Formulation and performance study of low molecular weight, alkyd-based waterborne anticorrosive coating on mild steel

Abstract

A low molecular weight, alkyd-based waterborne anticorrosive coating was formulated using dimethylethanolamine (DMEA) as neutralizing medium, hexamethylmethoxymelamine (HMMM) as cross-linking agent, and para-toluene sulphonic acid (p-TSA) with certain additives. The coating was formulated with different mixing ratios of alkyd:HMMM (60:40, 70:30, and 80:20). Detailed investigation by FTIR and DSC studies revealed effective cross-linking and proper curing of the coating at the mixing ratio of 70:30. The coating was applied on pretreated cold rolled mild steel substrates by dip coating and was cured at 130 degrees C for 30 min. The performance of coated panels for corrosion resistance properties and mechanical properties were evaluated by exposing them to salt-spray, humidity and accelerated weathering and subjected to tests like flexibility, pencil hardness, adhesion and impact, respectively. Techniques like SEM/EDAX, AFM and FUR were used for detailed investigation of the coating before and after its exposure to the test environment. The results obtained confirmed the proper formulation and good performance of the developed coating. (C) 2007 Elsevier B.V. All rights reserved.