Received: 12 September 2023 Revised: 7 November 2023 Accepted: 13 November 2023 DOI: 10.1002/pts.2784
RESEARCH ARTICLE
Barrier, converting, and tray-forming properties of paperboard packaging materials coated with waterborne dispersions
Andrea Marinelli 1 Barbara Del Curto 1
| Johanna Lyytikäinen 2
| Panu Tanninen 2
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| Ville Leminen 2
1 Department of Chemistry, Materials and Chemical Engineering “ Giulio Natta ” , Politecnico di Milano, Milan, Italy 2 Lappeenranta-Lahti University of Technology LUT, Lappeenranta, Finland Correspondence Andrea Marinelli, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20131, Italy. Email: andrea.marinelli@polimi.it
Abstract In this work, different food-contact experimental and commercial aqueous polymeric dispersions were applied to paperboard via rod coating technology to achieve <5% non-cellulosic content. Barrier (water, moisture and grease), mechanical (tensile and bending) and converting (heat-sealing and creasing) properties were analysed before tray formation trials on pilot-scale equipment. Dispersion-coated samples were com- pared against polyethylene terephthalate (PET) extrusion-coated paperboard, the principal industrial material used for food trays. Results show that, within the investi- gated properties, waterborne dispersions can achieve similar barrier properties com- pared with PET, yet at lower dry coat grammage (12 g/m 2 vs. 40 g/m 2 of PET-coated paperboard). Additionally, the investigated coatings heat-sealed at temperatures as low as 80 – 90 C, almost 100 C less than PET; however, lower seal forces could be achieved (15 – 20 N/(25 mm) vs. 23 N/(25 mm) of PET-coated paperboard). Paper- board delamination occurred at the highest seal forces. Dispersion-coated trays were obtained at 4.5 – 5.0% blank moisture content. Formed trays at industrial processing parameters showed critical coating damage during converting due to tensile stresses. This work shows that milder processing conditions allow a reduction in coat defects.
KEYWORDS aqueous dispersions, barrier properties, coating, converting, food packaging, mechanical properties, paperboard trays
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INTRODUCTION
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recycling yields 2,3 . Indeed, previous studies 4 – 6 reported how DCs can be recycled, showing lower reject fractions. However, it was only recently that testing methodologies were standardized or developed for a European harmonization 7,8 ; besides, such recycling methodolo- gies are constantly adapting to address issues linked to the new pack- aging sold on the market. By potentially avoiding slot screening during recycling, thin coating and filler fragments might reach the secondary raw material (i.e., recycled material) or add up in the water circuits at the paper mill 9 . Related to microplastics, this potential issue is currently under discussion, possibly hindering the application of
Dispersion coating (DC) is an interesting technology that, despite being known for some decades, has only recently gained increased interest from the industry. Most of the commercialized coated fibre-based packaging is extrusion-coated or laminated. Only a few products are currently dispersion-coated 1 . One advantage of the DC technology is that it can achieve a lower final dry coat grammage compared with extrusion coating and lamination, reducing the non- cellulosic content of the packaging. This might lead to higher fibre
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2023 The Authors. Packaging Technology and Science published by John Wiley & Sons Ltd.
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Packag Technol Sci. 2024;37:149 – 165.
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