REDISPERSIBLE POLYMER POWDERS PREPARED FROM LOW CARBOXYLATION STYRENE BUTADIENE-BASED LATEX

摘要

A water redispersible polymer powder is produced by drying an aqueous mixture of a low carboxylation, low Tg, large average particle size water insoluble film-forming polymer latex or emulsion and a colloidal stabilizer. The latex polymer may have an average particle size of 2000.ANG. to 5,000.ANG., and an amount of carboxylation of 0.1% to 2.75% by weight of at least one ethylenically unsaturated dicarboxylic acid, salts or mixtures thereof, based upon the weight of the polymer. Dispersions containing the polymer and a polyvinyl alcohol as a colloidal stabilizer exhibit an unexpectedly low viscosity which facilitates spray drying and permits use of high solids content dispersions with low pressure spray drying to increase production efficiency. Cement compositions such as mortars, which contain the redispersible polymer powder exhibit unexpectedly lower rates of viscosity buildup for better workability or troweling, faster set time, and superior heat flow characteristics.