JP2006252813A - Proton conductive film for direct methanol fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proton conductive film for a direct methanol fuel cell realizing both restraint of methanol crossover and reduction of electric resistance of a film. <P>SOLUTION: The proton conductive film for a direct methanol fuel cell is of a block copolymer containing iteration units containing ion-conductive groups and iteration units not containing ion-conductive groups, the ion-conductive group containing a polyarylene block copolymer that is an alkyl sulfonic group (-Z(CR<SB>2</SB>)<SB>a</SB>SO<SB>3</SB>H: where, Z is an oxygen atom or a sulfur atom, R is at least a kind of atom or group selected from a group consisting of a hydrogen atom, fluorine atom, alkyl group, and fluorine-substituted alkyl group, and 'a' is an integer of 1 to 20). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a proton conductive membrane for a direct methanol fuel cell.

  Fuel cells have high conversion efficiency from chemical energy to electrical energy and can be a clean power source. Therefore, fuel cells can be used as mobile power sources such as automobiles, distributed power sources such as residential power sources, and portable power sources such as small portable devices. Practical application is under consideration.

  Among these applications, direct methanol fuel cells (DMFC) that generate power by supplying methanol directly to the cell without reforming it into hydrogen are easy to handle and can be used as portable power sources. Therefore, it is attracting attention as a power source for portable phones, personal computers, and other portable power sources that replace conventional lithium ion batteries.

  As proton conductive membranes for DMFC (sometimes referred to as electrolyte membranes, ionic conductive membranes, etc.), perfluoroalkylsulfonic acid-based proton conductivity represented by Nafion (trademark) of DuPont, USA Membranes have been investigated. However, perfluoroalkyl sulfonic acid-based proton conducting membranes such as Nafion have high methanol permeability, so that methanol leaks from the anode side to the cathode side during use, so-called methanol crossover occurs, and battery performance is significantly reduced. There was a problem of doing.

  For this reason, a proton conducting membrane for DMFC is required to reduce the electrical resistance of the membrane while suppressing methanol crossover. However, these physical properties are generally in a trade-off relationship, and it has been extremely difficult to achieve both.

  An object of the present invention is to provide a proton conducting membrane for DMFC that solves the above-described problems in the prior art and achieves both suppression of methanol crossover and reduction of electrical resistance of the membrane.

According to the present invention, the following proton conductive membrane for DMFC is provided to solve the above-mentioned problems of the present invention.
[1] A block copolymer comprising a repeating unit containing an ion conductive group and a repeating unit not containing an ion conductive group, wherein the polyarylene block copolymer wherein the ion conductive group is an alkylsulfonic acid group. A proton conductive membrane for a direct methanol fuel cell, comprising a polymer.
[2]
In the polyarylene block copolymer, the repeating unit containing an ion conductive group is a repeating unit represented by the following general formula (1), and the repeating unit not containing an ion conductive group is represented by the following general formula (2). The proton conducting membrane for a direct methanol fuel cell according to claim 1, wherein the proton conducting membrane is a repeating unit represented by:

[In the formula (1), X and Y represent a divalent organic group or a single bond, Z represents an oxygen atom or a sulfur atom, R represents a group consisting of a hydrogen atom, a fluorine atom, an alkyl group and a fluorine-substituted alkyl group. At least one atom or group selected from the above, a is an integer of 1 to 20, n is an integer of 1 to 5, and m is an integer of 0 to 10; ]

[In formula (2), R ^{1 to} R ⁸ may be the same or different from each other, and are selected from the group consisting of a hydrogen atom, a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, an allyl group, an aryl group, and a cyano group. And at least one atom or group, W represents a divalent electron-withdrawing group or single bond, T represents a single bond, a divalent electron-withdrawing group, a divalent electron-donating group, or the following general formula: (3) represents a divalent group represented by (4), p represents a positive integer, and R ^{1 to} R ⁸ , W and T are independent of each other for each of p repeating units constituting the block. It is. ]

[In the formulas (3) and (4), R ^{9 to} R ²⁰ may be the same or different from each other, and are a hydrogen atom, a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, an allyl group, an aryl group, a cyano group, or 2 Represents at least one atom or group selected from the group consisting of valent electron-withdrawing groups, K represents a single bond or a divalent electron-donating group, J represents a single bond, an alkylene group, or a fluorine-substituted alkylene group. , aryl substituted alkylene group, alkenylene group, alkynylene group, an arylene group, a fluorenylidene group, -O -, - S -, - CO -, - CONH -, - COO -, - SO- or -SO ₂ - shows a block K, l, m, i, X, and T are independent of each other for each of the p repeating units that constitute. ].
[3] The polyarylene block copolymer comprises 0.1 to 99.9 mol% of the repeating unit represented by the general formula (1) and 0.1 to the repeating unit represented by the general formula (2). The proton conductive membrane for a direct methanol fuel cell as described in [2], which comprises ˜99.9 mol%.
[4]
The proton conductive membrane for direct methanol fuel cells according to [1] to [3], wherein the polyarylene block copolymer has an ion exchange capacity of 0.3 to 5.0 meq / g.

  According to the present invention, by using a polyarylene block copolymer having an alkylsulfonic acid group as an ion conductive group, methanol crossover is suppressed, and the electric resistance of the membrane is reduced. It is possible to provide a proton conductive membrane for DMFC that has a small area change with respect to an aqueous solution and can be used at a high concentration.

[Detailed Description of the Invention]
Hereinafter, the proton conductive membrane for DMFC of the present invention will be specifically described.
The proton conductive membrane for DMFC according to the present invention is a block copolymer comprising a repeating unit containing an ion conductive group and a repeating unit not containing an ion conductive group, wherein the ion conductive group is an alkylsulfone. The polyarylene block copolymer which is an acid group is included.

  In the present invention, the repeating unit containing an ion conductive group is a repeating unit represented by the following general formula (1), and the repeating unit not containing an ion conductive group is represented by the following general formula (2). Preferably it is a unit. Hereinafter, such a preferable polyarylene block copolymer will be described.

(Polyarylene block copolymer)
The polyarylene block copolymer preferably used in the present invention includes a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2).

In the formula, X and Y represent a divalent organic group or a single bond (-). Examples of the divalent organic group include —CO—, —CONH—, — (CF ₂ ) _q — (where q is an integer of 1 to 10), —C (CF ₃ ) ₂ —, —COO. -, - SO -, - SO 2 - electron-withdrawing groups such as,
-O-, -S-, -CH = CH-, -C≡C- and the following formula

And an electron donating group such as a group represented by
X is preferably an electron-withdrawing group, particularly preferably —CO— or —SO ₂ — from the viewpoint of high polymerization activity during production of the polyarylene block copolymer. On the other hand, Y may or may not be electron withdrawing.

The electron-withdrawing group refers to a group having a Hammett substituent constant of 0.06 or more when the phenyl group is in the m-position and 0.01 or more when it is in the p-position.
Z represents an oxygen atom or a sulfur atom.

  R represents at least one atom or group selected from the group consisting of a hydrogen atom, a fluorine atom, an alkyl group, and a fluorine-substituted alkyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, and a hexyl group, and a methyl group and an ethyl group are preferable. Examples of the fluorine-substituted alkyl group include trifluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group, perfluorohexyl group, trifluoromethyl group, pentafluoroethyl group, and the like. Etc. are preferable.

  a represents an integer of 1 to 20, n represents an integer of 1 to 5, and m represents an integer of 0 to 10.

In the general formula (2), R ^{1 to} R ⁸ may be the same as or different from each other, and at least 1 selected from the group consisting of a hydrogen atom, a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, an allyl group, and an aryl group. Indicates an atom or group of species. Here, examples of the alkyl group and the fluorine-substituted alkyl group include those exemplified as the alkyl group and fluorine-substituted alkyl group represented by R in the general formula (1). Examples of the allyl group include a propenyl group, and examples of the aryl group include a phenyl group and a pentafluorophenyl group.

W is a divalent electron-withdrawing group, the electron withdrawing group, e.g. -CO -, - CONH -, - (CF 2) q - ( wherein, q is an integer of 1 to 10), —C (CF ₃ ) ₂ —, —COO—, —SO—, —SO ₂ — and the like can be mentioned.

  T represents a single bond, a divalent electron-withdrawing group, a divalent electron-donating group, or a divalent group represented by the following general formula (3) or (4). As the electron-withdrawing group, the groups exemplified as the aforementioned W can be used. Examples of the electron donating group include —O—, —S—, —CH═CH—, —C≡C—, and

Group represented by these.

In formulas (3) and (4), R ^{9 to} R ²⁰ may be the same or different from each other, and are a hydrogen atom, a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, an allyl group, an aryl group, and a cyano group or a divalent group. And at least one atom or group selected from the group consisting of the above electron-withdrawing groups, specifically, the same atoms or groups as R ^{1 to} R ^{8 in} the general formula (2).

K represents a single bond or a divalent electron donating group. Examples of the divalent electron donating group include —O—, —S—, —CH═CH—, —C≡C— and the like.
J represents a single bond, an alkylene group, a fluorine-substituted alkylene group, an aryl-substituted alkylene group, an alkenylene group, an alkynylene group, an arylene group, a fluorenylidene group, -O-, -S-, -CO-, -CONH-, -COO-, -SO- or -SO ₂ - shows the.

Specific examples of the alkylene group, fluorine-substituted alkylene group, aryl-substituted alkylene group, alkenylene group, alkynylene group, arylene group, and fluorenylidene group include, for example, —C (CH ₃ ) ₂ —, —CH═CH—, —CH═. CH—CH ₂ —, —C≡C—, — (CF ₂ ) _p —
(Here, p is an integer of 1 to _{10), - C (CF 3)} 2 -, the following formula

Group represented by these.
p is 0 or a positive integer, and the upper limit is usually 100, preferably 80.
Note that R ^{1 to} R ⁸ , W and T are independent of each other for the p repeating units constituting the block, and k, l, m, i, X for each of the p repeating units constituting the block. And T are independent of each other.

  The polyarylene block copolymer has a constitutional unit represented by the general formula (1) of 0.1 to 99.9 mol%, preferably 0.5 to 99.5 mol%, represented by the following general formula (2). The structural unit represented may be 0.1 to 99.9 mol%, preferably 0.5 to 99.5 mol%.

The molecular weight of the polyarylene block copolymer is 10,000 to 1,000,000, preferably 20,000 to 800,000 in terms of polystyrene by gel permeation chromatography (GPC), and in terms of polystyrene in terms of polystyrene by GPC. 0.5 to 200,000, preferably 1 to 160,000. If it is less than 10,000, the coating film properties are insufficient, such as cracking in the molded film, and the strength properties are also problematic. On the other hand, when it exceeds 1,000,000, there are problems such as insufficient solubility, high solution viscosity, and poor workability.

  The amount of sulfonic acid groups (ion exchange capacity) in the polyarylene block copolymer is 0.5 to 3 meq / g, preferably 0.8 to 2.8 meq / g. If it is less than 0.5 meq / g, proton conductivity may not be improved. On the other hand, if it exceeds 3 meq / g, the hydrophilicity is improved and it becomes soluble in hot water even if it is not water-soluble polymer or water-soluble. In addition, durability may be reduced even if water solubility is not reached.

Structure of polyarylene block copolymer, for example, by an infrared absorption spectrum, 1,030~1,045cm ^-1, S = O absorption at 1,160~1,190cm ^-1, 1,130~1,250cm ^{- It} can be confirmed by C—O—C absorption of ¹ and C═O absorption of 1,640 to 1,660 cm ⁻¹ , and the composition ratio can be known by neutralization titration of sulfonic acid or elemental analysis. Moreover, the structure can be confirmed from the peak of the aromatic proton at 6.8 to 8.0 ppm by nuclear magnetic resonance spectrum ( ¹ H-NMR).

(Method for producing polyarylene block copolymer)
The polyarylene block copolymer is produced by reacting the compound (A) with the compound (B) or the compound (C). Hereinafter, the compound (A), the compound (B) and the compound (C) used for producing the polyarylene block copolymer will be described in order.

{Compound (A)}
The compound (A) has a repeating unit represented by the following general formula (5) and a repeating unit represented by the above general formula (2).

In the general formula (5), X, Y, Z, n, and m are as defined in the general formula (1), and M represents a hydrogen atom or an alkali metal atom.
Examples of the alkali metal atom represented by M include sodium, potassium, lithium and the like.

Compound (A) includes at least one compound (A ₁ ) represented by the following general formula (6) and another aromatic compound (preferably at least one compound represented by the following general formula (7). (A ₂
And)) as monomers, respectively. Specifically, as shown in Equation (9) described later, compounds when (A ₁₎ R ⁹ (the following general formula (6) refer) in is a hydrocarbon group, the compound (A ₁₎ and Compound ( A ₂ ) Other aromatic compounds are polymerized to obtain a compound (A ′), and then the hydrocarbon group represented by R ⁹ is removed to obtain the compound (
A) can be obtained.

In the general formula (6), X, Y, Z, n, and m are as defined in the general formula (1), and R ′ and R ″ may be the same or different from each other, and each represents a fluorine atom. A group represented by an excluded halogen atom (chlorine, bromine, iodine) or —OSO ₂ Q (where Q represents an alkyl group, a fluorine-substituted alkyl group, or an aryl group).

  Examples of the alkyl group represented by Q include a methyl group and an ethyl group, examples of the fluorine-substituted alkyl group include a trifluoromethyl group, and examples of the aryl group include a phenyl group and a p-tolyl group.

R ⁹ represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a hydrocarbon group having 1 to 20 carbon atoms having a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom. Specific examples of the hydrocarbon group include methyl, ethyl, n-propyl, iso-propyl, tert-butyl, iso-butyl, n-butyl, sec-butyl, neopentyl, Cyclopentyl group, hexyl group, cyclohexyl group, cyclopentylmethyl group, cyclohexylmethyl group, adamantyl group, adamantylmethyl group, 2-ethylhexyl group, bicyclo [2.2.1] heptyl group, bicyclo [2.2.1] heptylmethyl Group, tetrahydrofurfuryl group, 2-methylbutyl group, 3,3-dimethyl-2,4-dioxolane methyl group and other linear hydrocarbon groups, branched hydrocarbon groups, alicyclic hydrocarbon groups, 5-membered Examples thereof include a hydrocarbon group having a heterocyclic ring. Examples of the hydrocarbon group containing an oxygen atom among the hydrocarbon groups having 1 to 20 carbon atoms having a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom include a tetrahydro-2-pyranyl group, a methoxymethyl group, and an ethoxy group. Examples thereof include an ethyl group and a propoxymethyl group. Of these, a tetrahydro-2-pyranyl group and a methoxymethyl group are preferred.

In the general formula (7), R ^{1 to} R ⁸ , W, T, and p are as defined in the general formula (2), and R ′ and R ″ may be the same or different from each other. , A halogen atom excluding a fluorine atom or a group represented by —OSO ₂ Q (where Q represents an alkyl group, a fluorine-substituted alkyl group or an aryl group). Examples of Q include the groups exemplified in the general formula (6).

Next, the compound (A ₁ ) and the compound (A ₂ ) will be described respectively.
<< Compound (A ₁ ) >>
Compound (A ₁ ) can be synthesized, for example, by the following method. In this case, an aromatic acid halogen compound is used as a starting material (compound (I)), and the compound (A ₁ ′) obtained by reacting this aromatic acid halogen compound with anisole contains a hydroxyl group. Although the case where the protecting group for the hydroxyl group is a tetrahydro-2-pyranyl group has been shown, the compound (A ₁ ′), the reactant, and the protecting group are not limited thereto. For example, instead of anisole, an aromatic acid halogen compound and other reactants (eg, 1,4-dimethoxybenzene, 1,3-dimethoxybenzene, 1,2-dimethoxybenzene, 1,2,3-trimethoxybenzene) Or methylthiobenzene) can be reacted.

(I) Friedel-Crafts acylation
For example, after adding aluminum chloride to a dichloromethane solution of anisole in an ice bath (−10 ° C.), the compound (I) is dropped and stirred at room temperature for 1 to 12 hours. Next, the reaction solution is poured into ice water containing concentrated hydrochloric acid, and the separated organic layer is extracted with a 10% aqueous sodium hydroxide solution. The aqueous layer is neutralized with hydrochloric acid, and the precipitated solid is converted into an organic solvent (for example, ethyl acetate). Then, the extract is concentrated and then recrystallized as necessary to obtain a compound (A ₁ ′) containing an acyl group and a hydroxyl group. In the above step, when methylthiobenzene is used instead of anisole, the compound (A ₁ ′) has a thiol group.

In the polyarylene of the present invention finally obtained by adjusting the substitution position and the number of substitutions of the hydroxyl group (or thiol group) on the aromatic ring in the compound (A ₁ ′), the introduction position of the sulfonic acid group and The amount introduced can be controlled. That is, in this step (Friedel-Crafts acylation reaction), a predetermined position is substituted with an OR group or an SR group (for example, R = hydrogen atom, methyl group, ethyl group, t-butyl group alkyl group, etc.). By using benzene, the introduction position and introduction amount of the sulfonic acid group in the finally obtained polyarylene of the present invention can be controlled.

(Ii) Introduction of protecting group For example, the compound (A ₁ ') and 1 to 20-fold molar amount of 2H-dihydropyran are dissolved in toluene in the presence of an acid catalyst (for example, a cation exchange resin). Allow to stir at room temperature for 1-24 hours. Next, after removing the acid catalyst, the toluene solution is concentrated and then recrystallized as necessary to obtain a compound (A ₁ ) having a tetrahydro-2-pyranyl group introduced as a protecting group. In the above step, when methylthiobenzene is used instead of anisole, the tetrahydro-2-pyranyl group functions as a thiol protecting group.

The compound represented by the general formula (6) (A _1), for example, the following compounds.

Examples of the compound (A ₁ ) represented by the general formula (6) include a compound in which a chlorine atom is replaced with a bromine atom or an iodine atom in the above compound, and a compound in which —CO— is replaced with —SO ₂ — in the above compound. And compounds in which the chlorine atom is replaced by a bromine atom or an iodine atom and -CO- is replaced by -SO ₂ -in the above compound.

<< Compound (A ₂ ) >>
The compound (A ₂ ) is represented by the general formula (7). Specifically, as the compound represented by the general formula (7), when p = 0, for example, 4,4′-dichlorobenzophenone, 4,4′-dichlorobenzanilide, bis (chlorophenyl) difluoromethane, 2, 2-bis (4-
Chlorophenyl) hexafluoropropane, 4-chlorobenzoic acid-4-chlorophenyl, bis (4-chlorophenyl) sulfoxide, bis (4-chlorophenyl) sulfone, 2,6-dichlorobenzonitrile, 9,9-bis (4-hydroxyphenyl) ) Fluorene. In these compounds, compounds in which a chlorine atom is replaced with a bromine atom or an iodine atom, and compounds in which at least one of halogen atoms substituted in the 4-position in these compounds are substituted in the 3-position are exemplified.

When p = 1, the specific compound represented by the general formula (7) is, for example, 4,
4′-bis (4-chlorobenzoyl) diphenyl ether, 4,4′-bis (4-chlorobenzoylamino) diphenyl ether, 4,4′-bis (4-chlorophenylsulfonyl) diphenyl ether, 4,4′-bis (4- Chlorophenyl) diphenyl ether dicarboxylate, 4,4′-bis [(4-chlorophenyl) -1,1,1,3,3,3-hexafluoropropyl] diphenyl ether, 4,4′-bis [(4-chlorophenyl) Tetrafluoroethyl] diphenyl ether, compounds in which the chlorine atom is replaced with a bromine atom or iodine atom in these compounds, compounds in which the halogen atom substituted in the 4-position in these compounds is substituted in the 3-position, and further in these compounds, diphenyl ether At least one of the groups substituted in the 4-position is in the 3-position And the like.

Further, the compound represented by the general formula (7) is 2,2-bis [4- {4- (4-
Chlorobenzoyl) phenoxy} phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- {4- (4-chlorobenzoyl) phenoxy} phenyl] sulfone, and the following formula Compounds.

The compound represented by the general formula (7) can be synthesized, for example, by the method shown below.
First, in order to convert the bisphenol linked with an electron-withdrawing group into the corresponding alkali metal salt of bisphenol, dielectrics such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, sulfolane, diphenylsulfone, dimethylsulfoxide, etc. Add an alkali metal such as lithium, sodium or potassium, an alkali metal hydride, an alkali metal hydroxide, an alkali metal carbonate or the like in a polar solvent having a high rate.

Usually, the alkali metal is reacted in excess with respect to the hydroxyl group of phenol, and usually 1.1 to 2 times equivalent is used. Preferably, 1.2 to 1.5 times equivalent is used. In this case, fluorine, chlorine, etc. activated with an electron-withdrawing group in the presence of azeotropic solvent such as benzene, toluene, xylene, hexane, cyclohexane, octane, chlorobenzene, dioxane, tetrahydrofuran, anisole, phenetole, etc. Aromatic halogen-substituted aromatic dihalide compounds such as 4,4′-difluorobenzophenone, 4,4′-dichlorobenzophenone, 4,4′-chlorofluorobenzophenone, bis (4-chlorophenyl) sulfone, bis (4 -Fluorophenyl) sulfone, 4-fluorophenyl-4'-chlorophenylsulfone, bis (3-nitro-4-chlorophenyl) sulfone, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile, hexafluorobenzene, deca Fluorobiphenyl, , 5-difluorobenzophenone, 1,3-bis (4-chlorobenzoyl) reacting benzene. In terms of reactivity, a fluorine compound is preferable, but in consideration of the following aromatic coupling reaction, it is necessary to assemble an aromatic nucleophilic substitution reaction so that the terminal is a chlorine atom. The active aromatic dihalide is used in an amount of 2 to 4 times mol, preferably 2.2 to 2.8 times mol, of bisphenol. Prior to the aromatic nucleophilic substitution reaction, an alkali metal salt of bisphenol may be used. The reaction temperature is 60 ° C to 300 ° C, preferably 80 ° C to 250 ° C. The reaction time ranges from 15 minutes to 100 hours, preferably from 1 hour to 24 hours. The most preferable method is to use a chlorofluoro compound having one halogen atom having a different reactivity as the active aromatic dihalide represented by the following formula, and a nucleophilic substitution reaction with phenoxide occurs preferentially by the fluorine atom. It is convenient to obtain the desired activated terminal chloro form.

(Wherein, W is as defined for general formula (2).)
In addition, the compound represented by the general formula (7) is a combination of a nucleophilic substitution reaction and an electrophilic substitution reaction as described in JP-A-2-159. It can also be synthesized by synthesizing a flexible compound comprising:

Specifically, an aromatic bishalide activated with an electron-withdrawing group, for example, bis (4-chlorophenyl) sulfone is subjected to a nucleophilic substitution reaction with phenol to obtain a bisphenoxy-substituted product. Subsequently, the compound of interest can be obtained, for example, by performing a Friedel-Crafts reaction with 4-chlorobenzoic acid chloride using this substituted product. As the aromatic bishalide activated with the electron-withdrawing group used here, the compounds exemplified above can be applied. The phenol compound may be substituted, but an unsubstituted compound is preferable from the viewpoint of heat resistance and flexibility. In addition, it is preferable to use an alkali metal salt for the substitution reaction of phenol, and as the usable alkali metal compound, the compounds exemplified above can be used. The amount used is 1.2 to 2 moles per mole of phenol. In the reaction, the polar solvent described above or an azeotropic solvent with water can be used. The bisphenoxy compound is reacted with chlorobenzoic acid chloride as an acylating agent in the presence of an activator for the Friedel-Crafts reaction of Lewis acids such as aluminum chloride, boron trifluoride, and zinc chloride. Chlorobenzoic acid chloride can be used in an amount of 2 to 4 times mol, preferably 2.2 to 3 times mol, of the bisphenoxy compound. The Friedel-Craft activator is used in an amount of 1.1 to 2 times equivalent to 1 mol of an active halide compound such as chlorobenzoic acid as an acylating agent. The reaction time ranges from 15 minutes to 10 hours, and the reaction temperature ranges from -20 ° C to 80 ° C. As the solvent used, an inert solvent (for example, chlorobenzene or nitrobenzene) can be used in the Friedel-Crafts reaction.

In addition, in the general formula (7), the compound in which p is 2 or more includes, for example, at least one bisphenol serving as a source of etheric oxygen which is the electron donating group T in the general formula (7), and an electron A compound in combination with at least one group selected from> C═O, —SO ₂ — and> C (CF ₃ ) ₂ which is an attractive group W, specifically 2,2-bis (4- Alkalis of bisphenols such as hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-hydroxyphenyl) ketone, 2,2-bis (4-hydroxyphenyl) sulfone A substitution reaction of a metal salt with an excess of an active aromatic halogen compound such as 4,4-dichlorobenzophenone or bis (4-chlorophenyl) sulfone is performed with N-methyl-2.
It is obtained by sequentially polymerizing the monomer in the presence of a polar solvent such as pyrrolidone, N, N-dimethylacetamide, or sulfolane.

  Examples of such compounds include compounds represented by the following formulas.

In the above, p is 0 or a positive integer, and the upper limit is usually 100, preferably 10-80.
《Catalyst and others》
The catalyst used when the compound (A ₁ ) is polymerized as a monomer or when the compound (A ₁ ) and the compound (A ₂ ) are respectively polymerized as monomers is a catalyst system containing a transition metal compound, and this catalyst The system includes (i) a transition metal salt and a compound to be a ligand (hereinafter referred to as “ligand component”), or a transition metal complex in which a ligand is coordinated (including a copper salt), and (Ii) A reducing agent is an essential component, and a “salt” may be added to increase the polymerization rate.

  Here, as the transition metal salt, nickel compounds such as nickel chloride, nickel bromide, nickel iodide and nickel acetylacetonate; palladium compounds such as palladium chloride, palladium bromide and palladium iodide; iron chloride and iron bromide And iron compounds such as iron iodide; cobalt compounds such as cobalt chloride, cobalt bromide, and cobalt iodide. Of these, nickel chloride, nickel bromide and the like are particularly preferable.

As the ligand component, triphenylphosphine, 2,2′-bipyridine, 1,5-
Examples include cyclooctadiene and 1,3-bis (diphenylphosphino) propane. Of these, triphenylphosphine and 2,2′-bipyridine are preferred. The compound which is the said ligand component can be used individually by 1 type or in combination of 2 or more types.

Furthermore, as the transition metal complex in which the ligand is coordinated, for example, nickel chloride bis (triphenylphosphine), nickel bromide bis (triphenylphosphine), nickel iodide bis (triphenylphosphine), nickel nitrate bis (Triphenylphosphine), nickel chloride (2,2'-bipyridine), nickel bromide (2,2'-bipyridine), nickel iodide (2,2'-bipyridine), nickel nitrate (2,2'-bipyridine) ), Bis (1,5-cyclooctadiene) nickel, tetrakis (triphenylphosphine) nickel, tetrakis (triphenylphosphite) nickel, tetrakis (triphenylphosphine) palladium and the like. Of these, nickel chloride bis (triphenylphosphine) and nickel chloride (2,2′-bipyridine) are preferred.

  Examples of the reducing agent that can be used in the catalyst system include iron, zinc, manganese, aluminum, magnesium, sodium, calcium, and the like. Of these, zinc, magnesium and manganese are preferred. These reducing agents can be used after being more activated by contacting with an acid such as an organic acid.

  Examples of the “salt” that can be used in the above catalyst system include sodium compounds such as sodium fluoride, sodium chloride, sodium bromide, sodium iodide, sodium sulfate, potassium fluoride, potassium chloride, potassium bromide, Examples include potassium compounds such as potassium iodide and potassium sulfate; ammonium compounds such as tetraethylammonium fluoride, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, and tetraethylammonium sulfate. Of these, sodium bromide, sodium iodide, potassium bromide, tetraethylammonium bromide, and tetraethylammonium iodide are preferred.

  The proportion of each component used is usually 0.0001 to 10 mol, preferably 0.01 to 0.5 mol, per 1 mol of the total amount of the above monomers of the transition metal salt or transition metal complex. When the amount is less than 0.0001 mol, the polymerization reaction may not proceed sufficiently. On the other hand, when the amount exceeds 10 mol, the molecular weight may decrease.

  When a transition metal salt and a ligand component are used in the catalyst system, the ratio of the ligand component used is usually 0.1 to 100 mol, preferably 1 to 10 mol, per 1 mol of the transition metal salt. is there. When the amount is less than 0.1 mol, the catalytic activity may be insufficient. On the other hand, when the amount exceeds 100 mol, the molecular weight may decrease.

Moreover, the usage-amount of a reducing agent is 0.1-100 normally with respect to 1 mol of total of the said monomer.
Mol, preferably 1 to 10 mol. If the amount is less than 0.1 mol, polymerization may not proceed sufficiently. If the amount exceeds 100 mol, purification of the resulting polymer may be difficult.

  Furthermore, when using "salt", the usage-ratio is 0.001-100 mol normally with respect to the total of 1 mol of the said monomer, Preferably it is 0.01-1 mol. If it is less than 0.001 mol, the effect of increasing the polymerization rate may be insufficient, and if it exceeds 100 mol, purification of the resulting polymer may be difficult.

  Examples of polymerization solvents that can be used include tetrahydrofuran, cyclohexanone, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, γ-butyrolactone, sulfolane, γ-butyrolactam, Examples thereof include dimethylimidazolidinone and tetramethylurea. Of these, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, and N-methyl-2-pyrrolidone are preferable. These polymerization solvents are preferably used after sufficiently dried.

The total concentration of the monomers in the polymerization solvent is usually 1 to 90% by weight, preferably 5 to 40% by weight.
Moreover, the superposition | polymerization temperature at the time of superposing | polymerizing is 0-200 degreeC normally, Preferably it is 50-120 degreeC. The polymerization time is usually 0.5 to 100 hours, preferably 1 to 40 hours.

An example of a reaction formula for obtaining the compound (A) by reacting the compound (A ₁ ) with the compound (A ₂ ) is shown in the following formula (9). In the following formula, x and y are positive integers, and indicate molar ratios when x + y = 100 mol%. As shown in the following formula (9), the compound (A ₁ ) and the compound (A ₂ ) first react to produce the compound (A ′). Then
R ^{9 in} this compound (A ′) is removed to produce compound (A).

Specifically, at least one compound (A ₁ ) represented by the general formula (6) 0.1-9
9.9 mol% and (preferably 0.5 to 99.5 mol%), other aromatic monomers, preferably at least one compound represented by the general formula (7) (A ₂₎ 0.1 ~ 99.9 mol%
(Preferably 0.5 to 99.5 mol%) is preferably reacted in the presence of a catalyst to obtain compound (A).

{Compound (B)}
The compound (B) is represented by the following general formula (10).

In the general formula (10), R and a are as defined in the general formula (1).
Examples of the compound (B) include compounds represented by the following formula.
In producing the polyarylene of the present invention, by adjusting the number of carbon atoms of the compound (B), that is, the number of “a” in the general formula (10), in the finally obtained polyarylene block copolymer, The introduction position and introduction amount of the sulfonic acid group can be adjusted.

{Synthesis example of polyarylene block copolymer}
A polyarylene block preferably used in the present invention by reacting the compound (A) containing the structural unit represented by the general formula (5) with the compound (B) represented by the general formula (10). A copolymer is obtained.

  Next, a synthesis example of a polyarylene block copolymer using the compound (A) and the compound (B) is shown. The reaction of the compound (A) and the compound (B) can be carried out by dissolving the compound (A) and the compound (B) in a solvent under basic conditions as shown in the following formula (11), for example.

For example, when M is a hydrogen atom in the compound (A) (see general formula (5)), N-methyl-2-pyrrolidone, N, N-dimethylacetamide, sulfolane, diphenylsulfone, dimethylsulfoxide, etc. By adding an alkali metal, alkali metal hydride, alkali metal carbonate or the like as necessary in a polar solvent having a high dielectric constant, a compound (
A) can be an alkali metal salt.

  Examples of the alkali metal include lithium, sodium, and potassium, and examples of the alkali metal hydride, alkali metal hydroxide, and alkali metal carbonate include the alkali metal hydride, hydroxide, and carbonate, respectively. .

  Usually, the alkali metal is reacted in excess with respect to the sulfonic acid group in the compound (A), and usually 1.1 to 4 times the equivalent amount of the sulfonic acid group is used. Preferably, 1.2 to 3 times equivalent is used.

  In the reaction between the compound (A) and the compound (B), under basic conditions, the oxygen atom or sulfur atom represented by Z in the compound (A) is changed to a carbon atom adjacent to the oxygen atom of the compound (B). On the other hand, a nucleophilic substitution reaction occurs, and the compound (B) opens. A specific example of the above reaction is shown in the following formula (12). Here, the compound (A) and the compound (B) and the alkaline reagent used are not limited to these.

{Compound (C)}
The compound (C) is represented by the following general formula (13).

In the said General formula (13), R and a are as the definition in the said General formula (1), L shows either a chlorine atom, a bromine atom, and an iodine atom.
Examples of the compound (C) include compounds represented by the following formulas. In the following compounds, K, Li or H may be used instead of Na. Further, Br or I may be used instead of Cl.

  In producing the polyarylene of the present invention, by adjusting the number of carbon atoms of the compound (C), that is, the number of “a” in the general formula (13), The introduction position and introduction amount of the acid group can be adjusted.

{Synthesis example of polyarylene block copolymer}
A polyarylene block preferably used in the present invention by reacting the compound (A) containing the structural unit represented by the general formula (5) with the compound (C) represented by the general formula (13). A copolymer is obtained.

  Next, a synthesis example of a polyarylene block copolymer using the compound (A) and the compound (C) is shown. The reaction between the compound (A) and the compound (C) can be carried out by dissolving the compound (A) and the compound (C) in a solvent under basic conditions, for example, as shown in the following formula (14).

In the reaction between the compound (A) and the compound (C), for example, the polar solvent and the alkali reagent exemplified in the reaction between the compound (A) and the compound (B) described above can be used.
In the reaction between the compound (A) and the compound (C), under basic conditions, the oxygen atom or sulfur atom represented by Z in the compound (A) is changed to a carbon atom adjacent to the oxygen atom of the compound (B). In contrast, a nucleophilic substitution reaction occurs. A specific example of the above reaction is shown in the following formula (15). Here, the compound (A) and the compound (C) and the alkaline reagent used are not limited to these.

(Proton conducting membrane for direct methanol fuel cell)
The proton conductive membrane for direct methanol fuel cells is obtained from the polyarylene block copolymer described above. When preparing a proton conducting membrane from a polyarylene block copolymer, in addition to the polyarylene block copolymer, an inorganic acid such as sulfuric acid and phosphoric acid, an organic acid containing a carboxylic acid, an appropriate amount of water, etc. are used in combination. May be.

  In the proton conductive membrane for a direct methanol fuel cell of the present invention, the polyarylene block copolymer is dissolved in a solvent to form a solution, and then cast on a substrate by casting to form a film (casting) Method) or the like to form a film. Here, the substrate is not particularly limited as long as it is a substrate used in an ordinary solution casting method. For example, a substrate made of plastic, metal, or the like is used. Preferably, for example, a polyethylene terephthalate (PET) film or the like is used. A substrate made of a thermoplastic resin is used.

  Examples of the solvent for dissolving the polyarylene block copolymer include N-methyl-2-pyrrolidone, N, N-dimethylformamide, γ-butyrolactone, N, N-dimethylacetamide, dimethyl sulfoxide, dimethylurea, dimethylimidazolidinone. An aprotic polar solvent such as N-methyl-2-pyrrolidone (hereinafter also referred to as “NMP”) is preferable from the viewpoint of solubility and solution viscosity. The aprotic polar solvent can be used alone or in combination of two or more.

  In addition, as a solvent for dissolving the polyarylene block copolymer, a mixture of the above aprotic polar solvent and alcohol can also be used. Examples of the alcohol include methanol, ethanol, propyl alcohol, iso-propyl alcohol, sec-butyl alcohol, tert-butyl alcohol and the like, and methanol is particularly preferable because it has an effect of lowering the solution viscosity in a wide composition range. Alcohol can be used alone or in combination of two or more.

  When a mixture of an aprotic polar solvent and an alcohol is used as the solvent, the aprotic polar solvent is 95 to 25% by weight, preferably 90 to 25% by weight, and the alcohol is 5 to 75% by weight, preferably 10 to 10%. 75% by weight (however, the total is 100% by weight). When the amount of alcohol is within the above range, the effect of lowering the solution viscosity is excellent.

  The polymer concentration of the solution in which the polyarylene block copolymer is dissolved is usually 5 to 40% by weight, preferably 7 to 25% by weight, although it depends on the molecular weight of the polyarylene block copolymer. If it is less than 5% by weight, it is difficult to form a thick film, and pinholes are easily generated. On the other hand, if it exceeds 40% by weight, the solution viscosity is so high that it is difficult to form a film, and surface smoothness may be lacking.

The solution viscosity is usually 2,000 to 100,000 mPa · s, preferably 3,000 to 50,000 mPa · s, although it depends on the molecular weight of the polyarylene block copolymer and the polymer concentration. If it is less than 2,000 mPa · s, the retention of the solution during film formation is poor, and it may flow from the substrate. On the other hand, if it exceeds 100,000 mPa · s, the viscosity is too high to be extruded from the die and it may be difficult to form a film by the casting method.

  After film formation as described above, by immersing the obtained undried film in water, the organic solvent in the undried film can be replaced with water, and the residual solvent amount of the resulting proton conducting membrane can be reduced. Can be reduced.

  In addition, after film formation, before immersing an undried film in water, you may predry an undried film. The preliminary drying is performed by holding the undried film at a temperature of usually 50 to 150 ° C. for 0.1 to 10 hours.

  When immersing an undried film in water, it may be a batch system in which a single wafer is immersed in water, or a laminated film in a state of being formed on a substrate film (for example, PET) that is usually obtained, Alternatively, a continuous method in which a film separated from a substrate is dipped in water and wound is also applicable.

In the case of the batch method, a method of placing the treated film in a frame is advantageous in that wrinkle formation on the surface of the treated film is suppressed.
When the undried film is immersed in water, the contact ratio of water is 10 parts by weight or more, preferably 30 parts by weight or more with respect to 1 part by weight of the undried film. In order to minimize the amount of residual solvent in the resulting proton conducting membrane, it is preferable to maintain a contact ratio as large as possible. It is also effective to reduce the amount of residual solvent in the resulting proton conducting membrane by changing the water used for immersion or allowing it to overflow so that the organic solvent concentration in the water is always kept below a certain level. is there. In order to suppress the in-plane distribution of the amount of the organic solvent remaining in the proton conducting membrane, it is effective to homogenize the concentration of the organic solvent in water by stirring or the like.

  The temperature of water when the undried film is immersed in water is preferably in the range of 5 to 80 ° C. The higher the temperature, the faster the replacement rate of the organic solvent and water, but the greater the amount of water absorbed by the film, so there is a concern that the surface state of the proton conducting membrane obtained after drying will be rough. Usually, a temperature range of 10 to 60 ° C. is convenient because of the replacement speed and ease of handling.

The immersion time is usually in the range of 10 minutes to 240 hours, although depending on the initial residual solvent amount, contact ratio, and treatment temperature. Preferably, it is in the range of 30 minutes to 100 hours.
When the undried film is immersed in water and dried as described above, a proton conductive membrane with a reduced amount of residual solvent is obtained. The residual amount of the proton conductive membrane thus obtained is usually 5% by weight or less. It is.

Further, depending on the immersion conditions, the amount of residual solvent in the obtained proton conducting membrane can be set to 1% by weight or less. As such a condition, for example, the contact ratio between the undried film and water is 50 parts by weight or more of water with respect to 1 part by weight of the undried film.
There is a method of setting the immersion time at 10 ° C. for 10 ° C.

  After immersing the undried film in water as described above, the film is dried at 30-100 ° C, preferably 50-80 ° C, for 10-180 minutes, preferably 15-60 minutes, and then at 50-150 ° C. The proton conducting membrane of the present invention can be obtained by vacuum drying under reduced pressure of 500 mmHg to 0.1 mmHg for 0.5 to 24 hours.

The proton conductive membrane of the present invention obtained by the above production method has a dry film thickness of usually 10 to 100 μm, preferably 20 to 80 μm.
The proton conductive membrane for direct methanol fuel cell of the present invention may contain an anti-aging agent, preferably a hindered phenol compound having a molecular weight of 500 or more, and the durability as a proton conducting membrane by containing the anti-aging agent. Can be further improved.

As a hindered phenol compound having a molecular weight of 500 or more that can be used in the present invention, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) proonate] (trade name: IRGANOX 245) 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 259), 2,4-bis- (n- Octylthio) -6- (4-hydroxy-3,
5-Di-t-butylanilino) -3,5-triazine (trade name: IRGANOX 565), pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (product) Name: IRGANOX 1010), 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 1035), octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate) (trade name: IRGANOX 1076), N, N-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) ( IRGAONOX 1098) 1,3,5-trimethyl-2,4,6
-Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (trade name: IRGANOX 1330), tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate ( Product name: IRGANOX 3114), 3,9-bis [2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4, 8,10-tetraoxaspiro [5.5] undecane (trade name: Sumilizer GA-80).

  In the present invention, the hindered phenol compound having a molecular weight of 500 or more is preferably used in an amount of 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyarylene block copolymer.

  The proton conductive membrane for direct methanol fuel cell of the present invention using a polyarylene block copolymer has an improved methanol crossover, reduces the electrical resistance of the membrane, and suppresses dimensional changes due to immersion in aqueous methanol. Fuel cell for household power supply, fuel cell vehicle, fuel cell for mobile phone, fuel cell for personal computer, fuel cell for portable terminal, fuel cell for digital camera, portable CD, MD fuel cell, It can be suitably used for applications such as a headphone stereo fuel cell, a pet robot fuel cell, an electric assist bicycle fuel cell, and an electric scooter fuel cell. The proton conductive membrane of the present invention is a proton that can be used for, for example, an electrolyte for a primary battery, an electrolyte for a secondary battery, a polymer solid electrolyte for a fuel cell, a display element, various sensors, a signal transmission medium, a solid capacitor, an ion exchange membrane, and the like. It can be used for a conductive film.

As described above in detail, according to the present invention, it is possible to provide a proton conductive membrane for a direct methanol fuel cell having a low electrical resistance of the membrane, a low water / methanol permeability, and a low volume change rate with respect to an aqueous methanol solution, Its industrial value is tremendous. The proton conducting membrane of the present invention can be suitably used for direct methanol fuel cells, and high output and good durability performance can be expected.

(Direct methanol fuel cell)
Next, the configuration of the direct methanol fuel cell will be described. FIG. 1 is a configuration diagram of the direct methanol fuel cell.
As shown in FIG. 1, the direct methanol fuel cell includes a fuel electrode 1, an electrolyte membrane 2 in contact with 1, an air electrode 3 provided opposite to the fuel electrode 1 and in contact with the electrolyte membrane 2, and a fuel electrode. 1 and an external circuit 4 connected to the air electrode 3. The electrolyte membrane 2 is made of the proton conducting membrane.

  The direct methanol fuel cell includes a first flow path 11, a second flow path 12, a third flow path 13, and a fourth flow path 14. A methanol aqueous solution as a fuel is supplied to the first flow path 11 (A in FIG. 1). From the second flow path 12, an aqueous solution containing carbon dioxide (including carbon dioxide) is discharged (B in FIG. 1). Air containing oxygen is supplied to the third flow path 13 (C in FIG. 1). From the fourth flow path 14, the gas (including water) with reduced oxygen is discharged (D in FIG. 1).

  Here, the reaction occurring in the direct methanol fuel cell will be described. In the fuel electrode 1, methanol and water react to generate carbon dioxide, hydrogen ions, and electrons. Hydrogen ions pass through the electrolyte membrane 2 toward the air electrode 3, and electrons flow through the external circuit 4. That is, the following reaction occurs at the fuel electrode 1.

CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻
In the air electrode 3, oxygen, hydrogen ions from the fuel electrode 1, and electrons from the external circuit 4 react to become water. That is, the following reaction occurs at the air electrode.
(3/2) O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O
The overall reaction can be expressed as:
CH ₃ OH + (3/2) O ₂ → CO ₂ + 2H ₂ O
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
[Example]
In the examples, the sulfonic acid equivalent, molecular weight, membrane electrical resistance, volume change rate and methanol permeability were determined as follows.

1. Sulfonic acid equivalent (ion exchange capacity: IEC)
Wash the resulting polyarylene block copolymer having an alkylsulfonic acid group until the washing water becomes neutral, thoroughly wash with the exception of free remaining acid, and after drying, weigh a predetermined amount. Then, titration was performed using a standard solution of NaOH using phenolphthalein dissolved in a mixed solvent of THF / water as an indicator, and the sulfonic acid equivalent (meq / g) was determined from the neutralization point.

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

3. Measurement of electrical resistance of membrane The electrical resistance of the proton conducting membrane was obtained by sandwiching the membrane from above and below with a conductive carbon plate through sulfuric acid having a concentration of 1 mol / L and measuring the AC resistance between the plates. At this time, the membrane is sandwiched from above and below by a 0.5 mm thick silicone rubber having a hole of an appropriate size for contacting with sulfuric acid, so that sulfuric acid is prevented from flowing out and the membrane does not directly contact the carbon plate. Can be kept. Using the resistance value (blank value) of the system when no membrane is present and the value of the contact area between the membrane and sulfuric acid, the electrical resistance of the membrane is calculated from the following equation.

Electric resistance of the film (Ω · cm ² ) = (resistance value R (Ω) between the carbon plates when the film is sandwiched−blank value (Ω)) × contact area A (cm ² )
The measurement was performed at room temperature, and the temperature range was 20 ° C to 30 ° C. The fluctuation range of the measured value of electrical resistance due to temperature fluctuation in the temperature range was not more than plus or minus 0.01 (Ω · cm ² ).

When considering practicality as a DMFC, it can be said that the electrical resistance of the film measured under the above conditions should be 0.4 (Ω · cm ² ) or less, and more specifically 0.3 (Ω · cm ^2). The following are preferred.

4). Solubility and swelling in methanol aqueous solution)
Resistance evaluation with respect to the methanol aqueous solution was performed by immersing the proton conducting membrane in a methanol aqueous solution having a predetermined concentration (10 wt%) at room temperature for 20 hours, and calculating the volume change rate before and after immersion. The evaluation film was prepared by casting a film from NMP 25 wt% solution by casting, drying at 150 ° C., and then removing the solvent by washing with water and cutting to 20 × 30 mm.

Volume change rate (%) = ((area after immersion) / (area before immersion)) × (film thickness after immersion) / (film thickness before immersion)) × 100
In consideration of practicality as a DMFC, the area change rate of the film measured under the above conditions is preferably 120% or less.

5. Methanol permeability Methanol permeability was evaluated by setting a proton conductive membrane sample cut into a predetermined cell with a diameter of 60 mm, supplying 10% by weight or 30% by weight aqueous methanol solution from the front side, and reducing the pressure from the back side. The permeation liquid was trapped with liquid nitrogen and recovered by an osmotic vaporization method (pervaporation method). The temperature was 25 ° C., and the characteristics were evaluated from the permeate amount under reduced pressure (total flux), the methanol permeation amount (methanol flux), and the separation coefficient indicating the selective permeability between methanol and water. The total flux, methanol flux, and separation factor were determined by the following equations. The smaller the values of the total flux, methanol flux, and separation factor, the better the characteristics. The permeate refers to the permeate collected with a liquid nitrogen trap, and the permeate concentration refers to the weight concentration of methanol in the permeate.

Total flux (g / (m ² · h)) = (permeate weight (g) / recovery time (h) / sample area (m ² ))
Methanol flux (g / (m ² · h)) = total flux (g / (m ² · h)) × permeate concentration (%)
Separation factor = (permeate concentration (%) / (100−permeate concentration (%))) / (feed solution concentration (%) / (100−feed solution concentration (%)))
The total flux is the total permeate amount of methanol and water. The smaller this value, the more effective the permeation suppression of water / methanol, and it is required to be 2500 or less, preferably 2000 or less. When considering practicality as DMFC, the methanol flux measured under the above conditions using a 10% by weight aqueous methanol solution needs to be 240 or less, and preferably 220 or less. The separation factor is required to be 2.0 or less as a minimum condition.
Synthesis example 1
Preparation of aromatic compound (oligomer (A)) 4,4′-difluorobenzophenone was added to a 2 L three-necked flask equipped with a stirrer, thermometer, condenser, Dean-Stark tube, and nitrogen-introduced three-way cock. 103.90 g (0.476 mol), 4-chloro-4'-fluorobenzophenone 21.23 g (0.
090 mol), resorcinol 57.68 g (0.524 mol), potassium carbonate 86.87 g (0.629 mol), N, N-dimethylacetamide (DMAc) 625 m
L and 250 mL of toluene were added, heated in an oil bath, and reacted at 140 ° C. with stirring under a nitrogen atmosphere. When water produced by the reaction was azeotroped with toluene and reacted while being removed from the system with a Dean-Stark tube, almost no water was produced in about 3 hours. Subsequently, most of the toluene was removed while gradually raising the reaction temperature to 150 ° C., and the reaction was continued for 5 hours. Then, 12.29 g (0.052 mol) of 4-chloro-4′-fluorobenzophenone was added, and an additional 150 The reaction was carried out at 2 ° C for 2 hours. The resulting reaction solution was allowed to cool, and then a by-product inorganic compound precipitate was removed by filtration, and the filtrate was poured into 3 L of methanol. The precipitated product was collected by filtration, dried, and then dissolved in 500 mL of DMAc. This solution was added to 3 L of methanol for reprecipitation, and 129.4 g of the desired compound (
Yield 92%) was obtained.

  The number average molecular weight in terms of polystyrene determined by GPC (THF solvent) of the obtained polymer was 5000. Moreover, the obtained polymer was soluble in NMP and THF, and Tg was 130 degreeC.

  The resulting polymer has the following formula (16):

It is presumed to have a structure represented by
Synthesis example 2
Preparation of aromatic compound (oligomer (B)) 4,4′-difluorobenzophenone was added to a 2 L three-necked flask equipped with a stirrer, thermometer, condenser, Dean-Stark tube, and nitrogen-introduced three-way cock. 103.90 g (0.476 mol), 4-chloro-4′-fluorobenzophenone 21.23 g (0.0
90 mol), resorcinol 51.91 g (0.471 mol), 9,9-bis (4-hydroxyphenyl) fluorene 18.35 g (0.052 mol), potassium carbonate 86.87 g (0.629 mol), DMAc 556 mL, and toluene 222 mL was added, heated in an oil bath, and reacted at 140 ° C. with stirring under a nitrogen atmosphere. When water produced by the reaction was azeotroped with toluene and reacted while being removed from the system with a Dean-Stark tube, almost no water was produced in about 3 hours. Subsequently, most of the toluene was removed while gradually raising the reaction temperature to 150 ° C., and the reaction was continued for 5 hours. After that, 12.29 g (0.052 mol) of 4-chloro-4′-fluorobenzophenone was added, and an additional 150 The reaction was carried out at 2 ° C. for 2 hours. The resulting reaction solution was allowed to cool, and then the by-product inorganic compound precipitate was removed by filtration, and the filtrate was poured into 3 L of methanol. The precipitated product was collected by filtration, dried, and then dissolved in 500 mL of DMAc. This solution was added to 3 L of methanol and reprecipitated to obtain 137.9 g (yield 90%) of the target compound.

  The number average molecular weight in terms of polystyrene determined by GPC (THF solvent) of the obtained polymer was 5000. Moreover, the obtained polymer was soluble in NMP and THF, and Tg was 140 degreeC.

  The resulting polymer has the following formula (17):

It is presumed to have a structure represented by In Formula (17), m and n are positive integers.
Synthesis example 3
Synthesis of benzophenone derivative (compound (A ₁ )) (i) Synthesis of 2,5-dichloro-4′-hydroxybenzophenone 64.9 g (600 mmol) of anisole and 480 mL of dichloromethane were attached with a stirrer, a nitrogen introducing tube and a dropping funnel. Into a 2 L three-necked flask and cooled to 10 ° C. with an ice bath, 80 g (600 mmol) of aluminum chloride was added. Next, 125.7 g (600 mmol) of 2,5-dichlorobenzoic acid chloride was slowly dropped from the dropping funnel. After completion of dropping, 80 g (600 mmol) of aluminum chloride was added. Thereafter, the temperature was returned to room temperature and stirring was continued for 12 hours.

Thereafter, the reaction solution was poured into 2 L of ice water containing 300 mL of concentrated hydrochloric acid, and the separated organic layer was extracted with a 10% aqueous sodium hydroxide solution. On the other hand, the aqueous layer was neutralized with hydrochloric acid, and the precipitated solid was extracted with 2 L of ethyl acetate. The solvent was distilled off, and the resulting solid was recrystallized with a mixed solvent of ethyl acetate and n-hexane to obtain 136.3 g (yield 85%) of 2,5-dichloro-4′-hydroxybenzophenone (compound (A ₁ ')).

(Ii) Synthesis of 2,5-dichloro-4 ′-(tetrahydro-2-pyranyloxy) benzophenone (compound (A ₁ )) 2,5-dichloro-4′-hydroxybenzophenone which is the compound (A ₁ ) 7g
(100 mmol) 2H-dihydropyran 100 g (1200 mmol) and toluene 100 mL were placed in a flask, and 1.5 g of cation exchange resin (Amberlyst 15) was added to the flask while stirring, and stirring was continued at room temperature for 5 hours. The cation exchange resin was removed by filtration. Subsequently, the obtained filtrate was washed with an aqueous sodium hydroxide solution and brine, dried over magnesium sulfate, and then the solvent was distilled off. The obtained solid was recrystallized from toluene to obtain 16.4 g (yield 47%) of 2,5-dichloro-4 ′-(tetrahydro-2-pyranyloxy) benzophenone (compound (A ₁ )). Moreover, the said process (i) and (ii) in this synthesis example is shown to following formula (18).

Synthesis example 4
2,5-Dichloro-4 ′-(tetrahydro-2) obtained in Synthesis Example 3 which is the compound (A ₁ )
-Pyranyloxy) benzophenone 32.40 g (92.24 mmol), oligomer (A) obtained in Synthesis Example 1 38.82 g (7.76 mmol), bis (triphenylphosphine) nickel dichloride 1.96 g (3.00 mmol), Sodium iodide 1.95 g (13.00 mmol), triphenylphosphine 10.49 g (40 mmol)
Zinc (15.69 g, 240 mmol) was placed in a 500 mL flask equipped with a stirring blade, a thermometer, and a nitrogen introduction tube, and dried in vacuo. After replacing the inside of the flask with dry nitrogen, 178 mL of DMAc was added to initiate polymerization. During the polymerization, the temperature of the reaction solution was controlled to be in the range of 70 to 90 ° C. After 3 hours, 200 mL of THF was added for dilution, and the insoluble portion was filtered to obtain a polymer solution filtrate.

  The filtrate of this polymer solution was poured into 1.5 L of methanol containing 10 vol% concentrated hydrochloric acid to precipitate the polymer. Next, after separating the precipitate by filtration, the obtained solid was dried to obtain 50.3 g of a polymer (compound (A-1)) having a hydroxyl group. In addition, the said process in this synthesis example is shown in following formula (19). In Expression (19), d, e, and f are positive integers.

Synthesis of polyarylene (1) having a sulfonic acid group 20.0 g of the compound (A-1) was added to 147 mL of DMAc, and the mixture was stirred and dissolved while heating at 100 ° C. Next, 0.78 g of lithium hydride (3 equivalents with respect to the hydroxyl group of phenol) was added and stirred for 2 hours. Subsequently, 6.00 g of propane sultone (B-1) (1.5 equivalents relative to the hydroxyl group of phenol) was added and reacted for 8 hours. Next, the insoluble part of the reaction solution was filtered, and then poured into 1N hydrochloric acid to precipitate the polymer. The precipitated polymer was washed with 1N hydrochloric acid and then washed with distilled water until the pH became neutral. This polymer was dried at 75 ° C. to obtain 21.2 g of a polyarylene (compound (1)) having a powdered sulfonic acid group. Moreover, the said process in this synthesis example is shown to following formula (20). In Expression (20), d, e, and f are positive integers.

Synthesis example 5
In Synthesis Example 4, the reaction was conducted in the same manner as in Synthesis Example 4 except that 6.69 g of butane sultone (B-2) was used instead of 6.00 g of propane sultone (B-1). As a result, 20.8 g of polyarylene (compound (2)) was obtained. Moreover, the said process in this synthesis example is shown to following formula (21). In the formula (21), d, e, and f are positive integers.

Synthesis Example 6
In Synthesis Example 5, the reaction was performed in the same manner as in Synthesis Example 5 except that 38.82 g of the oligomer (B) obtained in Synthesis Example 2 was used instead of 38.82 g of the oligomer (A) obtained in Synthesis Example 1. Then, 20.8 g of polyarylene (compound (3)) having a powdery sulfonic acid group was obtained. Moreover, the said process in this synthesis example is shown to following formula (22). In Expression (22), d, e, f, and g are positive integers.

Synthesis example 7
In Synthesis Example 6, 2,5-dichloro-4 ′-(tetrahydro-2) which is the compound (A ₁ )
Instead of 32.40 g (92.2 mmol) of pyranyloxy) benzophenone and 38.82 g (7.7 mmol) of the oligomer (B) obtained in Synthesis Example 2, 2,5-dichloro-4 which is the compound (A ₁ ) '-(Tetrahydro-2-pyranyloxy) benzophenone 32
. The reaction was carried out in the same manner as in Synthesis Example 6 except that 88 g (93.6 mmol) and 31.84 g (6.4 mmol) of the oligomer (B) obtained in Synthesis Example 2 were used, and powdered polyarylene (compound ( 4)) 20.8 g was obtained.

[Example 1]
The polymer obtained in Synthesis Example 4 was dissolved in NMP to form a 25 wt% solution, and a film was formed using a bar coater. After drying at 150 ° C., the solvent was removed by washing with water to obtain a film. The film thickness measured using a dial gauge was 45 μm.

[Example 2]
The polymer obtained in Synthesis Example 5 was dissolved in NMP to form a 25 wt% solution, and a film was formed using a bar coater. After drying at 150 ° C., the solvent was removed by washing with water to obtain a film. The film thickness measured using a dial gauge was 45 μm.

[Example 3]
The polymer obtained in Synthesis Example 6 was dissolved in NMP to form a 25 wt% solution, and a film was formed using a bar coater. After drying at 150 ° C., the solvent was removed by washing with water to obtain a film. The film thickness measured using a dial gauge was 35 μm.

[Example 4]
The polymer obtained in Synthesis Example 7 was dissolved in NMP to form a 25 wt% solution, and a film was formed using a bar coater. After drying at 150 ° C., the solvent was removed by washing with water to obtain a film. The film thickness measured using a dial gauge was 40 μm.

About the film obtained in Examples 1-4, each measurement of the electrical resistance of an above-described film | membrane, the area change rate with respect to methanol aqueous solution, and methanol permeability was performed.
[Comparative Example 1]
For Nafion 117 (trademark) (180 μm thick), the same measurements as those of the films obtained in Examples 1 to 4 were performed.

  The results are shown in Table 1.

  As shown in Table 1, the proton conductive membrane obtained in the present invention was a good characteristic that all of Examples 1 to 4 greatly exceeded the comparative example in each physical property. Since the membrane of the present invention does not have a perfluoro structure with weak methanol resistance like the Nafion membrane of the comparative example, the methanol resistance is high, the methanol flux and the separation factor are greatly improved, and the main chain skeleton has an aromatic ring. It is considered that the area change rate characteristics are also improved.

1 is a schematic configuration diagram illustrating an example of a direct methanol fuel cell.

Explanation of symbols

1 Fuel electrode 2 Electrolyte membrane 3 Air electrode 4 External circuit

Claims (4)

  A block copolymer comprising a repeating unit containing an ion conductive group and a repeating unit not containing an ion conductive group, wherein the ion conductive group is an alkylsulfonic acid group. A proton conductive membrane for a direct methanol fuel cell, comprising: In the polyarylene block copolymer, the repeating unit containing an ion conductive group is a repeating unit represented by the following general formula (1), and the repeating unit not containing an ion conductive group is represented by the following general formula (2). The proton conducting membrane for a direct methanol fuel cell according to claim 1, wherein the proton conducting membrane is a repeating unit represented by the formula:

[In the formula (1), X and Y represent a divalent organic group or a single bond, Z represents an oxygen atom or a sulfur atom, R represents a group consisting of a hydrogen atom, a fluorine atom, an alkyl group and a fluorine-substituted alkyl group. At least one atom or group selected from the above, a is an integer of 1 to 20, n is an integer of 1 to 5, and m is an integer of 0 to 10; ]

[In formula (2), R ^{1 to} R ⁸ may be the same or different from each other, and are selected from the group consisting of a hydrogen atom, a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, an allyl group, an aryl group, and a cyano group. And at least one atom or group, W represents a divalent electron-withdrawing group or single bond, T represents a single bond, a divalent electron-withdrawing group, a divalent electron-donating group, or the following general formula: (3) represents a divalent group represented by (4), p represents a positive integer, and R ^{1 to} R ⁸ , W and T are independent of each other for each of p repeating units constituting the block. It is. ]

[In the formulas (3) and (4), R ^{9 to} R ²⁰ may be the same or different from each other, and are a hydrogen atom, a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, an allyl group, an aryl group, a cyano group, or 2 Represents at least one atom or group selected from the group consisting of valent electron-withdrawing groups, K represents a single bond or a divalent electron-donating group, J represents a single bond, an alkylene group, or a fluorine-substituted alkylene group. , aryl substituted alkylene group, alkenylene group, alkynylene group, an arylene group, a fluorenylidene group, -O -, - S -, - CO -, - CONH -, - COO -, - SO- or -SO ₂ - shows a block K, l, m, i, X, and T are independent of each other for each of the p repeating units that constitute. ].   The polyarylene block copolymer has a repeating unit of 0.1 to 99.9 mol% represented by the general formula (1) and a repeating unit of 0.1 to 99.99 represented by the general formula (2). The proton conducting membrane for a direct methanol fuel cell according to claim 2, comprising 9 mol%.   4. The proton conductive membrane for a direct methanol fuel cell according to claim 1, wherein the polyarylene block copolymer has an ion exchange capacity of 0.3 to 5.0 meq / g.

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