IR Shielding Technology at the Heart of a Multiyear Legal Battle
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| (Source: Sumitomo Chemical, https://www.sumitomo-chem.co.jp/english/) |
Korean materials manufacturer Sangbo and Japan's Sumitomo Chemical are approaching the end of a long-running patent invalidity dispute involving advanced infrared shielding technology.
The patent at the center of the battle is titled "Infrared Shielding Material Particle Dispersion, Infrared Shielding Body, and Method for Producing Infrared Shielding Material Particles, and Infrared Shielding Material Particles" (Patent No. KR0701735).
The disputed technology relates to the development of a transparent infrared shielding material that effectively blocks infrared (IR) light while allowing visible light to pass through. The key innovation lies in the use of tungsten oxide (WO₃) and composite tungsten oxide particles, which enhance IR shielding performance. Crucially, this process does not require high-temperature treatment or complex equipment, making it more efficient and scalable. The shielding materials are created by dispersing tungsten oxide particles in a medium to manufacture IR-blocking films. These films are designed to maintain transparency and selectively absorb IR radiation without darkening or changing the color of the material.
In July 2020, Sangbo initiated a validity challenge against Sumitomo's patent, filing a patent invalidation trial with the Korean Intellectual Property Trial and Appeal Board (KIPTAB). By 2021, KIPTAB ruled in favor of Sangbo, finding key claims—specifically Claims 1, 6, 9 through 13, and 18—invalid.
Sumitomo filed an appeal in the Korean Patent Court to reverse the invalidation decision. The final hearing in the Patent Court took place in August 2024, and a ruling is expected in November 2024, marking a critical point in the prolonged dispute.
In a parallel development, Sumitomo responded to the patent challenge by requesting a correction trial in October 2021, seeking to amend the patent to overcome the invalidation ruling. KIPTAB granted this amendment request in April 2022.
In May 2022, Sangbo once again took legal action by filing a correction invalidation trial, aiming to invalidate the approved amendment. However, in December 2023, KIPTAB dismissed Sangbo's correction invalidation petition.
Sangbo escalated the matter by filing a separate appeal with the Patent Court in January 2024, challenging KIPTAB's decision to dismiss their correction invalidation trial. Despite their efforts, Sangbo lost this appeal in June 2024 but has since escalated the case to a higher court by filing an appeal in July 2024.
The dispute between Sangbo and Sumitomo began in April 2020, when Sumitomo filed a patent infringement lawsuit against Sangbo in the Seoul Central District Court. In response, Sangbo launched a patent invalidation trial, while Sumitomo sought to amend the patent through a correction trial. As a result, the patent infringement lawsuit is currently on hold, pending the resolution of the invalidation proceedings. Once the validity-related disputes are resolved, it is expected that the infringement lawsuit will resume, potentially leading to further legal battles between the two companies.
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| (Source: Sang, https://dart.fss.or.kr/dsaf001/main.do?rcpNo=20240813001029) |
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