Photocure additive manufacturing, such as stereolithography, continuous liquid interface production, and digital light projection, have increased in popularity due to its excellent resolution, low porosity, and low defect concentration. Yet, photocure AM resins generally have low to moderate moduli and glass transition temperatures, making these poor choices for structural applications. We have thus developed improved (meth)acrylate resins for photocure additive manufacturing relative to commercial resins through formulation of commercial and new monomers. Prior to use in additive manufacturing equipment, we began identifying optimum formulations through examination of rheological properties of the resins, and thermal and mechanical properties of the polymers after photocure. Using this, we determined that use of approximately 25 wt% reactive diluent, isobornyl acrylate or acryloylmorpholine, is ideal. The use of reactive diluent in general is critical to maintaining low viscosities and increasing the extent of cure and strength of the resulting materials. Isosorbide methacrylate also reduced the resin viscosity while increasing the glass transition temperature significantly, but caused the materials to be more brittle when used as the sole crosslinker. Commercial urethane acrylate oligomeric crosslinkers, such as Allnex Radcure Ebecryl 4859, were ideal in increasing the strength of the resin. Ideal formulations comprised of isosorbide methacrylate, Ebecryl resins, and acryloylmorpholine were then cured on the Formlabs Form 1 Plus, steroelithography instrument. Additive manufacture of these resins produces similar properties relative to photocure and improved properties relative to commercial SLA resins.

Photocurable resins for additive manufacturing

2019 Spring National Meeting

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