BIAXIALLY STRETCHED POLYPROPYLENE FILM FOR CAPACITORS

摘要

A biaxially stretched polypropylene film for a capacitor containing an isotactic polypropylene. The weight average molecular weight (Mw) of the isotactic polypropylene as measured by gel permeation chromatography (GPC) is 250,000 to 450,000, the molecular weight distribution Mw/Mn is 7 to 12 and Mz/Mn is 20 to 40, and the value of a difference obtained by subtracting a differential distribution value when the logarithmic molecular weight Log(M)=6 from a differential distribution value when Log(M)=4.5 on a molecular weight distribution curve thereof is 8% to 20%. The ultrathin biaxially stretched polypropylene film for a capacitor has superior heat resistance performance and withstands voltage performance.

主权项

1. A biaxially stretched polypropylene film for a capacitor containing an isotactic polypropylene, wherein
the weight average molecular weight (Mw) of the isotactic polypropylene as measured by gel permeation chromatography (GPC) is 250,000 to 450,000, the molecular weight distribution Mw/Mn is 7 to 12 and Mz/Mn is 20 to 40, and the value of a difference obtained by subtracting a differential distribution value when the logarithmic molecular weight Log(M)=6 from a differential distribution value when Log(M)=4.5 on a molecular weight distribution curve thereof is 8% to 20% with respect to the differential distribution value when Log(M)=4.5.