JP2003285396A - Base material film for producing electrode film and/or electrolyte film and method for producing joined body of electrode film and electrolyte film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base material film developing no wrinkles or shrinkage, improved in the peelability from an electrode film, not staining the electrode film and/or an electrolyte film and used at the time of production the electrode film and/or the electrolyte film for a solid polymer type fuel cell and the joined body of the electrode film and the electrolyte film. <P>SOLUTION: The base material film has the electrode film and/or the electrolyte film comprising at least a solid polymeric electrolyte formed on the surface thereof and is constituted by laminating a support film and a film having releasability formed on at least the single surface thereof. Further, this base material film is used for producing the electrode film and/or the electrolyte film and the joined body of both films. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode membrane and / or an electrolyte membrane preferably used as a member for a polymer electrolyte fuel cell, and a base film for producing a joined body thereof, and particularly to wrinkles and wrinkles. A base film for producing an electrode membrane and / or an electrolyte membrane, which does not exhibit shrinkage, has good peelability from the electrode catalyst layer, and does not contaminate the electrode catalyst and the electrolyte membrane, and a bonded body of the electrode membrane and the electrolyte membrane Manufacturing method.

[0002]

2. Description of the Related Art A fuel cell directly converts chemical energy of a fuel into electric energy by electrochemically oxidizing hydrogen, methanol, etc. in the cell and takes out a clean electric energy in recent years. Attracted as a source. Particularly, the polymer electrolyte fuel cell is easy to miniaturize and operates at a relatively low temperature, and thus is expected as an alternative power source or a dispersed power source for automobiles. Such a polymer electrolyte fuel cell has a structure in which a positive electrode (anode) and a negative electrode (cathode) are provided on both sides of a polymer electrolyte membrane. Is provided with an anode catalyst layer, the other surface is provided with a cathode catalyst layer, and a pair of gas diffusion electrodes are provided adjacent to each other on the outer sides of both surfaces.

In the polymer electrolyte fuel cell, further improvement in energy efficiency is required. For that purpose, the electrode structure is devised to increase the reaction active points of the electrode reaction, and
The solid polymer electrolyte membrane is also placed inside the electrode membrane so that hydrogen ions can move quickly. In order to quickly move the generated hydrogen ions to the counter electrode, it is necessary to make good contact between the electrode membrane and the polymer electrolyte membrane that is the diaphragm, and to lower the membrane resistance of the polymer electrolyte membrane itself. For that purpose, it is preferable that the film thickness is as thin as possible. In addition, the polymer electrolyte membrane used must be used in a wet state at all times, because the hydrogen ion conductivity will decrease and polarization will occur, resulting in poor performance. However, the thinner the polymer electrolyte membrane is, the better the humidification efficiency is, and it can be expected that the limiting current density is improved.

Therefore, a solution of electrode catalyst particles (active catalyst metal particles such as platinum or platinum alloy, or a catalyst carrier such as carbon black supporting the active catalyst metal particles) and a solid polymer electrolyte resin or a precursor thereof. Substance resin solution mixed or PTFE (polytetrafluoroethylene)
A paste-like or ink-like liquid in which a particle dispersion liquid (dispersion) and electrode catalyst particles are mixed is applied onto a substrate film, heated and dried, and then a solid polymer electrolyte resin solution is applied and dried thereon. Thus, the solid polymer electrolyte membrane is directly formed into a joined body, and the joined bodies thus formed are then brought into contact with each other and hot-pressed to form an anode / membrane / cathode integrated molded product. A method of peeling the material film, or a material obtained by applying and drying the above paste-like or ink-like liquid on a substrate film is sandwiched on both sides of a solid polymer electrolyte membrane formed in advance, and hot pressed to form an anode. There has been proposed a method of peeling the base material film after forming the film / membrane / cathode integrated molded product.

[0005]

The substrate film used in the above method includes (1) a polyester film having a surface coated with a silicone resin (hereinafter referred to as "silicone-coated PET"), and (2) a stretched film. A polypropylene single film (hereinafter referred to as "OPP") or (3) a single fluorine-based film (hereinafter referred to as "fluorine-based film") composed of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, etc. is usually used. Has been done. However, these films have the following problems. (1) Silicone-coated PET: Poor peelability from the electrode catalyst layer results in poor productivity, and further, the electrode catalyst and electrolyte membrane are contaminated with silicone, and hydrogen ion conductivity tends to decrease. (2) OPP: The film shrinks when the solution of the solid polymer electrolyte resin is removed by drying. (3) Fluorine-based film: Since it is soft and easily stretched, wrinkles are formed in the film and workability is poor.

[0006]

The present invention solves the above-mentioned problems.
We have found a base film that can be eliminated, and
The place to do is to use at least a solid polymer electrolyte.
Base film having a polar membrane and / or an electrolyte membrane formed on the surface
In, the base film and the support film and at least one piece
It has a special feature that a film with releasability is laminated on the surface.
Substrate fill for manufacturing electrode film and / or electrolyte film to be measured
It is in Mu. The above laminated film includes a support film and
Even if there is no release film on one side,
The film having releasability is a fluororesin,
Including that the thickness is in the range of 1 to 50 μm.
The support film in RUM is measured according to ASTM D882.
Specified tensile elastic modulus is 980-6,860 N / mm ^Twoso
The melting point is 150 ° C or higher, and the thickness is 5
Including the range of 500 μm
It includes that the thickness is in the range of 6 to 600 μm.
In addition, at least one side of the support film has releasability.
The releasability of the base film on which the film
On the surface of the film, at least the electrode catalyst particles and the solid
Membrane-base material on which electrode membrane composed of solid polymer electrolyte is formed
A film composite is obtained, and a solid film is formed on the electrode film.
Solid polymer electrolyte membrane-electrode membrane-base material that forms a child electrolyte membrane
After obtaining the film composite, two sets of the solid polymer electrolyte
Membrane-electrode membrane-base film composite, each supporting film
Place it on the outside, and hot-press the electrode film and electrolyze it.
To obtain a bonded body of the quality membrane and to release the base film
On the surface of the film, at least the electrode catalyst particles and the solid
Membrane-base film composite consisting of polymer electrolyte
After being obtained, the above-mentioned electrode film-substrate substrate with the support film on the outside
A solid polymer electrolyte formed in advance between two film composites.
Electrolyte membrane and electrolyte membrane by hot pressing with sandwiching electrolyte membrane
Including the manufacturing method of obtaining the joined body of
I'm out.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The substrate film of the present invention needs to have a structure in which a film having releasability is laminated on at least one surface of the support film, and by having such a structure,
When forming the electrode film and / or the electrolyte film on the surface of the base material film, wrinkles and shrinkage are not particularly expressed, and the peeling (release) from the electrode film and the like is good, and further contamination of the electrode film and the electrolyte film is prevented. It can be lost.

As the resin for the film having releasability, PTFE (polytetrafluoroethylene), PF
A (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), EPE
(Tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer), E
TFE (tetrafluoroethylene-ethylene copolymer), PCTFE (polychlorotrifluoroethylene), ECTFE (chlorotrifluoroethylene-ethylene copolymer), PVDF (polyvinylidene fluoride),
PVF (polyvinyl fluoride), THV (tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer), VDF-HFP (vinylidene fluoride-hexafluoropropylene copolymer), TFE-P
At least one kind of fluororesin selected from (vinylidene fluoride-propylene copolymer) can be used.

Of the above-exemplified resins, FEP and ETFE are particularly preferable from the viewpoint of moldability and releasability.

The thickness of the release film is 1 to 50 μm.
The range of m is preferable, and when it is less than 1 μm, perforation occurs during film formation, and even if it is laminated with a support film, the releasability of that portion cannot be obtained. The cost is also high.

In the laminated film of the present invention, various known films can be used as the support film. Examples of the film include polyester, polycarbonate, triacetyl cellulose, cellophane, polyamide, aromatic polyamide, polyimide, polyetherimide, polyphenylene sulfide, polysulfone, polyether sulfone, and polypropylene. Among them, the polyester film is preferable in terms of heat resistance, mechanical properties and the like.

The supporting film is ASTM D88.
The tensile elastic modulus measured according to 2 is 980 to 6,860 N
/ Mm ² , preferably 2,940 to 5,880 N / mm
² and the tensile elastic modulus is less than 980 N / mm ² ,
There are problems that the film is soft and is not easy to handle, and that wrinkles easily occur. Also, the tensile elastic modulus is 6,
When it exceeds 860 N / mm ² , there is a problem that it is too hard as a support film, and it is difficult to handle and the workability is poor.

The melting point of the supporting film is 150 ° C.
If the melting point is less than 150 ° C., the drying temperature of the electrolyte membrane solution cannot be increased, so that the drying time is long and the productivity is poor.

The thickness of the support film is 5 to 5
00 μm, preferably in the range of 10 to 300 μm,
If it is less than 5 μm, sufficient strength as a supporting film cannot be obtained and wrinkles are likely to be formed, and if it exceeds 500 μm, the stiffness becomes too strong and it is difficult to handle and the workability is poor.

The total thickness of the laminated film is in the range of 6 to 600 μm. If it is less than 6 μm, the thickness is too thin and wrinkles easily occur. If it exceeds 600 μm, the thickness accuracy becomes poor and the material cost becomes high. Is too strong, which makes it difficult to handle and poor in workability.

The method of laminating the film having releasability and the support film is not particularly limited, but a dry laminating method and an extrusion laminating method are preferable. Compared to the case where a support film is coated with a resin having releasability, the resin component having releasability does not migrate to the electrode catalyst and the electrolyte membrane, so that the conductivity of hydrogen ions does not decrease due to contamination or the like. . Examples of the adhesive used at that time include acrylic, isocyanate, polyethyleneimine, polyurethane, and silane coupling agent. Among them, a polyurethane-based laminating adhesive can be preferably used. Further, as a pretreatment for laminating, it is preferable to perform corona treatment on the laminated adhesive surface of the support film and the release film.

Although the electrode film and / or the electrolyte membrane and the bonded body are manufactured using the substrate film having the above-mentioned contents, there are various manufacturing methods and the manufacturing method is not limited. For example,
As a method for producing a joined body, at least one of electrode catalyst particles and a solid polymer electrolyte is formed on a releasable film surface of a base film in which a releasable film is laminated on at least one surface of a support film. After obtaining an electrode membrane-base film composite having an electrode membrane formed thereon, a solid polymer electrolyte membrane is further formed on the electrode membrane to obtain a solid polymer electrolyte membrane-electrode membrane-base film composite, Two sets of the solid polymer electrolyte membrane-electrode membrane-base film composite are
Each supporting film is placed on the outside, a method for obtaining a bonded body of an electrode membrane and an electrolyte membrane by hot pressing, and a method of peeling the base film,

A base film in which a film having releasability is laminated on at least one surface of a support film. An electrode film-base material comprising at least electrode catalyst particles and a solid polymer electrolyte on the releasable film surface of the film. After obtaining the film composite, a solid polymer electrolyte membrane formed in advance is sandwiched between two sheets of the above-mentioned electrode membrane-base film composite having a support film on the outside, and the electrode membrane and the electrolyte are hot-pressed. There is a method of obtaining a membrane bonded body and peeling the base film.

Examples will be described below, but the present invention is not limited thereto.

[Examples] [Example 1] The following four types of base films were prepared. Base film 1 (Comparative Example 1): OPP (manufactured by Nimura Chemical Co., Ltd., thickness: 50 μm) Base film 2 (Comparative Example 2): Silicone-coated PET
(Mitsubishi Kagaku Polyester Co., Ltd., thickness 38 μm) Base film 3 (Comparative Example 3): ETFE (ethylene-tetrafluoroethylene copolymer) film (Asahi Glass Co., Ltd., thickness 25 μm) Base film 4 (implementation Example): ETFE (ethylene-tetrafluoroethylene copolymer, manufactured by Asahi Glass Co., Ltd.) was formed into a film of 5 μm by extrusion molding, and a polyethylene terephthalate film (manufactured by Mitsubishi Kagaku Polyester Co., Ltd., thickness 25) was used.
(μm) dry laminated film.

Next, 40% by weight of platinum catalyst-supporting carbon (manufactured by E-TEK, USA) and 5% by weight of electrolyte membrane solution (manufactured by Aldrich Chemical Co.) were added at a weight ratio of 2: 1 and uniformly added. A dispersed paste was prepared.

Next, the base film is set on a coating stand, the paste is applied onto the base film using a 300-mesh stainless screen, and then dried in an oven at 130 ° C. for 4 minutes. The material film was peeled off to obtain an electrode film having a platinum loading of 0.1 mg / cm ² . The handling properties when set on the coat stand, the presence or absence of shrinkage of the base film after drying the coating film, and the releasability of the coating film were determined according to the following criteria, and the results are shown in Table 1.

A. Handleability: When the base film was set on the coat base, it was easy to set without wrinkles, and when it was difficult to handle, x was set. B. Presence or absence of film shrinkage After drying the coating film, the substrate film that could be dried without shrinkage is ○, the film shrinks and wrinkles appear in the coating film.
Or, if the base film has peeled from the coating,
And C. Releasability of coating film: A film which can be easily peeled off from the base film was evaluated as ◯, and a film which was difficult to be peeled off due to the damage of the coating film was evaluated as x.

[0023]

[Table 1]

As shown in Table 1, the base film 4 formed by extruding ETFE to a thickness of 5 μm and dry-laminated on the PET film may have wrinkles as compared with the base films 1, 2 and 3. It has good handling properties, does not exhibit shrinkage during drying, has good mold releasability, and is excellent as a base film used in the production of electrode membranes and electrolyte membranes for fuel cells. I understand.

Example 2 The same manner as in Example 1 was applied to the substrate film 4 (a laminated film obtained by extrusion-molding ETFE into a film having a thickness of 5 μm and dry-laminating it onto a polyethylene terephthalate film having a thickness of 25 μm) used in Example 1 described above. The paste prepared in 1 above (40% by weight of platinum catalyst-supporting carbon and 5% by weight of electrolyte membrane solution were mixed at a weight ratio of 2: 1) was applied onto a base film using a 300 mesh stainless screen. , Then in the oven 13
It was dried at 0 ° C. for 4 minutes. Furthermore, the process of “coating only 5 wt% electrolyte membrane solution (manufactured by Aldrich Chemical Co.) using the same screen and drying in an oven at 100 ° C. for 10 minutes” was repeated 3 times to obtain a solid polymer electrolyte membrane- A cathode electrode film-base film composite was obtained. The thickness of the obtained solid polymer electrolyte membrane-cathode electrode membrane was 5 μm.

Further, a solid polymer electrolyte membrane-anode electrode membrane-base film composite was obtained by the same procedure as above. The solid polymer electrolyte membrane-cathode electrode membrane-base film composite and the solid polymer electrolyte membrane-anode electrode membrane-base film composite are placed such that the support film in the base film is on the outside. , 150 ° C, 3.5 × 10 ⁶ P
It was hot-pressed with a (36 kgf / cm ² ), and then the substrate film was peeled off to obtain a joined body of the electrode membrane and the electrolyte membrane.

Example 3 The substrate film 4 used in Example 1 was coated with the paste prepared in Example 1 on a substrate film using a 300-mesh stainless screen. Then in the oven 130
C., and dried for 4 minutes to obtain a cathode electrode film-base film composite. The thickness of the obtained electrode film was 1 μm. Further, an anode electrode film-base film composite was obtained by the same procedure as above. Each of the cathode electrode membrane-base film composite and the anode electrode membrane-base film composite is a solid polymer electrolyte membrane (thickness produced by DuPont Co., Ltd.) which is formed in advance with the support film in the base film being outside. 150 μm)
And place it at 150 ° C and 3.5 × 10 ⁶ Pa (3
Hot pressing was performed at 6 kgf / cm ² ) and then the substrate film was peeled off to obtain a joined body of the electrode membrane and the electrolyte membrane.

The base film 4 used in Examples 2 and 3 did not exhibit wrinkles or shrinkage, and had good releasability between the electrode membrane and the electrolyte membrane assembly. In addition, the obtained electrode membrane-electrolyte membrane assembly has good humidification efficiency,
The limiting current density was also high, and there was no problem in performance as a fuel cell.

[0029]

As described above, the releasable laminated film of the present invention does not exhibit wrinkles or shrinkage during the production of the electrode film and / or the electrolyte film and the assembly of the electrode film and the electrolyte film. Also, it has a good peeling property from the electrode membrane and does not contaminate the electrode membrane and / or the electrolyte membrane. Therefore, a base material used in the production of the electrode membrane and / or the electrolyte membrane for the polymer electrolyte fuel cell and the bonded body. It is highly usable as a film.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 8/10 H01M 8/10 F term (reference) 4F100 AK01A AK01E AK07 AK17 AK17C AK17D AK42 AL01 AR00C AR00D AT00B BA03 BA04 BA05 BA07 BA10A BA10B BA10C DE01E EJ202 EJ422 EJ912 GB41 JA04B JG10A JG10E JK07B JL08E JL14 JL14C JL14D YY00B YY00C YY00D 4J002 AA01 5H026 AA06 CX04 HH03 HH08 HH09

Claims (9)

[Claims] 1. A base film having an electrode film and / or an electrolyte film made of at least a solid polymer electrolyte formed on a surface thereof, wherein the base film is a support film and a film having releasability is laminated on at least one surface thereof. A substrate film for producing an electrode membrane and / or an electrolyte membrane, which is characterized in that 2. The base film for producing an electrode film and / or an electrolyte film according to claim 1, wherein the film having releasability is made of a fluororesin. 3. The thickness of the film having releasability is 1
The base film for producing an electrode film and / or an electrolyte film according to claim 1 or 2, wherein the film thickness is in the range of 50 to 50 μm. 4. The tensile elastic modulus (AS) of the support film.
(Measured according to TM D882) is 980 to 6,860
It is N / mm < ² >, The base film for manufacturing the electrode membrane and / or electrolyte membrane of any one of Claim 1 thru | or 3 characterized by the above-mentioned. 5. The base film for producing an electrode membrane and / or an electrolyte membrane according to claim 1, wherein the supporting film has a melting point of 150 ° C. or higher. 6. The support film has a thickness of 5 to 500 μm.
The substrate film for producing an electrode film and / or an electrolyte film according to any one of claims 1 to 5, wherein the base film is in the range of m. 7. The total thickness of the laminated film is 6 to 600.
The base film for producing an electrode membrane and / or an electrolyte membrane according to any one of claims 1 to 6, which is in a range of μm. 8. An electrode film comprising at least electrode catalyst particles and a solid polymer electrolyte is formed on the releasable film surface of a substrate film in which a releasable film is laminated on at least one surface of a support film. Formed electrode film-
A substrate film composite is obtained, and a solid polymer electrolyte membrane is further formed on the electrode membrane to form a solid polymer electrolyte membrane-electrode membrane-
After obtaining the base film composite, two sets of the solid polymer electrolyte membrane-electrode film-base film composite are placed with the support films on the outside, and hot pressing is performed to separate the electrode film and the electrolyte film. A method for producing a joined body of an electrode membrane and an electrolyte membrane, which comprises obtaining a joined body and peeling a base material film. 9. An electrode film comprising at least electrode catalyst particles and a solid polymer electrolyte on the releasable film surface of a substrate film in which a releasable film is laminated on at least one surface of a support film. After obtaining the base film composite, the solid polymer electrolyte membrane formed in advance is sandwiched between the two electrode film-base film composites with the support film on the outside, and the electrode film is hot pressed. A method for producing a joined body of an electrode membrane and an electrolyte membrane, comprising: obtaining a joined body of an electrolyte membrane and a base material film;