Every crisis presents an opportunity. In the middle of a crisis, BASF has invested in improving the quality and efficiency of its ABS production, with advanced polymer melt filtration systems from Gneuss Kunststofftechnik GmbH.
For BASF to improve the quality of its ABS, it was necessary to reduce filtration fineness. However: with a conventional screen changer, finer filtration automatically means shorter time intervals between screen changes.
Many ABS extrusion lines are still equipped with conventional screen changers, with which finer filtration automatically means more frequent production disturbances.
With conventional screen changers, every screen change involves diverting material to “off grade” during and for some time after a screen change as pressure variations lead to variations in the yellowness of the material. Further, burnt material from the dead spots in the screen changer and burnt material on surfaces is introduced into the final product. For every screen change, around 15 minutes of production is sold off at a low price as “off grade” thereby cancelling out the product price premium and market advantages offered by finer filtration.
The Gneuss RSFgenius used in this case completely avoids the problem of quality fluctuations during filter changes. Thanks to its Rotary Disc technology, there are neither pressure variations nor burnt particles in the polymer. The result: a much improved yield of consistently high quality material. The RSFgenius is equipped with a unique self-cleaning system. Even with finer filter elements, the time interval between changes is measured in weeks, keeping the level of operator attention and the cost for filter elements to a minimum.
BASF manufactures ABS using underwater pelletising equipment. This provides an excellent pellet shape however at the expense of a relatively high polymer back pressure. (Another attraction of a screen changer which does not create pressure spikes). In close coordination with the customer, Gneuss engineered a tailor made package including a booster melt pump and control system.