White goods mainly use polypropylenes with different fillers such as talc (PP-T), chalk (PP-K) or glass fiber (PP-GF). This means that in the sorting process, it is not enough to recognize and separate the PP as a polymer only, it is even necessary to be able to look “deeper” into the material. Of course, many steps were necessary from the first tests since 2019 to the current production status, as Innovation Manager Daniel Forstner knows best. He played a key role in developing the "filled PP" research project and leading it to implementation. "The technological difficulty is primarily in separating the mixed raw material - a wild mixture of plastics, which also contains the polypropylene with its various fillers - by type. Our colleague Cornelia Wieser carried out intensive basic research in the MGG Metran laboratory and examined a huge number of samples in order to define the distinguishing features of PP-K, PP-T and PP-GF. After completing her work, she was even able to identify the material differences by the sound of the plastic."
These analyzed sample pieces were an important part of the entire project, as they allowed the MGG team to decide whether existing equipment in the Müller Guttenbrunn Group would be suitable for separating the materials. Or, whether equipment needed to be reworked or it was necessary to contact machine manufacturers to develop completely new sorting solutions. The main challenge turned out to establish a proper sorting by those pieces of filled PP that contain only 10% filler or less and are also usually very dirty.
However, Höggerl and Forstner do not want to reveal how MGG Polymers has now managed to actually separate the individual fractions in detail: "What we can say is: The plastic parts must ultimately be sorted with the aid of sensor-based machinery. This makes the Müller-Guttenbrunn Group a pioneer once again, and we can be proud of that!"