Extrusion International 4-2021

29 Extrusion International 4/2021 Gneuß Kunststofftechnik GmbH www.gneuss.de BASF SE chemicals.basf.com/global/de/Monomers/ /polyamide_intermediates/mechanical-recycling.html www.basf.com Institut cyclos-HTP www.cyclos-htp.de „ Institute cyclos-HTP GmbH has completed the series of tests commissioned by BASF SE to reassess the recyclability of polyamide 6 (PA6) in coextruded polyethylene (PE) / PA6- multilayer fi lm structures in post-consumer packaging waste. The main result: Multilayer fi lms based on PE/PA6 are certi- fi ed to be recycling compatible for the PE fi lm stream. This was analyzed for PA6 concentrations of up to 30 percent in original packaging fi lms. This result is intended to form the basis for a review of the classi fi cation of PA6 in the “Mini- mum standard for determining the recyclability of packag- ing subject to system participation pursuant to section 21 (3) VerpackG (Verpackungsgesetz – German Packaging Act)” of the Stiftung Zentrale Stelle Verpackungsregister (Central Agency Packaging Register). In the Annex 3 to this standard, PA6 is to date listed as an “incompatible” component, for example, in the waste stream of the packaging group “ fi lm and PE-LD.” In addition to con fi rming the recycling compatibility of PA6 in the waste stream of fl exible polyethylene packaging, cy- Recyclability of Multilayer Films Certi fi ed clos-HTP has also classi fi ed PE/PA6 multilayer fi lms as fully recyclable materials under certain conditions. This is the case while using so-called compatibilizers in PA6-containing fi lm structures additionally to the PA6 content of up to 30 percent in original packaging fi lms. This secures the homogeneous mixing of the polymers which are incompatible in these con- centrations, although this is not absolutely necessary due to the dilution of PA6 in the real waste stream. The certi fi ed compatibility of the examined PE/PA6 systems in the waste stream of fl exible packaging applies to both new injection molding and blown fi lm applications. „ Currently, the recycling of post-consumer PET Bottle Flake is well established and it has become a sought after second- ary meantime. Increasingly, the focus is shifting toward using other sources of PET waste for recycling, such as post-indus- trial fi bre waste and to other post-consumer sources of PET, such as thermoformed pots, tubs and trays. The important difference in recycling these materials is that whereas with PET bottle fl ake, a certain IV drop extrusion is acceptable, the IV of fi bre waste or thermoformed pots, tubs and trays is at a level that any further IV drop would result in unacceptable mechanical properties. Typically, the only an- swer is to install a complicated and/or energy intensive liquid phase or solid state IV boosting processes downstream of the extruder. The Gneuss MRS extruder for PET offers unparalleled decontami- nation performance (and has PET Recycling – Decontamination and IV Control in One Step food contact approval for post-consumer waste without the need for any additional thermal treatment of the material). In addition to this, the newMRSjump version of this extruder provides a drastically increased surface exchange rate under vacuum so that partial polycondensation takes place within the extruder and it is possible to retain the input IV. Additionally, the intense devolatilisation and long residence time of the polymer under vacuum can be controlled to pro- vide a consistent output IV in spite of the inevitable varia- tions in the residual moisture level of the input material. The new Gneuss MRSjump therefore offers both decontami- nation performance to food contact levels and the ability to maintain and control the IV of the PET in one single extru- sion processing step. There is no need to treat the material prior to extrusion and no need for an additional melt or solid phase IV boosting process in addition to extrusion. The result: lower energy consumption, better material qual- ity, greater fl exibility, smaller machine footprint, lower com- plexity, less operator attention and the possibility of using types of raw material which were previously uneconomic to recycle.