The cooperation between the recycling machine specialist NGR and the extrusion expert KUHNE GmbH is entering its next phase. Since first revealed at K 2016, several joint projects have been implemented, and interest i n the combination of recycling and direct sheet production has intensified since then. Therefore, at K 2019, a demonstration line for viewing direct RPET to Sheet has been arranged in the large R&D area of the KUHNE Group in the nearby St. Augustin.
In-depth tests on pilot plants paired with experience from production plants have shown that a wide variety of PET waste can be processed on such plants: from typical industrial waste such as thermoform skeletons or even fibers - including PETG - to typical post consumer waste such as PET bottle flakes or other PET waste such as flakes from multilayer films (up to 10% foreign polymers). This diversity provides the flexibility required to ensure ample raw material supply on the one hand, and to gain the most value of the raw material on the other.
After melting in the extruder and filtration, the PET melt enters the LSP reactor (LSP = Liquid State Polycondensation) - the technological heart of the line. Here, harmful chemicals are removed far below EFSA and FDA limits and at the same time the IV value (intrinsic viscosity) is boosted to the desired level. The IV which reflects the PET molecular chain length, is automatically controlled within a very narrow tolerance range by the line and thus ensures very uniform, high-strength flat films.
Thermoformers can thus produce thermoformed packaging with very uniform and high strengths, excellent optical properties and approved for 100% food contact. Due to the excellent physical properties, automatic filling and sealing lines can be operated safely and efficiently. From the consumer’s perspective, the rPET cups have a sturdy feel, high gloss and transparency such that the product is highly preferred against lesser quality reprocessed materials.
"With NGR's recycling solutions, we are trying to strengthen the circular economy and find ways to improve product properties even further compared to conventional processes. The cooperation with KUHNE Group supports us in this very much," says Thomas Pichler, Technical Director and coowner of NGR.
Rainer Bobowk, Business Unit Manager Smart Sheets at KUHNE Group, adds: "The PET melt coming from the recycling extruder and through the LSP is seamlessly transferred into the KUHNE sheet line. The T-channel die with internal deckling, specially developed by KUHNE for the production of PET films, distributes the melt into the Smart Sheets calender. Additional functional layers can be added via co-extrusion and a KUHNE multi-layer feed block. Later features such as thickness measurement, a silicone applicator and the final film rewinder complete the system. The rPET films produced in this way are characterized by extremely tight dimensional tolerances and uniform strength with excellent optical properties. The extremely stable operation of the system due to the high and uniform melt quality - otherwise only possible with virgin material - guarantees our customers an extremely high productivity".
NGR and Kuhne encourage all who are interested in visiting the PET recycling/sheet production line to register with your NGR or Kuhne Group contact before or during the K 2019.