Abstract: A polypropylene film which has a crystallite size of not more than 12.2 nm, the crystallite size being determined using Scherrer's equation from a full width at half maximum of the reflection peak from (040) plane of ? crystal measured by a wide-angle X-ray diffraction method, and a volume resistivity of not lower than 6×1014 ?·cm, the volume resistivity being calculated in accordance with equation I from a current value that is measured 1 minute after applying a voltage at a potential gradient of 200 V/?m in an environment at 100° C. Equation I: volume resistivity=[(effective electrode area)×(applied voltage)]/[(polypropylene film thickness)×(current value)].

Abstract: A biaxially stretched polypropylene film including a polypropylene resin and satisfying the following: (a) the crystallite size Sa, which is determined using the Scherrer equation from the full width at half maximum of the ?-crystal (040) plane reflection peak as measured by wide-angle x-ray diffraction after treatment for 200 hours at 105° C., is not more than 12.9 nm; and (b) the planar orientation coefficient ?Pa, which is calculated from the birefringence values ?Nyz and ?Nxz with respect to the thickness direction as determined by optical birefringence measurement after treatment for 200 hours at 105° C., is at least 0.013 (?Pa=(?Nyz+?Nxz)/2).

Abstract: A polypropylene film which has a crystallite size of not more than 12.2 nm, the crystallite size being determined using Scherrer's equation from a full width at half maximum of the reflection peak from (040) plane of ? crystal measured by a wide-angle X-ray diffraction method, and a volume resistivity of not lower than 6×1014 ?·cm, the volume resistivity being calculated in accordance with equation I from a current value that is measured 1 minute after applying a voltage at a potential gradient of 200 V/?m in an environment at 100° C. Equation I: volume resistivity=[(effective electrode area)×(applied voltage)]/[(polypropylene film thickness)×(current value)].

Abstract: A biaxially oriented polypropylene film containing a polypropylene resin, the film having a thickness of 1.0 to 3.0 ?m, and a molecular orientation coefficient ?Nx of 0.013 to 0.016, as calculated according to ?Nx=(?Nxy+?Nxz)/2 on the basis of a birefringence value ?Nxy in the slow axis direction with respect to the fast axis direction and a birefringence value ?Nxz in the slow axis direction with respect to the thickness direction, as measured via optical birefringence measurement.

Abstract: A biaxially stretched polypropylene film including a polypropylene resin and satisfying the following: (a) the crystallite size Sa, which is determined using the Scherrer equation from the full width at half maximum of the ?-crystal (040) plane reflection peak as measured by wide-angle x-ray diffraction after treatment for 200 hours at 105° C., is not more than 12.9 nm; and (b) the planar orientation coefficient ?Pa, which is calculated from the birefringence values ?Nyz and ?Nxz with respect to the thickness direction as determined by optical birefringence measurement after treatment for 200 hours at 105° C., is at least 0.013 (?Pa=(?Nyz+?Nxz)/2).