In Rockwool Int’l A/S v. Knauf Insulation, Inc., PGR2022-00022, Paper 10 (P.T.A.B. July 6, 2022), the PTAB denied institution because the challenged patent, U.S. 10,968,629 (“the ’629 patent”), was not eligible for post-grant review (“PGR”).


Knauf’s ’629 patent is directed to a method of manufacturing formaldehyde-free insulating board having characteristics comparable to boards containing formaldehyde. Id. at *2. The ’629 patent was filed after March 16, 2013, when certain provisions of the America Invents Act (“AIA”) went into effect but claims the benefit of an application filed before March 16, 2013. The ’629 patent, therefore, issued from a “transition application,” as defined in AIA SEC. 3(n)(1). Thus, whether the patent is subject to the provisions of the AIA and, therefore, eligible for PGR, turns on the effective filing dates of claims introduced during prosecution and those issued in the patent. If the application ever contained a claim with an effective filing date after March 16, 2013, then the patent is eligible for PGR. Otherwise, it is not subject to the AIA or any PGR proceedings.

Rockwool challenged the ’629 patent on two grounds: anticipation and lack of written description. However, Rockwool first had to establish that the ’629 patent was in fact eligible for PGR. Id. at *3. Specifically, Rockwell had to establish that the ’629 patent issued from an application described in AIA section 3(n)(1):

[T]he amendments made by this section shall take effect upon [March 16, 2013], and shall apply to any application for patent, and to any patent issuing thereon, that contains or contained at any time

(A) a claim to a claimed invention that has an effective filing date as defined in section 100(i) of title 35, United States Code, that is on or after [March 16, 2013]; or

(B) a specific reference under section 120, 121, or 365(c) of title 35, United States Code, to any patent or application that contains or contained at any time such a claim.

AIA § 3(n)(1) (emphasis added).

Rockwool asserted two bases for its argument that the ’629 patent was eligible for PGR. First, Rockwool contended that certain claims introduced at one point during prosecution, but not issued in the ’629 patent, recited a Solids Content Limitation that had no written description support in the pre-March 16, 2013 priority application. Id. at *6. Second, Rockwool argued that certain claims of the ’629 patent contained Dry Weight and Physical Property Limitations that likewise had no written description support in the priority application. Id.

Solids Content Limitation:

During prosecution of the ’629 patent, applicant submitted amended claims that recited “a solids content of less than about 26.5% by weight.” The Examiner rejected the amended claims under §112(a), finding that the original disclosure lacked written description support for the Solids Content Limitation. Id. at *6. Applicant removed the limitation, and it was not recited in the issued claims of the ’629 patent. Id. at *7.

Rockwool’s PGR-eligibility argument was based on the phrase “contained at any time” in AIA 3(n)(1). However, the PTAB agreed with Knauf that, in this case, the temporary presence of the Solids Content Limitation did not trigger the AIA. Id. at *7. According to the PTAB, as explained in the MPEP § 2159.02, “submitting amended claims directed to new matter does not convert a pre-AIA application to an AIA application” because the application cannot “contain” a claim directed to prohibited new matter. Id. at *7-8. The PTAB also found support for its decision in Intex Recreation Corp. v. Team Worldwide Corp., PGR2019-00015, Paper 7 at 12–14 (P.T.A.B. May 14, 2019).

Dry Weight and Physical Property Limitations:

Claim 1 of the ’629 patent recites percentage ranges for components of the binder solution: about 73% to about 96% of a reducing sugar reactant and about 4% to about 27% of an amine reactant. Id. at *9. Claim 1 further recites four physical properties of the mineral fiber insulating board: density, ordinary compression strength, weathered compression strength, and change in thickness. Id. at *10.

Rockwool argued that “the ’629 Patent claims lack written description support for these limitations because the specification does not describe how the entire claimed range of sugar and amine reactants possesses the required functional properties.” Id. Knauf countered that the recited structural features of the claims give the binder solution its functional properties. Id. at *11.

A slightly different analysis was required for the Dry Weight and Physical Property Limitations because they were present in the issued claims. The PTAB acknowledged Federal Circuit precedent setting out what is required for sufficient written description support of a “functionally-defined” genus claim:

[T]he disclosure of either [1] a representative number of species falling within the scope of the genus or [2] structural features common to the members of the genus so that one of skill in the art can ‘visualize or recognize’ the members of the genus.

Id. at *12.

The PTAB went on to explain that Rockwool “fail[ed] to establish that the claims of the ’629 patent recite a ‘functionally-defined genus’” triggering application of the Federal Circuit’s test. Id. at *13. Instead, the PTAB determined that the Dry Weight and Physical Property Limitations at issue are structural features, not functional, concluding that claim 1 does not describe a binder solution by what it does but rather by its structural components. Id. at *13-14. The priority application provided written description support for the Dry Weight Limitations and the Physical Property Limitations, including the recited ranges. Id. at *14-15. Since the claims were entitled to the priority application’s filing date, Knauf’s patent was not eligible for PGR and Rockwool’s Petition was denied on that basis.

Take Aways

The eligibility of a patent for PGR is a threshold issue. Lack of PGR-eligibility is the basis for about 19% of all PGR denials.[1] This case serves as a reminder that, according to the MPEP and PTAB, a patent applicant cannot accidentally convert a pre-AIA application into an AIA application by inadvertently introducing new matter into the claims.

Successful written description challenges can trigger PGR eligibility. Issued claims found to lack support in pre-AIA priority applications may be found PGR-eligible. See, e.g., Grünenthal GmbH v. Antecip Bioventures II LLC, PGR2017-00008, Paper 7 (P.T.A.B. July 7, 2017). In US Endodontics, LLC v. Gold Standard Instruments, LLC, PGR2015-00019, the patent was PGR-eligible because the Board agreed with Petitioner that neither the challenged patent nor the priority applications contained an enabling disclosure. Therefore, the effective filing date of the challenged patent claims was the actual post-AIA filing date, and the patent was subject to AIA §3(n)(1) and was PGR-eligible.

As shown in Rockwool, the initial burden is on Petitioner to establish in the Petition that the challenged patent is subject to PGR. See 35 U.S.C. § 326(e); 37 C.F.R. § 42.20(c); 37 C.F.R. § 42.204(a); Inguran, LLC v. Premium Genetics (UK) Ltd., PGR2015-00017, Paper 8 (P.T.A.B. Dec. 22, 2015); US Endodontics, LLC v. Gold Standard Instruments, LLC, PGR2015-00019, Paper 17 (P.T.A.B. Jan. 29, 2016).

When faced with a PGR-eligibility argument, Patent Owner then has a burden of production to show in the Patent Owner Preliminary Response how the challenged claims are supported in a pre-AIA application and are not PGR-eligible. But the burden of persuasion remains on the Petitioner. See, e.g., Mylan Pharms. Inc. v. Yeda Research & Development Co. Ltd., 2016-00010, Paper 9 (P.T.A.B. Aug. 16, 2016).

The entitlement to priority of challenged claims or the relevant date of an asserted reference may also arise In IPRs, bringing in §112 arguments even though IPR grounds are limited to patents and printed publications. See, e.g., ButamaxTM Advanced Biofuels LLC v. Gevo, Inc., IPR2013-00539 (Petitioner successfully challenged priority claim and reference was prior art to the challenged patent); Baxter Healthcare Corp. v. Millenium Biologix, LLC, IPR2013-00591 and IPR2013-00583 (Patent Owner successfully fended off priority date challenge and references were not prior art to the challenged patent).

It is always a good prosecution practice habit to keep the §112 chain of priority tight.