JP2006286521A - Polymer electrolyte fuel cell, direct liquid fuel cell, resin composition used for direct methanol fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for a proton conductive binder capable of closely bonding a hydrocarbon electrolyte membrane and a gas diffusion electrode and providing high proton conductivity to the inside of the electrode in a proton conductive polymer electrolyte membrane-electrode assembly useful for a constitution material of a polymer electrolyte fuel cell, a direct liquid fuel cell, and a direct methanol fuel cell. <P>SOLUTION: The resin composition for the binder containing a polymer compound containing a proton conductive group and a polymer compound not containing the proton conductive group contains two or more kinds selected from (A) a polymer compound containing the proton conductive group and not containing a styrene family thermoplastic elastomer, (B) a styrene family thermoplastic elastomer containing a proton conductive group, and (C) a styrene family thermoplastic elastomer not containing the proton conductive group, and (C) is an essential ingredient. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin composition for use in a polymer electrolyte fuel cell, a direct liquid fuel cell, and a direct methanol fuel cell, especially for carbonization with low methanol permeability and / or extremely high proton conductivity. The present invention relates to a proton conductivity imparting agent suitable for a hydrogen-based electrolyte membrane.

  Polymer compounds containing proton-conducting substituents such as sulfonic acid groups can be used in polymer electrolyte fuel cells, direct liquid fuel cells, direct methanol fuel cells, humidity sensors, gas sensors, electrochromic display elements, etc. Used as an element material. Among these, solid polymer fuel cells, direct liquid fuel cells, and direct methanol fuel cells are expected as one of the pillars of new energy technology. Solid polymer fuel cells, direct liquid fuel cells, and direct methanol fuel cells that use electrolyte membranes made of polymer compounds with proton-conducting substituents can be operated at low temperatures and can be reduced in size and weight. Application to mobile bodies such as automobiles, home cogeneration systems, and small-sized private-use equipment is being studied. In particular, direct methanol fuel cells that use methanol directly as fuel have a simple structure, easy fuel supply and maintenance, and high energy density. It is expected to be applied to small portable devices for private use such as laptop computers.

  Perfluorocarbon sulfonic acid membranes typified by Nafion (registered trademark) have been widely studied as proton conductive electrolyte membranes used in polymer electrolyte fuel cells, direct liquid fuel cells, and direct methanol fuel cells. ing. The perfluorocarbon sulfonic acid membrane has high proton conductivity and excellent chemical stability such as acid resistance and oxidation resistance. However, there is a problem that the raw material used is high and is very expensive due to complicated manufacturing processes. Furthermore, permeation (also referred to as crossover) of a hydrogen-containing liquid such as methanol is large, and a so-called chemical short reaction occurs. As a result, the cathode potential, fuel efficiency, cell characteristics and the like are lowered, and it is difficult to directly use as an electrolyte membrane of a methanol fuel cell. Moreover, there is a concern that fuel may be lost due to crossover even when power is not generated.

  From such a background, it has been studied to use a relatively excellent hydrocarbon proton conductive polymer electrolyte membrane as a proton conductive polymer electrolyte membrane in terms of properties and performance (Patent Document 1, Patent Document 2). However, even when the hydrocarbon proton conductive polymer electrolyte membrane is used as described above, the perfluorocarbon sulfonic acid resin is often used as the binder / binder to be included in the gas diffusion electrode. ing. However, when the hydrocarbon proton conductive polymer electrolyte membrane is used as the electrolyte membrane, and the perfluorocarbon sulfonic acid resin is used as the binder / binder to be contained in the gas diffusion electrode, the hydrocarbon proton conductive material is used. It was discovered that at the bonding interface between the polymer electrolyte membrane and the gas diffusion electrode, the familiarity of both deteriorates and the bonding strength is greatly reduced. When the bonding strength between the electrolyte membrane and the gas diffusion electrode is reduced in this way, peeling occurs during power generation, and the battery performance is likely to be deteriorated, resulting in a great hindrance to practical use.

In addition, there are reports of attempts to bond with a sulfonic acid-modified hydrocarbon proton-conductive polymer electrolyte membrane or a sulfonic acid-modified styrene-based elastomer composition so that it is suitable for a hydrocarbon-based proton conductive polymer electrolyte membrane. It is not easy to achieve both proton conductivity and adhesiveness of a sulfonic acid-modified composition (Patent Document 3, Patent Document 4, and Patent Document 5).
Japanese Patent Laid-Open No. 6-68899 Japanese Patent Laid-Open No. 11-310649 JP 2002-164055 A JP 2002-367626 A Japanese National Patent Publication No. 10-503788

  The present invention has been made in view of the above-mentioned problems of the prior art, and has excellent proton conductivity and hydrocarbon proton conductivity useful as a constituent material for polymer electrolyte fuel cells and direct methanol fuel cells. It is an object of the present invention to easily provide a proton conductive polymer electrolyte material having good adhesion to a conductive polymer electrolyte membrane.

  As a result of earnestly performing the present invention for such problems, the inventors have invented the following.

(1) The first of the present invention is
A resin composition for a binder used for a polymer electrolyte membrane-electrode assembly containing a proton conductive group of a solid polymer fuel cell, a direct liquid fuel cell, and a direct methanol fuel cell, A resin composition for a binder, wherein the binder resin composition comprises a polymer compound containing a proton conductive group and a polymer compound not containing a proton conductive group,
It is.

(2) The second aspect of the present invention is
The binder resin composition is
(A) a polymer compound containing a proton conductive group, excluding a styrene-based thermoplastic elastomer,
(B) a styrenic thermoplastic elastomer containing a proton conductive group,
(C) a styrenic thermoplastic elastomer containing no proton conductive group,
A resin composition for a binder according to (1), which is a resin composition comprising two or more selected from the above and containing (C) as an essential component,
It is.

(3) The third aspect of the present invention is
The ratio of the monomer component forming the polymer main chain of the styrenic thermoplastic elastomer is such that the monomer component having a styrene skeleton is 10 mol% or more and 70 mol% or less (1) to (2) The resin composition for a binder according to any one of
It is.

(4) The fourth aspect of the present invention is
The chemical structural formula of the monomer component having no styrene skeleton of the styrene elastomer is a group represented by the following general formula (1)

（Ｒ₁〜Ｒ₁₂は、Ｈ、低級アルキル、低級フルオロアルキルからなる群から選ばれ、Ｒ₁〜Ｒ₁₂は独立であって、互いに同一でも異なっていても良い、ｌ，ｍ，ｎは０以上である）で表されることを特徴とする、（１）〜（３）のいずれかに記載の、結着剤用樹脂組成物、
である。

(R _{1 to} R ₁₂ are selected from the group consisting of H, lower alkyl, and lower fluoroalkyl, and R _{1 to} R ₁₂ are independent and may be the same or different. L, m, and n are 0. The resin composition for a binder according to any one of (1) to (3), characterized in that
It is.

(5) The fifth aspect of the present invention is
The ion exchange capacity of the resin composition for binder is 1.0 meq / g or more, The resin composition for binder according to any one of (1) to (4),
It is.

(6) The sixth aspect of the present invention is
The resin composition for a binder according to any one of (1) to (5), wherein the proton conductive group contains a sulfonic acid group,
It is.

(7) The seventh of the present invention is
Furthermore, a resin composition for a binder according to any one of (1) to (6), wherein a super strong acid group-containing fluoropolymer is added,
It is.

(8) The eighth aspect of the present invention is
The resin composition for a binder according to (7), wherein the super strong acid group-containing fluoropolymer is Nafion (registered trademark),
It is.

(9) The ninth of the present invention is
The resin composition for a binder according to any one of (1) to (8), wherein the polymer electrolyte membrane containing the proton conductive group contains polyphenylene sulfide (PPS),
It is.

(10) The tenth aspect of the present invention is
A polymer electrolyte membrane comprising the resin composition for a binder according to any one of (1) to (9),
It is.

(11) The eleventh aspect of the present invention is
A polymer electrolyte membrane-electrode composite comprising the resin composition for a binder according to any one of (1) to (9),
It is.

(12) The twelfth aspect of the present invention is
A solid polymer fuel cell, a direct liquid fuel cell, or a direct methanol fuel cell, comprising the binder resin composition according to any one of (1) to (9),
It is.

The resin composition for a binder of the present invention is
Adhesion is expressed mainly by styrenic thermoplastic elastomer,
Proton conductivity is expressed by a polymer compound containing a proton conductive group. That is, the resin composition for a binder of the present invention has functions of both adhesiveness and proton conductivity.

  The resin composition for a binder of the present invention makes it possible to achieve both proton conductivity and adhesiveness, which have been problems in the prior art.

Therefore, the present invention
Hydrocarbon electrolyte membranes that are used in solid polymer fuel cells, direct liquid fuel cells, direct methanol fuel cells, especially for resin compositions that have particularly low methanol permeability and / or extremely high proton conductivity It is possible to provide a resin composition for a binder suitable for the above.

  By using the present binder resin composition, in a proton conductive polymer electrolyte membrane-electrode assembly useful as a constituent material of a solid polymer fuel cell, a direct liquid fuel cell, and a direct methanol fuel cell, An object of the present invention is to provide a proton conductive resin composition for a binder capable of satisfactorily adhering a hydrocarbon-based electrolyte membrane to a gas diffusion electrode and imparting good proton conductivity to the inside of the electrode.

According to the binder resin composition of the present invention,
At the bonding interface between the hydrocarbon-based proton conductive polymer electrolyte membrane and the gas diffusion electrode, a familiarity between them and a high bonding strength can be achieved.

A molded article obtained by casting the resin composition for a binder of the present invention;
When a 90 ° peel test with a hydrocarbon-based polymer electrolyte membrane is performed and the peel strength is measured, it can be seen that a result of 2.0 N / cm or more can be achieved.

  According to the resin composition for a binder of the present invention, the possibility that the bonding strength between the electrolyte membrane and the gas diffusion electrode is lowered is remarkably reduced, and the possibility that the peeling occurs during power generation is remarkably reduced. The battery performance is significantly reduced, which is beneficial for its practical use.

  The resin composition for a binder of the present invention is also suitable for a hydrocarbon proton conductive polymer electrolyte membrane. The proton conductive polymer electrolyte membrane-electrode assembly exhibits high proton conductivity and good adhesion by the binder that bonds the binder and / or catalyst at the membrane-electrode interface to the catalyst carrier. Became possible.

  These have excellent proton conductivity and good adhesiveness, and are a binder for proton conductive polymer electrolyte membranes or membrane-electrode interfaces of solid polymer fuel cells, direct liquid fuel cells, and direct methanol fuel cells. And / or useful as a binder for binding the catalyst to the catalyst support.

  The resin composition comprising a thermoplastic elastomer and a proton conductive polymer electrolyte as essential components for use in the solid polymer fuel cell, direct liquid fuel cell and direct methanol fuel cell of the present invention will be described.

<Resin composition for binder>
The resin composition for a binder of the present invention is
Binder / binder at the membrane-electrode interface, and / or
Binders and binders that bind the catalyst to the catalyst carrier,
As used.

  The binder / binder is required to achieve both proton conductivity and adhesion / tackiness. As will be described below, the binder resin composition of the present invention has both proton conductivity and adhesiveness / tackiness.

  The resin composition for a binder of the present invention includes a polymer compound containing a proton conductive group and a polymer compound not containing a proton conductive group.

<Proton conductive group>
The proton conductive substituent contained in the proton conductive polymer electrolyte of the present invention can be used as long as it dissociates protons in a water-containing state. For example, a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, a phenolic hydroxyl group, a sulfonimide group and the like can be exemplified. In particular, the ease of introduction of a proton conductive substituent and the proton conductivity of the obtained proton conductive polymer electrolyte In view of the above, a sulfonic acid group is preferable. The ion exchange capacity of the proton conductive polymer electrolyte derived from the content of the proton conductive substituent is preferably 0.3 meq / g, more preferably 0.5 meq / g or more. If the ion exchange capacity is lower than 0.3 meq / g, the desired proton conductivity may not be exhibited, which is not preferable.

<Styrenic thermoplastic elastomer>
The styrenic thermoplastic elastomer is a thermoplastic elastomer characterized by containing styrene as a monomer that forms a polymer main chain. For example,
Polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer (SEBS),
Polystyrene-poly (ethylene-propylene) -polystyrene triblock copolymer (SEPS),
Polystyrene-polyisobutylene-polystyrene triblock copolymer (SIBS),
Polystyrene-polybutadiene-polystyrene triblock copolymer (SBS),
Polystyrene-polyisoprene-polystyrene (SIS) triblock copolymer,
Polystyrene-poly (ethylene-propylene) polymer (SEP),
Polystyrene-poly (ethylene-ethylene-propylene) -polystyrene polymer (SEEPS),
In particular, from the viewpoint of adhesion, polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer (SEBS),
Polystyrene-poly (ethylene-propylene) -polystyrene triblock copolymer (SEPS),
Polystyrene-polyisobutylene-polyethylene triblock copolymer (SIBS) and the like are preferable.

  The solvent for dissolving the thermoplastic elastomer may be 1,2-dichloroethane, cyclohexane, methylene chloride, chloroform, etc., but is not particularly limited. Of these, 1,2-dichloroethane and cyclohexane are particularly preferred because they are commercially available in large quantities at low cost.

One aspect of the styrenic thermoplastic elastomer used in the resin composition of the present invention is:
The chemical structural formula of the monomer component having no structural unit styrene skeleton is represented by the following general formula (1):

（Ｒ₁〜Ｒ₁₂は、Ｈ、低級アルキル、低級フルオロアルキルからなる群から選ばれ、Ｒ₁〜Ｒ₁₂は独立であって、互いに同一でも異なっていても良い、ｌ，ｍ，ｎは０以上である）で表されることを特徴とする高分子化合物を列挙できる。これらは単独または２種類以上混合して用いても良いし、あらゆる比率のランダムあるいはブロック共重合体等のブロック共重合体が制限なく採用される。これらは特に制限されるものではないが工業的に入手しやすいためにトリブロック重合体が好ましい。

(R _{1 to} R ₁₂ are selected from the group consisting of H, lower alkyl, and lower fluoroalkyl, and R _{1 to} R ₁₂ are independent and may be the same or different. L, m, and n are 0. The polymer compounds characterized by the above can be listed. These may be used alone or in admixture of two or more, and any ratio of random or block copolymers such as block copolymers may be used without limitation. These are not particularly limited, but triblock polymers are preferred because they are industrially easily available.

  As such a styrenic thermoplastic elastomer, those obtained by block copolymerization of an aromatic vinyl compound and a conjugated diene compound by a known method such as anionic polymerization, cationic polymerization, coordination polymerization, radical polymerization and the like are employed without particular limitation. These production conditions are not particularly limited, but those produced by living radical polymerization are preferably used.

<High molecular compounds excluding styrene thermoplastic elastomer>
Moreover, the following are mentioned as a high molecular compound except a styrene-type thermoplastic elastomer.

  Specifically, polyaryl ether sulfone, polyether ether sulfone, polyether ketone, polyether ketone ketone, polysulfone, polyparaphenylene, polyphenylene sulfide, polyphenylene ether, polyphenylene sulfoxide, polyphenylene sulfide sulfone, polyphenylene sulfone, polybenzimidazole, Polybenzoxazole, polybenzothiazole, polystyrene, syndiotactic polystyrene, polyether sulfone, poly 1,4-biphenyl ether ether sulfone, polyarylene ether sulfone, polyimide, polyether imide, cyanate ester resin, polyether ether ketone, etc. Can be illustrated. Considering especially chemical and thermal stability, ease of introduction of proton conductive substituents, proton conductivity of the resulting proton conductive polymer electrolyte, polyether ether sulfone, polyether sulfone, polyphenylene ether Can be illustrated.

Moreover, one aspect of the polymer compound containing a proton conductive group, excluding the styrenic thermoplastic elastomer,
Component (A) in the resin composition for a binder characterized by containing a proton conductive group of the present invention (a polymer compound containing a proton conductive group and excluding a styrene-based thermoplastic elastomer),
An aromatic polymer compound containing a proton conductive group, and / or
It may be characterized by being an aliphatic polymer compound containing a proton conductive group.
The aliphatic polymer compound containing a proton conductive group may be a super strong acid group-containing fluorine polymer.
In the case of an aromatic polymer compound containing a proton conductive group and an aliphatic polymer compound containing a proton conductive group, a fat containing a proton conductive group in the component (A) The content of the group A hydrocarbon in the component (A) is preferably 10% by weight or more and 95% by weight or less.

The resin composition for a binder according to one aspect of the present invention,
(A) a polymer compound containing a proton conductive group, excluding a styrene-based thermoplastic elastomer,
(B) a styrenic thermoplastic elastomer containing a proton conductive group,
(C) a styrenic thermoplastic elastomer containing no proton conductive group,
The resin composition for a binder according to the first aspect of the present invention, characterized in that the resin composition comprises two or more selected from among the above and contains (C) as an essential component. is there.

Therefore,
(A) + (C),
Components other than (A) + (C) and (C),
(B) + (C),
Components other than (B) + (C) and (A),
(A) + (B) + (C),
Components other than (A) + (B) + (C) and (A) (B) (C),
There are cases.
Accordingly, the resin composition for a binder of the present invention includes (C) a thermoplastic styrenic thermoplastic elastomer that does not contain a proton conductive group. (C) provides at least adhesiveness. Of course, adhesiveness can also be obtained by (B).
Moreover, since the component (A) and / or the component (B) contains a proton conductive group, the proton conductive group is contained.
Therefore, the resin composition for a binder of the present invention obtained in this way is preferable because both functions of the thermoplastic elastomer and proton conductive group related to adhesiveness, that is, both adhesiveness and proton conductivity function.

  Solvents for dissolving the aromatic polymer compound containing a proton conductive group are N, N-dimethylformamide, 1-methyl-2-pyrrolidone, 2-propanol, chloroform, methylene chloride, 1,2-dichloroethane, cyclohexane, Hexane, ether, tetrahydrofuran, ethyl acetate and the like are exemplified, but not particularly limited. In particular, N, N-dimethylformamide and 1-methyl-2-pyrrolidone are preferred because of their high boiling point.

<Styrenic thermoplastic elastomer, monomer component forming the polymer main chain>
Moreover, it is preferable that the monomer component which has a styrene skeleton is 10 mol% or more and 70 mol% or less in the ratio of the monomer component which forms the polymer main chain of this styrene-based thermoplastic elastomer. This is because, in terms of the content of the rigid styrene skeleton, if it is less than 10 mol%, the thermal fusion temperature tends to be too low. When it exceeds 70 mol%, the heat sealing temperature tends to be excessively increased.

  Further, a chemical structural formula of a monomer component (other than styrene) having no styrene skeleton of the styrene-based thermoplastic elastomer is a group represented by the following general formula (1)

（Ｒ₁〜Ｒ₁₂は、Ｈ、低級アルキル、低級フルオロアルキルからなる群から選ばれ、Ｒ₁〜Ｒ₁₂は独立であって、互いに同一でも異なっていても良い、ｌ，ｍ，ｎは０以上である）であることは、好ましい。

(R _{1 to} R ₁₂ are selected from the group consisting of H, lower alkyl, and lower fluoroalkyl, and R _{1 to} R ₁₂ are independent and may be the same or different. L, m, and n are 0. That is the above.

  On the other hand, the styrenic elastomer may be a random polymer, a triblock polymer, or a diblock copolymer. Preferably, a triblock polymer is preferable from the viewpoint of adhesion and tackiness.

<High molecular compound containing proton conductive group>
The polymer compound containing a proton conductive group is
A polymer compound having a proton conductive group directly connected to the main chain skeleton of the polymer compound, and / or a polymer compound having a proton conductive group in the side chain of the main chain skeleton of the polymer compound;
As long as it is, it is not particularly limited.

(A) the high molecular compound excluding the styrenic thermoplastic elastomer containing the proton conductive group described above, and / or
(B) a styrenic thermoplastic elastomer containing a proton conductive group,
Is an embodiment of a polymer compound containing a proton conductive group.

<Polymer compound containing no proton conductive group>
The polymer compound containing no proton conductive group is
There is no particular limitation as long as the proton-conducting group is a polymer compound that does not contain the main chain skeleton or side chain of the polymer compound.

(C) the above-described styrene thermoplastic elastomer containing no proton conductive group,
Is an embodiment of a polymer compound not containing a proton conductive group.

<Membrane-electrode assembly, polymer electrolyte fuel cell, direct liquid fuel cell, direct methanol fuel cell>
As one aspect of the present invention,
The resin composition for a binder of the present invention is a binder / binder at the membrane-electrode interface of the membrane-electrode assembly, and / or
Binders and binders that bind the catalyst to the catalyst carrier,
As used.

  Further, according to one aspect of the present invention, a proton conductive polymer for a solid polymer fuel cell, a direct liquid fuel cell, and a direct methanol fuel cell is obtained by casting the resin composition for a binder of the present invention into a cast film. It is characterized by being used for a binder and a binder used in a membrane-electrode assembly which is a joined body of a membrane and a catalyst-carrying gas diffusion electrode.

  Further, according to one aspect of the present invention, a proton conductive polymer for a solid polymer fuel cell, a direct liquid fuel cell, and a direct methanol fuel cell is obtained by casting the resin composition for a binder of the present invention into a cast film. It is characterized by being used for a binder and a binder used in a membrane-electrode assembly which is a joined body of a membrane and a catalyst-carrying gas diffusion electrode.

One embodiment of the present invention includes
A 90 ° peel test was performed on the resin composition cast film formed from the binder according to the present invention and a hydrocarbon-based polymer electrolyte membrane, and the peel strength was measured. The result is a membrane-electrode assembly characterized by 2.0 N / cm.

  Next, a solid polymer fuel cell (direct methanol fuel cell) used for the proton conductive polymer membrane of the present invention will be described with reference to the drawings as an example.

  FIG. 1 is a cross-sectional view of an essential part of a solid polymer fuel cell (direct methanol fuel cell) using the proton conductive polymer membrane of the present invention.

  This is composed of a proton conducting polymer membrane 1, a catalyst-carrying gas diffusion electrode 2 in contact with one membrane, a fuel gas or liquid formed in the separator 4, and a flow path 3 for feeding an oxidant. Is.

  The method of joining the catalyst-carrying gas diffusion electrode 2 to the proton conducting polymer membrane 1 has been studied in the past. The proton conducting polymer membrane comprising a perfluorocarbon sulfonic acid membrane or the proton conducting polymer membrane comprising a polymer compound has been studied. Known methods performed with molecular membranes (for example, sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfonated polysulfone, sulfonated polyimide, sulfonated polyphenylene sulfide, etc.) are applicable.

  Specifically, a method using a commercially available gas diffusion electrode (manufactured by E-TEK, USA) can be exemplified, but the method is not limited thereto.

  As an actual method, an alcohol solution of a perfluorocarbon sulfonic acid polymer (such as a Nafion solution manufactured by Aldrich), a sulfonated polymer compound constituting the proton conductive polymer membrane of the present invention, or a known sulfonated polymer The proton conductive polymer membrane 1 of the present invention using an organic solvent solution of a compound (for example, sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfonated polysulfone, sulfonated polyimide, sulfonated polyphenylene sulfide, etc.) as a binder. The surface on the catalyst layer side of the catalyst-carrying gas diffusion electrode 2 is aligned with both surfaces of the metal and can be joined at a press temperature of about 120 to 250 ° C. using a press machine such as a hot press machine or a roll press machine. . Moreover, it is not necessary to use a binder as needed. Further, the catalyst-carrying gas diffusion electrode 2 may be prepared using the following materials and bonded to the proton conducting polymer membrane 1 for use.

  Here, the material used to prepare the catalyst-carrying gas diffusion electrode 2 includes, as a catalyst, a metal such as platinum or ruthenium or an alloy thereof that promotes a fuel oxidation reaction and oxygen reduction reaction, a catalyst carrier, Conductive materials such as fine-particle carbon materials (for example, carbon nanohorns, fullerenes, activated carbon, carbon nanotubes, etc.) as conductive materials, fluorine-containing resins having water repellency as binders, etc., if necessary Examples of the support include carbon cloth and carbon paper, and examples of the impregnation / coating material include perfluorocarbon sulfonic acid polymers, but the present invention is not limited thereto.

  A pair of graphite in which a flow path 3 for feeding a fuel gas or a liquid and an oxidant is formed on the assembly of the proton conductive polymer membrane 1 and the catalyst-carrying gas diffusion electrode 2 obtained by the above method. A solid polymer fuel cell (direct methanol fuel cell) comprising the proton conductive polymer membrane of the present invention can be obtained by inserting it between gas separators 4 such as manufactured products. A gas containing hydrogen as a main component, a gas or liquid containing methanol as a main component as a fuel gas or liquid, and a gas containing oxygen (oxygen or air) as an oxidant are supplied from separate flow paths 3 respectively. By supplying the catalyst-supported gas diffusion electrode 2, the polymer electrolyte fuel cell operates. At this time, when methanol is used as the fuel, a direct methanol fuel cell is obtained.

  The polymer electrolyte fuel cell of the present invention can be used alone or in a stack to form a stack, or a fuel cell system incorporating them can be used.

  Furthermore, as an example of a direct methanol fuel cell using a proton conductive polymer membrane as an example including a membrane-electrode assembly that includes the binding resin composition of the present invention, the drawings are cited as an example. explain.

  FIG. 2 is a cross-sectional view of the main part of a direct methanol fuel cell comprising the proton conducting polymer membrane of the present invention. The proton conducting polymer membrane 5 and the catalyst-supporting electrode 6 are joined to both sides of the membrane 5 to form a membrane-electrode assembly. The required number of membrane-electrode assemblies are arranged in a plane on both sides of a fuel (methanol or methanol aqueous solution) tank 7 having a fuel (methanol or methanol aqueous solution) filling section 8 and a supply section 8. Further, a support body 9 in which an oxidant flow path 10 is formed is arranged on the outer side, and a cell and a stack of a direct methanol fuel cell are configured by being sandwiched between them.

Besides the above example,
A membrane-electrode assembly including the binding resin composition of the present invention,
Proton conducting polymer membrane
JP 2001-313046, JP 2001-313047, JP 2001-93551, JP 2001-93558, JP 2001-93561, JP 2001-102669, JP 2001-102070, JP-A-2001-283888, JP-A-2000-268835, JP-A-2000-268836, JP-A-2001-283892, etc. A membrane-electrode assembly containing a binding resin composition,
It can be used as a proton conductive polymer electrolyte membrane.

  The binder used for the polymer electrolyte membrane-electrode assembly containing a proton conductive group in the solid polymer fuel cell, direct liquid fuel cell, and direct methanol fuel cell according to the present invention is the resin composition described above. The binder resin composition containing the product is included.

  Moreover, it can also be used in combination with other various ion conductive polymers. Examples of other various ion conductive polymers include polymers obtained by adding a proton conductive group to a fluorine polymer, a polyolefin polymer, or the like. Examples of proton conductive groups include sulfonic acid groups, phosphoric acid groups, carboxylic acid groups, phenolic hydroxyl groups, sulfonimide groups, and the like. Of these, Nafion (registered trademark) manufactured by DuPont may be used as a blend component as an embodiment. Further, an inorganic ion conductive material such as silica may be used.

<Ion exchange capacity>
The ion exchange capacity of the resin composition for a binder having a proton conductive group of the present invention is preferably 1.0 meq / g or more. More preferably, it is 1.2 meq / g or more. When it is 1.0 meq / g or more, in addition to the function used for binding the catalyst to the catalyst support, the proton conductivity is sufficiently exhibited, which is preferable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these Examples, In the range which does not change the summary, it can change suitably.

(Ion exchange capacity of proton conductive polymer electrolyte membrane and single layer membrane of binding resin composition containing proton conductive group of the present invention: IEC measurement method)
A proton conductive polymer electrolyte membrane of about 10 mm × 40 mm and a single layer membrane of a binding resin composition containing a proton conductive group of the present invention are each immersed in 20 mL of a saturated aqueous sodium chloride solution at 25 ° C. The reaction was carried out in a 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 recovered solution, a phenolphthalein solution was added as an indicator, and neutralization titration with a 0.01N sodium hydroxide aqueous solution was performed to calculate the ion exchange capacity.

(Proton conductivity (membrane direction) of proton conducting polymer electrolyte membrane: σ measurement method)
The proton conductive polymer electrolyte membrane was cut into a circular shape with a diameter of 16 mm, and excess moisture was wiped off with a filter paper before being used for measurement. After attaching stainless steel electrodes to the front and back surfaces of the test specimen and installing them in a bipolar metal cell, the AC impedance method (frequency: 42 Hz to 5 MHz, manufactured by Hioki Denki Co., Ltd.) under the condition of a voltage of 0.5 V at room temperature. Membrane resistance was measured with an LCR meter (3531Z HITESTER), and the proton conductivity in the membrane direction was calculated.

(Measurement method of 90 degree peeling peel strength of proton conductive polymer electrolyte membrane and proton conductivity imparting agent cast film)
Measurement was performed at a line width of 1.25 mm according to the JIS C6481 method using a strograph VES1D manufactured by Toyo Seiki.

(Synthesis Example 1)
(Synthesis of Aromatic Hydrocarbon Proton Conducting Polymer Compound: s-PEEK)
In a reaction vessel equipped with a mechanical stirrer, a nitrogen introduction tube, and a dropping funnel, 3.7 g of PEEK 450P (manufactured by Victorex MC Ltd., molecular weight of about 100,000) was put. In the reactor, 92 g of concentrated sulfuric acid was added from a dropping funnel and stirred at room temperature for 3 days. After completion of the reaction, the reaction solution was poured into 3 liters of pure water and washed with 3 liters of water 10 times until the filtrate became neutral with water. The obtained product was dried at 90 ° C. under a vacuum of 1 Torr for 10 hours to obtain 4.5 g of a yellow solid. In the obtained solid, sulfonic acid groups were observed at 1450, 1445, and 1390 cm ⁻¹ of the infrared spectrum of the obtained solid. Ion exchange capacity: IEC was calculated to be 2.17 meq / g. A solution prepared from 2.14 g of this resin and 26.4 g of DMF was placed in a petri dish having an inner diameter of 60 mm and dried in a vacuum oven at 110 ° C. for 3 hours under 1 Torr. The resulting dried film was swollen with water, peeled off from the petri dish, and dried at 1 Torr, 110 ° C. for 5 hours. A blend resin composition film having a thickness of 30 μm was obtained. Its proton conductivity: σ was 7.5 × 10 ⁻² S / cm.

(Synthesis Example 2)
(Aromatic hydrocarbon proton conductive polymer compound: synthesis of s-PES)
15.0 g of PES7600P (manufactured by Sumitomo Chemical Co., Ltd., molecular weight of about 150,000) was put in a reaction vessel equipped with a mechanical stirrer, a nitrogen introduction tube, and a dropping funnel. In the reactor, 138 g of concentrated sulfuric acid was added from the dropping funnel and stirred at room temperature for 1 day. To this reaction solution, 50.5 g of chlorosulfonic acid was added dropwise under nitrogen, followed by stirring at room temperature for 3 hours. After completion of the reaction, the reaction solution was poured into 3 liters of pure water and washed with 3 liters of water 20 times until the filtrate became neutral with water. The obtained product was dried at 90 ° C. under a vacuum of 1 Torr for 10 hours to obtain 16.0 g of a white solid. Sulfonic acid groups were observed at 1450, 1445, and 1390 cm ⁻¹ in the infrared spectrum. The ion exchange capacity was 1.39 meq / g, and the proton conductivity of the adjusted resin membrane (30 μm) was 4.2 × 10 ⁻² S / cm.

(Synthesis Example 3)
(Proton conductive styrene elastomer: synthesis example of s-SEPS)
In a reaction vessel equipped with a mechanical stirrer, a nitrogen introduction tube and a dropping funnel, 5.0 g of Septon SEPS2007 (manufactured by Kuraray Co., Ltd., molecular weight of about 80,000), 15 g of 1,2-dichloroethane, and 25 g of cyclohexane were added at room temperature. Stir for hours. In the reactor, 0.66 g of chlorosulfonic acid dissolved in 10 g of dichloroethane was added from a dropping funnel and stirred at room temperature for 2 hours. After completion of the reaction, the reaction mixture was poured into 1 liter of methanol, washed 3 times, and washed twice with 1 liter of water until the filtrate became neutral with water. The obtained product was dried at 90 ° C. under a vacuum of 1 Torr for 10 hours to obtain 6.0 g of a brown solid. Sulfonic acid groups were observed at 1450, 1445, and 1390 cm ⁻¹ in the infrared spectrum. The ion exchange capacity was 1.22 meq / g, and the proton conductivity of the prepared resin membrane (30 μm) was 1.1 × 10 ⁻² S / cm.

(Synthesis Example 4)
(Proton conductive styrene elastomer: synthesis example of s-SEBS)
When Septon SEPS2007 was replaced with 5 g of SEBS G1650 (manufactured by Kraton, molecular weight of about 70,000) in the same manner as in Synthesis Example 3, 6.0 g of product was obtained. In the obtained solid, sulfonic acid groups were observed at 1450, 1445, and 1390 cm ⁻¹ of the infrared spectrum of the obtained solid. The ion exchange capacity was 1.34 meq / g, and the proton conductivity of the adjusted resin membrane (30 μm) was 3.1 × 10 ⁻² S / cm.

(Synthesis Example 5)
(Proton conductive styrene elastomer: synthesis example of s-SIBS)
When Septon SEPS3007 was replaced with 5.0 g of SIBS 103T022 (manufactured by Kaneka Co., Ltd., molecular weight of about 50,000), the same procedure as in Synthesis Example 3 was carried out to obtain 6.0 g of product. In the obtained solid, sulfonic acid groups were observed at 1450, 1445, and 1390 cm ⁻¹ of the infrared spectrum of the obtained solid. The ion exchange capacity was 0.76 meq / g. The ion exchange capacity was 1.32 meq / g, and the proton conductivity of the adjusted resin membrane (30 μm) was 2.7 × 10 ⁻² S / cm.

Example 1
(Single layer film of resin composition for binder of the present invention)
To the reaction vessel 1, 0.4 g of s-PEEK obtained in Synthesis Example 1 and 10 g of DMF were added and stirred. In another container 2, 0.15 g of styrene thermoplastic elastomer not containing a proton conductive group: SEPS2007 (manufactured by Kuraray Co., Ltd., molecular weight of about 80,000) and 2 g of cyclohexane were added and stirred. The solution in the reaction vessel 1 was transferred to the reaction vessel 2 and further stirred for 30 minutes. Each 1.64 g was placed in a petri dish having an inner diameter of 60 mm and dried at 90 ° C. for 10 hours under a vacuum of 1 Torr. When this was swollen with water, peeled off from the petri dish, and dried at 110 ° C. for 5 hours under a vacuum of 1 Torr, a 40 μm cast film was obtained. The ion exchange capacity was 1.27 meq / g, and the proton conductivity of the adjusted blend resin membrane (single layer membrane of the resin composition for a binder of the present invention) was 5.4 × 10 ⁻² S / cm.

(Polymer electrolyte membrane corresponding to the membrane-electrode assembly membrane)
A sulfonic acid-modified PPS containing a proton conductive group (PPS: Torelina manufactured by Toray Industries, Inc., 25 μm) prepared according to the method described in JP-T-11-510198 was cut into a 5 cm square.

(Lamination test of laminate)
above,
A single layer film of the resin composition for a binder of the present invention;
A polymer electrolyte membrane corresponding to a membrane-electrode assembly membrane,
After lamination
Using a FUJIKIKO KFS37 press machine manufactured by Fuji Kiko Co., Ltd., press working was performed at 150 ° C. and 7.0 N / cm ² for 3 minutes. The resulting laminated film (65 μm) had a 90-degree peel peel strength of 6.5 N / cm, and a 90-degree peel peel strength after immersion in pure water at 23 ° C. for 24 hours was 6.0 N / cm. The results are summarized in Table 1.

なお、表中の略号は、以下の内容を示し、以下の実施例２〜１７、比較例１，２でも同様である。
・ＰＥＥＫ：４５０Ｐ（ビクトレックスエムシー社製、分子量：約１０万）、
・ＰＥＳ：７６００Ｐ（住友化学社製、分子量：約７万）、
・ＳＥＰＳ：ＳＥＰＴＯＮ２００７（クラレ社製、分子量：約７万）、
・ＳＥＢＳ：Ｇ１６５０（Ｋｒａｔｏｎ社製、分子量：約７万）、
・ＳＩＢＳ：１０３Ｔ０２２（（株）カネカ製、分子量：約５万）、
・ＳＩＳ：ＳＩＳ５００２（ＪＳＲ社製、分子量：約５万）、
・ＳＢＳ：Ｄ−ＫＸ４０１ｃｓ（Ｋｒａｔｏｎ社製、分子量：約６万）、
・Ｎａｆｉｏｎ：ナフィオン（登録商標）５ｗｔ％イソプロパノール−水分散液（アルドリッチ社製）
（実施例２〜１７、比較例１、２）
表1に示した組成に記載に変えた以外は実施例１と同様にして、評価を行った。その結果を表１に示した。

The abbreviations in the table indicate the following contents, and the same applies to Examples 2 to 17 and Comparative Examples 1 and 2 below.
PEEK: 450P (manufactured by Victrex MC, molecular weight: about 100,000),
-PES: 7600P (Sumitomo Chemical Co., Ltd., molecular weight: about 70,000),
・ SEPS: SEPTON 2007 (manufactured by Kuraray Co., Ltd., molecular weight: about 70,000),
SEBS: G1650 (manufactured by Kraton, molecular weight: about 70,000),
SIBS: 103T022 (manufactured by Kaneka Corporation, molecular weight: about 50,000),
SIS: SIS5002 (manufactured by JSR, molecular weight: about 50,000),
SBS: D-KX401cs (manufactured by Kraton, molecular weight: about 60,000),
Nafion: Nafion (registered trademark) 5 wt% isopropanol-water dispersion (manufactured by Aldrich)
(Examples 2 to 17, Comparative Examples 1 and 2)
Evaluation was performed in the same manner as in Example 1 except that the composition shown in Table 1 was changed. The results are shown in Table 1.

It is principal part sectional drawing of the polymer electrolyte fuel cell (direct methanol fuel cell) of this invention. It is principal part sectional drawing of the direct methanol type fuel cell of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Proton conductive polymer membrane 2 Catalyst carrying | support gas diffusion electrode 3 Channel 4 Separator 5 Proton conductive polymer membrane 6 Catalyst carrying gas diffusion electrode 7 Fuel tank 8 Fuel filling part 9 Support body 10 Oxidant flow channel

Claims (12)

  A resin composition for a binder used for a polymer electrolyte membrane-electrode assembly containing a proton conductive group of a solid polymer fuel cell, a direct liquid fuel cell, and a direct methanol fuel cell, A resin composition for a binder, wherein the binder resin composition comprises a polymer compound containing a proton conductive group and a polymer compound not containing a proton conductive group. The binder resin composition is
(A) a polymer compound containing a proton conductive group, excluding a styrene-based thermoplastic elastomer,
(B) a styrenic thermoplastic elastomer containing a proton conductive group,
(C) a styrenic thermoplastic elastomer containing no proton conductive group,
2. The resin composition for a binder according to claim 1, which is a resin composition containing two or more selected from the above and containing (C) as an essential component.   The ratio of the monomer component forming the polymer main chain of the styrenic thermoplastic elastomer is 10 mol% or more and 70 mol% or less of the monomer component having a styrene skeleton. The resin composition for a binder according to any one of 2 above. The chemical structural formula of the monomer component having no styrene skeleton of the styrene elastomer is a group represented by the following general formula (1)

(R _{1 to} R ₁₂ are selected from the group consisting of H, lower alkyl, and lower fluoroalkyl, and R _{1 to} R ₁₂ are independent and may be the same or different. L, m, and n are 0. The resin composition for a binder according to any one of claims 1 to 3, wherein   The resin composition for a binder according to any one of claims 1 to 4, wherein the ion exchange capacity of the resin composition for a binder is 1.0 meq / g or more.   The resin composition for a binder according to any one of claims 1 to 5, wherein the proton conductive group contains a sulfonic acid group.   Furthermore, the super strong acid group containing fluorine polymer is added, The resin composition for binders in any one of Claims 1-6 characterized by the above-mentioned.   The resin composition for a binder according to claim 7, wherein the super strong acid group-containing fluorine-based polymer is Nafion (registered trademark).   The resin composition for a binder according to any one of claims 1 to 8, wherein the polymer electrolyte membrane containing a proton conductive group contains polyphenylene sulfide (PPS).   A polymer electrolyte membrane comprising the binder resin composition according to claim 1.   A polymer electrolyte membrane-electrode composite comprising the binder resin composition according to claim 1.   A solid polymer fuel cell, a direct liquid fuel cell, or a direct methanol fuel cell, comprising the binder resin composition according to claim 1.

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