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Journal articles
A method to produce paperboard with a lightweight low-density coating, TAPPI Journal November 2025
ABSTRACT: In this work, a method is described in which a coating layer is produced that consists of a network of bubble-shaped air-filled voids within the coating. This is accomplished by instantaneously flash-drying all the water in the coating as it exits the application nip. The nip is formed between a polished chrome drum and a deformable press roll. The combination of the drum temperature, nip pressure, and nip width allow for sufficient energy to be transferred to the coating to completely flash-dry the coating material. The pressure within the nip is sufficient to allow the coating to superheat within the nip, then flash boil as it exits the nip. This boiling effect and resulting expansion are constrained by the roll surface, resulting in a coated surface that mirrors the polished chrome surface. The coating immobilizes while in the process of boiling, which preserves the bubble structure. With a coat weight of 5 g/m2, a flat, smooth surface is produced. This process was scaled up to a mill production machine layout and run at speeds as high as 450 m/min.
Journal articles
Estimating dose and interaction of X-rays with cellulose-based fibrous materials using micro-computed tomography, TAPPI Journal March 2026
ABSTRACT: Micro-computed tomography (ìCT) has a reputation as a nondestructive analysis method. Unfortunately, this leads to the common misconception that radiation damage of the sample does not play a role. With the increased use of ìCT in laboratory-based machines, more and more cellulose-based materials are studied. In this paper, we show with three examples that radiation damage is important in dry and wet paper and in viscose fibers. In an attempt to quantify radiation damage, we came up with a workflow that enables researchers to predict the X-ray dose within a laboratory-based ìCT machine. This gives researchers the possibility to quantitatively judge the influence of radiation damage on each measured sample. While one cannot extend the measured doses from one machine to another, one can still apply the work flow presented in this study to any ìCT setup. In this way, it is possible to minimize radiation damage by choosing the best parameters in a ìCT for obtaining perfect data with no or little radiation damage.
Journal articles
Magazine articles
New opportunities in the paper and nonwovens industries with foam-assisted web forming and chemical application, TAPPI Journal January 2023
ABSTRACT: Foam-assisted web forming and chemical application technologies have great potential to improve manufacturing efficiency and product quality in the paper and nonwovens industries. In this study, the benefits of foam forming and foam-assisted application of chemicals were demonstrated in a pilot machine trial. Uniform high-bulk webs of unrefined bleached softwood kraft pulp (BSKP) and viscose fibers were manufactured by foam forming. It was shown that foam formed low-grammage and high-bulk viscose fiber webs can be strengthened by foam-assisted application of latex onto the wet web. Correspondingly, foam-assisted application of carboxymethyl cellulose (CMC) and anionic polyacrylamide (A-PAM) improved the strength of the foam formed low-grammage and high-bulk BSKP web. Overall, the pilot machine results indicated that material cost savings could be achieved and a high-performance product could be manufactured with foam-based technologies.
Journal articles
Magazine articles
Water chemistry challenges in pulping and papermaking • fundamentals and practical insights: Part 2: Conductivity, charge, and hardness, TAPPI Journal June 2023
ABSTRACT: Although water is essential to the papermaking process, papermakers often overlook its importance and focus on fibers, fillers, and chemical additives. A better understanding of water properties and chemical interactions associated with water at the wet end leads to a sound foundation for high-quality paper production and smooth operation. Water is an excellent solvent for ionic substances, both organic and inorganic. These substances contribute to system conductivity, charge, and hardness and significantly impact the papermaking process. Part 1 of this paper, published in TAPPI J. 21(6): 313(2022), discussed fundamental water properties, water chemistry, and the impact of pH on pulping and papermaking operations. In this paper, we review definitions, sources, and the typical symptoms of the effect of conductivity, charge, and hardness on the productivity of the papermaking process. Sources of conductivity, charge, and hardness impacting these factors, measurement methods, and available correction strategies for their control are also discussed.
Journal articles
Magazine articles
Multiple recycling of paperboard: Paperboard characteristics and maximum number of recycling cycles— Part I: Multiple recycling of corrugated base paper, TAPPI Journal November 2019
ABSTRACT: Paper for recycling is an important fiber source for the production of corrugated base paper. The change in production capacity toward more and more packaging papers affects the composition of paper for recy-cling and influences the paper quality. This research project investigated the influence of the multiple recycling of five different corrugated base papers (kraftliner, neutral sulfite semichemical [NSSC] fluting, corrugating medium, testliner 2, and testliner 3) on suspen-sion and strength properties under laboratory conditions. The corrugated board base papers were repulped in a low consistency pulper and processed into Rapid-Köthen laboratory sheets. The sheets were then recycled up to 15 times in the same process. In each cycle, the suspension and the paper properties were recorded. In particular, the focus was on corrugated board-specific parameters, such as short-span compression test, ring crush test, corrugat-ing medium test, and burst. The study results indicate how multiple recycling under laboratory conditions affects fiber and paper properties.
Journal articles
Magazine articles
Orifice geometry as a tool for evaluating extensional flow resistance of barrier coating colors, TAPPI Journal November 2024
ABSTRACT: Knowledge of extensional flow behavior of coating colors can be beneficial for improving runnability and eliminating defects in various coating processes. The current work evaluates the use of an orifice geometry attached to a commercial capillary viscometer as a tool to obtain extensional flow properties of barrier coating dispersions. By measuring the pressure drop across the orifice as a function of flow velocity, the method presents the flow resistance as Euler number at industrially relevant high deformation rates. The results agree with the earlier results obtained with a capillary entrance pressure loss technique. The type of polymer additive is shown to control the extensional flow resistance, with high molecular weight linear flexible polymers such as polyethylene oxide (PEO) and polyvinyl alcohol (PVOH) having highest impact. The orifice method offers advantages over other approaches, including the need for only a small sample amount, ease of measurement, and access to high deformation rates.
Journal articles
Magazine articles
Dynamic compression characteristics of fiber-reinforced shoe press belts, TAPPI Journal April 2025
ABSTRACT: Shoe press belts contribute significantly to the overall dewatering performance in the press section of a paper machine. Within the shoe press nip, the press belt faces a dynamic and multidimensional load that mainly leads to a compression of the structure. As this will cause a loss in void volume, knowledge of the dynamic compression characteristics of shoe press belts is crucial for optimized dewatering. A novel method was developed to examine the dynamic compression characteristics of grooved polyurethane press belts. Therefore, an experimental setup allowing realistic boundary conditions to test specimens was placed in a servo-hydraulic testing machine. Press belt specimens with different matrix material formulations and groove patterns were tested under varying load rates equivalent to different paper machine operational speeds. The results showed an evident sensitivity of the dynamic compression stiffness to the operational speed of the paper machine. This behavior was seen to be more sensitive to changes in the matrix material formulation than to adaptions of the groove pattern. As a result, the compression of the press belt within a shoe press nip is not only influenced by the peak pressure within the shoe press nip but also depends on the operational speed of the paper machine.
Journal articles
Editorial: The emergence of AI in additives development, TAPPI Journal March 2025
ABSTRACT: The continuing evolution of artificial intelligence (AI) and its penetration into the core of the world of papermaking were undeniable at TAPPICon 2024 and especially within the content presented and sponsored by TAPPI’s Papermaking Additives Committee. On one side of the spectrum, there were traditional methods of chemical development and application grounded in natural intelligence, while on the other, there was the emerging presence of algorithmic decision-making and machine learning within the development cycle. The latter technology is brimming with the kind of promise that could reshape how additives are conceived, developed, and applied, turning what was once a matter of trial and error into something far more precise and previously out of reach.
Journal articles
Using multi-method analysis to identify challenging paper machine deposits and defects, TAPPI Journal March 2025
ABSTRACT: Based on its speed and versatility, Fourier transform infrared (FTIR) spectroscopy is the industry’s common starting point for analysis of a paper machine deposit or defect sample. However, certain contaminants and papermaking process additives cannot be precisely identified solely by infrared spectral interpretation. This lack of specificity could lead to a misinterpretation of the composition of the deposit or defect. A multi-method analysis uses data from two or more analytical techniques, including FTIR spectroscopy, microbiological staining/phase contrast microscopy, pyrolysis-gas chromatography/mass spectrometry (Pyro-GC/MS), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), to produce a more specific assessment of a sample’s composition. This paper discusses the use of a multi-method analysis in deposit and defect analysis and presents several case studies that demonstrate how this comprehensive approach can often produce an interpretation result of greater conviction and value to the papermaker.
Journal articles
Research on an energy model for X-ray measurement of paper ash content using COMSOL, TAPPI Journal May 2025
ABSTRACT: Ash content is one of the critical quality parameters in papermaking production. Traditional 55Fe radioactive sources used for online ash content measurement have a short lifespan and high costs, while offline methods such as the combustion method or chemical analysis are time-consuming. Using an X-ray tube as the radiation source, continuous X-ray measurement offers advantages such as being rapid, non-destructive, and cost-effective. In this study, COMSOL software was employed to simulate the measurement process and establish an energy attenuation model for X-ray measurement of paper ash content. The model simulates the energy attenuation of X-rays before and after transmission through four materials: calcium carbonate (CaCO3), titanium dioxide (TiO2), wood-based plant fibers, and paper samples filled with CaCO3. The absorption coefficients of paper samples with varying ash content were investigated using the model and compared with experimental results obtained from continuous X-ray measurements. The results indicate that the proposed energy simulation model can reduce the measurement error of paper ash content by 1%, significantly enhancing the reliability and accuracy of ash content measurement.