JP6547223B2 - Polymer electrolyte membrane, membrane / electrode assembly and fuel cell - Google Patents

Description

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

In recent years, from the viewpoint of environmental problems such as global warming, development of a highly efficient and clean energy source is required. Fuel cells are attracting attention as one candidate for the demand. A fuel cell supplies fuel such as hydrogen gas and methanol and an oxidant such as oxygen to electrodes respectively separated by an electrolyte, oxidizes the fuel on the one hand, reduces the oxidant on the other hand, and generates electricity directly. is there. Among the above-described fuel cell materials, one of the most important materials is the electrolyte. Various types of electrolyte membranes have been developed as electrolyte membranes for separating the fuel composed of the electrolyte and the oxidant, but in recent years, in particular, they are composed of a polymer compound containing a proton conducting functional group such as a sulfonic acid group. Development of polymer electrolytes. Such a polymer electrolyte is also used as a raw material of an electrochemical element such as a humidity sensor, a gas sensor, an electrochromic display element, etc. besides a polymer electrolyte fuel cell. Among the uses of these polymer electrolytes, in particular, polymer electrolyte fuel cells are expected as one of the pillars of new energy technology. For example, a solid polymer fuel cell using an electrolyte membrane composed of a polymer compound having a proton conductive functional group has all the features that can operate at low temperature, can be reduced in size and weight, and can be used as a mobile vehicle such as an automobile Applications to cogeneration systems for automobiles and small portable devices for consumer use are being considered.

As an electrolyte membrane used for a polymer electrolyte fuel cell, there is a styrenic cation exchange membrane developed in the 1950s, but a fuel cell having poor stability in a fuel cell operating environment and a sufficient life span It has not come to manufacture. On the other hand, perfluorocarbon sulfonic acid membranes represented by Nafion (registered trademark) are widely studied as electrolyte membranes having practical stability. Perfluorocarbon sulfonic acid membranes have high proton conductivity and are considered to be excellent in chemical stability such as acid resistance and oxidation resistance. However, Nafion (registered trademark) has the disadvantage that it is very expensive because the raw materials used are high and the production process is complicated. In addition, it is pointed out that hydrogen peroxide generated by the electrode reaction and its degradation product by hydroxy radical are deteriorated. Furthermore, due to its structure, there is a limit to the introduction of a sulfonic acid group that is a proton conducting group.

From such a background, development of a hydrocarbon-based electrolyte membrane has come to be expected again. The reason is that hydrocarbon-based electrolyte membranes can easily have a variety of chemical structures, and the range of introduction of proton conducting groups such as sulfonic acid groups can be widely adjusted, complexation with other materials, introduction of crosslinking, etc. Is relatively easy.

In recent years, there has been an example of improving proton conductivity by introducing a large number of sulfonic acid groups into the electrolyte membrane, but such a membrane swells significantly in a water-containing state, and the membrane is The strength is lost, and there is a problem in using it as an electrolyte membrane for a fuel cell.

Therefore, it has been proposed to reinforce the electrolyte membrane with a porous substrate. Patent Document 1 shows a method of combining various polymer electrolytes such as fluorine type and hydrocarbon type with inorganic fibers such as glass cloth by thermocompression bonding. However, in the polymer electrolyte exemplified here, although the strength can be improved by complexing, the problem is the decrease in proton conductivity at low humidification. Patent Document 2 discloses a polymer electrolyte membrane having a reinforcing material such as glass fiber. However, the polymer electrolyte exemplified here is an alkaline polymer or an acidic polymer, and the problem is also the reduction in proton conductivity at low humidity due to the composite.

JP, 2006-128014, A Japanese Patent Application Publication No. 2009-545841

It is an object of the present invention to provide a hydrocarbon-based polymer reinforced by a glass non-woven fabric which exhibits high proton conductivity and high swelling resistance, and thus is high in wet-wet cycle resistance and suitable for use as an electrolyte membrane for fuel cells. It is providing a molecular electrolyte membrane.

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that a composite film formed by forming a specific glass non-woven fabric together with an electrolyte resin is superior in swelling resistance compared to a film of an electrolyte resin alone, It has been found that even in tests for evaluating mechanical stability such as cycle tests, higher durability is exhibited, and the present invention has been completed.

That is, according to the present invention, a unit substantially derived from a hydrophobic portion oligomer having a main chain mainly composed of an aromatic ring group, and a sulfonic acid group, the main chain mainly comprising an aromatic group, having substantially no sulfonic acid group A polymer electrolyte membrane comprising a polymer electrolyte having as a main chain a unit derived from a hydrophilic moiety oligomer comprising a ring group and a glass nonwoven fabric, wherein the glass nonwoven fabric has a mean diameter of 1 μm or less The present invention relates to a polymer electrolyte membrane including fibers and treated with a silicon compound binder or an epoxy compound binder.

The glass nonwoven fabric preferably further comprises glass fibers having an average diameter of more than 1 μm and less than 10 μm.

It is preferable that the glass non-woven fabric is treated with an epoxy compound binder.

（式中、Ａｒ^１は、下記式群（２）に記載の構造のいずれかを有する２価の基を表し、当該２価の基は置換基を有していてもよい。Ａｒ^２は、スルホン酸基を少なくとも１つ有する２価の芳香族基を表す。Ａｒ^１またはＡｒ^２が複数存在する場合は、それらは同一であっても異なっていてもよい。ｎは１〜４の整数、Ｘは−Ｏ−または−Ｓ−、Ｙは−ＳＯ_２−または−ＣＯ−を表す。）

It is preferable that the unit derived from the hydrophilic part oligomer contains at least one of the structures described in the following general formula group (1) as a repeating unit.

(Wherein, Ar ¹ represents a divalent group having any of the structures described in the following formula group (2), and the divalent group may have a substituent. Ar ² is And represents a divalent aromatic group having at least one sulfonic acid group, and when a plurality of Ar ¹ or Ar ² are present, they may be the same or different, n is an integer of 1 to 4, X represents -O- or -S-, and Y represents -SO ₂ -or -CO-).

It is preferable that Ar ² is a divalent aromatic group having any of the structures described in the following formula group (3) and having at least one sulfonic acid group.

（式中、Ａｒは、２価の芳香族基を表す。Ａｒが複数存在する場合は、それらは同一であっても異なっていてもよい。） It is preferable that the unit derived from the hydrophobic moiety oligomer contains at least one of the structures described in the following general formula group (4) as a repeating unit.

(Wherein, Ar represents a divalent aromatic group. When there are a plurality of Ar, they may be the same or different).

The ion exchange capacity of the polymer electrolyte membrane is 1.5 to 3.5 meq. It is preferable that it is / g.

The present invention also relates to a membrane / electrode assembly for a fuel cell, using the polymer electrolyte membrane of the present invention.

The present invention also relates to a fuel cell using the polymer electrolyte membrane of the present invention.

According to the present invention, by combining a specific glass nonwoven fabric with a polymer electrolyte having a specific structure, the dimensional change at the time of water absorption is suppressed, the mechanical strength is excellent, and the high proton conductivity even under low humidity It is possible to provide a polymer electrolyte membrane having conductivity. Further, by using this polymer electrolyte membrane, high performance and high mechanical strength can be realized regardless of the humidity of the fuel gas, so that a highly reliable fuel cell for long-term use can be provided.

It is a dry-wet cycle tolerance comparative test result of Example 6 and Comparative Example 1.

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

<1. Polymer electrolyte>
The polymer electrolyte used in the present invention, that is, the polymer electrolyte composited with the glass non-woven fabric, is substantially free of sulfonic acid groups, and is a unit derived from a hydrophobic moiety oligomer mainly composed of an aromatic ring group in the main chain, A unit having a sulfonic acid group and having a main chain mainly derived from an aromatic ring group and having a unit derived from a hydrophilic portion oligomer is a main chain. It is preferable that the said polymer electrolyte is a block copolymer which consists of a unit derived from a hydrophobic part oligomer, and a unit derived from a hydrophilic part oligomer. By using a block copolymer, the proton conductivity of the polymer electrolyte under low humidity can be improved.

The unit derived from the hydrophilic part oligomer has a sulfonic acid group, and the main chain is mainly composed of an aromatic ring group. That is, the sulfonic acid group is introduce | transduced into the unit derived from the said hydrophilic part oligomer. Since the unit derived from the hydrophilic moiety oligomer has a sulfonic acid group, the proton conductivity of the polymer electrolyte is expressed, and the main chain of the unit derived from the hydrophilic moiety oligomer mainly comprises an aromatic ring group. It has excellent heat resistance and chemical durability.

The sulfonic acid group may be, for example, a salt such as sodium salt or potassium salt, or may be a sulfonic acid ester group such as neopentyl ester, methyl ester or propyl ester. Particularly during oligomer synthesis or after synthesis, it is often preferable to have a protective group such as a salt or ester, but when the polymer electrolyte is used as, for example, an electrolyte membrane of a fuel cell, it is inorganic It is often used by converting it to a sulfonic acid group by immersion in an aqueous solution of acid or the like. Therefore, in the present invention, as a sulfonic acid group, a state having a protective group such as a salt or an ester is also included as long as it easily becomes a sulfonic acid group.

The amount of the sulfonic acid group is preferably 1 to 6 per repeating unit forming a unit derived from the hydrophilic part oligomer, and more preferably 1 to 4. With more than 6 units, the units become more water soluble and tend to be difficult to handle during synthesis. If the number is less than one, sufficient proton conductivity tends to be difficult to develop.

The unit derived from the hydrophilic moiety oligomer is one whose main chain is mainly composed of an aromatic ring group. Here, "the main chain is mainly composed of an aromatic ring group" means that the molecular weight of the portion other than the main chain linking group (ether group, thioether group, sulfone group, ketone group, sulfide group etc.) in the unit is 100%. When it does, it means that 70% or more consists of an aromatic ring group. Examples of the aromatic ring group include benzene, naphthalene, anthracene, biphenyl and aromatic heterocyclic groups containing sulfur, nitrogen and the like.
When the main chain is mainly composed of an aromatic ring group, the chemical thermal stability is high. Examples of such a main chain structure include polyether, polyether ketone, polyether ether ketone, polyether sulfone, polyether ether sulfone, polyketone, polysulfone, polysulfide, polyphenylene, polyimide, polybenzimidazole and the like.

（式中、Ａｒ^１は、下記式群（２）に記載の構造のいずれかを有する２価の基を表し、当該２価の基は置換基を有していてもよい。Ａｒ^２は、スルホン酸基を少なくとも１つ有する２価の芳香族基を表す。Ａｒ^１またはＡｒ^２が複数存在する場合は、互いに同じであっても異なっていてもよい。ｎは１〜４の整数、Ｘは−Ｏ−または−Ｓ−、Ｙは−ＳＯ_２−または−ＣＯ−を表す。）

Specific examples of the unit derived from the hydrophilic moiety oligomer include those containing at least one of the structures described in the following general formula group (1) as a repeating unit.

(Wherein, Ar ¹ represents a divalent group having any of the structures described in the following formula group (2), and the divalent group may have a substituent. Ar ² is And represents a divalent aromatic group having at least one sulfonic acid group, and when a plurality of Ar ¹ or Ar ² are present, they may be the same or different from each other, n is an integer of 1 to 4, X is -O- or -S-, Y is -SO ₂ - represents a or -CO-).

In addition, Ar ² has one of the structures described in the following formula group (3) and is a divalent aromatic group having at least one sulfonic acid group, that is, the following formula group (3 It is preferable from the easiness of the synthesis that it is a structure in which at least one sulfonic acid group is introduced into a divalent aromatic group having any of the structures described in 1.).

The structure described in the above general formula group (1) may have a substituent on the benzene ring. Moreover, the bivalent group which has a structure as described in said Formula group (2) may have a substituent. Furthermore, the bivalent aromatic group which has a structure as described in said Formula group (3) may have a substituent other than a sulfonic acid group. As these substituents, for example, an alkyl group having 1 to 6 carbon atoms (methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, etc.), an alkoxy group having 1 to 6 carbon atoms (methoxy group, ethoxy group) Group, propoxy group, butoxy group, pentyloxy group, hexyloxy group etc., phenyl group and the like. Moreover, it can have one or more of the said substituent. The unit derived from the hydrophilic part oligomer may have a sulfonic acid group in any of its main chain, side chain, both (main chain and side chain).

As a monomer which comprises a hydrophilic part oligomer, the monomer which can comprise the structure as described in said General formula group (1) is mentioned, for example, Specifically, the monomer represented by the following Formula is mentioned preferably. Moreover, when X is -S- or the like in the general formula group (1), monomers having an -SH group instead of an -OH group may be mentioned as monomers represented by the following formula. Furthermore, as described later, in the case of preparing a hydrophilic portion oligomer by polymerization of a monomer having a sulfonic acid group, etc., in the monomer represented by the following formula, a monomer having a sulfonic acid group on its benzene ring Etc.

In addition, as a monomer which comprises a hydrophilic part oligomer, what is shown by Unexamined-Japanese-Patent No. 2002-293889 etc. (The monomer etc. which have an electron withdrawing group and an electron donor group) can also be illustrated.

The ion exchange capacity of the unit derived only from the hydrophilic part oligomer (hereinafter, the ion exchange capacity is also described as IEC) can be set high in the IEC as a polymer electrolyte membrane, and expresses high proton conductivity under low humidity 4.0 meq. It is preferable that it is / g or more. The IEC of the unit derived from the hydrophilic part oligomer is calculated by NMR analysis, or the IEC of the block electrolyte (which can be easily obtained by a conventionally known method such as titration) by the weight ratio of the unit derived from the hydrophilic part oligomer Although it can obtain | require by dividing | segmenting etc., it calculates | requires by the latter method in this specification. That is, the IEC of the unit derived from the hydrophilic part oligomer is the weight ratio of the unit derived from the hydrophilic part oligomer of the IEC of the polymer electrolyte determined in the same manner as the measuring method of the IEC of the polymer electrolyte membrane described in the examples. Calculated by dividing by. Also, meq. / G means milliequivalents / g.

The units derived from the hydrophobic moiety oligomer are substantially free of sulfonic acid groups. The phrase "substantially free of sulfonic acid groups" means that the unit derived from the hydrophobic moiety oligomer has no sulfonic acid group at all, or the number of sulfonic acid groups per repeating unit in the unit derived from the hydrophobic moiety oligomer It means that it is 1/10 or less of the number of the sulfonic acid groups per repeating unit in the unit derived from a hydrophilic part oligomer. Thereby, the phase separation with the hydrophilic part is clarified, the proton conductivity of the polymer electrolyte under low humidity is improved, and the strength of the polymer electrolyte is improved. Preferably, no sulfonic acid group is introduced into the unit derived from the hydrophobic moiety oligomer.

The unit derived from the hydrophobic moiety oligomer is preferably a polyimide type, polybenzimidazole type, polyether type or the like from the viewpoint of heat resistance, and the main chain is preferably composed mainly of an aromatic ring group, and the polyether type is synthesized From the viewpoint of ease of “The main chain is mainly composed of an aromatic ring group” means that the molecular weight of the portion other than the connecting group (ether group, sulfone group, ketone group, sulfide group etc.) of the main chain in the unit is 100%. % Means that it consists of an aromatic ring group.

（式中、Ａｒは、２価の芳香族基を表す。Ａｒが複数存在する場合は、それらは同一であっても異なっていてもよい。） As a unit derived from such a hydrophobic part oligomer, it is preferable to include at least one of the structures described in the following general formula group (4) as a repeating unit.

(Wherein, Ar represents a divalent aromatic group. When there are a plurality of Ar, they may be the same or different).

As a bivalent aromatic group of Ar, the group etc. which are represented by the following Formula group (5) are mentioned preferably, for example.

In addition, the divalent aromatic group of Ar may have a substituent. As the substituent, for example, an alkyl group having 1 to 6 carbon atoms (a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, etc.), an alkoxy group having 1 to 6 carbon atoms (a methoxy group, an ethoxy group) Groups, propoxy group, butoxy group, pentyloxy group, hexyloxy group etc.), phenyl group, cyano group etc. may be mentioned. Moreover, it can have one or more of the said substituent.

As a monomer which comprises a hydrophobic part oligomer, the monomer which can comprise the structure of the said General formula group (4) is mentioned, for example, Specifically, the monomer represented by the following Formula is mentioned preferably.

The molecular weight of the unit derived from the hydrophilic moiety oligomer and the unit derived from the hydrophobic moiety oligomer varies depending on the chemical structure and easiness of synthesis, etc., but the number average molecular weight is 700 to 30,000 [g / mol], respectively. Is preferable, and 2,000 to 10,000 [g / mol] is more preferable. If it is smaller than 700 [g / mol], the characteristics as a block copolymer type polymer electrolyte tend to be difficult to appear, and if it is larger than 30,000 [g / mol], the synthesis becomes difficult due to problems such as solubility. It tends to be

The molecular weight of the polyelectrolyte is preferably 10,000 to 300,000 [g / mol] in terms of number average molecular weight, and from the balance of easiness of synthesis and solubility in solvent, 30,000 to 150,000 [g / mol] Is more preferred. The molecular weight of each said oligomer and polyelectrolyte can be calculated | required by the measuring method as described in an Example.

Further, the IEC of the polymer electrolyte is 1.5 to 3.5 meq. It is preferable in order that it is easy to express the performance as electrolyte as it is / g, and 1.6-3.0 meq. It is more preferable because it is excellent in the balance of proton conductivity and mechanical strength under low humidification if it is / g. The ion exchange capacity of the said polymer electrolyte can be calculated | required similarly to the measuring method as described in an Example.

Further, it is also within the scope of the present invention to subject the polymer electrolyte to chemical modification such as introduction of crosslinking in order to further improve the mechanical strength and to suppress the swelling to water.

The polymer electrolyte can be produced by a conventionally known method. For example, after preparing an oligomer capable of becoming a hydrophilic part oligomer, this and a hydrophobic part oligomer are block copolymerized, and only a unit capable of becoming a hydrophilic part of the block copolymer is sulfonated to form a hydrophilic part-hydrophobic part block copolymer Method (Method (a)): After preparing an oligomer capable of becoming a hydrophilic part oligomer, a sulfonic acid group is introduced to prepare a hydrophilic part oligomer, and this and a hydrophobic part oligomer are block copolymerized (method (Method (a)) b) Method of preparing a hydrophilic part oligomer by polymerizing a monomer having a sulfonic acid group and block copolymerizing this with a hydrophobic part oligomer (method (c)); Large amount having a hydrophobic part oligomer and a sulfonic acid group By polymerizing the monomer of (1), and consequently the unit derived from the hydrophilic moiety oligomer and the unit derived from the hydrophobic moiety oligomer How to block copolymer consisting of (method (d)) and the like.

Hereinafter, the method (a) will be described. In addition, the manufacturing method of a polymer electrolyte is not limited to the following.
First, an oligomer capable of becoming a hydrophilic part oligomer (an oligomer containing a sulfoxidizable part) and a hydrophobic part oligomer are prepared using the monomer constituting the above-mentioned hydrophilic part oligomer and the monomer constituting the hydrophobic part oligomer. As a method of obtaining these oligomers, a method of condensing a monomer having a nucleophilic substituent such as a hydroxyl group at the end and a monomer having a leaving group such as a halogen-containing group at the end, a monomer having a leaving group The method etc. which add a catalyst inside and condense it are mentioned.

The polymerization reaction (condensation reaction) can be carried out in a molten state without using a solvent, but is preferably carried out in a suitable solvent. Examples of the solvent include aromatic hydrocarbon solvents, halogen solvents, ether solvents, ketone solvents, amide solvents, sulfone solvents, sulfoxide solvents and the like. Examples of the aromatic hydrocarbon solvent include benzene, toluene, xylene, 1,3,5-trimethylbenzene and the like. Examples of halogen solvents include dichlorobenzene, trichlorobenzene and the like. Examples of the ether solvents include tetrahydrofuran, dioxane, cyclopentyl methyl ether and the like. Examples of ketone solvents include methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone and the like. Examples of the amide solvents include N, N-dimethylacetamide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone and the like. Examples of sulfone solvents include sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane and the like. Examples of the sulfoxide solvents include dimethyl sulfoxide, diethyl sulfoxide and the like. These may be used alone or in combination of two or more.

In order to accelerate the reaction, a basic compound is usually used as a catalyst. As the basic compound, alkali metal salts, alkaline earth metal salts and the like are preferably used, and if exemplified, LiOH, NaOH, KOH, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO _{3 and the} like.

The reaction temperature of the polymerization reaction step may be appropriately set according to the polymerization reaction. Specifically, it may be set to 20 ° C. to 250 ° C. in the optimum use range, and more preferably 40 ° C. to 200 ° C. If the temperature is lower than 20 ° C., the reaction tends to be delayed, and if the temperature is higher than 250 ° C., the main chain tends to be easily cut. Although the reaction time of a polymerization reaction process is not specifically limited, Preferably it is 0.1 to 500 hours, More preferably, it is 0.5 to 300 hours.

As described above, after obtaining an oligomer capable of becoming a hydrophilic part oligomer and a hydrophobic part oligomer, these are chemically bonded to form a block copolymer. There is no restriction | limiting in particular as a method to chemically bond these oligomers and to make it block copolymer, It can determine suitably by the reactivity of the oligomer to superpose | polymerize. For the details of the polymerization method, general methods ("Polymer synthesis and reaction (2)", pp. 249-255, 1991, Kyoritsu Publishing Co., Ltd.) can be applied. Specifically, for example, a block copolymer is obtained by condensing an oligomer having a nucleophilic substituent such as a hydroxyl group at the end and an oligomer having a leaving group such as a halogen-containing group at the end in the presence of a basic compound. Allow to polymerize. Alternatively, block copolymers can be formed by condensing each oligomer having a halogen-containing group at its terminal in the presence of a transition metal.

Next, in the block copolymer obtained as described above, only the unit that can be a hydrophilic part is sulfonated. In this case, the relatively high electron density portion of the benzene ring is sulfonated. That is, a unit derived from the hydrophilic moiety oligomer and a unit derived from the hydrophobic moiety oligomer are obtained by reacting the block copolymer (obtained from the oligomer capable of becoming the hydrophilic moiety oligomer and the hydrophobic moiety oligomer) with the sulfonating agent. Block copolymer (polyelectrolyte) can be synthesized.

Examples of the sulfonating agent include chlorosulfonic acid, sulfuric anhydride, fuming sulfuric acid, sulfuric acid, acetyl sulfuric acid and the like, and chlorosulfonic acid and fuming sulfuric acid are preferable because they have appropriate reactivity.
A solvent may or may not be used in the sulfonation reaction. When a solvent is used, any solvent may be used as long as it is inert to the sulfinating agent, and examples thereof include hydrocarbon solvents and halogenated hydrocarbon solvents. Examples of hydrocarbon solvents include saturated aliphatic hydrocarbons, and linear or branched hydrocarbons having 5 to 15 carbon atoms are particularly preferable. From the viewpoint of solubility, pentane, hexane, heptane, octane and decane are preferable. More preferable. Examples of the halogenated hydrocarbon solvents include halogenated saturated aliphatic hydrocarbons and halogenated aromatic hydrocarbons. Examples of the halogenated saturated aliphatic hydrocarbon include monochloromethane, dichloromethane, trichloromethane, tetrachloromethane, monochloroethane, dichloroethane, trichloroethane, tetrachloroethane and the like, and dichloromethane is preferable in terms of ease of handling. Examples of the halogenated aromatic hydrocarbon include chlorobenzene, dichlorobenzene, trichlorobenzene and the like, and chlorobenzene is preferable in terms of ease of handling.

The reaction temperature of the sulfonation step may be appropriately set according to the reaction, and specifically, it may be set to -80 ° C to 200 ° C, which is the optimum use range of the sulfonation agent, and more preferably -50 ° C to- It is 150 ° C, more preferably -20 ° C to 130 ° C. If the temperature is lower than -80.degree. C., the reaction is delayed, the desired sulfonation tends not to progress to 100%, and if the temperature is higher than 200.degree. C., side reactions tend to occur.

The reaction time of the sulfonation step may be appropriately selected depending on the structure of the oligomer that can be a hydrophilic part oligomer, but it may be in the range of about 1 minute to 50 hours in general. If it is shorter than 1 minute, uniform sulfonation tends not to proceed, and if it is longer than 50 hours, side reactions tend to occur.

The amount of addition of the sulfonation agent in the sulfonation step is preferably 1 equivalent to 50 equivalents when the total amount (mole) of the sulfonated site contained in the oligomer capable of becoming a hydrophilic portion oligomer is 1 equivalent. If the amount is less than 1 equivalent, non-sulfonated sites tend to be generated, while if the amount is more than 50 equivalents, the main chain of the oligomer that can be a hydrophilic portion oligomer tends to be easily cut.

The concentration of the oligomer capable of becoming a hydrophilic portion oligomer in the sulfonation step is not particularly limited as long as the reaction proceeds uniformly when contacted with a sulfonating agent, but the oligomer capable of becoming a hydrophilic portion oligomer has side reactions such as molecular weight reduction It is preferable that it is 1 to 30 weight% with respect to the weight of the whole compound used for sulfonation reaction from the viewpoint of the cost superiority by not causing and solvent amount suppression.

In the above methods (b) to (d), according to the method described in JP-A-2012-229418, the ends of the hydrophobic portion oligomer and the hydrophilic portion oligomer or the terminal of the hydrophilic monomer having a sulfonic acid group are all halogen. It is also possible to use a method of polycondensation using a transition metal compound. As such a transition metal compound, a nickel compound, a palladium compound and a copper compound are preferably used, preferably a zero-valent nickel complex such as bis (1,5-cyclooctadiene) nickel, tetrakistriphenylphosphine nickel and the like. Is used. Alternatively, a divalent nickel complex such as dichlorobistriphenylphosphine nickel may be used in the presence of a reducing agent such as zinc.

<2. Glass non-woven fabric>
The glass non-woven fabric is obtained by irregularly intertwining glass fibers and processing it into a sheet. The glass nonwoven fabric in the present invention is characterized in that it contains glass fibers having an average diameter of 1 μm or less and is treated with a silicon compound binder or an epoxy compound binder. The glass nonwoven fabric having such features can provide a polymer electrolyte membrane having high mechanical strength, suppressing dimensional change at the time of containing water, and having excellent dry / wet cycle resistance.

When the average diameter of the glass fiber exceeds 1 μm, the dry / wet cycle resistance of the polymer electrolyte membrane tends to be lowered. Moreover, it is preferable that the average diameter of glass fiber is 0.8 micrometer or less.

The glass nonwoven fabric may further contain glass fibers having an average diameter of more than 1 μm and less than 10 μm. It is more preferable to mix glass fibers having a mean diameter of 1 μm or less with those having a mean diameter of more than 1 μm and less than 10 μm, since the rigidity of the glass non-woven fabric is improved and higher dry / wet cycle resistance is exhibited. The content of glass fibers having an average diameter of more than 1 μm and less than 10 μm is preferably 10 to 70% by weight with respect to a total of 100% by weight of glass fibers. If it is less than 10% by weight, the effect of rigidity improvement is small, and if it exceeds 70% by weight, the space between thick glass fibers tends to be spread, and the tensile strength tends to be reduced. It may not be possible to hold it.

Since the fiber diameter of glass fiber usually varies to some extent, an average value is used. More specifically, about 10 arbitrary fiber diameters in a glass nonwoven fabric are observed and measured with an optical microscope, and let the average value be an average diameter of glass fiber.

The range of 0.5 mm-20 mm is preferable, and, as for the average fiber length of the glass fiber which comprises a nonwoven fabric, it is more preferable to exist in the range of 2 mm-15 mm. If the average fiber length is less than 0.5 mm, the mechanical strength of the non-woven fabric is reduced, and the reinforcing effect of the electrolyte membrane tends to be reduced. On the other hand, when the average fiber length exceeds 20 mm, the dispersibility of the glass fiber at the time of forming the non-woven fabric is reduced, and the uniformity of thickness and uniformity of the area weight tend to be degraded. As a result, there is a risk that a non-woven fabric suitable for reinforcing the electrolyte membrane can not be obtained.

Since the polymer electrolyte to be compounded has a sulfonic acid group, the glass fiber is preferably made of acid resistant glass, so-called C glass or glass having acid resistance called alkali-containing glass from the viewpoint of durability. . Here, glass called C glass or alkali-containing glass is generally a glass having a composition having an alkali content of 0.8 to 20% by weight, and is excellent in acid resistance.

Although various compounds are known as binders, the glass non-woven fabric used in the present invention is treated with a silicon-based compound binder or an epoxy-based compound binder to strongly restrain glass fibers with each other. , The dimensional stability and strength of the non-woven fabric can be enhanced. In addition, the swelling resistance and the wet-wet cycle resistance of the reinforced polymer electrolyte membrane are improved. When a non-woven fabric is formed only with glass fibers, the dimensional stability and tensile strength of the non-woven fabric depend only on the entanglement of fibers. Therefore, the bonds between the fibers are weak, and as the polymer electrolyte is deformed, the glass fibers in close contact with the polymer electrolyte also move. That is, the binding force between the glass fibers is very weak, and the dimensional stability required for the electrolyte membrane of the fuel cell can not be obtained.

The binders may be used alone or in combination of two or more. Among the above-mentioned binders, an epoxy-based compound binder is preferable from the viewpoint that the dry / wet cycle resistance of the polymer electrolyte membrane is further improved because the glass fiber has strong binding power and high affinity with the polymer electrolyte.

As an example of a silicon type compound binder, what is generally called a silane coupling agent is mentioned first. Specific examples thereof include vinyltris (β-methoxyethoxy) silane, vinyltrichlorosilane, vinylsilane such as vinyltrimethoxysilane, acrylic silane such as γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-β Aminosilane such as-(aminoethyl) -γ-aminopropyltrimethoxysilane, epoxysilane such as γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-ureidopropyl Ureidosilanes such as triethoxysilane, chlorosilanes such as γ-chloropropyltrimethoxysilane, mercaptosilanes such as γ-mercaptopropyltrimethoxysilane, isocyanators such as γ-isocyanatopropyltrimethoxysilane Tosilane etc. are mentioned. Further, a reaction product of the above aminosilane and epoxysilane, a reaction product of aminosilane and isocyanate silane, and the like can also be used.

As silicon-based compound binders other than silane coupling agents, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, n-propyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, n- Alkyl silicates such as butyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane, n-dodecyltrimethoxysilane, polydimethylsiloxane, polydiethylsiloxane, polymethylphenylsiloxane And the like.

There is no particular limitation on the epoxy compound binder, and known ones can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, glycidyl ether type epoxy resin of bisphenol A propylene oxide adduct, hydrogenated bisphenol A type epoxy resin and the like can be mentioned.

When using an epoxy compound binder, a curing agent for epoxy resin is used in combination. As the curing agent, known ones can be used and, for example, diethylenetriamine, triethylenetetramine, diethylaminopropylamine, N-aminoethylpiperazine, benzyldimethylamine, tris (dimethylaminomethyl) phenol, metaphenylene diamine Amine compounds such as diaminodiphenylmethane, diaminodiphenyl sulfone, dicyandiamide, menthan diamine, xylene diamine, ethyl methyl imidazole, various polyamide resins, phthalic anhydride, maleic anhydride, dodecyl succinic anhydride, hexahydrophthalic anhydride, methyl anhydride There may be mentioned acid anhydrides such as nadic acid, biromellic acid anhydride, benzophenone tetracarboxylic acid anhydride, dichlorosuccinic acid anhydride and the like.

As a binder other than the silicon compound binder and the epoxy compound binder, for example, acrylic resin dispersion, acrylic resin emulsion, fluoro resin dispersion, fluoro resin emulsion, polyurethane dispersion, polyurethane emulsion, silicone resin dispersion, silicone resin emulsion Various liquid binders such as polyimide varnish, polyvinyl alcohol aqueous solution, colloidal silica dispersion, alkyl silicate, alkoxide of silicon or titanium, and titania sol are known.

After the treatment with the above-mentioned binder generally used as a binder, the treatment with the above-mentioned silane coupling agent may be further carried out. The general binder and the silane coupling agent exhibit reinforcing effects with independent mechanisms, so they can be used in combination, and their effects are synergistic.

The above-mentioned silicon-based compound binder or epoxy-based compound binder may contain an inorganic binder. As the inorganic binder, synthetic inorganic sol such as silica sol, alumina sol, titania sol (dispersed in water as fine particles, and becomes a gel after hardening by drying to form a gel), natural such as kaolin, clay, sepiolite, attapulgite, bentonite Mineral powder (dispersed in water and solidified when dried), Minced scale like mica, smectite, Silica flake, Silica-titania flake, Synthetic scale like alumina flake (Dispersed in water Inorganic binders such as those which are solidified upon drying to form a self-film) and silica fine particles are used. Among them, a synthetic inorganic binder with few impurities is preferable. Also, those having an average particle diameter of 0.01 to 2 μm, preferably 0.1 to 1 μm, more preferably 0.2 to 0.6 μm are used.

With regard to the amount of silicon compound binder or epoxy compound binder used, the amount of solid matter of the binder in the glass non-woven fabric is 0.5 to 10% (more preferably 2 to 9%) of the mass of the glass fiber It is preferable to be adjusted to be in the range.

The glass non-woven fabric used in the present invention can be produced, for example, by the following method.

In the first method, first, a liquid mixture containing glass fibers and a binder component that strengthens the bonds between the glass fibers is prepared (step (i)). As described above, glass fibers having a mean diameter of 1 μm or less, or a mixture of those having a mean diameter of 1 μm or less and a mean diameter of more than 1 μm and less than 10 μm are used. As the binder component, the above-mentioned silicon-based compound or epoxy-based compound is used. The liquid mixture of step (i) may contain a dispersant, a surfactant, a pH adjuster, a flocculant and the like. Next, a non-woven fabric containing glass fibers and a binder is formed from the liquid mixture (step (ii)). The non-woven fabric can be formed, for example, by a general wet sheet-forming method. After forming the non-woven fabric, heat treatment or the like may be performed if necessary. In step (ii), a non-woven fabric in which glass fibers are bound by a binder is obtained.

In the second method, first, glass fibers are used to form a non-woven fabric, for example, by a general wet sheet-forming method (step (I)). Next, the liquid containing the binder component is applied to the non-woven fabric and dried to strengthen the bond between the glass fibers (step (II)). Heat treatment may be performed at the time of drying. The application of the binder may be performed by immersing the non-woven fabric in the binder, or may be performed by impregnating the non-woven fabric with the binder. In the step (II), in order to suppress the formation of a film between glass fibers, it is preferable to remove the excess binder after applying the binder.

The first method has the advantage that the manufacturing process is simple. On the other hand, the second method has the advantage that the binder can be concentrated at the intersections of glass fibers, and a high effect can be obtained with a small amount of binder.

Since the thickness of the polymer electrolyte membrane of the present invention is preferably 300 μm or less as described later, it is preferable that the glass non-woven fabric to be composited with this is thin within the range of improving the mechanical strength. The thickness (measured value at a pressure of 20 kP) is preferably 50 μm or less, and more preferably 30 μm or less. Moreover, from the point of strength improvement, 5 micrometers or more are preferable, and, as for the thickness of the said glass nonwoven fabric, 10 micrometers or more are more preferable. The thickness of the non-woven glass fabric is a value obtained by applying an even pressure (20 kPa) to the whole non-woven glass fabric and measuring the thickness at any about 10 places of the non-woven glass fabric using a dial gauge.

The weight per unit area (weight per unit area) of the non-woven fabric is preferably ² to 50 g / m ² , and more preferably 3 to 25 g / m ² . If the weight per unit area is less than 2 g / m ² , the entanglement of the glass fibers is reduced, and the tensile strength tends to be reduced. On the other hand, if the weight per unit area exceeds 50 g / m ² , there is a possibility that the reinforcing material of the electrolyte membrane may become too thick, and if the density is increased by a press or the like to make it thinner, May break and become short, and the tensile strength may decrease.

The glass non-woven fabric preferably has a porosity of 80% or more, more preferably in the range of 85 to 95%, from the viewpoint of improving mechanical strength and minimizing the decrease in proton conductivity due to compounding. . The porosity of the glass nonwoven fabric can be calculated by calculating the specific gravity from the volume and weight of the glass nonwoven fabric and dividing this by the true specific gravity of the glass.

<3. Polymer electrolyte membrane>
The polymer electrolyte membrane of the present invention is a composite of the polymer electrolyte and the glass nonwoven fabric. That is, the polymer electrolyte membrane of the present invention has a unit substantially derived from a hydrophobic portion oligomer having a main chain mainly composed of an aromatic ring group, and a sulfonic acid group, having substantially no sulfonic acid group, It is a polymer electrolyte membrane in which a polymer electrolyte having as a main chain a unit derived from a hydrophilic moiety oligomer mainly composed of an aromatic ring group and a glass nonwoven fabric, wherein the glass nonwoven fabric has an average diameter Is 1 μm or less, and is treated with a silicon compound binder or an epoxy compound binder.

To combine the polymer electrolyte and the glass non-woven fabric means to integrate the both, that is, to embed the glass non-woven fabric in the polymer electrolyte. As the method of combination, conventionally known methods can be applied. As a simple method, a glass non-woven fabric is fixed on a substrate such as glass, a solution of a polymer electrolyte is cast thereon, and the solvent is removed; first, a solution of a polymer electrolyte is cast on a substrate such as glass A method of removing a solvent after placing a non-woven glass fabric thereon and further casting a solution of the polyelectrolyte; dip the non-woven glass fabric in the solution of the polyelectrolyte to form a polyelectrolyte in the voids of the non-woven glass fabric For example, a method of removing the solvent in a state in which the glass non-woven fabric containing the solution is spread in the vertical state is exemplified. Such a method is common in the method used when producing the composite material of a nonwoven fabric and resin. In addition, a method of thermocompression bonding a polymer electrolyte and a glass non-woven fabric; a method of sandwiching a glass non-woven fabric between two semi-solid state polymer electrolytes containing a solvent, pressing, drying and the like may be applied.

The removal of the solvent can be carried out by drying preferably at a temperature of 10 to 200 ° C, more preferably 40 to 150 ° C. When the glass non-woven fabric containing the solution is dried in a sheet, it is preferable to set the drying temperature to about 45 to 130 ° C. and to dry for 1 hour to 20 hours. In addition, as a solvent used for preparation of the solution of a polymer electrolyte, for example, dimethylsulfoxide, N, N-dimethylacetamide, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, N-methyl Pyrrolidone etc. are mentioned. As described above, the polymer electrolyte membrane of the present invention in which the polymer electrolyte and the glass nonwoven fabric are combined can be obtained.

As a polymer electrolyte, the above-mentioned polymer electrolyte may be used independently, and another polymer electrolyte may be mixed and used. In addition, the polymer electrolyte membrane of the present invention may contain additives other than the above-mentioned polymer electrolyte and the glass non-woven fabric. For example, various additives such as an antioxidant for preventing resin deterioration, an antistatic agent for improving handling in molding processing as a film, a lubricant and the like can be mentioned, and the processing and performance as an electrolyte membrane are affected. It can use suitably in the range which does not exert. From the viewpoint of proton conductivity, in the polymer electrolyte membrane of the present invention, it is preferable that the above-mentioned polymer electrolyte is a main component that occupies 70% by weight or more of the whole polymer electrolyte membrane.

Further, after obtaining the electrolyte membrane, treatment such as biaxial stretching may be performed to control molecular orientation and the like, or heat treatment may be performed to control the degree of crystallization and the residual stress. Further, appropriate chemical treatment may be performed at the time of film formation. The chemical treatment includes, for example, crosslinking to increase the strength of the electrolyte membrane, addition of a protic compound to increase conductivity, addition of a trace amount of polyvalent metal ion for improving durability and ion crosslinking, etc. Be In any case, a polymer electrolyte membrane manufactured by using the above-mentioned polymer electrolyte in combination with a conventionally known technique is also within the scope of the present invention.

The thickness of the polymer electrolyte membrane can be selected arbitrarily according to the application. For example, in consideration of reducing the resistance of the polymer electrolyte membrane when used as a fuel cell, the thinner the thickness of the polymer electrolyte membrane, the better. On the other hand, considering the gas barrier property of the polymer electrolyte membrane, the handling property, the tear resistance at the time of bonding with the electrode, etc., it may not be preferable if the thickness of the polymer electrolyte membrane is too thin. In consideration of these, the thickness of the polymer electrolyte membrane is preferably 5 μm or more, more preferably 10 μm or more, and preferably 300 μm or less, more preferably 100 μm or less. When importance is attached to the output as a fuel cell, the thickness is preferably 10 μm to 50 μm. If the thickness of the polymer electrolyte membrane is 5 μm or more and 300 μm or less, the production is easy, the balance between membrane resistance and mechanical properties is well taken, and the handling property when processed as a fuel cell material is also excellent. The thickness of the polymer electrolyte membrane can be determined by the measurement method described in the examples.

The ion exchange capacity (IEC) of the polymer electrolyte membrane can be adjusted by the IEC of the polymer electrolyte. For example, when the polymer electrolyte membrane contains materials other than the polymer electrolyte and the glass non-woven fabric, the IEC as the polymer electrolyte membrane is lowered thereby, so that the IEC of the polymer electrolyte membrane is set to a higher value, etc. It can.

The IEC of the polymer electrolyte membrane is 1.0 meq. / G or more is preferable, and 1.5 meq. More preferably at least 3.5 meq. / G or less is preferable, and 3.0 meq. It is more preferable that it is / g or less. IEC is 1.0 eq. If it is smaller than / g, high proton conductivity tends to be difficult to develop, and 3.5 meq. When it is larger than 1 g, swelling with water tends to lower mechanical strength and make it difficult to have sufficient strength. The IEC of the polymer electrolyte membrane can be determined by the measurement method described in the examples.

<4. Membrane / Electrode Assembly, Fuel Cell>
The fuel cell membrane / electrode assembly (hereinafter, the membrane / electrode assembly is referred to as "MEA") according to the present invention is obtained by forming an electrode catalyst layer on the polymer electrolyte membrane of the present invention.

The electrode catalyst used in the present invention may be any electrode catalyst conventionally known to those skilled in the art, as long as it contains a conductive catalyst carrier and a catalytically active substance supported on the conductive catalyst carrier. The other specific configuration is not particularly limited. Specifically, a catalyst active against the electrode reaction of the fuel cell is used. On the anode side, a catalyst having the ability to oxidize fuel (such as hydrogen or methanol) is used.

As the conductive catalyst support, carbon supports having high surface area such as carbon black, ketjen black, activated carbon, carbon nanohorns, carbon nanotubes and the like are preferable from the viewpoint of catalyst supporting ability, electron conductivity, electrochemical stability and the like.

Specific examples of the catalytically active substance include platinum, cobalt, ruthenium and the like, and these may be used alone or as an alloy containing at least one of these, or as an arbitrary mixture. Particularly in consideration of the oxidizing ability of the fuel, the reducing ability of the oxidizing agent, and the durability, platinum or an alloy containing platinum is preferable. These may be composed of three or more components using iron, tin, a rare earth element or the like, as needed, in order to stabilize and prolong the life.

The electrode catalyst layer can be prepared by first preparing a catalyst ink containing a polymer electrolyte, an electrode catalyst and a solvent, applying the catalyst ink on a support, and removing the solvent. As the polymer electrolyte used for the catalyst ink, perfluorocarbon sulfonic acid-based electrolytes, hydrocarbon-based polymer electrolytes (for example, sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfonated, conventionally used) Polysulfone, sulfonated polyimide, sulfonated polyphenylene sulfide) can be mentioned. Any solvent can be used without limitation as long as it can dissolve the polymer electrolyte and does not poison the fuel cell catalyst.

The catalyst ink may contain additives such as a non-electrolytic binder, a water repellent, a dispersant, a thickener, and a pore former as needed. Moreover, as these additives, those conventionally known to those skilled in the art can be used, and the other specific configurations are not particularly limited.

The coating method shown below can be used for the catalyst ink prepared by the said composition and method according to a viscosity and the kind of base material. The coating method may be any coating method known to those skilled in the art, for example, a method using a knife coater, a bar coater, a spray, a dip coater, a spin coater, a roll coater, a die coater, a curtain coater, screen printing, etc. Although it can list, it is not limited to these. The other specific configuration is not particularly limited. When a polymer film is used as the substrate, the fuel cell catalyst layer transfer sheet can be used, and when a conductive porous sheet is used as the substrate, a fuel cell gas diffusion electrode can be manufactured.

An MEA can be produced by applying the catalyst ink to the polymer electrolyte membrane of the present invention by the above method, or by pressing the catalyst layer transfer sheet and peeling off the polymer film. The MEA can also be produced by bonding a conductive porous sheet to the polymer electrolyte membrane of the present invention.

Such MEA can be used, for example, in a fuel cell, in particular, a polymer electrolyte fuel cell. A fuel cell using the polymer electrolyte membrane of the present invention is also included in the scope of the present invention.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining the disclosed technical means are also disclosed. It is included in the technical scope.

Hereinafter, the embodiment of the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail.

Each measurement was performed as follows.
(Measurement of molecular weight)
The molecular weight was measured by the GPC method. The conditions are as follows.
GPC measuring device: HLC-8220 (made by Tosoh Corporation)
Column: Two SuperAW4000 and SuperAW 2500 (manufactured by Showa Denko KK) are connected in series Column temperature: 40 ° C.
Mobile phase solvent: NMP (N-methyl pyrrolidone, added to 10 mmol / dm ^{3 of} LiBr)
Solvent flow rate: 0.3 mL / min
Standard substance: TSK standard polystyrene (made by Tosoh Corporation)
Hereinafter, the number average molecular weight converted to standard polystyrene is represented as Mn, and the weight average molecular weight converted to standard polystyrene is represented as Mw.

(Measurement of thickness of polymer electrolyte membrane)
The thickness of nine places of the polymer electrolyte membrane was measured using a digital thickness meter (PDN-20) manufactured by Peacock, and the average value was taken as the thickness.

(Measurement of ion exchange capacity)
As a measurement sample, 10 to 20 mg of the membrane after acid treatment was cut out, dried under reduced pressure at 80 ° C., and the dry weight (W _dry ) was measured. The ion group was converted from H ⁺ form to Na ⁺ form by immersing the membrane in saturated aqueous NaCl solution (30 mL) at room temperature for 24 hours. After that, HCl contained in the solution obtained is quantified by 0.01 M NaOH aqueous solution using potentiometric automatic titrator AT-510 (manufactured by Kyoto Denshi Kogyo Co., Ltd.), and ion exchange capacity IEC value is calculated using the following formula. Calculated. Two samples were prepared for the same membrane, and the average value of two measurements was taken as the calculated IEC value by titration.

(Measurement of swelling rate)
A sample of a polymer electrolyte membrane cut to about 2 cm × 3 cm was prepared and immersed in pure water at room temperature for 6 hours. The planar direction, vertical direction dimensional change, and weight of the sample immediately after immersion and the sample which was vacuum dried at 100 ° C. for 2 hours to be in the dry state were measured, and the rate of change was calculated. For the planar direction, the dimensional change of the four sides was measured, and the average value was taken as the result. In the vertical direction (film thickness direction), the dimensional change of three points in the plane was measured, and the average value was taken as the result.

(Evaluation of dry / wet cycle resistance)
A sample of a polymer electrolyte membrane cut to about 6.5 cm × 6.5 cm was prepared, and a silicon packing and a gas diffusion layer (manufactured by SGL Carbon Co., Ltd.) were placed on both sides of this to prepare a sample. This sample was incorporated into a commercially available Japan Automobile Research Institute (JARI) standard fuel cell and fixed with 4 N · m tightening pressure using 8 screws. A pressure of 0.2 MPa was applied to this cell with nitrogen gas, and it was confirmed that there was no leak because the pressure did not decrease for 15 minutes. In the characterization, hydrogen was flowed to one side of the cell and argon was flowed to the other side at a flow rate of 30 ml / min. The respective gases were exchanged at 80 ° C. while maintaining the dry state (0% RH) and the wet state (100% RH) for 2 minutes, and a dry-wet cycle test was performed. The amount of hydrogen transmitted to the argon side through the polymer electrolyte membrane was quantified by gas chromatography every three cycles. The result is the number of cycles until the hydrogen permeation coefficient starts to rise sharply due to rupture of the membrane.

(Glass non-woven fabric used)
A glass nonwoven fabric having the properties shown in Table 1 was prepared and used.

(Production Example 1)
In a 500 mL three-necked flask equipped with a thermometer and a stirrer, 4,4-dichlorobenzophenone (75 g, 300 mmol) and 30% fuming sulfuric acid (400 g, 1.5 mol) were added. Heat to 130 ° C. and continue stirring for 6 hours. After cooling to room temperature, the reaction solution was added little by little to ice water. After neutralization by adding an aqueous solution of NaOH, the precipitated white solid was collected by filtration. By drying at 105 ° C. under reduced pressure, 112 g of a sulfonic acid group-containing monomer represented by the following formula was obtained.

(Production Example 2)
In a 500 mL four-necked flask fitted with a reflux tube and a Dean Stark tube, 4,4'-dichlorodiphenyl sulfone (31.6 g, 110 mmol), 4,4'-dihydroxybenzophenone (21.4 g, 100 mmol), potassium carbonate (21.4 g, 100 mmol) 20.7 g (150 mmol), dimethylacetamide (200 mL), and toluene (50 mL) were added. The mixture was heated to 170 ° C. and stirring was continued for 35 hours while removing the water formed. The 4,4'- dichloro diphenyl sulfone (0.5g) was added and it stirred for further 5 hours. The mixture was filtered using filter paper to remove excess potassium carbonate, and then the filtrate was poured into 500 mL of methanol to reprecipitate the product. The product is dried at 70 ° C. under reduced pressure for 4 hours, then washed twice with 500 mL of pure water at 60 ° C., and once with 500 mL of methanol at 60 ° C., overnight under vacuum at 70 ° C. The resultant was dried to obtain 41.5 g of a hydrophobic part oligomer of the following formula. The molecular weight by GPC was Mn = 5,400 and Mw = 13,900.

(Production Example 3)
A sulfonic acid group-containing monomer (24 g, 52.7 mmol) obtained in Production Example 1 and a hydrophobic moiety oligomer obtained in Production Example 2 were added to a 1 L four-necked flask equipped with a mechanical stirrer, a reflux condenser, and a Dean Stark pipe. 16 g), dimethyl sulfoxide (480 mL), and toluene (120 mL) were added to the nitrogen atmosphere and heated to 170 ° C. for 3 hours for azeotropic dehydration. After distilling off toluene at 170 ° C., the mixture was cooled to 80 ° C., bis (1,5-cyclooctadiene) nickel (20 g) was added, and the mixture was stirred at the temperature for 2 hours. The reaction solution was poured into 700 mL of methanol for reprecipitation, and then the solid content was washed twice with 6 N hydrochloric acid (600 mL), and then repeatedly washed with pure water until the pH of the washing became 7. The solid content was dried at 105 ° C. under reduced pressure overnight to obtain a polymer electrolyte of the following formula (33.2 g). The polymer electrolyte was pulverized with a grinder, washed with methylene chloride and methanol, and dissolved in dimethyl sulfoxide to obtain a polymer electrolyte solution having a solid content concentration of about 12%. The obtained polymer electrolyte was separately formed into a film as shown in Comparative Example 1, and when the molecular weight was measured by GPC, it was Mn = 85,100 and Mw = 177,000. Moreover, ion exchange capacity is 2.06 meq. It was / g.

( Comparative example 3 )
The polymer electrolyte solution prepared in Production Example 3 was coated on a glass plate by a bar coater. After the glass nonwoven fabric A (11 cm × 10 cm) of Table 1 was gently placed on the coated film so that bubbles did not mix, the polymer electrolyte solution of Production Example 3 was coated again with a bar coater. The obtained composite film was dried at 120 ° C. for 12 hours using a hot plate while being applied to a glass substrate. The membrane was removed from the glass plate, washed with 6 N hydrochloric acid and then with distilled water, the surface water was wiped off, and dried at 60 ° C. for 30 minutes to obtain a polymer electrolyte membrane A. The thickness, ion exchange capacity and swelling ratio of the polymer electrolyte membrane A were measured by the above-mentioned method. The results are summarized in Table 2.

(Examples 2 , 6, 7 and Comparative Examples 4 to 6 )
Polymer electrolyte membranes B to G were obtained in the same manner as in Comparative Example 3 except that glass non-woven fabrics B to G were used. The thickness of the polymer electrolyte membrane, the ion exchange capacity, the swelling ratio, and the wet-wet cycle resistance were measured by the above-mentioned method. The results are summarized in Table 2. Further, the results of the wet / dry cycle resistance test of the polymer electrolyte membrane F are shown in FIG.

(Comparative example 1)
An electrolyte membrane was produced using the polymer electrolyte solution of Production Example 3 without using a glass non-woven fabric. Thickness, ion exchange capacity, swelling ratio, and wet-wet cycle resistance were measured by the above-mentioned method. The results are summarized in Table 2. Further, the results of the dry / wet cycle resistance test are shown in FIG. 1 in comparison with the polymer electrolyte membrane F.

(Comparative example 2)
A polymer electrolyte membrane H was obtained in the same manner as in Comparative Example 3 except that the glass nonwoven fabric H was used. The thickness of the polymer electrolyte membrane, the ion exchange capacity, the swelling ratio, and the wet-wet cycle resistance were measured by the above-mentioned method. The results are summarized in Table 2.

In each embodiment, as the flat Hitoshi径glass fiber is 1 [mu] m or less, it is those mean diameter were mixed with those of less than 10μm exceed 1 [mu] m, and a glass nonwoven fabric has been treated with an epoxy compound binder I use it. Comparative Example 1 is a non-reinforcing film not using a glass non-woven fabric. In the comparative example 2, although the thing of 1 micrometer or less of average diameters of glass fiber is used, the glass nonwoven fabric which has not been surface-treated by the binder is used. The polymer electrolyte membrane of each embodiment, compared with the ratio Comparative Examples 1-6, it is found to have resistance to swelling with improved, and the wet and dry cycle durability.

Claims (5)

Substantially no sulfonic acid group, the main chain is Ri Do from mainly an aromatic ring group, units derived from a hydrophobic portion oligomer comprising as at least one repeating unit of the structure according to the following general formula group (4) ,

(Wherein, Ar represents a divalent aromatic group. When there are a plurality of Ar, they may be the same or different).
and,
Having a sulfonic acid group, the main chain is Ri Do from mainly an aromatic ring group, units derived from the hydrophilic portion oligomer comprising as at least one repeating unit of the structure according to the following general formula group (1)

(Wherein, Ar ¹ represents a divalent group having any of the structures described in the following formula group (2), and the divalent group may have a substituent. Ar ² is And represents a divalent aromatic group having at least one sulfonic acid group, and when a plurality of Ar ¹ or Ar ² are present, they may be the same or different, n is an integer of 1 to 4, X represents -O- or -S-, and Y represents -SO ₂ -or -CO-).

A polymer electrolyte membrane composed of a polymer electrolyte having a main chain and a glass nonwoven fabric,
The glass nonwoven fabric, the following glass fibers and the average diameter of an average diameter of 1 [mu] m comprises glass fibers is less than 10μm exceed 1 [mu] m, and the polymer electrolyte membrane, characterized in that it is treated with Et epoxy compound binder . Ar ² has a structure of any of described in the following formula group (3), and characterized in that the sulfonic acid group is a divalent aromatic group having at least one, according to claim 1 Polymer electrolyte membrane.

The ion exchange capacity is 1.5 to 3.5 meq. The polymer electrolyte membrane according to claim 1 or 2 , characterized in that it is / g. A membrane-electrode assembly for a fuel cell, using the polymer electrolyte membrane according to any one of claims 1 to 3 . A fuel cell using the polymer electrolyte membrane according to any one of claims 1 to 3 .

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