Coatings are essential in modern society, providing protection, aesthetics, and functionality to various materials. Chemically cross-linked thermosetting materials are widely used for their mechanical strength and stability against chemicals and high temperatures [1]. UV-induced curing of these materials is efficient in energy consumption, reaction time, and reducing volatile organic compound (VOC) emissions [2]. While UV-curable coatings are popular for wood, glass, and plastic [3-7], their application on metal is limited due to poor adhesion, which is vital for corrosion protection [8]. Thus, improving adhesion between UV-curable coatings and metals is crucial for corrosion prevention. 
Lignin, a bio-based compound from wood, offers excellent anti-corrosion properties and adhesion to metals [9, 10]. Its aromatic structure adds rigidity, and its hydroxyl functional groups allow for material modification and tailoring of material properties [11]. However, conventional technical lignins absorb UV light, complicating their use in UV-curable formulations [12] and synthesis of UV-curable coatings with a high lignin content remains scarce. 
This study explores a novel lignin isolated through a cyclic organosolv process, which is less colored and has lower UV absorption than conventional technical lignins [13, 14]. UV-curable films were created by functionalizing the lignin with diallyl carbonate and using UV-induced thiol-ene chemistry for cross-linking. Characterization techniques such as NMR, SEC, and FTIR confirmed successful functionalization and the formation of thermoset films containing 68% functionalized lignin. Mechanical testing indicated that curing parameters significantly affect the films’ thermomechanical properties. These results highlight the potential of modified lignin for sustainable, high-performance UV-curable coatings, paving the way for broader applications in corrosion protection and beyond.