NONAQUEOUS ELECTROLYTE SECONDARY BATTERY SEPARATOR, NONAQUEOUS ELECTROLYTE SECONDARY BATTERY MEMBER, AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

As a nonaqueous electrolyte secondary battery separator which has excellent heat resistance and excellent battery performance, provided is a nonaqueous electrolyte secondary battery separator including a mixed layer which contains a heat-resistant resin and a porous base material that includes a polyolefin porous film, in the mixed layer, a weight ratio (W/W) between a weight Wof the heat-resistant resin and a weight Wof the porous base material being not less than 0.07.