As the industry shifts to higher solids coatings (more than 90%) the rheological additives do not disperse as easily as before. The performance of the organoclay starts to drop off as there is less solvent in which the clay can disperse. The best products are the polyamide and polyamide/castor blends, which give both the highest viscosity and sag resistance. Castor wax and Castor wax/amide blends both work well in high solids but require active heating and cooling in manufacture, which makes them hard to use in large scale paint manufacture. Polyamide pastes are used as post products but contain high levels of solvent. Polyamides are the organic products that are typically used in high solids coatings. They do require heat to activate but can be packed out hot. Their hydrogen bond will break upon shear (spray) and immediately reform upon removal of shear. Polyamides are the key choice to provide rheological properties for marine and protective coatings. At the same time the lack of solvent has negative effects on the polyamide. The new range of organic thixotropes specifically for high solids has shown that it can work in a low solvent environment and give excellent sag resistance and show no impact on inter coat adhesion.
New advances in rheological performance in high solids marine and protective coatings
Neue Fortschritte bei der rheologischen Leistungsfähigkeit von Schutzbeschichtungen für Seewasseranwendungen mit hohem Feststoffgehalt
PPCJ Polymers Paint Colour Journal ; 204 , 4597 ; 28-31
2014
3 Seiten, Bilder, Tabellen
Aufsatz (Zeitschrift)
Englisch
Protective coatings for ships and marine installations
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