Optimization of vat photopolymerization resin formulation for digital light processing three-dimensional printing of Si3N4 ceramics

This study aims to optimize the formulation of vat photopolymerization resin for digital light processing (DLP) three-dimensional (3D) printing of Si₃N₄ ceramics to address the challenges posed by their high refractive index. Initially, we evaluated nine commonly used monomers and selected acryloyl morpholine, propoxylated neopentyl glycol diacrylate, and trimethylolpropane ethoxylated triacrylate based on their quantitative performance. We then employed a formulation experimental design to determine the optimal monomer ratio of 25:60.9:14.1. Furthermore, we optimized the prepolymer (epoxy acrylate) and plasticizer (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) contents to minimize monomer shrinkage, selecting optimal values of 20 wt.% and 10 wt.%, respectively. Based on these optimizations, we determined the ideal concentrations of photoinitiator, dispersant, and thixotropic agent to be 3, 2, and 2 wt.%, respectively. Finally, using the optimized resin formulation, we prepared a high-solid-content Si₃N₄ slurry and successfully printed high-precision, complex Si₃N₄ green structures. This demonstrates the practical applicability of the optimized vat photopolymerization resin formulation, laying a solid foundation for the development of Si₃N₄ ceramics in DLP 3D printing.