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 previously adsorbed. One of the pigments had an acidic surface, mainly silica, and the other a more basic alumina/zirconia surface. Both associative thickeners adsorbed on pigments having a partially hydrophobic (alpha-olefinic maleic acid co-polymer) dispersant preadsorbed on the surface. No adsorption takes place when sodiumhexametaphosphate, a highly charged low molecular weight inorganic dispersant, was used. The alpha-olefinic-maleic acid co-polymer dispersant is shown to adsorb on a negatively charged silica surface. This is assigned to hydrogen bonding between unionised carboxylic groups from the dispersant and oxide ions on the pigment surface.

Nyckelord

Thickeners

pigments

surface adsorption

dispersants

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