| abstract |
A polyethylene microporous membrane having a thickness of at most 10 mu m, a breaking strength of at least 200 kg/cm2 and a porosity of at least 30% is produced by heating and dissolving polyethylene having a weight average molecular weight of at least 5x105 in a solvent, forming a gel sheet from the resulting solution, subjecting the gel sheet to a solvent removal treatment to adjust the amount of the solvent in the gel sheet to 10 to 80% by weight, heating and stretching the sheet and then removing the residual solvent therefrom. |