JP5369416B2 - Catalyst layer transfer film - Google Patents

Description

  The present invention relates to a catalyst layer transfer film.

  Various methods have been proposed to date for producing catalyst layers for fuel cells and the like. Among these, the transfer method of transferring the catalyst layer once produced using another base material to the electrolyte membrane is easy to form the catalyst layer, and since there is little adverse effect on the electrolyte membrane and the gas diffusion layer, It is advantageous.

  Examples of the base film used in the transfer method include (1) polyester film coated with a silicone resin on the surface, (2) stretched polypropylene film, (3) polytetrafluoroethylene, tetrafluoroethylene-hexa Fluorine-based films such as fluoropropylene copolymers are known. However, these substrate films have various problems. That is, in the base film of (1), it is inevitable that the electrode catalyst and the electrolyte membrane are contaminated by the silicone resin and the conductivity of hydrogen ions is lowered. The base film of (2) has a drawback that the film shrinks due to heat when the catalyst layer forming paste is applied on the film and dried to form the catalyst layer. The base film of (3) has the disadvantage that the film itself is soft and easily stretched, so that the film is wrinkled and inferior in workability.

  In order to solve such problems, a transfer film in which polyethylene terephthalate is used as a base film and a fluorine-based release component is laminated between the base film and the catalyst layer has been proposed (patent) Reference 1).

  When the transfer film described in Patent Document 1 is used, the catalyst layer can be satisfactorily transferred to the electrolyte membrane. However, in the transfer film of Patent Document 1, it is inevitable that a part of the fluorine-based release component is transferred to the solid electrolyte membrane together with the catalyst layer, which has a problem that adversely affects the performance of the fuel cell. ing.

  Patent Document 2 is a film having a polyester film as a main structure, and a peak derived from an organosilicon compound is not detected in any surface by X-ray photoelectron spectroscopy measurement, and at least one surface is A release film is disclosed which is mainly composed of polyolefin and has a heat peeling force of 80 mN / cm or less on the surface.

However, when a catalyst layer transfer film is prepared using the release film described in Patent Document 2, there is a problem that the catalyst layer is easily lost. Therefore, the transfer of the catalyst layer to the electrolyte membrane is insufficient, and excellent performance cannot be imparted to the fuel cell.
JP 2003-285396 A JP 2006-150812 A

  An object of the present invention is to provide a transfer film in which the electrolyte membrane is not contaminated by a release component and the catalyst layer is not easily lost.

  The present inventor has intensively studied in order to solve the above problems. As a result, it has been found that when a specific laminated film is used as the base film of the transfer film, a desired transfer film can be obtained and the above problems can be solved. The present invention has been completed based on such findings.

This invention provides the catalyst layer transfer film shown to the following items 1-3.
Item 1. A film for transferring a catalyst layer for a fuel cell, in which a catalyst layer is formed on one surface of a base film,
The base film is a laminate of a film A made of a resin having a glass transition temperature of 50 ° C. or more and a melting point of 200 ° C. or more and a film B made of an olefin resin having a glass transition temperature of less than 50 ° C. and a melting point of 200 ° C. or more. A film,
The resin constituting the film A is at least one selected from the group consisting of polyimide, polyethylene terephthalate, polysulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyarylate, and polyethylene naphthalate. And
The resin constituting the film B is poly-4-methylpentene-1,
The catalyst layer is formed on the film B side,
Catalyst layer transfer film.
Item 2. Item 2. The catalyst layer transfer film according to Item 1, wherein the total thickness of the laminated film is in the range of 30 to 200 µm.
Item 3. The resin constituting the film A is a polyimide, polyethylene terephthalate, Po Li polyphenylene sulfide, polyether ether ketone, Po Li ethylene naphthalate, the catalyst layer transfer film according to claim 1 or 2.

Catalyst layer transfer film The catalyst layer transfer film of the present invention is a transfer film in which a catalyst layer is formed on one surface of a base film. A cross-sectional view showing an example of the catalyst layer transfer film of the present invention is shown in FIG.

Base film The base film of the present invention comprises a film A composed of a resin having a glass transition temperature of 50 ° C or higher and a melting point of 200 ° C or higher, and an olefin resin having a glass transition temperature of less than 50 ° C and a melting point of 200 ° C or higher. It is a laminated film with film B.

  As the resin constituting the film A, known resins can be widely used as long as the glass transition temperature is 50 ° C. or higher and the melting point is 200 ° C. or higher. For example, polyimide, polyethylene terephthalate (PET), polysulfone, Examples thereof include polymer films such as polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyarylate, and polyethylene naphthalate (PEN). As the resin constituting the film A, a resin having a glass transition temperature of 65 ° C. or higher and a melting point of 250 ° C. or higher is preferable, and specifically, PET, PEN or the like is preferable. The film A may be any of non-axial stretching, uniaxial stretching, and biaxial stretching.

As the olefin resin constituting the film B, known olefin resins can be widely used as long as the glass transition temperature is less than 50 ° C. and the melting point is 200 ° C. or more. For example, poly-4- Mention may be made of methylpentene- 1 . As the olefin resin constituting the film B, an olefin resin having a glass transition temperature of less than 45 ° C. and a melting point of 220 ° C. or more is preferable, and specifically, poly-4-methylpentene-1 is preferable. The film B may be any of non-axial stretching, uniaxial stretching and biaxial stretching.

In this specification, melting | fusing point and glass transition temperature of resin are measured by the method shown below.
Melting point:
The melting point was measured by a DSC (Differential Scanning Calorimetry) method using a differential scanning calorimeter (DSC-60 manufactured by Shimadzu Corporation). The outline of this method is to measure changes in calorie (exotherm and endotherm) when a sample and a reference material are heated at a constant rate. For example, when polyethylene, which is a crystalline polymer, is heated (heated) by DSC, the crystal is melted by absorbing heat at about 100 to 130 ° C. The heat absorption at this time is measured by DSC as an endothermic peak.
Glass-transition temperature:
The glass transition temperature was measured by a dynamic mechanical analysis (DMA) method using a dynamic viscoelasticity measuring apparatus. In this method, a sample is subjected to sinusoidal stress or strain by bending or pulling, and the dynamic storage elastic modulus, dynamic loss elastic modulus and loss tangent are obtained as a function of temperature, and the glass transition temperature is determined by This is a method of measuring from the peak temperature of loss tangent.

  The total thickness of the laminated films is preferably 30 to 200 μm, preferably 50 to 150 μm, from the viewpoints of workability and economical efficiency for forming a catalyst layer on the base film.

  The thickness ratio of the film B in the laminated film is preferably 1 to 95%, more preferably 10 to 80%, still more preferably 20 to 70%, and particularly preferably 30 to 50% of the entire laminated film.

  In the present invention, the film B may be subjected to a surface treatment. Examples of the surface treatment include mechanical treatment that physically forms surface irregularities with a metal brush, sandblast, etc., mat treatment, corona discharge treatment, plasma discharge treatment, and ultraviolet treatment.

Catalyst Layer In the present invention, the catalyst layer is formed on the film B side.

  The catalyst layer is known and generally contains carbon particles supporting catalyst particles and a hydrogen ion conductive polymer electrolyte.

  Here, as a catalyst particle, platinum, a platinum compound, etc. are mentioned, for example. Examples of the platinum compound include an alloy of platinum and at least one metal selected from the group consisting of ruthenium, palladium, nickel, molybdenum, iridium, iron and the like.

  Examples of the hydrogen ion conductive polymer electrolyte include perfluorosulfonic acid-based fluorine ion exchange resins.

  In forming the catalyst layer on the base film, the carbon particles supporting the catalyst particles and the hydrogen ion conductive polymer electrolyte are mixed and dispersed in a suitable solvent to form a paste. This paste is preferably applied onto the film B of the base film according to a known method so that the catalyst layer has a desired layer thickness.

  Examples of the solvent used include various alcohols, various ethers, various dialkyl sulfoxides, water, or a mixture thereof.

  The method of applying the paste is not particularly limited, and for example, general methods such as knife coater, bar coater, spray, dip coater, spin coater, roll coater, die coater, curtain coater, screen printing, etc. are applied. it can.

  After applying such paste, the catalyst layer is formed by drying. A drying temperature is about 40-100 degreeC normally, Preferably it is about 60-80 degreeC. Although depending on the drying temperature, the drying time is usually about 5 minutes to 2 hours, preferably about 30 minutes to 1 hour.

  The thickness of the catalyst layer is usually about 10 to 50 μm, preferably about 15 to 30 μm.

Catalyst Layer-Electrolyte Membrane Laminate The catalyst layer-electrolyte membrane laminate of the present invention is obtained by forming catalyst layers on both sides of the electrolyte membrane. An example of a cross-sectional view of the catalyst layer-electrolyte membrane laminate of the present invention is shown in FIG.

  The electrolyte membrane (catalyst layer-electrolyte membrane laminate) on which the catalyst layer of the present invention is laminated is, for example, after the transfer film is arranged and pressed so that the catalyst layer surface of the transfer film of the present invention faces the electrolyte membrane surface It is manufactured by peeling the base film of the transfer film. By repeating this operation twice, a catalyst layer-electrolyte membrane laminate in which the catalyst layer surface is laminated on both surfaces of the electrolyte membrane is produced.

  In consideration of workability, the catalyst layer surface is preferably laminated on both surfaces of the electrolyte membrane at the same time. In this case, for example, the transfer film may be disposed so that the catalyst layer surface of the transfer film of the present invention faces both surfaces of the electrolyte membrane and pressurized, and then the base film of the transfer film may be peeled off.

  The electrolyte membrane used is a known one. The thickness of the electrolyte membrane is usually about 20 to 250 μm, preferably about 20 to 80 μm. Specific examples of the electrolyte membrane include “Nafion” (registered trademark) membrane manufactured by DuPont, “Flemion” (registered trademark) membrane manufactured by Asahi Glass Co., Ltd., and “Aciplex” (registered trademark) membrane manufactured by Asahi Kasei Corporation. And “Gore Select” (registered trademark) membrane manufactured by Gore.

  The pressure level is usually about 0.5 to 10 Mpa, preferably about 1 to 10 Mpa in order to avoid transfer defects. Further, it is preferable to heat the pressure surface during this pressure operation in order to avoid transfer failure. The heating temperature is usually about 80 to 200 ° C., preferably about 135 to 150 ° C., in order to avoid breakage, modification and the like of the electrolyte membrane.

Electrode-electrolyte membrane assembly The electrode-electrolyte membrane assembly of the present invention is produced by placing electrode substrates on both sides of a catalyst layer-electrolyte membrane laminate and applying pressure.

  The electrode base material is well known, and various electrode base materials constituting a fuel electrode and an air electrode can be used.

  The pressure level is usually about 0.1 to 100 Mpa, preferably about 5 to 15 Mpa. It is preferable to heat at the time of this pressurization operation, and heating temperature may be about 120-150 degreeC normally.

  According to the present invention, it is possible to provide a transfer film in which the electrolyte membrane is not contaminated by the release component and the catalyst layer is not easily lost.

  By using the transfer film of the present invention, a uniform catalyst layer can be formed on the electrolyte membrane.

  The transfer film of the present invention has excellent heat resistance.

  Therefore, according to the present invention, it is possible to provide a transfer film for producing a catalyst layer-electrolyte membrane laminate that can transfer the catalyst layer to the electrolyte membrane satisfactorily and that does not adversely affect the performance of the fuel cell.

  Therefore, if the catalyst layer-electrolyte membrane laminate of the present invention is used, a high-quality fuel cell with excellent battery performance can be produced.

  The present invention will be further clarified by the following examples.

Reference example (creation of laminated film)
Film A and various films B shown below are adhesives (LX-703VL manufactured by Dainippon Ink & Chemicals, Ltd. as the main agent, and KR-90 manufactured by Dainippon Ink & Chemicals, Inc. as the curing agent. Various laminated films were produced by bonding using the adhesive used.
Film A;
(A-1) Polyethylene terephthalate (PET, ester film E5100 manufactured by Toyobo Co., Ltd., thickness 100 μm, glass transition temperature 80 ° C., melting point 260 ° C.)
Film B;
(B-1) Poly-4-methylpentene-1 (TPX, Mitsui Chemicals Opuran, thickness 25 μm, glass transition temperature 40 ° C., melting point 230 ° C.)
(B-2) Polyethylene (PE, Hytron PG manufactured by Tamapoly Co., Ltd., thickness 25 μm, glass transition temperature 80 ° C., melting point 130 ° C.)
(B-3) Polyethylene terephthalate (PET, Diafoil manufactured by Mitsubishi Chemical Polyester Co., Ltd., thickness 25 μm, glass transition temperature 70 ° C., melting point 260 ° C.)
(B-4) Fluorine-based resin (Aflex manufactured by Asahi Glass Co., Ltd., thickness 25 μm, glass transition temperature 40 ° C., melting point 260 ° C.)
The laminated film of (A-1) and (B-1) is hereinafter referred to as “laminated film (I)”, the laminated film of (A-1) and (B-2) is hereinafter referred to as “laminated film (II)”, The laminated film of (A-1) and (B-3) is hereinafter referred to as “laminated film (III)”, and the laminated film of (A-1) and (B-4) is hereinafter referred to as “laminated film (IV)”. .

Example 1
Platinum ruthenium-supported carbon (Pt: 27.2% by weight, Ru: 28.7% by weight) (Tanaka Kikinzoku Co., Ltd., TEC62E58) 10 parts by weight and 5% by weight electrolyte solution (manufactured by DuPont, DE-520, solvent) : 1-propanol / water = 1/1 (weight ratio)) was added to 100 parts by weight of isopropyl alcohol and 2 parts by weight of propylene glycol, and mixed and dispersed to prepare a catalyst layer forming paste.

  The catalyst layer forming paste was applied to the (B-1) side of the laminated film (I) using a blade coater so that the thickness after drying was 20 μm and dried at 85 ° C. A transfer film was produced.

Comparative Examples 1-3
A comparative catalyst layer transfer film was produced in the same manner as in Example 1 except that the laminated film (II), the laminated film (III) or the laminated film (IV) was used instead of the laminated film (I). .

Test example 1 (suitability for printing on transfer film)
The printing suitability of the transfer film was evaluated as follows. In Example 1 and Comparative Examples 1 to 3, the printing quality when the paste for forming the catalyst layer was applied to the laminated film (I), the laminated film (II), the laminated film (III) and the laminated film (IV) was as follows. It was evaluated with. That is, the case where the catalyst layer forming paste can be easily applied and a uniform catalyst layer can be formed is ○, the case where the catalyst layer forming paste is difficult to apply and the catalyst layer cannot be formed is × As evaluated.

  The results are shown in Table 1.

Test example 2 (transfer performance of transfer film)
Each of the catalyst layer transfer films produced in Example 1 and Comparative Examples 1 and 2 was cut to 5 × 5 cm, and the hydrogen ion conductive electrolyte membrane (DuPont, Nafion 112, film thickness 50 μm) cut to 8 × 8 cm was used. On both sides, a transfer film was placed so that the catalyst layer surface of the transfer sheet faced both surfaces of the electrolyte membrane, and transfer was performed at a temperature of 180 ° C. and a pressure of 6.5 MPa to produce a catalyst layer-electrolyte membrane laminate.

  The transfer rate (%) when the catalyst layer was transferred to the electrolyte membrane was calculated according to the following formula.

  Here, the amount of catalyst before transfer is the weight obtained by subtracting the weight of the laminated film after wiping off the catalyst layer from the weight of the catalyst layer transfer film before transfer. The amount of catalyst after transfer is a weight obtained by subtracting the weight of the laminated film after wiping off the catalyst layer from the weight of the catalyst layer transfer film after transfer.

  A transfer film having a transfer rate of 97% or more was evaluated as “◯”, a transfer film having a transfer rate of 95% or more and less than 97% was evaluated as Δ, and a transfer film having a transfer rate of less than 95% was evaluated as “X”.

  The results are shown in Table 1.

  From Table 1, it is clear that the catalyst layer transfer film obtained in Example 1 has good printing suitability and excellent transfer performance.

Test Example 3 (Heat peeling force of transfer film)
The heat peeling force of the catalyst layer transfer film obtained in Example 1 was measured according to the following method. Acrylic adhesive tape “No. 31B” (manufactured by Nitto Denko Corporation) was attached to the (B-1) surface of the laminated film (I), and heat treatment was performed in a hot air oven at 100 ° C. for 1 hour. After heat treatment, after cooling at room temperature for 1 hour, 180 ° peeling is performed at a tensile rate of 300 mm / min with a tensile tester, and the value obtained by dividing the average peeling load in the area where peeling is stable by the width of the adhesive tape is heated. Power.

  As a result, the heat peeling force of the catalyst layer transfer film obtained in Example 1 was 1667 mN / cm.

FIG. 1 is a cross-sectional view of the catalyst layer transfer film of the present invention. FIG. 2 is a cross-sectional view of the catalyst layer-electrolyte membrane laminate.

Claims (3)

A film for transferring a catalyst layer for a fuel cell, in which a catalyst layer is formed on one surface of a base film,
The base film is a laminate of a film A made of a resin having a glass transition temperature of 50 ° C. or more and a melting point of 200 ° C. or more and a film B made of an olefin resin having a glass transition temperature of less than 50 ° C. and a melting point of 200 ° C. or more. A film,
The resin constituting the film A is at least one selected from the group consisting of polyimide, polyethylene terephthalate, polysulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyarylate, and polyethylene naphthalate. And
The resin constituting the film B is poly-4-methylpentene-1,
The catalyst layer is formed on the film B side,
Catalyst layer transfer film.   The catalyst layer transfer film according to claim 1, wherein the total thickness of the laminated film is in the range of 30 to 200 μm. The resin constituting the film A is a polyimide, polyethylene terephthalate, Po Li polyphenylene sulfide, polyether ether ketone, Po Li ethylene naphthalate, the catalyst layer transfer film according to claim 1 or 2.

Images