Competitive Absorption of Polar and Non-Polar Liquids into Latex Bound Porous Structures of Fine Ground Calcium Carbonate

Abstract

Fine calcium carbonate is frequently used as coating pigment, e.g. in paints, paper and board. Emulsion polymer latex provides a typical binder incorporated in such coatings. Exposure of the resulting porous structure to liquid, depending on latex concentration level, results in ab-and adsorption as the liquid is drawn into the structure by capillarity and the nature of the relative surface chemistry of the pores. Previous work has shown that typical coating structures act to separate oil components according to their surface energy characteristics and solubility index in respect to pigment surface and intra-latex diffusion. This study considers water and alkane (hexadecane) as model liquids. Absorption rate into compressed tablets of ground calcium carbonate is observed with and without the presence of latex. 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 liquid. In competition with hexadecane saturating the pore structure of a latex-free sample, polar water is seen to displace the non-polar liquid instantaneously, causing disintegration of the packed porous structure. In the presence of latex binder, however, the structurally destructive pressure this creates is contained, and retardation of the polar water is observed. 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.

Stimuli-Responsive Nanolatexes: Porating Films

“…Semipermeable coatings, however, can provide barriers to certain components and fields while allowing certain chemical components to easily pass, and porosity in coatings can provide desired optical effects, changes in interfacial adhesion, and a variety of flow and filtration effects. Porosity in latex coatings involves exceeding the critical pigment concentration, using porous pigments, or otherwise has included incorporation of some sort of poragen. , …”

“…Semipermeable coatings, however, can provide barriers to certain components and fields while allowing certain chemical components to easily pass, and porosity in coatings can provide desired optical effects, changes in interfacial adhesion, and a variety of flow and filtration effects. Porosity in latex coatings involves exceeding the critical pigment concentration, 8 using porous pigments, 9 or otherwise has included incorporation of some sort of poragen. 5,10 In this study we follow the report of Yan and Texter of nanolatexes derived from the ionic liquid surfactant acrylate, ILBr with MMA (methylmethacrylate) comonomer, and that exhibited colloidal stability in high salt.…”

Quantitative measurements of capillary absorption in thin porous media by the Automatic Scanning Absorptometer

“…Over the years, extensions to Darcy's law are made for deforming porous media (Anderson, 2005), unsteady flows (Khalifa et al, 2002), gravitational flows and multiphase liquid penetration (Muccino et al, 2010). Furthermore, the application of Darcy's law in different liquid -media combinations has been addressed (O'Loughlin et al, 2013;Cao et al, 2015;Ridgway and Schoelkopf, 2011;Gruener and Huber, 2011). In order to test and validate Darcy's law and to verify which extensions need to be taken into account for a specific liquid -media system, there is a need for experimental methods to accurately quantify the liquid transport in porous media in a time and space resolved manner.…”