“We have a responsibility to take out impurities," Frédéric Durand continues. "The label is a contaminant. The cap is a contaminant, though this can be sorted away by polymer type. We must also pre-wash the bottles, not only to eliminate the remnants of whatever drink they contained, but also to ensure there is nothing abrasive on them, such as sand or even dust. These have the potential to blunt the blades of the grinder very quickly. Then there’s the grinder itself: we need to be sure the blades are working well, and that there is no damage, because ultimately we want as much consistency as possible in the grain size and distribution.”
How is rPET plastic made?
The process begins with the bottles being sorted, washed and dried and labels removed, ready to be turned into plastic flakes. They are ground, sieved and sorted before they undergo their first quality control check. The more accurately the materials are sorted at a pre-sorting and flake sorting stage, the cleaner the material streams created (for example, sorting into light blue PET). The latest sorting technologies enable this separation and contribute to the quality of the recyclates.
Once this initial step is complete, those flakes can have a number of uses. The preferred option for these flakes is bottle-to-bottle recycling. Other uses include fibers, tray, carpets or other products, but using the bottles’ flakes for a different application is "downcycling": recycling the materials into a product that cannot be easily recycled, so that those materials leave the loop of resource reuse. If the intention is to produce drink bottles and achieve closed-loop recycling, there are two more key phases.
In phase two, rPET plastic production begins. In a process known as “amorphous granulated extrusion”, small plastic cylindrical pellets are made, measuring 2 millimeters by 6 millimeters. This phase is typically only for packaging like trays and bottles, or (in a few cases) fibers.
The final stage involves increasing the viscosity of the material to ensure it is suitable for its intended use. For example, bottles produced for still water will require a different density than those produced for fizzy drinks – the latter needs storage suitable for the higher pressure that comes from the carbonation.
This part of the process, and final decontamination, takes place in a vacuum reactor over a seven-hour period at 200 degrees Celsius.