T 0377/25 — EPO Finds Organic Binder an Obvious Alternative for Abrasive Patent

Background

European patent EP 3 240 655 concerns bonded abrasive articles containing nanocrystalline alumina particles. The patent proprietors, Saint-Gobain Abrasives and Saint-Gobain Abrasifs, defended an amended main claim requiring an organic bond material and nanocrystalline alumina with an average crystallite size between 0.01 and 0.15 microns.

Two opponents appealed after the EPO Opposition Division maintained the patent in amended form. They argued that example 6 of an earlier patent publication, D7, already disclosed an abrasive disc using nanocrystalline alumina, and that substituting a known organic binder for D7’s inorganic binder was an obvious alternative. The proprietors disputed both whether D7 disclosed the claimed crystallite size and whether a skilled person had any reason to change the binder system.

The Court’s Holding

The Board of Appeal set aside the Opposition Division’s decision. It first allowed the inventive-step challenge based on D7 because the substance of that objection had been raised and discussed below. The Board also read the claim’s use of “comprising” to permit additional abrasive materials: the specified crystallite-size limitation applied to the nanocrystalline alumina, not necessarily to every particle in the abrasive mixture.

On inventive step, the Board treated the choice of binder as the decisive difference. D7 did not present its inorganic binder as technically essential, while other prior-art references taught organic binders for abrasive articles. Because vitrified, metallic, and organic bonds were known alternatives and the patent owners had not tied the organic binder to a special technical effect, a skilled person seeking another binder system would have considered the organic options without needing a separate pointer to combine the references. The main claim therefore lacked inventive step under Article 56 of the European Patent Convention.

The Board did not finally revoke the patent. The Opposition Division had not ruled on the proprietors’ fourteen auxiliary claim requests. Deciding all of those requests for the first time on appeal would impose an undue burden and deprive the parties of a meaningful first-instance examination. The Board therefore remitted the case for further prosecution.

Key Takeaways

• When a claimed substitution is a familiar, technically equivalent option and produces no demonstrated special effect, the EPO may find it obvious without requiring an explicit prior-art instruction to make the swap.
• Open-ended “comprising” language can prevent a patentee from narrowing a claim during argument to exclude other components that the text does not actually exclude.
• A successful appeal against a main request does not necessarily end the patent. Unexamined auxiliary requests may return to the Opposition Division when resolving them on appeal would be disproportionately burdensome.

Why It Matters

The decision is a practical warning for patent drafting and opposition strategy. Merely selecting one member of a known set of interchangeable materials may not support inventive step unless the specification and evidence connect that choice to a credible technical advantage. Patent owners should also ensure that fallback claim sets are developed clearly in the first-instance record, because a remand preserves another chance but adds time and expense for every party.