Arlanxeo and Mitscherlich get Zeon battery binder patent revoked in Germany

Zeon and Arlanxeo are two key players in the synthetic rubber market. The patent-in-suit, EP 3 800 714 and owned by Zeon, protects materials designed for use as binders in the cathodes of rechargeable batteries.

Japan-based patent holder Zeon accused Dutch company Arlanxeo, a subsidiary of Aramco, of infringing EP 714 with its synthetic rubber products. It brought proceedings against Arlanxeo at Munich Regional Court in August 2024 (case ID: 21 O 9713/24). In response, Arlanxeo, based in The Hague, filed a nullity action at the German Federal Patent Court (case ID: 3 Ni 1/25).

Court confirms opinion

In a preliminary opinion in July 2025, the patent court expressed doubts as to whether the claimed invention had been sufficiently disclosed, indicating that the technical teaching might not be reproducible. On this basis, the 21st Civil Chamber of the Munich Regional Court, presided over at the time by judge Georg Werner, decided to stay the infringement proceedings pending the outcome of the nullity action.

The Federal Patent Court has now revoked the patent in its entirety on the grounds of insufficient disclosure and added matter. The panel of the 3rd Senate, presided over by judge Walter Scharamm, confirmed the preliminary opinion.

An appeal against the decision is possible.

This will have an impact on the pending infringement case, which is now in the hands of presiding judge Hubertus Schacht, following Werner’s transfer to the UPC.

df-mp vs Mitscherlich

Zeon instructed a team from patent attorney firm df-mp. Renowned patent attorney and partner Elisabeth Greiner, together with Holger Schimmel, acted for the Japanese client in the nullity proceedings. They also handled the technical aspects of the parallel infringement proceedings.

At Munich Regional Court, a team from Morgan Lewis & Bockius represented Zeon. Alexander Ritter, a leading partner based in Munich, and associate Moritz Sutterer worked on the case. Ritter and Sutterer both joined the firm in early 2025, having previously worked at Baker McKenzie.

A mixed team from Mitscherlich filed the nullity action on behalf of Arlanxeo. Litigator Markus Bölling and patent attorney Sebastian Strych led the case for the Dutch claimant and represented them in the parallel infringement proceedings at Munich Regional Court. They worked closely with in-house counsel Thiemo Marx, Global Head of IP, and senior IP counsel Lars Müller.