Innovative Solutions: Replacing PFAS in Coatings for a Sustainable Future

By Kelly Carluccio and Catherine Vitale, Munzing

PFAS, which stands for per- and polyfluoroalkyl substances, are a class of man-made chemicals that are widely used for their water-, stain-, and grease-resistant properties. Since their introduction to industry and consumer products in the 1940s, PFAS can now be found almost everywhere as treatments and additives for coatings and other products for diverse applications including architectural coatings, textiles, non-stick cookware, food packaging, and cosmetics.

Because of their unique chemical structure, PFAS have extremely high thermal, chemical, and biological stability. This also results in high resistance to degradation, which is why PFAS are often referred to as “Forever Chemicals.”¹ In human and animal studies, certain PFAS are now linked to a growing range of serious health risks, including cancer, even at low levels.²

In response to these alarming study results, new restrictions and regulations continue to be placed on PFAS chemicals.

Depending on where you are located in the world, PFAS can be defined in multiple different ways. The definition of PFAS differs depending on the region or country. For example, the European Commission recognizes the 2021 OECD definition of PFAS.³ Some PFAS are already categorized as Substances of Very High Concern (SVHC) under REACH,⁴ and the European Chemicals Agency (ECHA) has recently published a proposal under the EU chemicals regulation REACH to restrict their manufacture, use and placing on the market, including import.⁵

In the United States, PFAS are defined by the EPA working definition.⁶ Currently in the U.S. on the federal level, many PFAS are subject to restrictive SNURs that limit their use. At the state level, PFAS are being increasingly prohibited for use in many applications. As an example, at least 11 states have started to regulate PFAS by banning or restricting their use in food packaging. Private ecolabel organizations are also reviewing their certification protocol, such as Green Seal, who has stated they will stop certifying any paints, coatings, floor care products, adhesives, or degreasers that contain PFAS.⁷

It is clear from regulations and restrictions in both Europe and the United States that PFAS will continue to be banned, and that many industries will be in need of quick and efficient alternatives to preserve all of the performance benefits that PFAS materials can bring.

As a formulator of a complete range of specialty additives, MÜNZING understands the evolving needs of our customers. Our expert personnel are available to work with you to address the growing concerns surrounding PFAS compounds with our waxes, wax dispersions and emulsions, and wetting and leveling agents. We are committed to helping you achieve your compliance and sustainability goals while preserving high performance in your products.

The two categories of PFAS materials with the most urgent need for replacement in coatings are polytetrafluoroethylene (PTFE) and fluorosurfactants. In both cases, the greatest challenge to replacement is matching the performance attributes that these fluorochemicals bring to a formulation. The keys to successful replacement are prioritizing the most critical properties that must be reproduced and that a combination of PFAS-free additives may be required to achieve these performance attributes.

Wax Alternatives to PTFE

In response to the demand for elimination of PFAS, we have developed advanced PFAS-free polymer blends that can replace PTFE by providing reduced surface friction and improving scratch and abrasion resistance, and maintaining gloss.

Coefficient of Friction (COF)

Lowering the coefficient of friction of a coating increases its surface slip and can also improve its rub and abrasion resistance. When tested in a water-based printing ink, our PTFE-free waxes CERETAN^® MX 9510, CERETAN^® MX 3110, CERETAN^® MX 9815, and CERETAN^® MX 9820 all show a strong reduction of static and dynamic coefficient of friction compared to the ink without wax, and all match the excellent performance of the PTFE-modified waxes.

Rub Resistance

As with COF testing, our PTFE-free micronized CERETAN^® waxes show similar rub resistance compared to the ones containing PTFE, and all of our tested CERETAN^® waxes show a strong improvement in the rub resistance of the water-based printing ink compared to the sample without wax.

PFAS-Free Fluorosurfactant Alternatives

Fluorosurfactants provide a variety of desired performance features in coatings. Even at exceptionally low usage levels, they can lower surface tension to help coatings wet, level, and spread more effectively, improve dirt pickup and resistance to chemicals, oils, and moisture, and improve block resistance. In order to find a suitable fluorosurfactant alternative, formulators may need to use a combination of PFAS-free additives to achieve their coating performance targets.

Anti-Block Testing

Anti-block testing was conducted in two water-based architectural paints to measure the tendency of painted surfaces to stick together or stick to another object when placed in contact with each other. After drawdowns are dried for 24 hours, 1 x 1-inch squares are cut, arranged face-to-face, and weighted with a 1,000-gram weight at ambient temperature and in a 120 °F oven for 24 hours. The weight is then removed and the samples are slowly peeled apart and rated on a scale of 0 to 10, where 10 equals perfect separation with no tack, sticking, or tearing and 0 equals complete adhesion of the two samples to each other with paper tear when separated.

In both paints, our non-PFAS wetting additive METOLAT^® 1299 showed similar anti-block performance compared to the fluorosurfactant after 24 hours at both ambient temperature and at 120 °F. Both the fluorosurfactant and METOLAT^® 1299 show significantly improved block resistance compared to the Blank paint sample with no additive.

Dirt Pickup Resistance

Dirt pickup resistance was tested in a water-based floor coating with a fluorosurfactant and with several PFAS-free MÜNZING wetting agents and wax additives. Dirt is rubbed into each dried coated piece then tested for ease of removal. The pieces are rated for dirt removal on a scale of 1 to 10, where 10 equals no staining or dirt residue.

In this coating, our PTFE-free wax dispersion LUBA-print^® 942/P shows better dirt pickup resistance in both the knock off and wipe off tests compared to the fluorosurfactant, and less discoloration as measured on a spectrophotometer.

Conclusion

Additives containing PFAS have many unique properties that make them challenging to replace in coatings, but rapidly evolving regulations and restrictions across the globe are making their replacement increasingly necessary. With prudent selection and extensive testing, MÜNZING has identified PTFE- and PFAS-free alternatives in our portfolio that can match or even exceed many of the high-performance standards set by these fluorochemicals. In addition to the CERETAN^® waxes, LUBA-print^® wax emulsions and dispersions, and METOLAT^® wetting additives mentioned here, we are continually working to identify and create innovative solutions to this and other urgent issues.

Our experts are available to develop tailored additive formulations to help you meet your critical compliance, performance, and sustainability needs. Our goal is to provide personalized solutions to maximize your product’s performance!