Additives Influencing the Properties and Processing of the Coating Color
It is desirable that coating colors have moderate pseudoplastic, shear thinning flow behavior. Too drastic shear thinning can cause excessive water penetration into the base paper and, accordingly, loss of binder. To adjust the rheological properties and water retention of a coating color, synthetic co-binders and thickeners are used.
They have a profound effect on the runnability of a coating color, and hence of the coating machine, on account of their thickening action, their characteristic rheol¬ogy at different shear rates, and their water retention. The mechanisms for dissolv¬ing, thickening, water retention, and rheology of synthetic co-binders are very complex.