POLYMER, COMPOSITION AND USE

摘要

There is described a solvent assisted dispersion (SAD) process for preparing an aqueous polycondensate (such as a polyester e.g. uralkyd) dispersion substantially free of solvents, comprising the steps of (a) reacting in a non-protic solvent a mixture of (i) one or more polycondensate monomers, oligomers and/or polymers comprising a plurality of isocyanate-reactive groups; wherein the monomers, oligomers and/or polymers comprises at least 2% by weight (components) of a fully, partially or non-neutralized acid group having a pKa less than 3 (ii) at least one multifunctional isocyanate, to form a mixture of a first (e.g. uralkyd) emulsifier resin and the non-protic solvent; (b) optionally, reacting the first emulsifier resin from step (a) with at least one monomer, oligomer and/or polymer different from component (a) (performance polymer) to form a second (e.g. uralkyd) resin; (c) dispersing the first emulsifier resin from step (a) and/or the second performance resin from step (b) in an aqueous medium to form an aqueous (e.g. uralkyd) dispersion. (d) removing substantially all of the non-protic solvent from the dispersion to form a (e.g. uralkyd) dispersion substantially-free of solvent.