Reduction of zinc and volatile organic solvents in two-pack anti- corrosive primers, a pilot study

Abstract

For decades one of the directions to obtain anti-corrosive properties of coatings in the protective coating industry has been the use of zinc as an active pigment in the primer layer. However due to strengthening of environmental legislation the use of this metal has become an item of discussion. In addition due to the nature of the traditional low solid zinc containing formulations, formulated close to critical pigment volume concentration (PVC), it proved to be difficult to develop very high solids zinc containing formulations with comparable performance. At the moment the product range of our company contains both zinc containing and zinc free two-pack primers. Examples from both generic types have excellent track records. To determine the position of the zinc free primers in relation to the zinc containing ones a comparison study was initiated. A new high solids two-pack epoxy primer was included in this test program to check whether a solvent reduction in this range of products was feasible. In this paper the results of the comparison between a zinc epoxy primer, a zinc free epoxy primer and a high solids version of the zinc free epoxy primer, some formulation aspects and the consequences for the future will be discussed.