Polyolefine microporous film and its production manner

摘要

PURPOSE: To provide a finely porous polyolefin film excellent in drawability, pore size distribution sharpness, etc., useful for battery separators, electrolytic capacitors, etc., consisting of a polyolefin having each specific pore characteristics, breaking strength and molecular weight characteristics. ;CONSTITUTION: The porous film consisting of a polyolefin having the following characteristics: (1) porosity: 35-95%; (2) mean penetrated pore diameter: 0.001-0.02μm; (3) breaking strength (15mm width): ≥0.2kg; (4) pore size distribution (max. pore diameter/means penetrated pore diameter): ≤1.5; (5) content of the components ≥7×10⁵ in molecular weight: ≥1wt.%; and (6) weight-average molecular-weight/number-average molecular weight: 10-300. This porous film can preferably be obtained by the following process: a solution composed of 10-50wt.% of a polyolefin having the above-mentioned molecular weight characteristics and 50-90wt.% of a solvent is first prepared and then extruded through a die and cooled into a gel-like composition, which is then heat set at a temperature between the crystal dispersion temperature and the melting point of the polyolefin followed by drawing at a temperature not higher than the melting point plus 10°C and then desolvation.;COPYRIGHT: (C)1994,JPO&Japio