Lightweighting Plastic Packaging and Recyclability Dr Michael Scriba, CEO mtm plastics, Niedergebra (Germany)

It is more or less common knowledge that in lightweight design fully functional mono-materials are replaced by multilayers with one or two polymers different from the main material partly replacing mono-material and, with better barrier properties in thinner layers, reducing the overall weight of a pack. Consequently fully functional rigid packagings (bottles) are reduced in weight to a considerable degree. They will even become flexible packs (pouches), and films are reduced in thickness etc.

without losses in functionality. Lightweighting as a concept is enormously widespread and has considerably reduced the amount of virgin plastics used in packaging over the last decades. But there is a downside to this: Packers and fillers like to call this aspect resource efficient and use it as an excuse when it come to recyclability. The worldwide trend is evident but causes a lot of problems for sorters and recyclers: In state-of-the–art optical sorting factories (MRFs, PRFs) multilayer materials create random sorting results as the light beam will possibly penetrate one or two outer layers before it is reflected to be analyzed by the machine. The same is true in ballistic sorting because the ballistic properties of a flake become the more random the lighter it is, and in density separation altered specific weight of a formerly monopolymer results in bad yields. If a mulitlayer strucuture (randomly) ends up in the targeted polymer stream in recycling, its non-targeted components or polymers will always contaminate the recycled product. Reduced mechanical properties, discolouring, odours etc. etc. will have a negative impact on prices and the product will have difficulties to meet the high standards of plastic converters for their recycled feedstock. Something we often forget to mention: These effects are worsened by the ties needed to combine different layers. What I would like to challenge today is the argument that this deplorable situation is formally justified by the waste hierarchy „Reduce, Reuse, Recycle". There seems to be a common – and possibly wrong – understanding amongst packers and fillers that reducing the weight of a package is so resource-efficient that its recyclability can be neglected, and only so because „reducing" is located on a higher level than „recycling". Hence weight reduction seems to have become an end in itself. But is this correct? Reducing at the cost of recyclability means that

you save resources once, and once only. A recycled package can do so on and on again in every loop it enters into. We think that as so often there is no black and white in this. What we see is a classic conflict of targets that can only be solved by thorough analysis, which in this case have to be comprehensive Life Cycle Analyses. The LCAs then have to take into account the repeated resource efficiency of recycled polymers, and as happened in several cases not just compare lightweight packs to their heavier predecessors or ending the considerations after just one recycling step. We have to bear in mind that resource efficiency is just one aspect of eco-efficiency. In addition to that we recyclers for a reason should even pledge for a level playing field for reducing and recycling (if we want to stick with a hierarchic view at all): A package evidently designed to be recycled and having full functionality will much easier end up in a collection system than one that comes with the excuse „Sorry, I am not recyclable, but I am fully functional, in me your minced meat will stay fresh for twelve weeks". And every package collected and recycled will not end up in the environment. Collecting unrecyclable packs in a collection system only to incinerate or landfill them afterwards is no option either because in the eyes of the consumer this will compromise any recycling scheme: Why should I collect separately if a large proportion of what is collected will be disposed of anyhow. In conclusion we probably will have to accept the following facts:

1. Lightweighting is no end in itself although in contributes to the overall resource efficiency if the packaging value chain.

2. Lightweighting, functionality and recyclability of a package are three different targets in packaging design.

3. Functionality as in e.g. shelf life is not a result of lightweighting. Lightweighting can just keep up with heavier packaging as to functionality.

4. Conflicts of targets (reducing vs. recycling) can not be solved by merely referring to the order these targets are listed in the waste hierarchy.

5. The decision has to be made based on a comprehensive LCA that takes the resource efficiency of recycling in several loops into account.

6. Lightweight packaging has to be optimized as to recyclability as well. Otherwise it will compromise separate collection.

7. Resource efficiency is just one aspect of eco-efficiency. 8. It is recycling of flexible packagings too, that will really contribute

to waste free oceans. (May, 2016)