Coated Paper Stiffness: A Practical Perspective, 2000 International Printing & Graphic Arts Conference Proceedings

Linda H. Kim-Habermehl, Mark Pollock, Charles Kan, John Oates, Garth Williamson--As coated paper producers strive for improved profitability in an increasingly competitive global marketplace, efforts to cost-effectively produce differentiated products are becoming ever more focused. Recent trends such as basis weight reduction, aggressive efforts to reduce raw material costs, and the increasing use of calcium carbonate in coating formulations have reduced the stiffness of coated paper and paperboard. Higher stiffness is typically desired to make a coated paper feel like it is of a heavier basis weight or quality than it actually is. Higher stiffness improves machine runnability during coating and printing – the paper’s ability to feed into a sheet fed printing press as well as ease of handling. One approach to increased stiffness is the use of stiff binders. However, a key issue with stiff binder performance is balancing high stiffness with printability, because of dryer sensitivity associated with stiff binders. Achieving this balance typically requires a systems approach with consideration of processing parameters such as finishing conditions. This paper provides an overview of coated paper stiffness from a practical perspective encompassing discussion of the following: correlations of stiffness to modulus, significant factors affecting coated paper stiffness, and critical issues associated with stiffness performance.