Extrusion International 5-2020

33 Extrusion International 5/2020 Gneuss Kunststofftechnik GmbH Moenichhusen 42, 32549 Bad Oeynhausen, Germany www.gneuss.com ponents for PET processing. The MRS Extruder with its high degassinganddecontaminationperformance, powerful and automatically operating Rotary Filtration Systems, an On- line Viscometer as well as the Polycondensation Unit Jump, which can ensure a targeted viscosity build-up of the PET melt of up to 0.3 dl/g, are available. Each of these machine components is available individually or in combination and can be retrofitted into an existing production line to adapt it to the changed requirements. In this way an ideal result can be achieved with comparatively low investment costs. Main component MRS Extruder The extruder has a special task when processing PET fiber residues, since the plastic must not only be melted and ho- mogenized, but if possible, also dehumidified and freed of volatile components if possible. While post-consumer waste can contain mainly moisture and a wide variety of solid dirt particles, production waste from fiber manufacture usually contains spinning oils, which are important for processing but make recycling more difficult. Regardless of which form of thermal cleaning of the waste material is required, the Multi Rotation SystemExtruder fromGneuss Kunststofftech- nik takes over this task. This is due to its special processing-technical design based on a single-screw extruder. Thanks to the enormously large melt surface created in themulti-screw section of the extrud- er, a high degassing and decontamination performance can be achieved and spinningoils canbe effectively removed. No thermal pre-treatment of the residues is necessary. Among others, this was a good reason for the Belarusian processor Mogilevkhimvolokno located in Mogilev, one of the larg- est Eastern European producers of staple fibers, to retrofit an MRS 90 to its existing line. With a capacity of around 350 kg/h, all agglomerated fiber residues arising in production are processed, decontaminated and then re-polymerised to PET with a defined IV value in a polycondensation reac- tor without any further preparation. The situation is similar at the Chinese fiber producer Suzhou Shenghong Fiber Co. Ltd which operates an MRS 130 with a capacity of up to 800 kg/h. Here, too, the fiber waste is first shredded, melted in the MRS and thermally cleaned before it is brought back to the desired IV value in the polycondensation reactor and then processed into POY and FDY yarns. For the first time, stretched fibers with a high recycled content can be pro- duced in this way. MRS extruders are in use worldwide for processing PET waste materials. This is also the case with the South Ameri- can company Valerio, which operates an MRS 90 with a ca- pacity of 450 kg/h to produce staple fibers from very dirty bottle flakes. Mechanical cleaning indispensable Especially when using heavily contaminated bottle flakes, as is the case with the South American Gneuss customer, me- chanical melt cleaning is indispensable. Valerio decided in favour of an RSFgenius 90 which, like all melt filtration sys- tems from Gneuss Kunststofftechnik, operates with a rotat- ing filter disc. Especially in recycling applications, low material losses and infrequent filter element changes are important in order to ensure a high efficiency of the overall process. Therefore, the RSFgenius not only operates pressure- and process-con- stantly, but also carries out the cleaningof thefilter elements fully automatically by means of an integrated back-flushing system. For this purpose, a small amount of filtered melt is regularly shot through the dirty screen by a high-pressure impulse over a narrow gap. The quantity required for this is freely adjustable and in practice corresponds to about 0.01 to 1 % (with very high contamination) of the throughput. This means that the filter elements can be reused up to 400 times, depending on the filter fineness, which means fully automatic filtration without the need for personnel for sev- eral weeks in some applications. Even the twomajor fiber producers in Belarus and China are convinced by the machine component “filtration system”, which is also available as a separate unit and can be inte- grated into any existing line. They use an RSFgenius 90 resp. anRSFgenius 175 according to their throughput capacity and thus ensure a clean melt. This is especially essential for fiber production, as foreign particles could clog the spinneret and cause fiber breakage, which in turn would greatly reduce production efficiency. Further key components available With its enormous know-how in PET processing, Gneuss not only advises its customers –which is very important especially for retrofit solutions – the machine manufacturer is always working on the further development of its machine compo- nents. In addition to the online viscometer, which records and controls the melt viscosity during production and, via a control system, readjusts the entire process in case of fluc- tuating viscosity, the polycondensation reactor Jump is one of the latest new developments. It is flanged directly to the extrusion unit and, with its sophisticated processing-techni- cal concept, ensures a targeted viscosity build-up of the PET melt. The Jump thus represents a compact, economical and fast alternative to conventional SSP systems and enables the direct return of the residual materials into the production process. It can also be retrofitted to an existing line at any time. Polyreactor JUMP for flexible IV increase and adjustment