JP5177619B2 - Method for manufacturing a gasket-integrated part for a fuel cell - Google Patents

Description

The present invention includes a gasket for sealing a flow path formed between fuel cells of a fuel cell stack, and a gasket integrated part in which GDLs on both sides in the thickness direction of the power generator of the fuel cell are integrated. It relates to a method of manufacturing .

  A fuel cell is a power generator in which GDL (Gas Diffusion Layer) is arranged on both sides in the thickness direction of a MEA (Membrane Electrode Assembly) provided with a pair of electrode layers on both sides of an electrolyte membrane, Alternatively, it has a stack structure in which a power generation body in which a catalyst electrode layer and a gas diffusion electrode layer made of GDL are disposed on both surfaces of an electrolyte membrane is sandwiched between separators to form fuel cells, and a number of these fuel cells are stacked.

  Then, the oxidizing gas (air) is supplied from the oxidizing gas flow path formed on one side of each separator to the cathode side of the power generator via one GDL, and the fuel gas (hydrogen) is supplied to each separator. The fuel gas flow path formed on the other surface is supplied to the anode side of the power generator through the other gas diffusion layer, and the electrochemical reaction, which is the reverse reaction of water electrolysis, that is, water from hydrogen and oxygen is removed. Electric power is generated by the reaction to be generated. For this reason, each fuel battery cell is provided with a gasket for sealing fuel gas, oxidizing gas, water generated by the above-described electrochemical reaction, excess air, and the like.

  As gaskets, for example, a rubber-only one that is molded as a separate member and then fitted into a groove formed in the separator, or one that adheres to the separator is common, but the assembly work is complicated and time-consuming. There is.

  Therefore, in recent years, a reinforcing frame made of a synthetic resin film is attached to the outer peripheral portion of the power generation body between the separators by a method such as thermocompression bonding, and gaskets that are in close contact with the separators on both sides are attached to both sides of the reinforcing frame. A method is adopted in which the gasket is integrated with the power generation body (MEA) to form a stack assembly in a simplified manner (see the following patent document).

Patent No. 3052536 WO00 / 64995 WO2002 / 043172

  However, in such a method, there is a concern that the power generation body may be thermally and mechanically damaged during thermocompression bonding of the reinforcement frame body, and the interface between the two is caused by the difference in the linear expansion coefficient between the reinforcement frame body and the power generation body. There is also a risk of peeling. Moreover, in order to integrate the reinforcing frame directly into the power generation body, the reinforcing frame has to be electrically insulating.

  The present invention has been made in view of the above points, and the technical problem thereof is to integrate the power generator in the fuel cell together with the reinforcing frame in order to simplify stack assembly. An object of the present invention is to provide an improved gasket without causing inconvenience due to thermocompression bonding of a reinforcing frame.

As a means for effectively solving the technical problem described above, the method for manufacturing a fuel cell gasket- integrated part according to the invention of claim 1 includes sandwiching a power generator including GDLs on both sides in the thickness direction in a mold. The reinforcing frame is placed on both surfaces of the reinforcing frame in advance in a gasket forming cavity defined between the outer peripheral portion of the power generator and the inner surface of the mold in a state of being separated from the power generator. Positioning and fixing through an elastic protrusion made of an integrally molded rubber-like elastic material, filling the gasket molding cavity with liquid rubber and impregnating part of it into the outer periphery of the GDL, this liquid rubber Is cured and bonded to the reinforcing frame . In addition, the power generator here refers to an MEA (Membrane Electrode Assembly) in which a pair of electrode layers are provided on both sides of the electrolyte membrane and GDLs disposed on both sides in the thickness direction, or an electrolyte membrane. A gas diffusion electrode layer consisting of a catalyst electrode layer and a GDL on both sides is a generic term. GDL is a gas diffusion layer (Gas Diffusion Layer). This includes the electrode layer.

According to the method for manufacturing a gasket-integrated part for a fuel cell according to the first aspect of the present invention, the GDL on both sides in the thickness direction of the power generation body of the fuel cell and the reinforcing frame spaced apart on the outer peripheral side thereof Since a fuel cell gasket integrated part having a structure integrated through a gasket reinforced with a frame can be obtained , assembly of the fuel cell stack can be simplified. In addition, since the reinforcing frame is spaced apart on the outer peripheral side of the power generation body and a gasket made of a cured liquid rubber that is an insulator is interposed therebetween, the linear expansion between the power generation body and the reinforcing frame body There is no problem due to the difference in coefficients, and the electrical characteristics of the reinforcing frame do not become a problem.

And during molding of the gasket using a die, the reinforcing frame body, with respect to the thickness direction of the gasket molding cavity in advance by the elastic projections made of rubber-like elastic material formed integrally on both surfaces of the reinforcing frame member Therefore, the displacement and deformation of the reinforcing frame due to the injection pressure of the liquid rubber into the gasket molding cavity are suppressed, and a high-quality product can be obtained , and the elastic protrusion is used for gasket molding. The liquid rubber is hardened in the cavity and is embedded and integrated in a gasket that is molded to become a part of this gasket.

The best mode for carrying out the present invention will be described below with reference to the drawings. First, FIG. 1 is a partial cross-sectional view showing a fuel cell gasket integrated part manufactured by the method of manufacturing a fuel cell gasket integrated part according to the present invention. In the following drawings, the right side in the figure is the outer peripheral side and the left side is the inner peripheral side.

In the fuel cell gasket-integrated part shown in FIG. 1, reference numeral 1 is a power generation body of a fuel cell, which is provided on an electrolyte membrane 11, an anode GDL 12 provided on one surface thereof, and the other surface. It consists of cathode GDL13. The anode GDL12 and the cathode GDL13 are gas diffusion electrode layers in which a catalyst electrode layer made of platinum or the like is integrally formed on a porous GDL made of carbon fiber or the like, and corresponds to the GDL according to claim 1 ; Each of the catalyst electrode layers is brought into close contact with the electrolyte membrane 11, and the GDL is brought into contact with the separator in the fuel cell.

  A reinforcing frame 2 is spaced apart from the outer periphery of the power generator 1. The reinforcing frame 2 is embedded in a gasket 3 formed of a rubber-like elastic material having a low hardness and reinforces the gasket 3. The material of the reinforcing frame 2 is the molding temperature (100 of the rubber-like elastic material described above). A synthetic resin film such as PI (polyimide), PEN (polyethylene naphthalate) or PET (polyethylene terephthalate) having heat resistance enough to withstand (˜150 ° C.), or a thin steel plate (SUS) can be used.

  The gasket 3 has a plate-like base 31 joined to the reinforcing frame 2 so as to cover the whole, and a seal lip that protrudes in a mountain shape from both sides in the thickness direction and is brought into close contact with a separator (not shown) in an appropriate compressed state. 32, 33. In the gasket 3, a part of the rubber-like elastic material in the inner peripheral portion of the plate-like base portion 31 is impregnated in the outer peripheral portions of the anode GDL 12 and the cathode GDL 13 of the power generator 1, and the rubber-impregnated portions 12 a and 13 a. Thus, the power generator 1 (the anode GDL12 and the cathode GDL13) is integrated.

  The fuel cell gasket-integrated part having the above configuration constitutes a fuel cell together with a separator (not shown) stacked on both sides in the thickness direction, and a large number of these fuel cells are stacked to form a fuel cell stack. . In each fuel cell, fuel gas (hydrogen) is supplied to the gas flow path formed between the anode GDL12 on one side of the power generator 1 and the separator facing the power G1, and the cathode GDL13 on the other side An oxidizing gas (oxygen) is supplied to the gas flow path formed between the separators facing each other. On the anode side to which the fuel gas is supplied, a reaction for decomposing hydrogen molecules into hydrogen ions and electrons is performed. On the cathode side to which the oxidizing gas is supplied, a reaction for generating water by oxygen, hydrogen ions and electrons is performed. This is done to generate an electromotive force.

  1, the fuel cell gasket-integrated component of FIG. 1 seals the fuel gas, the oxidizing gas, the water generated by the electrochemical reaction in the power generator 1, the excess air, etc. Since the gasket 3 for this purpose is integrated with the power generator 1 (the anode GDL 12 and the cathode GDL 13), the assembly of the fuel cell stack can be simplified.

  Further, in order to reinforce the low-hardness gasket 3, the reinforcement frame 2 embedded and integrated in the gasket 3 is separated from the power generation body 1, and the gasket between the reinforcement frame 2 and the power generation body 1 is a gasket. 3 is insulated through a rubber-like elastic material, and therefore, the reinforcing frame 2 is not only a synthetic resin film but also a conductive metal plate such as a thin steel plate (SUS). There is no problem using it. In addition, since the strain due to the difference in the linear expansion coefficient between the power generation body 1 and the reinforcing frame 2 is absorbed by the rubber-like elastic material interposed between them, the interface peeling between the bonding surfaces of the gasket 3 and the reinforcing frame 2 is also caused. Does not occur. Therefore, the degree of freedom in selecting the material of the reinforcing frame 2 is expanded.

  2, 3 and 4 show a method for manufacturing the fuel cell gasket-integrated part of FIG. Among these, FIG. 2 is a partial cross-sectional view showing a state in which the elastic protrusions 4 are integrally formed on both surfaces of the reinforcing frame 2.

  That is, as shown in FIG. 2, a silk screen printing method and a dispenser method are performed by using low viscosity liquid rubber A on both sides of the reinforcing frame 2 made of the above-described synthetic resin film or thin metal plate. Alternatively, the intermittent elastic protrusions 4 made of a rubber-like elastic material are formed at predetermined intervals by a blade method. In this case, as the liquid rubber A, a material that exhibits adhesiveness to the reinforcing frame 2 by curing is used. If not, an adhesive may be applied to the reinforcing frame 2 in advance. Examples of the material used for the liquid rubber A include liquid EPDM, liquid fluororubber, liquid silicone rubber, liquid acrylic rubber, and the like. Among these, the liquid rubber exhibiting adhesiveness to the reinforcing frame 2 is liquid. Silicone rubber (for example, selective adhesive liquid silicone rubber X-34 series: Shin-Etsu Chemical), liquid fluoro rubber (for example, self-adhesive liquid fluoro rubber SIFEL 600 series: Shin-Etsu Chemical), or liquid EPDM can be used.

  Further, if necessary, an adhesive layer is provided on both surfaces of the reinforcing frame 2 by, for example, a silk screen printing method, and rubber ink (unvulcanized rubber compound is dispersed in an organic solvent) on the adhesive layer. The elastic protrusion 4 can also be formed by applying the material by a silk screen printing method or the like, and drying and vulcanizing it. The protruding height h of the elastic protrusion 4 from the reinforcing frame 2 is slightly larger than the rubber thickness t of the plate-like base 31 of the gasket 3 shown in FIG.

  Next, FIG. 3 is a partial cross-sectional view showing a state in which the power generation body and the reinforcing frame are set in the mold, and FIG. 4 is a diagram in which the mold is filled with liquid rubber and the gasket is used as the power generation body and the reinforcement frame. It is a fragmentary sectional view which shows the process in which it shape | molds integrally.

  In FIG. 3, reference numeral 5 is a mold including an upper mold 51 and a lower mold 52. Between the opposing surfaces of the upper mold 51 and the lower mold 52 that are in contact with each other, clamping surfaces 51a and 52a that can clamp the power generation body 1 by clamping are formed, and an outer peripheral portion of the power generation body 1 is formed on the outer peripheral side. Gasket forming cavities 53 are defined between them. In the upper mold 51, a gate 54 for filling the gasket molding cavity 53 with liquid rubber is opened toward the base molding portion 531 of the gasket molding cavity 53.

  The gasket-forming cavity 53 has a shape corresponding to the gasket 3 in the fuel cell gasket-integrated part of FIG. 1, that is, a flat base-forming portion 531 having a shape corresponding to the plate-like base portion 31 of the gasket 3, and a gasket. 3 seal lips 32, 33 and seal lip molding portions 532, 533 having a corresponding shape. At the time of clamping, the outer peripheral portion of the power generator 1 (the anode GDL 12 and the cathode GDL 13) that protrudes from between the clamping surfaces 51a and 52a to the outer peripheral side is the upper die 51 and the lower die in the base molding portion 531 of the gasket molding cavity 53. It faces the inner surface of 52 via a slight gap G1, G2.

  When the fuel cell gasket integrated part of FIG. 1 is integrally formed by the above-described mold 5, first, the electrolyte membrane 11 and the anode GDL 12 and the cathode GDL 13 laminated on both surfaces thereof are sandwiched on the sandwiching surface 52 a of the lower die 52. A reinforcing frame 2 having elastic protrusions 4 formed on both sides by a process shown in FIG. 2 is positioned and set on the outer peripheral side of the power generating body 1 at the position where the gasket forming cavity 53 is formed by clamping. The positioning is set in a state of being separated from the power generator 1. In this state, by clamping the upper mold 51 and the lower mold 52, the power generator 1 is clamped between the clamping surfaces 51a and 52a, and the outer peripheral portion of the power generator 1, the upper mold 51, and the lower mold The reinforcing frame 2 is positioned and fixed in a gasket forming cavity 53 defined between the inner surface of the gasket 52.

  As described above, the protrusion height h (see FIG. 2) of the elastic protrusion 4 formed in advance on the reinforcing frame 2 is determined from the rubber thickness t of the plate-like base 31 of the gasket 3 shown in FIG. 3 is slightly larger than the dimension t ′ in the thickness direction of the base molding portion 531 of the gasket molding cavity 53 shown in FIG. 3, so that each elastic protrusion 4 is appropriately It contacts the inner surfaces of the upper mold 51 and the lower mold 52 in a compressed state. For this reason, the reinforcing frame 2 is supported in a state of being positioned via the elastic protrusions 4 on both sides at the intermediate position in the thickness direction in the base molding portion 531 of the gasket molding cavity 53.

  Next, as shown in FIG. 4, the liquid rubber B is injected and filled into the gasket molding cavity 53 through the gate 54 provided in the upper mold 51. As the liquid rubber B, a material that exhibits adhesiveness to the reinforcing frame 2 by curing is used. Otherwise, the reinforcing frame 2 is attached to the reinforcing frame 2 before setting the reinforcing frame 2 in the mold 5. An adhesive may be applied in advance. Examples of the liquid rubber B include liquid EPDM, liquid fluororubber, liquid silicone rubber, liquid acrylic rubber, and the like. Among these, the liquid rubber exhibiting adhesiveness to the reinforcing frame 2 includes liquid silicone rubber (for example, Selective adhesive liquid silicone rubber X-34 series: Shin-Etsu Chemical Co., Ltd., liquid fluoro rubber (for example, self-adhesive liquid fluoro rubber SIFEL 600 series: Shin-Etsu Chemical Co., Ltd.), or liquid EPDM can be used.

  The reinforcing frame 2 in the gasket molding cavity 53 is supported at the intermediate position in the thickness direction of the base molding portion 531 by the elastic projections 4 integrally provided at predetermined intervals on both surfaces. Deflection and displacement due to the fluid pressure of the flowing liquid rubber B are effectively suppressed. Further, since the elastic protrusion 4 is formed intermittently, the liquid rubber B flows into the entire area of the molding cavity 53 and is shaped.

  Since the liquid rubber B flowing from the gate 54 has a low viscosity, a part of the liquid rubber B is directly injected from the end face to the outer peripheral portions of the anode GDL12 and the cathode GDL13 in the power generation body 1 and the gaps G1 and G2 shown in FIG. Impregnated through. The liquid rubber B is cured in the gasket-forming cavity 53 to become a gasket 3 having a shape corresponding to the shape of the inner surface, and is bonded and integrated in a state where the reinforcing frame 2 is embedded. The inner peripheral portion is integrated with the power generator 1 via the cured portions (rubber-impregnated portions 12a and 13a) in a state where the outer peripheral portions of the anode GDL 12 and the cathode GDL 13 of the power generator 1 are impregnated. Further, the elastic protrusion 4 formed in advance on the reinforcing frame 2 is joined and integrated with the liquid rubber B to be cured, and becomes a part of the gasket 3.

  And as mentioned above, since the bending and displacement of the reinforcing frame 2 in the molding process of the gasket 3 are effectively suppressed, the rubber thicknesses on both sides in the thickness direction of the reinforcing frame 2 become substantially equal and stable. The gasket 3 that exhibits sealing properties can be molded.

  As described above, the elastic protrusions 4 integrally provided in advance on both surfaces of the reinforcing frame 2 at a predetermined interval are appropriately compressed in the clamping state shown in FIG. When the upper mold 51 and the lower mold 52 of the mold 5 are opened later, the portion 4 ′ corresponding to the elastic protrusion 4 in the plate-like base portion 31 of the gasket 3 tends to rise due to the compression reaction force. And, when the fuel cell gasket integrated part obtained as described above is laminated together with a separator (not shown) and assembled as a fuel cell stack, when the raised portion due to the portion 4 ′ comes into contact with the separator, As a result, the resilience characteristics of the seal lips 32 and 33 may be impaired.

  Therefore, in the state assembled as a fuel cell stack, even when the plate clearance of each cell is the assumed minimum value, the protruding portion due to the elastic protrusion corresponding portion 4 ′ of the plate-like base portion 31 of the gasket 3 is not formed. The molding height h of the elastic protrusion 4 shown in FIG. 2 is specified so as not to contact the separator. For the same reason, the liquid rubber A used for molding the elastic protrusion 4 is cured. It is desirable that the product has a lower hardness than the cured product of the liquid rubber B injected into the cavity 53.

  Further, the formation interval of the elastic protrusions 4 is desirably about 10 to 20 mm from the viewpoint of effectively preventing bending and displacement due to the fluid pressure of the liquid rubber B or the like.

It is a fragmentary sectional view which shows the gasket integrated part for fuel cells manufactured by the manufacturing method of the gasket integrated part for fuel cells which concerns on this invention. FIG. 2 is a partial cross-sectional view showing a state in which elastic protrusions are integrally formed on both surfaces of a reinforcing frame body in the method for producing the fuel cell gasket integrated part of FIG. FIG. 2 is a partial cross-sectional view showing a state in which a power generator and a reinforcing frame are set in a mold in the method for manufacturing the fuel cell gasket-integrated part of FIG. FIG. 2 is a partial cross-sectional view illustrating a process of filling a gasket with liquid rubber and integrally molding a gasket with a power generator and a reinforcing frame in the method for manufacturing the fuel cell gasket-integrated part of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power generation body 11 Electrolyte membrane 12 Anode GDL (GDL)
12a, 13a Rubber impregnated part 13 Cathode GDL
2 Reinforcement frame 3 Gasket 4 Elastic protrusion 5 Mold 51 Upper mold 51a, 52a Holding surface 52 Lower mold 53 Gasket molding cavity 54 Gate A, B Liquid rubber G1, G2 Gap

Claims (1)

The power generation body (1) including the GDL (12, 13) on both sides in the thickness direction is sandwiched in the mold (5), and between the outer periphery of the power generation body (1) and the inner surface of the mold (5). The reinforcing frame (2) is integrally formed in advance on both surfaces of the reinforcing frame (2) in a state where the reinforcing frame (2) is separated from the power generation body (1) in the gasket forming cavity (53) defined in FIG. It is positioned and fixed through an elastic protrusion (4) made of a rubber-like elastic material, and the gasket molding cavity (53) is filled with liquid rubber (B), and a part of it is filled with the GDL (12, 13). The liquid rubber (B) is hardened and adhered to the reinforcing frame (2).

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