Pigment Binding of Alkyd Latex Polymers

By Jeffrey H. Danneman

Alkyd polymers provided as a latex are a recent and commercially viable alternative to the more traditional solutions in organic solvents. Replacing the organic solvent with water provides coatings that have exceptionally low volatile organic compounds (VOCs) while maintaining the traditional benefits of alkyds including high gloss, adhesion, and—as is the subject of this paper—very high pigment loading capacity.

Reichhold has previously presented research describing the polymer design and coating formulation of alkyd latex direct-to-metal primers. In a continuation of that research, we explore the pigment binding capacity of alkyd latex polymer performance as measured by both wet-cup and dry-cup permeability and with electrical conduc-tance.

These techniques clearly define the critical point for several extender pigment combinations and are used to maximize corrosion and humidity resistance in metal primer formulations with a reduced pigment volume concentration (PVC) approaching 82%. In highly filled traffic paint formulations where the reduced PVC may reach 90%, these techniques are used to compare alkyd and acrylic latex polymers, with the data further demonstrating the exceptional pigment binding capacity of the alkyd.