| abstract |
A porous film having a uniform pore size and formation density is continuously produced. A cast film 22 is formed by casting a solution containing an organic solvent and an amphiphilic compound on a casting belt 21. When ΔT is a value obtained by subtracting the surface temperature TS of the cast film 22 from the dew point TD around the cast film 22, dew is formed under the condition of 3 ° C. ≦ ΔT ≦ 30 ° C. to form water droplets on the cast film 22. To do. Immediately after this, water droplets are grown under conditions of 0 ° C. <ΔT ≦ 10 ° C., and the organic solvent is evaporated from the cast film 22. Thereafter, water droplets are evaporated from the cast film 22 under the condition of TD <TS. [Selection] Figure 4 |