PTAB

IPR2018-01110

Baldwin Filters, Inc. v. Donaldson Company, Inc.

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1. Case Identification

2. Patent Overview

  • Title: Method of Manufacturing an Air Filter Cartridge
  • Brief Description: The ’700 patent discloses methods for manufacturing fluid filter cartridges, particularly air filters with a straight-through or axial flow configuration. The invention centers on a filter media pack that is circumscribed by a cured-in-place resin coating and is provided with a separate, molded housing seal.

3. Grounds for Unpatentability

Ground 1: Obviousness of Claim 34 over Wydeven427 and Holzmann

  • Prior Art Relied Upon: Wydeven427 (Patent 4,410,427) and Holzmann (Patent 6,568,540).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Wydeven427 discloses a method of manufacturing an air filter cartridge with nearly all of claim 34's limitations, including a fluted media pack and applying a curable resin (a sealant material like urethane or hot melt caulk) that circumscribes the media pack. Petitioner asserted that Wydeven427 fails to teach that the housing seal is "molded" and provided "around the media pack." Holzmann was introduced to supply these missing elements, as it explicitly teaches providing a seal by molding it around the filter media pack to create an integral gasket.
    • Motivation to Combine: A POSITA would combine Wydeven427 with Holzmann's teaching of a molded seal because it was a conventional and well-known method for providing a housing seal on air filter cartridges. Holzmann shows this method improves sealing integrity and reduces the required housing closing force, providing a clear reason to modify the filter of the ’427 patent.
    • Expectation of Success: A POSITA would have expected success in combining these known features, as it involved substituting one known type of seal for another to achieve the predictable improvements taught by Holzmann.

Ground 2: Obviousness of Claims 34 and 38 over Wydeven427, Holzmann, and Millington

  • Prior Art Relied Upon: Wydeven427 (Patent 4,410,427), Holzmann (Patent 6,568,540), and Millington (Patent 3,133,847).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the combination of Wydeven427 and Holzmann for claim 34. To meet the additional limitation of claim 38, which requires that the step of "applying a curable resin comprises spraying the curable resin," Petitioner introduced Millington. Millington was asserted to teach forming an impervious outer coating on a filter element by spray coating an adhesive resin.
    • Motivation to Combine: A POSITA would be motivated to apply the curable resin of the Wydeven427/Holzmann combination using the spraying technique from Millington. Millington teaches that spraying is a conventional method that reduces cost, increases production speed, and involves less manual operation, providing strong economic and manufacturing incentives for its adoption.
    • Expectation of Success: Given that spraying was a known technique for applying resins to filters, a POSITA would have reasonably expected to successfully apply the resin of Wydeven427 via spraying without undue experimentation.

Ground 4: Obviousness of Claim 34 over Gillingham247 and Wydeven247

  • Prior Art Relied Upon: Gillingham247 (Patent 5,792,247) and Wydeven247 (Application # 2002/0096247).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner presented an alternative combination starting with Gillingham247, which was argued to disclose a method of manufacturing an air filter with a fluted media pack and a molded housing seal integrally formed around the pack. Gillingham247 allegedly does not disclose the claimed steps of applying and curing a resin to form a cured-in-place coating. Wydeven247 was cited to teach these missing steps, as it discloses injecting a curable resin into a mold to form a protective shell directly on the outer circumference of a filter media.
    • Motivation to Combine: A POSITA would be motivated to modify the Gillingham247 filter by incorporating the resin coating taught by Wydeven247. The motivation was to add a protective layer to the filter media pack, a known benefit taught by Wydeven247. Petitioner also argued it was well-known to apply such a protective coating and then provide the housing seal on that layer.
    • Expectation of Success: The combination involved applying a known protective coating method to a known filter structure, which would have been a straightforward modification with a predictable outcome for a POSITA.

  • Additional Grounds: Petitioner asserted numerous additional obviousness challenges against claims 34 and 38. These grounds relied on similar rationales but substituted other references, such as Parmele (Patent 3,039,908) to teach spraying the resin; Ishii (JP60-155921) or Krisko (’534 application) as alternative base references for filter structures with molded seals; and Engel (Patent 4,720,292) to teach the benefits of soft, molded seals.

4. Key Claim Construction Positions

  • "molded": Petitioner argued this term means "formed using a mold," pointing to the patent's own text which clarifies that this can include both "molded in place" and "separately molded" and then attached. This construction was critical to establishing that prior art references teaching seals formed by molding (like Holzmann) met the claim limitation.
  • "spraying": For claim 38, Petitioner defined "spraying" as "applying in the form of tiny drops." This construction was used to argue that references like Millington and Parmele, which disclose spray coating adhesives or resins onto filter media, directly teach the method recited in dependent claim 38.
  • "separate": Petitioner contended that the step of providing the housing seal being "separate" from applying the resin is met when the two processes are distinct fabrication steps. This was used to argue that combining a reference teaching molding a seal with a different reference teaching spraying a resin inherently results in separate steps, thus satisfying the claim.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 34 and 38 of Patent RE46700 as unpatentable under 35 U.S.C. §103.