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In zinc-rich primers Zn acts in the initial stage as sacrificial anode (cathodic protection). During lifetime Zn is transformed into its corrosion products, which seal the coating's pores (barrier protection). Such coatings are typically very highly pigmented which could cause the deterioration of cohesion and/or adhesion as well as mechanical properties. The formulations of different Zn pigments in epoxy matrices were developed with concentration of zinc particles reduced to about 50 wt% in the dry coatings. As Zn pigments were used: mixtures of zinc pigments with different particle size and particle shape (dust, flakes), zinc dust with organic surface treatment, zinc alloy pigments – ZnMg and ZnSn as well as Zn dust with an addition of graphene or carbon nanotubes. The mechanisms of protection by coatings with a reduced content of zinc pigments were studied in comparison with that of commercial zinc rich primers – epoxy and ethyl silicate – by the following methods: Scanning Kelvin Probe (SKP) detection of artificially inflicted samples after impact of salt spray test (SST), polarization experiments and EOC detections in combination with different corrosive impact, as well as by SST and the exposure to the natural marine environment (sea water splash zone). It was found that cathodic protection is shown by primer pigmented with Zn flakes, with zinc phosphate and barium sulphate addition as well as by primer containing Zn dust and graphene. They reach an open circuit potential (EOC) significantly below −0.86 V. Primers pigmented with ZnSn or Zn dust with an addition of carbon nanotubes (CNT) keep their EOC in the transition phase between −0.7 V and −0.86 V. Other primers with a reduced content of zinc pigments show only barrier protection. Coatings characterized by EOC in the range of cathodic protection or in the transition phase have very good protective properties in the corrosive environment. However, good anticorrosive properties were found also in the case of primers which do not show any cathodic protection, such as the primer pigmented with a mixture of Zn particles with different size and the primer containing Zn dust with chemical surface treatment. This shows that good anticorrosive properties can be obtained even if cathodic protection is not observed.

Facing recent controversial debates about commonly used epoxy resins in food contact applications, an understanding of newly developed polyester-based BPA-non-intent (BPA-NI) interior food can coatings is necessary. So far, little is known about the polymer structure of the polyester-based blends which have been brought to the European market. We report a detailed study on a polyester-phenol blend model system suitable for interior can coating in terms of its mechanical properties such as high flexibility, very good adhesion and hardness. We employ vibrational spectroscopy (FTIR), thermoanalysis (DSC) and an in-depth high-resolution solid-state 13C-NMR analysis to reveal that an overall homogeneity on molecular scale of the two main components in the blend is sustained in the solid state. This is remarkable, taking into account the overall different characteristics of polyesters and phenolic resins and explains the exceptional material properties of this coating.

Novel hyperbranched alkyd resins (HBAs) were synthesized by reacting the hydroxyl end-groups of the prepared hyperbranched polyesters, based on 1,3,5-tris(2-hydroxyethyl) cyanuric acid (THECA) as a trifunctional core, with different oil fatty acids, namely, linseed, soya and sunflower oil fatty acids. Resins of different compositions of HBAs were prepared by changing either the fatty acid or the generation of the hyperbranched polyester. Their molecular structures were identified using IR and 1 H and 13 C NMR spectroscopy. The thermal stability, glass transition temperatures and rheological properties were investigated. All of the alkyd resins exhibited initial decomposition temperature at values >300 °C. The decreased Tg values of LG3, SG3 and SFG3 render them suitable for use as coatings that are applied at ambient temperature. All HBAs show Newtonian behaviour and the viscosity was ranging between 1.2 and 5.2 Pa s. Film properties of the prepared alkyd resins using different driers were determined and it has been found that all samples exhibited good adhesion, bending, impact, ductility, and high gloss, but show low hardness.

An approach to modify the properties of UV curable polyurethane coatings by altering the amount and functionality of acrylic reactive diluents, in order to optimize the coating performance, is demonstrated. Based on the rheology analysis, a model of the rheological behavior of the UV curable materials depending on the amount and type of a reactive diluent in the composition is demonstrated in this study. The relationships between the rheological behavior, the mechanical properties and adhesion of the coatings prepared from polyurethane UV curable compositions containing different amounts and functionalities of acrylic reactive diluents, have been investigated and discussed in this study. Based on the results of the study, the desired properties of UV cured coatings can be modeled and controlled without changing the nature of a particularly selected oligomer, thus maintaining the advantages of its chemical structure in a coating composition.

Im Jahr 1867 gründete sich die Deutsche Chemische Gesellschaft, die ältere der beiden Vorgängerorganisationen der GDCh. Eine Fachstruktur der GDCh feiert ebenfalls Jubiläum: Vor 80 Jahren wurde die heutige Fachgruppe Lackchemie als Fachgruppe Körperfarben und Anstrichstoffe gegründet.

Barrier properties of packaging materials against moisture and oxygen penetration are of high relevance. Enhanced protection of existing materials against weather conditions can be achieved by application of printed coatings. To improve barrier performance of packaging materials, new inks for obtaining printed coatings with a layered structure were developed and investigated. The proposed ink compositions for flexographic printing on paper substrates are based on an environmentally friendly acrylic binder and contain inorganic fillers with platelet particles incorporated in the polymer matrix. Coatings based on the developed printing inks demonstrate significantly decreased water vapour permeability compared to traditional polymer inks. The effect of decreased permeability was investigated considering inks rheological behaviour, the coating structure, mechanical properties, surface energy and water uptake for different ink formulations. The developed inks provide variable optical properties including coatings with a relatively high transparency. The development of the functional barrier inks contributes to saving natural resources by prolonging life performance of packaging materials and goods.

In the European project MANIAC-Innovative Measurement Methodology in Quality Assessment of Coating, a methodology was developed to assess the long term durability of coatings. The project was focused on environmentally friendly waterborne automotive multi-layer coating systems. Although developed for waterborne coatings, the methodology is very generic and can be applied to all kinds of coatings. The first step in the evaluation of long-term performance of automotive coatings involves exposures to weathering (natural as well as artificial). Traditionally, the durability of coatings is evaluated by examining the changes in performance properties like gloss, color, and scratch resistance. In the MANIAC methodology, the focus is on changes in structures on molecular levels. Microtomed slices of the coatings were examined by FTIR spectroscopy for monitoring oxidation. UV spectroscopy and GC-MS were used to study the migration of additives like HALS and UVA. In the methodology, the environmental variables (outdoors as well as indoors), e.g., temperature, relative humidity, UV irradiation, were carefully monitored and included in the modeling scheme. The results from accelerated tests are modeled and, together with outdoor climatic data, the different models are used to predict degradation during outdoor exposure.