃）₂−、

または炭素数１〜６のアルキレン基を示す。Ｂ、Ｃ、Ｄ、Ｅはそれぞれ独立に水素、炭素数１〜６の脂肪族基、フェニル基、ニトロ基、塩素、臭素、及びヨウ素からなる群より選択される基であり、ただし、Ｂ、Ｃ、Ｄ、Ｅのうち少なくとも２種は水素よりなる。 Hereinafter, the bond units represented by formulas (3) to (9) will be described in detail.
Formula (3):

In the formula (3), A is a direct bond, —O—, —S—, —S (O) —, —S (O) ₂ —, —C (O) —, —P (O) (C ₆ H _{5) -, - C (CH} 3) 2 -, - C (CF 3) 2 -,

Or an alkylene group having 1 to 6 carbon atoms; B, C, D, and E are each independently a group selected from the group consisting of hydrogen, an aliphatic group having 1 to 6 carbon atoms, a phenyl group, a nitro group, chlorine, bromine, and iodine, provided that B, At least two of C, D, and E are made of hydrogen.

Formula (3) may select any structure formed by A to E.
As an example of the above equation (3),
_{-C 6 H 4 -SO 2 -C 6} H 4 -,
_{-C 6 H 4 -CO-C 6} H 4 -,
_{-C 6 H 4 -PO (C 6} H 5) -C 6 H 4 -,
_{-C 6 H 4 -C (CF 3} ) 2 -C 6 H 4 -,
_{-C 6 H 4 -C (CH 3} ) 2 -C 6 H 4 -,
_{-C 6 H 4 -C (C 6} H 4) 2 -C 6 H 4 -,
_{-C 6 H 4 -O-C 6} H 4 -,
_{-C 6 H 4 -C 6 H 4} -,
_{-C 6 H 4 -S-C 6} H 4 -,
Etc.

Preferably,
_{-C 6 H 4 -SO 2 -C 6} H 4 -,
_{-C 6 H 4 -CO-C 6} H 4 -,
_{-C 6 H 4 -PO (C 6} H 5) -C 6 H 4 -,
_{-C 6 H 4 -O-C 6} H 4 -,
_{-C 6 H 4 -C 6 H 4} -,
_{-C 6 H 4 -S-C 6} H 4 -,
_{-C 6 H 4 -C (C 6} H 4) 2 -C 6 H 4 -,
Etc.

Particularly preferably,
_{-C 6 H 4 -SO 2 -C 6} H 4 -,
_{-C 6 H 4 -CO-C 6} H 4 -,
_{-C 6 H 4 -PO (C 6} H 5) -C 6 H 4 -,
_{-C 6 H 4 -O-C 6} H 4 -,
_{-C 6 H 4 -C 6 H 4} -,
_{-C 6 H 4 -C (C 6} H 4) 2 -C 6 H 4 -,
Etc.

式（４）において、Ｆは直接結合、−Ｏ−、−Ｓ−、−Ｓ（Ｏ）−、−Ｓ（Ｏ）₂−、−Ｃ（Ｏ）−、−Ｐ（Ｏ）（Ｃ₆Ｈ₅）−、−Ｃ（ＣＨ₃）₂−、−Ｃ（ＣＦ₃）₂−、

または炭素数１〜６のアルキレン基を示す。 Formula (4):

In the formula (4), F represents a direct bond, —O—, —S—, —S (O) —, —S (O) ₂ —, —C (O) —, —P (O) (C ₆ H _{5) -, - C (CH} 3) 2 -, - C (CF 3) 2 -,

Or an alkylene group having 1 to 6 carbon atoms;

等が挙げられる。 Equation (4) may select any structure formed by F.
As an example of equation (4),

Etc.

である。
式（５）の例としては、

等が挙げられる。 Formula (5):

It is.
As an example of equation (5),

Etc.

式（６）において、Ｌは直接結合、−Ｏ−、−Ｓ−、−Ｓ（Ｏ）−、−Ｓ（Ｏ）₂−、−Ｃ（Ｏ）−、−Ｐ（Ｏ）（Ｃ₆Ｈ₅）−、−Ｃ（ＣＨ₃）₂−、−Ｃ（ＣＦ₃）₂−、

または炭素数１〜６のアルキレン基を示す。Ｎは水素、炭素１〜６の脂肪族基、フェニル基、ニトロ基、塩素、臭素、及びヨウ素からなる群より選択される基であり、ＭはＳＯ₃Ｈ、ＣＯＯＨ、及びＰＯ₃Ｈ₂からなる群より選択される酸基を示す。ｎは１から４の置換基数を表わし、ｍは４−ｎの置換基数を表わす。 Formula (6):

In the formula (6), L represents a direct bond, —O—, —S—, —S (O) —, —S (O) ₂ —, —C (O) —, —P (O) (C ₆ H _{5) -, - C (CH} 3) 2 -, - C (CF 3) 2 -,

Or an alkylene group having 1 to 6 carbon atoms; N is a group selected from the group consisting of hydrogen, an aliphatic group having 1 to 6 carbon atoms, a phenyl group, a nitro group, chlorine, bromine, and iodine, and M is a group consisting of SO ₃ H, COOH, and PO ₃ H _2. An acid group selected from the group consisting of n represents the number of 1 to 4 substituents, and m represents the number of 4-n substituents.

As an example of equation (6),
_{-C 6 H 3 (SO 3 H} ) -SO 2 -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -CO-C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -PO (C 6 H 5) -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -O-C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -S-C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -C (C 6 H 4) 2 -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -C (CF 3) 2 -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -C (CH 3) 2 -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (PO 3 H} 2) -SO 2 -C 6 H 3 (PO 3 H 2) -,
_{-C 6 H 3 (PO 3 H} 2) -CO-C 6 H 3 (PO 3 H 2) -,
_{-C 6 H 3 (PO 3 H} 2) -C 6 H 3 (PO 3 H 2) -,
_{-C 6 H 3 (PO 3 H} 2) -PO (C 6 H 5) -C 6 H 3 (PO 3 H 2) -,
_{-C 6 H 3 (PO 3 H} 2) -O-C 6 H 3 (PO 3 H 2) -,
_{-C 6 H 3 (PO 3 H} 2) -S-C 6 H 3 (PO 3 H 2) -,
_{-C 6 H 3 (PO 3 H} 2) -C (C 6 H 4) 2 -C 6 H 3 (PO 3 H 2) -,
_{-C 6 H 3 (PO 3 H} 2) -C (CF 3) 2 -C 6 H 3 (PO 3 H 2) -, or _{-C 6 H 3 (PO 3 H} 2) -C (CH 3) 2 -C ₆ H ₃ (PO ₃ H ₂ )-
Etc.

Preferably,
_{-C 6 H 3 (SO 3 H} ) -SO 2 -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -CO-C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -PO (C 6 H 5) -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -O-C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -S-C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -C (C 6 H 4) 2 -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -C (CF 3) 2 -C 6 H 3 (SO 3 H) - or _{-C 6 H 3 (SO 3 H} ) -C (CH 3) 2 -C 6, H ₃ (SO ₃ H) −
Etc.

Particularly preferably,
_{-C 6 H 3 (SO 3 H} ) -SO 2 -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -CO-C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -PO (C 6 H 5) -C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -O-C 6 H 3 (SO 3 H) -,
_{-C 6 H 3 (SO 3 H} ) -S-C 6 H 3 (SO 3 H) -, or _{-C 6 H 3 (SO 3 H} ) -C (C 6 H 4) 2 -C 6 H 3 ( SO ₃ H) -,
Etc.

式（７）において、Ｘは直接結合、−Ｏ−、−Ｓ−、−Ｓ（Ｏ）−、−Ｓ（Ｏ）₂−、−Ｃ（Ｏ）−、−Ｐ（Ｏ）（Ｃ₆Ｈ₅）−、−Ｃ（ＣＨ₃）₂−、−Ｃ（ＣＦ₃）₂−、

または炭素数１〜６のアルキレン基を示す。Ｐは水素、炭素数１〜６の脂肪族基、フェニル基、ニトロ基、塩素、臭素、及びヨウ素からなる群より選択される基であり、ＱはＳＯ₃Ｈ、ＣＯＯＨ、及びＰＯ₃Ｈ₂からなる群より選択される酸基を示す。ｎは１から４の置換基数を表わし、ｍは４−ｎの置換基数を表わす。 Formula (7):

In the formula (7), X represents a direct bond, —O—, —S—, —S (O) —, —S (O) ₂ —, —C (O) —, —P (O) (C ₆ H _{5) -, - C (CH} 3) 2 -, - C (CF 3) 2 -,

Or an alkylene group having 1 to 6 carbon atoms; P is a group selected from the group consisting of hydrogen, an aliphatic group having 1 to 6 carbon atoms, phenyl group, nitro group, chlorine, bromine, and iodine, and Q is SO ₃ H, COOH, and PO ₃ H _2. An acid group selected from the group consisting of n represents the number of 1 to 4 substituents, and m represents the number of 4-n substituents.

等が挙げられる。 As an example of the above equation (7),

Etc.

等が挙げられる。 Preferably,

Etc.

式（８）において、Ｙは直接結合、−Ｏ−、−Ｓ−、−Ｓ（Ｏ）−、−Ｓ（Ｏ）₂−、−Ｃ（Ｏ）−、−Ｐ（Ｏ）（Ｃ₆Ｈ_5）−、−Ｃ（ＣＨ₃）₂−、−Ｃ（ＣＦ₃）₂−、

または炭素数１〜６のアルキレン基を示す。Ｓは水素、炭素数１〜６の脂肪族基、フェニル基、ニトロ基、塩素、臭素、及びヨウ素からなる群より選択される基であり、ＴはＳＯ₃Ｈ、ＣＯＯＨ、及びＰＯ₃Ｈ₂からなる群より選択される酸基を示す。ｎは１から４の置換基数を表わし、ｍは４−ｎの置換基数を表わす。 Formula (8):

In the formula (8), Y represents a direct bond, —O—, —S—, —S (O) —, —S (O) ₂ —, —C (O) —, —P (O) (C ₆ H _{5) -, - C (CH} 3) 2 -, - C (CF 3) 2 -,

Or an alkylene group having 1 to 6 carbon atoms; S is a group selected from the group consisting of hydrogen, an aliphatic group having 1 to 6 carbon atoms, a phenyl group, a nitro group, chlorine, bromine, and iodine, and T is SO ₃ H, COOH, and PO ₃ H _2. An acid group selected from the group consisting of n represents the number of 1 to 4 substituents, and m represents the number of 4-n substituents.

等が挙げられる。 As an example of equation (8),

Etc.

等が挙げられる。 Preferably,

Etc.

式（９）において、Ｕは水素または炭素数１〜６の脂肪族基、フェニル基、ニトロ基、塩素、臭素、及びヨウ素からなる群より選択される基であり、ＶはＳＯ₃Ｈ、ＣＯＯＨ、及びＰＯ₃Ｈ₂からなる群より選択される酸基を示す。ｎは１から４の置換基数を表わし、ｍは４−ｎの置換基数を表わす。 Formula (9):

In the formula (9), U is hydrogen or a group selected from the group consisting of an aliphatic group having 1 to 6 carbon atoms, a phenyl group, a nitro group, chlorine, bromine, and iodine, and V is SO ₃ H, COOH. And an acid group selected from the group consisting of PO ₃ H ₂ . n represents the number of 1 to 4 substituents, and m represents the number of 4-n substituents.

等が挙げられる。 As an example of the above equation (9),

Etc.

等が挙げられる。 Preferably,

Etc.

The structure of the bonding unit Ar ₁ contained in the polymer having an acid generating group (A) of the present invention is not necessarily limited to one type, and Ar ₁ having two or more types of structures is contained in the same compound. May be. Similarly, the structure of the bonding unit Ar ₂ contained in the polymer (A) having an acid-generating group of the present invention is not necessarily limited to one type, and Ar ₂ having two or more types of structures is the same compound It may be contained in.
Examples of the precursor of Ar ₁ in the formula (1) include 4,4′-dichlorodiphenylsulfone, 4,4′-difluorodiphenylsulfone, 4,4′-difluorobenzophenone, 1,3-dichloronaphthalene, 1, 3-difluoronaphthalene, 1,5-dichloronaphthalene, 1,5-difluoronaphthalene, halogen compounds such as difluoro or dichloro compounds of quinoline derivatives represented by formula (4), 4,4′-biphenol, bis (4- Hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) ) Butane, 3,3-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxy-3, -Dimethylphenyl) propane, bis (4-hydroxy-3,5-dimethylphenyl) methane, bis (4-hydroxy-2,5-dimethylphenyl) methane, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxy Diphenyl ether, 4,4′-dihydroxydiphenyl thioether, 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxybenzophenone, 1,3-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, quinoline derivatives represented by formula (4) And hydroxy compounds such as dihydroxy compounds.

Examples of the precursor of Ar ₂ in formula (2) include sulfonic acid group-containing 4,4′-dichlorodiphenyl sulfone, sulfonic acid group-containing 4,4′-difluorodiphenyl sulfone, sulfonic acid group-containing 4,4′- Dichlorobenzophenone, sulfonic acid group-containing 4,4′-difluorobenzophenone, sulfonic acid group-containing 1,3-dichloronaphthalene, sulfonic acid group-containing 1,3-difluoronaphthalene, sulfonic acid group-containing 1,5-dichloronaphthalene, sulfonic acid Group-containing 1,5-difluoronaphthalene, sulfonic acid group-containing halogen compounds such as difluoro or dichloro compounds of sulfonic acid group-containing quinoline derivatives represented by formula (7) or (8), sulfonic acid group-containing 4,4′-dihydroxybiphenyl , Sulfonic acid group-containing 4,4′-dihydroxydiphenyl ether, sulfone Group-containing 4,4′-dihydroxydiphenylthioether, sulfonic acid group-containing 4,4′-dihydroxydiphenylsulfone, sulfonic acid group-containing 4,4′-dihydroxybenzophenone, sulfonic acid group-containing 1,3-dihydroxynaphthalene, sulfonic acid group And sulfonic acid group-containing dihydroxy compounds such as dihydroxy compounds of sulfonic acid group-containing quinoline derivatives represented by formula (7) or formula (8).

In the polymer having one (A) acid-generating group of the present invention, the chemical structure of the repeating unit represented by the formula (1) may be different for each repeating unit. The same applies to the repeating unit represented by the formula (2). The repeating unit represented by the formula (1) and the repeating unit represented by the formula (2) may be bonded in the form of random copolymerization or may be bonded in the form of block copolymerization. .
Furthermore, other repeating units may be included between the repeating units represented by the formulas (1) and (2).

  Examples of the repeating unit other than the repeating unit represented by formula (1) or formula (2) include alkylene ethers such as ethylene oxide, propylene oxide, and tetramethylene oxide, perfluoroalkylene ethers, aromatic imides, amides, oxazoles, and thiazoles. There are aromatic ethers having bonds such as, heterocycle-containing aromatic ethers such as thiophene and pyrrole, and aromatic sulfides.

  The polymer (A) having an acid-generating group of the present invention has a total α of the number of moles of repeating units represented by the above formula (2) and the number of moles of repeating units represented by the formulas (1) and (2). It is preferable that the total β satisfies the relationship of 0.01 ≦ α / β ≦ 1. This is because when a polymer electrolyte membrane containing a repeating unit other than the repeating units represented by the formulas (1) and (2) in the ratio within the above range is produced, only the repeating units (1) and (2) are used. This is because good proton conductivity comparable to that obtained when a polymer electrolyte membrane is produced from the above is obtained. From the viewpoint of proton conductivity and durability, the relational expression is preferably 0.1 ≦ α / β ≦ 0.8, and preferably 0.2 ≦ α / β ≦ 0.6. Is particularly preferred. When α / β is 0.01 or more, sufficient proton conductivity can be maintained when a polymer electrolyte membrane is obtained while maintaining sufficient durability.

(1-1-2) (A) Preparation of polymer having acid-forming group The method for preparing the polymer (A) having an acid-generating group of the present invention is not particularly limited. Or a method of polymerizing the acid-forming group-containing monomer by introducing an acid-generating group into the monomer to obtain an acid-generating group-containing monomer.
(1-1-2-1) Hydrocarbon polymer The hydrocarbon polymer of the present invention includes polyether ketone, polysulfide, polyphosphazene, polyphenylene, polybenzimidazole, polyethersulfone, polyphenylene oxide, polycarbonate, polyurethane, polyamide. , Polyimide, polyurea, polysulfone, polysulfonate, polybenzoxazole, polybenzothiazole, polythiazole, polyphenylquinoxaline, polyquinoline, polysiloxane, polytriazine, polydiene, polypyridine, polypyrimidine, polyoxathiazole, polytetrazapyrene, Polyoxazole, polyvinyl pyridine, polyvinyl imidazole, polypyrrolidone, polyacrylate derivatives, polymethacrylate derivatives, polystyrene derivatives, etc. And the like. Preferably, polyether ketone, polysulfide, polyphosphazene, polyphenylene, polybenzimidazole, polyethersulfone, polyphenylene oxide, polycarbonate, polyurethane, polyamide, polyimide, polyurea, polysulfone, polysulfonate, polybenzoxazole, polybenzothiazole, poly Examples thereof include phenylquinoxaline, polyquinoline, polytriazine, polydiene, polypyridine, polyoxathiazole, polyacrylate derivative, polymethacrylate derivative, and polystyrene derivative. Particularly preferred are polyether ketone, polysulfide, polyphosphazene, polyphenylene, polybenzimidazole, polyethersulfone, polyphenylene oxide, polycarbonate, polyamide, polyimide, polyurea, polysulfone, polysulfonate, polybenzoxazole, polybenzothiazole, polyphenyl. Examples include quinoxaline, polyquinoline, polytriazine, polydiene, polyacrylate derivative, polymethacrylate derivative, and polystyrene derivative. Among these, a polymer containing no fluorine is preferable from the viewpoint of environmental adaptability. In addition to fluorine-free polymers, fluorine-based polymers such as Nafion (R) and Flemion (R) can also be used.

(1-1-2-2) Monomer Examples of the monomer into which the acid-generating group is introduced include monomers used for preparing hydrocarbon-based polymers. For example, 4,4′-dihydroxydiphenyl ether, styrene, (meth) acrylonitrile, 9,9′-bis (4-hydroxyphenyl) fluorene, 2,7-dihydroxynaphthalene and the like can be mentioned.
(1-1-2-3) Acid-generating group Examples of the acid-generating group introduced into the hydrocarbon polymer and the monomer include functional groups that readily release protons. For example, sulfonic acid group (—SO ₃ H), carboxylic acid group (—COOH), phosphoric acid group (—PO ₃ H ₂ ), alkyl sulfonic acid group (— (CH ₂ ) _n SO ₃ H), alkyl carboxylic acid At least one selected from the group consisting of a group (— (CH ₂ ) _n COOH), an alkylphosphonic acid group (— (CH ₂ ) _n PO ₃ H ₂ ), and a phenolic hydroxyl group (—Ph—OH) Those included above are preferred (n is, for example, 1 to 10, preferably 1 to 5, for example). A part of the sulfonic acid group, carboxylic acid group, and phosphoric acid group may be substituted with an alkyl group, sodium, potassium, calcium, or the like. The alkyl group and alkylene group contained in the acid-generating group may contain 1 to 10, preferably 1 to 5 carbon atoms.

(1-1-2-4) Introduction of acid-generating group In order to introduce the acid-generating group such as sulfonic acid group, carboxylic acid group and phenolic hydroxyl group into the hydrocarbon-based polymer or monomer, there are various known ones. A functional group introduction reaction can be used. For example, when introducing a sulfonic acid group, a sulfonating agent is used. The sulfonating agent is not particularly limited, but for example, concentrated sulfuric acid, fuming sulfuric acid, chlorosulfuric acid, anhydrous sulfuric acid complex, etc. can be suitably used (because it is necessary to define the sulfonating agent) , “The sulfonic acid group introduction method can be introduced using…”, and this description was not adopted.) In addition, when a carboxylic acid group is introduced, an oxidation reaction, a hydrolysis reaction of a carboxylic acid derivative, a transfer reaction, or the like can be used. In the case of introducing a phenolic hydroxyl group, a substitution reaction such as halogen, a reduction reaction such as quinone, a hydrocarbon oxidation reaction, or the like can be used.
In particular, the acid-generating group is introduced into the aromatic ring represented by formula (6) and / or (7) and / or (8) and / or (9).

  Among them, as the sulfonating agent, the sulfonating agent described in Japanese Patent No. 2884189, namely 1,3,5-trimethylbenzene-2-sulfonic acid, 1,3,5-trimethylbenzene-2,4 -Disulfonic acid, 1,2,4-trimethylbenzene-5-sulfonic acid, 1,2,4-trimethylbenzene-3-sulfonic acid, 1,2,3-trimethylbenzene-4-sulfonic acid, 1,2, 3,4-tetramethylbenzene-5-sulfonic acid, 1,2,3,5-tetramethylbenzene-4-sulfonic acid, 1,2,4,5-tetramethylbenzene-3-sulfonic acid, 1,2 , 4,5-tetramethylbenzene-3,6-disulfonic acid, 1,2,3,4,5-pentamethylbenzene-6-sulfonic acid, 1,3,5-triethylbenzene-2-sulfone 1-ethyl-3,5-dimethylbenzene-2-sulfonic acid, 1-ethyl-3,5-dimethylbenzene-4-sulfonic acid, 1-ethyl-3,4-dimethylbenzene-6-sulfonic acid, 1 -Ethyl-2,5-dimethylbenzene-3-sulfonic acid, 1,2,3,4-tetraethylbenzene-5-sulfonic acid, 1,2,4,5-tetraethylbenzene-3-sulfonic acid, 1,2 , 3,4,5-pentaethylbenzene-6-sulfonic acid, 1,3,5-triisopropylbenzene-2-sulfonic acid, 1-propyl-3,5-dimethylbenzene-4-sulfonic acid, and salts thereof Etc. can also be used.

  Among the above sulfonating agents, compounds in which a lower alkyl is substituted at both ortho positions of the sulfonic acid group, such as 1,3,5-trimethylbenzene-2-sulfonic acid, 1,2,4,5-tetra Methylbenzene-3-sulfonic acid, 1,2,3,5-tetramethylbenzene-4-sulfonic acid, 1,2,3,4,5-pentamethylbenzene-6-sulfonic acid, 1,3,5- Trimethylbenzene-2,4-disulfonic acid, 1,3,5-toluethylbenzene-2-sulfonic acid, and salts thereof are preferable. Further, 1,3,5-trimethylbenzene-2-sulfonic acid and these salts are preferable. And a salt of bis (4-chlorophenyl) sulfone and 4,4′-dihydroxy-3,3′-disulfonic acid diphenylsulfone sodium salt.

  When the sulfonic acid group is introduced into the hydrocarbon-based polymer, the sulfonating agent is added in an amount of, for example, 1 to 20000 parts by mass, preferably 5 to 10000 parts by mass with respect to 100 parts by mass of the polymer. is there. If the addition amount of the sulfonating agent is 1 part by mass or more, the sulfonic acid group is sufficiently introduced. If the addition amount of the sulfonating agent is 20000 parts by mass or less, the treatment of the sulfonating agent after the reaction is performed. Is preferable. Moreover, when introduce | transducing a sulfonic acid group into a monomer, it is appropriate to add a sulfonating agent in 30-5000 mass parts with respect to 100 mass parts of monomers, Preferably it is 50-2000 mass parts. When the addition amount of the sulfonating agent is 30 parts by mass or more, the introduction of the sulfonic acid group is sufficiently performed. When the addition amount of the sulfonating agent is 5000 parts by mass or less, the treatment of the sulfonating agent after the reaction is performed. Since it becomes easy, it is preferable.

As a method for introducing a sulfonic acid group into a hydrocarbon-based polymer or monomer, a sulfonating agent can be used and reaction conditions corresponding to the compound structure can be selected.
For example, by reacting a hydrocarbon-based polymer or monomer with a sulfonating agent in the presence of a catalyst in a reaction temperature range of −20 to 150 ° C. and a reaction time of 0.5 to 50 hours, Can be introduced. If the reaction temperature is −20 ° C. or higher, the sulfonation reaction proceeds rapidly, and if the reaction temperature is 150 ° C. or lower, it is preferable because a sulfonic acid group can be introduced only into a specific aromatic ring.
Here, as the catalyst, alkali catalysts such as potassium carbonate, calcium carbonate and cesium carbonate, and metal halides such as cesium fluoride can be used. The catalyst amount can be 0.1 to 100 times the total number of moles of monomers to be reacted.

The introduction of the acid generating group may be performed in a solvent such as water and an organic solvent. The organic solvent is not particularly limited, and any conventionally known organic solvent can be used as long as it does not adversely affect the introduction of the acid generating group.
Specific examples include halogenated aliphatic hydrocarbons such as N-methyl-2-pyrrolidone, chloroform, dichloromethane, 1,2-dichloroethane, trichloroethane, tetrachloroethane, trichloroethylene, and tetrachloroethylene, and halogenations such as dichlorobenzene and trichlorobenzene. Aromatic hydrocarbons, nitro compounds such as nitromethane and nitrobenzene, alkylbenzenes such as trimethylbenzene, tributylbenzene, tetramethylbenzene and pentamethylbenzene, heterocyclic compounds such as sulfolane, octane, decane, cyclohexane and toluene Straight chain, branched chain or cyclic aliphatic saturated hydrocarbons.
These solvents may be used alone or in combination of two or more. Although the usage-amount of a solvent is selected suitably, it is preferable to exist in the range of 100-2,000 mass parts normally with respect to 100 mass parts of reagents, such as a sulfonating agent. When the amount of the organic solvent is 100 parts by mass or more, the sulfonation reaction can be progressed uniformly. When the amount of the organic solvent is 2,000 parts by mass or less, the organic solvent and the reagent after the reaction are separated. It is preferable because the solvent can be easily recovered.

Conventionally known purification methods can be suitably used as a method for purifying the obtained hydrocarbon-based polymer having an acid-generating group or an acid-generating group-containing monomer. For example, when the obtained polymer or monomer having an acid-generating group is in a solid state, the obtained polymer or monomer can be filtered, washed with a solvent such as water or an organic solvent, and dried to be purified. it can. In addition, when the obtained polymer or monomer is oily, when the oily substance and the solvent are separated into two phases, the solvent is separated, and if dissolved in the solvent, the solvent is evaporated. By removing it, it can be purified.
Alternatively, water is added to the reaction liquid containing the hydrocarbon-based polymer having an acid-generating group of the present invention or a monomer having an acid-generating group, and if necessary, an alkali component is added and dissolved to form an organic solvent phase and an aqueous phase. After the separation, a precipitate can be obtained from the aqueous phase by a method such as acid precipitation or salting out, and the obtained precipitate can be collected by filtration, washed with an organic solvent and dried.
In addition, when the acid-generating group is introduced only with a sulfonating agent such as concentrated sulfuric acid, the reaction solution containing the hydrocarbon-based polymer having the acid-generating group or the monomer having the acid-generating group of the present invention is poured into water. It is also effective to obtain a precipitate by collecting the precipitate and obtain a purified product.

(1-1-2-5) Polymerization of a hydrocarbon polymer or a polymer having an acid-generating group The polymerization method of a hydrocarbon-based polymer or the method of polymerizing a polymer having an acid-generating group from a monomer having an acid-generating group Known polymerization methods such as polymerization, addition polymerization, radical polymerization, and ring-opening polymerization can be used. Although superposition | polymerization temperature is based also on the superposition | polymerization method, it is 0-350 degreeC, for example, Preferably it is 40-260 degreeC. The polymerization time is, for example, 2 to 500 hours although it depends on the polymerization method.
Examples of the monomer used for the polymerization include a monomer having two or more functional groups capable of substitution reaction and a monomer having two or more functional groups capable of reacting with the monomer. Specifically, for example, the same monomer as that into which the acid-generating group is introduced can be used.
Monomers having two or more functional groups capable of substitution reaction are dihalongen, trihalogen, and tetrahalogenated compounds. Examples of halogen include fluorine, chlorine, bromine, and iodine. These halogenated compounds may be the same or different types of halogen compounds.
Examples of the monomer having two or more functional groups capable of reacting with the halogen compound monomer include dihydroxy, trihydroxy, tetrahydroxy compound, dithiophenol, trithiophenol, tetrathiophenol compound, diamino, triamino, and tetraamino compound. , Dimonosubstituted amino, trimonosubstituted amino, tetramonosubstituted amino and the like. The monomers capable of reacting with these halogen compounds may be the same or different types of compounds.

The polymerization of the hydrocarbon-based polymer or the polymer having an acid-generating group of the present invention can be performed in a solvent in the presence of a catalyst.
As the catalyst, alkali catalysts such as potassium carbonate, calcium carbonate and cesium carbonate and metal halides such as cesium fluoride can be used. The catalyst amount can be 0.1 to 100 times the total number of moles of monomers to be reacted.
Suitable reaction solvents include aprotic polar solvents such as N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone and hexamethylphosphonamide, and alcohols such as methanol and ethanol. However, the present invention is not limited to these. A plurality of these solvents may be used as a mixture within a possible range. The amount of the solvent can be used in a range of 0.01 to 2 times the total mass of the monomer to be reacted and the catalyst.

The number average molecular weight of the obtained hydrocarbon-based polymer or polymer having an acid-generating group is, for example, 1,000 to 1,000,000, preferably 5,000 to 500,000, more preferably 10,000 to 100. 000 is suitable.
A number average molecular weight of 1,000 or more is preferable because sufficient strength of a hydrocarbon polymer having an acid-generating group and a polymer electrolyte membrane obtained from the polymer can be obtained. Moreover, since it will not become difficult if it is 1,000,000 or less, it is preferable.

(1-2) (B) Compound having a hydroxyl group (B) The compound having a hydroxyl group is not particularly limited, but (A) an acid generating group of a polymer having an acid generating group and (B) a compound having a hydroxyl group. Any material can be used as long as the hydroxyl group can be bonded to form a crosslink. (B) The hydroxyl group in the compound having a hydroxyl group is bonded to a part of the acid generating group by, for example, a hydrogen bond, an ester bond, etc., and (A) the polymer having the acid generating group is crosslinked and pseudo-crosslinked. Constitute. As described above, (A) the polymer having an acid-generating group forms a cross-link through a part of the acid-generating group, so that (A) the proton-conducting polymer of the acid-generating group is maintained and methanol permeation is maintained. Sex can be suppressed.
Therefore, the compound (B) having a hydroxyl group is preferably a compound having at least two hydroxyl groups.
(B) Specific examples of the compound having a hydroxyl group include celluloses such as polyvinyl alcohol, methylcellulose, nitrocellulose, cellulose acetate, and cellulose acetate butyrate, organic polymers such as phenolic resin and phenolic borac resin, and smectite. Inorganic compounds can be mentioned. The polyvinyl alcohol may be a block or random copolymer in which other components are partially copolymerized, or a polymer or fine particles cross-linked by reacting with other components. Among the organic polymers, polyvinyl alcohol and copolymers thereof are preferable from the viewpoint of methanol blocking properties.
Examples of the smectite include bentonite, montmorillonite, and saponite. These inorganic compounds may be treated with an aliphatic amine compound, polyoxazoline or the like in order to enhance dispersibility.

  The content of the component (A) in the present invention is, for example, preferably 30 to 99% by mass and more preferably 40 to 95% by mass with respect to the total amount of the components (A) and (B). Preferably, it is more preferable to set it as 50-90 mass%. If this content is 30% by mass or more, good proton conductivity can be maintained, and if it is 99% by mass or less, methanol permeability can be sufficiently improved.

The mass average molecular weight when the compound having a hydroxyl group (B) is an organic polymer is not particularly limited, but is preferably in the range of 500 to 2,000,000, and preferably 1,000 to 1,000,000. A range is more preferable. If the mass average molecular weight is 500 or more, the methanol permeability is sufficiently improved, and if it is 1,000,000 or less, the processability is not impaired, which is preferable.
When the (B) hydroxyl group-containing compound is a fine particle, the average particle size is not particularly limited, but is, for example, 0.01 to 10 μm, preferably 0.01 to 1 μm.

(1-3) (C) Other polymers The polymer electrolyte membrane of the present invention is not limited to (A) the polymer having an acid-generating group of the present invention. It may contain a polymer.
Other polymers include, for example, general-purpose resins such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), ABS resin and AS resin, polyacetate (POM), and polycarbonate (PC). , Engineering plastics such as polyamide (PA: nylon), polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and polyphenylene sulfide (PPS), polyethersulfone (PES), polyketone (PK), polyimide (PI), poly Heat of thermoplastic resins such as cyclohexanedimethanol terephthalate (PCT), polyarylate (PAR) and various liquid crystal polymers (LCP), epoxy resin, phenol resin, novolac resin, etc. Although resistance resins, but is not limited thereto.

  The other polymer is contained in an amount of, for example, 0 parts by mass or more and less than 50 parts by mass, more preferably 1 part by mass or more and less than 70 parts by mass, when the mass of the entire polymer electrolyte membrane of the present invention is 100 parts by mass. It is appropriate. If the other polymer is less than 50 parts by mass of the entire polymer electrolyte membrane, the acid-forming group concentration in the polymer electrolyte membrane of the present invention is kept sufficiently high, and good proton conductivity is obtained. Since the polymer having a generating group can maintain the state of a continuous phase, good proton conductivity can be obtained.

(1-4) (D) Other additives For the polymer electrolyte membrane of the present invention, for example, a compatibilizer, an antioxidant, a heat stabilizer, a lubricant, a tackifier, a plasticizer, Various additives such as a cross-linking agent, a viscosity modifier, an antistatic agent, an antibacterial agent, an antifoaming agent, a dispersant, and a polymerization inhibitor can be added.
Examples of the compatibilizer include aliphatic amine compounds and polyoxazolines.

(1-5) Preparation of polymer electrolyte membrane (A) Preparation of a polymer having an acid-generating group, (B) a compound having a hydroxyl group, optional (C) other polymer, and (D) other additive, Known methods can be taken. For example, each component can be dissolved or dispersed in a solvent, and the resulting solution can be extruded and formed into a film or the like by any method such as spinning, rolling or casting to form a polymer electrolyte membrane.
(1-5-1) (A) Mixing of a polymer having an acid-generating group and (B) a compound having a hydroxyl group (B) When the polymer having a hydroxyl group is an organic polymer, together with (A) a polymer having an acid-generating group You may melt | dissolve in a solvent and you may mix further the solutions which melt | dissolved each component in the solvent. When there is no solvent that dissolves both, separate solvents that dissolve the respective components may be used in combination.
(B) When the compound having a hydroxyl group is a fine particle of an inorganic compound or an organic polymer, it may be mixed as a dispersion of the compound (B) having a hydroxyl group. For example, (A) a simple substance of a compound having a hydroxyl group (B) is mixed as it is in a solution obtained by dissolving a polymer having an acid-generating group in a solvent, or (B) a dispersion in which a compound having a hydroxyl group is dispersed in a solvent. Thus, it is possible to obtain a dispersion in which (A) a polymer having an acid-generating group is dissolved in a solvent and (B) a compound having a hydroxyl group is dispersed. Similarly, other optional components (C) and (D) can be dissolved or dispersed in the solution.

Here, examples of the solvent used for preparing the polymer electrolyte membrane of the present invention include N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and hexamethylphosphonamide. A proper one can be selected from aprotic polar solvents such as methanol and alcohols such as methanol and ethanol, but is not limited thereto. A plurality of these solvents may be used as a mixture within a possible range.
The content of the solvent is 50 to 99.9% by mass, preferably 60 to 99% by mass with respect to the solution in which each component is dissolved. If the amount of solvent is 99.9% by mass or less, good moldability can be maintained, and if it is 50% by mass or more, good workability can be maintained.

(1-5-2) Molding of polymer electrolyte membrane Before forming the electrolyte layer, the solution in which each of the components (A) to (D) is dissolved or dispersed is extruded, spun, rolled or cast It can shape | mold by the method and can be set as molded objects, such as a fiber and a film. As a method for obtaining a molded body from a solution in which the components (A) to (D) are dissolved or dispersed, a known method can be used. For example, the molded article can be obtained by removing the solvent by a method of heating or drying under reduced pressure, a method of immersing in a solvent that can be mixed with the solvent contained in the solution but not dissolving the components, and the like. it can. When the solvent is an organic solvent, the solvent is preferably distilled off by heating or drying under reduced pressure.
The shape of the molded body may be, for example, a fiber shape, a film shape, a pellet shape, a plate shape, a rod shape, a pipe shape, a ball shape, or a block shape. At this time, if necessary, the molded body may be formed in a composite form with other compounds. Preferably, in order to obtain good moldability, it is preferable to combine with a compound having a similar solubility behavior.

A preferred method for producing the polymer electrolyte membrane of the present invention is a casting method. Hereinafter, the casting method will be described as an example.
First, a solution in which the components (A) to (D) of the present invention are dissolved or dispersed is obtained, and this solution is applied to a substrate using an applicator, a doctor blade, or the like, and cast. At this time, as a method for making the thickness of the cast solution constant, in addition to the method using the applicator, the doctor blade, etc., the amount of the solution with a constant cast area using a glass petri dish or the like A conventionally known method may be used as a method for controlling the cast thickness of the solution, such as a method for controlling the thickness by concentration. Moreover, when the viscosity of a solution is high, the viscosity of a solution falls and it can cast easily by heating the base material and the solution itself which apply | coated the solution, and casting at high temperature.
The thickness of the solution at the time of casting is not particularly limited, but is, for example, 10 to 1,000 μm, preferably 50 to 750 μm. If the thickness of the solution is 10 μm or more, the form as a polymer electrolyte membrane can be sufficiently maintained, and if it is 1,000 μm or less, a uniform polymer electrolyte membrane can be obtained, which is preferable.

  Further, the solvent is removed from the cast solution by a method such as heat drying to obtain a target polymer electrolyte membrane. The removal of the solvent is preferably performed by drying from the viewpoint of the uniformity of the electrolyte layer. In order to obtain a more uniform polymer electrolyte membrane, it is preferable to adjust the removal rate of the solvent from the cast solution. In particular, in order to avoid decomposition and alteration of the components (A) to (D) and the solvent, it is desirable to dry at a temperature as low as possible under reduced pressure. For example, it is desirable that the drying temperature be as low as possible (about 40 to 100 ° C.) to slow the evaporation rate of the solvent.

(1-5-3) Configuration of Polymer Electrolyte Membrane The formed polymer electrolyte membrane may be a single layer, or may have a multilayer structure combined with other electrolyte membranes. As the other polymer electrolyte membrane, in addition to the polymer electrolyte membrane of the present invention, a polymer electrolyte membrane made of a hydrocarbon-based polymer such as polyether ketone, polysulfide, polyphosphazene, polyphenylene, etc. can be used. .
Examples of a method for obtaining a multilayer electrolyte membrane by laminating a polymer electrolyte membrane include, for example, a method of previously molding and laminating a plurality of electrolyte membranes, and a solution containing a component of the electrolyte membrane on the molded polymer electrolyte membrane The method of apply | coating and drying is mentioned. Furthermore, by repeating these combinations in combination, a multilayer electrolyte membrane having a desired layer structure can be formed.

(1-6) Properties of Polymer Electrolyte Membrane The polymer electrolyte membrane of the present invention can have any film thickness depending on the purpose, but is preferably as thin as possible from the viewpoint of proton conductivity. Specifically, the thickness is preferably 5 to 200 μm, more preferably 5 to 75 μm, and still more preferably 5 to 50 μm. When the thickness of the polymer electrolyte membrane is 5 μm or more, the handling of the polymer electrolyte membrane is improved, and when a fuel cell is produced using the polymer electrolyte membrane of the present invention, occurrence of a short circuit can be prevented appropriately. it can. Moreover, if it is 200 micrometers or less, since the electrical resistance value of a polymer electrolyte membrane becomes high and the power generation performance of a fuel cell does not fall, it is preferable.
The proton conductivity of the polymer electrolyte membrane is 0.01 S / cm or more, preferably 0.05 S / cm or more. If the proton conductivity is 0.01 S / cm or more, a good output tends to be obtained in a fuel cell using the polymer electrolyte membrane.

(2) Polymer Electrolyte Membrane-Electrode Assembly The polymer electrolyte membrane-electrode assembly of the present invention is provided on the polymer electrolyte membrane and at least one surface of the polymer electrolyte membrane, usually both surfaces of the polymer electrolyte membrane. Electrodes.
(2-1) Electrode The electrode of the present invention has a gas diffusion layer and a catalyst layer provided on and / or in the gas diffusion layer.
(2-1-1) Gas Diffusion Layer As the gas diffusion layer, for example, a known substrate having air permeability such as 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 agent made of a fluororesin such as polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, drying, and firing. Done.

(2-1-2) 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 catalytic materials and salts of the catalytic 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. In addition, in a study by K. Kinoshita et al. (J. Electrochem. Soc., 137, 845 (1990)), it is reported that the particle size of platinum having a high activity with respect to 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, and Black Pearl 2000 is used. Is appropriate.
The amount of the catalyst varies depending on the deposition method and the like, but is deposited on the surface of the gas diffusion layer in the range of, for example, about 0.02 to about 20 mg / cm ² , preferably about 0.02 to about 20 mg / cm ^2. It is appropriate. 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%.

(2-1-3) Binder The electrode of the present invention preferably has a binder in and / or on the surface of the electrode. Such a binder promotes the bond between the gas diffusion layer and the catalyst layer and the bond between the electrode and the polymer electrolyte membrane. As the binder, for example, all polymers that can be used in the present invention, and fluorine-based solid polymer electrolytes such as Nafion (R) and Flemion (R) can be used.
(2-1-4) Properties of electrode The obtained 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%.

(2-2) Production of Polymer Electrolyte Membrane-Electrode Assembly The polymer electrolyte membrane-electrode assembly of the present invention is produced by providing the electrode on the polymer electrolyte membrane. Preferably, the catalyst layer side of the electrode is joined to the polymer electrolyte membrane side. Examples of the method for producing the polymer electrolyte membrane-electrode assembly include the following three methods.
(1) A method of directly forming a catalyst layer on a polymer electrolyte membrane to form a catalyst layer and further forming a gas diffusion layer on the formed catalyst layer. For example, a perfluorocarbon polymer having an ion exchange group, a platinum group catalyst, a finely powdered carbon (carbon black) or other catalytic material containing an additive on the polymer electrolyte membrane by a method described in JP-T-2000-516014, There is a method in which a catalyst layer is formed by spraying, printing or the like, and a gas diffusion layer is heat-pressed on the catalyst layer by hot pressing or the like.
(2) A method of forming a catalyst layer by previously applying a catalyst material on a substrate, transferring the obtained catalyst layer onto a polymer electrolyte membrane, and forming a gas diffusion layer 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 Teflon (registered trademark) sheet substrate, press-molded, and then transferred onto a polymer electrolyte membrane. Further, there is a method in which a gas diffusion layer is further disposed and the obtained laminate is pressure-bonded.
(3) A method in which an electrode is prepared in advance by immersing the gas diffusion layer in a solution of a catalyst substance and the obtained electrode is provided on the polymer 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 a gas diffusion layer by dipping in a reducing agent solution such as hydrazine or Na ₂ BO ₄ .

A more preferable method for producing the polymer electrolyte 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 the polymer electrolyte membrane. Specifically, catalyst-supporting carbon particles supporting a catalyst material such as platinum-ruthenium (Pt-Ru) platinum (Pt) are used as the catalyst material, and the catalyst material is used as a solvent such as water, a solid polymer electrolyte. And a water repellent such as polytetrafluoroethylene (PTFE) particles optionally used in the manufacture of the gas diffusion layer to make a paste. This paste is directly applied or sprayed onto the polymer electrolyte membrane of the present invention to form a film, and then heated and dried to form a catalyst layer (one of the gas diffusion layer when a water repellent is included) on the polymer electrolyte. Part of the water-repellent layer). On this catalyst layer, a gas diffusion layer such as carbon paper optionally treated with water repellency is hot-pressed to produce an electrode.
The thickness of the catalyst layer at this time is, for example, 0.1 to 1000 μm, preferably 1 to 500 μm.

  As for the said paste, it is desirable to adjust the viscosity to the range of 0.1-1000 Pa * S. This viscosity can either (i) select each particle size, (ii) adjust the composition of the catalyst particles and binder, (iii) adjust the water content, or (iv) The viscosity can be adjusted preferably by adding viscosity modifiers such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose and cellulose, and polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone, sodium polyacrylate and polymethyl vinyl ether.

(3) Fuel Cell The fuel cell of the present invention uses the above polymer electrolyte membrane-electrode assembly. Examples of the fuel cell of the present invention include a solid polymer type (PEFC) and a direct methanol supply type fuel cell (DMFC).
The method for producing a fuel cell according to the present invention includes a step of arranging the polymer electrolyte membrane between two electrodes to obtain a polymer electrolyte membrane-electrode assembly.
Specifically, for example, a catalyst layer is attached on each surface of the polymer electrolyte membrane of the present invention, and further, an anode electrode and a cathode are provided on each surface of the polymer electrolyte membrane-electrode assembly provided with a gas diffusion layer. Two electrode plates of electrodes are arranged or sandwiched, and a fuel chamber capable of holding normal pressure or pressurized hydrogen gas, pressurized methanol gas or aqueous methanol solution is arranged on one surface of the obtained laminate, A fuel cell is fabricated by disposing a gas chamber capable of holding atmospheric or pressurized oxygen or air on the other surface of the laminate. The fuel cell produced in this way takes out electrical energy generated by the reaction of hydrogen or methanol and oxygen.
Further, in order to take out necessary electric power, a large number of units may be arranged in series or in parallel with this polymer electrolyte membrane-electrode assembly or laminate as one unit.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.
[Example 1]
(A) 1.2133 g of 4 ′, 4-dihydroxydiphenyl ether as a monomer for polymerizing a polymer having an acid-generating group, 1.2060 g of bis (4-chlorophenyl) sulfone as a sulfonating agent, and 4 ′, 4-dihydroxy -3,3'-disulfonic acid diphenylsulfone sodium salt 0.8817g, potassium carbonate 1.00g as catalyst, N-methylpyrrolidone 20ml as solvent, equipped with Dean-Stark trap, condenser, stirrer and nitrogen supply pipe A 50 ml 4-neck round bottom flask was charged. The mixture was heated to 100 ° C. in an oil bath, 20 ml of toluene was added, heated to 160 ° C. and refluxed for 4 hours to distill off the toluene. The temperature of the oil bath was raised to 180 ° C. to distill off toluene, and polymerization was continued at 180 ° C. for 24 hours. After cooling, the obtained polymer solution was poured into 250 ml of water to precipitate a polymer, and then the polymer was washed with water and dried to obtain a polymer having an acid-generating group (sulfonic acid group) (yield 90%). .
1.0 g of the polymer having acid-generating groups synthesized as described above and (B) 0.3 g of polyvinyl alcohol (Munit = 200,000) as a compound having a hydroxyl group were dissolved in 4 g of N-methylpyrrolidone. After casting on a glass plate, it was pre-dried at 80 ° C., followed by drying at 100 ° C. under vacuum (1 kPa), and the solvent was completely distilled off to obtain the polymer electrolyte membrane of the present invention. This polymer electrolyte membrane had a thickness of about 40 μm.

[Example 2]
(A) 0.9610 g of 2,7-dihydroxynaphthalene as a monomer for polymerizing a polymer having an acid-generating group, 1.2060 g of bis (4-chlorophenyl) sulfone as a sulfonating agent and 4,4′-dihydroxy- 0.8817 g of 3,3′-disulfonic acid diphenylsulfone sodium salt, 1.00 g of potassium carbonate as catalyst, 20 ml of N-methylpyrrolidone as solvent, 50 ml equipped with Dean-Stark trap, condenser, stirrer and nitrogen supply pipe In a four-necked round bottom flask. The mixture was heated to 100 ° C. in an oil bath, 20 ml of toluene was added, heated to 160 ° C. and refluxed for 4 hours to distill off the toluene. The temperature of the oil bath was raised to 180 ° C. to distill off toluene, and polymerization was continued at 180 ° C. for 24 hours. After cooling, the obtained polymer solution was poured into 250 ml of water to precipitate a polymer, and then the polymer was washed with water and dried to obtain a polymer having an acid-generating group (sulfonic acid group) (yield 92%). .
1.0 g of the polymer having an acid-generating group synthesized as described above and (B) 0.3 g of a phenol novolac resin (manufactured by Hitachi Chemical Co., Ltd .: Mw = 800) as a compound having a hydroxyl group are dissolved in 4 g of N-methylpyrrolidone. After casting on a glass plate, preliminary drying was performed at 80 ° C., followed by drying at 100 ° C. under vacuum (1 kPa), and the solvent was completely distilled off to obtain the polymer electrolyte membrane of the present invention. This polymer electrolyte membrane had a thickness of about 50 μm.

[Example 3]
(A) 1.2133 g of 4 ′, 4-dihydroxydiphenyl ether and 2.2056 g of bis (2- (4-fluorophenyl) -4-phenylquinolyl) ether as monomers for polymerizing the polymer having an acid-generating group, Dean Stark trap, 0.8817 g of 4,4′-dihydroxy-3,3′-disulfonic acid diphenylsulfone sodium salt as a sulfonating agent, 1.00 g of potassium carbonate as a catalyst, and 20 ml of N-methylpyrrolidone as a solvent, A 50 ml 4-neck round bottom flask equipped with a condenser, stirrer and nitrogen supply tube was charged.
The mixture was heated to 100 ° C. in an oil bath, 20 ml of toluene was added, heated to 160 ° C. and refluxed for 4 hours to distill off the toluene. The temperature of the oil bath was raised to 180 ° C. to distill off toluene, and polymerization was continued at 180 ° C. for 24 hours. After cooling, the obtained polymer solution was poured into 250 ml of water to precipitate a polymer, and then the polymer was washed with water and dried to obtain a polymer having an acid-generating group (sulfonic acid group) (yield 93%). ).
On the glass plate, 1.0 g of the polymer having an acid-generating group synthesized as described above and 0.3 g of methyl cellulose (manufactured by Wako Pure Chemical Industries, Ltd.) as a compound having a hydroxyl group (B) were dissolved in 4 g of N-methylpyrrolidone. And then dried at 100 ° C. under vacuum (1 kPa), and the solvent was completely distilled off to obtain the polymer electrolyte membrane of the present invention. This polymer electrolyte membrane had a thickness of about 50 μm.

[Example 4]
(A) 0.910Og of 2,7-dihydroxynaphthalene and 2.2056g of bis (2- (4-fluorophenyl) -4-phenylquinolyl) ether as a monomer for polymerizing a polymer having an acid-generating group, sulfone 4,817 'diphenylsulfone sodium salt 4,4'-dihydroxy-3,3'-disulfonic acid as the agent, 1.00 g potassium carbonate as the catalyst, 20 ml N-methylpyrrolidone as the solvent, Dean Stark trap, condenser In a 50 ml four-necked round bottom flask equipped with a stirrer and a nitrogen supply tube.
The mixture was heated to 100 ° C. in an oil bath, 20 ml of toluene was added, heated to 160 ° C. and refluxed for 4 hours to distill off the toluene. The temperature of the oil bath was raised to 180 ° C. to distill off toluene, and polymerization was continued at 180 ° C. for 24 hours. After cooling, the obtained polymer solution was poured into 250 ml of water to precipitate a polymer, and then the polymer was washed with water and dried to obtain a polymer having an acid-generating group (sulfonic acid group) (yield 89%). .
To a dispersion obtained by dispersing 0.3 g of lipophilic smectite (manufactured by Co-op Chemical) in 4 g of N-methylpyrrolidone, 1.0 g of the polymer having an acid-generating group synthesized above is added and dissolved in N-methylpyrrolidone. After casting on a glass plate, it was pre-dried at 80 ° C., and then dried at 100 ° C. under vacuum (1 kPa) to completely distill off the solvent, thereby obtaining the polymer electrolyte membrane of the present invention. This polymer electrolyte membrane had a thickness of about 50 μm.

[Comparative Example 1]
A polymer electrolyte membrane was obtained in the same manner as in Example 1 except that polyvinyl alcohol as a compound having a hydroxyl group (B) was not added.
Comparative Example 2 Nafion 112 (manufactured by DuPont) was used as the polymer electrolyte membrane. The film thickness was 50 μm.

<Measurement method and evaluation method>
(1) Measurement of proton conductivity The polymer electrolyte membranes obtained in the above examples and comparative examples were cut into 10 mm × 30 mm strips, and sandwiched between platinum plates (5 mm × 50 mm), and Teflon (registered trademark) The sample was sandwiched between measurement probes. The sandwiched laminate was immersed in a thermostatic bath containing warm water at 60 ° C., and the resistance between the platinum plates was measured by 1260 FREQUENCY RESPONSE ANALYSER manufactured by SOLARTRON, and the proton conductivity was obtained from the following equation.
Proton conductivity [S / cm] = Platinum plate interval [cm] / (membrane width [cm] × film thickness [cm] × resistance [Ω])
If the proton conductivity is 0.001 S / cm or less, preferably 0.01 S / cm or less, it can be said that the proton conductivity is good.

(2) Evaluation of methanol permeability After the polymer electrolyte membranes obtained in the above examples and comparative examples were immersed in purified water for 2 hours, the polymer electrolyte membrane was sandwiched between two glass cylindrical containers. The polymer electrolyte membrane is in contact with the bottom of the cylindrical container, and the bottom has an opening having an area of 8 cm ² . Two glass cylindrical containers were filled with a 20% aqueous methanol solution and purified water, respectively, so that the polymer electrolyte membrane and each liquid were in contact with each other over the entire surface of the opening. afterwards. The mixture was allowed to stand at 25 ° C. for 3 hours, and the methanol concentration of the liquid on the container side containing purified water was measured by gas chromatography. Here, the methanol concentration obtained in the case of the polymer electrolyte membrane of Comparative Example 2 was set to 100, and a relative comparison was made with the polymer electrolyte membranes of other Examples and Comparative Examples. When the relative value of the methanol concentration was 100 or less, preferably 70 or less, it was judged that the methanol permeability could be significantly suppressed.
The results of the measurement and evaluation are shown in Table 1 below.




Table 1 shows the evaluation results of the polymer electrolyte membrane.

As shown in Table 1, it can be seen that the polymer electrolyte membranes of Examples 1 to 4 can suppress the permeation of methanol while maintaining high proton conductivity.
On the other hand, it can be seen that the polymer electrolytes of Comparative Examples 1 and 2 have a larger methanol permeation amount than the polymer electrolytes of Examples 1 to 4.

<Fabrication of fuel cell>
[Preparation of polymer electrolyte membrane-electrode assembly 1]
Prepare catalyst paste C consisting of 1 g of catalyst-supported carbon particles (Tanaka Kikinzoku Co., Ltd., TEC10V30E: Valcan XC-72 with 30 wt% platinum supported), 10 g of polymer electrolyte (Aldrich, 5 wt% Nafion solution), and 2 g of water. did. The catalyst paste C was applied directly on the polymer electrolyte membrane of Example 1 placed on a hot plate using an applicator, and the electrode C was laminated. The film thickness of the obtained electrode C was 25 μm, and the amount of platinum supported in the electrode C was 1.1 mg / cm ² .
Further, on the surface opposite to the polymer electrolyte membrane surface of Example 1 on which the electrode C was formed, catalyst-supported carbon particles (manufactured by Tanaka Kikinzoku Co., Ltd., TEC61V33: Valcan XC-72 with a platinum / ruthenium alloy of 30 wt. The catalyst paste A consisting of 1 g of 1%, polymer electrolyte (manufactured by Aldrich, Nafion 5 wt% solution) 10 g, and 2 g of water was applied in the same manner as the catalyst paste C, and the electrode A was laminated. The film thickness of the obtained electrode A was 30 μm, and the amount of platinum supported in the electrode A was 1.3 mg / cm ² .
The polymer electrolyte membrane of Example 1 in which the produced electrode C and electrode A are laminated is heat-pressed by hot pressing, and carbon paper that has been subjected to water repellent treatment with PTFE is sandwiched from both sides, and then hot-pressed again. Thus, a polymer electrolyte membrane-electrode assembly 1 was obtained.

[Fuel cell 1]
A stainless steel electrode plate is provided on both sides of the polymer electrolyte membrane-electrode assembly 1, and a fuel cell constituting a fuel chamber for methanol and a gas chamber for air is arranged on the back of each electrode plate, The fuel cell 1 of the invention was produced.

[Fuel cell 2]
The polymer electrolyte membrane-electrode assembly 1 was the same as the polymer electrolyte membrane-electrode assembly 1 except that the polymer electrolyte membrane obtained in Example 3 was used as the polymer electrolyte membrane. An electrode assembly 2 was obtained. Further, the fuel cell 1 of the present invention was manufactured in the same manner as the fuel cell 1 except that hydrogen was used as the fuel added to the fuel chamber.

[Reference fuel cell 1]
In the polymer electrolyte membrane-electrode assembly 1, the reference polymer electrolyte membrane was the same as the polymer electrolyte membrane-electrode assembly 1 except that the polymer electrolyte membrane obtained in Comparative Example 1 was used as the polymer electrolyte membrane. -The electrode assembly 1 was obtained. Further, a reference fuel cell 1 was produced in the same manner as the fuel cell 1 using the reference polymer electrolyte membrane-electrode assembly 1.
[Reference fuel cell 2]
In the polymer electrolyte membrane-electrode assembly 1, the reference polymer electrolyte membrane was the same as the polymer electrolyte membrane-electrode assembly 1 except that the polymer electrolyte membrane obtained in Comparative Example 2 was used as the polymer electrolyte membrane. -The electrode assembly 2 was obtained. Further, a reference fuel cell 2 was produced in the same manner as the fuel cell 2 using the reference polymer electrolyte membrane-electrode assembly 2.

<Evaluation of fuel cell>
The fuel cell was evaluated by an electrochemical test. Specifically, the measurement was performed using the change in the output voltage when the current density was changed. The measurement conditions were a battery temperature of 80 ° C., a methanol aqueous solution concentration of 1.5 ml / liter, a methanol aqueous solution flow rate of 5 ml / min, and an oxygen flow rate of 100 ml / min.
It can be said that the lower the output voltage with respect to the current density, the less the energy density, and the more efficient the battery. The results are shown in the following graph 1 and graph 2.

  It can be seen from graphs 1 and 2 that the fuel cell of the present invention can withstand operation at high temperatures, has no deterioration in characteristics, and has good output characteristics.

Claims (6)

  A polymer electrolyte membrane comprising: (A) a polymer having an acid-generating group; and (B) a compound having a hydroxyl group.   (B) The polymer electrolyte membrane according to claim 1, wherein the compound having a hydroxyl group is at least one compound selected from the group consisting of polyvinyl alcohol, phenol resin, celluloses and smectite.   (A) The polymer electrolyte membrane according to claim 1 or 2, wherein the polymer having an acid-generating group is sulfonated polyarylene ether sulfone and / or phosphonated polyarylene ether sulfone.   A polymer electrolyte membrane-electrode assembly comprising two electrodes and the polymer electrolyte membrane according to any one of claims 1 to 3 disposed between the two electrodes.   The manufacturing method of the polymer electrolyte membrane-electrode assembly of Claim 4 including arrange | positioning the polymer electrolyte membrane of any one of Claims 1-3 between two electrodes.   A fuel cell comprising the polymer electrolyte membrane-electrode assembly according to claim 4.