ADSORPTION STUDIES OF ASSOCIATIVE INTERACTIONS BETWEEN THICKENER AND PIGMENT PARTICLES

Adsorption of a HEUR thickener and a HMHEC thickener have been studied on two titanium dioxide pigment grades with and without dispersant pr eviously adsorbed. One of the pigments had an acidic surface, mainly s ilica, and the other a more basic alumina/zirconia surface, Both assoc iative thickeners adsorbed on pigments having a partially hydrophobic (a-olefinic-maleic acid co-polymer) dispersant preadsorbed on the surf ace. No adsorption rakes place when sodium hexametaphosphate, a highly charged low molecular weight inorganic dispersant, was used, The alph a-olefinic-maleic acid co-polymer dispersant is shown to adsorb on a n egatively charged silica surface. This is assigned to hydrogen bonding between unionised carboxylic groups from the dispersant and oxide ion s on the pigment surface. (C) 1997 Elsevier Science S.A.