Polymer Processing Aids: With or without fluorinated molecules?

Let's face it, the topic of PFAS is one of the hot topics for plastic food contact packaging.

Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) are a large, complex group of manufactured chemicals that are ingredients in various everyday products and their molecules contain fluorine atoms. Among other things, they have been used to prevent food from sticking to paper packaging: these PFAS were intentionally added to create functionality in the packaging. According to the NIEHS, scientific studies show a widespread occurrence, numerous exposures, persistence in the environment, a very large number of different molecules, a possible bioaccumulation in living beings. Many PFAS have been banned over the years, but many still remain.

In the absence of a national consensus for the moment, the States have taken the lead. This is why several bills in the United States have banned PFAS from paper or plant-based food packaging: these bans are already in effect in California and New York, and soon in Washington State. More are coming in 2024 (in Colorado, Maryland, Hawaii). During 2023, other states will also implement bans, but they will apply to all food packaging, regardless of the materials used to make it. The Flexible Packaging Association published a first fact sheet in July 2022.

If we exclude materials based on plants or paper, are flexible plastic food packaging covered? 

Polymer processing aids (PPA) containing fluorinated molecules are used in the extrusion process of plastic films. PPAs act at the interface between the plastic and the metal where they mainly remain, thus avoiding resin build-up on the production equipment. The use and the molecules are very different from that which was prevalent in paper-based packaging. Theoretically, PPA should not be on the surface of the film at the end of the manufacturing process. From my understanding (thank you in advance for sharing your understanding), the existing laws that take effect in 2023 and 2024, with the exception of Rhode Island's, do not address the use of PPAs because they do not serve an intended function for food contact. My analysis is that the PPAs in use are not going to be banned by the existing laws. Reading the laws is complicated and some are more difficult than others (e.g., the one for Maine), so thanks for your comments!

Will we change the nature of the PPAs used in flexible plastic food packaging? 

If the trend continues, I think so. We won't be surprised to see major food packaging companies announcing that their products are PFAS-free or fluorine-free. There is a real groundswell, which initially came from some retailers and brand-owners. They have certainly been very affected by the situation in paper packaging, especially at a time when it is well perceived to replace plastic packaging with paper packaging... But that is another story.

Let's be careful that such a change does not come at the expense of mechanical plastics recycling.

If change is really going to happen, should it be done in a hurry?

My opinion is no. There is a lot of work to be done for resin manufacturers and converters and many did not have an alternative solution by the end of 2022. One manufacturer is ahead of the curve: NOVA Chemicals announced in November 2022 that the company plans to transition its entire polyethylene portfolio to utilize a new processing aids free of fluoropolymers by the end of 2023. Several masterbatch manufacturers also offer non-fluorinated additives. Other resin manufacturers are lucky: they have never added fluorinated PPA to their resins.

To date, some of these new additives have restrictions on their use (film thickness, etc.). These new non-fluorinated PPAs are kept confidential and do not all seem to be based on the same chemistry. Ideally, we should make sure that the different substitutes have a good compatibility (synergistic effect) between them, otherwise it might be more difficult, without going as far as a betamax vs. VHS (yes I was born).

Finally, we need to ensure that these new PPAs do not have more environmental impacts than the fluorinated products they will replace. Who can tell us?

The information and opinions in this article are the sole responsability of the author. Please inform the author of any inaccuracies or misunderstandings.