S E P A R A B I L I T Y

Over the last decades, the end life of packaging has become a major concern for companies commercialising bottles products, beyond the regulatory requirements in force since the 1990s. In reply to the increasingly obvious urgent need to take action to protect the environment companies have necessarily integrated sustainable development in their industrial strategies with the adaptation of products that that implies. This must be seen as opening new opportunities for the industry.
 

This involves widening the vision of packaging designers to take into account in particular the technical constraints of material recycling. Although expert advice in eco-conception is available for some 20 years the problems of effective recyclability/recycling of packaging reveal underlying complexity that must be understood to create articles that are attractive for the end-user and also compliant with the principles of the circular economy.
 
The Cetie enables the different actors of the packaging value chain to meet and work together to produce technical reference documentation. This chain thus now extends to actors dealing with end-of-life and material recycling. In reply to requests from members, a new working group in this context has been initiated with a first meeting held on the 10th April.
 
The scope of this working group in the first instance is the interaction between self-adhesive labels and glass recycling. This follows a previous action by Cetie between 2011 and 2015 to organise a working group under the auspices of the French packaging recycling organisation Citeo (formerly EcoEmballages) to improve the compatibility of certain self-adhesive labels with glass recycling.
 
These were labels on a transparent polypropylene base which were tear-resistant and strongly stuck to the glass. It had been observed that these labels maintained together with the glass fragments on crushing which interfered with the efficiency of the sorting process of recovered glass packaging and preparation for introduction into the glass furnaces. The work of this group led to a successful outcome (see L & C 379). An adhesive was identified which fulfilled all the required functions including that of losing adhesiveness in the recycled glass treatment process. This solution is in industrial use since then and gives entire satisfaction.
 
Although the context was more restricted than that of usual Cetie working groups the principle was as always to bring together companies from the thus extended value chain through to recycling. It was a particularly good example since the label producers present had never previously had the opportunity to gain knowledge of the problems of glass recycling. Their work in common was thus fruitful after, it must be admitted, a phase of mutual apprenticeship of the technical possibilities in the different fields of competency concerned.
 
This lack of prior contacts was indeed understandable because glass recycling has always been tolerant to the presence of paper label residues and at that time the label producers or designers had no reason to suspect that a change in the type of label might affect glass recycling. In this case, the global effects observed were limited as the proportion of this type of label in the glass collected was relatively low, but the effects were visible and measurable. The action was thus both to reply to the request of the brand concerned in line with their sustainable development objectives and to avoid more significant effects if these labels were adopted more massively by the markets.
 

The new Cetie group has fixed a first objective to add an « end of life » chapter to the existing guide « Pressure sensitive labelling of glass bottles and jars », based on the feedback from the previous development. It was further observed that the end of life should now be taken into consideration in all the Cetie guides concerning assembling different components of a package. From the exchanges, it was however concluded that the compatibility of a label adhesive with glass recycling could not readily be summarised as recommendations for limit values to respect for selected physical parameters. The previous work had required developing a test simulating in the laboratory the separability of labels in the recovered glass sorting process and verifying that this was pertinent for the beer bottles concerned. Though this remains a potentially useful tool for comparisons it cannot in the current state of knowledge be used as a discriminating test.
 
The most important message to communicate already to the industry is that the adhesives used for labels can have an impact on the efficiency of glass recycling and that solutions exist or can be developed to improve separability. More generally the compatibility of packaging components with material recycling cannot in many cases be summarised just as « good » or « bad » as extraneous materials may be tolerated within certain limits. However, the appropriate separability of all package components will always be a useful contribution to optimising the efficiency of recycling and maximising the environmental benefit.
 
This implies that the other actors of the value chain have access to the necessary technical information on the recycling process, particularly concerning the conditions enabling separation and the effects of residual foreign matter on glass melting. Another objective of the working group is thus to produce documentation clarifying the principles of sorting and the appropriate details of the production of glass packaging. The use of such information would of course not be limited to labels and it is indeed foreseen to extend the scope of the working group to all the components of products bottled in glass packaging.