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Article

Lignin-Containing Coatings for Packaging Materials—Pilot Trials

1
Department of Engineering and Chemical Sciences, Karlstad University, SE-651 88 Karlstad, Sweden
2
RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy, Box 5604, SE-114 86 Stockholm, Sweden
3
Calamo AB, Box 6, SE-655 02 Molkom, Sweden
*
Author to whom correspondence should be addressed.
Academic Editors: Bruno Medronho and Magnus Norgren
Polymers 2021, 13(10), 1595; https://doi.org/10.3390/polym13101595
Received: 30 March 2021 / Revised: 10 May 2021 / Accepted: 12 May 2021 / Published: 15 May 2021
(This article belongs to the Special Issue Cellulose and Lignin Feedstock for Renewable Materials)
One severe weakness of most biopolymers, in terms of their use as packaging materials, is their relatively high solubility in water. The addition of kraft lignin to starch coating formulations has been shown to reduce the water solubility of starch in dry coatings. However, lignin may also migrate into aqueous solutions. For this paper, kraft lignin isolated using the LignoBoost process was used in order to examine the effect of pH level on the solubility of lignin with and without ammonium zirconium carbonate (AZC). Machine-glazed (MG) paper was coated in a pilot coating machine, with the moving substrate at high speed, and laboratory-coated samples were used as a reference when measuring defects (number of pinholes). Kraft lignin became soluble in water at lower pH levels when starch was added to the solution, due to the interactions between starch and lignin. This made it possible to lower the pH of the coating solutions, resulting in increased water stability of the dry samples; that is, the migration of lignin to the model liquids decreased when the pH of the coating solutions was reduced. No significant difference was observed in the water vapor transmission rate (WVTR) between high and low pH for the pilot-coated samples. The addition of AZC to the formulation reduced the migration of lignin from the coatings to the model liquids and led to an increase in the water contact angle, but also increased the number of pinholes in the pilot-coated samples. View Full-Text
Keywords: barrier coatings; glycerol; lignin; starch barrier coatings; glycerol; lignin; starch
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MDPI and ACS Style

Javed, A.; Rättö, P.; Järnström, L.; Ullsten, H. Lignin-Containing Coatings for Packaging Materials—Pilot Trials. Polymers 2021, 13, 1595. https://doi.org/10.3390/polym13101595

AMA Style

Javed A, Rättö P, Järnström L, Ullsten H. Lignin-Containing Coatings for Packaging Materials—Pilot Trials. Polymers. 2021; 13(10):1595. https://doi.org/10.3390/polym13101595

Chicago/Turabian Style

Javed, Asif, Peter Rättö, Lars Järnström, and Henrik Ullsten. 2021. "Lignin-Containing Coatings for Packaging Materials—Pilot Trials" Polymers 13, no. 10: 1595. https://doi.org/10.3390/polym13101595

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