HS Hyosung Advanced Materials Corp v. Kolon Industries Inc

1. Case Identification

• Case #: IPR2025-00662
• Patent #: 9,789,731
• Filed: February 28, 2025
• Petitioner(s): HS Hyosung Advanced Materials Corp.
• Patent Owner(s): Kolon Industries, Inc.
• Challenged Claims: 1-7

2. Patent Overview

• Title: Hybrid Fiber Cord for Tire Reinforcement
• Brief Description: The ’731 patent discloses a hybrid fiber cord for reinforcing tires, comprising a nylon primarily-twisted yarn and an aramid primarily-twisted yarn. The patent asserts that making the primary twist number of each yarn identical to each other and to the secondary twist number results in a cord with more uniform physical properties, improved strength, and better fatigue resistance compared to conventional cords.

3. Grounds for Unpatentability

Ground 1: Obviousness over Tamura and Structural References

• Claims 1, 2, 4, and 6-7 are obvious over Tamura in view of Baldwin or Baek.
  • Prior Art Relied Upon: Tamura (Japanese Patent No. 2009-68549), Baldwin (Application # 2009/0090447), and Baek (Korean Patent Disclosure No. 10-0245520).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Tamura, which relates to composite fiber cords for rubber hoses, discloses nearly all limitations of independent claims 1 and 4. Tamura taught a hybrid cord of nylon and aramid fibers, wherein each fiber is primarily twisted and then secondarily twisted together. Tamura’s embodiments disclosed primary and secondary twist numbers within the claimed range of 300-500 TPM and that the twist numbers are identical. Tamura also disclosed coating the cord with an adhesive and achieving the claimed strength retention and dry heat shrinkage values. Petitioner asserted that the final limitation of "identical structures" is met by combining Tamura with Baldwin or Baek, whose figures depict nylon and aramid yarns with visually identical structures in a hybrid cord.
    • Motivation to Combine: A POSITA would combine Tamura with the teachings of Baldwin or Baek to achieve a balanced cord. It was well known that using yarns with identical structures and twist numbers produces a balanced cord, which prevents self-twisting, reduces uneven stress distribution, and improves overall tire performance and manufacturing efficiency.
    • Expectation of Success: A POSITA would have an expectation of success because using direct cable corder machines to produce balanced cords with yarns of identical structure was a known and predictable manufacturing technique.

Ground 2: Obviousness over Chung, Harikae, and Yokokura

• Claims 1-4 and 6-7 are obvious over Chung in view of Harikae and further in view of Yokokura.

  • Prior Art Relied Upon: Chung (Korean Patent Disclosure No. 10-2006-0126101), Harikae (Japanese Patent Publication No. 2007-216778), and Yokokura (Application # 2010/0071826).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Chung taught a hybrid tire cord made of nylon and aramid filaments with a twist count in the claimed range of 300-500 TPM. To the extent Chung only suggests the aramid and nylon yarns have the same or similar twist range, Harikae explicitly taught a two-ply hybrid cord where the aramid and nylon fibers have the exact same twist number. To address the strength retention and dry heat shrinkage limitations added during prosecution, Petitioner pointed to Yokokura, which taught testing para-aramid reinforcement cords using the JIS-L 1017 method and disclosed strength retention values (e.g., 89%, 85%, 98%) that fall within the claimed range of 80% or more. Chung disclosed dry heat shrinkage values (2.0-2.5%) that overlap with the claimed 1.5-2.5% range.
    • Motivation to Combine: A POSITA would combine these references to optimize the performance and physical properties of a hybrid tire cord, the same problem addressed by the ’731 patent. A POSITA would modify Chung’s cord to have identical twist numbers as taught by Harikae to improve cord properties and productivity. Further, a POSITA would incorporate the high strength retention rates from Yokokura to enhance durability, a known goal in the art.
    • Expectation of Success: The combination involved applying known principles to achieve predictable results. Modifying twist numbers and optimizing for high strength retention were matters of routine experimentation for a POSITA, who would understand that higher retention ratios lead to better performance.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including:

  • (Ground 2) Adding Barnes (Application # 2009/0124149) to the Tamura combination to explicitly teach measuring breaking tenacity and elongation per the ASTM D885 (2004) standard as required by claim 3.
  • (Grounds 3 & 5) Adding Rowan (Application # 2005/0249949) and/or Buchanan (European Patent Pub. No. 0405887A1) to the primary combinations to teach that the twisting steps of claim 4 could be performed simultaneously and continuously, as required by claim 5, for improved manufacturing efficiency.

4. Key Claim Construction Positions

• Petitioner argued that while no terms required express construction, the term "identical structures" was a key point of dispute. Petitioner contended that the prior art met this limitation under the Patent Owner’s own interpretation from a related district court complaint, where Patent Owner alleged that having identical first, second, and third twist numbers results in "identical structures." Since prior art like Tamura taught this twist configuration, it disclosed the limitation. Alternatively, Petitioner argued that figures in Baldwin and Baek visually depict identical structures, and that Chung’s disclosure of "similar structures" would be understood by a POSITA as effectively identical in the imprecise field of textiles.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that the Board should not exercise discretionary denial under either Fintiv or 35 U.S.C. §325(d).
  • Fintiv (§314(a)): Petitioner contended that the factors weighed against denial because the parallel district court litigation was in its very early stages, with a trial date not set until February 2026, well after the Board’s statutory deadline for a Final Written Decision (FWD).
  • §325(d): Petitioner asserted that the arguments and prior art were not the same or substantially the same as what was before the examiner. The specific combinations, particularly the inclusion of Baek, Barnes, Buchanan, Harikae, Yokokura, and Rowan, were never considered during prosecution. The examiner’s allowance was based on overcoming a rejection based solely on Baldwin, and Petitioner argued that the newly cited art (e.g., Tamura, Yokokura) clearly teaches the limitations that Baldwin allegedly lacked.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-7 of Patent 9,789,731 as unpatentable.