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Multifunctional barrier coating systems created by multilayer curtain coating, TAPPI Journal November 2023
ABSTRACT: Functional coatings are applied to paper and paperboard substrates to provide resistance, or a barrier, against media such as oil and grease, water, water vapor, and oxygen, for applications such as food packaging, food service, and other non-food packaging. Today, there is increasing interest in developing recyclable and more sustainable approaches for producing these types of packages. This paper focuses on water-based barrier coatings (WBBC) for oil and grease resistance (OGR), water, moisture vapor transmission rate (MVTR), and oxygen barrier performance. The main goal is to create coated systems that can achieve more than one barrier property using multilayer curtain coating (MLCC) in a single application step. One advantage is in optimizing coating material cost with the use of functional chemistry in confined layers where performance is balanced within the coating layered structure. This allows simultaneous application of layers of different polymer types in one step to achieve the appropriate performance needs for a given barrier application. This paper provides working examples of using MLCC to create coating structures with multiple barrier properties in a single application pass. Barrier polymers studied include styrene butadiene, styrene acrylate, starch-containing emulsions, and polyvinyl alcohol. The paper also shows the effect of increasing the pigment volume concentration with platy clay or fine ground calcium carbonate on MVTR and OGR barrier properties.
Journal articles
Magazine articles
Surface energy considerations for offset printing of coated paper and paperboard, TAPPI Journal November 2023
ABSTRACT: Offset printing of coated paper involves the complex interactions of ink with a surface that is characterized by three major properties: roughness, porosity, and related pore network structure and surface chemistry (related to surface free energy [SFE]). The effects of porosity and roughness are relatively well understood and are documented in the literature, whereas the influence of surface chemistry is much less studied and therefore the focus of this paper. The key results shown include: i) Coating porosity has a negligible effect on SFE determination by contact angle using two fluids. ii) The chemistry of the latex polymer in the coating formulation dominates the influence on SFE compared to pigment, with any surface energy differences present in the pigment being almost completely masked by latex. iii) Wetting agent and corona treatment can impact water absorption rate and surface spreading of water, resulting in small differences in printability. Increasing the concentration of the surfactant on a coated surface indicates switching orientation of the surfactant molecules, giving a “step wise” printing result. When looking to improve offset printability by selection of different pigments, the variation in SFE is less important than variation in either surface roughness or porosity.
Journal articles
Magazine articles
Rewet in wet pressing of paper, TAPPI JOURNAL September 2018
Rewet in wet pressing of paper, TAPPI JOURNAL September 2018
Journal articles
Magazine articles
Upscaling of foam forming technology for pilot scale, TAPPI JOURNAL August 2019
ABSTRACT: The need for production cost savings and changes in the global paper and board industry during recent years have been constants. Changes in the global paper and board industry during past years have increased the need for more cost-efficient processes and production technologies. It is known that in paper and board production, foam typically leads to problems in the process rather than improvements in production efficiency. Foam forming technology, where foam is used as a carrier phase and a flowing medium, exploits the properties of dispersive foam. In this study, the possibility of applying foam forming technology to paper applications was investigated using a pilot scale paper forming environment modified for foam forming from conventional water forming. According to the results, the shape of jet-to-wire ratios was the same in both forming methods, but in the case of foam forming, the achieved scale of jet-to-wire ratio and MD/CD-ratio were wider and not behaving sensitively to shear changes in the forming section as a water forming process would. This kind of behavior would be beneficial when upscaling foam technology to the production scale. The dryness results after the forming section indicated the improvement in dewatering, especially when foam density was at the lowest level (i.e., air content was at the highest level). In addition, the dryness results after the pressing section indicated a faster increase in the dryness level as a function of foam density, with all density levels compared to the corresponding water formed sheets. According to the study, the bonding level of water- and foam-laid structures were at the same level when the highest wet pressing value was applied. The results of the study show that the strength loss often associated with foam forming can be compensat-ed for successfully through wet pressing.
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.
Journal articles
Maximization of profit through optimal selection of inventory levels and production rates in pulp and paper mills, TAPPI JOURNAL, July 2003, Vol. 2(7) (166KB)
Maximization of profit through optimal selection of inventory levels and production rates in pulp and paper mills, Solutions! & TAPPI JOURNAL, July 2003, Vol. 2(7) (166KB)
Journal articles
Influence of fines on sheet delamination in condebelt drying and recyclability of condebelt-dried linerboard, TAPPI JOURNAL, June 2003, Vol. 2(6) (158KB)
Influence of fines on sheet delamination in condebelt drying and recyclability of condebelt-dried linerboard, Solutions! & TAPPI JOURNAL, June 2003, Vol. 2(6) (158KB)
Journal articles
Evaluation of a laser-optical resin particle counter, Solutions! & TAPPI JOURNAL, March 2003, Vol. 2(3) (239KB)
Evaluation of a laser-optical resin particle counter, Solutions! & TAPPI JOURNAL, March 2003, Vol. 2(3) (239KB)
Journal articles
Application of yellowing inhibitors to improve the brightness stability of coated mechanical papers, TAPPI JOURNAL, May 2003, Vol. 2(5) (195KB)
Application of yellowing inhibitors to improve the brightness stability of coated mechanical papers , Solutions! & TAPPI JOURNAL, May 2003, Vol. 2(5) (195KB)