Coating compositions exhibiting corrosion resistance properties, related coated articles and methods

Abstract

Disclosed are coating compositions, such as primer compositions, suitable for providing corrosion protection to metal substrates, as well as related coated articles and methods.

1 . A metal article at least partially coated with a multi-component composite coating comprising: 
 (a) a zinc-rich primer coating; and    (b) an electrodeposited coating deposited over at least a portion of the zinc-rich primer coating,    wherein the article is resistant to corrosion after 500 hours of exposure when the total combined dry film thickness of the zinc-rich primer and the electrodeposited coating is 1.5 mils or less.    
   
   
       2 . The article of  claim 1 , wherein the zinc-rich primer coating is deposited from a composition comprising zinc powder.  
   
   
       3 . The article of  claim 2 , wherein the zinc powder is present in an amount of at least 25 percent by weight, based on the total weight of the zinc particles.  
   
   
       4 . The article of  claim 1 , wherein the zinc-rich primer coating is deposited from a composition comprising zinc/tin alloy particles.  
   
   
       5 . The article of  claim 1;  wherein the zinc-rich primer coating is deposited from a composition comprising a binder formed from titanate and/or a partial hydrolysate thereof.  
   
   
       6 . The article of  claim 5 , wherein the binder comprises a hybrid organic-inorganic copolymer formed from: 
 (1) a titanate and/or a partial hydrolysate thereof; and    (2) a polyfunctional polymer having functional groups reactive with alkoxy groups of the titanate and/or the partial hydrolysate thereof.    
   
   
       7 . The article of  claim 6 , wherein the polyfunctional polymer comprises a polyol.  
   
   
       8 . The article of  claim 6 , wherein the polyfunctional polymer is an acrylic polymer, a polyester polymer, a polyurethane polymer, a polyether polymer, a silicon-based polymer, or mixture thereof.  
   
   
       9 . The article of  claim 7 , wherein the polyol is formed from reactants comprising (i) a polyol comprising an aromatic group and (ii) an alkylene oxide.  
   
   
       10 . The article of  claim 5 , wherein the titanate comprises a chelated titanate.  
   
   
       11 . The article of  claim 5 , wherein the binder is present in the composition in an amount of 2 to 10 percent by weight, based on the total weight of solids in the composition.  
   
   
       12 . The article of  claim 1 , wherein the article is a small part.  
   
   
       13 . The article of  claim 1 , wherein the total combined dry film thickness of the zinc-rich primer and the electrodeposited coating is 1 mil or less.  
   
   
       14 . The article of  claim 1 , wherein the electrodeposited coating is deposited directly over at least a portion of the zinc-rich primer.  
   
   
       15 . The article of  claim 1 , wherein the article is resistant to corrosion after 1000 hours of exposure when the total combined dry film thickness of the zinc-rich primer and the electrodeposited coating is 1.5 mils or less.  
   
   
       16 . A chrome-free coating composition comprising: 
 (a) metal particles; and    (b) a film-forming binder comprising a hybrid organic-inorganic copolymer formed from: 
 (i) a titanate and/or a partial hydrolysate thereof, and  
 (ii) a polyfunctional polymer having functional groups reactive with alkoxy groups of the titanate and/or the partial hydrolysate thereof.  
   
   
   
       17 . The composition of  claim 16 , wherein the composition comprises zinc powder.  
   
   
       18 . The composition of  claim 16 , wherein the zinc powder is present in the composition in an amount of at least 50 percent by weight, based on the total weight of the composition.  
   
   
       19 . The composition of  claim 16 , wherein the polyfunctional polymer is a polyol.  
   
   
       20 . A coating composition comprising: 
 (a) metal particles; and    (b) a film-forming binder comprising a structure represented by the general formula:                          wherein P is the residue of a polyfunctional polymer, and each n is an integer having a value of 1 or more and may be the same or different.