Within the packaging industry, the use of PET sheet is on the increase and the use of recycled material is likewise on the increase. Whether the PET sheet is used for transparent packaging for food (trays or tubs for fruit, vegetables, meat, cookies etc.) or for non-food (such as blister packaging) it is always important to take account of the particular properties of PET and it is exactly this which Gneuss has done.
With the Multi Rotation System (MRS) Extruder, Gneuss has developed the only extruder specifically designed not only with the material PET in mind, but with the reprocessing of PET. With the MRS extruder Gneuss offers a processing unit which enables PET to be extruded cost effectively, without any pre-drying or crystallisation. This applies both to the processing of both virgin and post-consumer bottle flake with a residual moisture level of 1% and in some cases more. The extruder will also easily handle PET / PE scrap (laminated sheet) and mixtures of PET and PETG. Thanks to the extremely high polymer surface exchange rate under vacuum in the MRS section, a vacuum level of only 25 bar is required in order to achieve 100% moisture extraction. Another effect of the extremely high polymer surface area exchange rate under vacuum is the excellent extraction of volatile contaminants. The system achieves the requirements of both the FDA and EFSA without restrictions PET sheet made on the MRS extruder is therefore suitable for food contact applications whatever input material is used and without any pre-treatment of the input material.
The Gneuss Processing Unit includes also the unique Gneuss Rotary Melt Filtration System for the efficient removal of solid contaminants with fine filter elements even on post-consumer bottle flake. The Gneuss Online Viscometer ensures a consistent, defined IV value of the polymer thanks to the intelligent control system and is an extremely useful tool for quality monitoring and control.
Gneuss offers complete lines including the up- and downstream components from the material dosing system to the die, roller stack and to the winder, which are all tailored to the exact requirements of the individual customer. As Dr. Carl-Jürgen Wefelmeier (Manager Business Unit Film and Sheet) was pleased to inform us: "We are very proud that we can offer turnkey PET sheet extrusion lines - from the project engineering to After-Sales-Service".
Gneuss can offer individual systems, whether it be for the replacement of existing, conventional extruders in existing lines with Gneuss Processing Units or the design, supply and commissioning of a complete new PET sheet line. In each case, sheet with a high transparency and gloss, extremely low haze and low yellowness with good thermoformability can be made with great efficiency.
The complete sheet extrusion lines are highly flexible with regard to the input material and with regard to the sheet which can be made on them, inlcuding even sheet for optical applications.