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The use of hollow sphere pigments as strength additives in paper and paperboard coatings—Part 2: Optimization in paperboard formulations for opacity and strength, TAPPI Journal November 2020
ABSTRACT: This report aims to summarize the efforts in testing the properties of coatings for paperboard utilizing hollow sphere pigments (HSPs). HSPs are known to effectively scatter light and replace titanium dioxide (TiO2) in architectural coating formulations. The effect of the particle size and void fraction was evaluated, along with many coating parameters, including level of addition, binder chemistry, and blends of two HSPs. The small HSPs that have optimized voids for scattering light showed equivalent strength to the TiO2-containing control. The strength data was surprising, particularly the improvement in strength for coatings containing large particle size HSPs. Because of this increase in strength, four parts of binder could be removed, which allowed for higher brightness while not compromising other properties, including hot melt glueability. These trends held true using different binder chemistries (styrene acrylic, vinyl acrylic, and styrene butadiene). Upon refining the formulations further, blends of two HSPs showed further benefit.
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Communicate, Collaborate: Steve Voorhees on Impactful Leadership, Paper360º November/December 2020
Communicate, Collaborate: Steve Voorhees on Impactful Leadership, Paper360º November/December 2020
Journal articles
Magazine articles
Can’t Be On-Site? Try Virtual PM Audits, Paper360º November/December 2020
Can’t Be On-Site? Try Virtual PM Audits, Paper360º November/December 2020
Journal articles
Magazine articles
RMM Beliefs: Part I, Paper360º November/December 2020
RMM Beliefs: Part I, Paper360º November/December 2020
Journal articles
Magazine articles
Improving paper wet strength via increased lignin content and hot-pressing temperature, TAPPI JOURNAL October 2020
ABSTRACT: It is known that the strength properties of wood-based paper materials can be enhanced via hot-pressing techniques. Today, there is a desire not only for a change from fossil-based packaging materials to new sustainable bio-based materials, but also for more effective and eco-friendly solutions for improving the dry and wet strength of paper and board. Against this background, hot pressing of paper made from high yield pulp (HYP), rich in lignin, becomes highly interesting. This study investigated the influence of pressing temperature and native lignin content on the properties of paper produced by means of hot pressing. Kraft pulps of varied lignin content (kappa numbers: 25, 50, 80) were produced at pilot scale from the same batch by varying the cooking time. We then studied the effect of lignin content by evaluating the physical properties of Rapid Köthen sheets after hot pressing in the temperature range of 20°C•200°C with a constant nip pressure of 7 MPa. The pilot-scale cooked pulps were compared with reference samples of mill-produced northern bleached soft-wood kraft (NBSK) pulp and mill-produced chemithermomechanical pulp (CTMP).Generally, the results demonstrated that lignin content had a significant effect on both dry and wet tensile index. All of the pilot cooked pulps with increased lignin content had a higher tensile index than the reference NBSK pulp. To obtain high tensile index, both dry and wet, the pressing temperature should be set high, preferably at least 200°C; that is, well above the glass transition temperature (Tg) for lignin. Moreover, the lignin content should prefera-bly also be high. All kraft pulps investigated in this study showed a linear relationship between wet strength and lignin content.
Journal articles
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Coarse Filtration is the ´First Line of Defense’, Paper360º January/February 2021
Coarse Filtration is the ´First Line of Defense’, Paper360º January/February 2021
Journal articles
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TAPPI Journal Summaries, Paper360º January/February 2021
TAPPI Journal Summaries, Paper360º January/February 2021
Journal articles
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RMM Part 2: Belief-Driven Strategy, Paper360º January/February 2021
RMM Part 2: Belief-Driven Strategy, Paper360º January/February 2021
Journal articles
Magazine articles
Three-dimensional visualization and characterization of paper machine felts and their relationship to their properties and dewatering performance, TAPPI Journal July 2021
ABSTRACT: Polymeric felts are commonly used in the papermaking process on the paper machine wet end, in the press section, and in the dryer section. They provide an important function during paper manufacturing, including as a carrier or support; as a filter media assisting with water removal on the paper machine; in retention of fibers, fines, and fillers; and in some applications, such as tissue and towel, to impart key structural features to the web. These felts can have highly interwoven complex internal structures comprised of machine direction and cross-machine direction yarns of varying sizes and chemical compositions. Here, we present a non-intrusive three-dimensional (3D) image visualization method using advanced X-ray computed tomography (XRCT). This method was used to characterize the complex 3D felt structure and determine the water removal characteristics of some commonly used paper machine felts. The structural features analyzed include porosity; specific pore-yarn interfacial surface area; 3D pore size distribution; 3D fiber or yarn-size distribution; and their variations through the thickness direction. The top, middle, and bottom layers of the felt have very different structures to assist with water removal and impart paper properties. The size distribution of the yarns, as well as the pores in the different layers of the felt, are also inherently different. These structural features were non-intrusively quantified. In addition, variation in the structural characteristics through the thickness of the felts and its potential role in papermaking is explored. In addition to the 3D structural characteristics, permeability characteristics and water removal characteristics, including rewetting of select felt samples, have also been experimentally determined. It is interesting to observe the relationship between key structural features and permeability and water removal characteristics. These relationships can provide additional insights into press felt design, as well as ways to improve product properties and the dewatering efficiency and productivity of the paper machine.
Journal articles
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Uruguay Prepares to Open a Gateway to the World, Paper360º July/August 2021
Uruguay Prepares to Open a Gateway to the World, Paper360º July/August 2021