Recyclability and compostability are two of the ways to comply with the circular economy requirements set by the European Union. In the Action Plan for a Circular Economy in Europe published in 2020, the EU set out measures to make it easier for all existing packaging on the Community market to be reusable or recyclable in an economically viable way by 2030. And, when talking about recyclables, the possibility that they are compostable is also included, since this is a type of organic recycling.
Already in Directive 2018/852, amending Directive 94/62/EC on packaging and packaging waste, measures were included to prevent the production of packaging waste, promote reuse, recycling and other forms of recovery of packaging waste. And, at the national level, measures have also been proposed to meet the objectives set by Europe, such as the draft Royal Decree on Packaging and Packaging Waste, which is expected to be approved by the end of 2022 and establishes challenges in five areas: prevention, reuse, recyclability, compostability and introduction of recycled content in packaging.
To develop more sustainable packaging, the materials used and the design of the packaging itself are mainly taken into account, but they must also cover different functions, such as protecting and preserving the products they contain.
However, in many cases it is not possible to find a single material that meets all the requirements, so we resort to the use of multilayer/multimaterial structures that combine and cover the required properties. These structures improve the thermal resistance of the container, as well as its barrier to moisture or oxygen, which allows the product they contain to be better preserved, extending its useful life and thus reducing food waste.
However, the use of multilayer/multimaterial structures presents problems in their recyclability due to the difficulty in their identification, separation and recycling or valorization, which limit the viability of the applied recycling processes, although progress is being made in innovative mechanical, chemical or enzymatic recycling processes, in which the Itene technology center is also working, to overcome these limitations.
The use of this type of structures is increased in the case of flexible packaging, since it offers various advantages over rigid packaging, such as lower consumption of materials and resources, weight reduction and a high ratio of product per unit of packaging, among others. These advantages have led to an increase in its use, covering more than 40% of packaged foods in Europe and 10% of all materials for product packaging, according to data provided by Flexible Packaging Europe (Key Sustainability Facts).
In this context, there are alternatives that promote innovation within flexible packaging to align with legislative requirements, without losing the benefits presented by the packaging. Among these alternatives are compostable and recyclable multilayer flexible packaging, also proposed by the Ellen MacArthur Foundation (Flexible packaging strategy summary 2022) as tools to promote the circularity of this type of packaging.
Compostable multilayer flexible containers represent a great advance, since thanks to their biodegradable/compostable nature, at the end of their useful life, they can be managed together with organic waste, thus contributing to one of the objectives set out in the new European directives, to reduce plastic waste in landfill.
In the field of biodegradable/compostable materials, polylactic acid (PLA) is one of the most promising compostable bioplastics from renewable sources, capable of being processed by conventional rigid and flexible packaging transformation technologies.
However, PLA still lacks the barrier properties necessary to be used for food packaging with a long shelf life. Therefore, nowadays it is possible to find flexible packaging solutions based on PLA in multilayer format that, by combining with other materials, provide the final solution with the required barrier properties, as is the case of polyvinyl alcohol (PVOH) for high oxygen barrier applications.
In this context, the Itene technology center together with the Viokox company is developing a single-dose multilayer biodegradable/compostable container for cosmetic applications within the RACE4BIO project, funded by the Center for Industrial Technological Development (CDTI) of the Ministry of Science and Innovation.
For this, different technologies are being used, coextrusion and lamination, to obtain the final multilayer structure based on sustainable materials with properties comparable to that of current petroleum-based containers. Through the use of these technologies, it is intended to improve the final properties of biodegradable/compostable materials, specifically, their barrier properties in order to preserve the characteristics and quality of the cosmetic product throughout its life cycle.
In addition to the development of the packaging, another of the challenges of the project is the validation of the biodegradable/compostable packaging with the current Viokox cosmetic formulations. This validation is being carried out through stability and compatibility tests between the biodegradable/compostable multilayer packaging developed and the cosmetic product to be contained in order to evaluate possible interactions that may affect the properties of the packaging during its life cycle.
On the other hand, another alternative to promote the circularity of packaging is recyclability. According to Plastic Recyclers Europe (Recycling Statistics 2020), part of the improvements in the recyclability of packaging should include, on the one hand, the reduction of excessively colored surfaces and, on the other, the reduction of the presence of contaminants in the separation and recycling streams of packaging, such as heterogeneity of polymers, the presence of adhesives, inks and/or fibers.
In this sense, an alternative is the development of formulations compatible with recycling processes. In particular, companies like Samtack already have recyclable and even compostable water-based adhesives in their product portfolio to be able to make all kinds of structures.
Within the R&D in this field, in addition, there is the increasingly present trend of development of monomaterial structures replacing multilayer flexible packaging. In this sense, “monomaterial”, according to the definition of the Ceflex initiative (Circular Economy for Flexible Packaging), is considered a structure that contains up to 90% by weight of the base material and up to a maximum of 10% of other materials or elements included in the final structure of the flexible packaging.
In this line, mainly polyethylene or polypropylene-based solutions have appeared, such as by Constantia Flexibles (EcoLamPlus range), Coveris (Monoflex products) or Enplater with its PPFULL and PEFULL products, along with PET-based monomaterial solutions (PETFULL line).
However, the development of monomaterial solutions is not the only alternative to promote the design of new packaging structures aimed at their recyclability. For example, the use of delaminable layers, the marking of materials or the optimization of processes in recycling are technologies that are currently being worked for this purpose, such as, for example, promoting the separation of the PET layer present in a large part of these structures, offering alternatives in complex structures.
At the national level, within this R&D line and focused on multimaterial packaging materials, there is the Loopack project, funded by the Center for Industrial Technological Development (CDTI) of the Ministry of Science and Innovation. With this project, the companies Lubrizol, Samtack, Enplater and Acteco, which have had the support of the Itene technology center, are developing a flexible packaging with barrier properties for food applications that is easily recyclable.
The ultimate goal is to enhance the multi-material multilayer materials, usually used in food packaging and reduce the amount of packaging plastics in landfills. To this end, work is being carried out on the incorporation of the various technologies studied, such as the integration of markers in the lamination adhesive formulations and the application of barrier coatings and a delaminable primer that allows separating the layers of ink and lamination adhesive from the rest, with the aim of obtaining high-quality recycled materials.
Currently, in addition to the validation by Acteco of the materials obtained, the different technologies targeted by the project are continuing to be optimized to carry out a new pilot test during the autumn of 2022.
Therefore, in the face of increasing legislative restrictions with the aim of reducing the environmental impact of packaging, collaboration is necessary throughout its entire value chain. This collaborative work will allow optimizing and implementing alternatives for the recyclability and compostability of packaging in a more effective way and aligned with each of the actors in the chain.
Proof of this are already existing initiatives to promote this work and increase the circularity of packaging. Ceflex, representing the flexible packaging chain, developments such as HolyGrail 2.0, based on a watermarking system to optimize waste classification, or Recyclass, to promote recyclability and guarantee the traceability of recycled plastic content, are examples of this.