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The winding mechanics of laminate webs, TAPPI Journal February 2020
ABSTRACT: Models that describe the residual stresses due to winding single-layer webs at the end of roll-to-roll manufacturing machines are mature. These models have been used to reduce or avoid defects that are due to winding. Many laminated products exist where two or more webs have been joined to form a thicker composite web. The properties of the web layers provide a unique functionality to the product being manufactured. No laminate winding models exist in the literature. This paper will focus on the development of a laminate winding model and laboratory test verification of the model.
Journal articles
Magazine articles
Root cause analysis of cationic polymer additive efficiency decline in virgin and recycle containerboard mills, TAPPI Journal January 2020
ABSTRACT: It is well known that retention, drainage and strength polymers struggle to perform (if at all) in virgin containerboard mills. In-depth studies have been undertaken in this area for more than seven years, investigating the issue from all directions. A key finding of this work is that soluble lignin is detrimental to chemical efficiency. A strong correlation exists between decreased chemical efficiency and high soluble lignin. Both recycled systems and virgin systems have been studied, and this correlation holds true regardless of furnish. The primary area of concern is virgin container-board, because these mills tend to have the highest lignin levels. Some highly closed recycled mills can also build elevated lignin levels that can negatively affect chemical efficiency.
Journal articles
Editorial: Fundamental understanding enables new coating opportunities, TAPPI Journal January 2025
TAPPI's Coating, Printing, and Surface Enhancement (CPSE) Division pursues open exchange of technical information related to materials, equipment, and processes for the manufacture, quality control, and use of coated papers, paperboard, and other substrates. Much of this technical information is presented at sponsored conferences, including TAPPICon and the Advanced Coating Symposium. Based on feedback from these events, TAPPI Journal peer reviews the research from these events that adds significant value to the scientific community. In last year's November issue, we presented five peer-reviewed manuscripts based on presentations given at TAPPICon 2024.
Journal articles
The influence of precoating layers on the performance of water-based barrier coatings, TAPPI Journal January 2025
Cellulose nanofibrils (CNF) on paper have been demonstrated to be an effective barrier against oxygen and grease and have been shown to improve the barrier performance of dispersion-based barrier coatings. The potential to produce paper grades that have good oxygen, grease, and moisture barrier properties is clear, but a better understanding of the synergies between CNF, other coating layers, and water-based barrier coatings (WBBC) is needed to optimize these systems. Different coat weights of a commercial WBBC were applied to papers that have a range of different qualities and thicknesses of CNF precoating layers. The same WBBC was also applied to pigmented coated paper, with various types of pigments and latex levels. Samples were characterized in terms of grease resistance, water vapor transmission rate (WVTR), and oxygen transmission rate (OTR) before and after folding. The results were contrasted to cases where the WBBC was applied to the paper with no precoating layer. When the WBBC is applied on a CNF layer or the pigmented coating layer, the performance of the WBBC for the water vapor barrier improves a significant amount compared to when the WBBC is applied to the base paper with no precoating layer. This improvement likely comes from these precoating layers filling in the large paper pores, which leads to the WBBC forming a continuous layer at low coat weights. Folding decreases the moisture barrier performance to some degree, but the grease resistance is not influenced by folding when a CNF precoating layer is involved. Oxygen barrier properties are moderate for the CNF layer alone and are less than 5 cm3/m2/day when WBBC is coated on the CNF layer. This result likely comes from the barrier coating’s ability to repair defects in the CNF layer to stop the easy passage of oxygen in defect regions of the sample.
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
Improved barrier performance with microfibrillated cellulose, TAPPI Journal March 2025
ABSTRACT: In this work, the impact of microfibrillated cellulose (MFC) on the properties of water-based barrier coatings intended for food packaging have been explored. Commercially available MFC was used for improving the rheology and water retention of three different commercially available dispersion coatings (acrylic, styrene acrylic, and polylactic acid). Coatings were applied by rod to paper, and barrier properties were tested by measuring air permeability and water barrier properties. Results clearly showed that addition of MFC to water-based dispersion coatings improved the barrier performance of the final coatings.
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
Application of AI-based approach to control the papermaking process, TAPPI Journal March 2025
ABSTRACT: This paper explores AI’s role in revolutionizing the pulp and paper industry, and specifically in predicting wet tensile strength (WTS) for specialty-grade papers. Leveraging eLIXA technology, a 90-day study achieved a 15% reduction in chemical dosage and an 80% decrease in wet tensile standard deviation. The real-time dosage prediction led to optimizing the wet strength resin (WSR) consumption and improved process reliability. The self-learning models exhibited adaptability to changing variables, ensuring their robustness. Overall, this study highlights AI’s transformative impact on efficiency, cost savings, and product quality within the dynamic landscape of papermaking. The approach used for wet strength optimization has been used to optimize other aspects of pulp and paper production.
Journal articles
Pilot-made, highly extensible paper for dry 3D forming, TAPPI Journal May 2025
Cellulose fiber-based packaging materials must perform well in demanding three dimensional (3D) forming process conditions. On the other hand, the development of manufacturing concepts is required for improved competitiveness of bio-based materials. This study covers some key factors that influence the extensibility of cellulose fiber-based structures and presents a pilot-scale development study of a 3D formable material concept. Bleached softwood kraft (BSK) pulp from a Nordic pulp mill was used in the pilot trials. Cellulose-based webs were formed using water-laid and foam-laid web forming using a pilot paper machine. For the water-laid forming, the BSK pulp was refined by applying a high consistency (HC) phase at over 40% consistency, followed by a low consistency (LC) refining at 4% consistency. The BSK pulp was refined for the foam-laid forming by only applying lowconsistency refining. In the foam-laid web forming, anionic sodium dodecyl sulfate (SDS), two foamable latexes, and polyvinyl alcohol (PVA) were used as foaming agents. The pilot rolls were dried at a separate steam cylinder dryer pilot and compacted in-plane in the machine direction (MD) at a separate pilot machine. Tensile properties of the treated paper webs were measured and evaluated with respect to achieved web shrinkage. The same dimensional contraction brought by shrinkage was almost strained out in tensile testing. The results indicated that the shrinkage that occurred by drying and in-plane compaction depended on the pulp furnish. The water-laid material achieved about 30% elongation, whereas the foam-laid material achieved significantly above 50% elongation. The 3D forming performance of the dry materials was tested using fixed and sliding blank methods. The dry paper sheets performed well enough in 3D forming for application to many consumer package applications according to their extensibility.
Journal articles
Paper strength factors in systems with nanofibrillated cellulose, cationic starch, colloidal silica, cationic acrylamide copolymer, and hydrodynamic shear, TAPPI Journal May 2025
ABSTRACT: Laboratory paper sheets were formed by first pretreating nanofibrillated cellulose (NFC) with cationic starch at the 5% level by mass. The treated NFC was then added to stock prepared from 100% recycled copy paper. The combined furnish was next optionally treated with a cationic retention aid (cPAM, 0.1%) and then colloidal silica (0.1% or 0.2%). Vacuum dewatering, fine-particle retention, and several paper properties were studied as a function of the colloidal silica level (zero, 1%, and 2%) and at different levels of shear stress applied just before forming the sheets. Dewatering and strength results were generally more favorable when using a medium charge cationic starch (~ 0.03 degree of substitution, DS) to pretreat the NFC rather than a high charge density cationic starch (~ 0.2 DS). In each case, the dewatering was further enhanced by subsequent treatments by cPAM (0.1% on whole furnish solids) and then even more with the final addition of colloidal silica (0.1% and 0.2% levels compared). However, the colloidal silica additions progressively hurt the tensile strength of the paper, especially in the case of the high charge cationic starch and at the higher level of colloidal silica. Though the dewatering performance was favorable, in such cases, the paper strength was not improved compared to paper made without any NFC. The fact that the systems involving cPAM treatment, and especially those involving both cPAM and colloidal silica, tended to reduce the resulting paper’s tensile strength supports a mechanism in which the additives result in the clustering of the NFC, possibly in multiparticle bunches. Evidence suggests that such bunches of clustered NFC particles, which are difficult to redisperse even at levels of hydrodynamic shear present in high-speed paper machine systems, are resistant to full integration into the sheet structure as the paper is being formed.