Daikin Industries Ltd v. Chemours Co FC LLC

1. Case Identification

• Case #: IPR2018-00992
• Patent #: 7,122,609
• Filed: April 30, 2018
• Petitioner(s): Daikin Industries, Ltd. and Daikin America, Inc.
• Patent Owner(s): The Chemours Company FC, LLC
• Challenged Claims: 1-7

2. Patent Overview

• Title: High Melt Flow Fluoropolymer
• Brief Description: The ’609 patent discloses a partially-crystalline fluoropolymer for insulating cables, comprising tetrafluoroethylene (TFE) and hexafluoropropylene (HFP). The claimed copolymer is defined by four key properties: a specific composition corresponding to a hexafluoropropylene index (HFPI), production in the absence of added alkali metal salt, a high melt flow rate (MFR), and a low number of unstable endgroups.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1-7 by Hiraga

• Prior Art Relied Upon: Hiraga (Japanese Application Publication No. 2002-249585).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Hiraga, which describes a method for removing unstable endgroups from FEP-copolymers, inherently discloses a copolymer that meets every limitation of the challenged claims. Specifically, Petitioner pointed to Hiraga’s "Comparative Example 1," which after processing resulted in a copolymer with a final MFR of 30.0 g/10 min, 0 unstable endgroups, and a calculated HFPI of 5.2. These values fell squarely within the ranges claimed in the ’609 patent. Petitioner contended that Hiraga’s silence regarding the use of alkali metal salts during the polymerization and isolation steps satisfied the claim’s negative limitation, as Hiraga used a non-alkali-metal initiator (ammonium persulfate). The dependent claims were also allegedly anticipated, as Hiraga’s copolymer contained perfluoro(propyl vinyl ether) (PPVE) in an amount meeting the limitations of claims 3 and 4.

Ground 2: Anticipation and Obviousness of Claims 1-7 over Kono

• Prior Art Relied Upon: Kono (Patent 6,743,508).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that Kono teaches FEP-copolymers for high-speed wire extrusion that anticipate or render obvious the challenged claims. Kono’s "Comparative Example 3" was argued to anticipate most claims, disclosing a copolymer with an HFPI of 4.1, an MFR of 28.3 g/10 min (within the range of "about 30±3"), exactly 50 unstable endgroups, and produced without alkali metal salts. Kono's "Example 2" was also cited, having 58 unstable endgroups, which Petitioner argued meets the limitation of "about 50." For limitations not expressly met, Petitioner argued for obviousness.
  • Motivation to Combine (for obviousness): Kono taught that FEP-copolymers for high-speed extrusion should have an MFR of 30 g/10 min or more. Petitioner argued that for any of Kono's examples with MFR values slightly outside the claimed range (e.g., Comparative Example 5 with an MFR of 35.1 g/10 min), a POSITA would have been motivated by Kono’s own teachings to optimize reaction conditions to achieve an MFR within the claimed range. This was presented as routine experimentation to find an optimal range based on the general conditions disclosed in the prior art, with a high expectation of success.

Ground 3: Obviousness of Claims 1-7 over Kaulbach

• Prior Art Relied Upon: Kaulbach (Patent 6,541,588).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner contended that Kaulbach's "Sample A11" renders the claims obvious. Kaulbach taught FEP-copolymers with improved processability, emphasizing the importance of eliminating unstable endgroups (preferably to less than 40) and avoiding metal contamination by using an alkali-metal-salt-free recipe. Sample A11 had an HFPI of 4.1 and only 28 unstable endgroups, and was polymerized without alkali metal salt, meeting several key limitations. However, its disclosed MFR was 24 g/10 min, which is outside the claimed range of 30±3 g/10 min.
  • Motivation to Combine (to modify): A POSITA would have been motivated to modify Sample A11 to increase its MFR to fall within the claimed range. Kaulbach’s stated purpose was to provide a material for high-speed processing, and it was well known in the art that a higher MFR allows for faster extrusion speeds. Petitioner argued that increasing the MFR of Kaulbach’s copolymer to achieve the known benefit of higher processing speed was a predictable optimization, not an inventive step.
  • Expectation of Success: Because methods for adjusting MFR were well-known, a POSITA would have had a reasonable expectation of success in modifying Kaulbach's process to produce a copolymer with the claimed MFR while retaining its other desirable properties.

• Additional Grounds: Petitioner asserted an additional obviousness challenge based on combining Hiraga with Kaulbach, arguing a POSITA would combine Kaulbach’s teaching of avoiding alkali metals with Hiraga’s process to achieve a fully alkali-metal-free copolymer.

4. Key Claim Construction Positions

• "polymerized and isolated": Petitioner argued this term should be construed to mean "polymerizing monomers and removing a resulting copolymer from a polymer dispersion." Critically, this construction was argued to exclude subsequent, separate steps like endgroup stabilization. This interpretation was central to Petitioner's argument that references like Hiraga, which may have used an alkali metal during a separate stabilization step, still satisfied the negative claim limitation because the polymerization and isolation steps themselves were alkali-metal-free.
• "about 30±3 g/10 min": Petitioner proposed a narrow construction of "greater than 26 g/10 min and less than 34 g/10 min." This construction was based on examples in the ’609 patent’s specification which characterized copolymers with MFRs of 26 and 35 g/10 min as having "unacceptable" and "inadequate quality," respectively, thereby defining the outer bounds of the claimed range.
• "about 50 unstable endgroups": Petitioner argued this should be construed as "approximately 50 unstable endgroups," consistent with the ordinary meaning of "about." This construction would allow values slightly greater than 50, such as the 58 endgroups disclosed in Kono's Example 2, to fall within the literal scope of the claim.

5. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-7 of the ’609 patent as unpatentable.