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  1. Kemira
6 December 2021

Repulpable Barrier Coatings Enable the Development of Recyclable Packaging

The repulpability of barrier coatings is the key to fibre-based packaging material recyclability and effective, circular material reuse. Kemira’s new dispersion barrier chemistry, Fennoguard™ GO, provides the perfect answer for FMCG companies seeking to find sustainable packaging alternatives.

Brand owners, fast-moving consumer goods (FMCG) companies, and retailers continue to be under intense pressure to find sustainable and safe packaging alternatives. Even more so now as the goals set previously for phasing out plastics and introducing fully renewable or recyclable packaging alternatives begin to draw closer.

Fibre-based packaging materials have gained much interest in the packaging value chain due to their excellent recycling properties. This has put barrier solutions in the limelight as they provide paper and board with much-needed functional properties to protect the packaged good from the environment and vice versa. The challenge with the often-used solutions, such as PE extrusion coatings and laminated structures, is that they take away from the renewable nature of paper and board and make for poor end-product recyclability.

Kemira’s new barrier chemistry, FennoGuard™ GO, answers the packaging material producer’s demand. The water-based dispersion barrier coating helps replace traditional plastic films and fluorochemicals used for protection against grease, oil, and other substances in fibre-based packaging. In addition, FennoGuard™ GO has excellent repulping properties, which enables the development of truly circular and recyclable packaging alternatives.

More efficient material reuse

Repulping properties are at the heart of fibre-based packaging recyclability and efficient material reuse. To ensure material efficiency, the barrier coating should break down easily in the repulping process and the amount of fibres, fillers, and other raw materials that get rejected from the process as waste should be minimized.
Kemira studied five different barrier-coated packaging boards to deepen the understanding of how they behave in the repulping process of an in-machine broke system. The barrier coatings studied were commercially available dispersion barrier coatings that included Kemira’s FennoGuard™ GO.

Based on the results, FennoGuard™ GO dispersion barrier coating can be easily repulped and in addition, the repulped material has a low reject rate – in the two studied sample boards, the reject percentage were as low as 0% and 1.7%. The other dispersion barrier coatings studied, proved to be more difficult to repulp. They had reject rates as high as 8.2% and 14.1%. When the repulping was chemically enhanced, the amount of reject could be considerably reduced.

[The repulpability of barrier coated boards is highly dependent on the chemistries and components used. The study proved that chemically assisted repulping can significantly reduce reject rates.]

High-performance wastewater treatment

A common concern related to the repulping of barrier-coated boards is that contaminants such as the hydrophobic particles originating from the coating would end up in the process wastewater or, worse still, be discharged in environment.

Our study shows that up to 80–85% of the hydrophobic particles in the coated broke could be attached back onto the fibres with a fixative in the board making process, thus enabling efficient recirculation of the repulped material. What’s more, chemically enhanced wastewater treatment helped to remove the majority of the remaining particles. As a result, up to 95–98% of all the hydrophobic particles in the process could be removed and efficiently managed.

A holistic approach is the key

The repulpability of barrier-coated packaging material is highly dependent on the dispersion barrier chemistries and components used. Base sheet properties also play a key role. For example, wet strength agents used in the base paper can have a negative effect on repulpability.

Based on our findings, efficient and sustainable repulping and recirculation of repulped broke, and thus, recycling of dispersion barrier coated materials, can be carried out in the current paper and board making processes. A holistic end-to-end understanding of the papermaking process and efficient chemical solutions are crucial already in the creation of optimized dispersion barrier coating in packaging board. They are also highly valuable for ensuring sustainable processes in all necessary production phases for circulating and reusing barrier coated boards.

This article is taken from a recent study titled “Dispersion barrier coated fibre-based materials and holistic study about repulping”. This was first presented at the 30th PTS Coating Symposium in September 2021.

On Wednesday, December 8, Kemira hosts a free industry webinar answering some of the key questions around the topic. The webinar will be available on-demand after the live session.

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