Influence of the Interaction Between Pigment and Various Cobinders on Rheology, Dewatering and Coating Performance, 1991 Coating Conference Proceedings

The influence of the interaction between pigment (English clay) and various cobinders (PVOH, CMC, starch and synthetic thickeners) on rheology, dewatering, runnability and paper properties has been studied. Rheological measurements were made over a wide shear range including interaction studies at small deformations. The rheological behavior of the colors was found to be highly dependent on the choice of cobinder, indicating that the interaction between pigment and different cobinders causes formation of aggregates which differ in nature and in strength to withstand shear forces. Simultaneously considering the laboratory dewatering and rheological data proved to be helpful in explaining differences in high speed blade runnability on a pilot coater. The formation of strong aggregates in a color appears to have a negative influence on runnability. Some of the properties of the coated papers could be correlated to the coating color parameters studied in the laboratory.