abstract |
The present invention provides a polyolefin microporous membrane and a production method therefor that make it possible to achieve a low shutdown temperature while keeping air resistance sufficiently low. When the temperature of this polyolefin microporous membrane is increased by differential scanning calorimetry (DSC) to 230℃ at a rate of 10℃/min., if the total heat of fusion (ΔH a11 ) is 100%, the fraction thereof that is the heat of fusion (ΔH <Tm0 ) below the equilibrium melting point of polyethylene is 95% or higher. |