| 摘要 |
PURPOSE:To make a film endure collapse even when an anode with a roughened surface is pushed against it when it is used as an electrolyte separator of, e.g., an electrolytic capacitor and to prevent an increase in a short circuit ratio or in an equivalent series resistance, by optimizing the mean pore diameter, porosity and Young's modulus of compression of a polyolefin film. CONSTITUTION:This microporous polyolefin film has a mean pore diameter of 0.05-5mum, a porosity of 50-85% and a Young's modulus of compression of 0.2kg/mm<2> or above. As said polyolefin, polypropylene of an isotactic index of 93% or above and an intrinsic viscosity of 1.2-3.3dl/g is desirable. A polypropylene having a melt crystallization temperature of 106 deg.C or above is particularly desirable among such polypropylenes. |
