Fig. 1: a Schematic presentation of the requirements for a photoinitiator for a VIS light-curable yet VIS wavelength-transparent 3DP resin.
From: A visible light-curable yet visible wavelength-transparent resin for stereolithography 3D printing
b Photoinduced cleavage reaction of diphenyl(2,4,6-trimethlbenzoyl) phosphine oxide (DPTBP, left) and UV/VIS absorption spectra (right panel) of DPTBP (black) and transparent UV-curable Irgacure 2959 (red). The red box represents the weak VIS wavelength absorbance of DPTBP from 400 to 420 nm. c Chemical structures of the main resin components, namely, the polymerizable monomers PETA and HDA (top). Transparency and curability of two resins of Irgacure 2959/PETA/HDA and DPTBP/PETA/HDA (UVIStar) under a UV lamp (top row) or a VIS light lamp (bottom row). The red arrow indicates the liquid state of Irgacure 2959 resin under a VIS light source. d–f Schematic representation of the compression test for maximum load analysis (d). Comparison of the maximum load of UV (e) or VIS light (f)-cured objects for resins with 1 wt% (black bar) and 5 wt% (white) Irgacure 2959 and DPTBP in UVIStar (gray)
