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Multilayering of conventional latex-based dispersion coatings containing small amounts of silica nanospheres: Runnability on a pilot scale flexographic coater and barrier performance, TAPPI Journal November 2023
ABSTRACT: The addition of functional coatings to packaging materials is a key requirement for increasing their performance and creating innovative packaging solutions. Flexography, a cost-effective printing method commonly used to print information and graphics directly onto a wide variety of packaging substrates, shows good potential for applying functional coatings. In this study, conventional clay-latex coating formulations containing approximately 1.3 wt% silica nanospheres were applied to a linerboard using a pilot scale flexographic printing web press. The performance of multilayered silica nanosphere-based coatings was compared with conventional coatings containing talc and/or wax dispersion in terms of coating grammage, runnability, and barrier performance. Coating grammage increased with an increased number of coating layers and a significant decrease in both the water vapor transmission rate (WVTR) and the direct water uptake of water (Cobb 120 wettability test) was observed for coatings containing silica nanoparticles. In general, the silica nanosphere-based coatings performed better than talc-based coatings. Talc/wax-based coatings had the highest variation in surface roughness due to an uneven distribution and variations of coating layers.
Journal articles
Magazine articles
Measurement and control of extensional viscosity in barrier coating dispersions, TAPPI Journal November 2023
ABSTRACT: This study aimed to understand the effect of various rheological additives on the extensional viscosity of barrier coating dispersions, as well as to understand the role extensional viscosity plays in stabilizing a liquid curtain. The apparent extensional viscosity was measured using two devices that create accelerating flows: a capillary viscometer and an orifice rheometer. Additives tested include several polyvinyl alcohols, a high molecular weight polyethylene oxide, and carboxymethylcellulose. Extensional viscosity plays a significant role in stabilizing a liquid curtain, as it slows down hole expansion and prevents impurities and disturbances from causing holes in the first place. Some of the additives could substantially increase the extensional viscosity of the dispersions without increasing the shear viscosity outside the typical range of processability for a curtain coater. Some of the additives exhibited coil-stretch transition, meaning they start increasing extensional viscosity above a certain extension rate. Polymers with low chain lengths exhibited finite extensibility, which indicates the polymer chain has fully extended and cannot provide further extensional viscosity, even though the extending force is increased. Polymeric additives with stiff or branched chains significantly raised shear viscosity without increasing extensional viscosity. Both methods could reliably measure extensional viscosity in curtain coating barrier dispersions.
Journal articles
Magazine articles
Managing the Decline of Graphic Paper Demand, Paper360º Nove
Managing the Decline of Graphic Paper Demand, Paper360º November/December 2017
Journal articles
Magazine articles
An Ode to Small, Paper360º May/June 2017
An Ode to Small, Paper360º May/June 2017
Journal articles
Magazine articles
Specialty Paper Trends, Paper360º September/October 2017
Specialty Paper Trends, Paper360º September/October 2017
Journal articles
Magazine articles
Pulp in a Frenzy, Paper360º, January/February 2018
Pulp in a Frenzy, Paper360º, January/February 2018
Journal articles
Magazine articles
PIMA, Paper360° Co-Host Executive Panel, Paper360º March/Apr
PIMA, Paper360° Co-Host Executive Panel, Paper360º March/April 2018
Journal articles
Magazine articles
RISI’s 2018 European CEO of the Year, Paper360º March/April
RISI’s 2018 European CEO of the Year, Paper360º March/April 2018
Journal articles
Magazine articles
2019 TAPPI/PIMA Awards: Saluting Our Industry Leaders, Paper360 May/June 2019
2019 TAPPI/PIMA Awards: Saluting Our Industry Leaders, Paper360 May/June 2019
Journal articles
Magazine articles
RISI’s Top 50 Power List, Paper360º, July/August 2017
RISI’s Top 50 Power List, Paper360º, July/August 2017