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Investigation of the Cellulose-Water Relationship by the Pressure Plate Method, TAPPI Journal July 2022
ABSTRACT: The swelling and water retention properties of pulp fibers are of basic importance in papermaking.
Journal articles
Magazine articles
Web instability in the open draw and the impact on paper machine efficiency, TAPPI Journal May 2022
ABSTRACT: Paper is most likely to break in the first open draw on a paper machine where it is unsupported, wettest, and weakest. Tension is applied to peel the web from the roll surface, as well as minimize web flutter in the open draw. The average tension is well below the breaking point and is often set by adjusting the speed difference between the press and the next machine element by visually observing the behavior of the web. However, machine direction variations caused by instabilities in the paper machine can cause tension swings that exceed the strength of the web. Measurement of the web’s release point from press rolls on pilot and commercial paper machines was used to identify the cause of tension instabilities. Variations in the speed of the paper machine drives and the work of adhesion from the press roll surface were identified as key factors. Fluctuations of paper moisture, which affects the elastic modulus and strength of the web, appear to be less important.
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Editorial: The road to sustainable packaging: New research on aqueous barrier coating, TAPPI Journal November 2022
Authors: Joel C. Panek and Peter W. Hart | ABSTRACT: This TAPPI Journal Special Coating Issue looks at hot topic research being done in coatings for paper and paperboard. We can feel the “earth shifting” in paper and paper-board packaging due to the strong call by consumers and brand owners for more sustainable and environmentally friendly options. This is the first TAPPI Journal Special Coating Issue to highlight efforts within the paper coating community to produce more sustainable packaging.
Journal articles
Magazine articles
Improvements in oil and grease resistance (OGR) test methodology for waterborne barrier coatings, TAPPI Journal November 2022
ABSTRACT: Paper-based food packaging is becoming more popular due to consumer demands for sustainable packaging options. Waterborne paper coatings that provide performance properties (i.e., resistance to oil and grease) not inherent to paper and board substrates offer improved sustainability profiles over earlier paper treatment options, including fluorocarbon treatment and coating with extruded plastics. The continued development of new paper coating technologies requires re-evaluation of current test methods and development of new methods to ensure lab evaluations can serve as accurate predictors of real-world performance. This paper provides an overview of commonly used oil and grease resistance (OGR) test methods within the paper coatings industry, and then describes improvements and developments made to two key methods: the 3M Kit test and an internally developed oil breakthrough test. The combined use of these adapted methods provides a more efficient testing workflow and a more complete understanding of the OGR performance of barrier coatings.
Journal articles
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Z-directional testing of paperboard in combined tensile and compression loading, TAPPI Journal May 2024
ABSTRACT: The out-of-plane properties of paperboard are important in several converting applications such as printing, sealing, creasing, and calendering. A juxtaposed tensile and compression curve in the z direction (ZD) will, however, appear to have a kink or discontinuity at 0 stress. The purpose of the present work is to capture the continuous transition between tension and compression and to increase the understanding of the complex ZD properties of paperboard by cyclic testing. In this attempt to unify the ZD tensile and compressive behavior of paperboard, samples were laminated to the testing platens using heat seal laminate film. The method for adhering the samples was compared to samples that were laminated and glued to the testing platens. The edge effects of the cutting method were evaluated in compression testing with samples not attached to the testing platens. The flat slope seen in the initial part of the pure compression curve disappeared when the samples were laminated to the testing platens. The flat slope was instead replaced by a continuous response in the transition across 0 N. The stiffness in the transition region resembled the response in tensile testing. When the testing is cycled, the material exhibits a history dependence. Starting the cycle in either compression or tensile will show an effect on the stiffness at the transition, as well as the compressive stiffness. However, the ultimate tensile strength is unaffected.
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
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Experimental investigations into fold cracking of double coated barrier dispersion coatings, TAPPI Journal November 2024
ABSTRACT: The trend for replacing single-use plastics with fiber-based barrier coated board packaging has prompted a significant amount of research. There are many proposed ways of providing suitable packaging for applications like food service. Among these are dispersion coated barriers on board, as well as laminated boards that can be produced using conventional polyethylene (PE) or new biodegradable plastics. Minerals have also been shown to be suitable additives to these coatings for improving barrier performance through surface chemistry and by increasing the tortuosity of the pathway through the barrier layer. They also improve the cost effectiveness of the layer by lowering the material cost and raising the solids content, and by improving hold out of the functional layers, leading to a reduction in the amount of barrier coating needed to meet a given performance requirement. Minerals can also aid in the barrier handling in terms of rheology and reduced “stickiness,” as well as blocking of the films. When incorporated as fillers into extruded films, improved adhesion of the film to the board has been reported. One of the remaining challenges is the potential for cracking at the fold during converting and the loss of barrier performance that this can lead to. In this work, we systematically looked at the impact of mineral type and level in a dispersion coating. We assessed the differences in performance resulting from different coating application methods for the precoat layer by looking at the cracking tendency and loss of barrier functionality after folding for both the precoat alone and the final double coated sheets. Barrier results include moisture vapor transmission rate (MVTR), viscous vegetable oil, and the fluid blue stain in industrial methylated spirits (IMS) and Cobb water absorption, both before and after folding.
Journal articles
Magazine articles
Editorial: Concentrated content: TAPPI Journal special issues create research visibility, TAPPI Journal September 2024
You may have noticed that TAPPI Journal often brings readers special focused issues from time to time. Over the years, these issues have covered a range of topics, including wet-end technology, recovery cycle, foam forming, coating, additives, biorefinery, nanotechnology, lignin, pulping, recycling, university research, and more.
Journal articles
Magazine articles
Citrus-based hydrocolloids: A water retention aid and rheology modifier for paper coatings, TAPPI Journal July 2019
ABSTRACT: The rheological and dewatering behavior of an aqueous pigmented coating system not only affects the machine runnability but also affects the product quality. The current study describes the use of natural hydrocol-loids derived from citrus peel fibers as a rheology modifier in paper coating applications. The results were compared with carboxymethyl cellulose (CMC) in a typical paper coating system. Water retention of the coating formulation was increased by 56% with citrus peel fibers compared to a default coating, and it also was higher than a CMC-containing coating. The Brookfield viscosity of paper coatings was found to increase with citrus peel fibers. Compared to CMC, different citrus peel fibers containing coating recipes were able to achieve similar or higher water retention values, with no change or a slight increase in viscosity. Coatings were applied on linerboard using the Mayer rod-coating method, and all basic properties of paper were measured to assess the impact of citrus peel fiber on the functional value of the coatings. Paper properties were improved with coated paper containing citrus peel fibers, including brightness, porosity, smoothness, surface bonding strength, and ink absorption.
Journal articles
Magazine articles
The evolution of reel statistical methods, TAPPI Journal June 2019
ABSTRACT: Multiple statistical methods for calculating the variance partition analysis (VPA) of reel data have existed for decades. In the paper industry, VPA is also commonly known as reel statistics. VPA commonly consists of total variance (TOT) that is then divided into three components: cross direction (CD), machine direction (MD), and residual (RES). A common mathematical procedure is referred to as ANOVA (analysis of variance). TAPPI Standard Test Method T 545 “Cross-machine grammage profile measurement (gravimetric method)” addresses paper testing and includes the ANOVA equations that have also been used to analyze scanning data.In the 1990s, TAPPI published TIP 1101-01 “Calculation and partitioning of variance using paper machine scanning sensor measurements,” which contained simple formulas that were easy to implement and could be used by a nov-ice to generate statistics on a spreadsheet. All involved quality control system (QCS) suppliers agreed to support this common method in their QCS. TIP 1101 was recently revised, and this paper concerns the analysis of data collected from a scanning sensor in a QCS and the creation of a common method for the calculation of reel statistics by TAPPI’s Process Control Division.