Microporous membrane winding and method for manufacturing the same

摘要

A microporous membrane winding includes a microporous membrane wound around a core. The core has an outer diameter of 5 inches or greater, and has an outer surface with a surface roughness of 3.0 μm or less. A microporous membrane that is excellent in thickness uniformity and is favorably used as a separator for a lithium-ion secondary battery can be obtained from the microporous membrane winding.

主权项

1. A microporous membrane winding comprising a core of cylindrical shape and a microporous membrane comprised of polyolefin wound around the core having outermost layer and an innermost layer, wherein the core has an outer diameter of 5 inches or greater, and 20 inches or less and a surface roughness of the core is 3.0 μm or less and 0.01 μm or greater, and wherein the thickness of the outermost layer differs from the thickness of the innermost layer by a factor of 1.5 or less.