It is a sticking point that has plagued the recycling industry for years: the humble label or seal that renders otherwise recyclable paper and cardboard useless. Non-recyclable adhesives, known as "stickies" in the trade, can damage machinery, lower the quality of recycled pulp, or cause entire batches to be rejected, according to scientists at NC State University.
That is a costly problem. Paper is one of Europe's most recycled materials: around 74% of paper and board consumed in 2024 was recycled. But with new EU regulations looming, the pressure is on to do better. From August, the European packaging and packaging waste regulation (PPWR) will require all packaging to be at least 70% recyclable by 2030, rising to 80% from 2038. German law will also impose stricter reporting and licensing fees.
“German firms develop laser and ultrasonic sealing to replace adhesives that hinder paper recycling, aiming to meet EU targets.”
Now three German firms – Fraunhofer, Hermann Ultraschall, and Henkel – are proposing a radical solution: skip the adhesive entirely. It is no coincidence they are all based in Germany, home to the so-called Packaging Valley, a hub for the packaging industry. Their efforts are partly driven by tightening commercial recycling rules and rising fines for non-compliance.
In 2023, German research organisation Fraunhofer launched the PAPURE project to develop a laser-based heating process that seals paper packaging without any adhesive. From September, when the project is set to officially close, Fraunhofer hopes to find an industry partner to bring the technology to market. Researchers exhibited their work at the Interpack trade show in Dusseldorf in May and are optimistic about the interest they attracted.
"There are not really many paper sealing technologies without any foreign materials, so it's a great technology and we feel it's likely that we can bring it to market," said Fabian Kayatz, Fraunhofer researcher group leader. "If we are optimistic, we will have the first solution out in two years."
Also in 2023, engineering firm Hermann Ultraschall bought the rights to develop a patented ultrasonic paper sealing technology, a process it likens to welding. Michael Baumann, the company's head of business development, said: "We are really actively at the moment in discussion with several really big players in the market with the focus of bringing this technology into mass production."
Meanwhile, a simpler alternative already exists: water-soluble adhesives. But the laser and ultrasonic methods promise to eliminate adhesives entirely, potentially revolutionising paper recycling. Whether these innovations can scale up in time to meet the EU's 2030 target remains to be seen.