UV-Curable, Low-Viscosity Resin with a High Silica Filler Content for Preparing Ultrastiff, 3D-Printed Molds

Mold forming is among the most valuable methods of plastic processing and engineering due to its high accuracy and efficient throughput. However, complex processes are needed to prepare injection molds, resulting in extremely high initial investment costs. Stereolithography (SL), an emerging three-dimensional (3D) printing technique, shows promise in significantly reducing the cost of manufacturing molds while meeting requirements for mold accuracy. Nonetheless, the service life of printed molds is often limited by poor mechanical and thermal properties of compatible resins, preventing their widespread use in industrial applications. Although introducing inorganic fillers to the resin has been proved to be an effective enhancement method for the properties mentioned above, the drastically increased viscosity of the system makes it incapable of being well adapted for commercialized SL printers. Here, we overcome these challenges by introducing the vaporized metal combustion (VMC) method to prepare a high-solid-content (60 wt %) UV-epoxy/microsilica while retaining a low viscosity (1072 cps), which makes it suitable for SL 3D printing. By a laboratory-scaled SL 3D printer, as-prepared samples exhibit ultrahigh stiffness (Young's modulus of 9.72 GPa) and thermal tolerance (heat deflection temperature reaches 188 °C). We further demonstrate that with a combination of materials and the mold design, the service life of the as-prepared injection and vacuum casting mold was greatly extended (about 10 times higher than other reports). This work surpasses limitations in the properties of 3D-printed parts, enabling direct printing molds via stereolithography for potential use in academic and industrial applications alike.