TABLE OF CONTENTS W.A.E. DUNK
A fully formulated paint is a complex system which comprises pigments and a variety of additives that vary with the final demands of the coating. These components are dispersed in a fluid continuous phase that may be aqueous or non-aqueous, and which contains a polymer either as a solute or as a colloidal dispersion. This continuous phase is known as the binder and largely determines the character of the coating. It should, however, be emphasised that although solvent-based coatings are still used, the increasing attention to environmental preservation by health and safety agencies has led to an important growth in the development and adoption of water-based resins ( cf. Chapter 2). As a consequence of the shift in emphasis, this chapter will give preferential attention to those techniques that are solvent free, or confine their use to a minimum. Thus non-aqueous dispersions are considered briefly in view of theoretical background concerning colloid stabilisation that can be applied to aqueous environments. More emphasis will be placed on emulsion polymerisation and its ability to exercise morphological and particle shape control of film-forming polymers.
A colloid may be defined as any material that contains a physical boundary dimension in the range of 1 1000 nm. When the upper bound is exceeded, a suspension is formed that quickly settles under gravity: a colloidal dispersion is not so affected. When considering colloidal dispersions, it is important to differentiate between those in which the disperse phase is...
