Abstract: The invention relates to a biaxially oriented polyester film which has very good optical properties and good processing behavior and which after it has been metallized or coated with oxidic materials exhibits a high oxygen barrier and which is built up from at least one base layer B and at least one layer A applied on top of this base layer, this layer A having a number N of elevations/protrusions per mm2 of film surface area which is related to their respective heights h and diameters d by the following equations: log N/mm2<Ah−Bh*log h/&mgr;m, 0.01 &mgr;m<h<10 &mgr;m  (1) wherein Ah=1.4; Bh=2.5 log N/mm2<Ad−Bd*log d/&mgr;m, 0.4 &mgr;m<d<10 &mgr;m  (2) wherein Ad=3.4; Bd=2.4.

Abstract: The invention relates to a biaxially oriented polyester film which has at least three layers and has better optical properties than films of the prior art together with very good processing performance, and, after it is metalized or coated with oxidic materials, is a good barrier to oxygen, and which is built up on each side from at least one base layer B and outer layers A and C applied to this base layer, where these outer layers have a defined number of elevations of a defined height and diameter. The invention further relates to the use of the film and to a process for the production thereof.

Abstract: A device for laying a film 3 emerging from a slot die 2 onto a take-off roll 1 has at least one electrode that is arranged parallel to and at a short distance from the surface of the take-off roll 1 and to which electric voltage in the range from 4 to 12 kV is applied. This electrode is, for example, a metal strip 4, which has a tapering strip edge 6 this is directed toward the surface of the take-off roll 1. In addition to this metal strip 4, one or a plurality of electrodes 5, 8 and 16 are arranged at a distance from the surface of the take-off roll. These additional electrodes have applied to them an electric voltage whose magnitude is the same as or different from that applied to the metal strip 4. As a result, additive electric fields to the electric field of the one metal-strip electrode are formed.

Abstract: The invention relates to a coextruded heat-sealable polyester film having at least one base layer and at least one heat-sealable outer layer, wherein this heat-sealable outer layer comprises a copolymer which contains from 5 to 95% by weight of ethylene 2,6-naphthalate units.

Abstract: In a filter apparatus 1, a central filter rod 6 is arranged in the interior 14 of a filter housing 2, the diameter d of which filter rod tapers in the direction of flow of the plastic melt. On the filter rod 6 are arranged filter discs 7 which are parallel to one another and have outer and inner diameters of equal size. The filter apparatus 1 operates as a continuous-flow filter apparatus in which the plastic melt flows in via an intake 4 and flows out via an outlet 5. A filter housing wall inner surface 3 tapers in the direction of flow of the plastic melt, so that a gap width h.sub.a (x) between a filter disc outer rim 8 and the filter housing wall inner surface 3 decreases in the direction of flow of the plastic melt.

Abstract: The invention relates to a biaxially oriented polyester film having a roughness, on at least one film surface, of R.sub.z greater than 1.0 .mu.m (Ra is greater than 0.1 .mu.m), a dielectric strength (AC) greater than 220 kV/mm (the DC dielectric strength is greater than 500 kV/mm) and a migrating fraction in the film of less than 18 .mu.S/cm based on a mass of added particles in a polyester volume of 100 cm.sup.3. The film is particularly suitable for oil-impregnated capacitors.