Associative behavior of hydrophobically modified hydroxyethyl celluloses (HMHECs) in waterborne coatings

The associative behavior of hydrophobically modified hydroxyethyl cellulose (HMHEC) in polymer dispersions has been determined as a function of the composition of both the associative thickener (AT) and the latex. How changes in interaction between HMHEC and the latex influence the rheology of the latex thickener systems is discussed. Adsorption of HMHECs onto an acrylic emulsion strongly depends on the hydrophobe type and degree of substitution, as well as on the molecular weight of the associative thickener. The degree of latex adsorption is influenced dramatically by the stabilization system utilized, that is choice and level of surfactant and carboxylic acid content, in addition to the composition of the monomer mix. Rheological measurements demonstrate that HMHECs of specific composition can provide gloss emulsion paints with a balance of rheological properties, combining excellent levelling with sag resistance.