The system consists of a thermosetting polymer, based on a hydroxyl-containing acrylic and a butylated melamine-formaldehyde resin, cured in the presence of a thermoplastic polymer.
Nonpigmented, opaque coatings are based on microporous films for which the term "pittmentized" is proposed. A method of preparation and the type of compositions used is discussed in detail. The system consists of a thermosetting polymer, based on a hydroxyl-containing acrylic and a butylated melamine-formaldehyde resin, cured in the presence of a thermoplastic polymer. Though completely ... [Show full abstract] compatible in solution, the system, after curing, gives rise to a two-phase composition consisting of a cross-linked matrix and the thermoplastic polymer dispersed throughout the matrix in the form of microglobules or channels. The thermoplastic polymer is then extracted from the matrix and the film is dried to give an opaque pittmentized coating. Such coatings are discussed in terms of property dependence on composition, microvoid volume concentration, reinforcement with white and colored pigments, and other variables. Other functionalities for pittmentized coatings are described.