Modification of rheological properties of a solventborne paint using additives

Abstract

The application properties of paints such as spreading and levelling properties, film thickness, sedimentation tendency and pigment stability are determined by the paint rheological behaviour. Sufficiently shear thinning, thixotropic paints with a yield point have, as a rule, suitable application properties. If the paint does not exhibit the required properties, its rheological behaviour may be improved using a proper type of rheological additive. In this work, the rheological properties of an acrylic paint (dispersion of TiO2 in a solution of acrylate copolymers), which behaves as a Newtonian liquid, have been modified using three different types of commercial additives. To evaluate the influence of additive adjuction, the flow curves, yield point, oscillation tests, and creep and recovery tests have been measured for the paint samples on the dynamic rheometer RS 150(Haake). It has been found out that the modified paints show shear thinning behaviour with a yield point and thixotropy. At the same time, they behave as viscoelastic liquids with different portion of elastic component of deformation at shear stresses in the vicinity of the yield point. The additive Byk 410 has been evaluated as the most efficient type of rheological additive. Its addition to the basic paint is easy and the paint samples modified with this additive exhibit the most suitable rheological properties.