Improved anticorrosion properties of polyurethane coatings based on high-solids acrylics synthesized in a high pressure reactor

High-solids styrene-hydroxyl-acrylic copolymer resins were synthesized in different solvents above their boiling points in a high-pressure reactor and compared to the same resin synthesized at ambient pressure. High-solids acrylics, prepared in a closed high pressure reactor at temperature above solvent's boiling point, have lower molecular weight, narrower molecular weight distribution and consequently a lower viscosity compared to resins with the same chemical composition and content of solids prepared at ambient pressure. Syntheses were monitored calorimetrically and by in situ ATR-FTIR spectroscopy using an RC1e™ reaction calorimeter. All synthesized resins were tested in two-component polyurethane metal topcoats. Coatings based on resins synthesized in a pressure reactor cure faster according to Model Free Kinetics studies and display improved anticorrosion properties, determined by electrochemical impedance spectroscopy, when compared to the resin synthesized at ambient pressure.