Herma: Label adhesives for better cardboard recycling

Provided the recycling processes are right, logistics cartons and folding boxes can be recycled not only 4 to 7 times, as previously assumed, but up to 25 times. This is the result of a study conducted at the University of Graz in 2021. In order to optimise the recycling of cardboard and paper, HERMA has therefore developed a new range of pressure-sensitive adhesives and corresponding pressure-sensitive laminates. These are characterised by the fact that logistics and other labels produced from them cause practically no adhesive contamination in the recycling process. HERMA has already received certification from the Papiertechnische Stiftung (PTS) for five pressure-sensitive laminates, i.e. for label materials including pressure-sensitive adhesives. The only condition that such an adhesive laminate must fulfil according to the PTS certificates: It must not account for more than 25 per cent of the mass of the cardboard. "In view of the low weight of a label compared to the cardboard used, however, this condition is probably always fulfilled," says Dr Stefan Kissling, Development Manager Adhesives and Special Coatings at HERMA Haftmaterial. "It was important for us to have not only the pressure-sensitive adhesives certified, but also the complete laminates. Because that corresponds to the application in practice. To our knowledge, HERMA is currently the only company in the industry to offer such certified laminates." For three of the four new adhesives, the use of multi-layer technology was a key to success; HERMA is the pioneer of this technology.

Four new adhesives for five new laminates
The new 72Bpt adhesive is used in combination with two lightly coated paper materials, HERMAweiß super (grade 240) and HERMAextracoat (grade 242). Both laminates are characterised by their good initial adhesion and are therefore ideally suited for carton labelling. For laser sheet applications, which are particularly common in logistics labelling, HERMA has developed a composite of the new 72Apc pressure-sensitive adhesive and HERMAlaser sheet (grade 135). In the area of thermal labels, HERMA now offers an option for optimised cardboard and paper recycling that has also been certified by PTS: an adhesive composite consisting of the new 72Eps adhesive and HERMAtherm nature (grade 900), the first thermal label adhesive material without chemical developers. The 72Eps also shows good adhesion even at low temperatures and is also suitable for very fast-running labelling systems. The fifth PTS-certified laminate is a very universally applicable labelstock consisting of the new, single-layer pressure-sensitive adhesive 72C and the labelstock HERMAweiß (grade 601). Its satin surface not only achieves very good print quality in conventional printing processes. It is also very well suited for laser printers and good for thermal transfer printing. "With the five new PTS-certified laminates, we cover almost all applications that occur in carton and folding carton labelling," says Dr Stefan Kissling. "This means that label printers and users can always find a suitable solution to further improve carton recycling and thus the important material cycle."