JP2023023299A - Fuel cell gasket and method for manufacturing fuel cell gasket - Google Patents

Abstract

To provide a fuel cell gasket that suppresses the formation of voids on the surface of a gasket material.SOLUTION: A fuel cell gasket is a two-layer adhesive having a first layer of rubber adhesive and a second layer containing a UV curing agent on the outer layer of the first layer. A closed space is formed by the second layer, the first layer is pressurized to reduce the viscosity thereof, thereby making generated air bubbles easily movable, and the air bubbles are discharged by inducing cleavage of a thin wall portion with inner pressure to form voids in the surface of the gasket member, whereby deterioration of the adhesiveness of the fuel cell gasket can be suppressed.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to fuel cell gaskets and methods of manufacturing fuel cell gaskets.

Patent Literature 1 discloses a fuel cell that reduces variations in the degree of bubble removal while reducing bubbles in an adhesive layer used in the fuel cell. This fuel cell comprises an electrolyte membrane-electrode assembly including an electrolyte membrane, an electrode catalyst layer, and a gas diffusion layer, an adhesive layer formed on the peripheral edge of the assembly, a resin frame surrounding it, and the electrolyte membrane. - a separator having a projection projecting from the periphery of the electrode assembly.

JP 2018-73523 A

The present disclosure provides a fuel cell gasket that suppresses the formation of voids on the surface.

A fuel cell gasket according to the present disclosure includes a first layer that is a rubber-based adhesive and a second layer that includes a UV curing agent so as to cover the outer periphery of the first layer. The second layer has a thin portion thinner than other portions of the outer periphery of the second layer or an opening portion where the second layer does not cover the first layer.

In the fuel cell gasket of the present disclosure, the closed space is formed by the second layer, and the viscosity of the first layer is reduced by pressurizing the first layer, thereby facilitating the movement of generated air bubbles. Therefore, when the thin portion is cleaved by the internal pressure, the generated air bubbles can be discharged, and the formation of voids in the rubber adhesive can be suppressed.

Cross-sectional view of the fuel cell gasket in Embodiment 1 Sectional view of a fuel cell using the fuel cell gasket according to Embodiment 1 Sectional view of a fuel cell gasket having an opening according to Embodiment 1 Sectional view of a fuel cell using a fuel cell gasket having openings according to Embodiment 1 Schematic diagram showing steps of applying and curing a fuel cell gasket in Embodiment 1. FIG. FIG. 2 is a cross-sectional view showing application of the gasket for a fuel cell according to Embodiment 1 to the separator of the fuel cell; FIG. 2 is a cross-sectional view showing a state in which the separator of the fuel cell using the fuel cell gasket according to Embodiment 1 is in contact with the electrolyte membrane-electrode assembly; Sectional view showing a state in which the separator of the fuel cell using the fuel cell gasket according to Embodiment 1 is in contact with the electrolyte membrane-electrode assembly, and gas is released from the first layer. Sectional view of a fuel cell showing a fuel cell gasket having an opening according to another embodiment Sectional view of a separator to which a fuel cell gasket is applied according to another embodiment

(Knowledge, etc. on which this disclosure is based)
At the time when the inventors came up with the present disclosure, there was a technique of applying a rubber adhesive to a separator as a fuel cell gasket. It was plasticized under heat and pressure conditions, and its viscosity decreased. At this time, the cross-linking reaction gas and the volatilized gas of the solvent form bubbles, and the generated bubbles move quickly to the low-pressure gas vent hole and are discharged to the outside.

On the other hand, if the pressurization is not sufficient, the reaction gas and volatile gas remain in the rubber adhesive layer, forming voids, resulting in a decrease in gas sealing performance.

In order to prevent this, conventionally, the closed space is filled with a rubber adhesive, sealed and pressurized, or the generated air bubbles are discharged by applying a thin and uniform coating.

However, it is technically difficult to form a closed space by filling the space between the electrolyte membrane-electrode assembly sandwiched between the anode separator and the cathode separator of a fuel cell with a rubber adhesive, and a rubber-based adhesive is used. The adhesive is thick and varies in size. For this reason, there is a problem that it is difficult to apply the rubber adhesive without generating voids in the fuel cell gasket.

Under these circumstances, the inventors investigated the mechanism of gas generation and designed the structure of a fuel cell gasket composed of a two-layer adhesive.

Then, the inventors have found that a closed space can be constructed by enclosing the rubber adhesive by coating the outer layer of the rubber adhesive with a UV curable adhesive and curing the adhesive at the same time. In addition, by providing a thin portion that is thinner than other portions on the contact surface between the UV curable adhesive and the electrolyte membrane-electrode assembly and the contact surface with the separator, air bubbles generated in the rubber adhesive are eliminated. I got the idea that it can be easily released to the outside.

Accordingly, the present disclosure provides a fuel cell gasket comprising a first layer of rubber adhesive and a second layer containing a UV curing agent on its outer layer. This fuel cell gasket is a two-layer adhesive that has a thin portion where the second layer is thinner than the other portion on a part of the contact surface with the electrolyte membrane-electrode assembly and the contact surface with the separator. there is As a result, a closed space is formed in the second layer, and the viscosity of the first layer is reduced by pressurizing the first layer, making it easier for the air bubbles generated in the first layer to move, and the thin portion of the second layer is split by the internal pressure. Then, bubbles generated from the first layer are discharged, and formation of voids can be suppressed.

Hereinafter, embodiments will be described in detail with reference to the drawings. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially the same configurations may be omitted.

It should be noted that the accompanying drawings and the following description are provided for a thorough understanding of the present disclosure by the parties and are not intended to limit the claimed subject matter thereby.

(Embodiment 1)
Embodiment 1 will be described below with reference to FIGS. 1 to 4. FIG.

[1-1. composition]
In FIG. 1, the fuel cell gasket 110 includes a rubber adhesive layer 111, a UV curable adhesive layer 112 configured to cover the outer periphery of the rubber adhesive layer 111, and a portion of the UV curable adhesive layer 112. A thin portion 113 is provided in the portion.

A highly durable fluorine-based adhesive is used for the rubber-based adhesive layer 111 .

The UV curing adhesive layer 112 uses a perfluoropolyether UV curing adhesive.

In FIG. 2, the fuel cell 100 includes an electrolyte membrane-electrode assembly 104, a separator 106, and a fuel cell gasket 110. As shown in FIG.

The electrolyte membrane-electrode assembly 104 includes an electrolyte membrane 101, an anode catalyst layer 102 arranged on one side across the electrolyte membrane 101, a cathode catalyst layer 103 arranged on the other side, and an anode catalyst layer 102. and a gas diffusion layer 105 arranged outside the cathode catalyst layer 103 .

The electrolyte membrane 101 functions to transport hydrogen ions generated in the anode catalyst layer 102 to the cathode catalyst layer 103, and is composed of a polymer material having hydrogen ion conductivity. It is composed of a perfluorosulfonic acid-based polymer material having an acid group.

The anode catalyst layer 102 functions to promote an electrochemical reaction in which hydrogen contained in the hydrogen-containing gas supplied to the anode catalyst layer 102 from the gas flow path 107 of the separator 106 on the anode side is dissociated into hydrogen ions. It contains carbon particles supporting Pt) and a polymer electrolyte resin.

The cathode catalyst layer 103 contains hydrogen ions that move from the anode catalyst layer 102 through the electrolyte membrane 101 to the cathode catalyst layer 103 and air that is supplied to the cathode catalyst layer 103 from the gas flow path 107 of the separator 106 on the cathode side. It functions to promote an electrochemical reaction that produces water from the oxygen that is released, and contains platinum (Pt)-supported carbon particles and a polymer electrolyte resin.

The gas diffusion layer 105 functions to supply gas to the anode catalyst layer 102 or the cathode catalyst layer 103 and to transfer electrons between the anode catalyst layer 102 or the cathode catalyst layer 103, thereby improving gas permeability and electron conductivity. The main component is a conductive carbon paper that has both properties.

The separator 106 is made of compressed carbon, which is a conductive member with no gas permeability. Gas flow paths 107 for supplying hydrogen-containing gas or air to the gas diffusion layer 105 are formed on the surface of the separator 106 on the side of the gas diffusion layer 105 .

The fuel cell gasket 110 is arranged between the separator 106 and the electrolyte membrane-electrode assembly 104 in order to block or suppress leakage of hydrogen-containing gas to the outside, and the rubber-based adhesive layer 111 as the first layer is disposed between the separator 106 and the electrolyte membrane-electrode assembly 104. and a UV curable adhesive layer 112, which is a rubber-based adhesive configured to form a closed space.

The UV-curing adhesive layer 112 is a rubber-based adhesive that cures when irradiated with ultraviolet rays. , a thin portion 113 is provided in a portion of the UV curable adhesive layer 112 .

[1-2. Production method]
A manufacturing method according to the first embodiment will be described with reference to FIGS. 5, 6A, 6B, and 6C.

First, the two-layer adhesive application device 121 shown in FIG. , is applied linearly on the separator 106 so as to be 0.5 g/cm 2 or more. An example of the two-layer adhesive applicator 121 is a dispenser.

Then, the UV irradiation device 122 irradiates the translucent container 120, which can transmit and irradiate from the outside, with ultraviolet rays. The ultraviolet rays that pass through the translucent container 120 are applied to the UV curing adhesive layer 112 of the fuel cell gasket 110 . This initiates the curing reaction of the UV curable adhesive layer 112 .

The tip of the translucent container 120 has an indentation (not shown) so that the shape of the tip becomes the thin portion 113. During UV irradiation, the indentation forms depressions on the upper and lower surfaces of the second layer. be done. Specifically, the aperture at the tip of the light-transmitting container 120 is formed with a throttle port that protrudes toward the inner diameter side of the aperture so that one vertex of the triangle faces each other, so that the UV curing adhesive can be applied to the aperture port. When passing through, it is processed into a concave shape, and this concave becomes the thin portion 113 of the UV curing adhesive layer 112 .

FIG. 6A shows a sectional view of the fuel cell gasket 110 and the separator 106 formed as described above.

Next, as shown in FIG. 6B, the electrolyte membrane-electrode assembly 104 is placed on the separator 106. At this time, the fuel cell gasket 110 covers the outer edges of the separator 106 and the electrolyte membrane-electrode assembly 104. are arranged as follows.
A thin portion 113 provided in a portion of the UV curable adhesive layer 112 contacts the electrolyte membrane-electrode assembly 104 and the separator 106 .

In FIG. 6C, heat and pressure are applied to the electrolyte membrane-electrode assembly 104, the separator 106 and the fuel cell gasket 110. In FIG.

At this time, the cross-linking reaction of the rubber-based adhesive layer 111 increases the internal pressure of the first rubber-based adhesive layer 111 and lowers the viscosity, thereby generating air bubbles 108 in the rubber-based adhesive layer 111 .

Further, the thin portion 113 of the UV curing adhesive layer 112 configured to cover the rubber adhesive layer 111 is cleaved by deformation of the UV curing adhesive layer 112 due to pressure.

As a result, the air bubbles 108 generated in the rubber-based adhesive layer 111 are discharged out of the fuel cell gasket 110 through the cleaved thin portion 113, and the electrolyte membrane-electrode assembly 104 contacts the separator 106. is released to the outside through the gap 109 of the .

Further, a cross-linking reaction proceeds in the rubber-based adhesive layer 111 due to heating and pressurization, and after the fuel cell gasket 110 is cured, the rubber-based adhesive layer 111 becomes an elastic body. By being closed and generating a reaction force, it functions as an adhesive and as a rubber seal material at the same time.

[1-3. effects, etc.]
As described above, in the present embodiment, fuel cell 100 includes electrolyte membrane-electrode assembly 104, separator 106, and fuel cell gasket 110. As shown in FIG.

The electrolyte membrane-electrode assembly 104 includes an electrolyte membrane 101, an anode catalyst layer 102 arranged on one side across the electrolyte membrane 101, a cathode catalyst layer 103 arranged on the other side, and an anode catalyst layer 102. and a gas diffusion layer 105 arranged outside the cathode catalyst layer 103 .

The fuel cell gasket 110 includes a rubber-based adhesive layer 111, a UV-curable adhesive layer 112 configured to cover the rubber-based adhesive layer 111, and a thin portion provided in a portion of the UV-curable adhesive layer 112. 113.

As a result, the thin portion 113 provided in a part of the UV curable adhesive layer 112 is cleaved when heated and pressurized, and the gas generated by the cross-linking reaction of the rubber adhesive layer 111 is released as bubbles 108. It can be moved and released to the outside through the thin portion 113 .

Therefore, it is possible to suppress the formation of voids inside the rubber-based adhesive layer 111, thereby suppressing the deterioration of the adhesive strength of the fuel cell gasket 110 due to voids remaining on the surface of the fuel cell gasket 110. can be done.

In this embodiment, the fuel cell gasket 110 has the thin portion 113 of the UV curable adhesive layer 112, but the thin portion 113 may have an opening (not shown) in advance. As a result, air bubbles 108 generated in the rubber-based adhesive layer 111 are discharged through the opening of the thin portion 113 .

Therefore, the discharge path of the air bubbles 108 can be reliably discharged from the contact surface (not shown) with the electrolyte membrane-electrode assembly 104 and the contact surface (not shown) with the separator. The gas generated by the crosslinking reaction of the rubber-based adhesive layer 111 can be prevented from leaking out from other than the openings of the UV-curable adhesive layer 112 of the second layer.

Further, in the present embodiment, the fuel cell gasket 110 has a second layer of UV curing adhesive layer 112 made of a rubber adhesive. Thereby, it is possible to match the coefficient of linear expansion and stretchability with those of the rubber-based adhesive layer 111 of the first layer. Therefore, when a load for fastening is applied, the first layer and the second layer follow each other and deform, so the rubber adhesive of the first layer leaks from the UV curing adhesive layer 112 of the second layer. You can prevent it from coming out.

[1-4. Modification]
In this embodiment, the fuel cell gasket 110 uses a fluorine-based rubber adhesive for the rubber-based adhesive layer 111 of the first layer. As a result, the rubber-based adhesive layer 111 is excellent in mechanical resistance such as chemical resistance and compression set. Therefore, it is possible to maintain excellent long-term durability as sealing performance.

The adhesive for the rubber-based adhesive layer 111, which is the first layer, is not particularly limited as long as it does not poison the anode catalyst layer 102 and the cathode catalyst layer 103 of the electrolyte membrane-electrode assembly 104. FIG. Thermosetting elastomers such as fluorine rubber, silicone rubber, natural rubber, EPDM, butyl rubber, adhesives using latex such as isoprene rubber and butadiene rubber, liquid polybutadiene, polyisoprene, polychloroprene, silicone rubber, etc. Although not limited to these compounds, fluororubber materials are desirable from the viewpoint of chemical resistance and mechanical resistance.

The adhesive of the second layer, UV curing adhesive layer 112, is preferably silicone rubber. As a result, since the surface of the silicone polymer material, which is the main component of the silicone rubber, is covered with hydrophobic methyl groups, it can impart water repellency, and since it has low polarity, it can impart low hygroscopicity. The sealing function can be maintained in the internal high-temperature and high-humidity environment.

However, the adhesive for the UV-curable adhesive layer 112, which is the second layer, is not particularly limited as long as it contains a photopolymerization initiator for UV-curing. It can be anything that can be reacted, cured, crosslinked, or polymerized in the presence of UV light. Examples of suitable UV curable include those composed at least in part of maleimides, acrylates, vinyl ethers and styrenes.

Although an example of irradiating the UV curing adhesive layer 112 with UV has been described, there is no particular limitation as long as it is a method of cross-linking with a photopolymerization initiator. There are a heat treatment involving conditions such as pressurization and humidification, and an irradiation method of irradiating with light (active energy ray), each of which may be used alone or in combination. Here, active energy rays include radiation such as α rays and β rays, electromagnetic waves such as γ rays and X rays, electron beams (EB), ultraviolet rays with a wavelength of about 100 to 400 nm, and visible rays with a wavelength of about 400 to 800 nm. It includes all light in a broad sense such as ultraviolet rays, preferably ultraviolet rays.

In addition, although a dispenser device has been used as a device for applying the fuel cell gasket 110, it is not particularly limited as long as it is a method for applying the fuel cell gasket 110. FIG. Coating methods such as screen printing, dip printing, gravure coating, and die coating may be used alone or in combination, but a dispenser device is preferably used. The dispenser device can conveniently apply to complex substrates.

Note that the above-described embodiment is for illustrating the technology in the present disclosure, and various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or equivalents thereof. Also, it is possible to combine the constituent elements described in the first embodiment to form a new embodiment.
(Other embodiments)
Next, referring to FIGS. 7 and 8, a description will be given of another embodiment in which the configurations of the thin portion 113 and the opening 114 are different from those of the first embodiment.

The opening 114 of the fuel cell gasket 110 is provided in a part of the thin portion 113 and is desirably arranged so as to contact the electrolyte membrane-electrode assembly 104 and the separator 106, as shown in FIG. It may be arranged at a plurality of locations. If there are multiple locations, the gas can be easily discharged to the outside, and the formation of voids can be suppressed.

Further, the fuel cell gasket 110 may be applied to the separator 106 so that the fuel cell gasket 110 is installed in the seal groove 130 provided in the separator 106 as shown in FIG. By using the separator 106 having the seal groove 130, it is possible to restrict the wetting and spreading of the fuel cell gasket 110 at the time of application, so that the seal line can be maintained even when applying to a corner portion with a large curvature.

INDUSTRIAL APPLICABILITY The present disclosure is applicable as a sealing material for fuel cells. Specifically, the present disclosure is applicable to polymer electrolyte fuel cells such as high-pressure tanks, fuel cell vehicles, and stationary fuel cells.

REFERENCE SIGNS LIST 100 Fuel cell 101 Electrolyte membrane 102 Anode catalyst layer 103 Cathode catalyst layer 104 Electrolyte membrane-electrode assembly 105 Gas diffusion layer 106 Separator 107 Gas channel 108 Bubbles 109 Gap 110 Gasket for fuel cell 111 Rubber-based adhesive layer 112 UV curing adhesion Agent layer 113 Thin portion 114 Opening 120 Translucent container 121 Two-layer adhesive application device 122 UV irradiation device 130 Seal groove

Claims (4)

Having a first layer that is a rubber-based adhesive and a second layer that is a rubber-based adhesive containing a UV curing agent so as to cover the outer periphery of the first layer,
The second layer partially has a thin portion thinner than other parts of the outer periphery of the second layer or an opening that does not cover the first layer,
Gaskets for fuel cells. The first layer is a fluororubber adhesive,
The fuel cell gasket according to claim 1. wherein the second layer is a silicone-based rubber adhesive,
The fuel cell gasket according to claim 1 or 2. an electrolyte membrane-electrode assembly composed of an electrolyte membrane, an anode arranged on one side of the electrolyte membrane, and a cathode arranged on the other side;
a pair of separators disposed on both sides of the anode and the cathode of the electrolyte membrane-electrode assembly;
The fuel cell gasket according to any one of claims 1 to 3, which is interposed between the electrolyte membrane-electrode assembly and the separator, and the thin portion faces the separator;
fuel cell.

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