Design principles in flexible packaging to advance the circular economy
Flexible packaging is an essential part of many elements of everyday life. It is a resource-efficient packaging that plays a key role in protecting food and other products, preventing food waste, minimising resource consumption and providing important packaging functions.
Flexible packaging accounts for half of primary food packaging in Europe, while only requiring, by weight, one sixth of the packaging material used. The far-reaching advantages of flexible packaging, such as low weight and thus minimal material usage, mean that it is increasingly being used. However, these properties also mean
that flexible packaging can become more difficult for end-users to collect and correctly sort in order to eventually recycle the packaging.
Flexible packaging is usually easy to bend and can take the form of stand-up pouches, sachets, bags, removable lids and films. Flexible packaging structures can be single or multi-layered and can be made from a variety of materials such as plastic film, paper, aluminium foil or a combination of these materials. The structure can be single-coloured, printed, coated and/or laminated. Flexible packaging is typically used to protect consumer products such as:
- Confectionery & Snacks,
- frozen foods,
- bakery products,
- Fresh produce
- Pet food
- Cosmetics & body care products
- Pharmaceuticals & medical products
Recyclability of Flexible Packaging
For packaging design, recyclability could be ensured by providing the required functionality from a mono-material equivalent if possible, or by ensuring the structure identifies and removes the recyclable material streams. For improved sorting and recycling processes, recyclability could be ensured by identifying materials through improved optical sorting, mechanical recycling process development and emerging technologies.
The focus of this blog article is on mechanical recycling of packaging (recycling process), as this will be the main route for recycling flexible packaging in the short to medium term. Flexible packaging encompasses a wide different format, with each structure and combination of elements designed to support specific packaging functionalities, such as certain gas and moisture barrier requirements or resilience. Even with these specific functional requirements, there are some generic design principles that can be followed to design flexible packaging to support the circular economy.
When the design principles are adopted and implemented, the design and specification process will not lead to increased consumption of resources. For example, increasing the weight or thickness of the packaging may make it easier to achieve the recyclability limits. The decision to change the design of a packaging structure can increase the efficiency of packaging materials.
Choice of materials
The materials used in flexible packaging structures play a key role in determining the sortability and recyclability of the packaging. This includes influencing how flexible packaging is identified and how it is disposed of by consumers. Packaging made from a single material is currently preferred as these structures are easier to recycle and contribute to improved quality and therefore value of the recyclate produced.
If PET is used in a PE, PP or mixed PO laminate, it should ideally be on the outer surface of the packaging structure so that it can be identified and removed by optical NIR sorting (during the recycling process). If the PET is in a middle layer of a PE or PP laminate, it can be sorted out by the density separation process (depending on the ratio of PET to PE, PP or mixed PO material).
PVC is a plastic that is problematic when used in packaging, as there is no infrastructure for PVC packaging in Europe. In addition, PVC can contaminate other types of plastic that could otherwise be recycled, making it less recyclable.
Biodegradable and compostable polymers
Biodegradable and compostable polymers, even in small quantities, are likely to interfere with mechanical PE, PP and mixed PO recycling processes and affect the quality and value of the final recyclate.
Size and shape:
The size, shape and construction of the packaging will determine how it behaves in a sorting facility. If individual packages (or removable parts of packages) are smaller than 20 x 20 mm, they are likely to fall through the holes in the sorting equipment used to sort packaging material. These end up in the residual fraction, which is usually sent for energy recovery (or still landfilled in some countries).
Printing inks and varnishes
Printing inks, although indispensable, have a negative impact on the final quality of the recyclate (unless they can be removed before the extrusion process) and are largely responsible for the grey-green colour of recycled PE and PP.