Development of a method for a realistically and reproducible contamination of polymer melt filters
Meilwes Peter (1)*, Schöppner Volker (1)
(1) University of Paderborn - North Rhine Wesfalia - Germany
In the field of polymer processing, the extrusion is one of the most common processing methods. Not
only in the processing of recycled materials, also when using virgin polymers there can be
contaminations during the storage or processing of the material. This may adversely affect the melt
quality and by this also the quality of the final extrusion product. Examples for possible
contaminations are metal particles which are caused by wear and tear of the extruder, or degradation
products of the processed material itself.
As a result of increasing demands on the quality of extrusion products, especially in the field of fiber
and film extrusion, filtration of polymer melts is widely used and state of the art today. To remove
unwanted debris out of the melt, different metal filter media is used. Some examples for typical filter
media are different kinds of wire mesh, filters out of nonwoven metal fibers or sintered metal powder
discs. Using this filter media, it is possible to remove foreign particles like solid particles, as well as
soft components, the so called “gels” from the melt. This ensures a high quality extrusion result.
In order to compare the filtering effect of different filter media and to assess the contamination and
selective filtration it is necessary to develop a possibility for reproducibly rapid contamination of
filter materials. In this work this should be elaborated as part of the PET processing. For this, a real
filter contamination is analyzed. After this a definition of an adequate substitute dirt is effected. The
focus is both on solid particles, as well as on gel contamination. With this it is possible to generate
realistic and reproducible filter soiling so that pressure rise curves can be generated in order to
compare the behavior of different filter media in the extrusion process.