Functional Equivalence Requires Similar Purpose 

The claims on appeal in Shooshtari were drawn to a binder composition that included “a catalyst for catalyzing a crosslinking reaction between the reducing sugar and the crosslinking agent, wherein the catalyst comprises a sulfonic acid compound.” The primary reference relied on by the Examiner disclosed a binder composition that included a pH adjuster, such as HCl, for preventing unwanted polymerization, but it did not disclose the presence of a sulfonic acid compound.

To remedy this deficiency the Examiner relied on a secondary reference that taught a binder composition containing a mineral acid catalyst, such as HCl or p-toluene sulfonic acid, to effect crosslinking reactions. According to the Examiner, it would have been obvious to replace the HCl pH adjuster of the primary reference with the sulfonic acid polymerization catalyst of the secondary reference. The Board disagreed.

In particular, the Board found that the primary reference taught HCl for the sole purpose of adjusting the pH to inhibit unwanted polymerization, while the secondary reference taught HCl and sulfonic acid as acid catalysts to effect crosslinking reactions–a completely different purpose. Consequently, the Board held the Examiner failed to identify a reason why a skilled artisan would have sought to include the acid catalyst of the secondary reference in the composition of the primary reference.

Takeaway: Shooshtari shows the value in analyzing the purpose of each component of a composition when facing an obviousness rejection that relies on functional equivalence. The purpose and function of the components ties into whether there is an apparent reason to modify the prior art in the manner proposed by the Examiner. Here, the purpose of the components in each of the references was contradictory to the other such that a skilled artisan would not have had a reason to equate and replace them. Accordingly, when facing a rejection that relies on functional equivalence it is important to fully assess the purpose and function of the components involved.

Judges: T. Ownes, W. Wilson, J. Snay