Structural Effects of Co-Binders on the Color Rheology and on the Surface Properties of Coatings, 1993 Coating Conference Proceedings

Can Vu

Claude Trouve

The rheology given by several synthetic water-compatible co-binders is evaluated in this study with colors containing kaolin clay and calcium carbonate. The co-binders mainly differ from their cross-linking state. Through swelling measurements, it is attempted to relate the cross-linking state of the co-binders to the rheological properties of the color formulations. Different tests were used to characterize the colors: the shear and the capillary flow tests simulate the color reaction during the coating process while the oscillatory tests are used to follow the structure recovery kinetics. The cross-linked structure of the micro particles constituting the co-binder limits their interactions with the different species in the formulation. The coating structure is mainly governed by the co-binder water absorption or desorption kinetics. The color recovers almost immediately its structure beyond the blade. The swollen micro particles, on drying, create micro voids. The resulting coating is bulky, smooth and presents a good fibre coverage.