Cellulose products for paperboard barrier coatings

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Kemian tekniikan korkeakoulu | Master's thesis
Fibre and Polymer Engineering
Degree programme
Master's Programme in Chemical, Biochemical and Materials Engineering
67 + 8
Traditional barrier coatings for paperboard food packaging are made of fossil fuel-based components. This decreases the sustainability and recyclability of the packaging. Cellulose is a renewable element of plants which has been studied for its coatability and barrier properties. When mechanically and/or chemically broken down into microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC), or cellulose nanocrystals (CNC), the material can be made into a water-based barrier coating with strong oxygen and grease resistant properties due to its high density and hydrogen bonding network. These cellulose products are safe for food contact, sustainable, recyclable, and can meet some of the requirements of food packaging barriers. Six cellulose products, three MFCs, two NFCs, and a CNC product, were studied through experiments designed to characterize the cellulose products and evaluate their properties as barrier coatings on folding boxboard. The cellulose products were coated onto the folding boxboard substrate with a laboratory rod coater with single and double layers. The coat weight, optical topography, water vapor transmission rate, and oil and grease resistance were analyzed along with stereomicroscope and scanning electron microscope imaging of the surface and cross sections of the coated samples. The target was to compare the cellulose products and determine which products are most feasible as barrier coatings. The cellulose products adhered well to the folding boxboard, however, coating defects such as craters and crazing were seen on the surface. The barrier results showed strong grease resistance among most of the cellulose products. The water vapor transmission rate was too high to provide an adequate barrier for food packaging; a common result seen with cellulose products due to their hydrophilicity. The CNC product gave the best results overall and was recommended for continued studies.
Paltakari, Jouni
Thesis advisor
Saari, Terhi
Talja, Riku
barrier, cellulose, dispersion coating, food packaging, paperboard
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