ToughRubber 3D Printing Resins from Desktop Metal Aim to Break the Acrylate Mold

Though vat photopolymerization has proven to be capable of high throughput production of high-resolution parts, photopolymer resins often lack the physical properties necessary for end part applications. Desktop Metal (NYSE: DM) seeks to change this through the release of its DuraChain materials, which the company claims overcome these challenges.

Photopolymers for 3D printing are typically acrylate based, which results in brittle prints that can shatter on impact. Companies like Carbon attempt to address this issue using a two-part formula, in which additives, triggered by exposure to heat, augment the chemistries to offer better performance.

In contrast, DuraChain relies on Photo Polymerization-induced Phase Separation (Photo PIPS), in which the materials phase separate into two parts at a nanoscopic level. With a long pot life of about a year, the material can be stored for a longer period of time, as well. The materials were developed by Adaptive3D, a Texas-based startup acquired by Desktop Metal in 2021. The startup’s predecessor material, ToughRubber, was said to be able to stretch to 4.5 times its original length before recovering from the deformation.

“DuraChain photopolymers signal a new era in DLP printing that delivers material properties that compete with thermosets in a long pot-life material,” said Ric Fulop, Co-Founder and CEO of Desktop Metal. “Parts printed with DuraChain resins are high performing in a wide range of temperatures and offer other important benefits that will quickly lead to new material innovations in DLP printing.”

Traditional limitation to acrylates is in part due to the fact that most vat photopolymerization methods cannot process highly viscous materials. In part, this is because most digital light processing (DLP) machines rely on bottom-up projection, casting light through a transparent resin vat. Because more viscous materials are often heavier and require more energy, suspending them upside down on the build tray can be difficult.

Manufacturers like Fortify, Formlabs, and, most recently, BCN3D, have developed proprietary methods for processing these thicker materials. For Desktop Metal, the solution is to 3D print these materials using the Xtreme 8K system from ETEC (formerly EnvisionTEC). The Xtreme 8K projects light downward, bypassing the suspension problem.

Now, Desktop Metal is releasing its first DuraChain materials, Elastic ToughRubber 70 and 90, offering different Shore A durometer values. While the former is only available in black, the latter is available in black and white, which can be dyed for a given application.

Demonstrating the utility of the materials, industrial vacuum manufacturer Dustless Tools used the material to 3D print its DustBuddie for demolition hammers. This required a material with high energy return, tear strength, and resilience. Dustless suggests that the product, which collects dust from demo hammers, would have been cost prohibitive for injection molding, given the niche segment. However, with 3D printing, the company was able to bring the product to market.

To understand the material in greater context, we reached out to David Walker, co-founder of Azul3D and the chair of the Photopolymer Additive Manufacturing Alliance Executive Advisory Board. About the material, Walker said:

“I think the move away from two-part resins is critical—it’s what consumers are demanding. That being said, PIPs isn’t all that new of an idea. There are multiple resin formulators already using these types of techniques and I think it’s just not generally advertised or known. It will certainly help improve the materials portfolio at Desktop Metal, but we would need to see the material spec sheets to see what kind of impact this will really have on the market. Also, Desktop Metal and [ETEC] don’t have great hardware paths for printing higher viscosity resins, like the new BCN3D photopolymer printer or Formlabs’ innovative Form 3 and 3L. Without these types of hardware innovations, there will still be bottle necks.”

Regardless of Desktop Metal’s specific products, the news does reflect a change in the market in which a wider variety of photopolymers are being introduced. Along with the companies already mentioned, Inkbit has expanded beyond acrylates. This will certainly mean greater advances in the field, as well as greater adoption and much broader applications for vat photopolymerization.