Has aluminium multilayer packaging passed its sell-by-date?

Single use plastic, the brands that use it and the companies that make it, all came in for a lot of criticism at the World Economic Forum.  Whether it was the outrage caused by Coca Cola saying that customers still wanted PET bottles, or Al Gore calling for public action to stop plastics manufacturers building new plants, the message was clear. But although we can all take a ‘bag-for-life’ to the supermarket instead of using thin plastic ones, there is no easy option to replace high performance food packaging. 

Conventional multilayer laminated packaging has been developed to provide the oxygen and moisture barriers that ensure food stays fresh during distribution and storage.  Aluminium foil provides the best performing barrier layer.  But the packaging is hard to recycle.  The layers have to be separated and then the aluminium can be too thin to recycle. 

Europe has introduced regulation requiring that all packaging must be recyclable by 2030. The definition of recyclability is still vague and materials vary in how many times they can be successfully recycled. The reality of much plastic recycling is ‘downcycling’ to a lower grade application followed, after a few cycles, by incineration. Paper is also degraded during the mechanical recovery process of recycling. In contrast, aluminium beverage cans are infinitely recyclable, with only small losses and no effect on its properties. These differences are not yet recognised by regulation.

Polymer manufacturers and flexible film producers are now launching new laminates that are recyclable. An oxide coating or a thin layer of specialist polymer has replaced the layer of aluminium foil. Alternative forms of the same polymer are substitutes for the layers of different polymers in conventional multilayers, so the whole laminate can be recycled as one. So layers of, for example, low and high density polyethylene provide the heat sealing and strength needed to make durable pouches and sachets, whilst being compatible with the standard for ‘recyclability’ drawn up by recycling and waste management companies. The coating or light weight polymer layer, together with any inks, dyes and adhesives, come in below the 5% by weight of ‘other materials’ which is allowed by recyclers. For higher temperature applications, layers of cast and orientated polypropylene are available.

Paper packaging is undergoing a similar makeover. Specialist barrier coatings are replacing the aluminium layer in paper and card multilayers. Last year Nestlé launched a 100% recyclable paper wrapper for its YES! fruit and nut bar, with barrier properties provided by a specialist polymer coating that is  ‘washed away’ during the standard paper recycling process.

However, it is likely that the new coatings will not provide quite as good a barrier as the conventional layer of aluminium foil. Consumers and retailers will probably have to accept shorter sell-by dates for some products, which is a small price to pay for recyclable packaging. Other products may be over packaged anyway, as brands have opted for the industry standard aluminium foil laminate, because alternatives were not available. 

As more people are living in cities and food has further to travel, we can cut down on packaging but we cannot do without it. But we can increase recycling. Aluminium cans may be better than plastic for beverages. But for food, plastic and paper are showing that without aluminium foil they still have a long shelf life.

Published: 28 January 20

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