In the compounding extrusion of recycled resins, screen changers play a key role in removing contamination, such as paper, wood, aluminum foil, rubber or other unwanted plastics, from what will end up as the pellets. Some compounders of recycled resins are investing in more effective filtration technology in an effort to add value to their products so they can better compete with low-priced virgin resin, says Mike Diletti, president of Ettlinger North America LP, Tyrone, Georgia. The challenges of processing highly contaminated reclaimed plastics also are influencing the market for melt filters and screen changers.
Some in the industry use the terms screen changer and melt filter interchangeably. Both have disposable or reusable screen packs. But screen changers involve a manual process of changing the screens, often after just a few minutes. Melt filters offer a more continuous, automated process that is gaining popularity in some circles. But melt filters represent a much bigger upfront cost.
“It’s constant filtration, and the screen will speed up or slow down automatically based on the level of contaminant that’s in the material,” says Mike DeMatto, president and chief operating officer at plastics compounder CTC Plastics LLC, based in Dayton, Ohio.