Development and characterization of a simple and fast castor oil-based polyurethane coating

This study focuses on the development and characterization of polyurethane coatings using castor oil as a renewable source. Most castor oil-based polyurethane paints have a rather long curing process. Therefore, this study focused on the preparation of a polyurethane paint based on raw castor oil without the need for chemical modifications, in a quick and cost-effective manner. The methodology involved the preparation of the paint using castor oil, isocyanate, calcium carbonate, titanium dioxide, additives and solvents. The coatings were then characterized and compared with industrial polyurethane paint in terms of thermal properties, rheology, UV degradation, adhesion, water resistance, and resistance to salt spray corrosion. Results showed that the castor oil-based paint exhibited comparable rheological behavior to the commercial paint, with superior thermal stability. However, the industrial paint showed better performance in UV degradation and similar behavior in the adhesion tests. In the water resistance test, the castor oil-based paint proved to be superior to the commercial paint. The salt spray corrosion test revealed that the castor oil-based paint had superior corrosion resistance due to the higher proportion of castor oil in the formulation, which increases the crosslinking of the chains. This work offers a simple and fast method to prepare and substitute petrochemical polyols with castor oil in order to use renewable sources with promising properties.