Patent ID: 7414004

Claim:
A method for producing a gas diffusion layer for a fuel cell comprising a first step of: impregnating a conductive porous substrate made of conductive carbon fiber cloth or conductive carbon fiber felt with a first dispersion containing a first fluorocarbon resin having thermoplasticity; and baking said conductive porous substrate at a first baking temperature of not less than the melting point of said first fluorocarbon resin and less than the decomposition temperature of said first fluorocarbon resin to enhance the rigidity of said conductive porous substrate, and after said first step, a second step of: applying a shearing force to a second dispersion containing conductive carbon particles and a second fluorocarbon resin having thermoplasticity; applying said second dispersion onto one surface of said conductive porous substrate; and baking said conductive porous substrate at a second baking temperature of less than the melting point of said second fluorocarbon resin to form a conductive water repellent layer, wherein, in said first step, said first fluorocarbon resin is at least one selected from the group consisting of tetrafluoroethylene-hexafluoropropylene copolymer and tetrafluoroethylene-perfluoroalkylvinylether copolymer, and in said second step, said second fluorocarbon resin is polytetrafluoroethylene.