Method for making a blocked amine

Abstract

A single component epoxy coating precursor and a method for making such a precursor, a low VOC epoxy coating and a method for making such a coating, and a method for making a blocked amine which is more stable than previously known ones. The single component epoxy coating precursor includes an epoxy resin, a first solvent, and a blocked amine. The single component epoxy coating precursor has a viscosity after 30 days at a temperature of 55° C. of less than 16 stokes.

What is claimed is:  
     
         1 . A method for making a blocked amine comprising: 
 mixing a solvent capable of forming an azeotrope with water, an amine, and an amine blocker selected from ketones and aldehydes in a reaction vessel to form a reaction mixture;    removing ambient moisture from the reaction vessel;    reacting the amine and the amine blocker to form the blocked amine and water of reaction;    removing the water of reaction from the reaction mixture while the amine and the amine blocker are reacted; and    recovering the blocked amine while maintaining the absence of moisture.    
     
     
         2 . The method of  claim 1  wherein the water of reaction is removed for a length of time until 100% of a theoretical water of reaction is removed from the reaction mixture.  
     
     
         3 . The method of  claim 1  wherein the water of reaction is removed for a length of time until the water of reaction ceases to azeotrope.  
     
     
         4 . The method of  claim 1  further comprising heating the reaction mixture until the water of reaction is removed.  
     
     
         5 . The method of  claim 4  further comprising cooling the reaction mixture after the water of reaction has been removed.  
     
     
         6 . The method of  claim 5  further comprising heating the reaction mixture and placing the reaction mixture under a vacuum after the water of reaction has been removed.  
     
     
         7 . The method of  claim 1  wherein the solvent capable of forming an azeotrope with water is capable of forming a binary or ternary azeotrope with water.  
     
     
         8 . The method of  claim 1  wherein the solvent capable of forming an azeotrope with water is selected from toluene, xylene and combinations thereof.  
     
     
         9 . The method of  claim 1  wherein the solvent capable of forming an azeotrope with water comprises toluene.  
     
     
         10 . The method of  claim 1  wherein the amine comprises a polyamine.  
     
     
         11 . The method of  claim 1  wherein the amine is selected from diethylenetriamine, m-xylylenediamine and combinations thereof.  
     
     
         12 . The method of  claim 1  wherein the amine comprises m-xylylenediamine.  
     
     
         13 . The method of  claim 1  wherein the amine blocker is a ketone.  
     
     
         14 . The method of  claim 13  wherein the ketone has a molecular weight in the range of about 30 to about 600.  
     
     
         15 . The method of  claim 13  wherein the ketone contains between about 3 and 14 carbon atoms.  
     
     
         16 . The method of  claim 13  wherein the ketone is selected from methyl isobutyl ketone, methyl ethyl ketone, acetone, phorone, heptanedione, tetramethylheptanedione, adamantone, acetonyl acetone, methylpropylketone and combinations thereof.  
     
     
         17 . The method of  claim 13  wherein the ketone comprises methyl isobutyl ketone.  
     
     
         18 . The method of  claim 1  wherein the amine blocker is an aldehyde.  
     
     
         19 . The method of  claim 18  wherein the aldehyde has a molecular weight in the range of about 30 to about 600.  
     
     
         20 . The method of  claim 18  wherein the aldehyde contains between about 2 and 14 carbon atoms.  
     
     
         21 . The method of  claim 18  wherein the aldehyde is selected from benzaldehyde, salicylaldehyde and combinations thereof.  
     
     
         22 . The method of  claim 18  wherein the aldehyde comprises benzaldehyde.  
     
     
         23 . The method of  claim 1  wherein the solvent capable of forming an azeotrope with water comprises toluene, the amine comprises m-xylylenediamine, and the amine blocker comprises methyl isobutyl ketone.  
     
     
         24 . The method of  claim 1  wherein the yield of blocked amine is greater than about 90% of the theoretical yield.  
     
     
         25 . The method of  claim 1  wherein the yield of blocked amine is greater than about 95% of the theoretical yield.  
     
     
         26 . The method of  claim 1  wherein the yield of blocked amine is greater than about 97% of the theoretical yield.  
     
     
         27 . The product produced by the method of  claim 1 .  
     
     
         28 . The method of  claim 1  with the proviso that the blocked amine is not the reaction product of one or more compounds containing at least one epoxy group and one or more imines having at least one amino hydrogen.  
     
     
         29 . The method of  claim 1  with the proviso that the blocked amine is not a heterocycle-containing compound having a backbone chain selected from the group consisting of polyether, polyvinyl, polyester, polyamide, polycarbonate, and novalac chains and at least two heterocyclic groups of the following general formula as side chains,  
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  may be the same or different and each represents hydrogen, straight chain or branched C 1  to C 6  alkyl or alkenyl, or C 6  to C 8  aryl; or R 1  and R 2  taken together with the adjacent carbon atom, represents C 5  to C 7  cycloalkyl: R 3  represents C 1  to C 10  alkylene.