| abstract |
A separator for fuel cells of solid polyelectrolyte type which overcomes the disadvantages of the prior art, is lightweight, can be slotted easily, and exhibits high gas barrier properties; and processes for the production thereof. The separator is of the type to be sandwiched between gas diffusion electrodes of the fuel cell and characterized by being made of the carbonaceous composite material comprising expanded graphite particles which have a mean particle diameter of 5 to 12 µm and at least 80 % of which have diameters falling within the range of 0.1 to 20 µm and a thermoplastic or thermosetting resin or a sinter thereof, wherein the graphite particles are dispersed in the resin of sinter thereof, and having slots for feeding oxidant gas or fuel gas on one or both surfaces thereof. The separator can be produced by mixing a thermoplastic or thermosetting resin with the above-specified expanded graphite particles, pressure-molding the obtained mixture at ordinary temperature to 400 °C and forming slots of feeding oxidant gas or fuel gas on one or both surfaces of the resulting carbonaceous composite material, or by mixing a thermosetting resin with the above graphite particles, pressure-molding the obtained mixture at ordinary temperature to 400 °C, firing the resulting molding in a nonoxidizing atmosphere at 700 to 3000 °C to form a carbonaceous composite material, and forming slots for feeding oxidant gas or fuel gas on one or both surfaces of the material, or by mixing a thermosetting resin with the above graphite particles, pressure-molding the obtained mixture at ordinary temperature to 400 °C, forming slots for feeding oxidant gas or fuel gas on one or both surfaces of the obtained molding, and firing the resulting slotted molding in a nonoxidizing atmosphere at 700 to 3000 °C. |