Bio‐Based, UV‐Curable, Sustainable, High‐Renewable Content Polymer Formulations for Coating Applications

ABSTRACT The development of bio‐based sustainable coatings has gained significant attention due to the urgent need to reduce the environmental impact of traditional synthetic coatings. Traditional coatings often depend on fast‐depleting petrochemical resources, emit volatile organic compounds, have large carbon footprints, and are time‐ and energy‐intensive. To address this, several bio‐based options, such as modified or non‐modified vegetable oils, acids, and polyols, can be used as precursors or building blocks in the coating industry. These materials offer a promising pathway to reduce dependency on fossil fuel resources, lower carbon footprints, and meet increasing regulatory, industry, and consumer demands for sustainable coatings. The present study explores the synthesis and performance evaluation of UV‐curable coatings derived from bio‐based renewable materials, which mainly include epoxidized soybean oil, cardanol, itaconic acid, and dipentene. This study aims to design optimized formulations by regulating the properties: viscosity, hardness, gloss, impact, water absorption, adhesion, flexibility, and degree of curing. It was observed that, with an increase in cardanol content, there was an increase in the viscosity of the resin from 2400 to 5200 cPs. Additionally, the pencil hardness and gloss of the coated and cured film were improved from H to 3H and 86 to 95 GU, respectively, suggesting higher crosslinking. The impact resistance, however, was reduced with increased cardanol content, attributed to higher hardness and crosslinking. Water absorption was lower (0.0402%) for samples with higher cardanol compared to lower cardanol analogues (0.065%), which was attributed to the higher curing and hydrophobicity of the alkyl side chain of cardanol. The solvent rub test observed the same trend: that is, samples with less cardanol content showed loss of gloss for 200 rubs due to solvent absorption, while other samples remained unaffected. All the formulations in general showed good adhesion (5 B) and a flexibility pass of 7 mm. The formulations were designed to cure under UV radiation at ambient temperature by chemical modifications. The findings indicate that the bio‐based UV‐curable coatings with a very high renewable content (96%–97%) can be a viable alternative to fossil fuel‐based traditional coatings, supporting sustainable development goals, without compromising product quality or performance. The present work demonstrates their suitability, sustainability, and green and environmentally friendly approach.