| abstract |
Provided are: a porous membrane that is able to simultaneously attain superior electrical performance and superior mechanical strength, and furthermore of which the surface layer on both sides have the same pore characteristics; and a method for producing the porous membrane. The porous membrane comprises an polyethylene resin having a weight average molecular weight of at least 300,000 and less than 500,000, the micropores are oriented in a multi-layered structure, the pores having a relatively large size compared to the surface layer on both sides are distributed in the central layer, and the surface layer on both sides have the same pore characteristics. The method for producing the porous membrane contains: a step for obtaining a mixture of liquid phase paraffin wax and solid phase paraffin wax; a step for adding the wax mixture to a polyethylene resin; and a step for extracting the wax mixture by immersing in an organic solvent. |