Novel Acrylic Epoxy Hybrid System Design for Metal Protection Application

By Zhigang Hua, Hunter Shu, Allen Xu, Barry Zheng, Aaron Yang, Zhenwen Fu, Andrew Hejl, Henry Eichman, Kiran Baikerikar

A process for producing a novel acrylic epoxy hybrid (AEH) is demonstrated in which a small molecule epoxy diffuses from its “monomer” droplets through the aqueous phase and into an acrylic dispersion particle. The obtained hybrid can be formulated as a viscosity-stable 2K coating system by mixing pigments and fillers with waterborne polyamine hardener as Part A and the acrylic epoxy hybrid as Part B.

The 2K coating formulation stability is controlled by the hybrid and hardener surface charge reflected in zeta potential values. When the zeta potentials of the hybrid and hardener were in the range at │ζAEH + ζhardener│< 30, the 2K coating formulation showed instability and a tendency to form gel.

The 2K coating system performance relies heavily on hardener choice for metal protection properties such as salt spray corrosion resistance. It was found that water solubility of hardener is negatively correlated to salt spray resistance (SSR). With an appropriately low water solubility hydrophobic hardener, the 2K coating system can achieve ≥ 600 hr SSR, which is much better than a 1K acrylic and 2K acrylic/liquid epoxy resin (LER) system and similar or slightly worse than a conventional 2K waterborne epoxy system.

Furthermore, the 2K coating system dries faster than a traditional 2K WB epoxy system but has much longer pot life. In addition, its application properties, such as dilution stability, are also excellent due to the better stability of the acrylic latex polymers.