JP7022583B2 - Fuel cell and its manufacturing method - Google Patents

Description

The present invention relates to a fuel cell including an electrolyte membrane and a rubber gasket adhered to a separator, and a method for manufacturing the same.

The fuel cell has a stack structure in which a large number of cells are stacked. The cell includes an electrode member having an electrolyte membrane and an electrode, a separator sandwiching the electrode member, and a rubber gasket for sealing around the electrode member and between adjacent separators.

The rubber gasket that seals the electrode member is adhered to both the electrolyte membrane and the separator. As the bonding method, a method of heating a rubber composition for forming a rubber gasket in contact with a mating member and bonding the rubber at the same time as cross-linking (thermal cross-linking bonding method), or a rubber produced by heat-cross-linking. A method of post-bonding a gasket and a mating member with an adhesive or the like is known (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2017-65042 International Publication No. 2013/147020

In the thermal cross-linking bonding method, a cross-linking agent such as sulfur or an organic peroxide is mixed with the raw rubber to prepare a rubber composition, which is heated to a temperature at which the cross-linking agent reacts to cross-link. Since most of the separators are made of metal, there is little effect even if the separators are exposed to high temperatures during cross-linking and bonding. However, since the electrolyte membrane is a polymer membrane, if the electrolyte membrane is exposed to a high temperature during cross-linking and adhesion, it is susceptible to heat damage and may deteriorate.

In addition, the electrolyte membrane moves or stretches due to fluctuations in gas pressure or vibration from the outside. Therefore, as described in Patent Document 2, when the rubber gasket and the electrolyte membrane are adhered with an adhesive, the adhesive layer in contact with the electrolyte membrane can follow the movement and deformation of the electrolyte membrane. Flexibility is required. On the other hand, the adhesive layer in contact with the separator is not required to have the same degree of flexibility.

As described above, in the fuel cell, it is desirable to select the optimum bonding method and adhesive according to the member to be bonded. However, at present, the same adhesive is used for both the electrolyte membrane and the separator, and the adhesive is not used properly depending on the member to be bonded.

The present invention has been made in view of such circumstances, and by using an adhesive according to the member to be bonded, a fuel cell having good adhesiveness of a rubber gasket to both an electrolyte membrane and a separator. An object of the present invention is to provide a cell and a method for manufacturing the cell.

(1) In order to solve the above problems, the fuel cell of the present invention includes an electrolyte membrane, a separator, and a rubber gasket that is adhered to both the electrolyte membrane and the separator and seals the peripheral portion of the electrolyte membrane. A first adhesive layer is arranged between the rubber gasket and the separator, and a silane cup is placed between the rubber gasket and the electrolyte membrane in order from the rubber gasket side. It is characterized in that a ring agent layer and a second adhesive layer different from the first adhesive layer are arranged.

(2) In order to solve the above problems, the method for manufacturing a fuel cell of the present invention comprises an electrolyte membrane, a separator, and a rubber that is adhered to both the electrolyte membrane and the separator and seals the peripheral edge of the electrolyte membrane. A method for manufacturing a fuel cell cell including a gasket, wherein a separator bonding step of bonding the rubber gasket and the separator with a first adhesive, and a silane coupling agent of the rubber gasket and the electrolyte film are used. It is characterized by having an electrolyte film bonding step of arranging on the rubber gasket side and bonding with the silane coupling agent and a second adhesive different from the first adhesive layer.

(1) In the fuel cell of the present invention, different adhesive layers are arranged between the rubber gasket and the separator, and between the rubber gasket and the electrolyte membrane. That is, the separator and the electrolyte membrane are adhered to the rubber gasket with different adhesives. As a result, the optimum adhesive can be selected according to the mating member in consideration of the characteristics of the separator and the electrolyte membrane (hereinafter, may be collectively referred to as "mating member") and the characteristics required for each. It is possible to solve the problem caused by using the same adhesive as in the conventional case. For example, by using an adhesive having a low reaction temperature only for the electrolyte membrane, deterioration of the electrolyte membrane due to heat damage can be suppressed. Further, by using a flexible adhesive only for the electrolyte membrane, it is possible to improve the followability to the electrolyte membrane.

In the fuel cell of the present invention, a silane coupling agent layer and a second adhesive layer are arranged between the rubber gasket and the electrolyte membrane. That is, the rubber gasket and the electrolyte membrane are adhered using two kinds of adhesives. By arranging the silane coupling agent layer on the rubber gasket side, the adhesive strength between the rubber gasket and the second adhesive layer is increased, and the adhesiveness between the rubber gasket and the electrolyte film can be improved. Therefore, even if sufficient adhesive strength cannot be obtained from either the silane coupling agent layer or the second adhesive layer, the desired adhesiveness can be ensured by laminating the two layers. For example, some adhesives do not easily undergo a chemical reaction and do not exhibit sufficient adhesive force unless they are heated to a high temperature of about 150 ° C. However, by laminating the two layers of the silane coupling agent layer and the second adhesive layer, it is possible to secure the desired adhesiveness without treatment at a high temperature. This aspect is effective in suppressing deterioration of the electrolyte membrane because the electrolyte membrane does not need to be exposed to a high temperature.

(2) In the method for manufacturing a fuel cell of the present invention, the separator and the electrolyte membrane are bonded to the rubber gasket with different adhesives. This makes it possible to select the optimum adhesive according to the mating member in consideration of the characteristics of the separator and the electrolyte membrane and the characteristics required for each, and the problem of using the same adhesive as in the past. Can be resolved. For example, by using an adhesive having a low reaction temperature only for the electrolyte membrane, deterioration of the electrolyte membrane due to heat damage can be suppressed. Further, by using a flexible adhesive only for the electrolyte membrane, it is possible to improve the followability to the electrolyte membrane.

In the method for manufacturing a fuel cell of the present invention, the rubber gasket and the electrolyte membrane are bonded to each other by using two kinds of adhesives, a silane coupling agent and a second adhesive. By arranging the silane coupling agent on the rubber gasket side, the adhesive strength between the rubber gasket and the second adhesive is increased, and the adhesiveness between the rubber gasket and the electrolyte film can be improved. Therefore, even if sufficient adhesive strength cannot be obtained with either the silane coupling agent or the second adhesive, the desired adhesiveness can be ensured by using both of them. As described above, even when an adhesive that does not exhibit sufficient adhesive strength unless heated to a high temperature of about 150 ° C. is used, it is not treated under high temperature by using a silane coupling agent and a second adhesive together. However, it is possible to secure the desired adhesiveness. In this case, since the electrolyte membrane is not exposed to high temperature, it is effective in suppressing the deterioration of the electrolyte membrane.

It is sectional drawing which shows one Embodiment of the fuel cell of this invention.

<Fuel cell>
In the fuel cell of the present invention, a first adhesive layer is arranged between the rubber gasket and the separator, and between the rubber gasket and the electrolyte membrane, a silane coupling agent layer and a silane coupling agent layer are arranged in order from the rubber gasket side. A second adhesive layer different from the first adhesive layer is arranged.

[Rubber gasket]
The rubber gasket is adhered to both the electrolyte membrane and the separator to seal the peripheral edge of the electrolyte membrane. The rubber gasket is manufactured from a rubber composition containing rubber or a thermoplastic elastomer (rubber component). Among these, as rubber, ethylene-propylene-diene rubber (EPDM), silicone rubber, fluororubber, butyl rubber (IIR), ethylene-propylene rubber (EPM), acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber ( H-NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR) and the like. In addition to the rubber component, the rubber composition may contain a cross-linking agent, a cross-linking accelerator, a processing aid, a softening agent, a reinforcing material, and the like.

If the rubber composition contains a cross-linking agent or a cross-linking accelerator, it decomposes during the reaction and the decomposed product bleeds out to the surface of the rubber gasket. In addition, the mold release agent applied to the mold used at the time of crosslinking and the contaminants deposited on the mold may be transferred to the rubber gasket. For this reason, in the conventional method of adhering the crosslinked rubber gasket to the mating member using an adhesive, the surface of the rubber gasket is cleaned before adhering to remove components that adversely affect the adhesiveness. Further, a mold or an oven is used for thermal cross-linking. In the former, heat is transferred from the mold, and in the latter, heat is transferred from an atmosphere such as air to apply heat to the rubber composition. In order to improve the production efficiency, it is effective to shorten the crosslinking time, but it is not easy in the thermal crosslinking because it depends on the thermal conductivity of the heat transfer path. Further, there is also a problem that a unique odor is generated at the time of cross-linking due to decomposition of the cross-linking agent or the like contained in the rubber composition.

Therefore, in order to solve various problems in thermal cross-linking, it is desirable that the rubber gasket is a cross-linked product in which the rubber composition is cross-linked by irradiation with active energy rays. When the active energy ray is used, it is not necessary to add a cross-linking agent or the like to the rubber composition, and it is not necessary to heat the rubber composition. Therefore, the step of cleaning the rubber gasket before bonding can be omitted, and the problem that odor is generated at the time of crosslinking can be solved. Further, the use of active energy rays has the advantages that the cross-linking time is short and the dimensional change is small.

[Separator]
The material and shape of the separator are not particularly limited. One example is a rectangular thin plate-shaped separator made of metal such as stainless steel or titanium.

[Electrolyte membrane]
Examples of the electrolyte membrane include polymer membranes such as all-fluorine-based sulfonic acid membranes, all-fluorine-based phosphonic acid membranes, all-fluorine-based carboxylic acid membranes, and hydrocarbon-based membranes. The electrolyte membrane has a rectangular thin film shape, and together with the anode catalyst layer and the cathode catalyst layer arranged on both sides thereof, constitutes a membrane electrode assembly (MEA). The anode catalyst layer and the cathode catalyst layer include, for example, carbon particles carrying platinum.

[First adhesive layer]
The first adhesive layer is arranged between the rubber gasket and the separator. The first adhesive layer is a layer formed by curing the first adhesive. The first adhesive is not particularly limited as long as the rubber gasket and the separator can be adhered to each other. For example, polyolefin adhesives, chlorine rubber adhesives, acrylic adhesives, epoxy adhesives, polyurethane adhesives, nitrile rubber adhesives, vinyl chloride adhesives, vinyl acetate adhesives, polyester adhesives. , Phenolic adhesives, silicone adhesives and the like. Above all, it is desirable to use a thermoplastic resin-based adhesive as the first adhesive from the viewpoint that it can be melted by heating and the adhesion to the member to be bonded can be improved. In order to further improve the adhesiveness, it is desirable to use an acid-modified thermoplastic resin-based adhesive. From the above, it is preferable that the first adhesive layer is made of a thermoplastic resin-based adhesive, and further preferably an acid-modified thermoplastic resin-based adhesive.

[Second adhesive layer]
The second adhesive layer is arranged on the electrolyte membrane side between the rubber gasket and the electrolyte membrane. The second adhesive layer is a layer formed by curing a second adhesive different from the first adhesive. The second adhesive may be appropriately selected depending on the material of the electrolyte membrane, and it is desirable that the second adhesive does not contain an ionic component or a metal component.

As described above, the electrolyte membrane moves or stretches due to fluctuations in gas pressure, vibrations from the outside, and the like. Therefore, it is desirable that the second adhesive layer is flexible so as to be able to follow the movement and deformation of the electrolyte membrane. From this point of view, it is desirable that the elastic modulus of the second adhesive layer is smaller than the elastic modulus of the first adhesive layer. For example, the elastic modulus of the second adhesive layer is preferably 100 MPa or less. It is more preferable that it is 50 MPa or less, more preferably 10 MPa or less. Examples of the second adhesive having a relatively small elastic modulus include a silicone resin-based adhesive and an acrylic resin-based adhesive. In order to further improve the adhesiveness, it is desirable to use a modified silicone resin-based adhesive. From the above, it is preferable that the second adhesive layer is made of a silicone resin-based adhesive or an acrylic resin-based adhesive, and further is made of a modified silicone resin-based adhesive. Further, if the second adhesive is an adhesive that cures at a relatively low temperature, deterioration of the electrolyte due to heat damage can be suppressed. Further, if the adhesive is a room temperature curing type, it does not need to be heated at the time of bonding, so that there is no possibility that the electrolyte membrane is deteriorated due to heat damage.

[Silane coupling agent layer]
The silane coupling agent layer is arranged on the rubber gasket side between the rubber gasket and the electrolyte membrane. The silane coupling agent layer serves to improve the adhesive force to the rubber gasket.

[Example of fuel cell configuration]
FIG. 1 shows a cross-sectional view of an embodiment of the fuel cell of the present invention. As shown in FIG. 1, the fuel cell 1 includes an electrode member 20, separators 30a and 30b, rubber gaskets 40a and 40b, a first adhesive layer 50, a silane coupling agent layer 51, and a second adhesive layer. 52 and.

The electrode member 20 has a MEA 21 and gas diffusion layers 22a and 22b. The MEA 21 has an electrolyte membrane 23. The electrolyte membrane 23 is an all-fluorine-based sulfonic acid membrane and has a rectangular thin film shape. Catalyst layers are arranged on both the upper and lower surfaces of the electrolyte membrane 23. The catalyst layer contains carbon particles carrying platinum. Both the gas diffusion layers 22a and 22b are made of sintered foam metal and have a rectangular thin plate shape. The gas diffusion layer 22a is laminated on the upper surface of the MEA 21, and the gas diffusion layer 22b is laminated on the lower surface of the MEA 21.

The separators 30a and 30b are both made of titanium and have a rectangular thin plate shape. The separator 30a is laminated on the upper surface of the gas diffusion layer 22a. The separator 30b is laminated on the lower surface of the gas diffusion layer 22b.

Both the rubber gaskets 40a and 40b are made of a crosslinked product obtained by electron beam cross-linking of a rubber composition containing EPDM as a rubber component, and have a rectangular frame shape. The first adhesive layer 50 is arranged between the rubber gasket 40a and the separator 30a. The first adhesive layer 50 is made of an acid-modified thermoplastic resin-based adhesive. The rubber gasket 40a is adhered to the separator 30a via the first adhesive layer 50. Similarly, the first adhesive layer 50 is arranged between the rubber gasket 40b and the separator 30b. The rubber gasket 40b is adhered to the separator 30b via the first adhesive layer 50.

The silane coupling agent layer 51 and the second adhesive layer 52 are arranged between the rubber gasket 40a and the electrolyte membrane 23. The silane coupling agent layer 51 is arranged on the rubber gasket 40a side. The second adhesive layer 52 is arranged on the side of the electrolyte membrane 23. The second adhesive layer 52 is made of a modified silicone resin-based adhesive. The rubber gasket 40a is adhered to the electrolyte membrane 23 via the silane coupling agent layer 51 and the second adhesive layer 52. Similarly, the silane coupling agent layer 51 and the second adhesive layer 52 are arranged between the rubber gasket 40b and the electrolyte membrane 23. The silane coupling agent layer 51 is arranged on the rubber gasket 40b side. The second adhesive layer 52 is arranged on the side of the electrolyte membrane 23. The rubber gasket 40b is adhered to the electrolyte membrane 23 via the silane coupling agent layer 51 and the second adhesive layer 52. In this way, the rubber gaskets 40a and 40b are sealed by blocking the electrode member 20 from the outside.

The configuration of the fuel cell of the present invention is not limited to this embodiment. In this embodiment, the rubber gasket is composed of two members divided into upper and lower parts, but the rubber gasket may be a single member. Further, the fuel cell of the present invention may have other components. For example, gas flow path layers made of a porous material may be arranged on both sides of the gas diffusion layer in the stacking direction.

<Manufacturing method of fuel cell>
The method for manufacturing a fuel cell of the present invention includes a separator bonding step and an electrolyte membrane bonding step. Here, the separator bonding step and the electrolyte membrane bonding step are in no particular order, and either step may be performed first or both steps may be performed at the same time. Hereinafter, each step will be described.

[Separator bonding process]
This step is a step of adhering the rubber gasket and the separator with the first adhesive. The rubber gasket, the separator, and the first adhesive are as described in the embodiment of the fuel cell of the present invention. The first adhesive may be placed on at least one adhesive surface of the rubber gasket and the separator. If the first adhesive is liquid, it may be applied with a spray, dispenser, or the like. If the first adhesive is a solid such as a film, it may be placed as it is. With the first adhesive interposed between the rubber gasket and the separator, the adhesive may be adhered by applying pressure at a predetermined temperature and if necessary.

For example, the first adhesive is placed on the adhesive surface of the frame-shaped rubber gasket with the separator, the separator is placed on it, and then the adhesive is pressed and bonded at a temperature of about 120 to 200 ° C. for several seconds to several tens of seconds. be able to. In this case, if the first adhesive is preheated and softened, the compatibility with the rubber gasket is improved, the adhesiveness is improved, and the time required for adhesion can be shortened.

[Electrolyte membrane adhesion process]
This step is a step of arranging the silane coupling agent on the rubber gasket side and adhering the rubber gasket and the electrolyte film with a silane coupling agent and a second adhesive different from the first adhesive. The rubber gasket, the electrolyte membrane, the silane coupling agent, and the second adhesive are as described in the embodiment of the fuel cell of the present invention. From the viewpoint of softening the second adhesive layer in contact with the electrolyte membrane, it is desirable that the elastic modulus of the second adhesive is smaller than the elastic modulus of the first adhesive.

The silane coupling agent may be applied to the adhesive surface of the rubber gasket with the electrolyte membrane by a spray, a dispenser or the like. The second adhesive may be placed on top of the silane coupling agent or may be placed on the electrolyte membrane side. If the second adhesive is liquid, it may be applied with a spray, dispenser, or the like. If the second adhesive is a solid such as a film, it may be placed as it is.

A silane coupling agent and a second adhesive may be interposed between the rubber gasket and the electrolyte membrane in this order, and the adhesive may be adhered by applying pressure at a predetermined temperature and if necessary. From the viewpoint of avoiding thermal damage of the electrolyte membrane and suppressing deterioration, it is desirable to perform the adhesion in this step at 50 ° C. or lower. For example, a silane coupling agent is applied to the adhesive surface of the frame-shaped rubber gasket with the electrolyte membrane, a second adhesive is applied on the surface, and then the electrolyte membrane is overlapped and held at room temperature for several seconds to several tens of seconds. And glue it.

Focusing on the fact that the rubber gasket and the electrolyte membrane are bonded at a low temperature, the method for manufacturing the fuel cell is to be applied between the rubber gasket and the electrolyte membrane, regardless of the difference between the adhesive used to bond the separator and the adhesive. A silane coupling agent and another adhesive may be arranged in this order from the rubber gasket side so as to have a step of adhering the rubber gasket and the electrolyte film at 50 ° C. or lower. can.

[Rubber gasket manufacturing process]
As described above, in order to solve various problems that occur when the rubber gasket is manufactured by thermal cross-linking, it is desirable to manufacture the rubber gasket by irradiation with active energy rays. For example, in the method for manufacturing a fuel cell of the present invention, a rubber gasket manufacturing step of cross-linking an uncrosslinked rubber member by irradiating an active energy ray before a separator bonding step and an electrolyte film bonding step to manufacture a rubber gasket. Can be configured to have.

The uncrosslinked rubber member is a member obtained by molding a rubber composition. When the active energy ray is used, it is not necessary to add a cross-linking agent or the like to the rubber composition, and it is not necessary to heat the rubber composition. Therefore, the step of cleaning the rubber gasket before bonding can be omitted, and the problem that odor is generated at the time of crosslinking can be solved. Further, the use of active energy rays has the advantages that the cross-linking time is short and the dimensional change is small. Examples of the active energy ray include an electron beam and ultraviolet rays.

A test piece was manufactured from the materials used for the electrolyte membrane, separator, and rubber gasket of the fuel cell, and the adhesiveness between the members was evaluated.

<Manufacturing of test pieces with separators adhered>
A test piece was manufactured according to the separator bonding step in the method for manufacturing a fuel cell of the present invention. First, a rubber composition consisting of 100 parts by mass of EPDM, 50 parts by mass of carbon black, and 20 parts by mass of paraffin-based process oil (“Diana (registered trademark) process oil PW380” manufactured by Idemitsu Kosan Co., Ltd.) is extruded into a sheet. The uncrosslinked rubber member (thickness 1 mm) was manufactured. Next, the uncrosslinked rubber member was irradiated with an electron beam (absorbed dose 200 kGy) to produce a crosslinked rubber sheet. Subsequently, Adhesive A (maleic anhydride-modified polyolefin resin film (“Admer (registered trademark) NF518” manufactured by Mitsui Chemicals, Inc., thickness 0.05 mm) was placed on one surface of the crosslinked rubber sheet), and then titanium. A thin plate (thickness 0.1 mm) made of the same material was laminated on the adhesive A to produce a laminated body. The manufactured laminated body was sandwiched between a pair of metal plates maintained at a temperature of 180 ° C., and the surface pressure was increased. It was held for 10 seconds while being pressurized at 1 MPa. Then, it was left at room temperature for one day. In this way, a test piece in which the crosslinked rubber sheet and the thin plate made of titanium were adhered was produced. The size is 5 mm in width and 40 mm in length. In this embodiment, the thin plate made of titanium corresponds to a separator. Therefore, in the following, for convenience, the thin plate made of titanium is referred to as a separator. The adhesive A is the first. (1) Included in the concept of adhesive. Table 1 shows the configuration of the test piece.

<Manufacturing of test pieces with electrolyte membrane adhered>
[Example 1]
A test piece was manufactured according to the electrolyte membrane bonding step in the method for manufacturing a fuel cell of the present invention. First, a crosslinked rubber sheet used when manufacturing a test piece to which a separator was adhered was prepared. Next, a silane coupling agent was applied to one surface of the crosslinked rubber sheet, and an adhesive other than the silane coupling agent was further applied thereto and dried. Subsequently, an electrolyte membrane (all-fluorine-based sulfonic acid membrane, "Nafion" manufactured by DuPont (registered trademark), thickness 20 μm) was layered on the adhesive to produce a laminate. The produced laminate was sandwiched between a pair of metal plates maintained at a temperature of 25 ° C. and held for 10 seconds while being pressurized at a surface pressure of 1 MPa. Then, it was left at room temperature for one day. In this way, a test piece in which the crosslinked rubber sheet and the electrolyte membrane were adhered was manufactured. The size of the adhesive surface in the test piece is 10 mm in width and 40 mm in length. The adhesive B described later used in this embodiment is included in the concept of the second adhesive.

[Comparative Example 1]
The test piece was manufactured in the same manner as in Example 1 except that the laminate was manufactured without using any adhesive.

[Comparative Examples 2 and 3]
A test piece was manufactured in the same manner as in Example 1 except that the laminate was manufactured using only one of the silane coupling agent and the adhesive.

[Comparative Examples 4 and 5]
The same as in Example 1 except that the laminate was manufactured using only one of the silane coupling agent and the adhesive, and the temperature (adhesion temperature) of the metal plate was changed to 150 ° C. Manufactured a test piece.

Table 2 shows the configuration of the test piece. The silane coupling agents and adhesives used are as follows.
Silane coupling agent a: "Chemlock (registered trademark) 607" manufactured by Lord Far East.
Adhesive B: Modified silicone resin adhesive (“Super X No. 8008” manufactured by Cemedine Co., Ltd.).

<Measurement method of elastic modulus>
The elastic modulus of the adhesives A and B was measured using a dynamic viscoelasticity measuring device (“Rheogel-E4000F” manufactured by UBM Co., Ltd.). For the measurement, a flat plate-shaped test piece having a width of 5 mm and a length of 30 mm was used. The measurement was performed by sandwiching the test piece between the upper and lower holders and vibrating the lower holder up and down at a frequency of 5 Hz. The amplitude was 0.005 mm and the distance between chucks was 20 mm. Tables 1 and 2 summarize the measurement results of the elastic modulus.

<Evaluation method of adhesiveness>
Each test piece was subjected to a 90 ° peeling test specified in JIS K 6256-2: 2013 to evaluate the adhesiveness of the separator or electrolyte membrane to the crosslinked rubber sheet.

Regarding the adhesiveness of the separator, when the peeling strength obtained by the 90 ° peeling test was 0.3 N / mm or more, the adhesiveness was good (indicated by ◯ in Table 1 above). The adhesiveness of the electrolyte membrane was evaluated based on the adhesive strength index calculated by the following formula (I) from the value of the peeling strength obtained by the 90 ° peeling test. When the adhesive strength index is 100 or more and the electrolyte membrane is not deteriorated, the adhesiveness is good (indicated by a circle in Table 2 above), when the adhesive strength index is less than 100, or when the electrolyte membrane is deteriorated. Was regarded as poor adhesiveness (indicated by a cross in the same table). Tables 1 and 2 summarize the evaluation results of adhesiveness.
Adhesive strength index = (peeling strength of each test piece / peeling strength of the test piece of Comparative Example 4) × 100 ... (I)
<Comprehensive evaluation method>
For the test piece to which the electrolyte film was adhered, the adhesiveness was evaluated well, and the elasticity of the adhesive (second adhesive layer) used was the elasticity of the adhesive A (adhesive to which the separator was adhered, the first adhesive layer). Comprehensive evaluation that it is very suitable when it is smaller than the rate (indicated by ◎ in Table 2 above) and not suitable when the evaluation of adhesiveness is poor (indicated by × in the same table). did. Table 2 summarizes the comprehensive evaluation.

<Evaluation result>
As shown in Table 1, the adhesiveness of the separator was good. Further, as shown in Table 2, in the test piece of Example 1 in which the silane coupling agent and the other adhesive were used in combination, the adhesiveness of the electrolyte membrane was good. On the other hand, in the test pieces of Comparative Examples 1 to 5 in which no adhesive was used or only one of the silane coupling agent and the other adhesive was used, the adhesiveness of the electrolyte membrane was poor. In the test piece of Comparative Example 4 as a standard of adhesive strength, since the adhesive temperature was as high as 150 ° C., the desired peeling strength could be obtained only with the silane coupling agent. However, since the bonding temperature was high, deterioration was observed in the electrolyte membrane. Therefore, the adhesiveness was poor. Further, in the test piece of Comparative Example 5, the peeling strength was small even when the bonding temperature was high, and the electrolyte membrane was also deteriorated.

In the test piece of Example 1, the elastic modulus of the adhesive B (second adhesive layer) is smaller than the elastic modulus of the adhesive A (first adhesive layer) to which the separator is adhered. Therefore, the second adhesive layer in contact with the electrolyte membrane is flexible and has excellent followability to the movement and deformation of the electrolyte membrane. Therefore, the comprehensive evaluation of the test piece of Example 1 resulted in that the adhesive used was very suitable for adhering the electrolyte membrane.

1: Fuel cell, 20: Electrode member, 22a, 22b: Gas diffusion layer, 23: Electrolyte membrane, 30a, 30b: Separator, 40a, 40b: Rubber gasket, 50: First adhesive layer, 51: Silane coupling agent Layer, 52: Second adhesive layer.

Claims (8)

A fuel cell comprising an electrolyte membrane, a separator, and a rubber gasket that is adhered to both the electrolyte membrane and the separator and seals the peripheral edge of the electrolyte membrane.
A first adhesive layer is arranged between the rubber gasket and the separator.
Between the rubber gasket and the electrolyte membrane, a silane coupling agent layer and a second adhesive layer having a lower elastic modulus than the first adhesive layer are arranged in order from the rubber gasket side.
The fuel cell is characterized in that the second adhesive layer is made of a room temperature curable adhesive . The fuel cell according to claim 1, wherein the first adhesive layer is made of a thermoplastic resin adhesive. The fuel cell according to claim 1 or 2 , wherein the second adhesive layer is made of a silicone resin-based adhesive. The fuel cell according to any one of claims 1 to 3 , wherein the rubber gasket is a crosslinked product in which the rubber composition is crosslinked by irradiation with active energy rays. A method for manufacturing a fuel cell, comprising: an electrolyte membrane, a separator, and a rubber gasket that is adhered to both the electrolyte membrane and the separator and seals the peripheral edge of the electrolyte membrane.
A separator bonding step of bonding the rubber gasket and the separator with a first adhesive, and
The rubber gasket and the electrolyte film are placed at 50 ° C. by arranging the silane coupling agent on the rubber gasket side and using the silane coupling agent and the second adhesive having a lower elastic modulus than the first adhesive. The electrolyte film bonding process to be bonded below and
A method for manufacturing a fuel cell, which comprises. The method for manufacturing a fuel cell according to claim 5 , wherein in the electrolyte membrane bonding step, the rubber gasket and the electrolyte membrane are bonded without heating. 5. In the electrolyte membrane bonding step, the silane coupling agent is applied to the rubber gasket, the second adhesive is applied to the surface of the silane coupling agent , and then the electrolyte membrane is laminated and bonded. Alternatively, the method for manufacturing a fuel cell according to claim 6 . Claim 5 to claim 7 , further comprising a rubber gasket manufacturing step of cross-linking an uncrosslinked rubber member by irradiating an active energy ray to manufacture the rubber gasket before the separator bonding step and the electrolyte film bonding step. The method for manufacturing a fuel cell according to any one.

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