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Journal articles
Relationship of Surface Strength and Bulk Strength Properties in Uncoated Woodfree Paper, TAPPI JOURNAL February 2011
Relationship of Surface Strength and Bulk Strength Properties in Uncoated Woodfree Paper, TAPPI JOURNAL February 2011
Journal articles
In-Situ Measurements of Sootblower Jet Impact in a Recovery Boiler, TAPPI JOURNAL February 2011
In-Situ Measurements of Sootblower Jet Impact in a Recovery Boiler, TAPPI JOURNAL February 2011
Journal articles
Effects of Loblolly Pine Wood and Pulp Properties on Sheet Characteristics, TAPPI JOURNAL February 2011
Effects of Loblolly Pine Wood and Pulp Properties on Sheet Characteristics, TAPPI JOURNAL February 2011
Journal articles
Magazine articles
Editor's Note: Great expectations, TAPPI JOURNAL January 201
Editor's Note: Great expectations, TAPPI JOURNAL January 2011
Journal articles
Magazine articles
The use of hollow sphere pigments as strength additives in paper and paperboard coatings—Part 1: The predictive nature of packing models on coating properties, TAPPI Journal November 2020
ABSTRACT: Hollow sphere pigments (HSPs) are widely used at low levels in coated paper to increase coating bulk and to provide gloss to the final sheet. However, HSPs also provide an ideal system through which one can examine the effect of pigment size and particle packing within a coating due to their unimodal and tunable particle sizes. The work presented in Part 1 and Part 2 of this study will discuss the use of blends of traditional inorganic pigments and HSPs in coating formulations across a variety of applications for improved coating strength. Part 1 of this study focuses on the theory of bimodal spherical packing and demonstrates the predictive nature of packing models on the properties of coating systems containing HSPs of two different sizes. This study also examines conditions where the model fails by examining the effect of particle size on coating strength in sytems like thermal paper basecoats where the non-HSP component has a broad particle size distribution, and how these surprising trends can be used to generate better-than-expected thermal printing performance in systems with low HSP/clay ratios. Part 2 of this study focuses on the incorporation of HSPs of different particle sizes into paperboard formulations to affect coating strength and opacity.
Journal articles
Magazine articles
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.
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
Magazine articles
Crossflow filtration of green liquor for increased pulp production, improved green liquor quality, and energy savings, TAPPI JOURNAL October 2020
ABSTRACT: A new green liquor filtration system has been installed and commissioned at the Ence pulp mill in Pontevedra, Spain. The filtration system is based on microfiltration and was developed in collaboration with the KTH Royal Institute of Technology in Stockholm, Sweden. The patented method for efficient purification of green liquor decreases the non-process element (NPE) content by providing more efficient solids/liquid separation, reducing energy and chemical consumption in pulp mills and increasing production capacity by eliminating certain capacity bottlenecks. The process has been continuously tested at the Aspa Bruk Mill outside Askersund, Sweden, since 2013. The technology has proven to create nearly particulate-free green liquor during the purification process. The technology can also be used to polish white liquor to provide higher pulp quality.To provide for a simple and cost-effective installation, the system was designed as a skid-mounted unit that is pre-piped, instrumented, and tested before shipment. The system is modular and allows for easy expansion of capacity. This paper discusses the process design, process integration, and startup of the new system, along with experiences from the first months of operation.
Journal articles
Magazine articles
Multilayering of conventional latex-based dispersion coatings containing small amounts of silica nanospheres: Runnability on a pilot scale flexographic coater and barrier performance, TAPPI Journal November 2023
ABSTRACT: The addition of functional coatings to packaging materials is a key requirement for increasing their performance and creating innovative packaging solutions. Flexography, a cost-effective printing method commonly used to print information and graphics directly onto a wide variety of packaging substrates, shows good potential for applying functional coatings. In this study, conventional clay-latex coating formulations containing approximately 1.3 wt% silica nanospheres were applied to a linerboard using a pilot scale flexographic printing web press. The performance of multilayered silica nanosphere-based coatings was compared with conventional coatings containing talc and/or wax dispersion in terms of coating grammage, runnability, and barrier performance. Coating grammage increased with an increased number of coating layers and a significant decrease in both the water vapor transmission rate (WVTR) and the direct water uptake of water (Cobb 120 wettability test) was observed for coatings containing silica nanoparticles. In general, the silica nanosphere-based coatings performed better than talc-based coatings. Talc/wax-based coatings had the highest variation in surface roughness due to an uneven distribution and variations of coating layers.
Polyvinylamine as a wet-end additive: Effects of pH and anionic contamination, TAPPI Journal May 2024
ABSTRACT: The effects of polyvinylamine (PVAm) on papermaking process attributes and handsheet quality were evaluated for a recycled copy paper furnish in a near neutral-to-alkaline pH range. The degree of protonation of primary amine groups, such as those in PVAm, is known to decrease with increasing pH. Streaming potential tests surprisingly showed that a high treatment level of PVAm on the copy paper furnish was able to maintain a net positive zeta potential up to pH of about 11, whereas charge demand titrations indicated that PVAm maintained its positive charge character up to about pH 10. Favorable dewatering was observed when the furnish had been pretreated with 1% polyacrylate dispersant prior to treatment with PVAm at the 0.5% level, and the mass of filtrate increased slightly with increasing pH. First-pass retention tests showed poor retention efficiency in systems where the furnish had been treated with the dispersant, then PVAm, in an unfavorable pH range of about 9 to 9.5. Higher retention was achieved both at pH 8.2 and at pH 10 or higher. Handsheets showed superior breaking length results in the systems where the stock had been pretreated with the dispersant, though strength decreased strongly with increasing pH. Differences in filler content, as indicated by ash analysis, were not large enough to account for the observed strength differences. Formation uniformity was substantially increased by the pretreatment with dispersant, even in the presence of PVAm and throughout the studied pH range.