A zero-VOC water-based epoxy topcoat has been formulated
Since 1982, when the first bisphenol A-based solid epoxy dispersion and modified amine system came to market as an adduct suitable for metal protection, water-based epoxy systems have been used for high-performance industrial primers and topcoats over metal due to their fast dry time, corrosion resistance, good pot life and low odor. Although water-based epoxy has successfully replaced traditional solvent-based epoxy/polyamide coatings in many high-performance industrial applications, the VOC content of these water-based epoxies is typically 200-350 g/L. So now, even though water-based, the usage of these coatings is increasingly limited by VOC regulations.
The technical challenge of developing low- to zero-VOC water-based epoxy is a difficult and complex task that involves attention to the total formulation and all of its compositional materials including resins, pigments and additives. Unfortunately, most water-based epoxy containing very low levels of solvent do not exhibit the same performance as do the heavy-duty solvent-based epoxies and high-VOC water-based epoxies. Major differences are evident in film formation and application properties.
A zero-VOC water-based epoxy topcoat has been formulated without aid of solvent, acid, diluent or plasticizer. It is based on a new innovative bisphenol-A “1”-type solid epoxy resin dispersion cured with modified amine. The new development offers high gloss, fast cure, long pot life and excellent resistance to water, humidity, chemical and corrosion on metal and concrete substrates. The performance properties of the new zero-VOC water-based epoxy topcoat are comparable to solvent-based epoxy/polyamide and high-VOC water-based epoxies.