In an opinion addressing claim construction, infringement and indefiniteness, the U.S. Court of Appeals for the Federal Circuit affirmed the district court’s findings that the asserted claims were not indefinite and not infringed. Akzo Nobel Coatings, Inc. v. Dow Chem. Co., Case Nos. 15-1331; -1389 (Fed. Cir., Jan. 29, 2016) (Lourie, J.).

Akzo owns a patent covering a method of producing low viscosity aqueous polymer dispersions. The claimed invention prevents the aqueous medium from boiling by maintaining a pressurized extruder and includes a “pressurized collection vessel” that the aqueous dispersion enters. Dow’s accused process uses a pressurized extruder but, rather than entering a pressurized container, the aqueous dispersion passes through a valve, travels through a series of heat exchangers and then collects in an unpressurized compartment.

Dow moved for early summary judgment based on Akzo’s failure to identify a “pressurized collection vessel.” The district court combined the summary judgment and Markman hearings, and construed the term “pressurized collection vessel” to require that some amount of material accumulate in the vessel. Based on this construction, the district court granted summary judgment in Dow’s favor. Akzo appealed.

On appeal Akzo challenged the district court’s narrow construction, arguing that accumulation was not required because the ordinary meaning of “collection” is gather or receive. The Federal Circuit disagreed, noting that such a broad construction would render the word “collection” superfluous. The specification also supported the district court’s construction: Each time “collection” was used, it referred to material accumulated in the vessel. For these reasons, the Federal Circuit affirmed the district court’s claim construction, finding that the term “collection” requires some accumulation of material.

In its cross-appeal, Dow argued that certain asserted claims were indefinite because they included measuring viscosity, but did not specify the temperature at which the viscosity should be measured. The district court previously found that one of skill in the art would know with reasonable certainty that the viscosity is to be measured at room temperature. The Federal Circuit affirmed the district court, noting that it relied on extrinsic evidence without clear error, and the extrinsic evidence did not conflict with the intrinsic evidence.

Dow also argued that the claims were indefinite because one limitation, requiring an elevated temperature, did not specify which steps were to be performed at the elevated temperature. The district court previously found that one of skill in the art would understand which specific steps should be performed at the elevated temperature. The Federal Circuit again affirmed, relying on the disclosure in the specification for support. The Federal Circuit also noted that Dow failed to provide evidence showing that one of skill in the art would notknow with reasonable certainty which steps were to be performed at the elevated temperature.