| abstract |
PROBLEM TO BE SOLVED: To provide a microporous polyolefin membrane having a relatively large pore size, a sharp pore size distribution, and excellent permeability, which is used for applications such as water treatment and microfiltration membranes. SOLUTION: An ultrahigh molecular weight polyolefin (A) having a weight average molecular weight of 5 × 10 5 or more and a weight average molecular weight of 5 × 10 5 are provided. Less than a mixture of polyolefins (B), (B) / A solution consisting of 5 to 40% by weight of a polyolefin composition having a weight ratio of (A) of 0.2 to 20 and 95 to 60% by weight of a solvent is prepared, the solution is extruded from a die, and the film is taken out by a cooling roll. A method for producing a microporous polyolefin membrane, which comprises adjusting the cooling conditions in a method for producing a microporous polyolefin membrane by removing the solvent remaining in the film after forming and drying. |