JP4656369B2 - Method of molding rubber packing for fuel cell - Google Patents

Description

  The present invention relates to a method of integrally forming a rubber packing on a separator of a fuel cell, for example, a polymer electrolyte fuel cell, and in particular, a concave groove is formed as a sealing groove on a peripheral edge of the separator, and the rubber packing is filled in the concave groove. The present invention relates to a molding method.

Conventionally, it is a patent that a seal material is provided in the concave groove of the separator, and a seal material made of rubber or the like having a narrower tip than the depth of the seal groove is provided in the seal groove provided in the seal portion of the separator. It is described in Document 1.
Japanese Patent No. 3400415

And as a method of providing the sealing material on the separator, a sealing material molded separately from the separator is sandwiched between the separators during assembly, or the sealing material is bonded to the separator, or the separator is set in a mold, There is a method in which a sealing material is injected into a cavity in a mold and integrally molded.

On the other hand, as another method of providing a sealing material in the groove of the separator, as shown in Patent Document 2, a method using a screen printing method is known. In this method, the groove is filled with a printing material to form a flat surface, and a rubber solution is applied to the flat surface to form a rubber packing.
JP 2002-190307 A

  However, in the above-mentioned Patent Document 2, there is a problem that two steps of flattening the groove of the separator and a step of forming a rubber packing by applying a rubber solution are required, which necessitates troublesome work.

The present invention has been made in view of the above problems, and it is an object of the present invention to make it possible to form a rubber packing directly in a concave groove of a separator in one stage, thereby facilitating the molding operation. At the same time, an object is to allow the molded rubber packing to exhibit a good sealing function when the separator is assembled.

In order to achieve the above object, the present invention provides a frame-like rubber packing at the peripheral edge of a separator that sandwiches a unit cell of a fuel cell. A rubber packing molding method in which a rubber solution is filled and cured in a space partitioned in the center to integrally form a rubber packing, and a gap is continuously formed on the inner and outer peripheral sides of the groove. A step of preparing a screen mask having an inner peripheral spacer and an outer peripheral spacer projecting from a portion corresponding to the gap on the periphery of the printing surface, and arranging the screen mask on the surface of the separator A step of inserting a peripheral spacer and an outer peripheral spacer into the inner peripheral edge and the outer peripheral edge in the concave groove to partition the molding space of the frame-shaped rubber packing; A step of filling the molding space from the through hole of the screen mask to form an unvulcanized rubber coating layer, removing the screen mask together with the inner peripheral spacer and outer peripheral spacer, and the inner peripheral edge in the concave groove And a step of forming a void portion not filled with the rubber solution having a shape corresponding to the inner peripheral spacer and the outer peripheral spacer on the outer peripheral edge, vulcanizing the unvulcanized rubber coating layer, and adhering to the separator as the rubber packing A method for forming a rubber packing for a fuel cell, which includes a step of integrating and made deformable in the inner and outer peripheral directions in the gap, is used as means.

  In the method of the present invention, the work is simple, and there is a margin that the molded rubber packing can be deformed in the inner circumferential direction and the outer circumferential direction in the concave groove, and high sealing performance can be exhibited with a small tightening force.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of a unit cell 1 constituting a polymer electrolyte fuel cell formed by applying the method of the present invention. A normal fuel cell is a laminate in which a plurality of unit cells 1 are stacked (not shown). Z).

In FIG. 1, a single cell 1 includes a fuel cell body comprising a polymer electrolyte membrane 2 and a cathode electrode 3 and an anode electrode 4 disposed on both sides of the polymer electrolyte membrane 2, and a cathode electrode 3 and an anode. The separators 5 and 5 are provided so as to be in contact with the electrodes 4 respectively. A groove 7 for supplying an oxidizing gas is provided on the electrode 3 side of the cathode electrode side separator 5, and a groove 8 for supplying a fuel gas is provided on the electrode 4 side of the anode electrode side separator 5. The groove 8 communicates with a fuel gas supply pipe (not shown). The single cell 1 includes a fuel cell body made up of a polymer electrolyte membrane 2, a cathode electrode 3, and an anode electrode 4, and prevents leakage of fuel gas and oxidizing gas around the cathode electrode side separator 5 and anode electrode side. Frame-shaped rubber packings 9 and 9 for ensuring insulation between the separators 5 are interposed between the separators 5 and 5.

In the present invention, a groove 6 is formed as a seal groove on the peripheral edge of the separator 5, and a rubber solution (for example, liquid silicone rubber) is filled and cured in the groove 6 by screen printing. Are formed integrally, but the inner and outer peripheral sides of the rubber packing 9 formed into a frame shape, that is, the inner peripheral edge and the outer peripheral edge in the concave groove 6 are provided with void portions 10 and 10 that are not filled with the rubber solution. Is formed.

2 to 4 show a molding process of the rubber packing 9, and a screen mask 11 is used in this molding process. The screen mask 11 is composed of a screen mesh layer 12 and spacers 13 (inner peripheral side) and spacers 14 (outer peripheral side) which are integrally projected continuously from the periphery of the back surface (printing surface side). Reference numeral 15 denotes a photosensitive emulsion layer which is applied to the screen mesh layer 12 and then cured by exposure. In addition, the spacers 13 and 14 are provided at portions corresponding to the voids 10 and 10 inside the concave groove 6 of the separator 5, but may be formed of the above-described photosensitive emulsion layer, but are not limited thereto, rubber, synthetic resin Alternatively, a metal or the like may be integrally joined.

As shown in FIG. 3, the screen mask 11 is arranged on the surface of the separator 5 in which the concave groove 6 is formed, and the spacers 13 and 14 are inserted into the concave groove 6. A rubber solution such as liquid rubber is filled only in the space defined by the spacers 13 and 14 in the groove 6 through the through holes 16 not coated with the photosensitive emulsion, and then the screen mask 11 is removed (FIG. 4). The filled rubber solution is cured by heating at room temperature or as necessary to form a rubber packing 9 that is vulcanized and bonded in the groove 6. The rubber packing can be vulcanized by an appropriate vulcanization method in addition to radiation crosslinking such as electron beam irradiation.

FIG. 5 is a schematic plan view showing the separator in a state where the rubber packing 9 is formed. The rubber packing 9 is integrated in a frame shape in the center of the recessed groove 6 by vulcanization, and its inner and outer peripheral edges are integrated. The gaps 10 and 10 are continuously formed, and a room for deformation in the inner and outer peripheral directions when the rubber packing 9 is compressed is secured.

The schematic longitudinal cross-sectional view of the unit cell which comprises a polymer electrolyte fuel cell. The figure which shows a part of process of shape | molding rubber packing in the ditch | groove of a separator. The figure which shows a part of process of shape | molding rubber packing in the ditch | groove of a separator. The figure which shows a part of process of shape | molding rubber packing in the ditch | groove of a separator. The schematic plan view which shows the state by which the rubber packing was shape | molded in the ditch | groove of the separator.

Explanation of symbols

1 Unit Cell 2 Polymer Electrolyte Membrane 3 Cathode Electrode 4 Anode Electrode 5, 5 Separator 6 Groove 9 Rubber Packing 10, 10 Gap 11 Screen Mask 12 Screen Mesh Layer 13 Inner Side Spacer 14 Outer Side Spacer 15 Photosensitive Emulsion Layer 16 Through hole

Claims (1)

When forming a frame-shaped rubber packing on the peripheral edge of the separator that holds the unit cell of the fuel cell, the rubber solution is filled and cured in the space partitioned in the center of the concave groove formed as a sealing groove on the peripheral edge. A rubber packing molding method in which the rubber packing is integrally formed, and the gap is continuously formed on the inner circumferential side and the outer circumferential side in the groove,
Preparing a screen mask having an inner peripheral spacer and an outer peripheral spacer projecting from a portion corresponding to the gap on the periphery of the printing surface;
Disposing the screen mask on the surface of the separator and inserting the inner and outer peripheral spacers into the inner and outer peripheral edges of the groove to partition the molding space for the frame-shaped rubber packing ,
Filling a rubber solution into the molding space through the screen mask through a screen printing method to form an unvulcanized rubber coating layer;
The screen mask is removed together with the inner peripheral spacer and outer peripheral spacer, and the inner peripheral edge and the outer peripheral edge in the groove are not filled with a rubber solution having a shape corresponding to the inner peripheral spacer and outer peripheral spacer. Forming step,
A step of vulcanizing the unvulcanized rubber coating layer and bonding and integrating with the separator as the rubber packing;
A method of molding a rubber packing for a fuel cell that is deformable in the inner and outer circumferential directions in the gap.

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