Circular Economy / 04.07.2022

Let’s change the conversation about multilayer PET

Let’s change the conversation about multilayer PET

A short walk through the supermarket is enough to realize the strong presence of thermoformed PET trays in our daily lives. They already represent more than 20% of PET packaging and, while PET bottles are stabilized, the production of PET trays has increased by 27% in the 2018-2020 period. PET trays have a high sustainable profile since incorporate an average rate of more than 50% recycled content, they can be recycled and, due to their layered architecture, are able to respond to challenges posed by food waste and global warming.

Why do PET/PE thermoforms cover half of the market?

The main reasons that explain the roughly half market share of PET/PE thermoforms are the following advantages of this type of materials combination:

  1. Better base-lid sealing ensuring closure effectiveness
  2. Higher packaging speed, provided by the effectiveness of the PE-PE sealing, which requires less time to be processed and lead to a high productivity in the packaging line.
  3. Easy to incorporate a PE / EVOH / PE barrier layer on both the top lid
  4. Lighter packaging solutions can be achieved.

It should be also considered that PET/PE structures with an EVOH barrier are needed to protect/assure food proprieties and shelf life of products, not only to avoid food waste but also to avoid the increasing on the consumption of more resources and materials (because of the need to replace more times the products at supermarkets with all the logistic demand and environmental footprint associated). PE functionality in packaging works also as water/moisture barrier and EVOH as oxygen barrier, hence both materials are needed to extend product life.

When is it possible to go from multi to mono?

Everyone agrees about the necessity of using easy-to-recycle mono-solutions when possible. This “when possible” is referred to the fact that the change to mono solutions must guarantee the same functionality as PET/PE solution regarding closure effectiveness and the compliment of recyclability guidelines (DfR). It is worth to remember that proper packaging eases recycling, but, most important, reduces food waste by extending the shelf life. Beyond ethical considerations, this point is really concerning due to the high environmental impact of the goods and food scarcity.

The packaging industry of high barrier necessities products, sliced cold cuts and greasy food products for instance, tried to switch from PET/PE to MonoPET solutions without success. It seems that MonoPET solutions for this type of products do not attain, for the moment, the requirements needed for ensuring closure effectiveness during manufacturing, especially in aqueous atmosphere and/or greasy products, therefore not achieving conservation properties demanded for water-air tightness, among other things. In addition, MonoPET solutions do not work and are not useful for Form Fill Seal systems

That I, monolayer trays are recognized as an optimal solution when no barrier or low barrier is needed, but multilayer trays offer the best solution for high barrier applications. It should be noted that monoPET solutions have its own problems related to additives for enhancing barrier functionality. MonoPET is not the same as recyclable

What are we talking about when we talk about recyclability?

According to the low capacity currently available for the recycling of PET trays in Europe (either mono or multi), this type of plastic product is considered in some documents and publications as “technically recyclable” but not “practically recyclable” yet.

The big problem is that other and more general definitions of “recyclable” packaging, e.g. Ellen MacArthur Foundation (1), only consider as “recyclable” those packaging that have achieved a successful post-consumer collection, sorting and recycling proven to work in practice and at scale. The perverse result is that any type of new packaging is considered “non-recyclable” (even if there is an available technology in the market for its recycling) since it will lack, for a simple matter of time, of the appropriate infrastructures for collection, sorting and recycling. In other words, it obviates the need to develop the infrastructure for the collection, sorting and recycling of any type of new or relatively new packaging, compared to the historical and older ones, such as PET bottles, which count on these because it has had years to develop them.

The key question is that companies need a critical mass of a type of material and/or packaging to invest in the design and building of the recycling process and facilities and that process takes several years. Additionally, if a type of packaging is indicated as “not recyclable” the interest and willingness from investors critically decrease.

Fortunately, as it is stated and shown in recent publications and conferences(2), PET thermoforms recycling capacity (for all, mono and multilayer solutions) is increasing exponentially and will continue doing it in the following years. So for PET trays the threat of falling into that perverse loop due to this limiting approach is less than for new or relatively new other types of packaging.

Why is it crucial to count on recyclability guidelines for PET thermoforms?

Circular economy requires recycling and waste prevention to keep materials in the production circuit and minimize the use of resources. In practice, the recyclability of a container starts with its design, followed by the way it is collected, sorted and presented for recycling. In this sense, the PET thermoforming sector must join efforts to create the necessary critical mass in the post-consumer waste stream of PET thermoforming to make it scalable in a profitable way and ensure that when waste reaches the PET tray recycling facilities it will be recyclable.

For the latter, the Plastic Sense Foundation published a document of guidelines to guarantee the recyclability of thermoformed PET containers, both monolayer and multilayer, in 2019. As an active member of the Petcore Thermoforming Working Group and in order to promote a harmonized European version of the guidelines fully aligned with the guidelines of the European Commission on the circular economy of plastics, the foundation made this document available to the technical group as an initial base draft to work on a year ago.

The DfR guidelines, that were developed together with companies in the value chain, reflect the state of the art of commercial technologies currently operating in Europe, regardless of whether they operate in one European country or in several, and show the commitment of the industry to the objective to make all PET thermoforms recyclable by 2030.

How can the recyclability of a PET tray be proven?

Retray is a certification scheme of the plastic sense foundation to consolidate a circular economy model in the value chain of thermoformed PET packaging by means of the quantification of recycled material content and the verification of its recyclability.

This certification recognizes and disseminates the work of those companies that introduce, as a secondary raw material in their production processes of manufacture or use of sheet and/or thermoforming, both monolayer and multilayer, transparent recycled PET from recycling processes in the tray-to-tray circuit approved by the Foundation.

RETRAY has two aspects: as a process certification (RETRAY Process) and as a product certification (RETRAY product) and, therefore, the same company can obtain more than one certificate, depending on the number of facilities and products it wants to certify. Specifically:

  1. The RETRAY Process is given to the manufacturing processes of sheet, sheet + thermoformed body, thermoformed body or packaging.
  2. The RETRAY Product certification is granted to specific products made of PET sheet, rigid thermoformed bodies (base, lid) or packaging manufactured in the facilities that have the previously detailed processes already certified.

All companies interested in verifying the recyclability of their PET sheets, thermoforms and trays, in accordance with the recyclability guidelines published by the Foundation, can do so through Retray Product. Verification of compliance with the guidelines is carried out by an Authorized Laboratory.

Contact us through for more information.

(1) According to this foundation, packaging or packaging component is recyclable if its successful post-consumer collection, sorting, and recycling is proven to work in practice and at scale.

(2) “PET market in Europe state of play 2022. Production, collection and recycling”, EUNOMIA; “Recycling PET thermoforms working group. Design guidelines and last technical developments”, Session 4 “Working Groups update”, Ana Fernández, KP