Bio-based coatings for exterior building materials

Exterior applications place high demands on coatings

Conventional coatings are primarily based on fossil raw materials such as epoxy, polyurethane, alkyd, or acrylic resins. While these materials offer high stability, durability, and weather resistance, they also come with significant environmental drawbacks. High emissions of volatile organic compounds (VOCs) occur during application and throughout the entire life cycle. In addition, problematic waste and the abrasion of microplastics continuously burden the environment. Although initial bio-based alternatives are already available on the market, their share of renewable raw materials usually remains well below 40 percent. The reason for this is that key chemical functions have so far been difficult to achieve using purely natural components.

Bio-based high-performance coatings with advanced functionality

The aim of the “BioCoMa” research project is to develop water-based coatings for exterior applications that can functionally replace fossil-based systems. The focus is on high moisture resistance, excellent UV stability, and long service life. The targeted use of proteins, carbohydrates, and lignin enables coatings with a bio-based content of over 80 percent. Through the intelligent modification of natural materials, these new systems outperform existing bio-based coatings in technical terms. Tailored crosslinking of proteins ensures the necessary mechanical strength of the coating. At the same time, specialized lignin-based UV blockers act as a protective shield against solar radiation and prevent premature hydrolysis of the material. Adhesion and chemical resistance can be optimized through carbohydrate-based crosslinking agents. In addition, hydrophobic bio-based additives enhance water repellency, surface quality, and improve the visual appearance. The result is sustainable coating systems that can compete with conventional paints in terms of performance and stability.

Targeted combination of bio-based binders and additives

Fraunhofer IVV focuses in particular on the development of protein-based binders and bio-based crosslinking agents. The main challenge lies in formulation development. To achieve high durability for exterior applications, researchers at Fraunhofer IVV specifically combine biopolymer binders with bio-based additives. Film formation, adhesion, water resistance, and long-term stability are precisely controlled through fine-tuning of the formulations while taking interactions into account. This makes it possible to create bio-based coating systems that can even surpass fossil-based resins in their properties.

Scaling bio-based binders from laboratory scale to market readiness

In addition to material development, industrial feasibility is a key focus of the “BioCoMa” project. The developed bio-based coating formulations are therefore designed to be fully compatible with existing manufacturing processes. Companies should be able to use their existing equipment without the need for costly modifications. To ensure consistent raw material quality, Fraunhofer IVV relies on the processing of natural residues through enzymatic and mild chemical modifications.

The international research project “BioCoMa” is embedded in a strong European consortium of German and Belgian research and industry partners. The partners complement each other with outstanding expertise in the fields of biopolymer chemistry, coating formulation, and industrial processing.