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Influences of surface energy and kinetics on adhesion of polyester powder coatings on anodized aluminium

: Englert, Cornelia; Christ, Ulrich

Vincentz Network GmbH & Co. KG, Hannover; u.a.:
EC European Coatings Congress. Proceedings : Nuremberg, Germany, 18 + 19 March 2013
Hannover: Vincentz, 2013
2 pp.
European Coatings Congress <2013, Nürnberg>
European Coatings Show <2013, Nürnberg>
Conference Paper
Fraunhofer IPA ()
Chemische Kinetik; powder coating; Pulverbeschichten; Polyester; Adhäsion

Studies of the influence parameters of the powder coating and the substrate surface on the one hand and the overall system characteristics on the other hand could show their relation to the wet adhesion of polyester powder coatings according to the GSB water boiling test. At this there were found the following properties as important variables and characteristics related to the adhesion. An important characteristic is the melt viscosity, where it is useful to define a "flow window" and to discuss this in connection with the surface tension. In addition it was also important to examine the reduction of the glass transition temperature by the exposure to water. The reversible work of adhesion should be considered too, for it has proven to be a good measure to describe adhesion phenomena. The surface tension of the melted powder coating and the substrate should be determined with their dispersive and polar fractions. High dispersive fractions are an advantage for a good adhesion. The influence of barrier properties, like water vapor permeability and water absorption on the wet adhesion of the coatings, were investigated. Additionally it is important to achieve a homogeneous interface structure resp. a strong interfacial contact between the substrate and the powder coating. This was determined by SEM images.