This presentation will focus on how specially designed "Color Viscosity Stabilizers" control the "viscosity drop" in waterborne paints tinted with Universal colorants.Typically, synthetic thickeners are very useful for defining the rheology of waterborne latex paints. These materials include hydrophobically modified ether-urethane polymers (HEUR), hydrophobically modified poly-ether-polyols (PEPO), and hydrophobically modified alkali swellable emulsions (HASE). Paints made with these synthetic thickeners show excellent performance in flow and leveling, moisture resistance, spatter resistance and coverage. One of the most difficult problems to deal with when using associative thickeners has been the viscosity instability upon the addition of colorants. This phenomenon which is well known in the industry as "viscosity drop", results in poor coating properties and increased formulation complexity. The major components responsible for the observed viscosity drop are the surfactants used in the colorants. Not all surfactants, however, produce a viscosity drop, nor are the observed viscosity changes a simple function of the surfactant concentration. The viscosity drop is caused by the over-abundance of traditional surfactants used to make Universal Point of Sale colorants. The viscosity drop is different for each colorant in the Universal colorant line because these colorants were developed with different surfactant packages. We have developed a new line of products that can control the viscosity loss in latex paints. These additives, while not primary viscosifiers themselves, will limit viscosity loss to less than 10 Krebs Units (KU) in a properly formulated paint. Further advantages have been seen in providing balanced sag and flow & leveling without impacting all other paint properties.
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