JP7261614B2 - Gasket manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing a gasket using screen printing.

BACKGROUND ART Conventionally, a method of manufacturing a gasket by screen printing on a base material such as a separator provided in a fuel cell is known. In addition, among such techniques, there is known a technique of forming projections (beads) on a base material and providing gaskets on the projections by screen printing in order to improve sealing performance (Patent Document 1, 2).

Generally, in screen printing, a material applied to a base material flows due to the attractive force of the base material and the surface tension of the material, and is deformed so that the irregularities on the surface are smoothed. However, in the case of materials with high viscosity and low leveling properties, it is difficult to flow, so it is known that a phenomenon (called a saddle phenomenon) occurs in which the thickness in the center in the transverse direction is thin and the thickness at both ends is thick. (see Patent Document 3). Such a saddle phenomenon is more likely to occur as the width in the lateral direction increases.

FIG. 8 shows a state in which the saddle phenomenon occurred in the gasket provided on the convex portion formed on the base material. Note that FIG. 8 is a cross-sectional view of the base material and the gasket cut perpendicularly to the direction in which the gasket extends (longitudinal direction). As shown in the figure, the gasket 750 provided on the convex portion 710 formed on the base material 700 has a smaller thickness at the center in the lateral direction and a larger thickness at both ends. If such a saddle phenomenon occurs, the thickness of the gasket 750 near the center in the lateral direction is thin, so there is a risk that the sealing performance will deteriorate. In addition, depending on the usage environment and the required sealing performance, the thickness of the gasket must be increased, and repeated screen printing may result in the gasket having a multi-layered structure.

FIG. 9 shows a case where a multi-layered gasket is provided on the substrate. Note that FIG. 9 also shows a cross-sectional view of the substrate and the gasket cut perpendicularly to the direction in which the gasket extends (longitudinal direction). As shown, the gasket 850 provided on the convex portion 810 formed on the substrate 800 includes a first thin film layer 851 provided on the convex portion 810 and a second thin film layer 851 provided on the first thin film layer 851 . and a thin film layer 852 . In this gasket 850, a first thin film layer 851 and a second thin film layer 852 are provided by repeating screen printing twice using a screen plate having the same shape and size. As shown in the figure, the saddle phenomenon occurs in the first thin film layer 851 and becomes even more pronounced in the second thin film layer 852 . G in the figure indicates the range of the standard, and if the central dimension in the transverse direction of the gasket 850 is to be within the range of the standard G, both ends in the transverse direction will be thicker than the standard G. Therefore, the sealing becomes unstable.

WO2017/077900 WO2017/212775 JP 2006-335045 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a gasket that can uniformize the thickness of the gasket formed on the convex portion.

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

The method for manufacturing the gasket of the present invention comprises:
In a method for manufacturing a rubber-like elastic gasket formed by screen printing on a convex portion formed on a base material,
A first thin film layer is formed on the protrusions by screen printing using a first screen plate in which the width in the width direction of the opening through which the material passes is narrower than the width in the width direction of the manufactured gasket. a first step of
After the first step, using a second screen plate designed so that the width in the width direction of the opening through which the material passes is the same as the width in the width direction of the manufactured gasket, the first thin film layer A second step of forming a second thin film layer by screen printing on the surface side of the
characterized by having

According to the present invention, the first thin film layer is formed using the first screen plate in which the width in the widthwise direction of the opening through which the material passes is narrower than the width in the widthwise direction of the manufactured gasket. , the occurrence of saddle phenomenon can be suppressed. The second thin film layer is formed using a second screen plate designed so that the width in the width direction of the opening through which the material passes is the same as the width in the width direction of the manufactured gasket. be. However, since the second thin film layer is formed closer to the surface side than the first thin film layer, at the ends of the second thin film layer in the width direction, during screen printing, one of the materials of the second thin film layer flow out to the outside of the lateral ends of the first thin film layer. Thereby, in the second thin film layer, it is possible to prevent the thickness of the ends in the width direction from becoming thicker than the thickness of the center.

The second thin film layer is preferably formed so as to protrude from both lateral sides of the first thin film layer.

As a result, it is possible to prevent the second thin film layer from becoming thicker at both ends in the widthwise direction than in the center in the widthwise direction.

The second thin film layer is preferably formed so as to be in contact with the surface of the first thin film layer and the portions of the surface of the protrusion on both sides of the first thin film layer in the lateral direction.

As described above, according to the present invention, the thickness of the gasket formed on the projection can be made uniform.

FIG. 1 is a schematic cross-sectional view of a sealing structure according to an embodiment of the invention. FIG. 2 is a plan view of a gasket according to an embodiment of the invention. FIG. 3 is a schematic cross-sectional view of a gasket according to an embodiment of the invention. FIG. 4 is a plan view of a first screen plate used in the method of manufacturing a gasket of the present invention. FIG. 5 is an explanatory diagram for explaining the screen printing method. FIG. 6 is a plan view of a second screen plate used in the gasket manufacturing method of the present invention. FIG. 7 is a schematic cross-sectional view of a gasket according to a modification of the invention. FIG. 8 is a schematic cross-sectional view of a conventional gasket. FIG. 9 is a schematic cross-sectional view of a conventional gasket.

BEST MODE FOR CARRYING OUT THE INVENTION A mode for carrying out the present invention will be exemplarily described in detail below based on an embodiment with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention only to them, unless otherwise specified. .

(Example)
A method of manufacturing a gasket according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6. FIG. In this embodiment, a case where a gasket is provided on a separator in a fuel cell will be described.

<Sealed structure>
A sealing structure according to this embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of a sealing structure according to an embodiment of the present invention, more specifically, a schematic cross-sectional view of a fuel cell. A fuel cell is generally configured as a cell stack consisting of a plurality of single cells. FIG. 1 shows a schematic cross-sectional view of a unit cell 10. As shown in FIG. The unit cell 10 includes a pair of separators 100 as base materials and an MEA (Membrane Electrode Assembly) provided between the pair of separators 100 . The MEA comprises an electrolyte membrane 200 and a pair of gas diffusion layers 300 provided on both sides of the electrolyte membrane 200 . Further, the separator 100 is configured by a plate-like member made of metal or the like. The separator 100 is formed with a channel 120 through which a fuel gas, an oxidant gas, or the like flows.

The single cell 10 is provided with a gasket 150 made of a rubber-like elastic material to prevent fuel gas, oxidant gas, and the like from leaking to the outside. Suitable examples of materials for the gasket 150 include VMQ, EPDM, and FKM. The gasket 150 is provided on the protrusions (beads) 110 formed on the separator 100 . This gasket 150 seals the gap between the separator 100 and the electrolyte membrane 200 .

<Gasket>
In particular, with reference to FIGS. 2 and 3, gasket 150 will be described in greater detail. FIG. 2 is a plan view of gasket 150 provided on separator 100 according to an embodiment of the present invention. 2, the channel 120 provided in the separator 100 is omitted. FIG. 3 is a schematic cross-sectional view of the gasket 150 provided in the separator 100 according to the embodiment of the invention, and corresponds to the AA cross-sectional view in FIG. That is, FIG. 3 shows a part of a cross-sectional view of the separator 100 and the gasket 150 cut perpendicularly to the direction (longitudinal direction) in which the protrusions 110 and the gasket 150 of the separator 100 extend. That is, the gasket 150 in FIG. 3 is a cross-sectional view of the gasket 150 cut in its lateral direction.

The gasket 150 is provided inside the outer edge of the separator 100 on the convex portion 110 formed along the outer edge. Gasket 150 is provided so as to cover the entire surface of convex portion 110 . The gasket 150 according to this embodiment is composed of a first thin film layer 151 provided so as to be in contact with the surface of the convex portion 110 and a second thin film layer 152 provided closer to the surface than the first thin film layer 151. be. The first thin film layer 151 is provided near the center of the protrusion 110 along the direction (longitudinal direction) in which the protrusion 110 extends. The width of the first thin film layer 151 in the lateral direction is narrower than the width of the protrusion 110 in the lateral direction. The second thin film layer 152 is provided so as to protrude from both sides of the first thin film layer 151 in the lateral direction. More specifically, the second thin film layer 152 is provided so as to contact the surface of the first thin film layer 151 and both sides of the first thin film layer 151 in the lateral direction of the surface of the projection 110 . (See Figure 3). The gasket 150 according to this embodiment is provided so that the width S in the lateral direction is constant over the entire circumference.

<Manufacturing method of gasket>
In particular, a method of manufacturing the gasket 150 according to this embodiment will be described with reference to FIGS. 4 to 6. FIG. 4 and 6 are plan views of screen plates used in the method of manufacturing a gasket of the present invention. FIG. 5 is an explanatory diagram for explaining the screen printing method. The screen plate 500 in FIG. 5 corresponds to the BB cross-sectional view in FIG.

The gasket 150 according to this embodiment is formed by screen printing on the protrusions 110 formed on the separator 100 . Also, in this embodiment, the gasket 150 is formed by performing screen printing twice. Hereinafter, the printing process by the first screen printing will be referred to as the first process, and the printing process by the second screen printing will be referred to as the second process.

<<First step>>
In the first step, screen printing is performed using a first screen printing plate 500 shown in FIGS. The first screen plate 500 is composed of a mask 510 and a mesh screen 520 provided on one side of the mask 510 . The mask 510 is provided with an opening 511 through which the material (rubber material) of the gasket 150 passes. A width T in the lateral direction of the opening 511 is set narrower than a width S in the lateral direction of the gasket 150 after manufacturing. Using the first screen plate 500 configured as described above, the first thin film layer 151 is formed on the convex portions 110 of the separator 100 by screen printing.

Screen printing will be described with reference to FIG. First, the separator 100 is covered with the first screen plate 500 so that the mask 510 faces the separator 100 side. A material 150X of the gasket 150 is supplied to the surface side of the first screen plate 500 (the surface side of the screen 520). Then, the squeegee 550 moves so as to slide on the surface of the screen 520 while being pressed toward the separator 100 (moves in the direction of arrow M in the figure). As a result, when the squeegee 550 passes over the openings 511 , part of the material 150X passes through the openings 511 and is pushed out onto the protrusions 110 of the separator 100 . The extruded material 151X is then cured by cross-linking to form the first thin film layer 151 .

<<Second step>>
In the second step, screen printing is performed using a second screen plate 600 shown in FIG. The second screen plate 600 also comprises a mask 610 and a mesh screen 620 provided on one side of the mask 610 . The mask 610 is provided with an opening 611 through which the material (rubber material) of the gasket 150 passes. The width S of the opening 611 in the lateral direction is designed to be the same as the width S of the gasket 150 after manufacturing in the lateral direction. Using the second screen plate 600 configured as described above, the second thin film layer 152 is formed by screen printing on the surface side of the first thin film layer 151 .

The screen printing method is as described in the first step. When the second screen plate 600 is placed on the separator 100, the center line of the opening 611 of the second screen plate 600 (the line connecting the centers in the lateral direction) and the center line of the first thin film layer 151 The opening 611 is designed so that (a line connecting the centers in the lateral direction) coincides with the line.

By performing screen printing using the second screen plate 600 configured as described above, the second thin film layer 152 is formed, and the gasket 150 described above is manufactured.

<Excellent points of the method for manufacturing a gasket according to the present embodiment>
According to the manufacturing method according to the present embodiment, the first thin film layer 151 has a lateral width T of the opening 511 through which the material passes, which is narrower than a lateral width S of the manufactured gasket 150 . It is formed using one screen plate 500 . Therefore, the occurrence of the saddle phenomenon can be suppressed. That is, as described in the background art, in the case of a material (rubber material) having high viscosity and low leveling property, the saddle phenomenon is likely to occur in the material applied by screen printing. However, if the width in the lateral direction is narrow, the occurrence of the saddle phenomenon can be suppressed. Therefore, by setting the width T in the lateral direction of the opening 511 to such an extent that the saddle phenomenon does not occur in accordance with the characteristics of the material 150X of the gasket 150, the saddle phenomenon does not occur in the first thin film layer 151. It can be suppressed.

The second thin film layer 152 is a second screen plate designed so that the width S in the widthwise direction of the opening 611 through which the material passes is the same as the width S in the widthwise direction of the gasket 150 after manufacturing. 600. However, since the second thin film layer 152 is formed closer to the surface side than the first thin film layer 151, at the ends of the second thin film layer 152 in the width direction, the second thin film layer 152 may not be formed in the screen printing. flows out to the outside of the lateral ends of the first thin film layer 151 . Accordingly, in the second thin film layer 152, it is possible to prevent the thickness of the ends in the lateral direction from becoming thicker than the thickness of the center. Therefore, the thickness of the gasket 150 formed on the convex portion 110 can be more reliably made uniform. In this embodiment, the second thin film layer 152 is formed so as to protrude from both sides of the first thin film layer 151 in the short direction. It is possible to prevent the thickness from becoming thicker than the center in the hand direction.

As described above, according to the manufacturing method according to the present embodiment, the thickness of the gasket 150 formed on the convex portion 110 can be made uniform even when a material having high viscosity and low leveling property is used. .

Here, screen printing is performed using the first screen plate 500 with the width T of 1.0 mm to form the first thin film layer 151, and then the second screen plate 600 with the width S of 1.8 mm. was used to form the second thin film layer 152 by screen printing. When the gasket 150 having a width S in the transverse direction of 1.8 mm and a thickness (height) of 20 μm or more and 100 μm or less was manufactured in this way, the thickness of the gasket 150 could be made uniform. In addition, in the gasket 150 obtained by this manufacturing method, the thickness near the center of the width in the width direction can be well within the standard, and the width near both ends in the width direction is thinner than the thickness near the center. , it was confirmed that a stable sealing performance was obtained.

On the other hand, screen printing was performed twice using a screen plate having an opening width of 1.4 mm in the lateral direction. As a result, the saddle phenomenon occurred in the thin film layer obtained by the first screen printing, and the saddle phenomenon became more pronounced in the thin film layer obtained by the second screen printing. As a result, the gasket obtained by this manufacturing method was able to keep the thickness near the center of the width in the width direction within the standard, but the width near both ends in the width direction was thicker than the thickness near the center. Couldn't keep up with the standard.

(others)
In the above embodiment, the convex portion 110 formed on the separator 100 has a flat upper surface. However, the present invention is not limited to such projections 110, and can be applied to gaskets formed for projections of different shapes. For example, FIG. 7 shows a schematic cross-sectional view of a gasket according to a modification of the invention. As shown in FIG. 7, even if the upper surface of the convex portion 110Y formed on the separator 100Y has a flat surface in the center and inclined surfaces at both ends, the upper surface of the convex portion 110Y is formed on the upper surface of the separator 100Y. The manufacturing method of the present invention can be applied to the gasket 150Y that is formed. Even in this case, a gasket 150Y composed of a first thin film layer 151Y with a narrow width in the width direction and a second thin film layer 152Y with a width in the width direction equal to the width in the width direction of the protrusion 110Y is manufactured. be done.

Moreover, in the above embodiment, the case where the two-layer gasket 150 is manufactured by screen printing twice has been described. However, the present invention can also be applied to manufacturing a gasket having a structure of three or more layers by screen printing three times or more. That is, the present invention also includes a case where a gasket having a structure of three or more layers is manufactured by adding one or more screen printing steps between the first step and the second step. In this case, the first screen plate 500 used in the first step can be used as the screen plate for screen printing between the first step and the second step. In addition, regarding the screen plate used for screen printing between the first step and the second step, the screen plate is successively increased so that the width of the opening through which the gasket material passes is gradually widened. Replacement is also preferred.

Furthermore, in the above embodiments, the case where the gasket is provided on the separator of the fuel cell has been described as an example. However, gaskets according to the present invention are not limited to such uses. For example, the present invention can be applied to a case where a gasket made of a rubber-like elastic material is provided on a convex portion (bead) of a metal gasket.

10 Single cell 100,100Y Separator 110,110Y Protrusion 120 Channel 150,150Y Gasket 150X, 151X Material 151,151Y First thin film layer 152,152Y Second thin film layer 200 Electrolyte membrane 300 Gas diffusion layer 500 First screen plate 510 Mask 511 Opening 520 Screen 550 Squeegee 600 Second screen plate 610 Mask 611 Opening 620 Screen

Claims (3)

In a method for manufacturing a rubber-like elastic gasket formed by screen printing on a convex portion formed on a base material,
A first thin film layer is formed on the protrusions by screen printing using a first screen plate in which the width in the width direction of the opening through which the material passes is narrower than the width in the width direction of the manufactured gasket. a first step of
After the first step, using a second screen plate designed so that the width in the width direction of the opening through which the material passes is the same as the width in the width direction of the manufactured gasket, the first thin film layer A second step of forming a second thin film layer by screen printing on the surface side of the
A method for manufacturing a gasket, comprising: 2. The method of manufacturing a gasket according to claim 1, wherein the second thin film layer is formed so as to protrude from both lateral sides of the first thin film layer. 3. The second thin film layer is formed so as to be in contact with the surface of the first thin film layer and the portions of the surfaces of the projections on both sides of the first thin film layer in the transverse direction. A method for manufacturing the described gasket.

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