Digital light processing 3D printing of multi-materials with improved adhesion using resins containing low functional acrylates

Abstract

Digital light processing (DLP) 3D printing has received increasing attention due to high-resolution printing capability, mass productivity, and cheap equipment cost. Most of all, the layer resolution less than 50 µm overwhelms 200–300 µm layer resolution of its competitive technology, filament deposition modeling (FDM) 3D printing. Despite the advantage of the high resolution, weak mechanical properties of DLP 3D printouts have limited their industrial use. One of the easiest ways to improve mechanical property is the use of multi-materials that complement each other’s weak property However, DLP 3D printing of multi-material printouts with reliable adhesion has been largely unexplored. In this study, we compared the mechanical properties of four pairs of multi-materials consisting of two different materials of the same thickness. A composition with highest modulus and ultimate strength was fixed as the first half layer, and the acrylate of the composition for the other half layer was modulated with a monomer having a functionality between 1 and 3. If the acrylate monomer’s functionality for the other half layer was less than three, the multi-material printout showed nearly averaged mechanical property of each material. We speculate that low functional acrylate with lower viscosity allows sufficient polymerization at the interface, enabling reliable adhesion. This approach that enables successful multi-material printing with improved adhesion and complementary mechanical properties will extend the use of DLP 3D printing in a broad range of industrial application that requires both sophisticated shape and mechanical strength.