PETpla.net Insider 11 / 2020

MATERIALS / RECYCLING PETplanet Insider Vol. 21 No. 11/20 www.petpla.net 15 Since melting and decontamination happen in separate steps in the SSP process, the final IV result cannot be influenced during decontamination if the quality of the input material is not consistent. In fact, the detailed result is only known after the entire process has been completed. In contrast, P:React carries out the entire decontamination in the liquid phase, so that the control parameters described above can directly control the IV increase. If, for example, the input IV value drops, the vacuum level is automatically increased without operator interven- tion, keeping the output IV value very stable. This is particularly important because the IV value is first reduced in the extrusion process. The course of IV loss in the extruder, subsequent increase in the reactor and output stabilisation is shown below: Fig. 3 IV value development The stabilisation of IV value, which is not possible using solid state methods, allows other solutions for integrated processes. P:React has been used as upstream equipment for some time now and is directly coupled to the production of semi- finished products such as films, fibres and preforms. This results in further advantages and efficiencies on the manufacturer side. Energy- intensive heating and re-melting of rPET pellets is no longer necessary. More importantly, the recycling pro- cess does not need to overshoot IV buildup to account for subsequent IV loss in the re-melt step. As a result, the PET material is less stressed and the entire process is simplified in terms of costs and production time. A further advantage of the LSP process is its ease of use and high process stability. On the one hand, a standardised extruder without vacuum, but optionally with degas- sing stages, is used, and on the other hand, production interruptions do not affect the quality of the starting mate- rial. Since the vacuum is reduced when the material remains in the reactor for a longer period of time, the IV value remains constant at the desired level even during longer downtimes. In order to help operating personnel and to achieve a constant IV value, NGR has integrated an online viscometer. The measure- ment results are constantly reported to the plant control system. If minor deviations occur, the required control parameters are immediately adjusted to stabilise the output IV. Specifica- tions of the input material thus take a back seat and manual intervention by operators is no longer necessary. A constant granulate quality with consistent IV value and the feeding of a constant melt specification into subsequent processes is guaran- teed. It is possible to supplement the input material with additives or colour masterbatches, in order to optimise the output material. Corresponding feeding and dosing devices can be provided as an option at any time. NGR operates a special PET pilot plant, with a fully instrumented test laboratory on site, where clients work alongside with NGR’s own experts to design their ideal process. Custom- ers’ own material is processed in the required quantity and then subjected to a detailed properties analysis. In summary, NGR’s LSP pro- cess represents a major step in the ongoing struggle for sustainability. PET waste from both post-consumer and post-industrial resources can be reprocessed quickly and cost effectively. LSP can also be used to reprocess PET/PET-G or PET/PE composites, which have, previously, presented problematic challenges. In today’s commercial environ- ment, where many countries are establishing deposit and collection systems, PET reprocessing is already of special importance but it must also overcome economic hurdles and per- form at high commercial levels. For this reason, numerous recycling com- panies and globally active producers of semi-finished products already rely on the NGR P:React series. All these companies can take advantage of the benefits for themselves and, simulta- neously, reduce their CO 2 footprint. www.ngr-world.com Fig. 4 P:React