| abstract |
Multilayer microporous polyolefin membrane having at least three layers, comprising first microporous layers made of a polyethylene resin to constitute at least both surface layers, and at least a second microporous layer, comprising a polyethylene and polypropylene resin and is disposed between both surface layers, including the polyethylene resin in the first microporous layers an ultra-high molecular weight polyethylene, the heat of fusion (DHm) of the polypropylene measured by differential scanning calorimetry of 90 J / g or more, and the content being of polypropylene in the second microporous layer of 50% by mass or less on the basis of 100% by mass of the total polyethylene and polypropylene resin. |