Paint formulation - Physical chemistry and powdered materials

The aim of this article is by no means to provide standard manufacturing formulations, but rather to show how it is possible to approach the design of paint formulations based on the mastery of physical quantities and knowledge of raw materials. Paints must meet the needs of end-users and be suitable for protecting and/or decorating surfaces. This is why, depending on their intended use, paints will be formulated differently. Their specificity will essentially depend on their field of use: decorative "building" and "consumer" paints, anti-corrosion paints, industrial paints, marine paints. Physical chemistry is involved at every stage of a paint's life: manufacture, application, conservation, adhesion to the substrate, drying, appearance and degradation. Thus, pigment concentration by volume is considered the fundamental parameter in paint formulation optimization. In addition, it is important to understand the limits of simple viscosity measurements, and to study the rheological behavior of ready-to-use products in order to avoid defects such as drips. Hildebrand's work, based on enthalpy of mixing, complemented by Hansen's, enables us to predict the behavior of solvent/polymer combinations using solubility parameters. Similarly, the notion of wettability, proposed as early as 1805 by Young, is also applied to paint spreading.

All this information will show that the development of a paint formulation is more a question of fundamental knowledge of physical chemistry than of "cooking recipes". The second part will deal more specifically with the polymers used in the formulation (alkyd resins, epoxies, etc.), as well as their properties and applications.

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