Founded over 30 years ago to provide central research and development for fiber manufacturers, the KTDI is located in the center of Korea’s fiber manufacturing region. It has a large technical center which is open to the public and for general use, which is especially attractive to small and medium enterprises (SMEs) as they can run trials on the equipment at the KTDI technical center.
With the increasing emphasis on sustainability, fiber manufacturers are looking for ways of using recycled material for making fibers, whether it be recycling post-consumer PET bottle flake to high quality yarn, or recycling PET fiber waste from fiber production. For use in its technical center, the Korea Textile Development Institute (KTDI), Daegu/Korea, decided to buy a Gneuss MRS 70 Extruder, with dosing feeders, vacuum system, automatic Melt Filtration System and Online Viscometer for processing PET waste to pellets, with fiber spinning in mind. With the MRS extruder, it is possible to process PET waste directly to fibers but for a pilot line, the intermediate stage of processing to pellets/chip gives more flexibility.
When processing post-consumer PET bottle flake to pellets (chip) for yarn manufacture, the MRS extruder from Gneuss Kunststofftechnik GmbH, Bad Oeynhausen/Germany, offers the opportunity to adjust the viscosity of the PET by means of the vacuum. The MRS extruder can be fed with undried PET bottle flake and the moisture is extracted under vacuum in the multi rotation section of the extruder. The depth of the vacuum determines how much moisture is removed and how much effect hydrolysis has on the viscosity of the PET melt as it comes from the extruder.
Using the reading from the Online Viscometer, the KTDI can adjust the vacuum level to give the required IV which can vary considerably depending on the application of the fibers (textile or technical grades). The automatic viscosity control can even automatically vary the vacuum depth in order to maintain the set viscosity. A consistent viscosity is important when high quality fibers are manufactured. The Gneuss Online Viscometer VIS provides accurate, reliable and repeatable real time measurement of the dynamic viscosity.
Another feature is the ability to process PET post-industrial fiber waste, which has both a high residual moisture level and is coated with spin finish oils. This fiber waste is notoriously difficult to recycle. The successful application of the MRS extruder in the processing of agglomerated wet, spin finish oil treated PET industrial fiber waste has shown how both the moisture and the spin finish oils could be efficiently and reliably extracted under vacuum in the multi rotation devolatilizing section of the extruder.
The devolatilization performance of the MRS extruder also equates to good decontamination performance. Post-consumer PET bottle flake can be recycled for food contact applications to FDA/EFSA standards. Consequently, the pellets/chips made on the extruder can be used for food contact applications.
To round off the package, the KTDI also specified the Gneuss RSFgenius Melt Filtration System. This system is self-cleaning and offers the possibility of very fine filtration even with the relatively high contamination loads which are encountered when processing post-consumer PET bottle flake. The emphasis at the institute is on manufacturing pellets/chips for high quality fibers, which require fine filtration. The RSFgenius Melt Filtration System offers this possibility without causing disturbances in the process and with long intervals between filter element changes.