EPA P2 2018

Our 2018 US EPA Pollution Prevention (P2) Project

Developing and performance testing a safer formulation for stereolithography printing resin.

US EPA Region 9 Business-Based Pollution Prevention Solutions Supporting Toxic Substances Control Act (TSCA) Priorities and Chemical Safety (2018-2021)

Additive manufacturing has had the disruptive potential to increase industry sustainability with just-in-time manufacturing, reduction and recycling of waste, and the reduction or elimination of transportation and inventory costs by decentralization of production. Current material use, processing and disposal, however, come with some significant drawbacks and chief among them is the presence of chemicals of concern in the formulations of resins and inks.

Once such family of chemicals are the acrylates and methacrylates which do such a good job of consistently cross-linking other chemicals within UV activated 3D printing processes, but present problems to human and environmental health, such as skin sensitivity and aquatic toxicity.

In 2015, BCGC partnered with the software manufacturer Autodesk to assess the relative safety of a resin formulation used in their demonstration printer, the Ember, as part of their Spark program of open platform sharing of data for both its hardware and software. This was done to encourage crowd-sourced innovation in a field where 3D printing patents and IP protection had seemed to slow progress toward easier adoption and widening applications. The resin that Autodesk was using was PR48, developed by Colorado Polymeric Systems, and the BCGC team assessed this formula and the many other chemical alternatives typically used in stereolithography printers. This work led to further work by a BCGC intern hosted by Autodesk and Northwest Green Chemistry, a series of industry user feedback roundtables, and an alternatives investigation by BCGC’s 2016 Greener Solutions graduate course.

The cumulative results of this work brought the realization that more appropriate and comprehensive metrics were needed to compare chemical alternatives specific to the field of additive manufacturing, and that a concentrated effort to develop a testing procedure would be a boon to the industry. In 2018, BCGC applied for and received support from the US EPA Region 9, to pursue this effort.

Specifically, the purpose of this project was to produce and disseminate a replicable best practices methodology for chemical hazard assessment of stereolithography (SLA) printing resins, that could be used toward a set of standards for formulation of safer resins and the testing of actual alternative formulas.

To accomplish this the Berkeley Center for Green Chemistry (BCGC) has collaborated with a range of partners across academia, industry and non-profit organizations and individuals during the three years of this project. The initial project team comprised BCGC, Northwest Green Chemistry, Chemist Justin Bours, Mechanical Engineer Jeremy Faludi of Dartmouth College and then Technical University of Delft, and the St. Louis and Milwaukee branches of the Millipore Sigma chemical manufacturing company. Later phases of the project included engagement with ChemForward, Radical Curing LLC, Radtech, an additive manufacturing trade group, and the National Institute of Standards and Technology (NIST) of Boulder, CO. The BCGC team has included Tom McKeag, executive director and principal investigator, Dr. Tala Daya, senior researcher, Dr. Rachel Scholes, Nicole Panditi, and Kimberly Hazard.

The results have been part of a continuing conversation with the additive manufacturing sector at large that may help transition the industry away for harmful chemicals, and toward greater transparency of formulas and wider adoption of chemical testing methods at the formula design stage. The team has completed a review of additive manufacturing formulas in stereolithography, material extrusion and jetting and bioinks, developed a chemical hazard assessment scorecard, and distributed that scorecard for review by a spectrum of professionals. BCGC is currently compiling our results for a final report and the production of outreach materials, due by February, 2022.