JP2007278366A - Gasket molding method and gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasket molding method for improving the quality of a gasket while improving working efficiency, and to provide the gasket. <P>SOLUTION: The method comprises a step of using screen printing for printing on a base (a separator 10 of a fuel cell, e.g.) self-adhesive liquid rubber as a raw material for the gasket 30, and a step of hardening the printed liquid rubber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gasket molding method and a gasket for molding a gasket on a substrate.

  In order to facilitate the positioning of the gasket to the mounting part and to improve the work efficiency by omitting the gasket mounting work, a technique for fixing the gasket to the member to which the gasket is to be adhered by integral molding is known. Yes.

  For example, a solid polymer fuel cell employs a structure in which a plurality of separators and MEAs are alternately stacked. And in order to form the flow path of the water produced | generated by the fuel, the oxidizing agent, and reaction, each gap | clearance between a separator and MEA is each provided with a gasket. The gap between the separator and the MEA is often very narrow, and a gasket must be placed at the same position on both sides of the MEA to obtain a sealing property. The Therefore, in order to increase the positioning accuracy of the gasket and increase the working efficiency, a configuration in which the gasket is integrally formed with the separator is often employed.

  As a method of integrally forming a gasket on a substrate such as a separator at a low cost, a method using screen printing is known. That is, first, the rubber raw material liquid is filled in the pattern by passing the rubber raw material liquid through the mask pattern with a squeegee while the mask on which the desired pattern is formed is put on the substrate. Then, after removing the mask, the rubber raw material liquid is cured to integrally mold the gasket.

  In the case of such screen printing, if the thickness of the rubber raw material liquid to be printed by one screen printing is too thick, the shape of the rubber raw material liquid is deformed when the mask is removed. Therefore, there is a limit to the thickness of the rubber raw material liquid that can be printed by one screen printing. Therefore, in order to form a gasket having a desired thickness, it is sometimes necessary to repeat the screen printing a plurality of times to print the rubber raw material liquid in multiple layers.

  Conventionally, a rubber solution obtained by dissolving a rubber material with a solvent, a liquid rubber that does not require a solvent, or the like is used as the rubber raw material liquid. When these rubber raw material liquids are used, in order to prevent the molded rubber layer from being peeled off, it is necessary that the surface on the other side to be printed is in a chemically unstable state. Therefore, for example, it is difficult to form a new rubber layer on the rubber surface where the crosslinking has progressed sufficiently. Therefore, when the rubber raw material liquid is printed in multiple layers as described above, the shape is slightly stabilized by a drying process or the like for each screen printing instead of performing a crosslinking process for each screen printing. Therefore, before the crosslinking proceeds, the operation of performing screen printing is repeated, and the layer of the rubber raw material liquid that is not crosslinked is made into a multilayer, and then the crosslinking treatment is performed collectively.

  However, if screen printing is performed without performing the crosslinking treatment, the rubber raw material liquid that has already been printed adheres to the mask during the second and subsequent mask attaching / detaching operations. There was a problem that the alignment was a difficult task. In addition, if the cross-linking treatment (curing treatment) is collectively performed after multi-layering, rubber shrinkage occurs at a time, so that the dimensional accuracy of the gasket is likely to be deteriorated (partial variation), and the interlayer is also peeled off. It is likely to occur.

In addition, when the surface of the mating member on which the rubber raw material liquid is printed is made of a resin material, the surface of the resin material and the rubber raw material liquid to be printed are prevented so that the molded rubber layer is not peeled off. In the meantime, it is necessary to provide an adhesive layer for increasing these adhesive forces, which causes an increase in cost.

In addition, there exists a technique disclosed by patent document 1, 2 as a related technique.
JP 2001-196078 A JP 2002-228001 A

  An object of the present invention is to provide a gasket molding method and a gasket which improve the quality while improving the working efficiency.

  The present invention employs the following means in order to solve the above problems.

That is, the molding method of the gasket of the present invention is:
A step of printing a liquid rubber having a self-adhesive property as a material of the gasket on the substrate by screen printing;
Curing the printed liquid rubber;
It is characterized by having.

  According to the present invention, since the liquid rubber as the material of the gasket has self-adhesiveness, even if the surface of the mating member to be printed is in a chemically stable state, it can be printed as it is, Even in this case, it is possible to prevent the molded rubber from peeling off. Therefore, even when the surface of the mating member is made of a resin material, an adhesive layer is not necessary, and printing on the surface of a rubber material that has been sufficiently cross-linked is possible.

  Moreover, it is good to shape | mold the gasket which consists of multiple layers by repeating screen printing several times.

  By carrying out like this, the gasket of desired thickness can be shape | molded, without losing a shape.

  And it is good to harden liquid rubber for every printing.

  As a result, the liquid rubber that has already been printed is cured during the second and subsequent mask attaching / detaching operations, so there is no problem that the liquid rubber adheres to the mask, and mask alignment is troublesome. There is no work. Moreover, since liquid rubber is hardened little by little, it can suppress that rubber contraction becomes large at once, and can improve the dimensional accuracy of a gasket. Also, by curing the liquid rubber for each printing, the dimensional variation at the time of curing can be absorbed by the next screen printing, so coupled with the suppression of rubber shrinkage as described above, synergistically the gasket The dimensional accuracy can be increased. Furthermore, peeling between layers can be further increased by suppressing the amount of rubber shrinkage. In the case of the present invention, as described above, since the liquid rubber has self-adhesive properties, a new rubber layer may be formed on the surface of the cured rubber (crosslinked rubber). Peeling between the rubber layers can be suppressed.

The gasket of the present invention is
In a gasket molded on a substrate,
A liquid rubber having a self-adhesive property as a material for the gasket is printed on the substrate by screen printing and then cured, and then molded on the substrate.

  Moreover, it is good to be comprised from several layers by repeating screen printing in multiple times.

  Moreover, it is good that the horizontal width in each layer is gradually narrowed toward the surface layer.

  In addition, said each structure can be employ | adopted combining as much as possible.

  As described above, according to the present invention, it is possible to improve quality while improving work efficiency.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

  The gasket according to the present invention can be applied to various devices, and a polymer electrolyte fuel cell can be given as an example of particularly suitably applied. Therefore, prior to description of the gasket molding method and gasket according to the embodiment of the present invention, the fuel cell will be briefly described with reference to FIG. FIG. 1 is a schematic cross-sectional view of a single cell of a fuel cell. Generally, a fuel cell is composed of a cell stack in which a plurality of single cells are overlapped. In FIG. 1, only a single cell is shown in a sectional view.

  The single cell 100 includes a pair of separators 10, an MEA 20 provided between the pair of separators 10, and a gasket 30 provided between the separator 10 and the MEA 20. Here, the MEA 20 is obtained by integrating an electrolyte membrane, a pair of catalyst layers provided between the electrolyte membranes, and a pair of gas diffusion layers.

  In addition, regions K1 and K2 surrounded by the separator 10, the MEA 20, and the gasket 30 are formed on both sides of the MEA 20, respectively. A fuel (containing hydrogen) is supplied to one of these regions K1 and K2, and an oxidant (containing oxygen, generally air) is supplied to the other. As a result, in the catalyst layer on the anode side (fuel side) of the MEA 20, a reaction in which hydrogen is separated into protons and electrons occurs. Protons generated by this reaction move in the electrolyte membrane with water molecules, and electrons move to the cathode side (oxidant side) through an external circuit. In the catalyst layer on the cathode side, protons and electrons moving from the anode side react to generate water. The above is the power generation principle of the fuel cell.

  In the single cell 100 configured as described above, since the MEA 20 is a flexible member, if the gaskets 30 provided on both sides of the MEA 20 are not overlapped, the elastic repulsive force of the gasket 30 is insufficient. Thus, a stable sealing property cannot be obtained. Therefore, the gasket 30 is required to have high positioning accuracy.

  In general, since the gap between the separator 10 and the MEA 20 is very narrow, it is troublesome to attach a single gasket between them, and it is difficult to increase the positioning accuracy.

Therefore, in this single cell 100, the gasket 30 is integrally formed with the separator 10. Thereby, in the operation of assembling the fuel cell, the operation of mounting the gasket 30 can be omitted, and the positioning accuracy of the gasket 30 with respect to the separator 10 can be increased.

  Hereinafter, a molding method for integrally molding a gasket on a substrate and examples of the gasket obtained by the method will be described.

Example 1
With reference to FIG. 2, the molding method and gasket according to Example 1 of the present invention will be described. FIG. 2 is a schematic cross-sectional view of a gasket according to Embodiment 1 of the present invention. FIG. 2 shows a cross section in the vicinity of the gasket in a gasket formed on a base (here, a separator).

  The gasket 31 according to the present embodiment has a single-layer structure and is integrally formed with the separator 10 serving as a base. As the material of the gasket 31, liquid rubber having self-adhesive properties including an adhesive component is used. In addition, as a suitable example of the liquid rubber having self-adhesive properties, SIFEL 600 series (a particularly preferred example is SIFEL 604) manufactured by Shin-Etsu Chemical Co., Ltd. can be mentioned.

  In forming the gasket, first, liquid rubber having self-adhesive properties is printed on the separator 10 by screen printing as described above.

  Since screen printing is a well-known technique, the details will be omitted and a brief description will be given. In the screen printing, first, the separator 10 is covered with a mask in which a pattern having a desired shape (the shape of a gasket to be formed) is formed. The pattern is configured by through holes such as notches. Then, an appropriate amount of liquid rubber is placed on the mask, and this liquid rubber is moved by the squeegee so as to pass the pattern. Thereby, liquid rubber is filled in the pattern. Thereafter, by removing the mask, the liquid rubber is printed on the separator 10 in a desired shape.

  And after screen printing, liquid rubber is hardened by bridge | crosslinking. The cross-linking method varies depending on the properties of the liquid rubber. For example, there are a method of cross-linking by drying in a room temperature environment and a method of cross-linking by a physical action such as ultraviolet radiation.

  As described above, the gasket 31 can be integrally formed with the separator 10. In this embodiment, since the liquid rubber having self-adhesiveness is used as the material of the gasket 31, the separator 10 and the gasket 31 can be formed without providing an adhesive layer between the separator and the gasket as in the prior art. Can sufficiently increase the adhesive strength.

  As described above, according to the gasket molding method and gasket according to the present embodiment, it is possible to suppress the gasket from being peeled off from the separator without providing an adhesive layer. Can be maintained for a long time.

  As a more specific example, SIFEL 604 made by Shin-Etsu Chemical Co., Ltd. is used as a liquid rubber having self-adhesive properties, and this is printed on the surface of a carbon separator by screen printing, and then dried at room temperature in an air atmosphere. Cross-linked. The thickness of the rubber layer (gasket) obtained by molding was 100 μm. The adhesion between the rubber layer and the separator was strong, and it was difficult to peel off the rubber layer from the separator.

As another example, SIFE made by Shin-Etsu Chemical Co., Ltd. is used as a liquid rubber having self-adhesive properties.
Using L604, this was printed on a polyimide film surface by screen printing, then dried at room temperature and crosslinked in an air atmosphere. The thickness of the rubber layer (gasket) obtained by molding was 100 μm. The adhesion between the rubber layer and the film was strong, and it was difficult to peel off the rubber layer from the film.

  On the other hand, as a comparative example, SIFEL 3155 manufactured by Shin-Etsu Chemical Co., Ltd. was used as a liquid rubber having no self-adhesive properties, and this was printed on the surface of a carbon separator by screen printing, and then dried at room temperature in an air atmosphere. Cross-linked. The thickness of the rubber layer (gasket) obtained by molding was 100 μm. The adhesion between the rubber layer and the separator was weak, and it was easy to peel off the rubber layer from the separator.

  As another comparative example, SIFEL 3155 manufactured by Shin-Etsu Chemical Co., Ltd. was used as a liquid rubber having no self-adhesive properties, and this was printed on a polyimide film surface by screen printing and then dried at room temperature in an air atmosphere. Cross-linked with The thickness of the rubber layer (gasket) obtained by molding was 100 μm. The adhesion between the rubber layer and the film was weak, and it was easy to peel off the rubber layer from the film.

(Example 2)
With reference to FIG. 3, the gasket molding method and gasket according to Embodiment 2 of the present invention will be described. FIG. 3 is a schematic cross-sectional view of a gasket according to Embodiment 2 of the present invention. FIG. 3 shows a cross section in the vicinity of the gasket in the gasket formed on the base (here, the separator).

  The gasket 32 according to the present embodiment has a multilayer structure (specifically, a five-layer structure) and is integrally formed with the separator 10 serving as a base. As the material of the gasket 32, liquid rubber having self-adhesive properties including an adhesive component is used as in the case of the first embodiment.

  In forming the gasket, first, liquid rubber having self-adhesive properties is printed on the separator 10 by screen printing. The screen printing is as described above. After the screen printing for one layer is completed, the liquid rubber is cured by crosslinking. The crosslinking method is also as described above.

  By repeating such screen printing and crosslinking treatment, the gasket 32 having a multilayer structure is formed. Also in this embodiment, since the liquid rubber having self-adhesiveness is used as the material of the gasket 32, the adhesive force between the separator 10 and the gasket 32 can be sufficiently increased as in the above embodiment. Further, even when a rubber layer is formed on the surface of a rubber layer that has undergone crosslinking treatment and has been crosslinked, the adhesion between the rubber layers can be sufficiently increased.

  As described above, according to the gasket molding method and gasket according to the present embodiment, it is possible to prevent the gasket from being peeled off from the separator without providing an adhesive layer, and between the rubber layers in the gasket 32 having a multilayer structure. Since peeling can also be suppressed, stable sealing performance can be maintained over a long period of time while suppressing molding costs. And the gasket 32 of desired thickness can be obtained by setting it as a multilayer structure.

Further, in this embodiment, since the liquid rubber is cured by cross-linking every time screen printing is performed, there are the following advantages compared to the case where the liquid rubber is printed together and then cured by cross-linking. That is, in the screen printing, the liquid rubber that has already been printed is cured during the second and subsequent mask attaching / detaching operations, so there is no problem that the liquid rubber adheres to the mask, and the mask alignment is performed. There is no troublesome work. Moreover, since liquid rubber is hardened little by little, it can suppress that rubber contraction becomes large at once, and gasket 32
Dimensional accuracy can be improved. Further, by curing the liquid rubber for each printing, the dimensional variation at the time of curing can be absorbed by the next screen printing, so that the gasket 32 is synergistically coupled with the suppression of the amount of rubber shrinkage as described above. Dimensional accuracy can be improved. Furthermore, peeling between layers can be further increased by suppressing the amount of rubber shrinkage.

  As a more specific example, SIFEL 604 made by Shin-Etsu Chemical Co., Ltd. is used as a liquid rubber having self-adhesive properties, and this is printed on the surface of a carbon separator by screen printing, and then dried at room temperature in an air atmosphere. Cross-linked. Then, such screen printing and crosslinking treatment were repeated 5 times to form a gasket composed of five rubber layers on the separator. The thickness of the rubber layer (gasket) obtained by such molding was 500 μm. The adhesion between the rubber layer and the separator and the adhesion between the rubber layers were strong, and it was difficult to peel off the rubber layer from the separator or peel off the rubber layer.

  On the other hand, as a comparative example, SIFEL 3155 manufactured by Shin-Etsu Chemical Co., Ltd. was used as a liquid rubber having no self-adhesive properties, and this was printed on the surface of a carbon separator by screen printing, and then dried at room temperature in an air atmosphere. Cross-linked. Then, such screen printing and crosslinking treatment were repeated 5 times to form a gasket composed of five rubber layers on the separator. The thickness of the rubber layer (gasket) obtained by such molding was 500 μm. The adhesion between the rubber layer and the separator and the adhesion between the rubber layers were weak, and it was easy to peel off the rubber layer from the separator or peel off the rubber layer.

(Example 3)
With reference to FIG. 4, a gasket molding method and gasket according to Embodiment 3 of the present invention will be described. FIG. 4 is a schematic cross-sectional view of a gasket according to Embodiment 3 of the present invention. FIG. 4 shows a cross section in the vicinity of the gasket in the gasket formed on the base (here, the separator).

  Similarly to the case of the first embodiment, the gasket 33 according to the present embodiment also has a multilayer structure (specifically, a three-layer structure in the present embodiment), and is integrally formed with the separator 10 serving as a base.

  In the case of the present embodiment, as is apparent from the figure, the lateral width of each rubber layer constituting the gasket 33 is gradually narrowed toward the surface layer. Thereby, when the gasket 33 is compressed, the peak surface pressure in the vicinity of the center is increased, so that the sealing performance can be improved.

  The advantages relating to the gasket 33 having a multilayer structure are the same as in the case of the second embodiment, and the description thereof is omitted.

FIG. 1 is a schematic cross-sectional view of a single cell of a fuel cell. FIG. 2 is a schematic cross-sectional view of a gasket according to Embodiment 1 of the present invention. FIG. 3 is a schematic cross-sectional view of a gasket according to Embodiment 2 of the present invention. FIG. 4 is a schematic cross-sectional view of a gasket according to Embodiment 3 of the present invention.

Explanation of symbols

10 Separator 20 MEA
30, 31, 32, 33 Gasket 100 single cell

Claims (6)

A step of printing a liquid rubber having a self-adhesive property as a material of the gasket on the substrate by screen printing;
Curing the printed liquid rubber;
A method for forming a gasket, comprising:   The gasket forming method according to claim 1, wherein a gasket composed of a plurality of layers is formed by repeating screen printing a plurality of times.   3. The gasket molding method according to claim 2, wherein the liquid rubber is cured for each printing. In a gasket molded on a substrate,
A gasket characterized in that a liquid rubber having a self-adhesive property, which is a material for a gasket, is molded on a substrate by being printed on the substrate by screen printing and then cured.   The gasket according to claim 4, wherein the gasket is composed of a plurality of layers by repeating screen printing a plurality of times.   6. The gasket according to claim 5, wherein the lateral width of each layer is gradually narrowed toward the surface layer.

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