Recyclability and Redesign Challenges in Multilayer Flexible Food Packaging—A Review

Abstract

Multilayer flexible food packaging is under pressure to redesign for recyclability. Most multilayer films are not sorted and recycled with the currently available infrastructure, which is based on mechanical recycling in most countries. Up to now, multilayer flexible food packaging was highly customizable. Diverse polymers and non-polymeric layers allowed a long product shelf-life and an optimized material efficiency. The need for more recyclable solutions asks for a reduction in the choice of material. Prospectively, there is a strong tendency that multilayer flexible barrier packaging should be based on polyolefins and a few recyclable barrier layers, such as aluminium oxide (AlOx) and silicon oxide (SiOx). The use of ethylene vinyl alcohol (EVOH) and metallization could be more restricted in the future, as popular Design for Recycling Guidelines have recently reduced the maximum tolerable content of barrier materials in polyolefin packaging. The substitution of non-recyclable flexible barrier packaging is challenging because only a limited number of barriers are available. In the worst case, the restriction on material choice could result in a higher environmental burden through a shortened food shelf-life and increased packaging weights.

The Frontier of Plastics Recycling: Rethinking Waste as a Resource for High‐Value Applications

“…[ 94 ] Typically, they consist of polyolefin base materials co‐laminated with a barrier film and, for example, an outer PET‐based decorative layer. [ 95 ] In a monomaterial packaging instead, a single polyolefin film would be used. However, lacking critical barrier properties, for example, for oxygen or lacking mechanical strength, either much higher film thicknesses and as such polymer amounts have to be used, or alternative barriers must be applied that do not add a significant share of foreign material, for example, by gas‐phase deposited inorganic thin films.…”

“…Reaching sufficient performance always remains critical and besides improved recyclability, low weight, and highly efficient protection of perishable ingredients such as food, need to be optimized jointly in a life-cycle assessment to address sustainability. [95] Designing for full recyclability in the polyolefin stream can also be addressed by restricting other materials to stay within practical or theoretical compatibility limits described in guidelines, [96,97] or potentially by already incorporating compatibilizer additives in respective laminates needed for their high value mechanical recycling. [59] As an alternative to monomaterial designs, laminates or assemblies of different materials can be converted into monomaterials if they can be disjoined (Figure 15) by a selective trigger during pre-treatment.…”

Tailor-Made Functional Polyolefins of Complex Architectures: Recent Advances, Applications, and Prospects

“…The problem of plastic waste is so vital that their weight in the ocean will be as much as fish by 2050 if no solutions are found for their recycling or biodegradability . Although the plastic materials are under pressure to be redesigned to meet recyclability criteria, there are some challenges in polyolefin recycling, such as the product low value and the lack of secondary markets, problems in sorting the mixed waste, and the thermodynamically unfavorable C–C bond dissociation. , Generally, polyolefin recycling technologies are classified as primary or re-extrusion, secondary or mechanical, tertiary or chemical, and quaternary or energy recovery. , Degradation chemistry paves the way to generate tunable functional groups with a raised value simulating plastic recycling.…”

Cereal and Confectionary Packaging: Background, Application and Shelf-Life Extension

“…The available material classes cover mainly glass, metal, paper/board, (bio)plastic, as well as composite materials (laminated, coextruded, blended). Composites can consist of two or more components combined to form, for example, multilayer materials (e.g., plastic-coated cardboard) which frequently show superior functional properties (e.g., barrier) and reduced weight [ 31 ], but on the downside also reduced recyclability [ 34 , 35 ]. Touching upon the topic of recyclability, many packaging solutions face obstacles, if it is at the stage of collection, sorting, or in general limited technical recyclability.…”