Patent ID: 6835459
Filing Date: 2004-12-28
Classification: C09D,C23C,Y10S,Y10T

Abstract:
A process for coating a metal object with an electrically conductive coating, said process comprising successively applying the following layers to at least part of the surface of the metal object:a) chemical conversion layer; b) 1 to 10 &mgr;m thick electrically conductive organic layer containing at least one organic binder and at least one electrically conductive substance in powder form; c) 70 to 120 &mgr;m thick powder coaling layer; wherein the conductive organic layer b) is obtained by applying a coating composition of (A) or (B); said composition (A) comprising i) 10 to 30% by weight of an organic binder which cures at a temperature of 140 to 159Â° C. and preferably at a temperature of 149 to 159Â°; ii) 30 to 60% by weight of at least one electrically conductive substance in powder form, selected from zinc, aluminium, graphite, molybdenum sulfide, carbon black and iron phosphide; iii) 10 to 40% by weight of water and iv) if desired, a total of up to 30% by weight of other active or auxiliary substances, the quantities adding up to 100% by weight; to the metal surface provided with a chemical conversion layer a) and curing the coating composition thus applied at a peak metal temperature of 130 to 159Â° C., and said composition (B) comprising i) 5 to 40% by weight of an organic binder containing aa) at least one epoxy resin; ab) at least one hardener selected from cyanoguanidine, benzoguanamine and plasticized urea resin; ac) at least one amine adduct selected from polyoxyalkylene triamine and epoxy resin/amine adducts ii) 0 to 15% by weight of an anti-corrosion pigment; iii) 40 to 70% by weight of at least one electrically conductive substance in powder form, selected from zinc, aluminium, graphite, molybdenum sulfide, carbon black and iron phosphide; iv) 0 to 45% by weight of a solvent and, if desired, up to 50% by weight of other active or auxiliary substances; the percentages of the components adding up to 100% by weight, to the metal surface provided with a chemical conversion layer a) and curing the coating composition thus applied at a peak metal temperature (PMT) of 160 to 260Â° C.