JP2011084728A - Polyelectrolyte and utilization thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrocarbon-based polyelectrolyte excellent in processability, capable of efficiently retaining water even in a water-deficient condition, capable of assuring proton conduction, and capable of providing high-precision circuit drawing for inexpensively and simply making a fine-pitched electronic circuit. <P>SOLUTION: The polyelectrolyte is a copolymer containing units having a high sulfonic acid group introduction ratio and units having a low sulfonic acid group introduction rate, wherein the units having the high sulfonic acid group introduction ratio contains structures represented by formula (1) (wherein X<SP>1</SP>is O, S, NH, or a direct bond) and/or formula (2) (wherein X<SP>1</SP>is O, S, NH, or a direct bond). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a polymer electrolyte suitable for a solid polymer fuel cell, a polymer electrolyte membrane using the polymer electrolyte, a membrane / electrode assembly, and a fuel cell including these.

In recent years, development of highly efficient and clean energy sources has been demanded from the viewpoint of environmental problems such as global warming. Fuel cells are attracting attention as one candidate for this. A fuel cell directly supplies power by supplying a fuel such as hydrogen gas or methanol and an oxidant such as oxygen to electrodes separated by an electrolyte, while oxidizing the fuel on the one hand and reducing the oxidant on the other. is there. Among the fuel cell materials described above, one of the most important members is an electrolyte. Various electrolyte membranes that separate the electrolyte fuel and oxidant have been developed so far, but in recent years, they are composed of polymer compounds containing proton conductive functional groups such as sulfonic acid groups. The development of polymer electrolytes is thriving. Such a polymer electrolyte is used as a raw material for electrochemical elements such as a humidity sensor, a gas sensor, and an electrochromic display element, in addition to the solid polymer fuel cell. Among these polymer electrolyte utilization methods, in particular, polymer electrolyte fuel cells are expected as one of the pillars of new energy technology. For example, a polymer electrolyte fuel cell using an electrolyte membrane made of a polymer compound having a proton-conducting functional group has features such as operation at a low temperature and reduction in size and weight. Application to consumer cogeneration systems and consumer small portable devices is under consideration.

As an electrolyte membrane used in a polymer electrolyte fuel cell, there is a styrene-based cation exchange membrane developed in the 1950s. However, the fuel cell has poor stability under a fuel cell operating environment and has a sufficient lifetime. Has not yet been manufactured. On the other hand, as an electrolyte membrane having practical stability, a perfluorocarbon sulfonic acid membrane represented by Nafion (registered trademark) has been widely studied. Perfluorocarbon sulfonic acid membranes are said to have high proton conductivity and excellent chemical stability such as acid resistance and oxidation resistance. However, Nafion (registered trademark) has a drawback that it is very expensive because of the high raw materials used and the complicated manufacturing process. In addition, it has been pointed out that it is deteriorated by hydrogen peroxide generated by the electrode reaction and by-product hydroxy radical. Furthermore, due to its structure, there is a limit to the introduction of sulfonic acid groups that are proton conducting groups.

Against this background, development of hydrocarbon electrolyte membranes is expected again. The reason for this is that the hydrocarbon electrolyte membrane is easy to have a variety of chemical structures, the range of introduction of proton conducting groups such as sulfonic acid groups can be adjusted widely, compounding with other materials, introduction of crosslinking, etc. This is because there is a feature that is relatively easy.

For example, in Non-Patent Document 1, poly (2,6-diphenyl-4-phenylene oxide) (hereinafter abbreviated as PPPO) having a structure containing many phenyl groups easily sulfonated in the molecule and having high-temperature stability. And a polyelectrolyte (sulfonated poly (2,6-diphenyl-4-phenyl) having an ion exchange capacity (hereinafter abbreviated as IEC) of 0.7 to 2.8 meq / g, which is obtained by sulfonation treatment. Phenylene oxide)) is illustrated. However, in this document, it is shown that when the IEC is 2.6 meq / g or more, it is dissolved in water, which is not suitable for an electrolyte membrane for a fuel cell.

Patent Document 1 exemplifies a homopolymer and a random copolymer containing a benzonitrile structure, but in an electrolyte membrane using a random copolymer or a homopolymer, a microphase separation state effective for proton conductivity at low humidity It is known that it is difficult to become.

Patent Document 2 exemplifies a block copolymer having a block in which a sulfonic acid group is introduced and a block in which a sulfonic acid group is not substantially introduced. However, both the hydrophilic part and the hydrophobic part to be used must be synthesized by different synthesis methods, and the monomers that can be used to suppress side reactions in the polymerization of the polyparaphenylene units used are limited. Therefore, synthesis other than those exemplified is difficult. Therefore, like Nafion (registered trademark), since it goes through a complicated manufacturing process, there is a disadvantage that it is very expensive.

JP 2004-244437 A JP 2001-250567 A

New Materials For Fuel Cell And Modern Battery Systems II 794-78

An object of the present invention is to provide a hydrocarbon-based polymer electrolyte that is excellent in processability, can efficiently retain water even in a state of little water, and can ensure proton conduction.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have made a specific structure at a site where the introduction rate of sulfonic acid groups is high while having sulfonic acid groups advantageous for proton conductivity in the entire polymer electrolyte. When the partial sulfonic acid group density was increased by inclusion, it was found that the proton conductivity was excellent in a situation with little moisture, and the present invention was completed.

That is, the present invention is a block copolymer including a unit having a high sulfonic acid group introduction rate and a unit having a low sulfonic acid group introduction rate, and the unit having a high sulfonic acid group introduction rate is represented by the following formula (1):

(In formula (1), X ¹ represents O, S, NH or a direct bond.)
And / or the following formula (2):

(In formula (2), X ¹ is the same as above.)
It is a polymer electrolyte containing the structure shown by these.

The unit having a high sulfonic acid group introduction rate is represented by the following formula (3):

(In formula (3), X ¹ is the same as above. X ² represents O, S, NH, CO, SO ₂ , C (CF ₃ ) ₂ , isopropylidene, fluorenylidene or a direct bond, R ¹ represents fluorine, chlorine, bromine, alkyl groups having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, indicates a heteroaromatic ring or an alkoxy group having 1 to 10 carbon atoms, containing nitrogen at 1 to 9 carbon atoms, ^{R 1} is When there are a plurality, they may be the same or different, a, b, c and d each represent 0 or 1, e represents any one of 0 to 4, and f represents any one from 0 to 6. X ¹ , X ² , R ¹ , e, and f may be the same or different when there are a plurality of them, and Y represents the following formula (4):

Or the following formula (5):

Indicates. It is preferable to include a structure in which a sulfonic acid group is introduced into the structure represented by

The unit having a high introduction rate of the sulfonic acid group has a structure in which a and d are 1, b and c are 0, and X ¹ is O in the above formula (3), and / or in the above formula (3), a and It is preferable to include a structure in which a sulfonic acid group is introduced into a structure in which d is 0, b and c are 1, and X ¹ is O. Specifically, the following formula (6):

(In formula (6), X ² is the same as above. R ² represents fluorine, chlorine, bromine, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. In some cases, they may be the same or different. G represents 0 to 4, and e is the same as above.)
And / or the following formula (7):

(In formula (7), X ² is the same as above. R ² is the same as above. H is 0 to 4 and f is the same as above.)
It is preferable to include a structure in which a sulfonic acid group is introduced into the structure represented by

It is preferable that 45 to 80% of the aromatic rings contained in the unit having a high sulfonic acid group introduction rate have a sulfonic acid group.

The unit having a low introduction rate of the sulfonic acid group is represented by the following formula (8):

(In the formula (8), X ³ represents CO or SO _2. Z ¹ represents hydrogen, a metal ion, or an ammonium ion. I represents 0 to 2, and R ³ may be substituted with fluorine. A good alkyl group having 1 to 10 carbon atoms, CN, COZ ² , or SO ₂ Z ² , wherein Z ² is an optionally substituted alkyl group having 1 to 10 carbon atoms or aryl having 6 to 12 carbon atoms In some cases, they may be the same or different, e represents a value of 0 to 4, and j represents a value of 0 to 1. However, when i = 1, the sum of j Is a value less than 2.)
It is preferable that the structure shown by these is included.

The unit having a low introduction rate of the sulfonic acid group preferably includes a structure in which e is 0, i is 1 and j is 0 in the above formula (8), specifically, the following formula (9):

(In formula (9), X ³ is the same as above.)
It is preferable that the structure shown by these is included.

The polymer electrolyte of the present invention includes the polymer electrolyte.

The membrane electrode assembly of the present invention includes the polymer electrolyte membrane.

The polymer electrolyte fuel cell of the present invention includes the polymer electrolyte membrane and / or the membrane electrode assembly.

The polymer electrolyte of the present invention is excellent in processability, and can have excellent proton conductivity particularly in a situation where moisture is low.

1 is a structural view of a cross section of a main part of a polymer electrolyte fuel cell using a polymer electrolyte membrane of the present invention.

An embodiment of the present invention will be described as follows. The present invention is not limited to the following description.

<Polymer electrolyte>
The block copolymer which is the polymer electrolyte of the present invention contains a unit having a high sulfonic acid group introduction rate and a unit having a low sulfonic acid group introduction rate, and the unit having a high sulfonic acid group introduction rate is represented by the following formula (1). Alternatively, it is characterized in that the ratio of the aromatic ring which is difficult to introduce a sulfonic acid group contained in a unit containing the structure represented by (2) and having a high sulfonic acid group introduction rate is reduced. Due to this feature, excellent proton conductivity can be exhibited.

(In formula (1), X ¹ represents O, S, NH, or a direct bond.)

(In formula (2), X ¹ is the same as above.)
A block copolymer refers to a unit in which units having different properties are bonded to each other and has a property different from that of a homopolymer comprising the original unit. The block copolymer of the present invention may be in the form of having each unit in the main chain, or in the form of having one unit as the main chain and the other unit in the form of a side chain block. In addition, the unit may have both units in the main chain and the side chain. Here, the unit basically refers to an assembly that can be expressed as a repetition of a certain component as a repeating unit, or a modification of the assembly.

Here, the sulfonic acid group introduction rate refers to the ratio of aromatic rings into which sulfonic acid groups have been introduced among the aromatic rings contained in the repeating units forming each unit. Here, the naphthalene ring is counted as one of the aromatic rings.

Here, the number of aromatic rings contained in the unit is determined by the structure of the polymer. The polymer structure is determined by the raw materials used for the synthesis. When the raw materials used for the synthesis are, for example, an aromatic dihalide compound and an aromatic diol compound, the fluorine of the aromatic dihalide compound and the hydrogen of the hydroxyl group of the aromatic diol compound are lost, and the respective sites are bonded. Therefore, the number of aromatic rings contained in the polymer unit synthesized from these is equal to the total number of aromatic rings of these raw material components.

Further, it is generally known that the number of aromatic rings into which sulfonic acid groups contained in the unit are introduced varies depending on the method of introducing sulfonic acid groups. For example, as a general method for synthesizing and sulfonating a polymer, when sulfonating with sulfuric acid having a concentration of 80% or more or a chlorosulfonic acid solution, the number of aromatic rings into which sulfonic acid groups are introduced is as follows. become that way.

In the case of sulfonation with sulfuric acid having a concentration of 80% or more or a chlorosulfonic acid solution, aromatic rings excluding an aromatic ring having two or more substituents and an aromatic ring bonded to an electron withdrawing group are sulfonated. Therefore, in the repeating unit structure of the unit, the number of aromatic rings other than the aromatic ring bonded to the aromatic ring having two or more substituents and the electron withdrawing group can be treated as the number of aromatic rings into which the sulfonic acid group is introduced.

In addition, an aromatic ring in which a sulfonic acid group (sulfonic acid group derivative) has already been introduced before sulfonation is included, such as when a unit is synthesized using an aromatic compound having a sulfonic acid group derivative. Are treated as aromatic rings contained in the repeating unit forming the unit.

The number of aromatic rings into which sulfonic acid groups are introduced can be obtained by calculation by obtaining the ion exchange capacity of each unit.

Specifically, the unit having a high introduction rate of the sulfonic acid group preferably has 35% or more of all aromatic rings contained in the repeating units forming the unit, and has 40% or more. Is more preferably 45% or more.

On the other hand, the unit having a low sulfonic acid group introduction rate is specifically preferably less than 35% of all aromatic rings having a sulfonic acid group among the total aromatic rings contained in the repeating units forming the unit. % Or less is more preferable, and 20% or less is more preferable.

The main chain skeleton of a unit having a high sulfonic acid group introduction rate preferably has many aromatic rings bonded to an electron donating functional group. For example, a sulfonic acid group is introduced into the structure represented by the following formula (3). Main chain skeleton.

(In formula (3), X ¹ is the same as above. X ² represents O, S, NH, CO, SO ₂ , C (CF ₃ ) ₂ , isopropylidene, fluorenylidene or a direct bond, R ¹ represents fluorine, Indicate chlorine, bromine, alkyl group having 1 to 10 carbon atoms, aryl group having 6 to 12 carbon atoms, heteroaromatic ring containing 1 to 9 carbon atoms and nitrogen, or alkoxy group having 1 to 10 carbon atoms Each may be the same or different, a, b, c and d each represent 0 or 1, e represents one of 0 to 4, and f represents one of 0 to 6. X ¹ , X ² , R ¹ , e, and f may be the same or different when there are several, and Y represents the following formula (4) or (5).

From the viewpoint of increasing the sulfonic acid group density, the main chain skeleton of the unit having a high sulfonic acid group introduction rate has a structure in which b and c are 0, a and d are 1, and X ¹ is O in the above formula (3). And / or the above formula (3) preferably includes a structure in which b and c are 1, a and d are 0, and X ¹ is O. Specifically, the following formula (6) and / or formula ( It is preferable to have a structure in which a sulfonic acid group is introduced into the structure represented by 7).

(In formula (6), X ² is the same as above. R ² represents fluorine, chlorine, bromine, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. In some cases, they may be the same or different. G represents 0 to 4, and e is the same as above.)

(In formula (7), X ² is the same as above. R ² is the same as above. H is 0 to 4 and f is the same as above.)
In particular, it is more preferable that the main chain is formed by a structure in which aromatic rings are ether-bonded to each other, or that the main chain is formed by a structure in which aromatic rings are directly bonded to each other and ether-bonded. In general, an aromatic ring bonded to an electron withdrawing group is less likely to introduce a sulfonic acid group by sulfonation than an aromatic ring to which no electron withdrawing group is bonded. Therefore, when the aromatic ring bonded to the electron withdrawing group is contained, the aromatic ring bonded to the electron withdrawing group excluding the sulfonic acid group derivative is preferably less than 65% of the total aromatic rings contained in the unit. % Or less is more preferable, and 40% or less is more preferable.

Here, the sulfonic acid group derivative protects (temporarily converts to a non-acid) sulfonic acid, such as converting the sulfonic acid of the sulfonic acid group into a sulfonic acid ester or the like. Refers to things.

In the present invention, it is preferable that the main chain skeleton of a unit having a low introduction rate of sulfonic acid group has many aromatic rings bonded to electron-withdrawing functional groups, or has many aromatic rings having substituents. Especially, it is preferable that all the aromatic rings contained in the unit having a low sulfonic acid group introduction rate are bonded to one or more electron-withdrawing functional groups or have one or more substituents.

The main chain skeleton of a unit having a low sulfonic acid group introduction rate may have an aromatic ring bonded to an electron withdrawing group.

As the main chain skeleton of the unit having a low sulfonic acid group introduction rate, for example, one having a main chain skeleton represented by the following formula (8) is preferable.

(In Formula (8), X ³ represents CO or SO ₂ , Z ¹ represents hydrogen, a metal ion, or an ammonium ion, i represents 0 to 2, and R ³ may be substituted with fluorine. A good alkyl group having 1 to 10 carbon atoms, CN, COZ ² or SO ₂ Z ² , wherein Z ² is an optionally substituted alkyl group having 1 to 10 carbon atoms or aryl having 6 to 12 carbon atoms In some cases, they may be the same or different, e represents a value of 0 to 4, and j represents a value of 0 to 1. However, when i = 1, the sum of j Is a value less than 2.)
Among these, from the viewpoint of ease of processing, it is preferable to include a structure in which e is 0, i is 1 and j is 0 in the above formula (8), specifically, a structure represented by the following formula (9). A main chain skeleton having

(In formula (9), X ³ is the same as above.)
The number average molecular weights of the unit having a high sulfonic acid group introduction rate and the unit having a low sulfonic acid group introduction rate are each preferably 200 or more, more preferably 1000 or more, and still more preferably 2000 or more. The upper limit of the number average molecular weight is not particularly set and may be 100,000, but is preferably 60000.

The polymer electrolyte of the present invention is not particularly limited as long as it is a block copolymer including a unit having a high sulfonic acid group introduction rate and a unit having a low sulfonic acid group introduction rate. From the viewpoint of proton conduction and shape stability, it is preferable to contain 10 to 90% by weight of units having a high sulfonic acid group introduction rate.

<Manufacture of polymer electrolyte>
There are mainly two methods for producing the polymer electrolyte of the present invention, and any method can be used.

The first production method is a method in which a unit precursor or a block copolymer is produced and then converted into a sulfonic acid group. However, the unit precursor or block copolymer here is a monomer or oligomer having a sulfonic acid group or a sulfur-containing site such as a sulfide bond, a sulfoxide bond or a sulfone bond that can be converted into a sulfonic acid group by oxidation treatment or the like. Or a polymer and any of these sulfonic acid group derivatives.

The second production method is a method in which a sulfonic acid group is introduced by a sulfonation reaction after producing a unit precursor or a block copolymer having many aromatic rings having no electron withdrawing group. Among these, from the viewpoint of simplifying the production process, it is preferable to form a unit having a high introduction rate of sulfonic acid groups by sulfonation after the block copolymer is produced.

Here, a method for producing a polymer electrolyte by the second production method will be described.

(Synthesis method of unit precursor)
Various methods can be used for synthesizing each unit precursor, such as general polymerization methods (for example, “New Polymer Experimental 3 Polymer Synthesis Method / Reaction (2) Condensation Polymer Synthesis” p. 7-57, p.399-401, (1996) Kyoritsu Publishing Co., Ltd.) can be applied.

The polymerization reaction is preferably performed in an atmosphere that does not contain much oxygen, and is preferably performed in an inert gas atmosphere, such as a nitrogen gas atmosphere or an argon gas atmosphere.

As a preferable polymerization reaction, a polycondensation reaction between a dihalide and a diol having a phenolic hydroxyl group is exemplified.

In order to incorporate the structure of the formula (1) and / or the formula (2) into the unit precursor having a high introduction rate of sulfonic acid group, as the dihalide, for example, 2,3-difluorobenzonitrile, 2,4-difluorobenzonitrile, 2,5-difluorobenzonitrile, 2,6-difluorobenzonitrile, 2,3-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2,5-dichlorobenzonitrile, 2,6-dichlorobenzonitrile, 2, 3-difluoropyridine, 2,4-difluoropyridine, 2,5-difluoropyridine, 2,6-difluoropyridine, 2,3-dichloropyridine, 2,4-dichloropyridine, 2,5-dichloropyridine or 2,6 -It is preferable to use dichloropyridine or the like. Among these, 2,6-difluoropyridine, 2,6-dichloropyridine, 2,6-difluorobenzonitrile, and 2,6-dichlorobenzonitrile are preferable from the viewpoint of obtaining raw materials. These may be used alone or in combination of two or more.

For the synthesis of a unit precursor having a high sulfonic acid group introduction rate, a diol having a phenolic hydroxyl group having at least one aromatic ring and at least two phenolic hydroxyl groups can be used. For example, hydroquinone, resorcinol, catechol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (2-hydroxy-) 5-biphenylyl) propane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2,3-dihydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,5-dihydroxybenzophenone, 3,4-dihydroxybenzophenone, 3,5-dihydroxybenzophenone, 2,2'-dihydroxybenzophenone, 2,3'-dihydroxybenzophenone, 2,4'-dihydroxybenzophenone, 3,3'-dihydroxybenzophenone, 3,4'-dihydroxybenzophenone, 4,4 '-Jihi Roxybenzophenone, 2,3-dihydroxydiphenylsulfone, 2,4-dihydroxydiphenylsulfone, 2,5-dihydroxydiphenylsulfone, 3,4-dihydroxydiphenylsulfone, 3,5-dihydroxydiphenylsulfone, 2,2'-dihydroxydiphenyl Sulfone, 2,3′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 3,3′-dihydroxydiphenylsulfone, 3,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenylsulfone, 2,3 -Dihydroxybiphenyl, 2,4-dihydroxybiphenyl, 2,5-dihydroxybiphenyl, 3,4-dihydroxybiphenyl, 3,5-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 2 , 3'-dihydroxybiphenyl, 2,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl, 9,9-bis (4-hydroxyphenyl) Fluorene, 9,9-bis (4-hydroxy-3-phenylphenyl) fluorene, 9,9-bis (4-hydroxy-3,5-diphenylphenyl) fluorene, 1,2-dihydroxynaphthalene, 1,3-dihydroxy Naphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene 2,7-dihydroxynaphthalene 1,1'-bi-2-naphthol, 1,1'-bi-3-naphthol, 1,1'-bi-4-naphthol, 1,1'-bi-5-naphthol, 1,1'- Bi-6-naphthol, 1,1′-bi-7-naphthol, 1,1′-bi-8-naphthol, 2,2′-bi-1-naphthol, 2,2′-bi-3-naphthol, 2,2'-bi-4-naphthol, 2,2'-bi-5-naphthol, 2,2'-bi-6-naphthol, 2,2'-bi-7-naphthol, 2,2'-bi And -8-naphthol and derivatives thereof. Among these, those that do not contain an electron-withdrawing group are preferable from the viewpoint of increasing the sulfonic acid group introduction rate. These may be used alone or in combination of two or more.

For the synthesis of a unit precursor having a low introduction rate of sulfonic acid group, a dihalide that can be used for the production of the unit having a high introduction rate of sulfonic acid group can be used as a dihalide, and 4,4′-difluorobenzophenone, 4 4,4′-dichlorobenzophenone, 4,4′-difluorodiphenyl sulfone, 4,4′-dichlorodiphenyl sulfone, or structural isomers thereof. An aromatic compound, an aromatic carbonyl compound, an aromatic sulfonyl compound, an aromatic nitrile compound, an aromatic nitro compound, or an aromatic fluoroalkyl compound having two or more halogen substituents on the aromatic ring can also be used.

As the diol, a diol that can be used for the synthesis of a unit precursor having a high sulfonic acid group introduction rate can be used. Of these, hydroquinone, resorcinol, catechol, or an electron-withdrawing group is preferred from the viewpoint of adjusting the sulfonic acid group introduction rate.

In the polycondensation reaction, one or more bases such as metal carbonates such as potassium carbonate, sodium carbonate and calcium carbonate, and metal hydroxides such as potassium hydroxide and sodium hydroxide can be used.

The solvent is not particularly limited as long as polymerization is not prohibited, and examples thereof include heterocyclic compounds (3-methyl-2-oxazolidinone, 1-methyl-2-pyrrolidone (hereinafter abbreviated as NMP), 1,3-dimethyl. -2-imidazolidinone (hereinafter abbreviated as DMI)), cyclic ethers (dioxane, tetrahydrofuran, etc.), chain ethers (diethyl ether, ethylene glycol dialkyl ether, etc.), nitrile compounds (acetonitrile, glutarodinitrile, Methoxyacetonitrile, etc.), aprotic polar substances (dimethyl sulfoxide (hereinafter abbreviated as DMSO), sulfolane, dimethylformamide (hereinafter abbreviated as DMF), dimethylacetamide (hereinafter abbreviated as DMAc)), nonpolar solvents (hexane, cyclohexane, Benzene, toluene, xyle Etc.), halogenated solvents (chlorobenzene, 1,2-dichlorobenzene, etc.), water and the like can be enumerated. From the viewpoint of solubility, heterocyclic compounds such as DMI and NMP and aprotic polar substances such as DMSO, DMF, and DMAc are preferable because of high polymer solubility. Among these, DMI, DMSO, DMF, and DMAc are particularly preferable because of high polymer solubility. These may be used alone or in combination of two or more. Further, a solvent such as cyclohexane or toluene may be used together to remove water generated by polymerization from the system.

The reaction temperature can be appropriately set according to the reactivity and stability of the monomer used in the polymerization reaction, preferably 20 ° C to 300 ° C, more preferably 40 ° C to 250 ° C, and even more preferably 70 ° C. ~ 240 ° C. If the temperature is lower than this range, the reaction rate tends to be remarkably reduced. On the other hand, if the temperature is higher, the decomposition of the monomer and polymer may proceed.

In the polymerization reaction step, it is preferable to perform a stopping operation, which can be performed by cooling, diluting, or adding a polymerization inhibitor. The polymer produced after the polymerization reaction step may be taken out. Further purification steps may be added.

By changing the molar ratio of dihalide and diol having phenolic hydroxyl groups, it is possible to produce halogen-terminated polymers with halogens at both ends, or phenolic hydroxyl-terminated polymers with phenolic hydroxyl groups at both ends. it can.

(Manufacture of block copolymer)
A unit precursor having a high sulfonic acid group introduction rate and a unit precursor having a low sulfonic acid group introduction rate can be synthesized by a polycondensation reaction, and the polymerization conditions and the like can be performed under the same conditions as described above. One of the unit precursors is terminated with a phenolic hydroxyl group and the other unit precursor is terminated with a halogen, and a block copolymer can be obtained by a polycondensation reaction. Any of the unit precursors may be terminated with a phenolic hydroxyl group, and these unit precursors may be linked using a linking agent to obtain a block copolymer. As the linking group, a divalent or trivalent linking group, or a polyvalent linking group such as decafluorobiphenyl can be used. Any of the unit precursors may be halogen-terminated, and a diol may be used to link these unit precursors to obtain a block copolymer. As the diol, the above-mentioned diols can be similarly applied.

In order to simplify the synthesis process, one of the unit precursors may be synthesized in advance, a monomer may be added to the reaction vessel, the other unit may be synthesized, and a block copolymer may be synthesized.

(Introduction of sulfonic acid group)
The introduction of the sulfonic acid group may be before the synthesis of the block copolymer or after the synthesis of the block copolymer.

Examples of the sulfonating agent include sulfuric acid, chlorosulfonic acid, fuming sulfuric acid and the like. Among these, sulfuric acid and chlorosulfonic acid are preferable because they have appropriate reactivity.

The solvent is not particularly limited as long as it does not inhibit the reaction, and cyclic ethers (dioxane, tetrahydrofuran, etc.), chain ethers (diethyl ether, ethylene glycol dialkyl ether, etc.), nonpolar solvents (toluene, xylene, etc.) Listed are chlorinated solvents (methylene chloride, 1,2-dichloroethane, ethylene chloride, etc.), sulfonic acids (methanesulfonic acid, trifluoromethanesulfonic acid, etc.), sulfuric acid, and water. Of these, chlorinated solvents such as methylene chloride and 1,2-dichloroethane are preferred from the viewpoint of solubility. These may be used alone or in combination of two or more.

What is necessary is just to set reaction temperature suitably according to reaction, Specifically, it is preferable to set to -80 degreeC-200 degreeC which is the optimal use range of a sulfonating agent, -50 degreeC-160 degreeC is more preferable,- 20 to 140 ° C. is more preferable. If the temperature is lower than this range, the reaction tends to be slow, and if the temperature is high, a rapid reaction occurs and sulfonation may progress to other than the intended site.

<Polymer electrolyte membrane>
The polymer electrolyte of the present invention can be used alone or in the form of a complex containing other components and formed into a membrane to be used as a polymer electrolyte membrane.

As a film forming method, a known method can be appropriately used. For example, a film forming method from a solution such as a hot extrusion method, an inflation method, a melt extrusion molding method such as a T-die method, a casting method, or an emulsion method can be exemplified. For example, a method in which a polymer electrolyte is put into an extruder in which a T die is set, and film formation is performed while melt kneading can be mentioned. It is also possible to perform the composite in the film forming process. In the case of the casting method, a polymer electrolyte or polymer electrolyte complex solution with adjusted viscosity is applied onto a flat plate such as a glass plate using a bar coater, blade coater, etc., and the solvent is evaporated to form a membrane. Obtainable. Industrially, it is also common to apply a solution continuously from a coating die onto a belt and vaporize the solvent to obtain a long product.

In order to control the molecular orientation of the polymer electrolyte membrane, the obtained polymer electrolyte membrane may be subjected to a treatment such as biaxial stretching or a heat treatment for controlling the crystallinity. . In order to improve the mechanical strength of the polymer electrolyte membrane, various fillers may be added, or a reinforcing agent such as a glass nonwoven fabric and the polymer electrolyte membrane may be combined by pressing.

As the thickness of the polymer electrolyte membrane, any thickness can be selected according to the application. For example, in consideration of reducing the internal resistance of the obtained polymer electrolyte membrane, the polymer film is preferably as thin as possible. On the other hand, when the gas, methanol barrier property and handling property of the obtained polymer electrolyte membrane are taken into consideration, it may not be preferable if the thickness of the polymer electrolyte membrane is too thin. Considering these, the thickness of the polymer electrolyte membrane is preferably 1.2 μm or more and 350 μm or less. When the thickness of the polymer electrolyte membrane is within the above range, handling is improved, such as easy handling and less damage. The proton conductivity of the polymer electrolyte membrane can also be expressed within a desired range.

It is also possible to introduce a sulfonic acid group after forming a polymer electrolyte membrane. In that case, the method for forming the polymer electrolyte membrane can be read as the method for forming the polymer electrolyte membrane precursor film. That is, a method for producing a film from a polymer that introduces a sulfonic acid group or a complex that includes a polymer that introduces a sulfonic acid group is exemplified. In this case, the polymer electrolyte membrane is finally obtained by sulfonating the film.

In order to further improve the properties of the polymer electrolyte membrane of the present invention, it is possible to irradiate radiation such as electron beam, γ-ray, ion beam and the like. As a result, a crosslinked structure or the like can be introduced into the polymer electrolyte membrane, and the performance may be further improved. Also, various surface treatments such as plasma treatment and corona treatment can improve the properties such as improving the adhesion with the catalyst layer on the surface of the polymer electrolyte membrane.

<Membrane / electrode assembly, fuel cell>
The polymer electrolyte according to the present invention can be used in various industries. The use (use) is not particularly limited, and examples thereof include a membrane / electrode assembly (hereinafter referred to as MEA) in addition to the polymer electrolyte membrane. The MEA can be used for fuel cells such as fuel cells, in particular, polymer electrolyte fuel cells and direct methanol fuel cells.

The polymer electrolyte of the present invention is a hydrocarbon-based material that is inexpensive and has a variety of chemical structures, and has a high ion exchange capacity site that is advantageous for proton conductivity, particularly proton conductivity in a state of low moisture. Therefore, since the membrane / electrode assembly and fuel cell of the present invention include the polymer electrolyte membrane using the polymer electrolyte of the present invention and the catalyst layer binder, high power generation characteristics can be achieved.

An embodiment of a polymer electrolyte fuel cell using the polymer electrolyte membrane of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram schematically showing a cross-sectional structure of a main part of a polymer electrolyte fuel cell using a polymer electrolyte membrane according to the present embodiment. As shown in the figure, a polymer electrolyte fuel cell 10 according to the present embodiment includes a polymer electrolyte membrane 1, catalyst layers 2 and 2, diffusion layers 3 and 3, and separators 4 and 4.

The polymer electrolyte membrane 1 is located substantially at the center of the cell of the solid polymer fuel cell 10. The catalyst layer 2 is provided in contact with the polymer electrolyte membrane 1. The diffusion layer 3 is provided adjacent to the catalyst layer 2, and a separator 4 is disposed on the outer side thereof. The separator 4 is formed with a flow path 5 for feeding fuel gas or liquid (such as aqueous methanol solution) and an oxidant. In other words, these members are configured as cells of the polymer electrolyte fuel cell 10.

Generally, a polymer electrolyte membrane 1 with a catalyst layer 2 joined, or a polymer electrolyte membrane 1 with a catalyst layer 2 and a diffusion layer 3 joined together is a membrane / electrode assembly (also referred to as MEA in this specification). It is used as a basic member of a polymer electrolyte fuel cell.

Methods for producing MEA are conventionally studied polymer electrolyte membranes made of perfluorocarbon sulfonic acid and other hydrocarbon polymer electrolyte membranes (for example, sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfone). A known method performed with a sulfonated polysulfone, a sulfonated polyimide, a sulfonated polyphenylene sulfide, or the like is applicable.

An example of a specific method for producing MEA is shown below, but the present invention is not limited to this.

The catalyst layer 2 is formed by preparing a dispersion solution for forming a catalyst layer by dispersing a metal-supported catalyst in a solution or dispersion of a catalyst layer binder which is a polymer electrolyte. The dispersion solution is applied onto a release film such as PTFE by spraying, and the solvent in the dispersion solution is dried and removed to form a predetermined catalyst layer 2 on the release film. The catalyst layer 2 formed on the release film is disposed on both surfaces of the polymer electrolyte membrane 1, and hot-pressed under predetermined heating and pressurizing conditions to join the polymer electrolyte membrane 1 and the catalyst layer 2 and release them. The MEA in which the catalyst layers 2 are formed on both surfaces of the polymer electrolyte membrane 1 can be produced by peeling the mold film.

Also, a catalyst-carrying gas diffusion electrode in which the dispersion solution is coated on the diffusion layer 3 using a coater or the like, the solvent in the dispersion solution is dried and removed, and the catalyst layer 2 is formed on the diffusion layer 3 Are arranged on both sides of the polymer electrolyte membrane 1, and the catalyst layer 2 side of the catalyst-carrying gas diffusion electrode is placed on both sides of the polymer electrolyte membrane 1 by hot pressing under predetermined heating and pressurizing conditions. An MEA in which the catalyst layer 2 and the diffusion layer 3 are formed can be manufactured. Note that a commercially available gas diffusion electrode (manufactured by E-TEK, Inc., USA) may be used as the catalyst-carrying gas diffusion electrode.

Examples of the polymer electrolyte solution include an alcohol solution of a perfluorocarbon sulfonic acid polymer compound (such as Nafion (registered trademark) solution manufactured by Aldrich) or a sulfonated aromatic polymer compound (eg, sulfonated polyether ether). An organic solvent solution of ketone, sulfonated polyethersulfone, sulfonated polysulfone, sulfonated polyimide, sulfonated polyphenylene sulfide, etc.) can be used. As the metal-supported catalyst, conductive particles having a high specific surface area can be used as a carrier, and examples thereof include carbon materials such as activated carbon, carbon black, ketjen black, vulcan, carbon nanohorn, fullerene, and carbon nanotube.

Any metal catalyst may be used as long as it promotes the fuel oxidation reaction and oxygen reduction reaction, and the fuel electrode and the oxidant electrode may be the same or different. For example, noble metals such as platinum and ruthenium or alloys thereof can be exemplified, and a promoter for promoting their catalytic activity or suppressing poisoning by reaction by-products may be added.

The dispersion solution for forming the catalyst layer may be appropriately diluted with water or an organic solvent in order to adjust the viscosity so that it can be easily applied by spraying or coated by a coater. Moreover, you may mix fluorine-type compounds, such as tetrafluoroethylene, in order to provide water repellency to the catalyst layer 2 as needed.

As the diffusion layer 3, a porous conductive material such as carbon cloth or carbon paper can be used. In order to promote the diffusibility of the fuel and the oxidant and the discharge of reaction by-products and unreacted substances, it is preferable to use those which are coated with tetrafluoroethylene or the like to impart water repellency. Further, an adhesive layer made of a polymer electrolyte as described above may be provided between the polymer electrolyte membrane 1 and the catalyst layer 2 as necessary.

The conditions for hot pressing the polymer electrolyte membrane 1 and the catalyst layer 2 under heating and pressurizing conditions need to be appropriately set according to the type of polymer electrolyte contained in the polymer electrolyte membrane 1 and the catalyst layer 2 to be used. is there. The above-mentioned condition is that the polymer electrolyte contained in the polymer electrolyte membrane 1 or the catalyst layer 2 is generally below the thermal degradation or thermal decomposition temperature of the polymer electrolyte contained in the polymer electrolyte membrane 1 or the catalyst layer 2. It is preferable that the glass transition point and the softening point are higher than the glass transition point, and the temperature condition is higher than the glass transition point and the softening point of the polymer electrolyte contained in the polymer electrolyte membrane 1 and the catalyst layer 2.

As the pressurizing condition, it is preferable that the pressure is in the range of about 0.1 MPa or more and 20 MPa or less because the polymer electrolyte membrane 1 and the catalyst layer 2 are in sufficient contact with each other and there is no deterioration in characteristics due to significant deformation of the material used. In particular, when the MEA is formed only from the polymer electrolyte membrane 1 and the catalyst layer 2, the diffusion layer 3 may be disposed outside the catalyst layer 2 and used only by contacting without being joined.

The MEA obtained by the above method is inserted between a pair of separators 4 in which a flow path 5 for feeding fuel gas or liquid and an oxidant is formed, and the solid according to the present embodiment. A polymer fuel cell 10 is obtained.

As the separator 4, a conductive material such as carbon graphite or stainless steel can be used. In particular, when a metal material such as stainless steel is used, it is preferable to perform a corrosion resistance treatment.

For the polymer electrolyte fuel cell 10 described above, a gas containing hydrogen as a main component or a gas or liquid containing methanol as a main component as a fuel gas or liquid, and a gas containing oxygen (oxygen or oxygen) as an oxidant. The solid polymer fuel cell generates electric power by supplying air) to the catalyst layer 2 via the diffusion layer 3 from the respective separate flow paths 5. At this time, for example, when a hydrogen-containing liquid is used as the fuel, a direct liquid fuel cell is obtained, and when methanol is used, a direct methanol fuel cell is obtained. That is, it can be said that the above-described embodiment exemplified for the polymer electrolyte fuel cell 10 can be applied to a direct liquid fuel cell and a direct methanol fuel cell as they are.

In addition, the polymer electrolyte fuel cell 10 according to the present embodiment can be used alone or in a stacked manner to form a stack, or a fuel cell system incorporating them.

In addition to the examples described above, the polymer electrolyte membrane according to the present invention is disclosed in JP 2001-313046, JP 2001-313047, JP 2001-93551, and JP 2001-93558. JP-A-2001-93561, JP-A-2001-102069, JP-A-2001-102070, JP-A-2001-283888, JP-A-2000-268835, JP-A-2000-268836, It can be used as an electrolyte membrane of a polymer electrolyte fuel cell or a direct methanol fuel cell, which is publicly known in Japanese Laid-Open Patent Publication No. 2001-283893. Based on these known patent documents, those skilled in the art can easily construct a solid polymer fuel cell or a direct methanol fuel cell using the polymer electrolyte membrane of the present invention.

Hereinafter, examples will be shown, and the embodiment of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples.

The molecular weight of the polymer obtained in the synthesis example, the ion exchange capacity of the polymer electrolyte obtained in the example, and the proton conductivity of the polymer electrolyte membrane were measured as follows.

[Measurement method of molecular weight]
The molecular weight was measured by GPC method. The conditions are as follows.

GPC measuring device HLC-8220 manufactured by TOSOH
Two columns, Super AW 4000 and Super AW 2500, manufactured by SHOWA DENKO, are connected in series. Column temperature 40 ° C
Mobile phase solvent NMP (LiBr added to 10 mmol / dm ³ )
Solvent flow rate 0.3 mL / min
[Method of measuring ion exchange capacity (hereinafter abbreviated as IEC)]
A target electrolyte membrane (about 100 mg: sufficiently dried) was immersed in 20 mL of a saturated aqueous solution of sodium chloride at 25 ° C., and subjected to an ion exchange reaction in a water bath at 60 ° C. for 3 hours. After cooling to 25 ° C., the membrane was thoroughly washed with ion exchanged water, and all of the saturated aqueous sodium chloride solution and the washing water were collected. To this collected solution, a phenolphthalein solution was added as an indicator, and neutralization titration was performed with a 0.01N sodium hydroxide aqueous solution to calculate IEC.

[Measurement method of proton conductivity]
Proton conductivity measurement is performed using a constant temperature and humidity chamber (manufactured by ESPEC, SH-221), keeping the temperature and humidity constant (about 3 hours), and using an impedance analyzer (manufactured by Hioki, 3532-50) The resistance of was measured. Specifically, the frequency response from 50 kHz to 5 MHz was measured with an impedance analyzer, and the proton conductivity was calculated from the following equation.
Proton conductivity (S / cm) = D / (W × T × R)
Here, D is a distance between electrodes (cm), W is a film width (cm), T is a film thickness (cm), and R is a measured resistance value (Ω). In this measurement, D = 1 cm and W = 1 cm, and the film thickness was a value measured using a micrometer for each sample. The temperature and humidity were 85 ° C. and 30% RH, respectively.

[Synthesis Example 1]
12.4 g of 4,4′-difluorodiphenylsulfone, 10.2 g of 4,4′-dihydroxybenzophenone, 8.6 g of potassium carbonate, 50 ml of DMAc and 15 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 8 hours, the reaction solution was added to water after cooling to room temperature, and the precipitated polymer was finely pulverized with a mixer, filtered and dried to obtain a polymer (hereinafter referred to as P1). The molecular weight of the obtained P1 was Mn = 44000.

Further, this P1 was dissolved in 100 g of 2 g dichloromethane, and sulfonation was carried out by adding 10 ml of chlorosulfonic acid. The IEC was 0.05 meq / g. The sulfonic acid group introduction rate was 0.01%.

[Synthesis Example 2]
In Synthesis Example 1, 3.0 g of 2,6-difluorobenzonitrile and 4.2 g of 2,2′-dihydroxybiphenyl were used in place of 4,4′-difluorodiphenylsulfone and 4,4′-dihydroxybenzophenone. Were synthesized in the same manner to obtain a white polymer (hereinafter referred to as P2). The molecular weight of the obtained P2 was Mn = 10000. When P2 was sulfonated in the same manner as P1, IEC was 3.62 meq / g. The introduction rate of sulfonic acid group was 52%.

[Synthesis Example 3]
In Synthesis Example 1, instead of 4,4′-difluorodiphenyl sulfone and 4,4′-dihydroxybenzophenone, 3.0 g of 2,6-difluorobenzonitrile and 4.2 g of 4,4′-dihydroxybiphenyl and 2,2 A white polymer (hereinafter referred to as P3) was obtained in the same manner except that 4.2 g of '-dihydroxybiphenyl was used. The molecular weight of the obtained P3 was Mn = 11000. Further, when this P3 was sulfonated in the same manner as P1, the IEC was 3.48 meq / g. The introduction rate of sulfonic acid group was 46%.

[Synthesis Example 4]
In Synthesis Example 1, 2.6 g of 2,6-difluorobenzonitrile and 4,4 ′-(9-fluorenylidene) diphenol in place of 4,4′-difluorodiphenylsulfone and 4,4′-dihydroxybenzophenone A white polymer (hereinafter referred to as P4) was obtained in the same manner except that 0 g was used. The molecular weight of the obtained P4 was Mn = 8000. Further, when this P4 was sulfonated in the same manner as P1, the IEC was 4.03 meq / g. The introduction rate of sulfonic acid group was 53%.

[Synthesis Example 5]
In Synthesis Example 1, instead of 4,4′-difluorodiphenylsulfone and 4,4′-dihydroxybenzophenone, 7.1 g of 2,6-difluorobenzonitrile and 13.9 g of 1,1′-bi-2-naphthol were used. A white polymer (hereinafter referred to as P5) was obtained in the same manner except that it was used. The molecular weight of the obtained P5 was Mn = 13000. Further, when this P5 was sulfonated in the same manner as P1, the IEC was 2.88 meq / g. The sulfonic acid group introduction rate was 48%.

[Synthesis Example 6]
Synthesis was performed in the same manner as in Synthesis Example 1 except that 4.5 g of hydroquinone was used instead of 4,4′-dihydroxybenzophenone, and a white polymer was obtained (hereinafter referred to as P6). The molecular weight of P6 was Mn = 4400. Further, when this P6 was sulfonated in the same manner as P1, the IEC was 2.05 meq / g. The introduction rate of sulfonic acid group was 26%.

[Synthesis Example 7]
3.0 g of 2,6-difluorobenzonitrile and 4.2 g of 2-phenylhydroquinone, 4.5 g of potassium carbonate, 10 ml of DMAc and 5 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After cooling to room temperature after 8 hours, the reaction solution was added to water, and the precipitated polymer was finely pulverized with a mixer, filtered and dried to obtain a polymer (hereinafter referred to as P7). The molecular weight of the obtained P7 was Mn = 14000. Further, when this P7 was sulfonated in the same manner as P1, the IEC was 3.58 meq / g. The sulfonic acid group introduction rate was 48%.

[Synthesis Example 8]
3.0 g of 2,6-difluorobenzonitrile and 2.1 g of 4,4′-dihydroxybiphenyl and 2.1 g of 2,2′-dihydroxybiphenyl, 4.5 g of potassium carbonate, 10 ml of DMAc and 5 ml of toluene were mixed under a nitrogen atmosphere. Heated to 180 degrees. After 8 hours, the reaction solution was added to water after cooling to room temperature, and the precipitated polymer was finely pulverized with a mixer, filtered and dried to obtain a polymer (hereinafter referred to as P8). The molecular weight of the obtained P8 was Mn = 11000. Further, when this P8 was sulfonated in the same manner as P1, the IEC was 3.52 meq / g. The introduction rate of sulfonic acid group was 47%.

[Example 1]
1.14 g of 4,4′-difluorodiphenylsulfone, 1.00 g of 4,4′-dihydroxybenzophenone, 0.9 g of potassium carbonate, 5 ml of DMAc, and 2 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 1.5 hours, the mixture was cooled, 1.5 g of P2 was added, and the mixture was further reacted at 135 degrees for 7 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The block polymer was obtained by pulverization with a mixer, filtration, and washing with methanol, followed by drying at 80 ° C. under reduced pressure. The molecular weight of the obtained block polymer was Mn 58000. 3 g of the obtained block polymer was dissolved in 100 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.70 meq / g. The proton conductivity measured under low humidification conditions was 3.2 × 10 ⁻⁴ S / cm.

[Example 2]
3.04 g of 4,4′-difluorodiphenylsulfone, 2.66 g of 4,4′-dihydroxybenzophenone, 2.2 g of potassium carbonate, 10 ml of DMAc and 4 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 1.5 hours, the mixture was cooled, 3.98 g of P3 was added, and further reacted at 135 degrees for 5 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The block polymer was obtained by pulverization with a mixer, filtration, and washing with methanol, followed by drying at 80 ° C. under reduced pressure. The molecular weight of the obtained block polymer was Mn79000. 3 g of the obtained block polymer was dissolved in 60 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.63 meq / g. The proton conductivity measured under low humidification conditions was 3.5 × 10 ⁻⁴ S / cm.

Example 3
2.24 g of 4,4′-difluorodiphenylsulfone, 1.96 g of 4,4′-dihydroxybenzophenone, 1.6 g of potassium carbonate, 5 ml of DMAc, and 2 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 2 hours, the mixture was cooled, 1.85 g of P4 was added, and further reacted at 135 degrees for 3 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The block polymer was obtained by pulverization with a mixer, filtration, and washing with methanol, followed by drying at 80 ° C. under reduced pressure. The molecular weight of the obtained block polymer was Mn56000. 5 g of the obtained block polymer was dissolved in 200 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.55 meq / g. When proton conductivity was measured under low humidification conditions, it was 3.0 × 10 ⁻³ S / cm.

Example 4
1.68 g of 4,4′-difluorodiphenylsulfone, 1.47 g of 4,4′-dihydroxybenzophenone, 1.2 g of potassium carbonate, 5 ml of DMAc, and 2 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 2 hours, the mixture was cooled, 3.00 g of P5 was added, and further reacted at 135 degrees for 3 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The block polymer was obtained by pulverization with a mixer, filtration, and washing with methanol, followed by drying at 80 ° C. under reduced pressure. The molecular weight of the obtained block polymer was Mn39000. 3 g of the obtained block polymer was dissolved in 60 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.81 meq / g. The proton conductivity measured under low humidification conditions was 3.7 × 10 ⁻⁴ S / cm.

Example 5
1.23 g of 4,4′-difluorodiphenylsulfone, 1.00 g of 4,4′-dihydroxybenzophenone, 1.0 g of potassium carbonate, 10 ml of DMAc, and 4 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 1.5 hours, the mixture was cooled, 1.50 g of P7 was added, and the mixture was further reacted at 150 degrees for 5 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The block polymer was obtained by pulverization with a mixer, filtration, and washing with methanol, followed by drying at 80 ° C. under reduced pressure. The molecular weight of the obtained block polymer was Mn62000. 3 g of the obtained block polymer was dissolved in 60 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.48 meq / g. The proton conductivity measured under low humidification conditions was 2.8 × 10 ⁻⁴ S / cm.

Example 6
1.23 g of 4,4′-difluorodiphenylsulfone, 1.00 g of 4,4′-dihydroxybenzophenone, 1.0 g of potassium carbonate, 10 ml of DMAc, and 4 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 1.5 hours, the mixture was cooled, 1.50 g of P2 was added, and further reacted at 150 degrees for 5 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The block polymer was obtained by pulverization with a mixer, filtration, and washing with methanol, followed by drying at 80 ° C. under reduced pressure. The molecular weight of the obtained block polymer was Mn 70000. 3 g of the obtained block polymer was dissolved in 60 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.70 meq / g. The proton conductivity measured under low humidification conditions was 3.2 × 10 ⁻⁴ S / cm.

Example 7
1.23 g of 4,4′-difluorodiphenylsulfone, 1.00 g of 4,4′-dihydroxybenzophenone, 1.0 g of potassium carbonate, 10 ml of DMAc, and 4 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 1.5 hours, the mixture was cooled, 1.50 g of P8 was added, and further reacted at 150 degrees for 5 hours. After the reaction, the reaction solution was cooled to room temperature, and the reaction solution was added to water to obtain a white solid. The block polymer was obtained by pulverization with a mixer, filtration, and washing with methanol, followed by drying at 80 ° C. under reduced pressure. The molecular weight of the obtained block polymer was Mn72000. 3 g of the obtained block polymer was dissolved in 60 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.63 meq / g. The proton conductivity measured under low humidification conditions was 3.5 × 10 ⁻⁴ S / cm.

[Comparative Example 1]
In Synthesis Example 1, 10 g of a polymer (Mn = 47200) synthesized in the same manner except that 4.5 g of 4,4′-dihydroxydiphenyl sulfone was used instead of 4,4′-dihydroxybenzophenone in 30% fuming sulfuric acid. In addition, sulfonation was performed at 100 ° C. for 20 hours to obtain a polymer electrolyte. The obtained polymer electrolyte was added to a large amount of water, and filtered and washed with water. The obtained polymer electrolyte was easily soluble in water, and only 1.2 g was obtained.

After dissolving 1 g of the washed polymer electrolyte in DMSO, the solution was cast on a glass plate, vacuum-dried at 60 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours. When it was peeled off, it melted when water was applied.

[Comparative Example 2]
In Synthesis Example 2, 6 g of a polymer (Mn = 47200) synthesized in the same manner as in Example 1 except that 4.5 g of 4,4′-dihydroxydiphenyl ether was used instead of 2,2′-dihydroxybiphenyl. Sulfonation gave a polymer electrolyte. After sulfonation, in addition to a large amount of water, filtration and washing with water were performed. The polymer electrolyte swelled severely by sucking water, but 5 g could be obtained.

After 0.5 g of the obtained polymer electrolyte was dissolved in DMSO, the solution was cast on a glass plate, vacuum-dried at 60 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours. When it was peeled from the board, it melted when water was applied.

[Comparative Example 3]
In Example 1, a polymer electrolyte was obtained in the same manner except that 1 g of P6 was used instead of P2.

After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast on a glass plate, vacuum-dried at 60 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours. It was easily peeled off when swollen and swollen. Again, it was vacuum-dried at 120 ° C. for 12 hours to obtain a self-supporting polymer electrolyte membrane.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.63 meq / g. Under low humidification conditions, the membrane resistivity was high and proton conductivity could not be measured.

[Comparative Example 4]
3.72 g of 4,4′-difluorodiphenylsulfone, 3.78 g of 4,4′-dihydroxydiphenylsulfone, 1.29 g of 2,6-difluorobenzonitrile and 1.73 g of 4,4′-dihydroxybiphenyl, potassium carbonate 4. 3 g, 24 ml of DMAc and 7 ml of toluene were mixed in a nitrogen atmosphere and heated to 180 degrees. After 8 hours, the reaction solution was added to water after cooling to room temperature, and the precipitated polymer was finely pulverized with a mixer, filtered and dried to obtain a polymer. The molecular weight of the polymer of the obtained random copolymer was Mn = 48000. 3 g of the obtained polymer was dissolved in 60 ml of dichloromethane, and 10 ml of chlorosulfonic acid was added to carry out sulfonation. The supernatant solution was removed, the precipitate was added to a large amount of water, washed with a large amount of water until pH reached 7 while being crushed with a mixer and filtered. The obtained solid was dried to obtain a polymer electrolyte.

After dissolving 1 g of the obtained polymer electrolyte in DMSO, the solution was cast-coated on a glass substrate, vacuum-dried at 80 ° C. for 15 hours, and further vacuum-dried at 120 ° C. for 18 hours to be self-supporting. As a result, a polymer electrolyte membrane was obtained.

The obtained polymer electrolyte membrane had an ion exchange capacity of 1.47 meq / g. The proton conductivity measured under low humidification conditions was 6.6 × 10 ⁻⁵ S / cm.

From comparison between Examples 1 to 4 and Comparative Examples 1 and 2, it can be seen that the block copolymer (polymer electrolyte) of the present invention has good water resistance.

From comparison between Examples 1 to 7 and Comparative Examples 3 and 4, it can be seen that the block copolymer (polymer electrolyte) of the present invention exhibits excellent proton conductivity under low humidification conditions.

It is clear that the polymer electrolyte of the present invention is useful as a material for a solid polymer fuel cell, and particularly useful as a polymer electrolyte membrane.

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2 Catalyst layer 3 Diffusion layer 4 Separator 5 Flow path 10 Polymer electrolyte fuel cell

Claims (10)

A block copolymer including a unit having a high sulfonic acid group introduction rate and a unit having a low sulfonic acid group introduction rate, and the unit having a high sulfonic acid group introduction rate is represented by the following formula (1):

(In formula (1), X ¹ represents O, S, NH or a direct bond.)
And / or the following formula (2):

(In formula (2), X ¹ is the same as above.)
A polyelectrolyte comprising the structure represented by The unit having a high sulfonic acid group introduction rate is represented by the following formula (3):

(In formula (3), X ¹ is the same as above. X ² represents O, S, NH, CO, SO ₂ , C (CF ₃ ) ₂ , isopropylidene, fluorenylidene or a direct bond, R ¹ represents fluorine, chlorine, bromine, alkyl groups having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, indicates a heteroaromatic ring or an alkoxy group having 1 to 10 carbon atoms, containing nitrogen at 1 to 9 carbon atoms, ^{R 1} is When there are a plurality, they may be the same or different, a, b, c and d each represent 0 or 1, e represents any one of 0 to 4, and f represents any one from 0 to 6. X ¹ , X ² , R ¹ , e, and f may be the same or different when there are a plurality of them, and Y represents the following formula (4):

Or the following formula (5):

Indicates. 2. The polymer electrolyte according to claim 1, comprising a structure in which a sulfonic acid group is introduced into the structure represented by A unit having a high sulfonic acid group introduction rate is a structure in which a and d are 1, b and c are 0, and X ¹ is O in the above formula (3), and / or a and d in the above formula (3). 3. The polymer electrolyte according to claim 2, comprising a structure in which a sulfonic acid group is introduced into a structure in which n is 0, b and c are 1, and X ¹ is O. 4. The polymer electrolyte according to any one of claims 1 to 3, wherein 45 to 80% of aromatic rings contained in a unit having a high introduction rate of sulfonic acid groups have a sulfonic acid group. A unit having a low sulfonic acid group introduction rate is represented by the following formula (8):

(In the formula (8), X ³ represents CO or SO _2. Z ¹ represents hydrogen, a metal ion, or an ammonium ion. I represents 0 to 2, and R ³ may be substituted with fluorine. A good alkyl group having 1 to 10 carbon atoms, CN, COZ ² , or SO ₂ Z ² , wherein Z ² is an optionally substituted alkyl group having 1 to 10 carbon atoms or aryl having 6 to 12 carbon atoms In some cases, they may be the same or different, e represents a value of 0 to 4, and j represents a value of 0 to 1. However, when i = 1, the sum of j Is a value less than 2.)
The polymer electrolyte in any one of Claims 1-4 containing the structure shown by these. 6. The polymer electrolyte according to claim 5, wherein the unit having a low introduction rate of sulfonic acid group includes a structure in which e is 0, i is 1, and j is 0 in the above formula (8). The polymer electrolyte membrane containing the polymer electrolyte as described in any one of Claims 1-6. A membrane electrode assembly comprising the polymer electrolyte membrane according to claim 7. A solid polymer fuel cell comprising the polymer electrolyte membrane according to claim 7. A polymer electrolyte fuel cell comprising the membrane electrode assembly according to claim 8.

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