MULTILAYER MICROPOROUS MEMBRANE, METHOD FOR PRODUCING SAME AND BATTERY SEPARATOR

There is provided a laminated microporous film having an excellent balance between air permeability and film rupture temperature obtained by laminating a first microporous layer comprising a first resin composition and a second microporous layer comprising a second resin composition having a lower melting point than the first resin composition, wherein the first microporous layer has a melt viscosity ηof 10,000 Pa·s or higher, and a ratio η/ηof the melt viscosity ηto a melt viscosity ηof the second microporous layer is 0.01 to 10.