Anti-corrosive zinc primer coating compositions

An anticorrosive coating composition comprising:

• a) an epoxy-based binder system in an amount of 25-50% by solids volume of the coating composition, wherein the epoxy-based binder system comprises one or more curing agents selected from compounds comprising at least two reactive hydrogen atoms linked to nitrogen, and
• wherein said curing agent is selected from amines or amino functional polymers selected from aliphatic amines, cycloaliphatic amines, polyamidoamines, polyoxyalkylene amines, aminated polyalkoxyethers, alkylene amines, aralkylamines, Mannich bases, amino functional silicones or silanes and including amine adducts and derivatives thereof,
• b) zinc particles having a content of zinc of at least 90% by weight, wherein the zinc particles are present in the coating composition in an amount of about 20-35% by solids volume,
• c) microspheres present in an amount of between about 15-25% by solids volume of the coating composition, and
• d) a conductive pigment, wherein the conductive pigment is graphite,
• wherein said microspheres are of spheroidal shape and made of silica alumina ceramics, and wherein said microspheres have a true density of about 0.6 to 2.8 g/cc, and
• wherein the D50 is in the range of about 13 to 80 μm, and
• with the proviso that said coating composition does not comprise hollow glass microspheres, and
• wherein said conductive pigment is present in an amount of between about 1.0 to 3.0% by solids volume of the coating composition, and
• wherein a solids volume ratio of the microspheres to conductive pigment is in the range of 5:1 to 20:1, and
• wherein the epoxy-based binder system is solvent-borne or water-borne epoxy resin based.