The impact of rheological modifiers on water-borne coatings

While low volatile organic components (VOC) architectural coatings like int erior wall or exterior facade paints are accepted to a large extent by the end-users, conventional solvent based alkyds are dominating in the area of high performance laquers. The lower acceptance of water-borne coatings corr esponds to aesthetic problems like lower gloss, poorer how and leveling as well as application disadvantages like shorter open-time, lower brush drag and limited weather conditions. To solve these problems it is mandatory to understand dispersions theology and the different ways to adjust theologica l properties of water-borne paints and laquers by special modifiers. In thi s paper a short review is given about the thickening mechanisms of three ma in groups of theological modifiers (cellulose ethers HEC and HMHEC, acrylic s ASE and HASE, and urethanes HEUR) in the presence of an acrylic and a pol yurethane dispersion. Furthermore measurements on two model coatings are pr esented. These results allow a discussion about several factors which influ ence the coatings theology and performance. (C) 2001 Elsevier Science B.V. All rights reserved.