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Recycling of Plastic Thermoformed Articles

Posted on 9/19/2013 10:00:47 AM By Jeff Timm
  

Much has been written in this packaging blog about end-of-life options for materials used in packaging; compostability, biodegradation, wastes-to energy and recycling being the major avenues.  Of all the materials used in packaging, plastic continues to be the one consumer area receiving the most negative end-of-life press, with litter issues, low recovery rates in some categories and plastic bag/ food service article bans.  It is good news to know that a new post–consumer plastic recovery category has recently gained the critical mass necessary to be considered as a major source of recovery opportunity.  


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Photo Source: www.greenerpackage.com


Moore Recycling Associates has confirmed that PET thermoforms are “officially” recyclable.  Moore Recycling Associates is the originator and “keeper” of all recycling statistics in North America.  What this means is that manufacturers and brand owners can now claim that PET thermoforms are recyclable without qualifiers on their packages according to the FTC Green Guides.  The Green Guides state that a material/process type category must have 60% of the U. S. consumers or communities with access to local recycling infrastructure that accepts the category for recycling in order to claim category recyclability.  According to Moore, 61.8% of the U.S. population has recycling access to PET non-bottle rigid (trays/clamshells/cups) articles.  This is a tremendous success story in that in only three years PET thermoforms has gone from being primarily landfilled to being collected for recycling in the majority of U. S. community post-consumer recycling programs.  This was a collaborative effort realized by many stakeholders at all levels of the value-chain with the initial impetus provided by Chandler Slavin, Sustainability Coordinator, Dordan Manufacturing Co., Woodstock, IL who in 2010 challenged the thermoform/recycling industry with her analysis and report - Recycling Report: The Truth about Blister/Clamshell Recycling in America with Suggestions for the Industry©

For comparison, the material type category - PET bottles/jugs & jars with caps have a 94.0% recycling access.

While the post-consumer recycling of PET thermoforms is a wonderful leap forward adding to the recovery of plastic materials in the U. S., it is part of a more complex set of issues that still need to be addressed and resolved.  The first of these issues is that PET is not the only material used in plastic thermoforms.  Polystyrene (PS & HIPS), polypropylene (PP), polyvinylchloride (PVC), cellulous acetate (CA) and polylactic acid (PLA) are all clear materials like PET and offer the brand owner packaging alternatives based on desired properties.  In addition, there are other non-clear materials such as polyhydroxyalkanoate (PHA), low-density polyethylene (LDPE and LLDPE) and a host of other mostly bioplastic alternatives like PLA/starch, algae based and other blends that offer thermoform advantages again based on the desired brand owner’s end-use performance requirements. 

Clear vs. non-clear and the multitude of different polymers presents additional complexities in sorting for recyclers.  Unpigmented PET has the highest value and the widest variety of end-use applications. All other colors, transparent and opaque, are less desirous.  Inclusion of nucleating agents, hazing agents, fluoresces, and other additives for visual and technical effects can also cause issues with recycler’s feedstocks and limit the value recyclers obtain for the material. 

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Photo Source:  Plastic Technology & Placon Corporation

As already noted the curb side mixed stream pick-up approach is very common with recyclers in the U. S.  Even though at curb side recyclers might pick-up mixed streams for recycling they almost always separate the material in the recovery process to obtain the highest value for the plastic recycled resin.  By adding more clear thermoforms to the recycle mixed stream another set of sorting complexities is added to the total recovery process.  The highest value for recycle stock is single plastic resin clear material. With more clear mixed thermoform materials recycled there is additional increased consumer confusion in the plastic identification process that is sure to occur.  This is bourne out in the Moore report which indicates the following about other competing thermoformed materials – PP, PVC, HDPE, LDPE, PS and other non-bottle rigid articles.


Material Type

Clarity

% of U. S. Population w/Recycling Access

HDPE non-bottle rigid (cups/tubs/containers)

non-clear

62.3%

PP non-bottle rigid (cups/tubs/containers)

non-clear

58.4%

LDPE non-bottle rigid (tubs/lids)

non-clear

57.6%

PVC non-bottle rigid (blisters/clamshells)

clear

57.0%

Other non-bottle rigid

?

54.7%

PS non-bottle rigid (cups/bowls/clamshells)

Clear

53.7

Various bioplastics-PLA, PHA, etc.

?

not tracked


As these additional plastic resins increase in volume, once they reach the 60% recovery access level, the level of recovery complexity increases with each new material added to the recovery stream.  The chance for cross-contamination rises with more material variety.  Even small levels of contamination, less than 2%, of some plastic resins with other plastic resins can severely decrease the value of the plastic resin recycle bale and render it useless for many high and mid-level recycle end-use applications.


Clarity and cross contamination are not the only issues associated with recovering and recycling PET thermoforms.  The Association of Postconsumer Plastic Recyclers (APR) has produced a Design for Recyclability Guidelines - Technical Guide for Creating Recyclable Plastics which in great detail guides the product designer through the process of designing a thermoform product that will be the most compatible in a recycle stream.  This APR Guideline document covers many more plastics than just PET.  Some of the APR Guideline highlights for PET thermoforms are:


  • The original PET resins used to make PET bottles and PET thermoforms are different.  Thus, they usually are not mixed together in the recovery process although they might be collected together at curb-side.  This maintains the highest possible value for the specific categories of materials collected.  Additionally, if the mixed RPET is to be used to make new PET articles, the properties will be less than if the RPET was not mixed (PET bottle resin and PET thermoform resin).  The intrinsic viscosity (IV) of the RPET could vary bale to bale based on the percentage of each resin type in the total which would cause consistency problems in meeting end user requirements if mixed.
  • Labels, adhesives, additives and treatments used either during the manufacturing or use of the package, or in the case of processed scrap during a previous intended purpose, can have serious impacts on the quality of the post consumer recycled PET (RPET) produced.  APR protocols are available to test for compatibility.
  • The basic design guidance to consider when making material choice for thermoforms is to consider its general compatibility with the base resin (PET) or the removal efficiency in conventional water-based separation systems that separate plastics by density. Attachments may include labels, seals, coatings, and layers. PET has a density or specific gravity greater than 1.0 (the density of water) and will sink in water-based separation systems.
  • Other non-PET plastic enclosures, liners, and labels may be included in thermoform packaging as long as all such items are completely compatible with the clear PET thermoform (no printing, made of the same PET resin) or made of materials that float in water.
  • Some label inks bleed color when agitated in hot water and can discolor PET regrind in the reclamation process, diminishing or eliminating its value for recycling. The APR and NAPCOR have developed a testing protocol to assist label manufacturers in systems.
  • Direct printing and decoration on PET should be evaluated using APR protocol.
  • Some PET thermoform designers use additives to meet the requirements of specific product applications. Additives to PET thermoforms which cause the PET to discolor, fluoresce, and/or haze after re-melting and solid stating, should be avoided unless means are readily and economically available to minimize the effects. Similarly, blends of PET and other resins are undesirable unless they are compatible with PET recycling. Recognized additives used for thermoforms include the following and each should be examined by the PET Thermoform Guidance Document to show the effects on PET recycling:
    • Denesting agents
    • Anti-stat agents 19 of 33
    •  Anti-blocking agents
    • Anti-fogging agents
    • UV barrier or stabilizer agents
    • Anti-slip agents
    • Heat receptors
    • Lubricants
    • Optical brighteners
    • Degradable additives (photo, oxo, or bio)

Where does all this lead us? 


It is actually quite simple, but as we have seen the devil is in the details.  In order to have a viable recycling marketplace you need good quality consistent recycled material – supply and customers willing to pay for recycled materials to make new items – demand.  While recycled PET thermoforms are a great success story, supply still does not match demand.


Because most of the municipal recovery facilities (MRFs) in the U. S. are run by governmental agencies not chartered with developing end-use markets for recycled materials and the whole process lacks true market drivers since the costs associated with recovery are often subsidized by local governments the system does not exist in a true competitive market driven setting.


Recycling in the U. S. needs a national collaborative plan created by stake holders.  Not a subsidized situation coupled by local often conflicting local laws and bans.  Back in the 60’s industry, science and the government came together and landed a man on the Moon.  A lofty accomplishment!  I’d just like to see a clear, mutually-agreed upon path to get an empty bottle of soda or a PET clamshell used for take-out salad out of your hand into a MRF and repurposed into another article where all points on the value chain make a fair and acceptable profit.

Links:


Federal Trade Commission – Green Guides

FTC Green Guides Summary

Dordan Manufacturing - Recycling Report: The Truth about Blister/Clamshell Recycling in America with Suggestions for the Industry©


APR – Design for Recyclability Guidelines - Technical Guide for Creating Recyclable Plastics


More Information:


Association of Postconsumer Plastic Recyclers (APR)


Dordan Manufacturing


Federal Trade Commission (FTC)




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