New activated low zinc epoxy primers

 
Coating standards such as SSPC-Paint 20 and ISO 12944 demand that zinc-rich coatings contain at least 65% and 80% zinc dust by weight in the final dry film, respectively. Traditional zinc rich primers need this high zinc loading to achieve galvanic protection of steel. However, new technology allows us to develop; for the first time; zinc primers with a lower weight percentage of zinc and still provide similar or better corrosion protection to the steel. This paper will examine the formulation and performance of new, activated zinc epoxy primers compared to conventional zinc rich epoxy primers. We will demonstrate comparable corrosion resistance at reduced zinc levels in the dried film and show that zinc metal levels can be reduced to as low as 40% by weight without compromising galvanic corrosion protection: some primers resisted 2000 hours of Salt Spray Test (ISO 9227) with a rust creep below 1.5 mm.