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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
Magazine articles
Study on the effect of aluminum diethyl phosphinate in synergy with ammonium polyphosphate on the flame retardancy of cellulose paper, TAPPI Journal April 2025
ABSTRACT: This paper involved the synergistic incorporation of ammonium polyphosphate (APP) and diethyl aluminum phosphinate (AlPi) as flame-retardant fillers for producing flame-retardant paper. The research revealed that APPs were square particles with a smooth surface, and their solubility was 0.29 g/100 mL at 20°C, which increased to 4.12 g/100 mL at 60°C. The surfaces of AlPis were rough and irregular. The solubility of AlPi was 0.023 g/100 mL at 20°C, and the solubility remained stable when the temperature increased. The addition of AlPi had a minor influence on the pulp beating degree. The tensile strength of kraft/APP/AlPi decreased with the increase of the AlPi addition. For a paper with 20 wt% APP and 0 wt% AlPi, the limiting oxygen index (LOI) value was 27.2%, and it burned completely at the eighth second during vertical combustion. When the AlPi additive content increased to 20 wt%, its LOI value increased to 32.2%, and the vertical combustion self-extinguished as soon as the flame was removed. Scanning electron microscopy (SEM) showed that the char residue of the kraft/APP/AlPi had a more complete fiber network structure than that of kraft/APP. The Raman spectroscopy indicated that the area ratio of the D (amorphous phase; disordered graphite vibration) band to the G (crystal phase; graphite carbon vibration) band (ID/ IG) ratio of kraft/APP/AlPi was lower than that of kraft/APP, meaning that the graphitization degree of the char residue of kraft/APP/AlPi was higher than that of kraft/APP, which indicated the kraft/APP/AlPi had better flame retardancy.
Journal articles
Predictive advisory solutions for chemistry management, control, and optimization, TAPPI Journal March 2025
ABSTRACT: Process runnability and end-product quality in paper and board making are often connected to chemistry. Typically, monitoring of the chemistry status is based on a few laboratory measurements and a limited number of online specific chemistry-related measurements. Therefore, mill personnel do not have real-time transparency of the chemistry related phenomena, which can cause production instability, including deposition, higher chemical consumption, quality issues in the end-product and runnability problems. Machine learning techniques have been used to establish soft sensor models and to detect abnormalities. Furthermore, these soft sensors prove to be most useful when combined with expert-driven interpretation. This study is aimed at utilizing a hybrid solution comprising chemistry and physics models and machine learning models for stabilizing chemistry-related processes in paper and board production. The principal idea is to combine chemistry/physics models and machine learning models in a fashion close to white box modeling. A cornerstone in the approach is to formulate explanations of the findings from the models; that is, to explain in plain text what the findings mean and how operational changes can mitigate the identified risks. The approach has been demonstrated for several different applications, including deposit control in the wet end, both raw water treatment and usage, and wastewater treatment. This approach provides mill personnel with knowledge of identified phenomena and recommendations on how to stabilize chemistry-related processes. Instead of using close to black box machine learning models, a hybrid solution including chemistry/physics models can enhance the performance of artificial intelligence (AI) deployed systems. A successful way of gaining the trust from mill personnel is by creating a plain text explanation of the findings from the hybrid models. The correlation between the likelihood of a phenomena and disturbance and the explanations are derived and validated by application and chemistry and physics experts.
Magazine articles
Leveraging mill-wide big data sets for process and qualityimprovement in paperboard production, TAPPI Journal December 2024
Authors: Jianzhong Fu and Peter W. Hart | TAPPI J. 15(5): 309(2016) - ABSTRACT: The MWV mill in Covington, VA, USA, experienced a long term trend of increasing episodes of paper indents that resulted in significant quantities of internal rejects and production downtime. When traditional troubleshooting techniques failed to resolve the problem, big data analysis techniques were employed to help deter-mine root causes of this negative and increasingly frequent situation. Nearly 6000 operating variables were selected for a deep dive, multi-year analysis after reviewing mill-wide process logs and 60000+ PI tags (data points) collected from one of the major data historian systems at the MWV Covington mill. Nine billion data points were collected from November 2011 to August 2014. Strategies and methods were developed to format, clean, classify, and sort the various data sets to compensate for process lag time and to align timestamps, as well as to rank potential causes or indicators. GE Intelligent Platforms software was employed to develop decision trees for root cause analysis. Insights and possible correlations that were previously invisible or ignored were obtained across the mill, from pulp-ing, bleaching, and chemical recovery to the papermaking process. Several findings led the mill to revise selected process targets and to reconsider a step change in the drying process. These changes have exhibited significant impacts on the mill’s product quality, cost, and market performance. Mill-wide communications of the identified results helped transform the findings into executable actions. Several projects were initiated.
Journal articles
Magazine articles
Review of coating cracking and barrier integrity on paperboard substrates, TAPPI JournalDecember 2024
Authors: Joel C. Panek and Peter W. Hart | TAPPI J. 21(11): 589(2022) - ABSTRACT: Barrier packaging formats are major growth areas for the pulp and paper industry. It is technically challenging to maintain barrier properties during converting and end-use applications. Improved manufacturing capabilities and coating formulation knowledge will help maintain barrier integrity and enable growth of barrier products in challenging applications. These improvements will accelerate product development and commercialization, and allow faster response to product performance issues such as cracking. The literature on coating cracking provides knowledge mostly on the effects of coating formulations and to a lesser extent on substrate effects. Despite a large number of publications dedicated to coating failures, the approach to improve coating cracking remains empirical, and the transferability between studies and to real life applications has not been well established. Model development that successfully predicts commercial performance is in its infancy. However, some of these simplified models do a fairly good job predicting experimental data. The current work reviews the state of understanding as regards coating and barrier cracking and highlights the need for more research on cracking and barrier integrity.
Journal articles
Magazine articles
Editorial: New coating grades require new tests: Barrier performance inside the package, TAPPI Journal November 2024
The TAPPI Journal special Coating issue is an annual issue that focuses on paper coating and coated papers. It is drawn from presentations at TAPPICon and from other submissions on the topic of paper coating. The TAPPICon 2024 Coating track was rich in high-quality technical content. In fact, the papers were of such significance that Coating members of the TAPPI Journal Editorial Board, which include me, Gregg Reed, and Gregory Welsch, decided that a second paper coating-related special issue would be appropriate for the TAPPI Journal editorial calendar. In addition to the current issue on Barrier Coating Testing, there will be another issue on Coating Fundamentals in early 2025.
Journal articles
Magazine articles
Quantification of block testing for coated paper substrates, TAPPI Journal November 2024
ABSTRACT: Block resistance is a critical property for coated paper and board substrate that will be rolled, stacked, or otherwise contact itself after coating. Small differences in the coated substrate’s blocking can determine whether the substrate can be successfully used for its designated purpose. However, this crucial property is typically evaluated using a qualitative scale that is based on subjective operator ratings and impacted by factors that include: (1) sound of coated substrate during separation, and (2) force with which substrates are separated. This paper tests the hypothesis that quantifying the block test by measuring the force required to peel samples apart improves the test by: (1) providing more standardized testing conditions by controlling peel force and rate; (2) more clearly differentiating samples that experience minimal to some blocking; and (3) maintaining customizability to evaluate customer-specific test conditions. The method developed in this study uses a standard block tester and block testing conditions, but it peels the coated paper samples using a hot tack/heat seal instrument with force measurement capabilities. This paper demonstrates, using the instrument’s heat seal capabilities, that it can measure peel forces that represent the full range of observable block scores. The efficacy of this method was evaluated by having a group of trained operators engage in a randomized, blind experiment where they assessed block resistance on a set of coated paper samples using a modified qualitative block scale and compared their results to force measurements collected using the proposed method. The sample set included two coatings that have successfully run in commercial trials with minimal blocking, and one coating that experienced significant blocking in commercial trials despite only exhibiting some blocking at standard block test conditions in laboratory testing. The quantitative test method presented in this paper clearly differentiated these samples, whereas the qualitative assessment could not predict which samples had suitable block resistance for commercial use. As any tensile tester capable of measuring with 0.1 N resolution can be used for the Quantitative Block Test, the proposed method can be widely adopted. Furthermore, this method can be used for any block condition.
Journal articles
Magazine articles
Test method and coating composition impact on measured moisture vapor transmission rate for waterborne coatings on paper, TAPPI Journal November 2024
ABSTRACT: Moisture vapor barrier is one of the necessary performance attributes for paper packages. Two methods are typically employed to assess the moisture vapor transmission rate (MVTR): the gravimetric cup method (ASTM E96) and the MOCON method (ASTM F1249). While those tests have been compared for free standing polymeric films, less is understood about their application in coated paper. Our results show that, despite a general agreement between the two methods, discrepancies exist where test protocols and material properties of coated paper impact the MVTR measurement. The measurement discrepancies can be explained by differences in local moisture concentration. Our study provides new insights on moisture vapor barrier assessment of waterborne coatings on paper and implications for achieving paper packages with improved barrier performance.
Journal articles
Magazine articles
Evaluation of folding effects on coating damage, TAPPI Journal November 2024
ABSTRACT: Barrier coatings on paperboard need to maintain integrity during converting and end-use for effective barrier performance. Folding is one of the most common deformations during converting; however, factors that affect damage during folding are not well defined. This is partly because methods to fold specimens and characterize damage are not standardized and the results are generally not transferable. In this work, we describe a method to fold paper specimens precisely and reproducibly. The keys to folding include using a defined geometry and controlled deformation. Multiple methods can be used to quantify damage; in this case, we use differences in permeability as a measure of how the coating becomes more open. Damage is sensitive to the degree of compression after the initial folding. Using a shim for support provides a defined amount of compression and minimizes the sensitivity to the applied pressure.
Journal articles
Magazine articles
Colloid chemical aspects of paper formation in the presence of nanofibrillated cellulose and cationic starch, TAPPI Journal September 2024
ABSTRACT: A series of experimental tests were carried out to examine colloidal-scale consequences of optionally treating nanofibrillated cellulose (NFC) with cationic starches of different charge density and dosage (0.5% or 2.0% by weight), adding that material to a furnish prepared from 100% recycled copy paper, and then subjecting the mixture to very different levels of hydrodynamic shear. Tests included optical microscopy, sediment volume tests, sediment velocity tests, and “percent fines” assessment by means of a fiber quality analyzer (FQA). In addition, the zeta potential and charge demand of the studied materials were evaluated. Optical imaging revealed that cationic starch treatment of the NFC tended to agglomerate it into multiparticle clusters, which sometimes could be mostly redispersed by hydrodynamic shear. Subsequent addition of the starch-treated NFC to the default furnish resulted in much of the colloidal material becoming attached to fibers. Subsequent shearing of the mixtures was at least partly effective in separating the clusters of NFC from the fiber surface, resulting in essentially a two-component mixture. Multiparticle NFC clusters coexisted with the fiber suspension, sometimes attached and sometimes not, depending on the details of treatments. Sediment volume tests showed that systems containing cationic starch-treated NFC tended to have a higher density after settling in comparison to untreated NFC; these findings are consistent with the cationic starch acting as a stabilizer on the solid surfaces, allowing them to slide past each other during the settling process. Application of intense hydrodynamic shear tended to result in denser sediment. Results of tests with the sediment velocity messurement and the FQA percent fines assessment did not correlate well with changes in test conditions considered in this study.