In CQV Co., Ltd. V. Merck Patent GmbH, PGR2021-00054, Paper 56 (P.T.A.B. Aug. 11, 2022), the Patent Trial and Appeal Board (“the PTAB”) found that Petitioner did not show that the challenged claims of U.S. Patent No. 10,647,861 (“the ’861 patent”), were unpatentable.


The ’861 patent relates to alumina flakes, compositions containing them, and a process for making them. Independent claims 1 and 18 read:

1. Al2O3 flakes having a particle thickness of 130-400 nm, a D50-value of 15-30 μm, a D90-value of 30-45 μm, a D10-value of <9.5 μm and wherein the flakes are α-alumina flakes.

18. Al2O3 flakes having a particle thickness of 130-400 nm, a D50-value of 15-30 μm, a D90-value of 30-45 μm, a D10-value of <9.5 μm, which are doped with TiO2, ZrO2, SiO2, SnO2, In2O3, or ZnO or a combination thereof and wherein the flakes are α-alumina flakes.

Petitioner alleged that the ’861 patent claims were unpatentable as obvious on four grounds. Two of these grounds were based upon, inter alia, the Xirallic product. Id. at *6-7. According to Petitioner, Xirallic was in public use prior to the effective filing date of the ’861 patent, April 30, 2013, as evidenced by “US Patent No. 6,641,874, issued in 2003, [which] refers to ‘Xirallic’ as a commercially available pigment from Merck KGaA.” Id. at *7. Petitioner further argued that the specification of the ’861 patent admitted “[p]earlescent pigments based on α-Al2O3 flakes are well-known in the literature and commercially available under the trademark XIRALLIC from Merck KGaA.” Id. at *16. Petitioner relied on other secondary references to provide the properties recited in the claim limitations.

Patent Owner disputed that Petitioner’s sampled Xirallic products were prior art, arguing that Petitioner “fails to distinguish between the Xirallic® product line, particular Xirallic® products within the product line, and the specific lots of product that Petitioner tested.” Id. at *20. According to Patent Owner, none of the references relied upon to show public availability “specifically refer to the particular products or lots tested by Petitioner’s experts.” Id. Patent Owner further argued that the Xirallic products tested by Petitioner’s experts are Patent Owner’s own products, and therefore qualify for the 35 U.S.C. § 102(b)(1)(A) exception. Id.

Petitioner replied that Patent Owner failed to show the 35 U.S.C. § 102(b)(1)(A) exception applies. Id. at *23. In addition, Petitioner argued that Xirallic Samples B and C were manufactured in 2007 and commercially available before Patent Owner’s April 30, 2012, critical date. Id. According to Petitioner, “[expert] testimony that the product was purchased in October 2011 provide[d] unrebutted evidence establishing that sample lot was publicly available prior to the critical date, whether it be April of 2012 or 2013.” Id.


The PTAB concluded that Petitioner had not sufficiently shown that the Xirallic samples tested and relied upon were prior art. Id. at *25. Petitioner did not establish persuasively “that the samples, collectively represented here by Sample C, were ‘in public use, on sale, or otherwise available to the public’ before either the undisputed effective filing date of April 30, 2013, which Petitioner alleges to be the critical date, or April 30, 2012, alleged by Patent Owner to be the critical date under the Section 102(b)(1)(A) exception.” Id.

The problem was that Petitioner’s assertion that Xirallic was publicly available and well-known based on several references was not tied to the Xirallic pigment line tested as Sample C. Id. at *26. Petitioner’s argument specific to Sample C was only supported by vague, uncorroborated expert testimony. Id. at *27-28. “Without corroboration, we find that there is an insufficient basis to rely on Mr. Choi’s testimony regarding the approximate time frame that Petitioner allegedly purchased the lot for Sample C.” Id. at *28.

The PTAB, therefore, analyzed the asserted grounds without reference to the Xirallic product. Id. at *30. It found that Petitioner did not adequately show how the combined teachings of the other asserted references would lead one of ordinary skill in the art to the claimed invention. Id. at *30-31.


Parties relying on expert testimony may need to spend time building up the supporting evidence to corroborate the expert testimony. Physical records such as letters, invoices, patent applications, and articles can provide corroboration to testimony, if sufficiently verified. Lessons from cases discussing the types of proof required for showing inventorship may be helpful in this regard.

And the evidence relating to a specific sample tested and relied on needs to tie to the asserted reference/argument. In this case, it was fatal to Petitioner’s case that the data from testing Sample C was not sufficiently tied to Petitioner’s argument about the Xirallic product alleged to be in prior use.