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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
Investigation of the effect of press and paper variables on linting during the offset printing of newsprint, TAPPI JOURNAL September 2007
Investigation of the effect of press and paper variables on linting during the offset printing of newsprint, TAPPI JOURNAL September 2007
Journal articles
Relationship Between Gloss and Surface Texture of Coated Papers, TAPPI JOURNAL April 2008
Relationship Between Gloss and Surface Texture of Coated Papers, TAPPI JOURNAL April 2008
Journal articles
Application of lipase to reduce ONP flotation rejects: Part 2. Reduction of flotation rejects, TAPPI JOURNAL, August 2008
Application of lipase to reduce ONP flotation rejects: Part 2. Reduction of flotation rejects, TAPPI JOURNAL, August 2008
Journal articles
Water release from fractionated stock suspension. Part 2. Effects of consistency, flocculants, shear, and order of mixing, TAPPI JOURNAL, August 2008
Water release from fractionated stock suspension. Part 2. Effects of consistency, flocculants, shear, and order of mixing, TAPPI JOURNAL, August 2008
Journal articles
Flow dynamics of pulp fiber suspensions, TAPPI JOURNAL, August 2008
Flow dynamics of pulp fiber suspensions, TAPPI JOURNAL, August 2008
Journal articles
Using peel as a measure of paper surface strength, Solutions! & TAPPI JOURNAL, July 2004, Vol. 3(7) (473KB)
Using peel as a measure of paper surface strength, Solutions! & TAPPI JOURNAL, July 2004, Vol. 3(7) (473KB)
Journal articles
Rosin sizing under neutral-alkaline papermaking conditions, TAPPI JOURNAL, Online Exclusive, July 2004, Vol. 3(7) (212KB)
Rosin sizing under neutral-alkaline papermaking conditions, TAPPI JOURNAL, Online Exclusive, July 2004, Vol. 3(7) (212KB)