By nature, PUR foams have a tendency to stick to the injection molding tool. In order to prevent this, the insides of the molds are usually sprayed with release agents, but these can leave traces on the molded parts. Another option is to apply, a permanent coating to the mold, although this requires disassembly, shipping of the tool to a specialty company, and subsequent reinstallation. An expensive and time-consuming process.
System partners Plasmatreat GmbH, market leader in atmospheric plasma technology, and CeraCon GmbH, engineering specialist in foam sealing systems, presented a newly-developed anti-adherent solution at the K 2010 plastics trade show. They showed how Openair®atmospheric plasma technology makes it possible to process polyurethane without release agents through in-mold application and in-mold regeneration of the coating. In the PlasmaPlus® coating process, an organosilicon compound is mixed with the plasma. Because of the high-energy excitation in the plasma, the compound is fragmented and deposited on a surface as a glassy coating.
The anti-adherent effect occurs solely due to plasma polymerization on the mold surface. Wet chemical release agents are completely replaced by this environmentally-friendly process, and removal of the mold for recoating is no longer necessary, since old coats do not have to be removed. Regeneration can now occur, for the first time, directly in the injection molding tool.