The binders used in water-based paints are traditionally produced by emulsion polymerization. These binders are typically acrylic, styrene-acrylic or vinyl acetate based oil-in-water emulsion (dispersion) polymers.
One important property of polymer binders is their pigment binding capacity (PBC). The PBC of a polymer binder is reflected in the abrasion resistance the binder imparts to a paint film. This property can be tested with a standard wet scrub resistance test.1 The use of binders with high PBC allows for the formulation of water-based paints at relatively high pigment volume concentration (PVC) i.e., 45-55 weight percent (wt%) of the total formulation mass, with an 8-10 wt% binder composition. The use of such binders gives a cost reduction in the resultant paint, as binders are generally more expensive than extenders (calcium carbonate, talc).2 The PBC of emulsion binders can be adjusted by the type and amount of the auxiliary monomer (e.g., methacrylic acid (MAA) or acrylic acid (AA)).3 The role of the auxiliary monomer in an emulsion system is twofold: (a) it enables latex stability and (b) facilitates pigment wetting/binding.4