A European Chemical Agency (ECHA) six-month public consultation period ended in September 2023. It concerned a proposal by five European Union member states to ban the sale, production, use and import of per- and polyfluoroalkyl substances (PFAS).
There were more than 5,600 comments and information submitted by 4,400 interested parties, relating to more than 10,000 PFAS types. An 18-month transition period is due once a PFAS ban comes into force.
Some five- or 10-year "time-limited derogations" beyond the 18-month period may be permitted "based on socioeconomic considerations and availability of alternatives."
Freudenberg Sealing Technologies (FST) has concerns about Fluorine Kautschuk Material (FKM) vinylidene fluoride-based vulcanized rubber and polytetrafluoroethylene (PTFE) use in many seals, and PTFE in gas diffusion layer membranes in proton exchange membrane fuel cells.
The Organization for Economic Co-operation and Development considers polymers such as FKM and PTFE — as mainly used by FST — to be "polymers of low concern." FST nevertheless commissioned Freiburg, German-based Fraunhofer Institute for Mechanics of Materials (IWM) to report on the "replacement of polymeric PFAS in industrial applications with harsh environments," which it did in 2023. FST also uses PVDF, FEP, FFKM and FVMQ as base materials for some of its sealing materials.
In its 49-page report, IWM concluded: "A full replacement of PFAS in the sealing industry is currently unfeasible without facing significant losses in material properties, performance and product longevity."
FST states: "We expect there will be very few cases, if any at all, where a [one-to-one] substitute is currently available and which meets performance, service life and other requirements for use in our products."
IWM cites polymer scientists who have concluded that "replacing FKM in propeller shaft seals is practically not realistic and will require at least many years of research."
FST has already made changes to overcome the potential ban, however, as a part of "risk mitigation efforts." It developed an OMK-PU 30500 two-piece mobile hydraulics piston seal in 17 sizes for tractors, excavators and forklift trucks in a new blue hydrolysis- and glycolysis-resistant, high-performance 98 AU 30500 thermoplastic polyurethane (TPU). It can replace most PTFE piston seals and is combined with a non-PFAS inner elastomer O-ring "energizer" seal. The IWM report states: "Pressure resistance of PTFE hydraulic seals is significantly higher than that of elastomer or TPU seals."
The new FST TPU-based seal solution can withstand operating temperatures of -35° to 120° C (-31° to 248° F) and has 20 times better leakage performance. Materials Development Manager Jürgen Hieber adds: "The material even offers a further important advantage, namely that it makes previously unfeasible low-friction and hydrodynamically optimized sealing geometries possible in future."
According to Engineering and Innovation Manager Martin Goerres, there is also interest in the new seal material in food and packaging.