Processors of multilayer blown film know it is critical to keep precise control of the thickness of the various layers of a film's structure, especially the costly barrier-material layers. A new measuring system is claimed to enable processors to measure these layers during processing, at output rates up to 450 m/min.
The new system was developed by researchers at two German institutes, the IKV (Institute for Plastics Processing) and the Fraunhofer Institute for Laser Technology, both based in Aachen. Measuring the layers in multilayered film, during blown-film extrusion, has not been possible—or at least not with any great degree of accuracy—with barrier layers in these structures often as thin as 1-20 µm. The barrier needs to be guaranteed over the entire web surface, which means processors often are pushed to use more of the barrier material—EVOH, for instance—than may actually be necessary. With this new thickness gauge, it could be that processors can save significant amounts of material.