On May 27, 2015, the Board issued a final written decision in Organik Kimya AS v. Rohm & Hass Co., IPR2014-00185, confirming the patentability of all challenged claims of U.S. Patent No. 6,020,435.

The ‘435 patent is directed to a chemical process for preparing low-density “hollow” or “voided” multi-stage emulsion polymers used in coating compositions such as paints. These emulsion polymers are generally prepared by swelling a core/shell emulsion polymer in such a way that one or more voids form in the interior of the emulsion polymer particle. One known method of preparing voided emulsion polymers is to swell the core of a core-shell emulsion polymer. Each of the claims recites a method of preparing emulsion polymer particles that involves providing an aqueous emulsion including a “swelling agent, under conditions in which there is no substantial polymerization of the monomer.”

The parties disputed the construction of the term swelling agent, and the phrase under conditions in which there is no substantial polymerization of the monomer. Based on an evaluation of the specification and relying on testimony of the Patent Owner’s expert witness, the Board determined that the term swelling agent includes both a structural element, and a functional requirement, that the agent must be capable of permeating the shell and swelling the core of the polymer under the conditions in which it is used.

The Board determined that the challenged claims were not unpatentable under either of the two grounds for which the IPR was instituted: anticipation by Toda (U.S. Patent No. 5,360,827); and obviousness over Touda (U.S. Patent No. 5,077,320). For evaluating each of the grounds, the Board relied on expert testimony provided by each party, and on experimental evidence submitted by the Patent Owner. The Patent Owner demonstrated that Toda did not anticipate, and Touda did not render obvious the challenged claims, by reproducing the example at issue in each reference, and by providing expert testimony to show that each example did not actually contain a swelling agent, because the example did not disclose conditions under which the purported swelling agent would actually function to permeate the shell and swell the core of the polymer, as required by the claims.

This case illustrates the power of using both expert testimony and experimental evidence, where appropriate, to demonstrate whether asserted prior art satisfies the limitations of the challenged claims. Although the Petitioner was able to convince the Board to institute an IPR without using experimental evidence, the Patent Owner was able to show that the challenged claims were not unpatentable, by effectively using both expert testimony and experimental evidence.