| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing the subject mambrane high in strength, useful as a separator for batteries, etc., at a low cost in high productivity, by heating and drawing a solution of an ultrahigh molecular weight polyolefin. SOLUTION: A solution comprising 10-80% of a polyolefin composition containing >=1wt.% of an ultrahigh molecular weight polyolefin having >=7×10<5> weight-average molecular weight and 90-20wt.% of a solution is prepared. The solution is extruded from a die having 0.5-2.5mm die gap at 120-250 deg.C die temperature into a sheet shape, drawn at a draw ratio of 110-5,000% while cooling to form a gelatinous molding. The gelatinous molding is heated and drawn at least in the uniaxial direction at 5-50 times and then the residual solvent is removed. Preferably the solution is extruded from a die having 1.5-2.5mm die gap at 160-230 deg.C die temperature into a sheet shape and drawn at 110-1,000% draw ratio while cooling to form a gelatinous molding. |
