SEPARATOR MATERIAL FOR FUEL CELL AND PROCESS FOR PRODUCING THE SAME

摘要

A separator material for fuel cells which has high electrical conductivity, high gas impermeability, large breaking strain, and excellent strength properties; and a process for producing the material. The separator material for fuel cells comprises a graphite/cured-resin molding obtained by bonding with a thermosetting resin sphered natural-graphite particles which have been obtained by sphering flaky natural graphite having an average particle diameter of 1-50 µm by the high-speed flow impact method and which have an average particle diameter of 20-100 µm, a particle density as measured in water of 2 g/cm³ or higher, a compressive resilience, as measured after pressing at a pressure of 50 MPa, of 120% or lower, and a density during the compression of 1.9 g/cm³ or higher. The process is characterized by producing sphered natural-graphite particles having these properties, kneading the sphered natural-graphite particles together with a thermosetting resin in such amounts that the proportion of the graphite particles to the solid component of the resin is from 90/10 to 65/35 by weight, subsequently drying the mixture, pulverizing it to produce a molding powder, packing the molding powder into a mold bearing grooves/ridges serving to form a gas channel, and molding it by hot pressing at a temperature of 120°C or higher and a pressure of 20-100 MPa.