| abstract |
A resin sheet having a porous layered structure useful as an electrode separator for electric cells, said sheet comprising (a) an olefin resin, (b) a finely divided inorganic substance, and (c) at least one substance selected from the group consisting of (i) a water-swellable thermoplastic resin, (ii) a water-insoluble or difficultly water-soluble hydrophilic nonionic surface active agent, and (iii) a water-insoluble difficultly water-soluble hydrophilic anionic surface active agent, said sheet including fine pores arranged throughout its cross section in a plurality of layers, at least some of them forming open cells. |