Setting the Stage for the Future: Modernization of Compounding Lines for Processing Higher Proportions of Recyclate

Technologically, the stage is already set to achieve this goal. Our twin screw compounder makes it possible to process plastic recyclates into high-quality plastics. We possess the necessary comprehensive process expertise for this task. And we are happy to advise you as to how you can modernize your system so that processing larger proportions of recyclate is possible on your existing compounding line. We can offer you a balanced package of measures, while taking the needs of the entire process into account.

First, let’s take a look at feeding: secondary raw materials are usually very heterogeneous in nature and feeding them accurately is a major challenge. Feeders must be able to reliably introduce materials with inconsistent bulk densities into the process. One solution to this challenge can be our Coperion K-Tron Smart Weigh Belt (SWB) feeder. The SWB feeders are relatively simple, extremely reliable gravimetric feeding devices that ensure high accuracy. They can feed large volumes of bulk materials reliably, even materials with varying bulk densities and flow properties. They weigh the bulk material as it passes through and actively adapt the conveyor belt’s speed to achieve the desired output.

If the plastics recyclate has properties specific to its new purpose, the ZS-B side feeder can be integrated into the existing extruder set-up. This unit allows for side feeding of powdered or pelletized fillers, additives, or chopped glass fibers directly into the twin screw extruder’s process section. Should feed-limited ingredients be introduced, Feed Enhancement Technology (FET) can provide a remedy. In this case, the intake section is equipped with a porous, gas-permeable wall to which a vacuum is applied externally. Implementation of FET results in markedly improved intake and throughput performance.

In cases where moisture is introduced into the process due to prewashing of regrinds, it can be extracted again in the extruder’s process section using targeted devolatilization. To this end, the Coperion extruder can be retrofitted with vacuum devolatilization units or the ZS-EG twin screw side devolatilization. Both measures lead to a significant increase in the quality of recycled plastic compounds.

Increases in the proportion of recyclate can also lead to changes in product strand behavior during pelletizing. The strands emerging from the die head are often brittle and tend to break easily. Our SPC and ASC automatic strand conveying systems can help. They automatically guide the extruded strands from the die head to the pelletizer. This is a huge advantage, particularly when starting up a compounder or when strands break. SPC and ASC provide high system efficiency while also ensuring maximum pellet quality.

The technological possibilities for retrofitting a Coperion extruder to process high percentages of recyclate are myriad. We would be happy to advise you and incoporate our plastics recycling expertise into your system. Furthermore, we offer the possibility of testing our technologies and process solutions with your bulk materials  in our comprehensively equipped test labs in order to determine the best solution for your process.