It's quite literally a sticking point. Labels, seals and coatings can stop paper and cardboard from being recycled – because non-recyclable adhesives, or 'stickies' as they are known in the industry, damage machinery, lower the quality of recycled pulp, or cause entire batches to be rejected, according to scientists at NC State University.
This matters because paper is one of Europe's most recycled materials: around 74% of paper and board consumed in 2024 was recycled. But European authorities are spurring firms to do better. In August, a new Europe-wide packaging and packaging waste regulation (PPWR) kicks in, ordering that all packaging be at least 70% recyclable by 2030, rising to 80% from 2038. German law will also require stricter reporting and licensing fees.
“New laser and ultrasonic sealing tech aims to replace adhesives in paper packaging, boosting recyclability.”
One solution has been water-soluble adhesives. But what if you could skip the adhesive altogether? That's the idea from three German firms – Fraunhofer, Hermann Ultraschall, and Henkel – all based in the country's 'Packaging Valley', a hub for the industry.
In 2023, 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 closes, Fraunhofer hopes to find an industry partner to take it to market. Researchers exhibited at the Interpack trade show in Dusseldorf in May and are hopeful the interest will bear fruit.
"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," says group leader Fabian Kayatz. "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. "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," says head of business Michael Baumann.
Both technologies aim to satisfy ever-tightening regulation and rising fines – and could finally unpick the sticky problem that has long plagued paper recycling.