Polymer-coated metal composites by dip autopolymerization

Abstract

A composition and method is described for providing conformal protective or decorative polymer coatings on metals such as aluminum, copper, iron, steel, zinc, and their by dip autopolymerization. In accordance with the present invention, an acidic solution of organic monomer undergoes autopolymerization upon contact with a metal substrate, thereby forming a polymeric coating on the substrate. The method comprises providing the acidic monomer solution, dipping the metal substrate to be coated for a prescribed period of time depending on the thickness of the coating desired, and then removing the substrate from the solution. Importantly, the polymerization requires no application of external driving force, such as thermal or electrical energy. The coatings thus formed are up to 50 microns thick, and conform to the shape of the substrate. These coatings further have uniform thickness, and excellent thermal stability and protective properties. In one preferred embodiment of the present invention, the composition comprises an acidic solution of an organic electron acceptor monomer that undergoes autopolymerization in contact with a metal substrate, thereby forming a polymeric coating on the substrate. In another preferred embodiment of the present invention, the composition comprises an acidic solution of an organic electron acceptor monomer and an organic electron donor monomer that undergo autopolymerization in contact with a metal substrate, thereby forming a polymeric coating on the substrate. Metal-polymer composites are also described.

What is claimed is:  
     
         1 . A polymer-coated metal composite consisting of a metal substrate and a single layer of polymeric coating produced by: 
 providing an acidic starting solution consisting essentially of 
 at least one electron acceptor monomer selected from the group consisting of acrylamides, alkyl, cycloalkyl, aryl, and aralkyl acrylates, methacrylamide, alkyl, cycloalkyl, aryl, and aralkyl methacrylates, acrolein, methacrolein, thiocarboxylic acids, thiocarboxamides, alkyl, cycloalkyl, aryl, and aralkyl thiocarboxylates, dithioacrylic acids, dithiomethacrylic acids, and alkyl, cycloalkyl, aryl, and aralkyl esters of dithiocarboxylic acids;  
 at least one electron donor monomer selected from the group consisting of 1-alkenes, alkyl, cycloalkyl, or aralkyl-substituted 1-alkenes, internal olefins, alkyl, cycloalkyl, aryl, or aralkyl-substituted internal olefins, conjugated dienes, and alkyl, cycloalkyl, aryl, and aralkyl-substituted conjugated dienes; and  
 at least one solvent which dissolves or forms an emulsion of the monomers, wherein the at least one electron acceptor monomer and the at least one electron donor monomer are polymerizable at the metal substrate upon contact with the metal substrate in the absence of other catalyst or catalysts;  
 dipping the metal substrate into the starting solution, wherein the metal substrate is a metal which will initiate polymerization of the at least two monomers on the surface of the metal substrate in the absence of other catalyst or catalysts; and  
 leaving the metal substrate in the starting solution for a time effective to form a polymeric coating by polymerization which occurs at the metal substrate and upon contact with the metal substrate in the absence of other catalyst or catalysts.  
   
     
     
         2 . The polymer-coated composite of  claim 1 , wherein the pH of the starting solution is less than 6.5.  
     
     
         3 . The polymer-coated composite of  claim 1 , wherein the metal substrate is a metal selected from the group consisting of 
 aluminum, copper, iron, steel, zinc, transition metals, chromium, tin, indium, nickel, cobalt, titanium, and alloys thereof.    
     
     
         4 . The polymer-coated composite of  claim 3 , wherein the metal substrate is aluminum, copper, iron, zinc, or steel.  
     
     
         5 . The polymer-coated composite of  claim 1 , wherein the electron acceptor monomer is 4-carboxyphenyl maleimide, N-phenyl maleimide, bis maleimide, or 2-(methacryloyloxy)ethyl acetoacetate.  
     
     
         6 . A polymer-coated metal composite produced by: 
 providing an acidic starting solution consisting essentially of 
 at least one electron acceptor monomer selected from the group consisting of acrylamides, alkyl, cycloalkyl, aryl, and aralkyl acrylates, methacrylamide, alkyl, cycloalkyl, aryl, and aralkyl methacrylates, acrolein, methacrolein, thiocarboxamides, alkyl, cycloalkyl, aryl, and aralkyl thiocarboxylates, and alkyl, cycloalkyl, aryl, and aralkyl esters of dithiocarboxylic acids;  
 at least one electron donor monomer selected from the group consisting of 1-alkenes, alkyl, cycloalkyl, or aralkyl-substituted 1-alkenes, internal olefins, alkyl, cycloalkyl, aryl, or aralkyl-substituted internal olefins, conjugated dienes, and alkyl, cycloalkyl, aryl, and aralkyl-substituted conjugated dienes; and  
 at least one solvent which dissolves or forms an emulsion of the monomers, wherein the at least one electron acceptor monomer and the at least one electron donor monomer are polymerizable at a metal substrate upon contact with the metal substrate in the absence of other catalyst or catalysts;  
 dipping the metal substrate into the starting solution, wherein the metal substrate is a metal which will initiate polymerization of the at least two monomers on the surface of the metal substrate in the absence of other catalyst or catalysts; and  
 leaving the metal substrate in the starting solution for a time effective to form a polymeric coating by polymerization which occurs at the metal substrate and upon contact with the metal substrate in the absence of other catalyst or catalysts.  
   
     
     
         7 . The polymer-coated composite of  claim 6 , wherein 
 the pH of the starting solution is less than 6.5.    
     
     
         8 . The polymer-coated composite of  claim 6 , wherein the metal substrate is a metal selected from the group consisting of 
 aluminum, copper, iron, steel, zinc, transition metals, chromium, tin, indium, nickel, cobalt, titanium, and alloys thereof.    
     
     
         9 . The polymer-coated composite of  claim 8 , wherein 
 the metal substrate is aluminum, copper, iron, zinc, or steel.    
     
     
         10 . A polymer-coated metal composite produced by: 
 providing an acidic starting solution consisting essentially of 
 at least one electron acceptor monomer selected from the group consisting of acrylic acids, acrylamides, alkyl, cycloalkyl, aryl, and aralkyl acrylates, methacrylic acid, methacrylamide, alkyl, cycloalkyl, aryl, and aralkyl methacrylates, acrolein, methacrolein, thiocarboxylic acids, thiocarboxamides, alkyl, cycloalkyl, aryl, and aralkyl thiocarboxylates, dithioacrylic acids, dithiomethacrylic acids, and alkyl, cycloalkyl, aryl, and aralkyl esters of dithiocarboxylic acids;  
 at least one electron donor monomer selected from the group consisting of, alkyl, cycloalkyl, or aralkyl-substituted 1-alkenes, internal olefins, alkyl, cycloalkyl, aryl, or aralkyl-substituted internal olefins, conjugated dienes, and alkyl, cycloalkyl, aryl, and aralkyl-substituted conjugated dienes; and  
 at least one solvent which dissolves or forms an emulsion of the monomers, wherein the at least one electron acceptor monomer and the at least one electron donor monomer are polymerizable at a metal substrate upon contact with the metal substrate in the absence of other catalyst or catalysts;  
 dipping the metal substrate into the starting solution, wherein the metal substrate is a metal which will initiate polymerization of the at least two monomers on the surface of the metal substrate in the absence of other catalyst or catalysts; and  
 leaving the metal substrate in the starting solution for a time effective to form a polymeric coating by polymerization which occurs at the metal substrate and upon contact with the metal substrate in the absence of other catalyst or catalysts.  
   
     
     
         11 . The polymer-coated composite of  claim 10 , wherein 
 the pH of the starting solution is less than 6.5.    
     
     
         12 . The polymer-coated composite of  claim 12 , wherein the metal substrate is a metal selected from the group consisting of 
 aluminum, copper, iron, steel, zinc, transition metals, chromium, tin, indium, nickel, cobalt, titanium, and alloys thereof. cm  13 . The polymer-coated composite of  claim 12 , wherein    the metal substrate is aluminum, copper, iron, zinc, or steel.