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Three Benefits of NIR Technology, Paper360º September/October 2022

TAPPI Journal Summaries, Paper360º September/October 2022

TAPPI Journal Summaries, Paper360º September/October 2022

Comparative study of guar gum and its cationic derivatives as pre-flocculating polymers for PCC fillers in papermaking applications, TAPPI Journal April 2022

ABSTRACT: In this work, gums from guar seeds were evaluated as a potential precipitated calcium carbonate (PCC) filler pre-flocculant to induce functional filler in papermaking applications. In recent years, guar has been conidered one of the promising wet-end additives due to its abundance, rich source of hemicellulose content, and bio-degradability. However, application of guar gum in filler pretreatment methods for producing high ash paper has scarcely been reported. In this paper, the flocculating ability of three types of guar gum was established with charge analysis and turbidity (NTU) of the system at 1% and 5% for each gum: native gum (NG) having a degree of substitution (DS) of 0, and cationic gums having a DS value of 0.07 (CL) and 0.15 (CH). It was interesting to observe that even at a 5% dose of G, the charge density of PCC did not deviate much from the initial values. The system carried a weak negativeharge, resulting in an unstable colloidal suspension that led to PCC-PCC particle bridging. On the other hand, the operative mechanism of CL and CH during adsorption and PCC flocculation was predicted to be charge neutralization and electrostatic-patch formation, accompanied by particle bridging. Note that CL, with a maximum 47.5% eduction in residual turbidity of PCC at a 1% dose, was much more efficient in doing so than the other two gums; NG had a 40% maximum reduction in residual turbidity at a 5% dose and CH had a maximum 30% reduction at a 1% ose. Later on, floc formation and structure were correlated with optical and field emission scanning electron microscopy (FE-SEM) images. In the next set of trials, paper properties were determined by varying the different gum dosages from 0.2% to 5% at a constant dose of 20% filler. It is also noteworthy to mention that with 1% CL (low DS) dose, PCC retention increased by 39%, which also enhanced the tensile, tear, burst, and opacity properties by 11%, 19%, 5%, and 4.4%, respectively, without significantly affecting the bulk properties. Further, wide-angle X-ray diffraction (XRD) analysis nd Fourier transform infrared (FTIR) analysis revealed that pre-flocculating PCC with a 1% gum dose did not induce any change in crystalline transformation. Based on observation, it was found that cationic gums with low DS values re a better choice for maximizing the strength of paper while maintaining bulk and high opacity when pre-flocculaion is adopted to increase the filler retention in paper.

The Creep Properties of Paper, TAPPI Journal August 2022

ABSTRACT: The creep proprties of alpha-pup handshetts were determined at various constant tensile loads and relative humidities for the purpose of clarifying the prerupture mechanical behavior of paper.

Meeting the Future Through Knowledge Sharing and Connection, Paper360º March/April 2023

TAPPI Journal Summaries, Paper360º March/April 2023

TAPPI Journal Summaries, Paper360º March/April 2023

Small Jobs in Maintenance, Paper360º March/April 2023

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.

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.

Multifunctional barrier coating systems created by multilayer curtain coating, TAPPI Journal November 2023

ABSTRACT: Functional coatings are applied to paper and paperboard substrates to provide resistance, or a barrier, against media such as oil and grease, water, water vapor, and oxygen, for applications such as food packaging, food service, and other non-food packaging. Today, there is increasing interest in developing recyclable and more sustainable approaches for producing these types of packages. This paper focuses on water-based barrier coatings (WBBC) for oil and grease resistance (OGR), water, moisture vapor transmission rate (MVTR), and oxygen barrier performance. The main goal is to create coated systems that can achieve more than one barrier property using multilayer curtain coating (MLCC) in a single application step. One advantage is in optimizing coating material cost with the use of functional chemistry in confined layers where performance is balanced within the coating layered structure. This allows simultaneous application of layers of different polymer types in one step to achieve the appropriate performance needs for a given barrier application. This paper provides working examples of using MLCC to create coating structures with multiple barrier properties in a single application pass. Barrier polymers studied include styrene butadiene, styrene acrylate, starch-containing emulsions, and polyvinyl alcohol. The paper also shows the effect of increasing the pigment volume concentration with platy clay or fine ground calcium carbonate on MVTR and OGR barrier properties.