The rheological properties of paper coating suspension and its application. Part 1: the influence of solid content and ionic strength on flow properties

The rheological properties of coating suspensions containing a blend of clay and CaCO3 as a pigment have been evaluated at 22°C, using a rheometer with shear rates from 0.5 to 100rpm. The state of dispersion of the pigment, the structure viscosity of the suspension as a result of pigment‐pigment or pigment‐binder interactions, and its behaviour by changing the solid content and ionic strength, were limited from the examination of the flow curves. The flow parameters for each suspension were calculated. The results showed that changes in solid content and ionic strength by the addition of divalent simple electrolyte (CaCl2) and pH level have a more profound effect on the flow parameters than that obtained by the addition of monovalent simple electrolyte (NaCl) or polyelectrolyte soluble polymers (CMC) with different degrees of substitution. The type of acid used to adjust the pH of the suspension also has a great influence on the flow parameters.