The climate crisis, water pollution caused by microplastics, health concerns – there are enough reasons and thus also a current trend to keep the plastic content of packaging materials as low as possible. Or to go straight for fiber-based materials, such as cellulose.
The major limiting factor for fiber-based packaging in the food sector is, of course, product protection. In the food sector, fiber-based packaging has often been laminated for reasons of shelf life. This plastic laminate on the fiber material can considerably impair its recyclability.
Even where it would theoretically be possible to separate the plastic from the fiber during disposal, this separation option is not used by the majority of consumers. In the case of paper packaging with plastic film, this therefore generally means that the entire packaging either ends up in waste paper or in plastic recycling. Neither is definitely optimal in terms of the circular economy and resource conservation. "A significant example of this separable composite is the classic yogurt cup with a cardboard sleeve, plus an aluminum board and – but less and less lately – a plastic lid. Since it is well known that consumers generally do not separate these packaging components when disposing of them in the yellow bag, the entire cup is also considered to have poor recyclability. This is despite the fact that all the components have very good sorting and recycling properties if they were disposed of separately. That's why there are also developments to make separability easier and easier or to dispense with films completely or as far as possible," analyzes PACOON managing director Peter Désilets.
Research steps on the gas
That was the not-so-good news. However, there is also good news: coating technology in particular is currently developing at a rapid pace. For example, there is now already packaging consisting of almost one hundred percent cellulose, which can keep up with classically foiled variants for some product groups in terms of parameters such as best-before date and product protection. "Exactly which barriers are used there is not readily disclosed. But they can be algae-based variants, plasma coatings, sugar-based barriers or even 'solgel' applications. The number of solutions is diverse and research is being done in many directions. They can be used to achieve very good values for grease, oil or water resistance and, in combination with other board components such as primers, also very good oxygen and water vapor values. However, the highest hurdle is not the plastic barriers, but still the aluminum barriers," says Désilets.
Researchers are also working on a number of processes that solve the barrier dilemma by allowing extremely thin and often biodegradable coatings. Films can now be applied using wet chemical processes, making it easier to use biodegradable materials. The goal is also to apply aluminum or silicon oxide to fiber-based packaging by vapor deposition. This would allow a barrier layer of just 60 nanometers, as demonstrated by the Fraunhofer Institute for Process Engineering and Packaging IVV. PACOON is also tinkering with this, as Peter Désilets reveals, "We ourselves are in contact with barrier suppliers who can apply a barrier of five to 20 nanometers."
Market on the rise
In any case, fiber-based packaging is currently experiencing a boom. More than $425 billion accounted for the global market for these materials in 2022. The industry expects further increases over the next five years, with molded pulp and flexible papers likely to come into focus alongside corrugated board, folding cartons, and specialty papers, for example to establish alternatives for liquid products in the cosmetics sector. According to Desiléts, "These molded fiber packages are on the market in different versions: as so-called dry mold or wet mold packages, i.e. dry molded or wet molded containers. Fiber injection molding, as in plastic injection molding, is also already being tested. And we'll soon see more and more packaging in this area that produces complete hollow bodies from a single mold."
Meanwhile, there is no shortage of unconventional ideas coming out of the start-up world. Which of them will be able to establish themselves in the long term, of course, remains to be seen. Fiber-based materials made from agricultural waste, for example, are considered to have a long-term future. Grass has been around for a few years, so has bagasse, silfie is being tested, hemp is undergoing trials, and straw represents a huge resource volume. In Asia, the use of bamboo fibers and rice straw has not been uncommon for a long time, sugar cane fibers from Latin America as well. What they all have in common is on the one hand the use of a waste product, and on the other hand they are in line with the trend, because wood as a basic material for paper and cardboard is currently also viewed negatively from the point of view of deforestation. Here, these alternative waste materials could provide relief, at the same time still have a lower CO2 footprint and are regionally available in part in large quantities. But it is not only from land that these resources enter the packaging market. Alternative 'fiber materials' such as seaweed or algae also come from water. "The big challenge is the economic viability and the health risks that can be transferred from agricultural residues or even production residues through packaging to the packaged goods. There is also a lot of research and investigation in this area to avoid bringing the next problem into the house," says Peter Désilets.