The application of liquid crystalline epoxy resin for forming hybrid powder coatings

The purpose of the study was to check whether the addition of a liquid crystalline epoxy resin containing rigid mesogenic groups would have a positive effect on the properties of epoxy/polyester hybrid powder coating. The research included the preparation of three hybrid compositions of epoxy/polyester powder coating consisting of polyester resin GS 7371 with the addition of commercial bisphenol A-based epoxy resin E 011 (Composition 1), mixture of epoxy resin E 011 and liquid crystalline diepoxy resin MU22 (Composition 2) and only liquid crystalline diepoxy resin MU22 (Composition 3). By using the DSC method, the course of the cross-linking process of the prepared compositions was analyzed, and the curing conditions were selected. Based on the DSC analysis, it was also found that the addition of diepoxide MU22 reduces the glass transition temperature of the obtained coatings. For coatings cured on a steel substrate, a number of tests were carried out on the basis of which the surface structure was correlated with the chemical structure of the coatings and macroscopic surface behavior, i.e.: color, thickness, gloss, roughness, abrasion and scratch resistance, hardness, elasticity, contact angle, surface free energy, as well as adhesion to steel surface. It has been found that the modification of polyester/epoxy hybrid powder paint with liquid crystalline epoxy resin had a positive effect on its properties.