More Circularity

Creating more sustainable packaging is a core objective for many players in the cosmetic industry. To achieve this target, a variety of solutions can be applied, all of them driven by the aim to reduce the amount of virgin fossil-based raw materials. The replacement of virgin polymers through increased usage of recycled polymers in packaging production is consequently one of the targets for example of many Fast Moving Consumer Goods (FMCG) businesses.

A remaining challenge in using recycled polymers, especially in large quantities, is the insufficient avail-ability of high-quality recycled polymers. In many cases, the available material not only shows a varying quality in terms of polymer characteristics, impurities, and odour, but also in terms of colour, resulting in an inconsistent packaging appearance and making it difficult to meet the high expectations of cosmetic consumers.

For this reason, four partners1 initiated the “Design4Circularity” (D4C) project with the idea of developing a packaging structure that, on the one hand, meets the requirements of cosmetic packaging in terms of appearance, and on the other hand, is designed to create a cleaner waste stream, and a circular packaging life cycle. The aim of this project is to motivate peers to follow this example to achieve a measurable impact on the market.

To successfully develop such a new packaging structure, it is necessary to consider the entire life cycle of the package when creating a new design. This includes polymer production, polymer additivation, printing and design, and last but not least, sorting and recycling. Whilst  the goals could be achieved in successive development phases, the project partners were convinced that a joint development, considering all the system implications during the development phase, would create a better solution more efficiently and faster. Therefore, they joined forces, to bring all the required expertise to the table and jointly develop a circular cosmetic packaging solution which is designed to create a cleaner waste stream and pave the way towards more sustainable packaging. The solution is meant to be a blueprint for the rest of the industry, enabling a fast adoption and scale up.

Fully body sleeved bottle

Current standard packaging for cosmetics consists of a coloured bottle made of plastic (HDPE, PET), a closure made of PP material, and adhesive labels for decoration purposes. 

However, when it comes to meeting the requirements for circularity, this packaging structure brings some challenges, as the project team discovered. One challenge is that inks and adhesive on the labels contaminate the recycling material. Another challenge is the colourant (Masterbatch) used, which accumulates in the recycled material, reducing the value of the final recyclate and further limiting its possible applications.

To avoid all this, the core of the new packaging design is based on an uncoloured HDPE bottle, containing 100% recycled polymers and the right additivation. To create the necessary cosmetic appeal, the bottle is fully covered with a full body sleeve, which can be printed according to the relevant needs. 

After disposal, the bottle can be detected as an HDPE bottle in standard sorting facilities, and the HDPE will be separated from the sleeve material in the subsequent recycling steps. The entire new packaging structure is designed for recycling in accordance with eco-modulation, a topic that has recently been in the spotlight. Simply put, eco-modulation is the differentiation of EPR (Extended Producer Responsibility) license fees based on the recyclability of a product.

The role of the recycled polymers

As the bottle makes up most of the material used for the cosmetic packaging, it is key to select the right recycled polymer to meet this industry’s demanding requirements. Using recycled polymers in the production of the packaging broadens the scope of the properties relevant to consider during material sourcing.

In particular, materials with reduced odour and impurities are required to fulfil the basic needs of a bottle produced from 100% recycled HDPE. The level of impurities and odour in recyclates significantly depends on the process and technology used in the mechanical recycling plant. In this project, high-quality HDPE recycled material (PCR) based on a special transformational recycling technology² was used, featuring low odour and low impurity levels.

How additives support circularity

Even though HDPE is one of the polymers whose recycling infrastructure is rapidly evolving, the focus of the project was on polymer behaviour during the recycling steps to achieve a sustainable circular plastics economy. It is known that HDPE can degrade during processing (or reprocessing). This leads to a reduction of the mechanical and durability properties of the original material or of the virgin material containing a significant loading of recyclate. For example, impact strength and/or ESCR (environmental stress cracking resistance) can be significantly affected, leading to a potential failure in use of the final articles, depending on the conditions used.

Another reason for potential lower quality of HDPE recyclate can be found in the limited effectiveness of stabilisation (and re-stabilisation) mostly used at first additivation of the virgin material and/or at subsequent recycling steps, typically during regranulation.

In fact, some of the required properties of 100% HDPE recyclate, or of HDPE virgin material containing high loading of recyclate, can-not always be achieved using traditional stabilisation which has been designed typically with just one-use-step in mind.

To solve this, it was investigated as how to specially designed additive solutions, which are not only applied to the virgin materials but also to each recycling step, can help to prevent unexpected degradation of properties in the finished parts.

Various additive solutions based on high performance stabilisation packages have been tested simulating multiple recycling steps to represent both actual bottle manufacturing and recycling conditions. Critical material properties indicating the extent of degradation (molecular weight distribution, melt flow rate and impact strength) were measured after each cycle and compared to the starting material. 

For the project, an additive package was designed³ especially targeting the polymer protection during recycling processes. The tests have shown that with the right additivation, stabilisation of the recyclate can be maintained at appropriate levels, a key step towards reusing recycled polymers in highly demanding applications like cosmetic applications and for achieving plastic circularity.

Printed sleeve

With a colourless body for the packaging, the brand messaging and required product information needs to be displayed on a sleeve. To achieve customer recognition, it was decided to choose a printed full body sleeve. Within the sorting facilities, printed sleeves are currently separated from the bottle material and usually are not used for high quality recycling.

For a full circular solution, the introduction of deinking of flexible materials in recycling plants has been anticipated by the project partners. Therefore, the ink system chosen for the development of the new packaging system includes deinking primers as a functional element of the sleeve enabling a recycling process, increasing the circularity of the packaging overall. The bottle/shrink sleeve combination is intended for removal at a materials recovery facility. This requires good sortability, a hot washing process, and further processing of the material. The inks are washed off enabling the material to be reprocessed into recyclate.

An additional challenge for the printing of the full body sleeve is to achieve differentiation of the packaging, which requires a far superior quality of ink. Mainly a strong opacity of the inks, in this case white, is required. In collaboration with a sleeve manufacturer4, the project team was able to provide ink systems that enabled the printing of a full body, coloured and appealing cosmetic sleeve that keeps the de-tection rate of the IR scanner in the sorting facilities and allows for potential deinking during the recycling step.

Beyond this, adhesion to various substrates, flexibility for the shrink process, a good scratch resistance and no ink transfer during the hot steam shrinking process were critical for suc-cess. The prevention of ink splitting, being PVC-free, and of course, com-pliance with NPH (Nutrition, Pharma and Hygiene) standards were additional essential factors for the selection of the adequate ink system.

(al)ready for recycling

Recyclability has been defined as a key step in the project, as this is one major argument in creating this circular cosmetic packaging solu-tion. It soon became clear that the various available recyclability guidelines on full body sleeved packaging contrasted with the project’s recyclability targets.

For this reason, the project conducted its own real sorting tests of the packaging solution at a German sorting facility. It should be noted that in the meantime, however, the German ‘Mindeststandard VerpackG 2022’ has since changed its position on transparent or light blue PET containers with full body sleeves. 

Advanced sorting technologies 

The project has shown how packaging design can be used to improve the quality of recycled polymers for circular usage. Improvements in packaging design, as well as process improvements, have been addressed. 

To achieve the ultimate goal of full circularity, necessary adoptions be-yond the reach of the project owners have been identified. Whereas the absence of label and adhesives already improves the waste stream, the goal of the project is to achieve sorting of the bottle into the colourless high value HDPE waste stream.

But to accomplish sorting of a bottle with printed full body sleeve into the colourless PE waste stream, further advancements in sorting technology, such as artificial intelligence or digital watermarking would be required to help reach such sustainability goals.

Conclusion

The identified packaging platform solution is made for circularity. It consists of a colourless bottle from recycled polymers, with full body sleeve, which is fully recyclable and creates a cleaner polymer waste stream. The full body sleeve is de-inkable and the additivation of the polymer can stabilise the recyclate at appropriate levels, when recycled multiple times. The overall aim of the developed solution is to become an industry standard.

References:

1 Borealis, Clariant, Beiersdorf and Siegwerk

2 Borealis’ Borcycle M

3 Addworks by Clariant

4 All4Labels