Separator material for alkaline secondary battery, method for producing the same, and separator for alkaline secondary battery

摘要

A separator material of the present invention is a sulfonated nonwoven that comprises a polyolefin ultra-fine short fiber having a fineness of less than 0.5 dtex and other polyolefin short fiber(s). The other polyolefin short fibers include a polyolefin thermal bonding short fiber. At least a portion of the polyolefin thermal bonding short fiber is flattened to bond the component fibers together. The nonwoven has a specific surface area in a range of 0.6 m2/g to 1.5 m2/g and satisfies the following ranges. (1) A ratio (S/C)E of the number of sulfur atoms (S) to the number of carbon atoms (C) in the nonwoven, as measured by Electron Spectroscopy for Chemical Analysis (ESCA), is in a range of 5x10-3 to 60x10-3. (2) A ratio (S/C)B of the number of sulfur atoms (S) to the number of carbon atoms (C) in the nonwoven, as measured by a flask combustion technique, is in a range of 2.5x10-3 to 7x10-3. (3) A ratio (S/C)E/(S/C)B (depth of sulfonation) of (S/C)E to (S/C)B is in a range of 1.5 to 12. Thus, a separator material that has a high level of self-discharging performance when charge and discharge are repeatedly performed, a high level of process performance when assembling a battery, and a high level of short-circuit withstand capability; a method of producing the same; and an alkali secondary battery separator, are provided. IMAGE