Electroconductive composite substrates coated with electrodepositable coating compositions and methods of preparing them

Abstract

A process for coating a plastic, electroconductive substrate is provided, comprising: (a) electrophoretically depositing on the substrate a curable, electrodepositable coating composition to form an electrodeposited coating over at least a portion of the substrate, the electrodepositable coating composition comprising a resinous phase dispersed in an aqueous medium, said resinous phase comprising: (1) a resin component containing an active hydrogen-containing, cationic or anionic resin comprising an acrylic, polyester, polyurethane and/or polyepoxide polymer; and (2) a curing agent; and (b) heating the coated substrate to a temperature less than 250° F. for a time sufficient to cure the electrodeposited coating on the substrate.

What is claimed is: 
     
         1 . A process for coating a plastic, electroconductive substrate comprising:
 (a) electrophoretically depositing on the substrate a curable, electrodepositable coating composition to form an electrodeposited coating over at least a portion of the substrate, the electrodepositable coating composition comprising a resinous phase dispersed in an aqueous medium, said resinous phase comprising:
 (1) a resin component containing an active hydrogen-containing, cationic or anionic resin comprising an acrylic, polyester, polyurethane and/or polyepoxide polymer; and 
 (2) a curing agent; and 
   (b) heating the coated substrate to a temperature less than 250° F. for a time sufficient to cure the electrodeposited coating on the substrate.   
     
     
         2 . The process of  claim 1 , wherein in step (b), the coated substrate is heated to a temperature less than 225° F. 
     
     
         3 . The process of  claim 1 , wherein the substrate comprises a resinous matrix reinforced with fibers. 
     
     
         4 . The process of  claim 3 , wherein the resinous matrix comprises polyethylene, polypropylene, thermoplastic urethane, polycarbonate, thermosetting sheet molding compound, reaction-injection molding compound, acrylonitrile-based materials, nylon, polypropylene, polybutylene terephthalate, polystyrene, polyaniline, polypyrrole, polyepoxide, poly(methyl methacrylate), polyurethane, and/or polycarbonate. 
     
     
         5 . The process of  claim 3 , wherein the fibers are electroconductive. 
     
     
         6 . The process of  claim 1 , wherein the electroconductive composite substrate further comprises electroconductive particulate filler distributed throughout the resinous matrix and comprising one or more of zinc, ferrophosphorus, tungsten, carbon, nickel, aluminum, copper, iron, steel, molybdenum disulphide, iron oxide, antimony doped titanium dioxide, nickel-doped titanium dioxide, graphite, silver, and/or aluminum particles. 
     
     
         7 . The process of  claim 1 , wherein a primer or adhesion promoter coating layer is deposited on the surface of the substrate prior to application of the curable, electrodepositable coating composition. 
     
     
         8 . The process of  claim 7 , wherein an adhesion promoter coating layer is deposited on the surface of the substrate from a composition comprising:
 (a) a halogenated polyolefin;   (b) a film-forming polymer different from the polyolefin (a); and   (c) an electroconductive pigment.