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New approaches for Polyurethane-coatings – from DTM to isocyanate-free systems
PU coatings are indispensable in many industries — yet they face clear limitations. Significant gaps remain, especially in water-based systems and direct-to-metal applications. Dr. Chintankumar Jayanthilal Patel spoke with European Coatings editor Bettina Hoffmann about how BASF aims to close these gaps with new polyols, high-gloss dispersions, and sustainable concepts — and why the quest for isocyanate-free PU systems is far from over.
How does the trend towards bio-based coatings influence PU development?
Dr. Chintankumar Jayanthila Patel: Polyurethane (PU) coatings have long been a cornerstone of high-performance industrial coatings. In recent years, the push for more sustainable coating technologies has gained noticeable momentum, with bio-based coatings and the biomass balance approach both emerging as key strategies within the industry.
The current PU coating market is primarily driven by a price-performance equilibrium, which means that the development of bio-based PU coatings focuses on incorporating bio-based carbon content without compromising technical performance or affordability.
Opinions on 14C traceable carbon content and the biomass balance approach vary across different segments, with BASF being one of the key players pioneering the biomass balance approach. Depending on the sustainability goals of various organizations, one method may be preferred over the other or a combination of both; for instance, certain OEMs prioritize achieving at least 50% 14C traceable carbon of total better carbon content of their coatings. These strategies are pertinent to both solvent-based and water-based PU coatings.
At BASF, we offer raw materials that deliver technical performance while incorporating sustainable carbon content or leveraging biomass balance. Therefore, we believe that the trend towards bio-based coatings will be one of the influencing factors in polyurethane developments towards greater sustainability, while ensuring a careful balance of price and performance.
Do you see any gaps in PU products and how are you addressing them?
Patel: In the last several decades, polyurethane (PU) coating technology has evolved significantly, becoming a workhorse of the coatings industry. It is widely used in OEM, refinish, industrial, and even architectural coatings. While primarily developed for topcoats due to their excellent optical, mechanical, and weathering properties, there remains a gap in PU coatings for the direct-to-metal (DTM) segment, where they can be used as primers or in monocoat systems that serve the dual purpose of both primer and topcoat.
Recently, some products have emerged in this area, but ample opportunities exist for further development. In water-based (WB) PU coatings, despite many offerings, a performance gap compared to solvent-based (SB) counterparts has persisted due to intrinsic challenges of WB technologies. Therefore, there is significant potential for advancements in WB PU coatings, particularly in achieving higher performance (closer to SB), glossy fast-drying coatings and DTM applications. At BASF, we are addressing these gaps by developing new polyols for both WB and SB 2K PU DTM coatings.
We have also innovated aqueous polyol primary dispersions suitable for high-gloss 2K PU topcoats and high-build WB PU coatings. Additionally, there is an enduring quest for non-isocyanate PU coatings. Although various chemical routes have been demonstrated in research, they do not match the cure profile and viability of conventional PUs, making this an intriguing area for future research and development.
