Carbon's Foundational Dual-Cure 3D Printing Patent Survives EPO Appeal

EPO Decision Confirms Core AM Technology

Carbon announced on September 28 that a Board of Appeal at the European Patent Office (EPO) rejected a competitor's challenge to European Patent No. 3158400, which covers methods for producing 3D printed objects using materials with multiple hardening mechanisms.

The EPO Board of Appeal considered the case on September 24, 2026 and upheld the patent's broadest claim, affirming an earlier EPO Opposition Division decision that had maintained claim 1. The board also reinstated additional dependent claims that had previously been removed during the original opposition.

Carbon's dual-cure technology combines light-based 3D printing with a secondary thermal curing reaction. This approach produces parts with properties tailored to each application, including engineering-grade strength, elasticity, durability, and temperature resistance. The technology underpins Carbon's Digital Light Synthesis (DLS) platform.

Industry Impact

The dual-cure chemistry is used across end-use production applications in automotive, dental, medical, and consumer products. Carbon noted that the ruling validates the strength and breadth of the innovation foundational to its platform.

Philip DeSimone, Carbon's co-founder and CEO, said the decision confirms the company's commitment to advancing digital manufacturing and that Carbon will continue investing in and protecting its innovations.

Legal Landscape

The challenge was filed by Oxon IP B.V. on behalf of an unnamed competitor in 2023. In 2025, the EPO's Opposition Division maintained the patent in amended form, but removed some dependent claims. Both sides appealed. The Carbon decision comes as several major AM companies face legal battles, including a Texas jury awarding Stratasys $27.6 million after finding Bambu Lab infringed four of its patents.

Image: Adidas midsole produced on Carbon's L1 3D printer. Source: Carbon via 3DPrint.com.