The invention relates to a method for preparing perfluorocarboxylic acid
ion membranes, which is characterized in that the method comprises the following steps: (1) dissolving perfluorocarboxylic acid resin into a
solvent for forming a uniform perfluorocarboxylic acid resin solution A; (2) adding materials with
low melting point and
high density into a heatable container, heating the container for dissolving the materials, and forming uniform liquid B in the container; (3) preheating the perfluorocarboxylic acid resin solution A and pouring the perfluorocarboxylic acid resin solution A onto the surface of the liquid B protected by
nitrogen gas so that a
thin layer solution is formed on the surface of the liquid B through
casting; (4) heating the liquid B, then carrying out program temperature reduction, and continuously introducing the
nitrogen gas for protection in the whole process; and (5) evaporating most or all of the
solvent in the perfluorocarboxylic acid resin solution A to obtain the perfluorocarboxylic acid
ion membrane on the surface of the liquid B. The perfluorocarboxylic acid
ion membrane prepared by the invention can be applied to composite
layers of
sodium hudroxide use ion membranes, and has the advantages of uniform thickness, difficult bubble generation and stable performance, and the invention provides reliable
carboxylic acid layer ion membranes for producing the
sodium hudroxide use ion membranes.