Itaconic Acid-Based Reactive Diluents for Renewable and Acrylate-Free UV-Curing Additive Manufacturing Materials

Reactive diluents, small monomers with low viscosity, and reactive groups are widely used in UV-curable materials for additive manufacturing (3D-printing) to optimize the processability and properties of the cured objects. Most of these reactive diluents, such as acrylic acid esters, are derived from fossil resources and possess strong irritation and allergenic potential. Therefore, more benign bio-based reactive diluents for UV-curing materials are of high interest. Herein, we present the synthesis of novel monomeric compounds derived from bio-based itaconic acid, such as diesters and hydroxyesters. Depending on the molecular architecture, the viscosity and reactivity can be significantly influenced. The most promising monomers were formulated with bio-based polyester itaconates and the properties of the materials were evaluated. The addition of these reactive diluents resulted in a significant reduction of the viscosity and an improved curing behavior. Finally, two of these novel reactive diluents were successfully applied in UV-curing additive manufacturing processes.