Abstract: A process for producing a metallizable, sealable, biaxially stretch-oriented multi-ply film includes the steps of: providing melts of a predominantly polypropylene base layer, and first and second polyolefinic facing layers; co-extruding the melts through a flat film die, wherein the first and second polyolefinic facing layers are co-extruded on either side of the base layer; solidifying the co-extruded film by cooling; longitudinally stretching the co-extruded film at a temperature from about 120.degree. to 130.degree. C. in a ratio of from about 5 to 7:1; transversely stretching the co-extruded film at a temperature from about 160.degree. to 170.degree. C. in a ratio of from about 8 to 10:1; and corona-treating one facing layer of the co-extruded film which is metallizable. Each of the melts contains a calcium carbonate neutralizing agent having an absolute particle size of less than about 10 .mu.m, a mean particle size of less than about 0.1 .mu.m, a specific surface area of more than about 40 m.sup.

Abstract: The extruded, biaxially oriented dielectric film is composed of high-purity electrical film raw material. It is suitable as electrical insulating film in particular as a dielectric in an electrical capacitor, and exhibits improved dielectric properties for this prupose. The film comprises propylene polymers and stabilizers for the propylene polymers. The raw material of the film has an idealized thermo-oxidation temperature in the range from 260.degree. to 300.degree. C., preferably 260.degree. to 280.degree. C. The dielectric film has an idealized thermo-oxidation temperature of 250.degree. to 300.degree. C., in particular 250.degree. to 280.degree. C. The content of organic neutralizing agents, in particular calcium stearate, in the raw material is less than/equal to 100 ppm.

Abstract: A metallizable, sealable, biaxially stretch-oriented multi-ply film comprises a base layer essentially of polypropylene, a first polyolefinic facing layer and a second polyolefinic facing layer. All of the layers contain a neutralizing agent and a stabilizer against thermal degradation. The neutralizing agent is a calcium carbonate having an absolute particle size of less than 10.0 .mu.m, a mean particle size of less than 0.1 .mu.m, a specific surface area of more than 40 m.sup.2 /g and a whiteness of more than 90% and, the stabilizer comprises a phenolic stabilizer having a molecular weight of more than 1,000 g/mol. One polyolefinic facing layer contains an anti-blocking agent. In addition, a process for producing the metallizable multi-ply film is described, and its use as a packaging material is indicated.

Abstract: A biaxially-oriented film, suitable for use as an electrically insulating film, is disclosed. The film is composed of a highly-pure electrical film raw material based on polyolefins, in particular propylene polymers, and contains carbonate particles as a neutralizing agent. The carbonate particles preferably have an absolute particle size of less than 10 micrometers, a mean particle diameter of less than 0.1 micrometer, a specific surface area of more than 30 m.sup.2 /g and a degree of whiteness of more than 90%. The film is used as a dielectric in a capacitor and shows improved electrical properties.