Polymer Binders of Flame-Retardant Intumescent Coatings

This chapter presents the results of review and comparison of contributions made by film formers of intumescent composition, which initially forms a fire-retardant coating. Based on a critical analysis of literature and experimental data, it is shown that the nature of polymer binder has a direct effect on the fire-retardant efficiency of the intumescent coating. It has been shown that it performs a number of significant functions: the binder is a matrix in which the components of flame-retardant composition and target additives are uniformly distributed; it ensures adhesion of initial coating to protected substrate, and is involved in the formation of structures catalytically active in intumescent process. In this chapter, the authors answer the question of why homopolymers and copolymers of vinyl acetate with ethylene, dibutyl maleate, vinyl chloride, esters of branched carboxylic acids and others are most widely used as binders for intumescent compositions. As part of consideration of conditions of applicability of film formers of various nature to create effective flame-retardant compositions, the results of comparative thermal tests of various intumescent coatings are presented. It is shown that the most suitable for intumescent systems are film formers that are sensitive to heat and capable of forming carbocyclic structures upon thermolysis. The occurrence of catalytically active polymer carbon clusters with a graphite-like structure during the thermal degradation of certain polymer binder has been experimentally proved. The expediency of using polyvinyl alcohol and its polymer analogs as binders in intumescent compositions, which have optimal decomposition temperatures and form thermolysis regions of local ordering of aromatic structures of polymer carbon, is substantiated.