Structure and properties of polyurethane-based powder clear coatings systems modified with hydrotalcites

• Method of the modification of PU powder clear coatings by means of LDH was proposed.
• The formation of delaminated nanocomposites was confirmed by XRD analysis.
• Powder coatings containing LDH resulted in improved coating properties.
• The best properties were observed in coatings modified with Zn,Al-ALA LDH.

In this study, polyurethane powder clear coating systems consisting of polyester resin, blocked polyisocyanate and hydrotalcites (HT) intercalated with carbonate, aminododecanate, and ethylenediaminetetraacetate were examined. The blocked polyisocyanate crosslinkers for powder coatings were synthesized using trimethyhexamethylene diisocyanate (TMDI), formic acid, ε-caprolactam, dibutyltin dilaurate and triethylamine as catalysts. The powder coatings were investigated by atomic force microscopy (AFM) and X-ray diffraction analysis (XRD). The surface structure was correlated with the chemical structure of the coatings and macroscopic surface behavior: contact angle, surface free energy, gloss, elasticity, cupping, impact and scratch resistance, hardness as well as adhesion to steel surface.