8.6 Improving Surfactant Leaching of Architectural Latex and Paint Formulations
(Room 234-236)
10 Apr 18
12:00 PM
-
12:30 PM
Tracks:
Session 8: Measuring & Testing, Session 8: Measuring & Testing I
Improving the exterior durability of acrylic latex binders is one route to enhance the durability of a finished architectural paint. In addition to the paint formula, the binder can strongly impact exterior properties such as the dirt pickup resistance and surfactant leaching. Surfactant leaching occurs when freshly coated paints leach water-soluble components under humid drying conditions, leaving an undesirable residue and appearance on the surface of the dried coating. Evaluating paints for surfactant leaching is challenging due to the qualitative nature of most tests (i.e., visual observation and rating) or lack of precision (i.e., determination of surfactant leaching by weight). A newly developed analytical method that utilizes the sensitivity of Liquid Chromatography-Mass Spectroscopy (LC-MS) is able to quantify the extent of surfactant leaching between samples, providing higher resolution and granularity than simply by visual observation or by weight. Four resin composition factors (3 of which that are considered hydrophobic resin composition factors) were examined to look at the impact on surfactant leaching and dirt pickup resistance. Surprisingly, an experimental resin in the design with high levels of the 3 hydrophobic factors does not result in the best performance for surfactant leaching. Statistical modeling of the analytical test method identified main and interaction terms that drive surfactant leaching and showed a non-intuitive relationship between the factors, resulting in a determination coefficient (Rsquared) of 0.88 for the model. Comparatively, an analysis of the qualitative (visual) testing resulted in a poor statistical model (Rsquared = 0.38) that does not identify all active terms. In addition to the binder composition, the analytical method also allows for screening of paint formulation variables to determine quantitatively the active factors impacting surfactant leaching. Other performance properties were also analyzed in the context of the design, including dirt pickup resistance, tannin stain blocking, and performance on highly alkaline substrates (efflorescence), resulting in an optimized resin composition with a strong balance of exterior performance properties.