Hureaulite conversion coating as a base for the bonding of rubber to metal

Abstract

A metal-mineral system and method for making and using it. The metal-mineral system creates a bond between a metallic substrate and a top layer, preferably of rubber (to be adhered to). The metal-mineral system includes a fine crystalline coating of hureaulite (manganous iron phosphate) that is formed at less than 80° C. as a conversion coating onto the metallic substrate. The conversion coating passivates the metallic substrate and provides an enhanced surface area of contact that anchors the adhesive to the conversion coating. An adhesive is bonded to the conversion coating. A rubber top layer is applied to the adhesive. The metal-mineral system is resistant to breakage under stress and chemical attack. The method for making the metal-mineral system creates a reduced quantity of sludge with a beneficial effect on waste treatment procedures.

What is claimed is:  
     
         1 . A metal-mineral system for creating a bond between a metallic substrate and an adherent top layer, the metal-mineral system comprising: 
 a fine crystalline conversion coating of manganous iron phosphate formed at less than 80° C. onto the metallic substrate, the conversion coating serving to passivate the metallic substrate and provide an enhanced surface area of contact for anchoring an adhesive to the conversion coating;    an adhesive bonded to the conversion coating; and    a rubber top layer applied to the adhesive, the metal-mineral system being resistant to breakage under stress and chemical attack.    
     
     
         2 . The metal-mineral system of  claim 1 , wherein the manganous iron phosphate coating comprises: 
 an average crystal size of about 5 to about 25 microns.    
     
     
         3 . The metal-mineral system of  claim 2 , wherein the manganous iron phosphate coating comprises: 
 an average crystal size of about 10 to about 20 microns.    
     
     
         4 . The metal-mineral system of  claim 1  wherein the rubber is selected from the group consisting of natural and synthetic high polymers.  
     
     
         5 . The metal-mineral system of  claim 1 , wherein the metallic substrate comprises steel.  
     
     
         6 . The metal-mineral system of  claim 1 , wherein the metallic substrate comprises zinc.  
     
     
         7 . The metal-mineral system of  claim 1 , wherein the metallic substrate comprises a ferrous metal  
     
     
         8 . The metal-mineral system of  claim 1 , wherein the metallic substrate comprises a galvanized steel.  
     
     
         9 . The metal-mineral system of  claim 1 , wherein the fine crystalline conversion coating is formed at a temperature between 50° C.-80° C.  
     
     
         10 . The metal-mineral system of  claim 1 , wherein the fine crystalline conversion coating is formed at a temperature between 50° C.-60° C.  
     
     
         11 . The metal-mineral system of  claim 1 , wherein the conversion coating of manganous iron phosphate comprises iron hureaulite.  
     
     
         12 . A method of making a metal-mineral system for creating a bond between a metallic substrate and an adherent top layer, comprising the steps of: 
 preparing an oil-free, clean metal surface;    exposing the oil-free, clean metal surface to a nucleating solution to form a modified metal surface;    immersing the modified metal surface in a manganese-iron phosphating bath at less than 80° C. to form a fine crystalline conversion coating of manganese iron phosphate upon the modified metal surface;    bonding an adhesive to the conversion coating; and    applying a rubber top layer to the adhesive, the metal-mineral system have the characteristics of resistance to breakage under stress and chemical attack.    
     
     
         13 . The method of  claim 12  wherein the temperature of the manganese-iron phosphating bath is at an average temperature between 50° C.-80° C.  
     
     
         14 . The method of  claim 12  wherein the temperature of the manganese-iron phosphating bath is at an average temperature between 50° C. -60° C.  
     
     
         15 . The method of  claim 12  wherein the step of bonding the adhesive includes bonding the adhesive relatively uniformly over the entire metallic substrate.  
     
     
         16 . The method of  claim 12 , wherein the processing solution operates at a Q-value of about 3.5, with a free acid amount between 2 and 6 points, and a total acid amount between 35 and 60 points.  
     
     
         17 . A method of using the metal-mineral system of  claim 1  comprising the steps of: 
 providing a metal-mineral system according to the method of  claim 12;  and  
 deploying the system in a rubber bonding environment where the system has characteristics of resistance to breakage, stress and chemical attack, while generating relatively low amounts of sludge during its preparation.