When Gneuss supplied a new PET recycling line to the Korea Textile Development Institute - known as KTDI - the company could not have imagined that it would ultimately end up being shown on Korean television. Nonetheless, once the line - designed to recycle PET to fibre grade quality - was installed, it attracted such interest that that is exactly what happened.
Founded over 30 years ago in the heart of Korea´s fibre manufacturing region near Daegu, KTDI serves as central research and development hub for fibre manufacturers. Although originally mainly government funded, the institute today generates the bulk of its income from the contract research, testing and training services it provides to the fibre industry, as well as the support received from the Korean Ministry of Trade, Industry and Energy and from the City of Daegu.
As sustainability looms ever larger in the PET industry, fibre manufacturers everywhere, including Korea, are seeking ways to use recycled PET to produce their products. Different options are all being explored, from the use of post-consumer PET bottle flake to PET fibre waste from fibre production.
In Korea, these efforts are supported by KTDI. The institute therefore decided to purchase a Gneuss MRS 70 Extruder, with dosing feeders, vacuum system, automatic Melt Filtration System and Online Viscometer, with fiber spinning in mind. With this equipment in place, the institute is able to test the processing of difference types of PET waste into pellets. While the MRS extruder can process PET waste directly to fibres, this pilot line will first explore the intermediate stage of processing to pellets/chip gives more flexibility.
KTDI opted for the Gneuss system because of advantages such as the opportunity to adjust the viscosity of the PET when processing bottle flakes to pellets - when fed undried PET bottle flakes, 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, KTDI can adjust the vacuum level to the level required, depending of whether, for example, technical or textile fibres are required (the intrinsic viscosity is not the same for the two applications). A consistent viscosity is important when high quality fibres are manufactured.
The Gneuss MRS extruder also has the capability to process post-industrial PET fibre waste. This is notoriously difficult to recycle due to its high residual moisture level and because of the coating with spin finish oils. It had already been demonstrated back in 2011 that the extruder could efficiently and reliably extract both the moisture and the spin finish oils under vacuum in the multi rotation devolatilising section, which made the decision easier for KTDI. The fact that the devolatilisation performance of the MRS extruder leads to a good decontamination performance was another plus: the system can recycle post-consumer PET bottle flake for food contact applications to FDA / EFSA standards.
The self-cleaning melt filtration system provides a very fine level of filtration, even with the relatively high contamination loads that occur processing post-consumer PET bottle flake.
The new line is installed at the KTDI’s technical centre, where it was featured on television. The centre is open to the public and intended for general use. For small and medium enterprises, the facilities offer the opportunity to run trials on the equipment centre without having to invest in the equipment themselves.