| 摘要 |
<p>PROBLEM TO BE SOLVED: To easily provide a separator wherein oxygen gas occurring at overcharge with an alkali secondary battery passes well, the internal pressure of battery is hard to rise, a cycle life is long, being of high rigidity though with less thickness, and a self-discharge suppressing function is provided, with good capacity retention. SOLUTION: The laminating-type an alkali battery separator satisfies all following conditions (1)-(4), to allow both lamination and sulfonation while strength of a nonwoven fabric is improved: (1) a nonwoven fabric comprising a specified polypropylene resin containing less low melting-point component is used; (2) the nonwoven fabric containing thin fiber and the nonwoven fabric containing thick fiber are sulfonated with a liquid sulfonating agent at a constant high temperature; (3) the non-woven fabric containing thick fiber and that containing thin fiber are pressurized at a high temperature; (4) two kinds of nonwoven fabrics in which a limit viscosity difference is within a constant range, with no difference, while a sufficient difference is provided for fiber thickness are laminated.</p> |
