New CNSL-based water-borne curing agents for low VOC Zn-rich primer and protective epoxy primer

 
Novel WB epoxy curing agents have been developed based on Cashew NutShell Liquid (CNSL), a natural and renewable biomaterial. These materials have inherited unique properties of CNSL such as fast cure, excellent adhesion and good compatibility with various epoxy resins which enable the formulation of low VOC and high performance protective coatings. This paper will present two formulation and performance studies. 1) Low VOC (<100 g/L) WB Zn-rich primers: they are formulated with standard liquid epoxy resin and show excellent flexibility and good adhesion to substrates. Superb anti-corrosion performances are observed on single-coat system after 2000 hours Q-Fog exposure. Furthermore, the uses of graphene in WB Zn-rich primers are investigated. 2) Low VOC (<80 g/L) primers: they are formulated with solid epoxy dispersions and exhibit long pot-lives, fast cure and good adhesions to various substrates. Lastly, long-term anti-corrosion results for the combined WB Zn-rich primer and WB epoxy primer system are discussed.