| 摘要 |
The present invention relates to a cation exchange membrane including a fluorine-containing polymer which includes tetrafluoroethylene units, and perfluoroethylene units having carboxylic acid ion exchange groups. The melt index (a) of the fluorine-containing polymer obtained by methyl esterifying the carboxylic acid ion exchange groups, said melt index (a) being measured under conditions in which the temperature is 270˚C, the load is 2.16 kg, and the orifice internal diameter is 2.09 mm, is 3-50 g/10 min. Furthermore, the melt index (a), and the melt index (b) of the fluorine-containing polymer obtained by methyl esterifying the carboxylic acid ion exchange groups, said melt index (b) being measured under conditions in which the temperature is 260˚C, the load is 2.16 kg, and the orifice internal diameter is 2.09 mm, satisfy the relationship represented by formula (1), namely (a-b)/(270-260) ≤ 0.027×a+0.19. |
