Method for dissolving and degassing polymer, and method for producing porous film

摘要

A method for dissolving and degassing a polymer is described, including a dissolution/degassing step. In the dissolution/degassing step, a mixture containing the polymer and a solvent is agitated, in a pressure-reduced condition with a gauge pressure of −50 to −90 kPa and at a temperature lower than the boiling point of the solvent in the pressure-reduced condition but higher than the freezing point of the same, to dissolve the polymer and simultaneously degas the polymer solution, so as to obtain a polymer solution.

主权项

1. A method for producing a porous film, comprising:
a dissolution/degassing step, comprising agitating a mixture containing the polymer and a solvent, in a pressure-reduced condition with a gauge pressure of −50 to −90 kPa and at a temperature lower than a boiling point of the solvent in the pressure-reduced condition but higher than a freezing point of the solvent, to dissolve the polymer and simultaneously degas a solution of the polymer, so as to obtain a polymer solution; and a solidification step for solidifying the obtained polymer solution in a solidification liquid to form the porous film, wherein after the pressure-reduced condition with the gauge pressure of −50 to −90 kPa is achieved in the dissolution/degassing step, a pressure reduction means is stopped while the pressure-reduced condition is maintained, and the mixture is agitated at the temperature lower than the boiling point of the solvent in the pressure-reduced condition but higher than the freezing point of the solvent, wherein the dissolution/degassing step is performed at a temperature of 50° C. to 90° C., and wherein the agitation is performed for 60 to 240 minutes.