Response to isopropanol or ionic/non-ionic surfactant in the competitive imbibition of water and alkane into calcium carbonate structures, 2010 TAPPI Advanced Coating Fundamentals Symposium

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This work explores the relationship between polar and non-polar liquids and their interaction with typical porous coating structures, consisting of 100 % dispersed calcium carbonate. The effects of surface active agents, i.e. isopropanol and ionic/non-ionic surfactant are investigated. These surface active agents are currently being employed and developed for the printing industry. Absorption rates into compressed tablets of ground calcium carbonate, with and without the presence of latex, are observed. Polyacrylate dispersant, used in manufacture, renders the pigment surface both hydrophilic and hygroscopic, and therefore controls the differential dynamic wetting characteristics of the porous structure for either polar or non-polar liquids. In competition with non-polar hexadecane saturating the pore structure of a latex-free sample, polar water displaces the non-polar liquid instantaneously, causing disintegration of the packed porous structure. In the presence of latex binder, however, the structurally destructive pressure is contained, and the uptake of polar water is retarded. The required pre-wetting action of water vapour diffusion on the polyacrylate pigment surface is considered to be an integral part of the successful competition between oil and water in the offset printing process, as non-polar oil absorbs steadily into a water pre-saturated structure. Additionally, isopropanol likely promotes miscibility and emulsification more so than ionic/non-ionic surfactant. This behavior is possibly relates to the comparative molecular weights of the active agents which differentiate their surface energy modifying mechanism from those of the ionic pigment dispersant and binder stabilizers/carboxylation. The use of surface active agents enables potentially a more homogeneous response to the competitive imbibition environment within the coating structure.