| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a separator in which micro trenches for enhancing permeability of electrolyte can be formed precisely in the surface while reducing the depth and short circuit resistance, low internal resistance and permeability of electrolyte can be satisfied simultaneously. <P>SOLUTION: The separator comprises a micro porous film having an average pore size of 1 μm or less produced by a step for making a sheet of a material composition containing thermoplastic resin and plasticizer also serving as boring agent by melt molding, a step for thinning the sheet, a step for making the sheet porous by removing the plasticizer, and a step for forming a plurality of micro continuous trenches by embossing wherein thermoplastic resin is employed as a frame material and micro continuous trenches are provided with area rate of 5-60%. Following to the film making step, there are performed the thinning step, the step for making porous and the embossing step, and the sheet contains 20 mass% or more of inorganic powder in the embossing step. <P>COPYRIGHT: (C)2007,JPO&INPIT |
