| 摘要 |
Provided is a method for producing a propylene-based resin microporous film capable of forming a high-performance lithium ion battery. The method for producing a propylene-based resin microporous film includes an extrusion step of melt-kneading a propylene-based resin in an extruder, and extruding the resin to obtain a propylene-based resin film; a first stretching step of uniaxially stretching the propylene-based resin film at a surface temperature of -20 to 100°C; a second stretching step of repeating, a plurality of times, a stretching basic step in which the propylene-based resin film after the first stretching step is uniaxially stretched at a surface temperature that is equal to or lower than a temperature lower than the melting point of the propylene-based resin by 10 to 100°C, wherein between successive stretching basic steps, the stretching ratio in the forward-side stretching basic step is adjusted so as to be lower than that of the backward-side stretching basic step; and an annealing step of annealing the propylene-based resin film after the second stretching step. |
