In plastics recycling, we often discuss strategies to efficiently collect and process more resins and packaging types. But as we work to grow and diversify the recycling stream, we shouldn’t lose sight of critical evolutions that have occurred in a longtime standby of our sector: PET packaging.

And when it comes to PET, one of the most pressing con­cerns is label technologies. Not surprisingly, the type of labels on plastic packaging can greatly affect the recycling process. In recent years, brands and packaging stakeholders have begun employing new methods of creating and displaying their labels in an effort to reduce costs and make products stand out on the shelf in front of consumers.

The Association of Postconsumer Plastic Recyclers (APR) and other concerned industry players have worked hard to determine how different labeling systems are affecting the plastics recycling process. What follows is a rundown of the findings to date and sug­gestions on how label technology and recycling can move forward together.

A Trio of Approaches

There are currently three widely employed label types used for PET packaging: wrap-around, full-wrap shrink sleeves, and plastic film pressure-sensitive labels. Each one of these label variations demonstrates different levels of performance when recycled, and it’s helpful to understand exactly what each label type entails.

The wrap-around label is the most commonly utilized method for beverage containers. The polyolefin film labels are wrapped around the bottle and fixed in place with a small line of hot melt adhesive. In many cases, the printing is done on one film surface and then laminated to a second film so that the ink is sandwiched between the two layers.

The APR’s “Design Guide for Plastics Recyclability” provides packaging designers valuable information about how packages can be developed to have minimal impact on the recycling process, and the guide details the following as the preferred practice for recyclers working with PET bottles that have wrap-around labels:

• The hot caustic wash water melts and disperses the hot melt adhesive, releasing the label from the bottle.
• With the ink laminated between two layers of film, the ink cannot stain the wash water or the PET flakes.
• Because the film is olefin-based, it will float in water, and is readily separated from the PET that sinks in water.

Posing Challenges

Full-wrap shrink sleeve labels in use today differ from their wrap-around counterparts because they typically cover a PET bottle from the closure down to the base of the container. From a recycling point of view, these labels pose challenges for several reasons:

• Sleeved clear PET bottles are often seen as colored bottles by auto-sortation equipment and ejected from the recycle stream.
• The most widely used label stocks are PETG or even PVC, which sink in water with the PET bottle flake and are difficult to separate from the PET in the widely used sink-float process step.
• The inks on sleeve labels have tradition­ally not been designed to have good adhesion in hot caustic wash water and can bleed into the wash water.
  
  

The APR encourages measuring the recy­cling impact of shrink sleeve and pressure-sensitive labels (more on these below) using laboratory-scale testing process and evaluation criteria, which are covered in full in the APR “Critical Guidance Docu­ments.” Avery Dennison and Polysack, two current APR member companies, now offer commercially available labels that meet the strictest test results criteria in the “Sleeve Label Guidance Document.” In addition, American Fuji Seal and UPM Raflatac now offer sleeve label materials that are recognized by the APR for meeting critical guidance.

Testing from the APR and these com­panies has shown best recycling performance for full-sleeve labels occurs when:

• the label floats in water;
• ink adhesion on the label is retained during exposure to hot caustic wash water; and
• printing on the label covers no more than 75% of the bottle surface area so that NIR (near-infrared) and color auto-sorters can clearly identify the clear PET bottle beneath the label.
  
  

Clearly, these types of labels can be fully integrated into the recycling stream, but pre­cautions need to be put in place by manu­facturers, and the cooperating companies understand that point.

“Finding a label solution that can maintain the integrity of the PET recycling stream is vital to the practices of brands and retailers who want to reduce the environ­mental impact of their packaging,” says Rosalyn Bandy, senior sustainability man­ager at Avery Dennison. “The APR Critical Guidance Documents have enabled Avery Dennison to supply label constructions that help brands and retailers meet their sustain­ability goals. It’s not just about having zero impact—it’s about bringing value.”

Pressure Pioneers

The final label option is the pressure-sensitive approach, which can use either a paper or polymer film substrate. The label is printed on one side of the label substrate, and a layer of adhesive is applied on the en­tire back side of the label to firmly adhere it to the package. Pressure-sensitive labels are used in a variety of PET packaging applica­tions, including beverage, personal care, food, and home-cleaning products. They are also widely used on PET thermoformed packages.

Adhesives are primarily selected to meet brand-owner needs for adhesion in hot, cold, and wet environments. In most cases, the impact of the adhesive, ink, or label on recycling has not been evaluated. However, Spear Label and the Kennedy Group, also APR members, are suppliers of pressure-sensitive film labels and have em­ployed the “Pressure Sensitive Label Critical Guidance Document” to demonstrate that their label technologies meet the strictest test result guidance contained in the protocol. Test data demonstrates that these firms’ labels have negligible impact on recycling, in part because they:

• release cleanly from the PET con­tainer, leaving no adhesive residue on the bottle;
• leverage label stock made from an olefin film that floats and is easily sepa­rated from PET; and
• use ink that adheres to the label in the hot caustic wash step and so does not “bleed” into the wash water and create risk of staining the PET.
  
  

These stakeholders have vowed to continue to push forward the recyclability side of film pressure labels. “The Kennedy Group is committed to developing innovative prod­ucts that promote recycling and sustain­ability,” says the Kennedy Group’s Pat Kennedy. “With the introduction of PureVue, we’re complementing our family of pressure-sen­sitive labels with a product that is ideal for environmentally conscious brand owners. Our goal is to work with organizations like the APR to help brand owners meet their corporate sustainability objectives.”

And what about paper pressure-sensitive labels? These products are widely used on PET thermoforms. As an industry, we want to collect and recycle this packaging type, but the paper labels can have an especially negative impact on PET recycling. The paper can “pulp” in the wash step and release ink into the wash water. In addition, the adhesives used can be difficult to remove from the PET surface.

The APR recently created a protocol for evaluating PET thermoform labels and adhesives for compatibility with recycling to encourage label suppliers to develop labels that have the lowest impact on recycling. There are now a few sources of paper label stock that perform well in this assessment. Avery Dennison, Green Bay Packaging, UPM Raflatac, and Wausau Coated Products offer this type of paper label. The APR encourages those that produce or specify labels to use the label stocks listed on the APR website (www.plasticsrecycling.org).

Continuing Efforts

The packaging industry’s development of new sleeve and pressure-sensitive label innovations seems set to continue. Fortunately, many members of the label value chain have been working closely to better understand and solve the challenges of new labels when it comes to recycling.

Sun Chemical and Eastman, for example, are working together to develop an approach to creating a seam on sleeve labels that will allow the label seam to separate when a bottle goes through a whole bottle wash process. At the same time, companies selling auto-sortation equipment are making improvements to equipment and software to better manage labels, and ink suppliers are using APR test methods to develop new label inks.

The recycling industry welcomes these innovations and strongly encourages their adoption by brand owners. The APR, meanwhile, will continue efforts to work with the label industry to create solu­tions for challenges to plastics recycling.

Those APR efforts, in fact, are becoming increasingly for­malized and effective. The Design Guide and Critical Guidance Document initiatives mentioned earlier are both components of the APR’s Champions for Change Program, which guides package de­signers and innovators to develop packaging compatible with today’s recycling processes. The program provides standardized laboratory evaluations to assess the impact of a pack­age or package component on recycling.

In order to drive packaging innova­tion and qualify new materials, the APR encourages brand owners to request that suppliers provide data developed through these tests. Companies that meet the strictest test result guidance given in the Critical Guidance Documents are formally recognized. Stakeholders in the PET packaging field are indicating they are paying attention to the recycling industry’s efforts to examine the impacts of label types, and those companies are increasingly becoming a part of the actual research.

With that type of cooperation, we can ensure labels and recycling processes evolve together. “Having been involved with the APR and the development of these test methods, we are happy to see the response and success to innovate labels,” says Kris­tina Hansen, project manager at Plastics Forming Enterprises. “These efforts will raise the quality of the recycling stream.”

About the Author:

John Standish is technical director of the Association of Postconsumer Plastic Recyclers. He can be reached atjohn@plasticsrecycling.org.

This article was originally published in Resource Recycling and Plastics Recycling Update magazines in 2014. Used with permission.