Siegwerk wins deinking patent

Siegwerk has secured a European patent, EP4107326, for a primer technology that lets printing inks which cannot be deinked under commercially used conditions be removed from plastic substrates during recycling, as the Packaging and Packaging Waste Regulation (PPWR) raises recycled-content requirements.

The patent covers solvent-based and water-based deinking primers, and the Siburg-based company's wider deinking portfolio also includes UV printing applications. At its core is a functional primer between the plastic substrate and the printing layer, which allows the print layer to be released and removed during alkaline washing before the polymer is reprocessed. The concept also covers constructions with ink between additional layers, extending to complex flexible packaging, labels and shrink sleeves.

Under the PPWR, plastic packaging will need minimum shares of post-consumer recycled material from 2030. According to CEFLEX, around 2.5 million metric tons of flexible packaging-derived post-consumer recyclate will be required by 2030 to meet the targets for flexible packaging alone. Siegwerk says effective ink removal can improve recyclate quality by reducing discoloration, odor and contamination. For flexibles, printing inks often cover larger surface areas or sit within laminated structures, while adhesives, barrier layers and multilayer constructions complicate sorting, washing and recycling.

Siegwerk has validated the technology across different substrates, ink technologies and packaging constructions in its internal deinking laboratory and in collaborative research and industry projects. One example is a deinkable mono-material flexible pouch concept, which Siegwerk and partners showed could achieve effective print removal while keeping the structure recyclable, and which won the German Packaging Award in Gold.

'We recognized early that removing printing inks can contribute to improving the quality of recycled plastics. This becomes even more relevant as the value chain needs to deliver significantly more recycled material at the quality required for its next application. Especially for flexible packaging, there will not be one answer for every structure and recycling stream. Our early investment in deinking technologies and the expertise we have built put us in a strong position to support the industry wherever ink removal becomes an important lever for recyclate quality,' said Lara Kleines, recycling and polymer expert at Siegwerk.

The European patent complements US Patent US12291051B2, granted in May 2025.