Extrusion International 1-2023

23 Extrusion International 1/2023 ficult to recycle XLPE or PE-X in such a way as to obtain the virgin-like PE required for these high-perfor- mance applications. By drawing on its polymers exper- tise and recycling know-how, Borealis can now offer its customers a circular solution for crosslinked PE. In a series of tests conducted by Borealis, XLPE and PE-X plastic waste were pre-treat- ed and fed into the Borcycle C chemi- cal recycling process. This chemically- recycled material was analysed and determined to be suitable for use as cracker feedstock in the production of new ethylene in the manufacture of virgin-grade XLPE and PE-X. The proprietary and evolving re- cycling technology Borcycle C trans- forms plastic waste streams into val- ue-added products. These chemical recycling solutions complement me- chanical recycling by turning difficult- to-recycle plastics – like crosslinked polyethylene – into virgin-level grade materials with the highest safety and performance characteristics. Grades in the Borcycle C portfolio of circular polyolefins are ISCC PLUS certi - fied according to the third-party mass balance methodology. This allows the customer to track and quantify the ef- fective circular feedstock used at each step in the manufacturing process. Borealis AG www.borealisgroup.com Borealis Borcycle™ C chemical recycling process breathes new life into crosslinked polyethylene (PE) types such as XLPE and PE-X (Photo: © Borealis) Melt Filter for Blown Film Applications  Producing quality blown film is not an easy task. A film bubble reacts sensitively to changing process conditions, and only minor changes in temperature, viscosity, and especially pressure can have a negative impact. Existing filters provide the necessary process stability and deliver clean, homogenous melt for a high-quality blown film – when only virgin material is used. But this won't be the case much longer. The social call for more sustainability in the plastics industry has led to new laws and regulations. Producers face tax penalties and other consequences if they don't increase their use of re- cycled material significantly. But adding recycled materials to the mix is an additional disruptor to an already delicate process. Depending on their size, contaminants can cause optical flaws and bubble ruptures, leading to line shutdowns. "The change from using only virgin mate- rials to including recycled material is huge and needs new, innovative technology to support that transition. But we like a chal - lenge," says Christian Schroeder, Global Segment Manager for the recycling market at Nordson. " We developed a melt filter, based on our unique backflush technol - ogy, that enables the use of recycled ma- terial while keeping the process stable and the end product quality at the usual high level.“ "Melt filters without a backflushing function have limits when processing recycled material. Contamination levels are high, and the screens clog fast," explains Stefan Woestmann, Process Specialist. "Screens are expensive, and the changing procedure is time- consuming. Through backflushing, the screens are cleaned from contam- ination and debris over and over, so producers need fewer filter elements and operators need to perform fewer screen changes." To cope with the high process pressures in blown film ap - plications, Nordson made patent-pending changes to its al- ready proven backflush technology. "It was important to us to remain pressure constant even under difficult conditions to ensure high film quality," reports Stefan Woestmann. Pressure consistency is an essential component of operat- ing a blown film line successfully. And in this high-pressure application, it is even more important to avoid pressure fluc - tuations through intelligent solutions. Each screen change is a sensitive step in the filtration process, as the empty cavity must be filled with melt again after the change. If this hap - pens too fast, pressure fluctuations are likely. "This is a significant issue in blown film lines since the film is usually very thin and reacts sen - sitively to such events," explains Woestmann. "The BKG ® HiCon™ K-SWE-HD/RS melt filter is equipped with the patented melt pressure con- trolled venting start that fully automizes the fill - ing of the screen cavity after a screen change for maximum pressure consistency. Additionally, the filling is done so carefully that no air entrap - ments endanger the process or the end product. Producers can rely on a stable process and great qual- ity of the blown film," explains Woestmann. The processing of recycled material generates more waste than that of virgin polymers because melt is re- moved from the filter during backflushing and vent - ing. The BKG ® HiCon™ K-SWE-HD/RS melt filter is designed so that this happens in a clean and maintenance-friendly way. The safety cover can be opened vertically, allowing the operator to reach the filter piston from all sides, which facili - tates cleaning. Nordson BKG GmbH www.nordson.com