For years, polytetrafluoroethylene (PTFE) has brought a number of desirable properties for traditional ink and coating applications, such as broad spectrum chemical resistance, resistance to water and solvents, a slippery surface, resistance to degradation when exposed to UV light, unusually high molecular weight and melt point, and it did not flow above its melt point
Development over its first three decades exploited the chemical resistance and stability of PTFE while further refining its handleability, processability and strength properties by copolymerizing with other monomers like hexafluoropropylene, ethylene or other fluorinated monomers.
Low molecular-weight PTFE micronized powders have been used for a variety of purposes, including to reduce the coefficient of friction of the film to aid mobility and to lubricate and protect surfaces from scratch and abrasion forces. To achieve low-molecular weight and friability has typically required irradiation to enable particle size reduction using conventional micronization techniques.
However, in recent years, PTFE has come under some scrutiny and driven the exploration of PTFE-alternatives.
Regulatory Actions Impact PTFE
PTFE stability properties that have driven use in many applications also impact cradle-to-cradle policies. The irradiation process has been demonstrated to generate PFAS components, with PFOA and PFOS both classified as reproductive toxins and suspected carcinogens. While PTFE itself is not regulated, PFAS components are regulated in Europe (July 4, 2020 EU REACH restriction effective date) and regulations limiting the quantity of PFAS materials are pending in other regions of the world.
In this global regulatory environment, there are essentially two alternative approaches: use PFAS-free (compliant) PTFE or develop new products without PTFE.
Lubrizol is taking both of these approaches—PFAS compliant PTFE and PTFE-free alternatives—to have products in place before the July 4 restriction date in the EU. Formulations with reduced levels of PTFE have shown promise, as has a new non-halogen, proprietary material being used in place of PTFE.
A PTFE-Free Alternative
Testing of the new non-halogen material in a water-based phenolic-melamine gold lacquer demonstrated strong sheen scratch resistance and good Sutherland rub resistance while maintaining 60° gloss. Testing of a clear overprint varnish with this new material has also demonstrated strong sheen scratch resistance and good Sutherland rub resistance without reducing 60° gloss.
Phenolic-Melamine Gold Lacquer, Water-Based
Clear Overprint Varnish, Solvent-Based
At Lubrizol, we will continue testing and looking for PFAS-compliant PTFE options and PTFE-free alternatives, but are excited by the results to date in creating a new material that has shown promise to be used in place of PTFE for decreasing the coefficient of friction, increasing slip, and improving abrasion and rub resistance.
Contact your Lubrizol account manager to explore collaboration opportunities for PTFE alternatives for your coating challenges.
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