JPS6065405A - Sheetlike elastic conductive plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a sheet-like elastic conductive plate, and more particularly to a sheet-like conductive plate or a sheet-like electrode that has a large area and a relatively thin thickness.

[Prior art and its problems]

One possible use of the sheet-like conductive plate is as a notebook-like electrode used in a laminated structure such as a separate plate of a fuel cell. In this type of application, conductivity is required not only in a direction parallel to the sheet surface but also in a direction perpendicular to the sheet surface (in other words, in the thickness direction). In particular, the latter vertical conductivity does not directly affect the battery's power output or efficiency. In addition, in recent years, due to the demand for higher output of fuel cells, sheet electrodes have gradually become larger in area.

The factors that influence this vertical conductivity are, on the one hand, the conductivity of the materials used, and on the other hand, the degree of contact resistance when laminating one layer at a time.

On the other hand, although sheet electrodes differ depending on the type of fuel cell, they are required to have good compression characteristics because they are laminated at high temperatures and used under pressure for long periods of time.

Conventionally, as this type of sheet-like electrode, taking a phosphoric acid type battery as an example, a tantalum plate (metal plate), a phenol resin-impregnated graphite sintered plate, a graphite powder-dispersed phenol resin molded plate, etc. can be considered. Although these materials have excellent electrical conductivity and compression properties at high temperatures, studies have revealed that they have high contact resistance when laminated.

That is, using a porous carbon plate as the mating material, the respective resistances of a tantalum plate, a phenol resin-impregnated graphite sintered plate, and a graphite powder-dispersed phenol resin molded plate were measured while changing the pressing force. The results are shown in FIG. 1, 2 and 3 in this figure are the results for these materials, respectively. Although there is a slight difference in the resistance/value (comparison index) of the above three materials and the porous carbon plate in the range of small pressurizing force,
As the pressure was increased, the difference decreased, but the resistance did not decrease to the original target value, and the porous carbon plate was destroyed at a Calo pressure of about 3 Kg/ctl. For this reason, the mechanical strength of the porous carbon plate and the three materials mentioned above was improved, and the study was conducted again, but none of the expected effects could be obtained. In addition, even when machining is performed, simple methods are not necessarily effective when processing large-area and thin plates, and special processing methods are required to ensure uniformity of thickness and to prevent warping of the plate. It turned out to be.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks, and provides a sheet-like elastic conductive plate that has low contact resistance with adjacent conductive plates and has good compressive cleave characteristics (75) and less deformation when used under pressure. The purpose is to provide

[Key points of the invention]

The sheet-like elastic conductive plate according to the present invention is constructed by allowing a comb composition formed by dispersing and mixing a conductive filler to exist on both sides of a conductive sheet that undergoes little compressive deformation during lamination.

That is, the present invention uses a rubber composition that can fit well with adjacent plates with a small pressing force as a measure to improve contact resistance, and the use of this rubber composition conversely prevents disadvantages such as compression creep. The characteristic is the shape ratio of large area and thin wall (
The main feature is that this improvement was achieved by increasing the ratio of pressure receiving area to free surface area and by placing a material with little compressive deformation in the intermediate layer to create a sandwich structure.

In the present invention, the rubber composition in which the conductive filler is dispersed and mixed includes polytetrafluoroethylene, polyhexafluoropropylene, polychlorol-1) fluoroethylene, hexafluoropropylene, and vinylidene fluoride. From the viewpoint of heat resistance, fluororubbers such as a copolymer of tetrafluoroethylene and hexafluoropropylene are preferred. However, if the usage requirements are relaxed, polyisoprene, butadiene styrene rubber,
acryloni) l) Rubber, butyl rubber, neoprene,
Rubbers such as polybutadiene can also be used.

For example, the above-mentioned fluororubber is preferably used for applications that require heat resistance, such as silicic acid fuel cells.

These are usually used in the form of water dispersions or pastes. Examples of the filler that imparts conductivity to the rubber composition include graphite, carbon black, carbon fiber, conductive metal powder, and fiber. The type and amount of these conductive fillers can be easily determined depending on the requirements during use. The amount of filler used is generally 2
The amount is 0 to 80% by weight, preferably 30 to 70% by weight.

The sheet or plate material disposed as an intermediate layer in the sheet-like elastic conductive plate of the present invention may be any material as long as it has less compressive deformation than the rubber composition and is electrically conductive. A plate, a conductive plastic sheet or four plates, a graphite sintered body and its resin-impregnated material, a carbon fiber sheet, etc. are effective.

The comb composition can be easily applied to both sides of the conductive sheet by a conventional pressure roll method, compression molding method, or the like. The thickness of the conductive sheet material and the rubber composition can be appropriately selected as required.

〔Example〕

The present invention will be explained below using specific examples.

A conductive pasty rubber composition consisting of 75 parts by weight of graphite and 50 parts by weight of fluororubber latex (polytetrafluoroethyl, ren aqueous solution, concentration 50% by weight) was preformed by a pressure roll method or compression molding method, and dried. A sheet-like material was obtained by processing.

This sheet-like material was placed on both sides of a tantalum plate and cured by heating to obtain a plate-like elastic conductive plate in which a rubber composition was placed on both upper and lower surfaces of the tantalum plate.

This sheet-like conductive plate and porous carbon plate are placed adjacent to each other,
Resistance values were measured as described above.

The results are shown in Figure 1. In this figure, 4 is a curve showing the results.

From FIG. 1, it can be seen that in the sheet-like conductive plate 4 according to the present invention, it is possible to obtain a low resistance value originally provided by the material under a relatively small pressing force. That is, the contact resistance during lamination does not need to be considered under a relatively small pressing force and can be ignored.

On the other hand, regarding the compressive deformation characteristics that are a problem when laminating rubber compositions, (1) a small resistance value can be obtained in a region where the pressing force is extremely small compared to the conventional study example; (2) (3) Even with a rubber composition, the shape ratio is large because it is thin and has a large area. Since the composition has a structure with very little compression deformation, no compression deformation as expected from ordinary rubber compositions is observed.

〔Effect of the invention〕

According to the present invention, since a rubber composition in which a conductive filler is dispersed and mixed is present on both sides of a conductive sheet material that undergoes little compressive deformation during lamination, contact resistance with adjacent conductive plates is reduced. It is possible to obtain a sheet-like elastic conductive plate that has a low deformation due to compression when used in a pressurized state.

[Brief explanation of the drawing]

FIG. 1 is a curve showing the relationship between resistance and pressing force between various conductive plates and porous carbon plates. Here, 1, 2, and 3 indicate the curves of the conductive plate of the comparative example, and 4 indicates the curve of the conductive plate according to the present invention. Patent Applicant: Tomishichi Co., Ltd. Sohofuji Fuji Electric Manufacturing Co., Ltd.

Claims (1)

[Scope of Claims] 1) A sheet-like elastic conductive plate, characterized in that a rubber composition in which a conductive filler is dispersed and mixed is present on both sides of a conductive sheet-like material that is not compressively deformed. 2. In the sheet-like elastic conductive plate according to claim 1, the conductive sheet material is carbon fiber cloth, a conductive phenolic resin-impregnated sintered plate, a conductive graphite powder-dispersed phenol molded plate, or a conductive metal. A sheet-like elastic conductive plate characterized by the following. 3) The sheet-like elastic conductive plate according to claim 1, wherein the conductive filler is graphite, carbon black, carbon fiber, metal powder, or metal fiber. 4) The sheet-like elastic conductive plate according to claim 1, which has a large area and a small thickness.