Organic coatings are the most widely used finishing for all kinds of structures. In this chapter, a brief presentation of organic coatings and of its properties is made, dealing namely with the components and their role in the coating performance, the properties of the dry coating, the degradation mechanisms and finally the specific properties for coatings designed for various substrates. The chapter is meant to provide non-experts with a general look over the world of organic coatings.
Organic coatings • Polymeric materials • Weathering • Pigments • Binder • Curing • Adhesion • Dispersion • Pigment volume concentration • Chalking • Volatile components (of an organic coating) • ZETA potential • Acid pollutants • Gloss • Cracking
Most objects and surfaces that surround us are covered by a finishing layer, commonly with a composition different from the base material and which in some way improves the aptitude of the object or surface to its final use. Coatings can be metallic (like galvanized steel, in which steel is coated with zinc), inorganic non-metallic (like anodized aluminium, in which the base metal undergoes chemical conversion at the surface, producing a protective layer of aluminium oxide) or organic. This last group, which includes paints and varnishes, is used in practically
A. Simoes (H)
Department of Chemical Engineering—DEQ and Centro de Quimica Estrutural, Instituto Superior Tecnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisbon, Portugal e-mail: alda. simoes@tecnico. ulisboa. pt
© Springer International Publishing Switzerland 2015
M. C. Gonsalves, F. Margarido (eds.), Materials for Construction and Civil
Engineering, DOI 10.1007/978-3-319-08236-3_17
all types of applications, from the automotive industry, to aeronautics, to furniture
Whatever the application, organic coatings always perform several functions:
• Protective function: the coating is a barrier that separates the surface from the outer environment, increasing its resistance to air, water, solvents (organic liquids) and chemically aggressive liquids (acid or alkaline).
• Decorative function: it is reached by means of colour, texture and brightness.
• Hygienic function: on walls and pavements, and also in other applications, such as furniture, the organic coating, by decreasing the roughness of the surface and also by changing its composition, can decrease its tendency to accumulate bacteria, dirt and other impurities, thus easing the cleaning processes.
• Impermeabilization: this is a particular case of the protective function. Organic coatings constitute a barrier to the outer environment, thus isolating the material from the outer humidity; further, they tend to fill the recessed areas or cracks on the surface, further protecting from the effects of water.