“Today’s recycling efforts have an important impact on plastics in the environment,” says Alessandro Dulli, Clariant Masterbatches Global Head of Packaging, “and it is still only a beginning. We can recover – we must recover – much, much greater volumes and turn the vast amount of packaging waste into new raw material. To do that, we need to overcome major challenges around the capabilities of proper sorting of waste to produce a high-quality PCR [post-consumer recyclate], and around issues related to coloration, stabilization, product safety and process stability. At Clariant, we are committed to bringing our knowledge in chemistry, applications and markets to bear on the problem.”
- Antioxidants – The combination of heat and exposure to oxygen can cause plastics to lose mechanical properties or become discolored, and black spots can form. Any of these can render the material unsuitable for re-use. Clariant CESA®-nox antioxidants, added during PCR compounding or the production of new packaging made of recycled material, prevent these problems.
- Processing Aids – The melt behavior of PCR polymers differs from that of virgin material, which leads to a higher risk of build-up around the die, where it can degrade and become discolored. CESA-process additive masterbatches effectively reduce this effect and provide for smoother processing.
To heal or repair damage done to recycled resins, Clariant has developed several additives. Three examples operate on a molecular level:
IMPROVED SORTATION
- Chain Extenders – Condensation polymers like PET polyester are particularly susceptible to damage during recycling. Moisture, solvents and heat can cause polymer chains to break down, resulting in a loss of processability, molecular weight and important material properties. To succeed in high-value product applications, this degraded material needs to be repaired. When added during processing, CESA-extend re-links polymer chains that have broken due to degradation, restoring critical properties and making it easier to use recycled materials.
- Modifiers – Even if polymer chains cannot be completely repaired, these CESA-mod additive masterbatches reduce brittleness and increase impact strength enough to allow bottles and containers made of PCR to better meet top-load and drop-test standards.
- Color Correction – To overcome the color shift that occurs in recycled plastics, Clariant offers different solutions to meet customer needs: a family of PCR colors has been created to allow brand owners develop beautiful colors even when the recycled polymer has an undesirable color tone; other CESA additive masterbatches can compensate the yellowish color shift in transparent and translucent applications.
“This is where we are focusing our greatest attention today.” says Mirco Groeseling, Global New Business Development Manager at Clariant, “We can provide a full portfolio CESA additive masterbatches, as well as RENOL® & REMAFIN® color solutions, to help overcome today’s most critical recycling challenges. People can find out more by contacting us at [email protected]”
- Detecting Dark Colors – Standard black plastic containers, colored with pigments that use carbon black, are currently very difficult to detect by sorting machines in recycling plants as they absorb the near infra-red (NIR) light used for sorting. Clariant’s new CESA-IR masterbatches and alternative pigment systems allow black and dark-colored plastics to reflect NIR light, so they are visible to the sorting sensors.
- Marking Additives – Clariant is working to develop a new sort of taggant to improve the efficiency of the sortation process. The idea is to mark specific applications (e.g. HDPE caps) so that the material can be processed separately, retaining more of its value and potentially allowing it to be re-used in the same application.
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