There are many challenges to mechanical recycling, a complex process that involves many steps and resources to obtain clean recyclate. The adhesives used in pressure-sensitive and glue-applied labels are among the obstacles. Two technology companies are working diligently on finding a solution.
Avery Dennison developed CleanFlake adhesive technology to advance recycling of polyethylene terephthalate (PET) containers. The CleanFlake portfolio features a water-based, recyclable adhesive that cleanly separates during the PET recycling process. Strong, lightweight, transparent, and highly versatile, PET plastic is used for consumer packaging. Yet one of the traits that make PET equally valuable to brand owners is its tremendous potential for recyclability.
The adhesive sticks to the PET bottle until the very end of its lifecycle. The cohesive bond is broken during the sink/float stage of the recycling process. This allows the face stock and adhesive to cleanly separate from the PET, resulting in pure PET flakes, the conservation of virgin PET resources, and less waste going to landfill. Available in clear or white biaxially-oriented polypropylene (BOPP) film face stocks, CleanFlake is the first complete solution to address PET plastic recycling, according to Avery Dennison.
Adhesives get smart under Henkel's tutelage
Henkel’s Adhesive Technologies business unit also is innovating sustainable solutions that will ensure packaging can be easily and efficiently recycled, said the company’s information. Adhesives used in packaging typically make up no more than five percent of the total weight, yet their properties can make the difference when it comes to the overall recyclability of the material.
Henkel has a range of adhesives designed for plastic bottle labeling, such as those commonly used for beverages and laundry detergent. These adhesives enable the clean removal of the label, which means the material separation in the recycling process is more efficient resulting in high-quality recovered materials, said the company in a blog on its website, “How Smarter Adhesives Play a Role in Recycling.”
Henkel also provides solutions for flexible packaging, one of the fastest-growing segments of the consumer packaging industry.
Adhesives play a critical role in high-performance barrier packaging that takes advantage of the best attributes of a combination of materials, including plastic and aluminum. However, notes Henkel, these packages are difficult to recycle by design, “often containing two or more different kinds of materials that cannot be returned to separate streams.” To overcome this challenge, Henkel has been working with Germany-based recycling specialist Saperatec for several years on developing and enhancing customized recyclable adhesives that, together with Saperatec’s technology, enable the separation of the individual layers found in such packaging. This partnership offers manufacturers an innovative and cost-efficient recycling technology that makes it possible to reintroduce production waste consisting of polyethylene (PE), aluminum, and PET into the raw material cycle.
“Based on our many years of experience in the flexible packaging industry, we developed laminating adhesives with the highest standards of food safety, performance, and efficiency,” said Helga Garmann, Head of Product Development at Loctite Liofol Europe. “Our adhesives for the Saperatec process combine all those properties with an optimized separation behavior.”