Carboxymethylcellulose Acetate Butyrate: New Cellulose Ester Additive for Waterborne Coatings

摘要

Water dispersible carboxymethylcellulose acetate butyrate (CMCAB) improves flow and leveling, and reduces cratering, picture framing, and other defects in waterborne paints. The use of rheology control agents to keep pigments dispersed prevent sagging, and enable shear thinning through spray nozzles often increase elasticity of the paint. Fine-tuning of the rheological profile is critical, because too much elasticity can lead to major film defects. Too little elasticity cause waterborne coatings to drip off the surface. By adding CMCAB along with the other rheology modifiers, the viscous/elastic moduli can be controlled without detrimentally affecting other properties. Unlike other Newtonian thickeners for waterborne paints, CMCAB builds viscosity exponentially upon drying. This enhances flow and leveling and yet prevents sagging. Markets, which would benefit from a waterborne cellulose ester, include automotive basecoats, topcoats, wood furnishings, pigment dispersions, and leather coatings.