Achieving food-contact grade recyclate through mechanical recycling has long been a challenge that recyclers of, among others, polystyrene have been hard-pressed to meet.
In collaboration with the Fraunhofer Institute for Process Engineering and Packaging IVV in Germany, Styrenics Circular Solutions (SCS), the value chain initiative established to increase the circularity of styrenic polymers, has now successfully demonstrated that it is possible to mechanically recyclable polystyrene to food contact standards.
SCS conducted a number of challenge tests to assess whether a mechanical recycling process in combination with the supercleaning technology developed by machinery manufacturer Gneuss could consistently achieve the very high purity levels needed for food contact materials.
In the tests, post-consumer polystyrene waste from food contact packaging to which impurities had been added in order to simulate the worst-case scenario, was used. The results showed that the cleaning technology yielded outstanding r-PS purity levels, a finding that is supported by the intrinsic properties of polystyrene. Polystyrene is a low diffusion polymer, which prevents waste contaminants from entering or migrating through the polymer matrix.
“The test results are of crucial importance as they give brand owners and packaging producers full confidence that the applied mechanical recycling technology delivers the required high purity levels for their business. Most importantly, the qualities of the polystyrene molecule remain stable and do not degrade in multiple mechanical recycling,” said Frank Eisentraeger, product director PS EMEA, INEOS Styrolution and member of the SCS working group Waste Feedstock.
The quality of the r-PS will allow it to be used by producers of packaging for the food industry in their existing industrial production processes. Various SCS members have delivered a proof of concept that mechanically recycled polystyrene can serve as a drop-in solution in form, fill and seal (FFS) production lines. Multiple variants for packaging are possible: single layer, co-extrusion of the r-PS with virgin polystyrene or use of the recyclate as middle layer between virgin polystyrene (A-B-A).
It is a huge milestone in styrenics' contribution to the circular economy, noted Jens Kathmann, Secretary General SCS.
“We are delighted to take the next step by filing our application with EFSA for food contact acceptance,” he said.