Volatile Organic Chemical Emissions from Standard and “Eco” Resins for Vat Photopolymerization Additive Manufacturing (“3D”) Printers and Potential Mitigation Strategies

Abstract

The chemical profile and magnitude of emissions from vat photopolymerization (VP) 3D printers, in which a liquid resin cures into a solid upon exposure to ultraviolet light, are understudied. Here, six Volatile Organic Chemicals (VOCs) were identified in emissions from an entry-level VP printer using both Standard and “Eco” resin formulations and quantified in four phases of the VP printing process. To the best of our knowledge, this work is the first to assess emissions of “Eco” resins. Two shapes were printed to assess the impact of the surface area on emissions. Emissions were greatest for two monomers, 2-hydroxyethyl acrylate and 4-acrylomorpholine. Mesitaldehyde, tolylene-2,4-diisocyanate, 2,6-di-tert-butyl-p-cresol, and dipropylene glycol diacrylate emissions were more consistent. Generally, Standard resin emissions exceeded Eco resin emissions. Object surface area did not have a clear impact on emissions. Similar or higher emissions from idle printers with an uncovered resin vat compared to emissions from active printing were observed. For the first time, it was demonstrated that idle printer emissions were reduced drastically (by 70–97%) using a fabricated vat lid, demonstrating the importance of a sealed resin vat to reduce VOC emissions. Where available, reference exposure limits for the VOCs measured were compared with total emissions; this analysis indicated that these emission rates lead to exposures approaching or exceeding available exposure thresholds. These results show that a simple mitigation strategy and, to a lesser extent, the use of a low-VOC resin should lower the emissions of VP printers and, as such, reduce VOC exposures for the users of VP Printers.