PETpla.net Insider 06 / 2020

MATERIALS / RECYCLING PETplanet Insider Vol. 21 No. 06/20 www.petpla.net 39 scrap production that has to be recy- cled or disposed of. Even with high degrees of contamination, the screens of the RSFgenius can be reused up to 400 times, depending on the filter fine- ness, and allow fully automatic produc- tion without the need for personnel for several weeks. Retrofit extruder allows food contact There are many factors involved in the processing of PET in general, and of recycled material in particu- lar. In addition to the mechanical cleaning of the melt by the filtration system, the extruder has the task of thermal cleaning. Here, the process- ing unit should work gently in order to exert as little mechanical stress as possible on the sensitive poly- mer. Through simultaneous vacuum degassing, low-molecular compo- nents such as monomers, oligomers or decomposition products can be removed from the plastic melt on the Building the future in every moment of your business 40 Bar Oil-Free Piston Compressors for PET Applications. hertz-kompressoren.com one hand, while on the other hand moisture escapes here, which would initiate chain degradation and thus viscosity reduction. Finally, more happens in the vacuum zone: con- taminants that can never be ruled out in recycled goods, such as solvents, stabilisers, acetaldehyde scavengers or oils, must escape. The Gneuss Multi-Rotation System (MRS) extruder based on a single screw extruder. This extruder pro- cesses PET melt gently and provides a particularly large melt surface in the multi-screw section with degas- sing zone. In this way, with a simple vacuum of 25 to 30mbar degassing and decontamination performance is ensured. The American FDA authority to grant Gneuss MRS Extrusion Tech- nology a Letter of Non-Objection. As well as in Europe, where the Gneuss recycling process received EFSA approval for the processing of 100% post-consumer PET on thermoforming sheet processing line. Online viscometer completes retrofit solutions It measures a small partial flow of the melt during ongoing production and determines melt temperature and pressure via a precisely manufac- tured slit capillary. Based on internal calculations, the online viscometer constantly provides the representa- tive shear rate and dynamic viscosity. Depending on the values determined, the vacuum in the degassing zone of the MRS extruder is readjusted to keep the melt viscosity within the specified tolerances. Regardless of which key component, MRS extruder, melt filtration system or online viscom- eter, a processor chooses, the ability to process recycled material and still produce high-quality PET sheet is therefore possible. Gneuss states that in combination with the company’s consulting services, an optimum solution can be found for almost any application. www.gneuss.com