PFAS-free, wear-resistant, and energy-efficient: Through the new research project “PTFE-Sub,” the SKZ Plastics Center and INNOVENT e.V. are developing innovative sol-gel coatings for plastic welding. The goal is to create sustainable alternatives to established coating solutions without compromising on performance or process reliability.

Performing a heating-element butt weld on PA-U 12 pipes using a PTFE-coated heating element. (Photo: Luca Hoffmannbeck, SKZ)

Sustainable sol-gel coatings for longer service life and lower energy consumption

The “PTFE-Sub” research project, a forward-looking initiative to develop novel non-stick coatings for plastic welding, was launched in August 2026. The goal of the project is to replace the polytetrafluoroethylene (PTFE)-based coating systems—which have been widely used to date—with PFAS-free, durable, and energy-efficient alternatives based on sol-gel technology. The project is being carried out jointly by SKZ and INNOVENT e. V.

PTFE coatings and PTFE-glass fabric films have proven their worth in numerous plastic welding applications. In particular, they provide good non-stick properties in heating-element butt welding of plastic pipes made of polypropylene (PP) or polyethylene (PE) and window profiles made of polyvinyl chloride (PVC). PTFE is also used as a material for welding shoes in hot-gas extrusion welding. At the same time, however, PTFE-based solutions are increasingly reaching their limits: Their comparatively low wear resistance leads to frequent maintenance and replacement intervals. In addition, PTFE and other PFAS-containing materials are coming under increased scrutiny due to potential future regulatory restrictions.

Easy Repair and Recoating of Molding Tools
The PTFE-Sub project addresses precisely this issue. The goal is to develop innovative sol-gel coatings that combine high temperature resistance, outstanding non-stick and sliding properties, and significantly improved wear resistance. In addition, the new technology is intended to enable easy repair or recoating of the tools, thereby further extending their service life.

“With PTFE-Sub, we want to demonstrate that high-performance non-stick coatings are possible even without PFAS. Our goal is to provide companies with a sustainable and economically attractive alternative to today’s PTFE systems,” explains Patrick Witzel, head of the Thermal Joining research group at SKZ.

The research focuses on novel sol-gel systems that are specifically tailored to the requirements of various welding processes through the use of suitable additives. In addition to developing the coatings, extensive test setups are being established to investigate wear, non-stick, and sliding properties under realistic conditions. Furthermore, the coatings are to be validated in practical welding trials using PE and PVC components.

Numerous Benefits for Users
This results in numerous benefits for users. The goals include longer tool service life, lower maintenance costs, and greater process reliability. At the same time, the use of PTFE fabric films and PTFE welding shoes—which are difficult to recycle—is to be replaced by durable alternatives.

The research results are aimed in particular at small and medium-sized enterprises in the fields of plastics processing, piping construction, window manufacturing, apparatus and container construction, and surface technology. Furthermore, the project partners see potential for applications in other industrial sectors where temperature-resistant and non-stick surfaces are in demand.

Funding
The two-year research project is funded as part of the Joint Industrial Research (IGF) program (01IF25312N). The project partners expect that the coating systems developed will make an important contribution to the substitution of PFAS in industrial welding processes while simultaneously strengthening the competitiveness of small and medium-sized enterprises in particular.

More information on surface technology
More Information on plastic welding