Method for producing single component room temperature curable low VOC epoxy coating

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 of making a low VOC epoxy coating, comprising: 
 drying an epoxy resin and a blocked amine;    combining and mixing the epoxy resin, the blocked amine, and a first solvent to form the single component epoxy coating precursor, the single component epoxy coating precursor having a VOC level of less than about 3 lbs/gal; and    exposing the single component epoxy coating precursor to water, the single component epoxy coating precursor and water reacting to form the low VOC epoxy coating.    
     
     
         2 . The method of  claim 1  wherein the single component epoxy coating precursor has a VOC level of less than about 2.8 lbs/gal.  
     
     
         3 . The method of  claim 1  further comprising adding a reactive diluent to the single component epoxy coating precursor.  
     
     
         4 . The method of  claim 3  wherein the reactive diluent is selected from modified glycidyl ethers, acrylates, methacrylates, urethane acrylates and combinations thereof.  
     
     
         5 . The method of  claim 3  wherein the reactive diluent comprises a modified glycidyl ether.  
     
     
         6 . The method of  claim 1  further comprising adding a water scavenger to the the single component epoxy coating precursor.  
     
     
         7 . The method of  claim 6  wherein the water scavenger is selected from molecular sieves, monocyclic bifunctional oxazolidines and combinations thereof.  
     
     
         8 . The method of  claim 1  wherein the first solvent is selected from acetone, p-chlorobenzotrifluoride, t-butyl acetate, methyl isobutyl ketone, methyl propyl ketone and combinations thereof.  
     
     
         9 . The method of  claim 1  wherein the epoxy resin is selected from aliphatic epoxy resins, cycloaliphatic epoxy resins, aromatic epoxy resins and combinations thereof.  
     
     
         10 . The method of  claim 1  wherein the epoxy resin comprises a difunctional bisphenol A/epichlorohydrin derived epoxy resin.  
     
     
         11 . The method of  claim 1  wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 16 stokes.  
     
     
         12 . The method of  claim 1  wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 13 stokes.  
     
     
         13 . The method of  claim 1  wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 7 stokes.  
     
     
         14 . The method of  claim 1  wherein the blocked amine comprises a ketone-based blocked amine.  
     
     
         15 . The method of  claim 14  wherein the ketone-based blocked amine includes a ketone having a molecular weight in the range of about 30 to about 600.  
     
     
         16 . The method of  claim 14  wherein the ketone-based blocked amine includes a ketone containing between about 3 and 14 carbon atoms.  
     
     
         17 . The method of  claim 1  wherein the blocked amine comprises an aldehyde-based blocked amine.  
     
     
         18 . The method of  claim 17  wherein the aldehyde-based blocked amine includes an aldehyde having a molecular weight in the range of about 30 about 600.  
     
     
         19 . The method of  claim 17  wherein the aldehyde-based blocked amine includes an aldehyde containing between about 2 and 14 carbon atoms.  
     
     
         20 . The method of  claim 1  wherein the blocked amine comprises a methyl isobutyl ketone-xylylenediamine based blocked amine.  
     
     
         21 . The method of  claim 1  further comprising adding a pigment.  
     
     
         22 . The method of  claim 21  wherein the pigment is selected from titanium dioxide, diarylide yellow, iron oxide, raw umber, burnt umber, phthalocyanine blue, cobalt blue, chinese blue, phthalocyanine green, toluidine red, quinacridone red, dicerylide orange, carbon black, furnale black, lampblack, leafing aluminum and non-leaving aluminum.  
     
     
         23 . The method of  claim 1  wherein the blocked amine is made by a process 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.  
 
     
     
         24 . The method of  claim 23  wherein the solvent capable of forming an azeotrope with water is capable of forming a binary or ternary azeotrope with water.  
     
     
         25 . The method of  claim 23  wherein the solvent capable of forming an azeotrope with water is selected from toluene, xylene and combinations thereof.  
     
     
         26 . The method of  claim 23  wherein the solvent capable of forming an azeotrope with water comprises toluene.  
     
     
         27 . The method of  claim 23  wherein the amine comprises a polyamine.  
     
     
         28 . The method of  claim 23  wherein the amine is selected from diethylenetriamine, m-xylylenediamine and combinations thereof.  
     
     
         29 . The method of  claim 23  wherein the amine comprises m-xylylenediamine.  
     
     
         30 . The method of  claim 23  wherein the amine blocker is a ketone.  
     
     
         31 . The method of  claim 30  wherein the ketone has a molecular weight in the range of about 30 to about 600.  
     
     
         32 . The method of  claim 30  wherein the ketone contains between about 3 and 14 carbon atoms.  
     
     
         33 . The method of  claim 30  wherein the ketone is selected from methyl isobutyl ketone, methyl ethyl ketone, acetone, phorone, heptanedione, tetramethylheptanedione, adamantone, acetonyl acetone, methylpropylketone and combinations thereof.  
     
     
         34 . The method of  claim 30  wherein the ketone comprises methyl isobutyl ketone.  
     
     
         35 . The method of  claim 23  wherein the amine blocker is an aldehyde.  
     
     
         36 . The method of  claim 35  wherein the aldehyde has a molecular weight in the range of about 30 to about 600.  
     
     
         37 . The method of  claim 35  wherein the aldehyde contains between about 2 and 14 carbon atoms.  
     
     
         38 . The method of  claim 35  wherein the aldehyde is selected from benzaldehyde, salicylaldehyde and combinations thereof.  
     
     
         39 . The method of  claim 35  wherein the aldehyde comprises benzaldehyde.  
     
     
         40 . The method of  claim 23  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.  
     
     
         41 . A low VOC epoxy coating comprising: 
 a reaction product of a single component epoxy coating precursor and water, the single component epoxy coating precursor comprising an epoxy resin, a first solvent, and a blocked amine, the single component epoxy coating precursor having a VOC level of less than about 3 lbs/gal.    
     
     
         42 . The low VOC epoxy coating of  claim 41  wherein the single component epoxy coating precursor has a VOC level of less than about 2.8 lbs/gal.  
     
     
         43 . The low VOC epoxy coating of  claim 41  wherein the single component epoxy coating precursor has a viscosity after 30 days at a temperature of 55° C. of less than 16 stokes.  
     
     
         44 . The low VOC epoxy coating of  claim 41  wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 13 stokes.  
     
     
         45 . The low VOC epoxy coating of  claim 41  wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 7 stokes.  
     
     
         46 . The low VOC epoxy coating of  claim 41  wherein the epoxy resin is selected from aliphatic epoxy resins, cycloaliphatic epoxy resins, aromatic epoxy resins and combinations thereof.  
     
     
         47 . The low VOC epoxy resin coating of  claim 41  wherein the epoxy resin comprises a difunctional bisphenol A/epichlorohydrin derived epoxy resin.  
     
     
         48 . The low VOC epoxy resin coating of  claim 41  wherein the first solvent is selected from acetone, p-chlorobenzotrifluoride, t-butyl acetate, methyl isobutyl ketone, methyl propyl ketone and combinations thereof.  
     
     
         49 . The low VOC epoxy resin coating of  claim 41  wherein the blocked amine comprises a ketone-based blocked amine.  
     
     
         50 . The low VOC epoxy resin coating of  claim 49  wherein the ketone-based blocked amine includes a ketone having a molecular weight in the range of about 30 to about 600.  
     
     
         51 . The low VOC epoxy resin coating of  claim 49  wherein the ketone-based blocked amine includes a ketone containing between about 3 and 14 carbon atoms.  
     
     
         52 . The low VOC epoxy resin coating of  claim 41  wherein the blocked amine comprises an aldehyde-based blocked amine.  
     
     
         53 . The low VOC epoxy resin coating of  claim 52  wherein the aldehyde-based blocked amine includes an aldehyde having a molecular weight in the range of about 30 to about 600.  
     
     
         54 . The low VOC epoxy resin coating of  claim 52  wherein the aldehyde-based blocked amine includes an aldehyde containing between about 2 and 14 carbon atoms.  
     
     
         55 . The low VOC epoxy coating of  claim 41  wherein the blocked amine comprises a methyl isobutyl ketone-xylylenediamine based blocked amine.  
     
     
         56 . The low VOC epoxy coating of  claim 41  wherein the single component epoxy coating precursor further comprises a reactive diluent.  
     
     
         57 . The low VOC epoxy coating of  claim 56  wherein the reactive diluent is selected from modified glycidyl ethers, acrylates, methacrylates, urethane acrylates and combinations thereof.  
     
     
         58 . The low VOC epoxy coating of  claim 56  wherein the reactive diluent comprises a modified glycidyl ether.  
     
     
         59 . The low VOC epoxy coating of  claim 41  wherein the single component epoxy coating precursor further comprises a water scavenger.  
     
     
         60 . The low VOC epoxy coating of  claim 59  wherein the water scavenger is selected from molecular sieves, monocyclic bifunctional oxazolidines and combinations thereof.  
     
     
         61 . The low VOC epoxy coating of  claim 41  further comprising adding a pigment.  
     
     
         62 . The method of  claim 61  wherein the pigment is selected from titanium dioxide, diarylide yellow, iron oxide, raw umber, burnt umber, phthalocyanine blue, cobalt blue, chinese blue, phthalocyanine green, toluidine red, quinacridone red, dicerylide orange, carbon black, furnale black, lampblack, leafing aluminum and non-leaving aluminum.  
     
     
         63 . The method of  claim 1  wherein the first solvent has an intermediate polar solubility parameter and an intermediate hydrogen bonding solubility parameter.  
     
     
         64 . The low VOC epoxy resin coating of  claim 41  wherein the first solvent has an intermediate polar solubility parameter and an intermediate hydrogen bonding solubility parameter.  
     
     
         65 . 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.  
     
     
         66 . 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.  
     
     
         67 . The low VOC epoxy coating of  claim 41  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.  
     
     
         68 . The low VOC epoxy coating of  claim 41  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.