ADDITIVES | MATERIALS
The additive route to improved recycled plastics
The use of additives can both improve the plastics recycling process and the final quality of recyclates. Mark Holmes reports on additive and masterbatch suppliers active in the field
An increasing number of additives are being specifically developed for the plastics recycling market. These range from additives and master- batches that can now be used to improve near infrared (NIR) sorting, in particular of black packag- ing materials, through to aids for other areas of the recycling process such as washing and separation. Additives are now also being introduced to upcycle plastics and improve their odour and properties to be re-used in a wider range of increasingly more demanding applications. Demand is high for additives for the plastics
recycling market, reports Evonik. “The recycling plastics market itself is very dynamic,” says Ido Offenbach, Americas Segment Manager, Polymer Specialties. “We are observing high capacity of new recyclers all over the world, especially in Europe. As a result, the quantity of the recycled plastic is consistently increasing. Therefore, it is not surprising there is a need for additives to optimise the recycling process and to increase its speed. To achieve these targets, we have developed addi- tives for the washing and floatation steps, as well as for the upcycling compounding steps.” However, there are specific problems that
require new solutions. “The mechanical recycling process is far from perfect,” says Offenbach. “Therefore, optimisation is needed. Currently, most developments are typically focused on improving efficiency and the cleaning process – the washing step – of mechanical recycling, as well as improving the sorting process to achieve more homogenised recycling resins without contamination, removing
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malodour, and adjusting MFI/MFR of the recycled polymers. Currently, we are primarily developing solutions to improve the efficiency of the washing step and solutions for the odour absorber.” Evonik says its main area of focus is to optimise the mechanical recycling process, particularly in the wet stage and during the process, and in the upcycling plastics steps. “For the wet stage, we offer high efficiency additives that achieve better defoaming, wetting, de-inking, and delabelling performance than the market standard. These additives have global food contact status.” Tego Antifoam 4-94 is an example of an Evonik additive that is suitable for post-consumer (PCR) and post-industrial processes. The company has also developed a dewatering aid, Tego XP11022. This additive is used before the drying process, reducing the water content of plastics, which results in a shorter drying process. It also lowers the energy consumption of this process. The company says: “In addition, our odour absorber series, Tego Sorb, reduces malodour during the recycling process and in upcycled plastics. This series includes 100% active odour
Main image: Gabriel-Chemie has achieved COTREP certification for NIR-sortable black master- batch
March/April 2021 | PLASTICS RECYCLING WORLD 39
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