Corrosion inhibitor for protecting metallic materials in strongly alkaline medium

Abstract

Corrosion inhibitor and method of protecting metallic materials in strongly alkaline medium by means of a corrosion inhibitor, characterized in that it contains an amine containing at least one CH group bound to the nitrogen.

1 . Corrosion inhibitor, comprising an amine containing at least one CH group bound to the nitrogen. 
     
     
         2 . Corrosion inhibitor according to  claim 1 , wherein the amine has the formula (I) below 
       
         
           
           
               
               
           
         
         where 
         R 1  is a C 1 -C 6 -alkyl radical, H or a benzyl radical and 
         R 2  is a C 1 -C 6 -alkyl radical, H or a benzyl radical, 
         where the benzyl radicals optionally bear further substituents, selected from the group consisting of C 1 -C 6 -alkyl and a halogen. 
       
     
     
         3 . Corrosion inhibitor according to  claim 1 , wherein the amine is a polyamine selected from the group consisting of the reaction products of dichloroethane with ammonia and/or amines and from the group consisting of the reaction products of ethylene oxide with ammonia or amines. 
     
     
         4 . Corrosion inhibitor according to  claim 3 , wherein the polyamine has one of the formulae (II) and (III) below:
   H p —N(CH 2 —CH 2 ) q —[NH r —(CH 2 —CH 2 ) s ] n — NH     t     (II),     NH 2 —CH 2 —CH 2 —CH 2 —[NH r —(CH 2 —CH 2 —CH 2)     s   ] n —NH 2   (III),   where   n is 0 or an integer from 1 to 300,   p, q, s and t are each 1 or 2, and   r is 0 or 1,   where the sum of the substituents on a nitrogen is three or   an anion is additionally present to balance the charge when a nitrogen is bound to 4 substituents.   
     
     
         5 . Corrosion inhibitor according to  claim 3 , wherein the polyamine has the formula (IV) below: 
       
         
           
           
               
               
           
         
         where y is H or an aminoalkyl radical. 
       
     
     
         6 . Corrosion inhibitor according to  claim 3 , wherein the polyamine has one of the formulae (V) and (VI) below:
   NH 2 —CH 2 —CH 2 —[NH—CH 2 —CH 2 ] n —NH 2   (V),     NH 2 —CH 2 —CH 2 —CH 2 —[NH—CH 2 —CH 2 —CH 2 ] n —NH 2   (VI),   where n is 0 or an integer from 1 to 300.   
     
     
         7 . Method of protecting metallic materials in strongly alkaline medium by means of a corrosion inhibitor, comprising providing a corrosion inhibitor comprising an polyamine having a CH group bound to the nitrogen, wherein the polyamine selected from the group consisting of the reaction products of dichloroethane with ammonia and/or amines and from the group consisting of the reaction products of ethylene oxide with ammonia or amines. 
     
     
         8 . Method according to  claim 7 , wherein the polyamine has one of the formulae (II) and (III) below:
   H p —N(CH 2 —CH 2 ) q —[NH r —(CH 2 —CH 2 ) s ] n — NH     t     (II),     NH 2 —CH 2 —CH 2 —CH 2 —[NH r —(CH 2 —CH 2 —CH 2)     s   ] n —NH 2   (III),   where   n is 0 or an integer from 1 to 300,   p, q, s and t are each 1 or 2, and   r is 0 or 1,   where the sum of the substituents on a nitrogen is three or   an anion, additionally present to balance the charge when a nitrogen is bound to 4 substituents.   
     
     
         9 . Method according to  claim 7 , wherein the polyamine has the formula (IV) below: 
       
         
           
           
               
               
           
         
         where y is H or an aminoalkyl radical. 
       
     
     
         10 . Method according to  claim 7 , wherein the polyamine is selected from the group consisting of ethylenediamine, diethylenetriamine, aminoethylpiperazine, piperazine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and hexaethyleneheptamine. 
     
     
         11 . Method according to  claim 7 , wherein the polyamine is pentaethylenehexamine. 
     
     
         12 . Method according to  claim 7  wherein from 0.001 to 200 000 ppm of polyamine is/are added to the medium. 
     
     
         13 . Method according to  claim 7 , wherein the corrosion inhibitor is added to an alkaline medium.