ASSOCIATIVE BEHAVIOR OF HYDROPHOBICALLY-MODIFIED HYDROXYETHYL CELLULOSES (HMHECS) IN WATERBORNE COATINGS

The associative behavior of hydrophobically modified hydroxyethyl cell ulose (HMHEC) in polymer dispersions has been determined as a function of the composition of both the associative thickener (AT) and the lat ex. How changes in interaction between HMHEC and the latex influence t he rheology of the latex thickener systems is discussed. Adsorption of HMHECs onto an acrylic emulsion strongly depends on the hydrophobe ty pe and degree of substitution, as well as on the molecular weight of t he 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 c omposition of the monomer mix. Rheological measurements demonstrate th at HMHECs of specific composition can provide gloss emulsion paints wi th a balance of rheological properties, combining excellent levelling with sag resistance.