| abstract |
An embodiment according to the disclosure of the present invention provides a method for manufacturing a composite membrane, the method including: heat treating a porous base material containing a thermoplastic resin, at a temperature T that satisfies the expression Tg + 60°C ≤ temperature T ≤ Tm (where Tg is the glass transition temperature [°C] of the thermoplastic resin and Tm is the melting point [°C] of the thermoplastic resin); adjusting the tensile stress of the porous base material in the machine direction to a range such that elongation of the porous base material is 2% or less, and coating one or both surfaces of the heat-treated porous base material with a coating liquid containing at least a resin and solvent to form a coating layer; and solidifying the coating layer to obtain a composite membrane having a porous layer which contains at least a resin, on one or both surfaces of the porous base material. |