24th IAPRI World Packaging Conference: Recyclable Packaging with Good Functional Properties Predominates

Abstract

The 24th IAPRI World Packaging Conference was held in Valencia from 17 to 20 June. This time the host was the Spanish scientific institute ITENE, which at the same time celebrated its 30th anniversary. The conference had no fewer than 150 speakers from various universities and other institutes from 32 countries involved in packaging research. The conference was attended by 300 listeners, many of whom work in the same field. The enormous range of scientific presentations was divided into five segments, each presented during as many parallel sessions. For that reason alone, it was impossible to physically attend all presentations. However, the perfect organization had an equally perfect solution for this with an extensive reference book with all presentations. The five segments mentioned were divided into: Packaging materials; Packaging design and development; Packaging distribution for products; Packaging machines; and Sustainability of packaging in the supply chain and product conditioning and packaging technologies. Although interesting insights were presented in each area, the focus in this article is mainly on developments in the field of packaging materials. Partly to blame for this is the Packaging & Packaging Waste Regulation, which sets a number of strict requirements for packaging to be placed on the market in the European Union (EU) from 2030. This applies to packaging produced in the EU and abroad. Although only the main points are now known and further details will not be known until 2026, packers will still have to get to work. (See sidebar at bottom of page.)

Biobased dominates research A number of common threads were identified in Valencia when it comes to the development of new packaging materials or modifications of existing packaging materials. For example, adding a barrier to a material to ensure that the packaging meets the minimum functional requirements, particularly to prevent food spoilage. In particular, many solutions could be found for biological and biodegradable materials. Possibly in combination with a comparison of the functional properties with those of an oil-based plastic packaging material.

Comparison PE with compostable A good example of the latter was a study led by Prof. Mieke Buntinx from UHasselt. In that study, a comparison is made between two different laminates for thermoforming: an oil-based and a biodegradable multilayer. On the one hand to determine the maximum dilution and on the other hand the associated permeability (permeability) of gases.

The thermal and tensile properties of two commercial multilayer films were compared: an oil-based PE/EVOH/PE laminate and a compostable Ecovio/G-Polymer/Ecovio (~85 µm). Ecovio is the brand name of a PLA/PBAT bioplastic from BASF. Tensile tests were then carried out at selected temperatures to determine the maximum elongation based on the elongation at break. The 70×60 mm2 films were then stretched in the machine and/or cross direction (MD, CD, MD+CD) or 45 degrees. The microscopic thickness resulting from these situations was compared to the thinning in the bottom, walls, and corners of thermoformed trays.

The results show that for both films, as they become thinner, there is a proportional increase in the water vapor transmission rate (WVTR). The PE layers provide a better solution in terms of water vapor barrier than the compostable layers. In contrast, the oxygen transmission rate (OTR) is not proportional to the thinning of the overall film, nor to the thickness of the barrier layer. Here, an improved oxygen barrier can even be seen compared to the base films due to a reorientation of the polymer chains in the barrier layer. This especially applies to PE laminate. This makes it possible to use less EVOH, making the multi-layer film more recyclable. According to Buntinx, this leads to the ultimate conclusion that the biocompostable combination is preferable in dry conditions, because the G-Pol barrier achieves very high oxygen barrier properties at low relative humidity. EVOH in the petroleum-based laminate, on the other hand, is less sensitive to relative humidity compared to G-Pol. Therefore, this is the preferred material for packaging food products with a high/higher(er) moisture content. Buntinx and her team also choose to consciously involve bio-monolaminates in their research for another reason — and despite the fact that there is not yet a collection structure for this in Europe. “Multi-layer packaging materials are still considered highly efficient and environmentally friendly solutions compared to alternatives,” according to Buntinx. “This is because of the sophisticated balance between mechanical performance required for logistics and handling and thermal stability for filling and/or thermal treatment. But also because of the optics for customer attractiveness and sealability, the gas, water, or aroma barrier properties necessary for content retention and a lightweight design. In this way, we can achieve a reduction in raw materials.” However, at the end of their life, multi-layer packaging is currently largely incinerated because it cannot (yet) be recycled in the existing waste management infrastructure based on traditional mechanical recycling. “This contradicts the core principles of a circular economy, especially within the European Union (EU), where plastic packaging is a top priority within circularity initiatives,” Buntinx said. “Given only 39.6% of plastic packaging waste was recycled in 2021, the need for circularity is reinforced by the upcoming entry into force of the PPWR, which sets a 55% recycling target for plastic packaging by 2030.” Design for recycling To comply with these new regulations, design for recycling must be used to reduce multi-layer complexity. “However, when a less complex mono-material solution shows better recyclability but is associated with a higher material use or a shorter shelf life compared to a multi-layer solution, this is actually not environmentally friendly either,” Buntinx noted.

She continued, “Today there is a shift towards minimizing multi-layer material diversity, with a particular preference for polyolefins with limited use of ethylene vinyl alcohol copolymer (EVOH), metallized aluminum layers and aluminum oxide (AlOx) or silicon oxide (SiOx) coatings to provide some height to improve barrier properties.”

To meet the recycling standards according to the Ceflex or RecyClass guidelines, laminates must consist of at least 90% polyolefin to qualify as a mono-material suitable for recycling. Buntinx: “Coextrusion or lamination with EVOH is preferred over AlOx and SiOx, as these coatings are generally less suitable for sterilizable packaging or thermoforming applications.”

Recyclability testing shows that EVOH has a small impact on the recycled material, at a threshold of up to 5% of the total weight of the PE film. Above this limit, an immediate impact on the extrusion process is observed with yellowing of the material, an increase in haze, membranes and black spots, and a frequent bubble break.

Biobased is sometimes the only option Another way to meet circularity for multilayers is better recycling technologies. Buntinx again: “In the near future, a mix of different recycling technologies (that is, high-quality material recycling, chemical recycling into hydrocarbons, and downcycling) will develop in different parts of the world. This evolution will be highly dependent on local regulations and availability of technology.” But even though developed countries have the most efficient technology to recycle multi-layer materials, much of the world will still lack basic waste management and conventional recycling systems.

This is what Buntinx and her team conclude: “Therefore, the use of biobased materials in laminates still offers an opportunity to reduce carbon emissions in the short term and decouple them from the fossil economy. Furthermore, biodegradable food packaging can be thrown away together with food waste and further processed through composting or organic recycling. Biodegradable films also offer better compatibility with compostable fiber-based materials and are ideally suited as a barrier layer for paper packaging. After all, the barrier effect with regard to the packaged product, especially after material processing, remains of primary importance.”