Methods for inhibiting corrosion in brazed metal surfaces and coolants and additives for use therein

Abstract

Disclosed are coolants comprising brazed metal corrosion inhibitors. In one embodiment, the disclosed brazed metal corrosion inhibitor will comprise a polycarboxylic acid functional compound having the structure: wherein R 1 , R 2 , R 3 , and R 4 are each independently selected from the group consisting of H, OH, COOH, C 1 -C 10 alkyl groups, glycol esters, anhydride groups, —COOM, and combinations thereof, wherein M is at least one of H, alkali metal ions, alkali earth metal ions, NH4 + , amines, imidazoline, polyalcohol esters, C1 to C12 alkyl groups, and combinations thereof; wherein (1) at least three of R 1 , R 2 , R 3 , and R 4 contain the group —COOM, wherein M is defined above; or (2) at least two of R 1 , R 2 , R 3 , and R 4 contain an anhydride group, and at least one of R 1 , R 2 , R 3 , and R 4 contain the group —COOM, wherein M is defined above.

1 . A method for inhibiting corrosion in a brazed metal surface in communication with a coolant comprising:
 contacting said brazed metal surface with a coolant comprising a brazed metal corrosion inhibitor comprising a polycarboxylic acid functional compound comprising, on average per molecule, at least three groups selected from the group consisting of anhydride groups, —COOM, and combinations thereof, wherein M is at least one of H, alkali metal ions alkali earth metal ions, NH4+ amines, imidazoline, polyalcohol esters, C1 to C12 alkyl groups, and combinations thereof.   
   
   
       2 . The method of  claim 1 , wherein the polycarboxylic acid functional compound comprises a tall oil fatty acid derived from a cyclohexenoic acid containing compound. 
   
   
       3 . The method of  claim 2 , wherein the cyclohexenoic containing compound comprises a maleated tall oil fatty acid, a maleated tall oil fatty acid salt, a reaction product derived from a maleated tall oil fatty acid, a reaction product derived from a maleated tall oil fatty acid salt, a reaction product derived from a ethylene glycol ester, a reaction product derived from a ethylene glycol ester salt, or a maleated tall oil. 
   
   
       4 . The method of  claim 1 , wherein the polycarboxylic acid functional compound comprises a maleinized unsaturated fatty acid, a cyrlate copolymer, a styrene copolymer, or a polymerizable acid graft polymer. 
   
   
       5 . The method of  claim 1 , wherein the polycarboxylic acid functional compound has the structure: 
     
       
         
         
             
             
         
       
       wherein R 1 , R 2 , R 3 , and R 4  are each independently selected from the group consisting of H, OH, COOH, C 1 -C 10  alkyl groups, glycol esters, anhydride groups, —COOM, and combinations thereof, wherein M is at least one of H, alkali metal ions, alkali earth metal ions, NH4 + , amines, imidazoline, polyalcohol esters, C1 to C12 alkyl groups, and combinations thereof; 
       with the proviso that:
 (1) at least three of R 1 , R 2 , R 3 , and R 4  contain the group —COOM, wherein M is defined above or 
 (2) at least two of R 1 , R 2 , R 3 , and R 4  contain an anhydride group, and at least one of R 1 , R 2 , R 3 , and R 4  contain the group —COOM, wherein M is defined above. 
 
     
   
   
       6 . The method of  claim 5 , wherein R 3  is H or COOH. 
   
   
       7 . The method of  claim 6 , wherein R 1  is a group having a structure (CH) x —(COO)—[(CH2) y —O] z —H wherein: x is 0 to 10, y is from 1 to 5 and z is from 0 to 5. 
   
   
       8 . The method of  claim 5 , wherein R 4  is a C 1 -C 10  alkyl group. 
   
   
       9 . The method of  claim 5 , wherein R 2  is COOH. 
   
   
       10 . The method of  claim 5 , wherein R 2 , and R 3  comprise an anhydride group. 
   
   
       11 . The method of  claim 1  wherein the brazed aluminum surface comprises residual flux agent. 
   
   
       12 . The method of  claim 11  wherein the residual flux agent comprises halogen atoms. 
   
   
       13 . The method of  claim 12  wherein the halogen atoms are fluorine atoms. 
   
   
       14 . The method of  claim 11  wherein the residual flux agent comprises an alkaline metal halogen compound or an alkaline earth metal halogen compound. 
   
   
       15 . The method of  claim 14  wherein the residual flux agent comprises a mixture of K 3 AlF 6 , K 2 AlF 5  and KAlF 4 . 
   
   
       16 . A cooling system resistant to corrosion, said cooling system comprising:
 at least one cooling system component comprising a brazed metal surface, and   a coolant in communication with the brazed metal surface, said coolant comprising an acid functional corrosion inhibiting component comprising a brazed metal corrosion inhibitor, wherein the brazed metal corrosion inhibitor comprises a polycarboxylic acid functional compound comprising, on average per molecule, at least three groups selected from the group consisting of anhydride groups, —COOM, and combinations thereof, wherein M is at least one of H, alkali metal ions, alkali earth metal ions, NH4+, amines, imidazoline, polyalcohol esters, C1 to C12 alkyl groups, and combinations thereof.   
   
   
       17 . The system of  16 , wherein the brazed aluminum surface comprises a fluxing agent. 
   
   
       18 . The system of  17 , wherein the brazed aluminum surface comprises an alkaline metal chloride, an alkali earth metal chloride, alkaline metal fluoride, or an alkaline earth metal chloride. 
   
   
       19 . The system of  18 , wherein the fluxing agent comprises alkaline metal fluoride, wherein the alkaline metal fluoride is selected from K 3 AlF 6 , K 2 AlF 5 , and KAlF 4 . 
   
   
       20 . The system of  claim 16 , wherein the polycarboxylic acid functional compound comprises a tall oil fatty acid derived from a cyclohexenoic acid containing compound. 
   
   
       21 . The system of  claim 20 , wherein the cyclohexenoic containing compound comprises a maleated tall oil fatty acid, a maleated tall oil fatty acid salt, a reaction product derived from a maleated tall oil fatty acid, a reaction product derived from a maleated tall oil fatty acid salt, a reaction product derived from a ethylene glycol ester, a reaction product derived from a ethylene glycol ester salt, or a maleated tall oil. 
   
   
       22 . The system of  claim 16 , wherein the polycarboxylic acid functional compound comprises a maleinized unsaturated fatty acid, a cyrlate copolymer, a styrene copolymer, or a polymerizable acid graft polymer. 
   
   
       23 . The system of  claim 16 , wherein the polycarboxylic acid functional compound has the structure: 
     
       
         
         
             
             
         
       
       wherein R 1 , R 2 , R 3 , and R 4  are each independently selected from the group consisting of H, OH, COOH, C 1 -C 10  alkyl groups, glycol esters, anhydride groups, —COOM, and combinations thereof, wherein M is at least one of H, alkali metal ions, alkali earth metal ions, NH4 + , amines, imidazoline, polyalcohol esters, C1 to C12 alkyl groups, and combinations thereof; 
       with the proviso that:
 (1) at least three of R 1 , R 2 , R 3 , and R 4  contain the group —COOM, wherein M is defined above or 
 (2) at least two of R 1 , R 2 , R 3 , and R 4  contain an anhydride group, and at least one of R 1 , R 2 , R 3 , and R 4  contain the group —COOM, wherein M is defined above. 
 
     
   
   
       24 . The system of  claim 23 , wherein R 3  is H or COOH. 
   
   
       25 . The system of  claim 23 , wherein R 1  is a group having a structure (CH) x —(COO)—[(CH2) y —O] z —H wherein: x is 0 to 10, y is from 1 to 5 and z is from 0 to 5. 
   
   
       26 . The system of  claim 23 , wherein R 4  is a C 1 -C 10  alkyl group. 
   
   
       27 . The system of  claim 23 , wherein R 2  is COOH. 
   
   
       28 . The system of  claim 23 , wherein R 2 , and R 3  comprise an anhydride group. 
   
   
       29 . The system of  claim 16 , further comprising an ion exchange resin in contact with the coolant. 
   
   
       30 . A cooling system resistant to corrosion, said cooling system comprising:
 a first cooling subsystem comprising at least one cooling system component comprising a brazed metal surface,   a first coolant in communication with the brazed metal surface, said first coolant comprising an acid functional corrosion inhibiting component comprising a brazed metal corrosion inhibitor wherein the brazed metal corrosion inhibitor comprises a polycarboxylic acid functional compound comprising, on average per molecule, at least three groups selected from the group consisting of anhydride groups, —COOM, and combinations thereof, wherein M is at least one of H, alkali metal ions, alkali earth metal ions, NH4+, amines, imidazoline, polyalcohol esters, C1 to C12 alkyl groups, and combinations thereof,   a second cooling subsystem, and   a second coolant in communication with the second cooling system, wherein the second coolant does not contact the first cooling subsystem, and wherein the second coolant does not contact a brazed aluminum surface.   
   
   
       31 . The cooling system of  claim 30 , further comprising a heat exchanger configured to transfer heat between the first cooling subsystem and the second cooling subsystem. 
   
   
       32 . The cooling system of  claim 30 , wherein the second cooling subsystem is configured to cool a fuel cell.