Borealis wins EPO ruling against Mitsui Chemicals, retaining rights to POE solar film after patent claims were declared invalid.
The European Patent Office (EPO) has delivered a decisive ruling in favour of Austrian-based plastics manufacturer Borealis, resolving a high-profile patent dispute with Japanese chemical company Mitsui Chemicals. The legal contention revolved around the manufacturing rights to a polyolefin elastomer (POE) film used in solar cell production—an essential material that serves as an encapsulant, protecting solar cells from degradation due to moisture, temperature variation, and ultraviolet radiation. This encapsulant also functions as an adhesive, maintaining the integrity of the cell layers over time.
Borealis’s POE material, marketed under the brand name Quenty, plays a crucial role in enhancing the efficiency and durability of photovoltaic modules. The product has been part of the company's solar materials portfolio for some time and has gained recognition for its performance and reliability in renewable energy applications.
The dispute was initiated by Mitsui Chemicals, which sought to patent its own POE material, branded Engage 8400. Mitsui claimed intellectual property rights over this version of the encapsulant, alleging it to be a novel development. However, Borealis contested this claim on the grounds that their POE material had already been made publicly available prior to Mitsui’s patent filing.
The central question in the dispute was whether Borealis’s POE could be considered "prior art"—a legal concept used in patent law to establish whether an invention is already known or available before a patent application is filed. Although Mitsui argued that Borealis’s material could not be easily reverse-engineered or reproduced, the EPO determined that the product still met the criteria for prior art. As a result, the patent application submitted by Mitsui Chemicals was deemed invalid due to a lack of novelty.
The outcome ensures that Borealis retains the right to manufacture and market its POE-based Quenty encapsulant without any legal barriers imposed by Mitsui's claims. It also reinforces Borealis’s position as a leader in the innovation of advanced materials for the renewable energy sector.
While Borealis has not issued a public comment on the ruling, the company's strong track record in innovation speaks volumes. In 2024 alone, the firm filed 121 new priority patent applications, contributing to its extensive intellectual property portfolio, which now includes approximately 12,300 patents. This substantial patent activity cements Borealis's status as Austria’s most prolific innovator in the field of plastics and materials science.
The ruling by the EPO not only highlights the importance of establishing clear timelines in patent filings but also underscores the competitive landscape of solar material technologies.
