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Black plastic packaging- a symbol of luxury goods, premium quality electronics, delicious food products, and disregard for the environment. Well, a lot of people think that you can't recycle black plastics, and it's easy to see where this idea comes from. But is that actually true? Let's look at the facts. Post-consumer black pigmented plastics have an end-of-life value if they can be properly sorted and put back into the recycling stream. The challenge has been around detection. Most black plastics cannot be detected, so they end up going to landfills. One way to prevent this from happening is to use a black colorant that is detectable within a material recovery facilities detection system, which allows for the plastic to be sorted, collected, and sent to processors to be converted into new plastic products such as packaging. Let's unpack this together to understand how it's possible.

Sortation Process for Black Plastics

When we considered environmental impact of black plastics, it's important to consider the sortation process that's used in material recovery facilities or MRFs. MRFs use NIR technology to identify the type of plastics, for example polypropylene, polyethylene, or PET to be able to sort them into the right stream. NIR or near infrared sorters depend on light reflectors to identify the material and because carbon black strongly absorbs the light instead of reflected it back to the detector, the carbon black trays cannot be detected and therefore not sorted and end up going to the landfill.

Recent advancements in artificial intelligence technology incorporate robotic picking to sort the different plastic materials. This approach tends to be slower and requires significant capital investment compared to the NIR sorting process, so we can see that advancements in sorting technology can allow for carbon black containers to be recycled. The other approach is through material design, which plays well into Sonoco's strengths.

Developing NIR Black Coloring at Sonoco

In the development of the NIR black coloring our technical experts at Sonoco worked with our supply partners to screen through a list of viable options, which we were able to reduce down to the best candidates to select for our testing in our own product formula. Leveraging our chemistry and material science knowledge, our engineers conducted extensive trials to select the right color that closely match the properties of carbon black that's been used for years. We also perform analysis to ensure that the new color meant all the food safety and performance requirements.

Testing the New Formula's Processability

Then after we found the right colorant the team went a step further carrying out extensive testing to demonstrate the processability, the mechanical performance, and the quality to meet our customers application requirements. This included pilot trials to produce sample trays that underwent a broad range of tests to determine the heat stability, the organaleptic quality, and the impact resistance of the package. Which for some applications required us testing from frozen to high temperature conditions. We certainly put the new formulated tray through the ringer to prove that its performance was in fact comparable to the tray with standard carbon black in real world use conditions. And that it was up to our customer standards and performance, and it met every regulation and compliance requirement in the industry.

In addition to proving that this new NIR detectable black would perform for our customers as expected, we also had to prove that it was in fact recyclable. Following some of the recycling industries leading testing standards. We produced trace samples formulated with the new NIR colorant and ran sorting trials to prove that NIR black trays can be detected and sorted into the correct plastic stream using traditional optical sortation equipment. We tested the collection stream with the new NIR colorant against a baseline of known materials in order to prove the effective variants of the new material. If it's less than 5% difference, then yes, it can be sorted effectively.


Once we've cleared this hurdle and our pilot plant trials were moving forward with key customers to get their feedback on the performance test, it was time to apply for a pre-qualification letter from how to recycle which allowed us to help our customers have recycled packaging options to choose from in order to help them reach their sustainability commitments.

Ultimately the conversation around the recyclability of black plastics is bigger than whether or not the substrate is NIR detectable. These are important advances in materials science, but there are other factors that we're considering here Sonoco as well. Chemical or advanced recycling is a relatively new technology in the industry that can break plastic down and to its building blocks that can be converted, and to other valuable secondary raw materials including back into making new polymer. The advantage here is that it doesn't have the same issue with colorant contaminations and the waste stream as mechanical recycling. Likewise, there are large portions of the industry that are simply moving away from carbon black substrates all together and choosing natural or clear over pigmented trays. NIR detectable black is an important intermediate step in this progression for many of our customers.

It's easy to see why so many people believe black plastics can't be recycled. But the truth is, it's the innovations taking place in the MRFs to improve material detection and sorting, or the development of new materials for packaging, or leveraging chemical recycling technology. There are plenty of options to keep these trays out of landfill while preserving the performance and presentation we all expect in our consumer packaging choices. And that's this episode of sustainability unpacked.

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