Carboxymethylcellulose acetate butyrate in water-based automotive paints

Water-dispersible carboxymethylcellulose acetate butyrate (CMCAB) has been shown to improve flow and levelling, and reduce cratering, picture framing, and other defects in water-borne paints. Rheology control agents which are normally used to keep pigments dispersed and to prevent sagging often increase elasticity of the paint. Fine-tuning the rheological profile of water-borne coatings is critical because too much elasticity can lead to major film defects while too little causes these 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 water-borne paints, CMCAB builds viscosity exponentially upon drying. This behaviour enhances flow and levelling and yet prevents sagging. Markets which may benefit from a water-borne cellulose ester include: automotive basecoats, topcoats, wood furnishings, pigment dispersions, and leather coatings.