Abstract: A main object is to provide a biaxially stretched polypropylene film for capacitors that has high voltage resistance at high temperatures and excellent dielectric breakdown properties and that can be formed into an ultrathin film. Furthermore, a capacitor obtained by using the biaxially stretched polypropylene film for capacitors described above is provided. The biaxially stretched polypropylene film for capacitors, includes a polypropylene resin, and the film has a spacing value of (040) face of ?-crystal measured by X-ray diffraction of 0.525 to 0.530 nm.

Abstract: A polyolefin microporous membrane is capable of achieving a low shutdown temperature while keeping air permeation resistance sufficiently low, and a method produces the polyolefin microporous membrane. The polyolefin microporous membrane has, when a temperature is raised to 230° C. at a temperature rise rate of 10° C./min in differential scanning calorimetry (DSC), a ratio of a melting heat quantity (?H<Tm0) of equal to or larger than 95% at temperatures lower than an equilibrium melting point of polyethylene, relative to 100% of the total melting heat quantity (?Hall).

Abstract: A main object is to provide a biaxially stretched polypropylene film for capacitors that has high voltage resistance at high temperatures and excellent dielectric breakdown properties and that can be formed into an ultrathin film. Furthermore, a capacitor obtained by using the biaxially stretched polypropylene film for capacitors described above is provided. The biaxially stretched polypropylene film for capacitors, includes a polypropylene resin, and the film has a spacing value of (040) face of ?-crystal measured by X-ray diffraction of 0.525 to 0.530 nm.