Greener Solutions 2019: Stereolithography (SLA) resins

Acrylates are used as very effective cross-linkers in the polymerization of liquid resins used in stereolithography (SLA) printing. When UV light is shown on reactive monomers or oligomers in the liquid resins, they bond together to form a solid object and a typical SLA printer will build up a solid object, layer by layer, using this chemical reaction.

Acrylates and methacrylates present some human and environmental health problems, however. In use in the baseline study resin these chemicals were shown to be skin and eye irritants, skin sensitizers and aquatic toxicants.

The SLA team identified five strategies to reduce or replace (meth)acrylates in SLA printing resins: the employment of functionalized biopolymers, the use of click chemistry, pH-induced photo-polymerization, the photo-polymerization of unmodified proteins, and novel encapsulation techniques.

For each strategy, the team proposed a photopolymerization process and gave example materials for use in resin formulas. They also considered additional steps that could be taken to enhance the properties of objects printed with their proposed strategies; for instance, using post-print curing or additives to enhance strength. Finally, they provided an overview of how each strategy addressed human health and environmental criteria while promising adequate technical performance, and proposed steps that industry leaders could take to further develop these strategiesFinal ReportFinal Report