...[please see yesterday's post for context as today's post picks up where that one left off]...Also invited to participate in the task force meeting was the President of
Plastics Forming Enterprise LLC., who was heavily involved with the development of APR’s
Design for Recyclability Guidelines for PET bottles in the early 1990s. To make a long story short, this guy knows a thing or two about plastics recycling. His company is marketed as “an independent full service testing and R&D company serving the plastics, packaging, recycling and consumer products industries worldwide with a range of services.” As such, he is very well versed in the technical barriers keeping certain packaging/materials from being recycled and how recycling markets are generated and sustained.
His presentation titled “Recycling of PET Labeled Thermoforms and Bottles,” was one of the more precious compilations of insights into the technicalities governing PET bottle vs. PET thermoform recycling I have stumbled upon: For those of you who follow my blog regularly, you will recognize that the approach to PET thermoform recycling (and therefore what is considered a contaminate) has always been ambiguous—do you recycle PET thermoforms WITH bottles or in a separate stream? According to this gentleman, the answer is to recycle PET thermoforms WITH PET bottles eventually; it is just a matter of time, investment, and trial and error until recyclers and buyers gain the confidence into the value of PET thermoform material to sustain the collection and reprocessing there of. Good news, right?!?
What follows are some take-aways from this presentation:
Pressure-sensitive labels are the majority of labels used on thermoformed containers sold at retail. They consist of adhesives, substrate (paper vs. plastic), inks, coating, and laminate.
The known obstacles to recycling thermoforms with label/adhesives include: Sorting/contamination removal, material variability, mechanical engineering issues, misc. technical issues.
The known obstacles to recycling thermoforms with labels include: Look-alike contaminates i.e. PVC thermoform looks like a PET thermoform, wide variability in IV, package shape, direct print, different adhesives, different additives, fluorescence, flake bulk density, paper labels.
There are physical differences between PET thermoforms and PET bottles. While bottles have high IV, high bulk density and a unanimous design and material i.e. thin screw-top PET bottle, thermoforms have low IV, low bulk density, and heterogeneous shapes and material constituents.
The labels on PET bottles are typically plastic; the labels on retail point of purchase thermoforms are predominantly paper and continuously be increasing to plastic.
o It is generally understood that the move away from paper labels is the current issue at hand in the plastics recycling market (see APR’s Design Guidelines, pg. 12).
o However, the practical side of recycling PET thermoforms will need consideration of paper in the future i.e. POP label application.
The APR Thermoform Label and Adhesive protocol follows these steps:
o Apply label
o Grind
o 1st Elutriation
o Wash/Sink float
o 2nd Elutriation
o Plaque
o Analysis
PFE has developed a screening evaluation that focuses on adhesive performance (this takes a label and adhesive that has been applied to a specific package):
o Ground per APR guidelines
o Washed per APR guidelines
o The resulting flakes are analyzed for separation of the label from the flake (paper vs. plastic label impacts this test insofar as paper labels tend to “stick” to flake)
o The resulting flakes are analyzed for impact of inks and the impact of residual adhesive on the flake
In Europe, a common test evaluates the solubility of adhesives; this protocol does not look at the potential impact of:
o Soluble adhesives that have gone into solution during the wash and rinse process and redeposit onto the processed PET flake;
o Residual adhesives that remain tacky are causing problems where labels and flake become stuck together during reprocessing, hindering the removal potential of a given label.
Ideal PET label substrate properties:
o Floatable
o Light weight
o Maintain printed inks
o Physical properties for better separation
Ideal PET label adhesive properties:
o Needs to dissolve into solution and not reapply itself OR
o Adhesive to remain with the label and not be tacky
PFE’s Screening Evaluation is designed to understand three basic areas where label and/or adhesive performance is crucial to meeting the guidelines set by the APR:
o Separation from flake
o Removal through Elutriation and Sink Float
o Adhesive solubility and potential impact on flakes
o Impact of inks on wash water and flakes (if printed)
It was concluded that pressure sensitive labels are a critical part of the entire package. Therefore it should not be isolated as the main indicator of adhesive contamination potential without considering the interaction of the other label components.
Whoa!