As the use of recycled PET material for the production of filaments and fibre products continues to grow, demand for well-sorted, clean bottle flake material remains high. These flakes are spun directly into POY - Partially Oriented Yarn - filaments, staple fibres, nonwovens and BCF (Bulk Continuous) endless filaments. That technology today is so refined that the products achieve a quality standard that corresponds to virgin material in many applications.
In some cases , however, the quality of the input material hinders the production of recycled materials delivering the required quality or properties. For many textile applications, parameters such as viscosity and homogeneity are crucial, exhibiting virtually no fluctuations. This is not always feasible when using polyester waste that has not undergone rigorous pre-treatment processes.
The VacuFil process developed by BB Engineering resulted from efforts to further develop the potential of post-consumer PET waste and post-production PET material. Headquartered in Remscheid, Germany, BBE is a joint venture between Siegsdorf, Germany-based Brückner Group and Oerlikon Textile, a leading manufacturer of systems for the manmade fibre industry which is also located at the Remscheid site in Germany. BB Engineering combines the recycling expertise of, and functions as the exclusive supplier of extrusion filter technology for manmade fibre industry polymers to both its parent companies. The company has focussed on the development of processes aimed at converting recycled materials, particularly polyester flakes, into market-appropriate products for filaments, fibres and nonwovens.
Due to their modular design, the VacuFil systems are available in various configurations with processing capacities ranging from 300 kg/h and maximum 3,000 kg/h. The systems can handle polyester waste in the form of waste bottle flakes, agglomerated spinning waste or a mixture of both.
Macro- and microscopic melt homogeneity is achieved by means of homogenization drying, controlled plasticizing, gentle filtration and controlled vacuum degassing.
Different target viscosities and starting materials are easily handled by the Visco+ vacuum filter, with no reactor required. The attached vacuum unit, which is automatically regulated between 1 and 30 mbar, removes volatile contamination and ensures a controlled IV increase, resulting in an outstanding melt homogeneity, the company reports. An inline viscosity measuring unit connected to the vacuum system, enables the IV to be continuously and reliably adjusted. Producers are therefore able to generate the specific kind of recycled polyester needed for their application.
“Our decades of competence kicked in while we were developing the VacuFil” said Klaus Schäfer, CEO at BBE.
The entire recycling process is controlled and monitored by Oerlikon Barmag’s GUIDE system, and, with an optional BBE 3DD mixer, producers can not only add additives to the melt, they can also easily change rPET ratios in the main melt from between 5 and 50 percent stream in order to comply with legal standards.
VacuFil premiered at the ITMA 2019 in Barcelona, garnering considerable attention at the trade fair. Since then, numerous tests have been conducted on the pilot system at the Remscheid site using authentic waste material supplied by customers.