The Problem: Decoding the ink and coating dilemma in plastic packaging
Inks and coatings are indispensable components of plastic packaging, playing a vital role in communication, protection, and aesthetics. While these elements enhance product presentation and provide essential information, they can also complicate the recycling process.
There are three main classes of food packaging films:
A laminated or multilayered plastic is composed by: inks, plastic films ( sometimes more than one) and adhesives. On the other hand, an inked plastic film is composed of: extruded plastic film, inks and top coating layer.
When a company want to recycle inked, multilayered and/or laminated plastic films, the difference in physical-chemical properties between plastics and other components make it impossible to have a good quality recycled material from it. Do you want to read more about it? follow the next links:
- Recycled plastics qualify as feedstock, but the leap forward is still ahead
- Recycled plastic products- the quality dilemma
- Post-consumer recycled plastic vs virgin plastic.
And if you want to gain a more scientific understanding, check out this paper:
Citation: Ruben Demets, Karen Van Kets, Sophie Huysveld, Jo Dewulf, Steven De Meester, Kim Ragaert,Addressing the complex challenge of understanding and quantifying substitutability for recycled plastics, Resources, Conservation and Recycling, Volume 174, 2021,105826,ISSN 0921-3449, https://doi.org/10.1016/j.resconrec.2021.105826.(https://www.sciencedirect.com/science/article/pii/S0921344921004353)
Plastic film life cycle
The graph is part of the open access report from Plastic Europe. The data reflects the year 2018 for all kind of plastic products.
In the graph, something was excluded but it is vital for the recycling industry. After the waste collection and between the 3 different routes, there is a sorting process. This process defines the ending of each individual plastic film. Due to technical factors this process is the most complicated and expensive in the recycling process of plastic films. Nowadays the market price of the inked plastic films is low, so the sorting is additional pressure on the process that can lead to a financial issues for a company.
Additionally, there are two stress factors in the cycle regarding recycling:
- Some countries like The Netherlands do not have active landfill in their own land. Therefore, the plastic waste has to be managed overseas.
- The applications employing recycled plastic do not utilize 100% of recycled material; rather, the final product incorporates a partial amount, mainly due to technical constraints
What are the issues with the recycled plastic films?
The picture on the left is also part of the open access report from Plastic Europe.
The image portrays the choices available for the plastic films that have been recovered. Out of the 3 recycling options, only chemical recycling possesses the capacity to generate products of superior quality suitable for premium applications such as food packaging. Moreover, the expense associated with chemical recycling is considerable, and its applicability is restricted to a narrow range of plastic categories. At the moment, the other two processes yield recycled plastic films that find utility in applications requiring basic technical demands, primarily serving as low-grade materials, such as brick fillers.
Why the current recycling techniques for plastic films yield low quality recycled plastics?
There exists a multitude of factors driving this reality. The primary two factors encompass the sorting procedure and the presence of impurities within the plastic films intended for recycling. These so called contaminants are primarily linked to the surface of the plastic film. These impurities possess distinctly different physical and chemical characteristics in comparison to the polymers utilized for generating the plastic films. Now the question is: Why is this important?
The recycling of plastic films involves at some point a step called the pelletizing process. This process melts the plastic films at temperatures around 200 C and produces pellets, small plastic balls of 3 mm of diameter. The pellets is the form all the polymers around the world. Due the difference in physic-chemical properties of the contaminants (for example inks) and polymers, the process produces gases and byproducts, resulting in a reduced quality of the recycled plastic end product. In conclusion, plastic films without contaminants in the surface can yield higher quality recycled products.