Abstract: The application relates to a laminated porous film having a heat-resistant layer that is suitable for a separator for a non-aqueous electrolyte secondary battery having excellent cycle characteristics, and a coating liquid for forming the heat-resistant layer. A coating liquid containing a filler, a binder, and a solvent, wherein a hydrophilicity parameter A of the filler defined by formula (1) is 0.35 to 0.65: Hydrophilicity parameter A=BET1/BET2 ??(1) wherein, in formula (1), BET1: the specific surface area of the filler calculated using a BET method from a differential adsorption isotherm obtained by subtracting, from a first adsorption isotherm measured by adsorbing water vapor to the filler, a second adsorption isotherm; and BET2: the specific surface area of the filler calculated using a BET method from a differential adsorption isotherm measured by adsorbing nitrogen to the filler.

Abstract: The present invention relates to a laminated porous film having a heat-resistant layer that is suitable for a separator for a non-aqueous electrolyte secondary battery having excellent cycle characteristics, and a coating liquid for forming the heat-resistant layer. A coating liquid containing a filler, a binder, and a solvent, wherein hydrophilicity parameter A of the filler defined by formula (1) is 0.35 to 0.65: Hydrophilicity parameter A=BET1/BET2??(1) wherein BET1: the specific surface area of the filler calculated using a BET method from a differential adsorption isotherm obtained by subtracting, from a first adsorption isotherm measured by adsorbing water vapor to the filler, a second adsorption isotherm; and BET2: the specific surface area of the filler calculated using a BET method from a differential adsorption isotherm measured by adsorbing nitrogen to the filler.