High solids copolymer dispersion from a latex and its use in sealants

摘要

A method for polymerizing at least one unsaturated monomer in the presence of a latex results in a high solids dispersion of polymer particles with lower viscosities than traditionally observed. A significant wt. % of the polymer from added monomers can be present in large particles, having nonspherical shapes. Some of the original latex particles are retained during the polymerization and these increase the solids content and lower the viscosity by packing in the interstices between large particles. The total polymer solids content can easily be varied from 70 to 92 or more wt. %. The viscosities at very high solids contents become paste-like but the materials still are stable to storage and further handling without causing the dispersion to separate into an agglomerated polymer portion and released water. The dispersions are useful to form sealants, membranes, etc., either with or without other additives. A preferred use is as an acrylate water-based caulking compound where the high solids and thixotropy of the dispersion allows for formation of a water-based caulk with low shrinkage.