Recycling and Upcycling through Maris Extruders
Established near Turin in 1962 to manufacture extruders and dies for pipes and profiles, Maris quickly became a leading player in the early development of nascent technologies. Focused on the production of co-rotating twin-screw extruders for various application, they have recently patented a continuous process for rubber devulcanisation. In this case, the vulcanised rubbers are recycled using a continuous system, allowing them to be reused (in proportions ranging from 15% to 50%) in new formulations for the same original application. What is more, the percentage
of devulcanised material in the compound can be further increased to obtain different formulations. In this regard, the devulcanisation process can also be applied to post-consumer materials, since it involves careful material selection, identification and treatment steps. We are referring to the large volumes of end- of-life tyres (ELTs) that can certainly consider a very useful “secondary raw material”. Still in application terms, recycling – or better – upcycling, is a constantly evolving and growing sector.
Maris’s response to the need to recycle plastic materials (polyolefins, PVC, PET and also expanded materials) with high contamination and high moisture content is Evorec Plastic Plus. This combination of two technologies – a single screw extruder and a corotating twin screw extruder – makes it possible to recycle very critical materials with a single extrusion system. Just to summarize the features of this tandem solution, it has been now reached a point at which it is possible to fully exploit the potential of both the single screw extruder and the corotating twin-screw extruder, in a single machine and in a single step.
In other words, by combining two specific, complementary expressions of our know-how, it is possible to feed non-free-flowing materials, carry out double filtration, obtain highly homogeneous
materials, and introduce additives/fillers into the recycled polymer. It is also possible to process materials with a high moisture content and a very high level of contamination; this would not be possible with a twin screw extruder alone, but thanks to this combination, it is now feasible.
Regarding the upcycling example described in this article, figure 1 comes to our aid, showing the five phases of the single screw extruder: 1) grinding, dehumidification, storage; 2) feeding; 3) melting; 4) first degassing; 5) first filtration. After these operations, the post-industrial or post-consumer waste is ready to be fed continuously towards the corotating twin screw extruder. Figure 1 also lists the phases of this second step: 6) homogenization; 7) second degassing; 8) side feeding of polymers, fillers or additives; 9) third degassing; 10) second filtration and granulation/palletizing.
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