| abstract |
The present invention provides a polyolefin microporous film in which it is possible to prevent degradation in the air permeability of a separator due to high-pressure press-working during the procedure of manufacturing a cell, the polyolefin microporous film having exceptional compression resistance. In addition, using this polyolefin microporous film makes it possible to provide a cell having exceptional cycle characteristics. A polyolefin microporous film in which the rate of change in the air permeation resistance after 5 minutes of heat-compression at a temperature of 90°C and a pressure of 5.0 MPa is 50% or less, and the rate of change in the film thickness after 5 minutes of heat-compression at a temperature of 90°C and a pressure of 5.0 MPa is 10% or less in relation to the film thickness of the polyolefin microporous film before the heat-compression. |