A thickened ion exchange polymer dispersion is obtained by applying ultrasonic vibration or a shearing force to an ion exchange polymer dispersion having a fluorinated polymer having sulfonic acid groups as an ion exchange polymer uniformly dispersed in a dispersion medium so that the viscosity of the dispersion at 25°C at a shear rate of 10 (1/s) increases 2-2000 times in a thickening step. When formed into a membrane, the dispersion can forms an ion exchange membrane having a uniform and small thickness, high strength, which is free from cracking and shows constant swelling in water and steam. Further, a layer formed by applying a coating solution containing this dispersion and a catalyst powder comprising catalyst metal particles and a carbon support loaded with the catalyst metal particles to a substrate can be used to prepare a membrane-electrode assembly as a catalyst layer for at least one of the cathode and the anode by providing the catalyst layer adjacently to an ion exchange membrane. Because the catalyst layer is highly strong, has few defects and is excellently smooth, a high-performance membrane-electrode assembly for solid polymer electrolyte fuel cells can be obtained.
一种增稠的离子交换聚合物分散体是通过对均匀分散在分散介质中的具有
磺酸基团的
氟化聚合物作为离子交换聚合物的离子交换聚合物分散体施加超声波振动或剪切力,使其在 25°C、剪切速率为 10 (1/s) 时的粘度在增稠步骤中增加 2-2000 倍而得到的。当形成一层膜时,分散体可以形成一层离子交换膜,该膜厚度均匀,厚度小,强度高,在
水和蒸汽中不会开裂并显示出恒定的膨胀性。此外,将含有该分散液和由催化剂
金属颗粒组成的催化剂粉末以及装有催化剂
金属颗粒的碳载体的涂层溶液涂在基底上形成的层,可用于制备膜电极组件,作为阴极和阳极中至少一个的催化剂层,方法是将该催化剂层提供给离子交换膜。由于催化剂层强度高、缺陷少且非常光滑,因此可获得用于固体聚合物电解质燃料电池的高性能膜电极组件。