Patent No. EP3819426 (titled "Compostable Cellulose-Based Paper For Gas Barrier In Packaging Material") was filed by Ahlstrom Munksj OYJ on Nov 7, 2019. The application was issued on Mar 29, 2023.

Patent oppositions filed by competitors challenge the validity of a granted patent. These oppositions are typically based on claims of prior art, lack of novelty, or non-obviousness. They are a key part of the process for determining a patent's strength and enforceability.
| Company | Opposition Date | Representative |
|---|---|---|
| UPM KYMMENE OYJ | Dec 29, 2023 | COHAUSZ & FLORACK |
The dossier documents provide a comprehensive record of the patent's prosecution history - including filings, correspondence, and decisions made by patent offices - and are crucial for understanding the patent's legal journey and any challenges it may have faced during examination.
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