The clock is ticking for food manufacturers and consumer packaged goods companies who use per- and polyfluoroalkyl (PFAS)-containing materials. By January 2024 these toxic “forever chemicals” will be prohibited in the manufacturing of food contact packaging. In response, specialty chemical company Solenis and Zume, who supplies sustainable substitutes for single-use plastic, developed and open sourced what they call their recipe and manufacturing process for PFAS-free thermoformed molded fiber food service applications.
The technology enables grease, oil, and water resistance, but without the environmental and health risks associated with the red flagged family of chemicals it’s intended to replace, according to both companies.
The partners’ innovation is born through a combination of Solenis’ chemistry and Zume’s manufacturing process.
“Our goal is to eliminate not only PFAS, but single-use plastics that sit in landfills and to replace them with safe, compostable products. That’s what we are moving toward,” says Christopher Dilkus, principal scientist at Solenis.
The technology stands up fairly well to high temperature. It breaks down in compost settings within 90 days. The chemicals are approved by regulators as acceptable for direct food contact. And most fiber sources can be used in manufacturing; to name a few: virgin wood fiber from trees, fibers from mixed office waste and other recyclable paper, and fibers from agricultural waste.
The chemistry designed into this new alternative includes several components:
1) Addition of oil- and grease-resistant chemistry to the slurry before packaging is formed.
2) Water-resistant chemistry.
3) An agent to boost that chemistry’s performance.
4) A retention aid that helps hold onto the oil-, grease-, and water-resistant chemistries, as opposed to letting them leave the material with the water when slurry is converted to molded fiber.
That’s the high-level description of the chemistry. As far as the manufacturing process, Zume identified five process parameters that it had to control in order to achieve oil and grease resistance with Solenis’ formulation.
1) Thermoforming, which is a manufacturing process where it’s important to achieve high pressures and temperatures, which is key to making a denser product.
2) Freeness, which is the rate that water drains from fiber in the mold forming process; freeness is also tied to fiber length.
3) Chemical management to control how well the chemicals adhere to fiber. Considerations are addition and sequencing of chemicals, and amount of time chemicals are in contact with the fiber.
4) System charge management to control the range of charge associated with the overall slurry as chemicals are added to it. This is necessary to ensure chemicals attach to fibers rather than to fines released into water when slurry is converted to product.
5) Container formation. The goal is to prevent thin spots, ensuring uniform distribution and density.
“[Solenis’] and our work is a convergence of materials [chemistry], machinery, and process,” says Pam Horine, vice president of product research and compliance at Zume.
“Together, our companies developed strategies for chemical management. Solenis did benchtop screening, and we would take that screening to our pilot machine [to determine efficiency] in our facility. If we found a negative impact, we worked together to overcome it.
For instance, we had to run at lower freeness, which means running manufacturing lines slower. So, we found ways to modify chemistries and identify manufacturing process parameters to achieve production efficiencies at the needed lower freeness level,” she says.
Zume started as a pizza company several years ago with the intent to eliminate unsustainable practices in the food supply chain.
It developed a package for pizza that kept it fresh while directing oil that might come off of the pizza and that provided airflow that kept it warm.
“We realized we would make a larger impact if we focused primarily on packaging solutions, beyond those for pizza, that were more sustainable than single-use plastic,” Horine says.
Like Zume, Solenis’ early interest was primarily focused on its own business operations, and the interest grew from there.
“We were one of the first companies to stop selling PFAS. It was the right thing to do. Once we understood this is the direction the industry was moving in and what PFAS is doing, we said, let’s find a way to impart oil resistance in pulp and paper, without PFAS,” Dilkus says.
The decision to move away from PFAS did not happen fast because when Solenis began looking at alternatives there was no market pull. It seemed unlikely that the team would find a way to develop an economically sustainable replacement.
Once pending regulations around these chemicals were hanging overhead, the company revisited the same alternative chemistries, but there was still no fast fix.
“The idea that you could find a drop-in replacement for PFAS without changing the chemical program does not exist today. We had to do some work around chemical formulation development and chemical program development and figure out how to get all these chemical components to work together so they could perform as much like PFAS as possible,” Dilkus says.
The partners are now focused on achieving longer oil hold out times (whereby oil does not penetrate the fiber) and tolerance of hotter temperatures. At the same time, they are trying to make their technology known.
Says Dilkus: “We are talking to everyone we can across the industry supply chain, from equipment manufacturers to companies making molded fiber articles and selling them to brands and grocers so we can get the word out that we have something that can be used as a PFAS replacement.”