| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a cut-off three-layer battery separator that has satisfactorily small thickness, sufficient strength and relatively low cut-off temperature. SOLUTION: This separator is composed of a first and third fine porous strength layers 12, 16 interposing a second cut-off layer 14 and the cut-off layer 14 is a fine porous film made by means of a particle stretching method. This manufacturing method comprises a process to form a fine porous cut-off layer film by means of the particle stretching method, a process to form a fine porous strength layer film and a process to bond the films together as a three-layer battery separator such that the first and third films become strength layers and the second film becomes the cut-off layer formed by means of the particle stretching method.</p> |
