| abstract |
(57) [Problem] To provide a polyolefin microporous membrane having a low heat shrinkage rate and an excellent balance of physical properties. SOLUTION: It is composed of a polyolefin (A) having a weight average molecular weight of 500,000 or more or a polyolefin composition (B) containing the polyolefin, and has an air permeability of 1200 seconds / 1. Over 2000cc / 100cc or less and T A microporous polyolefin membrane having a heat shrinkage in the direction D of 2.0% or less, and a method for producing the same. |