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From bottle to bottle

Self-adhesive technology provider Herma is about to unveil a new wash-off adhesive for label applications

Herma is preparing to launch a pioneering new wash-off adhesive for labels that allows recycling operators to produce high-purity PET pellets completely free of negative residues – no remains of paper or film labels, and no residual adhesive. The innovation means containers and bottles made of PET can be recycled more or less infinitely. Even when used with film labels, the adhesive achieves a 100 per cent wash-off score. In other words, all contaminants, such as printing inks and residual adhesive, are removed together with the label.

Unlike downcycling or cascading, the resulting continuous cycle ranks among the most important requirements of a sustainable economy. The focus has long since been not only on PET beverage bottles, but also on detergent bottles, soap dispensers and cans for food and cosmetics. HERMA’s new adhesive, named 62Rpw, offers both reliable adhesion and good resistance to the effects of moisture. Regular industrial cleaning processes are capable of removing it without trace. HERMA has been able to achieve this previously elusive combination thanks to innovative multi-layer technology: the intermediate layer enables the adhesive to bond securely with the label and therefore allows it to be removed completely from the PET surface later. 62Rpw will initially be available with a wet-strength and alkali-proof paper and a PP film: For HERMA coat greaseproof (grade 228) and HERMA PO transparent (grade 846) label materials, recyclability certificates have already been secured from the Institute cyclos-HPT. Official certification for two further label materials made of film – HERMA PP white extra tc (grade 880) and HERMA PP 50 transparent tc (grade 885) will follow next. All these materials are suitable for applying to PET containers and bottles. In the HERMA laboratory, each of the label materials with the new adhesive 62Rpw achieved a wash-off rate of 100 percent according to the strict testing requirements imposed by Petcore which is the European trade association encompassing the entire PET supply chain from manufacturers to users and recycling enterprises.

Largely closed material cycle

In the context of sustainability, the recycling of PET containers and bottles is an especially interesting topic. According to a 2017 study commissioned by the German Nature and Biodiversity Conservation Union, and conducted by the Institute for Energy and Environmental Research (Ifeu) of Heidelberg, “PET is the only plastic which, even as a post-consumer material, can be converted by appropriate recycling methods into recovered pellets that meet the statutory requirements governing direct food contact.” Above all, PET can be recycled not only once, but in principle an infinite number of times. They added: “It is highly probable (98 per cent collection rate in Germany) that material originating from a disposable PET bottle and re-used in another bottle will also become available for a further use. From a purely technical perspective, multiple recycling is restricted only by the accumulation of additives in the PET.” And in the view of the authors, if the material remains in a largely closed loop, the ecological balance is positive as well.

All contaminants removed

HERMA’s special multi-layer adhesive 62Rpw makes PET recycling simple, efficient and therefore affordable, because it aids the complete and rapid removal of the labels during washing as part of the recycling process. “The label’s ability to remove all the contaminants at the same time, including printing inks in particular, is a key part of the solution – not only in regards to the labelling of containers and bottles, but also in the recycling process,” said HERMA’s Head of Development, Dr. Ulli Nägele.


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