| abstract |
The present invention provides a method for producing a composite film. The embodiment of the present invention has the following steps: a step of heat-treating a porous substrate containing a thermoplastic resin at a temperature T of the following formula, Tg + 60 ° C ≦ temperature T ≦ Tmn(Tg represents the glass transition temperature [°C] of the thermoplastic resin, Tm represents the melting point [°C] of the thermoplastic resin); and the tensile stress in the mechanical direction of the porous substrate is adjusted to 2% of the elongation of the porous substrate. In the following range, a coating liquid containing at least a resin and a solvent is applied to one surface or both surfaces of the porous substrate after heat treatment to form a coating layer, and the coating layer is solidified to obtain the porous material. A step of having a composite film of at least a porous layer containing a resin on one or both sides of the substrate. |