Extrusion International 5-2022

82 Extrusion International 5/2022 PROCESSING Compounding of Recycling Plastics Opens Up New Opportunities More andmore companies are looking for new ideas as to how recycling plastics can be incorporated into end products for consumers and technical components for industry. As a result, compounding is comingmore into focus – provided that process stability, high availability and durability of the machines used in the compounding process can be assured. A glance at the shelves in the super- market is enough – even today you can already find a large number of packagings that advertise a high recycling plastic content, and this share is set to increase even further. It is not only the large manufacturers of goods and articles for the ultimate consumer who are changing over or re-evaluating their processes, but also many other industries. But changing over a process to en- able the use of recycled materials is anything but simple. In the meantime, it has become possible to produce customized recycling plastics even for high-grade applications by adding ad- ditives, fillers or reinforcing materials such as talcum or chalk (CaCO3), glass fibers or master batch pigments. In view of the fluctuating quality of the input material, however, the know- how about material properties, wear protection and process stability is more important than ever when it comes to the compounding of recycling plastics. Only then can the property profile of the end product be maintained with- out compromising quality. In this respect, raw materials based on recycled material no longer differ much from virgin material in terms of their properties. However, this does have an impact on the pumps, filters and pelletizing systems required for the compounding process. Ultimately different compositions, residual mois- ture contents and viscosities are the order of the day with recyclates, and various contaminants further compli- cate the compounding process. To give just one example: For cost reasons, recycled material is often mixed with fillers, especially talcum or chalk. They can often account for up to 60 percent of the material. The mineral filler has a wear-enhancing effect. Furthermore, higher contami- nation levels and thus larger particle sizes are involved. Extremely resilient pumps and melt filters are therefore required. This makes it all the more important to have well-matched components in the entire process. Each component combines with the next Maag supplies complete solutions for the compounding process. Here – from melt conveying and filtration to pelletizing or grinding and drying through to the control system – all the components combine seamlessly with one another to create and efficient production process. The know-how of the entire Maag family with the prod- uct brands Automatik, Ettlinger, Gala, Maag, Reduction, Scheer and Xantec goes into the process. These individu- al elements are brought together into one system, resulting in a complete system downstream of the extruder. The carefully combined unit with the Xantec control concept has coordi- nated interfaces. It ensures optimum process monitoring and can even be extended to the extruder control sys - tem and the dispensing, i.e. to the en- tire recycling line. Vast system know-how Long service lives, especially when working with recyclates and fillers, are achieved not only by innovative mate- rials and surface know-how, but also by the way the system is operated. To achieve fast start-up and shutdown cycles of processing and compounding extruders, and minimize the load on them, the pressure of the plastic melt is generated by a gear pump. Only with a constant pressure and volume in the process can pellets of the highest qual- ity be continuously produced. In the Maag melt pump, on the other hand, the material is only briefly pressurized and is subject to very little shearing. The reason for this is that the MAAG Group Recycling Systems Ettlinger high performance melt filter ERF1000