Recycling: New Vacuum/Nitrogen SSP Technology Enhances RPET Purity

Austria-based Erema, U.S. office Ipswich, Mass., launched its newly developed Vacunite technology at the PETnology conference in Paris. This technology brings together Erema’s Vacurema bottle-to-bottle process with newly patented, vacuum-supported solid-state polycondensation (SSP) from Polymetrix, Oberbüren, Switzerland. 

One unique aspect of this combination is that the thermal process steps take place in nitrogen atmosphere, with the result is rPET pellets that are unique in quality and meet food-contact requirements, according to Erema.

The company believes that the Vacunite technology is the answer to the challenges PET recycling will face in the future. Christoph Wöss, Erema business development manager for the bottle sector, stated: "The growing commitment in society to handling plastics in a responsible way means that both political requirements and voluntary pledges of major beverage brands call for a significant increase in the amount of recyclate in end products. To fulfill these requirements, even more material in general and with varying quality due to different collection systems has to be recycled while, at the same time, the big brands are becoming even stricter with their requirements regarding the recyclates produced.”

The process is based on the combination of the Vacurema technology that has been enhanced for this application and the newly patented, vacuum-supported nitrogen SSP from Polymetrix. All thermal process stages take place in nitrogen atmosphere, largely eliminating flake and pellet discoloration and removing additives that could lead to undesired reactions in the melt. Another reported benefit of Vacunite is the vacuum support cleans the nitrogen, which means it can be returned to the previous processing stage and nitrogen consumption is reduced as a result. Any remaining dust particles are removed from the pellets before filling to avoid preform contamination. "Using vacuum support and nitrogen atmosphere creates rPET recyclates that far exceed all existing food contact requirements, even those of the major beverage brands," Wöss stated.

The recycling technology reportedly also stands out through its comparatively compact build, low energy consumption and, compared to vacuum SSP systems, considerably lower maintenance. The height and substructure also have less impact on the dimensions of the plant building compared to other SSPs, the company stated. Depending on machine type, 50 to 60 square meters of floor space is sufficient for the SSP part. The energy consumption of Vacunite for the entire production process from the flake to the final pellets amounts to 0.35 kWh per kg.