PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL Volume 7, Number 3, 2021
COATING “ Synergetic effect of cationic starch (ether/ester) and Pluronics for improving inkjet printing quality of office papers ”, Mohit Sharma, Roberto Aguado, Dina Murtinho, Artur J. M. Valente & Paulo J. T. Ferreira, Cellulose , Vol.28, pp.10609 – 10624 (2021). Improving the printability of paper is still a relevant challenge, despite the fast development of digital communications. While it is well-known that cationic starches enhance ink density, their commercial paper-grade forms are limited to ethers with low degree of substitution. This work addresses the underexplored potential of highly substituted cationic starch for paper coating and its combination with tri-block polymers, namely Pluronics (P123 and F127), taking advantage of their supramolecular interactions with amylose chains. For that purpose, cationic starch ether and ester (starch betainate), both with a degree of substitution of 0.3, were synthesized by alkaline etherification and by transesterification, respectively. Paper without any surface treatment was subjected to one-side bar coating with suspensions encompassing those products and Pluronics, besides other common components. Black, cyan, yellow and magenta inks were printed on all coated papers through an inkjet printer. Key properties of printing quality such as the gamut area, gamut volume, optical density, print-through, inter-color bleed and circularity were measured in a controlled temperature-humidity environment. For instance, a formulation with cationic starch (ether/ester) and P123 improved the gamut area by 16 – 18% in comparison to native starch-coated paper sheets. Interestingly, the individual assessment of each component showed that cationic starch ether, starch betainate and P123 only improved the gamut area by 5.6%, 8.9% and 6.8%, respectively. Finally, but not less importantly, starch betainate was found to quench optical brightening agents to a lesser extent than cationic starch ethers. “ Fabrication of high mechanical properties papers coated with CMC-based nanocomposites containing nanominerals synthesized from paper waste ”, Faegheh Alsadat Mortazavi Moghadam, Hossein Resalati, Sousan Rasouli & Ghasem Asadpour, Cellulose , Vol.28, pp.11153 – 11164 (2021). In this work, nanokaolin (K) and nanometakaolin (MK) were synthesized from waste paper via planetary ball milling and characterized by means of X-ray diffraction (XRD), Fourier transform infrared vibrational spectroscopy (FTIR), and scanning electron microscopy (SEM). Suspensions of carboxymethyl cellulose (CMC) and the synthesized nanominerals at 1.5, 3, 6, and 9% led to nanocomposites 30, 60, 90, and 120 μm thick. Nanocomposites coated papers were analyzed by means of XRD, FTIR, SEM, tensile index, strain rate, burst index, and air passage resistance. The highest tensile index, burst index, and air permeability resistance values of 80.78 N.mg, 5.24 kPa.m 2 g, and 286.66 ml/min, respectively, were obtained for CMC-9%MK-120. These results indicated that paper coated with CMC nanometakaolin composite is suitable for packaging. “ Effects of Chitin Nanocrystals on Coverage of Coating Layers and Water Retention of Coating Color ”, Ruoshi Gao, Yi Jing, Yeyan Ni & Qiwen Jiang, Journal of Bioresources and Bioproducts , published online. This study assessed the applicability of chitin nanocrystals prepared by 2, 2, 6, 6-Tetramethyl-1-Piperidine-1-oxyl radical (TEMPO)-mediated oxidation in traditional papermaking coating color systems. The α - chitin nanocrystals (CTNCs) with different carboxyl content, size, and morphology were prepared from crab shells by alkali pretreatment and TEMPO-mediated oxidation in the water at pH 10, and then the ratio of CTNCs to latex was applied to traditional coating color system to replace part of latex. The results showed that when the amount of NaClO added as co-oxidant in the oxidation was 15.0 mmol/g of chitin, the carboxyl content of alkali-pretreated CTNCs was up to 0.76 mmol/g. The amount of carboxyl groups presented
Technical Abstracts
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