New regulations, increased awareness, and the importance of environmental stewardship have led to a strongly increased demand for waterborne (WB) protective topcoats. However, matching the performance of solventborne (SB) two-component (2K) polyurethanes remains a challenge for resin and paint producers. Synthesis and formulation of primary or secondary dispersions are not straightforward.
For secondary dispersions, the removal of solvents from polyols prior to dispersion in water is technically challenging. The emulsion polymerization process producing primary dispersions often faces problems of water-phase homopolymerization of the hydroxyl monomers, resulting in a poor stability of the emulsions, high process grit, and insufficient crosslinking of the final coatings.