Extrusion International 4-2021

43 Extrusion International 4/2021 MAS Maschinen- und Anlagenbau Schulz GmbH A-4055 Pucking, Austria www.mas-austria.com Incorporated special features of the DRD dry cleaner include elements that completely dispense with the use of water as a washing medium operating via the principle of an air cyclone. In it, film flakes are dried by friction in a heated air vortex. In the process, adhering contaminants such as sand, dust and soil are separated and discharged by centrifugal forces. The advantage of waterless operation includes lower energy input for the cleaning process, resulting in a significantly smaller CO 2 -footprint. For subsequent extrusion, the MAS twin-screw extrud- er is also well suited to low-bulk-density feed materi- als thanks to its conceptually large feed opening. Due to modular, co-rotating screws and short processing length, plasticizing is designed to be mechanically ef- ficient and simultaneously as gentle as possible. A key goal of the joint development work was to in- crease the surface quality and thus, the printability of the film by minimizing the specks (dust and dirt par- ticles, as well as cross-linked polymer agglomerations) still contained in the recycling film. The functional principle of the MAS extruder are the keys to its success The basis of this system is a co-rotating MAS twin- screw extruder designed to optimize the entire extru- sion process. The short and gentle melting phase in the MAS extruder reduces the formation of polymer cross-links to a minimum. A screw geometry developed directly for processing LDPE films with an increased LLDPE content, together with an adjustable screw speed, enables the shear forces required for ultra-fine homogenization to be applied with pinpoint accuracy. With this, the foreign bodies contained in the melt, as well as already existing cross-linkages, are broken up, crushed and evenly incorporated. This significantly minimizes the effect of specks on the smoothness and optical properties of the film. This results in substan- tially improved printability of the film, a significant im- provement in the print image and a reduction in the amount of ink required (Picture 2). Process technology honored with “Plastics Recycling Award 2020” This process technology, developed by MAS and Car- oda BV, received an award at the “Plastics Recycling Awards Europe 2020”. During this event, which tra- ditionally takes place in Amsterdam, both companies were awarded the main prize in the category “Recy- cling Machinery Innovation” (Picture 3). Summary Through cooperation between plant manufacturer and plant operator, MAS and Caroda BV have devel- oped a process technology that significantly increases the surface quality of recycled films. It consists of the MAS conical twin-screw extruder, efficient melt filtra- tion and optimum melt degassing in the downstream extrusion cascade. In a circular economy, this opens up significantly expanded application possibilities for re- cycling films. Author: Reinhard Bauer – TECHNOKOMM office@technokomm.at Picture 4: From Caroda B.V. with the MAS equipment recycling goods (Picture: Caroda BV) Picture 5: Recycling- Technology-Award (Picture: MAS)