Development of Sealers for Corrosion Protection Based on Biogenic Raw Materials

Due to their porosity and roughness, thermally sprayed coatings require sealing and are treated with sealants for effective corrosion protection in accordance with DIN EN ISO 2063. Since these sealants must be low-viscosity for good infiltration and often form only a thin, not completely covering film, overcoating in the system is common practice in accordance with DIN EN ISO 12944-5. The article describes the development of a bio-based 2K-PUR sealer with a 34 % bio-based content, whose adhesion and paintability are adjusted using suitable polyols, crosslinkers and additives (leveling/defoaming). Adhesion tests as well as exposure and salt spray tests confirm good corrosion protection performance; applicability up to “C5-M High” is derived.