Self-stratifying epoxy/silicone coatings for plastics
The self-stratification is an eco-efficient process since it reduces solvent emission, time of implementation and labor cost. Moreover, it could lead to the development of a large range of new products for extensive application fields. For self-stratification to occur, liquid coatings must contain at least two incompatible resins, giving rise in “one pot” to a two-phases mixture after the formation of the solid film.
Pigments have no negative effect on stratification
The perfect self-stratification of this polycarbonate system was evidenced by microscopic analysis coupled with X-ray mappings. The influence of solvents and a curing agent on the stratification process has been investigated. It is shown that the system diluted in butylacetate:xylene (at a 1:1 ratio) leads to the best stratification pattern, with the silicone phase located on the top of the coating. Three pigments (red iron oxide, calcium carbonate and zinc phosphate) were also incorporated in this epoxy/silicone system. They do not affect stratification, whereas visual appearance and adhesion are strongly dependent on the phase in which pigments are dispersed, as well as on the solvent used.
The study is published in: Progress in Organic Coatings, Volume 103, February 2017, Pages 101–110