Preparation of isotropic tensile photosensitive resins for digital light processing 3D printing using orthogonal thiol-ene and thiol-epoxy dual-cured strategies

Poor layer interface adhesion leads to increasing anisotropic properties and weakening tensile properties of 3D printed parts. In order to reduce anisotropic properties and enhance the tensile properties of thiol-ene light-sensitive resins for Digital light processing (DLP) 3D printing, thiol-ene-epoxy hybrid resins containing a radical initiator (TPO) and photobase generator (TBD-HBPh4/ITX) were prepared to reduce the anisotropy and enhance the tensile properties of thiol-ene light-sensitive resins for digital light processing (DLP) 3D Printing. Real-time Fourier transform infrared spectroscopy (RT-FTIR) indicated that the CC bond conversion of resins exceeded 60%, and the thiol conversion was approximately 50%. The volumetric shrinkage of the thiol-ene resins increased to an extent with thermal treatment, indicating that these resins had undergone postcuring. Dynamic mechanical analysis showed that the glass temperature (Tg) increased from 20.8 °C to 34.1 °C. The tensile strength of the 3D printed part increased by approximately 500% with each printed orientation, and the degree of anisotropy with each orientation reduced by less than 5%. It was confirmed that the superior isotropic properties of the thiol-ene photosensitive resins for DLP 3D Printing were obtained using orthogonal thiol-ene and thiol-epoxy dual-curing strategies.