A novel UV-curable hyperbranched polyester-urethane-acrylate (PUA) resin was successfully synthesised using citric acid as a core bio-based material and ester-urethane-acrylate linkage as the arm and was applied on both wood and metal substrates.
Citric acid was employed as a functionality-enhancing bio-based monomer for coating applications. This resin (PUA) was synthesised from citric acid (CA)-based polyester-polyol (CAP) and subsequently reacted with isophorone diisocyanate (IPDI) and end-capped with 2-hydroxyethylmethacrylate (HEMA) to form a tetra-functional acrylate precursor (UCAP). This oligomer was formulated with a reactive diluent and a photoinitiator (UCAP PUA), applied on both wood and metal substrates and cured under UV-radiation.
Superior thermal properties
The mechanical, chemical and thermal properties of the coated substrates were investigated and compared to a commercial urethane acrylate (CUA). The mechanical properties such as crosscut adhesion, pencil hardness, impact strength and flexibility showed comparable results. Even though the chemical resistance and free film properties of the synthesised urethane acrylate (UCAP) were found to be inferior, the thermal properties were observed to be superior.
The study has been published in Journal of Coatings Technology and Research , Volume 20, Issue 3, May 2023.
Event tip
Bio-based systems are also the focus of the EC Conference Bio-based and Water-based Coatings on November 14 and 15 in Berlin, Germany. At the conference, you will learn about the latest developments in bio-based and water-based coatings.