TDI-Based Urethane Diacrylate Reinforced Silicon-Acrylate Resins for LCD 3D Printing

In this study, silicon acrylate resins were formulated using a 1:1 ratio of silicon diacrylate and dipropylene glycol diacrylate (DPGDA) as the control sample (Si-HTH0), previously tested in earlier work. To enhance mechanical properties, a novel diacrylate monomer, HEMA-terminated TDI-based urethane (HTH), was synthesized by reacting toluene diisocyanate (TDI) with 2-hydroxyethyl methacrylate (HEMA). The synthesized monomer was blended with DPGDA at varying concentrations (20–100%) and integrated into the silicon diacrylate resin. Mechanical characterization revealed significant improvements in tensile strength, Young’s modulus, impact resistance, and hardness. At 60% HTH (Si-HTH60), the material exhibited the best balance of properties, with a 393% increase in ultimate tensile strength, 11.87% elongation at break, and 3.7 kJ/m² impact resistance. SEM analysis confirmed that Si-HTH60 displayed the most ductile fracture morphology among the tested samples, characterized by rougher surfaces, a distinct river-like pattern, and deep fractures, indicating enhanced energy absorption. In contrast, the 100% HTH sample exhibited a unique morphology with a fibrous and slightly porous structure, leading to the highest tensile strength and modulus, though without superior impact resistance. These findings highlight HTH’s effectiveness in enhancing silicon acrylate-based resins for advanced DLP/LCD 3D printing applications.