Quaternary ammonium salts as a conversion coating or coating enhancement

Abstract

Disclosed are quaternary ammonium salts containing non-halogen anions such as carbonates, bicarbonates, phosphates, glycolates and mixtures thereof as conversion coatings or additives imparting anti-corrosive properties to paints. The invention relates to a method for inhibiting the corrosion of metal surfaces by applying a composition containing one or more quaternary ammonium carbonate or bicarbonate. The disclosure is also directed to anti-corrosive coatings for metal substrates containing these compounds and to metal substrates having these anticorrosive coatings.

1 . A method for applying a conversion coating to the surface of a metal substrate, said method comprising the step of contacting the substrate with a composition comprising 
 (a) at least one quaternary ammonium salt containing a non-halogen anion, and    (b) optionally, a solvent.    
   
   
       2 . The method of  claim 1 , wherein the quaternary ammonium salt has the formula  
     
       
         
         
             
             
         
       
     
     wherein R 1  is an optionally aryl-substituted C 1-20  alkyl group, and R 2  is an optionally aryl-substituted C 1-20  alkyl group, R 3  and R 4  independently of each other are C 1-4  alkyl groups, X n−  is an anion selected from the group consisting of hydroxide, carbonate, bicarbonate, phosphates, phosphites, hypophosphite, nitrate, sulfates, borates, anions of saturated and unsaturated acyclic C 1-20  monocarboxylic acids, anions of saturated and unsaturated acyclic C 2-20  dicarboxylic acids and anions of hydroxy-substituted carboxylic acids, and n denotes the appropriate number of negative charges of said anion.  
   
   
       3 . The method of  claim 2 , wherein X n−  is selected from the group consisting of carbonate, bicarbonate, phosphates and glycolate.  
   
   
       4 . The method of  claim 2 , wherein R 3  and R 4  are methyl groups.  
   
   
       5 . The method of  claim 2 , wherein R 1  is methyl.  
   
   
       6 . The method of  claim 2 , wherein R 2  is benzyl or phenylethyl.  
   
   
       7 . The method of  claim 2 , wherein R 1  and R 2  are the same C 1-20  alkyl groups  
   
   
       8 . The method of  claim 7 , wherein R 1  and R 2  are C 10  alkyl groups.  
   
   
       9 . The method of  claim 8 , wherein R 1  and R 2  are n-C 10  alkyl groups.  
   
   
       10 . The method of  claim 9 , wherein the quaternary ammonium salt is di-n-decyldimethylammonium carbonate and/or di-n-decyldimethylammonium bicarbonate.  
   
   
       11 . The method of  claim 1 , wherein the metal substrate is steel.  
   
   
       12 . The method of  claim 11 , wherein the steel is coiled sheet steel.  
   
   
       13 . An article of manufacture comprising a metal substrate treated according to the method of  claim 1 .  
   
   
       14 . The article of manufacture of  claim 13  wherein the metal substrate is steel.  
   
   
       15 . An anticorrosive paint comprising 
 (a) at least one quaternary ammonium salt containing a non-halogen anion,    (b) a binder,    (c) optionally, a solvent and    (d) optionally, a pigment.    
   
   
       16 . The anticorrosive paint of  claim 15 , wherein the quaternary ammonium salt has the formula  
     
       
         
         
             
             
         
       
     
     wherein R 1  is an optionally aryl-substituted C 1-20  alkyl group, and R 2  is an optionally aryl-substituted C 1-20  alkyl group, R 3  and R 4  independently of each other are C 1-4  alkyl groups, X n−  is an anion selected from the group consisting of hydroxide, carbonate, bicarbonate, phosphates, phosphites, hypophosphite, nitrate, sulfates, borates, anions of saturated and unsaturated acyclic C 1-20  monocarboxylic acids, anions of saturated and unsaturated acyclic C 2-20  dicarboxylic acids and anions of hydroxy-substituted carboxylic acids, and n denotes the appropriate number of negative charges of said anion.  
   
   
       17 . The anticorrosive paint of  claim 15 , wherein the binder is selected from the group consisting of acrylic resins, casein (milk protein), vinyl resins, latex resins, acetate resins, epoxy resins and mixtures thereof.  
   
   
       18 . The anticorrosive paint of  claim 15 , which is a latex paint.  
   
   
       19 . The anticorrosive paint of  claim 15 , which is an enamel spray paint.  
   
   
       20 . The anticorrosive paint of  claim 15 , which is an e-coating paint.  
   
   
       21 . The anticorrosive paint of  claim 15 , which is an acrylic paint.  
   
   
       22 . An article of manufacture comprising a metal substrate painted with the anticorrosive paint of  claim 15 .  
   
   
       23 . A method of preparing an anticorrosive paint or coating comprising adding to the paint or coating a quaternary ammonium salt having the formula  
     
       
         
         
             
             
         
       
     
     wherein R 1  is an optionally aryl-substituted C 1-20  alkyl group, and R 2  is an optionally aryl-substituted C 1-20  alkyl group, R 3  and R 4  independently of each other are C 1-4  alkyl groups, X n−  is an anion selected from the group consisting of hydroxide, carbonate, bicarbonate, phosphates, phosphites, hypophosphite, nitrate, sulfates, borates, anions of saturated and unsaturated acyclic C 1-20  monocarboxylic acids, anions of saturated and unsaturated acyclic C 2-20  dicarboxylic acids and anions of hydroxy-substituted carboxylic acids, and n denotes the appropriate number of negative charges of said anion.