DISPERSION OF ION-EXCHANGE POLYMER, PROCESS FOR PRODUCING THE SAME, AND USE THEREOF

摘要

An ultrasonic vibration or shear force is applied to an ion-exchange polymer dispersion comprising a dispersion medium and evenly dispersed therein an ion-exchange polymer comprising a fluoropolymer having sulfo groups to thereby increase the viscosity of the dispersion as measured at 25°C and a shear rate of 10 (1/s) 2- to 2,000-fold. Thus, a thickened ion-exchange polymer dispersion is produced. When this dispersion is for film formation, an ion-exchange membrane is obtained which has an even small thickness, has high strength, is free from cracks, and has a stable degree of swelling in water or water vapor. When a coating fluid comprising this dispersion and a particulate catalyst comprising a carbon support and catalyst metal particles deposited thereon is prepared and applied to a substrate to form a layer and this layer is used as a catalyst layer for at least either of a cathode and an anode so as to be disposed adjacently to an ion-exchange membrane, then a united film electrode assembly is produced. Since the catalyst layer has high strength, few defects, and excellent smoothness, the united film electrode assembly is useful in high-performance solid polymer type fuel cells.