Effects of the Acrylic Polyol Structure and the Selectivity of the Employed Catalyst on the Performance of Two-Component Aqueous Polyurethane Coatings

Two kinds of aqueous acrylic polyols (single step and multi step synthesis type) have been investigated for their performance in the two-component aqueous polyurethane application, by using more selective catalysts. The aliphatic polyfunctional isocyanates based on hexamethylen diisocyanates have been employed as suitable hardeners. The complex of zirconium, commercially known as K-KAT(®)XC-6212, and manganese (III) complexes with mixed ligands based on the derivative of maleic acid have been used as catalysts in this study. Both of the aqueous polyols give good results, in terms of application and hardness, when elevated temperatures and more selective catalysts are applied. A more selective catalyst promotes the reaction between the isocyanate and polyol component. This increases the percentage of urethane bonds and the degree of hardness in the films formed from the two components of aqueous polyurethane lacquers. The polyol based on the single step synthesis route is favourable concerning potlife and hardness. The obtained results show that the performance of the two-component aqueous polyurethane coatings depends on the polymer structure of the polyols as well as on the selectivity of the employed catalyst.