| abstract |
The invention provides a dispersant for an aqueous dispersion of positively charged or chargeable solid particulates which comprises a compound having an anchoring moiety linked to a polymeric hydrophilic moiety, the anchoring moiety containing at least one acid and/or hydroxy group and having an overall acidity or neutrality and the polymeric moiety having a lower affinity for the particulate surface than the anchoring moiety. The anchoring moiety preferably contains at least two acid groups, preferably carboxylic acid groups, attached either in a [1,1], [1,2] or [1,3] relationship and is linked to the polymeric moiety, which is preferably derived from acrylamide or methacrylamide monomer units, preferably by a sulfur atom. The dispersant can reduce the viscosity of an aqueous dispersion of positively charged or chargeable solid particulates and can reduce the tendency of the resulting dispersion to form a gel or a yield stress material. The dispersant facilitates the processing of the resulting compositions in manufacturing operations and it may be used, for example, as a component of a coating material, a ceramic, paint, refractory material, filler or in an inkjet recording paper or film. Additionally, the dispersant can allow the use of higher concentrations of solid particulates and enable control of the yield stress, as some yield is often beneficial in helping prevent or reduce sedimentation. |