A BIAXIALLY ORIENTED TWO-LAYER COPOLYESTER FILM FOR CAPACITOR DIELECTRIC USE

摘要

The present invention comprises a two-layer biaxially oriented copolyester film useful for capacitor dielectrics. Such films have good winding characteristics, slipperiness, good mechanical properties, and excellent thermal stability. The two-layer biaxially oriented copolyester film comprises: (a) a two-layer biaxially oriented copolyester film, wherein at least one layer essentially consists of PENBB and which two-layer biaxially oriented copolyester film has a melting point sufficient to withstand a thermal treatment of about 260 DEG C for about 10 seconds or higher; and (b) an effective amount of one or more particulate materials uniformly dispersed in at least one layer of said two-layer biaxially oriented copolyester film sufficient to provide slip and good winding characteristics, whereby the average surface roughness Ra of one of said layers is 10 nm.