Written by Laura Clark and Jeremy Teachman
thoughtleadership
Enhancing PET Recyclability
through Ink and Label Innovation
The expectation among many consumers is that the PET bottles
they divert into the recycling stream are transformed into new
bottles. This not only keeps those bottles out of the local landfill,
it also provides a closed-loop and sustainable source of material
for new bottles.
While that is certainly the goal of brand owners, converters
and recyclers, it is too often not the reality. During the recycling
process granulated bottles go through a separation tank to
remove contamination in the form of non-PET materials, such
as caps and labels, using the density of water to separate PET
material from contaminants.
Traditional pressure sensitive adhesives and shrink sleeves
typically do not separate completely causing contamination
to the PET. Instead of food-grade recycled PET that can be
upcycled into new bottles, the process too often yields lower
grade PET that must be downcycled into carpet fibers and pallet
stripping, which have one life before being placed in a landfill.
The trend in beverage bottling toward increased use of shrink
sleeve and pressure sensitive labels is exasperating the problem
by increasing the volume of label material in the recycling
process. This has put brand owners in the position of having
to balance potentially conflicting demands of marketability and
recyclability (while recognizing that recyclability is becoming
increasingly important to consumers).
The need for the industry to address this situation was made
clear by Mike Schedler, director of technology for the National
Association for PET Container Resources (NAPCOR). “The
popularity of pressure sensitive and shrink labels make it
imperative that they be successfully removed as part of the
standard PET reclamation process to increase their recyclability,”
Schedler said.
Enter the APR
The Association of Postconsumer Plastics Recyclers has
transformed the voices of PET recyclers into testing guidelines
that can assess the impact of labels and inks on the yield of
food-grade recycled PET. The guidelines focus on recyclability
by ensuring there will be no negative impact from labels or inks
passing through the PET recycling process to yield food-grade
recycled PET.
The APR testing protocols allow specific label, ink and
adhesive combinations to be tested for recyclability prior to
manufacturing. While the testing requirements have been
defined for several years, the last year has seen renewed interest
in the testing protocols as beverage brands are beginning
to specify that product packaging pass APR testing prior to
production.
Material Innovation
Included in the APR guidelines is the recommendation specific
to labels to use filmic material that has a density of less than
1.0 along with adhesives that separate easily during the
washing process. Several years ago this would have presented
a challenge for brand owners as those materials were not
available.
Fortunately, new materials, such as Avery Dennison’s
CleanFlake pressure-sensitive and roll-fed-shrink (RFS ) labels,
have emerged that are designed specifically to meet the APR
requirement and enable bottle-to-bottle recycling. As pressure
sensitive labels have traditionally limited PET recyclability into
food-grade recycled PET due to adhesive contamination, the
adhesive on these new materials is designed to adhere to the
PET bottles until end of use when it can be switched off in the
PET recycling process to prevent contamination. A topcoat can
be incorporated to support conventional printing techniques. In
addition, a floatable machine direction orientation shrink film is
www.label.averydennison.com
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available, which can be separated easily from the PET flakes in
sink and float process.
These materials have removed a significant barrier to effective
PET recycling; however, they must be matched with the right
inks in the right design to successfully pass APR testing and be
produced within current converting and handling processes.
Ink Innovation
Achieving APR requirements via ink and coating design and
selection, while maintaining the other current end-use and inprocess performance requirements that are critically important
to converters and brand owners, is often a delicate balance.
In addition to the choice of substrate, APR requirements can
be impacted by the application method and printing process,
graphics, and the label converting process. In many cases,
new ink products may be required to meet the full set of APR
specifications without negatively impacting the converting
process and finished label quality.
There are both solvent-based and energy-cured systems that
have displayed positive results in meeting APR guidelines.
Water-based systems have presented a more difficult challenge
to the APR product resistance requirement while still maintaining
other end-use and production process performance attributes.
Work is ongoing in this area as water-based flexographic inks
represent a significant segment in the production of pressure
sensitive labels.
As with any label or packaging application, each specific
package must be verified to meet all of the requirements. A
special overprint varnish (or coating) may be needed to meet the
APR guidelines. Similar to the inks, varnishes have requirements
related to adhesion, flexibility, gloss, block resistance and slip
that could affect their use. Using a primer has proven to aid in
meeting APR requirements in several cases.
The amount and type of ink coverage on the label also
influences the result of the testing for ink bleed and discoloration
of the PET flakes. Not surprisingly, higher ink coverage is
typically associated with more discoloration. Clear labels that
employ heavy application weights of opaque white inks as a
background for additional graphics can negatively impact testing
results.
Partnering for Success
Packaging innovation, achieved through ink and label
technology, is required to minimize contamination and increase
the yield of food-grade recycled material. The bottle recyclability
tests outlined by the APR were designed to simulate the plastic
reclamation process. Among other things, they can point out
potential issues caused by label inks discoloring PET flake in the
contamination process.
By encouraging label material and ink providers, along with
printers and designers, to work together prior to manufacturing,
brand owners can develop product packaging that meets
product requirements while enabling bottle-to-bottle recycling.
These solutions can be achieved today without compromising
marketability or modifying bottling lines.
Laura Clark is the global market director, Beverage, at Avery
Dennison. Jeremy Teachman is field marketing manager
at Sun Chemical. Avery Dennison and Sun Chemical have
worked together to develop beverage labeling that meet APR
requirements.
15047, 03/15, PDF
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