Inhibition of amine oxidation

Abstract

In an embodiment, an amine-oxidation inhibitor, such as a free radical scavenger and/or antioxidant, is added to an oxidation-sensitive amine, such as an amine catalyst, to inhibit oxidation of the amine. The inhibitor-treated amine may then be used in an application such as a polyurethane application to reduce the emission of undesired oxidation products from the polyurethane.

1 . A composition comprising:
 an oxidation-sensitive amine selected from one or more of an amine catalyst, a polyetheramine, an ethyleneamine, an alkoxylated amine, an alkoxylated amine, and a surfactant amine; and   an amine-oxidation inhibitor selected from a free radical scavenger, an antioxidant, or both.   
     
     
         2 . The composition of  claim 1  wherein the oxidation-sensitive amine is a tertiary amine catalyst selected from one or more of bis-(2-dimethyaminoethyl)ether, N,N,N′-trimethyl-N′-hydroxyethylbisaminoethylether, N-(3 -dimethylaminopropyl)-N,N-diisopropanolamine, N,N-dimethylethanolamine, triethylene diamine, N,N-dimethylchyclohexylamine, benzyldimethylamine, pentamethyldiethylenetriamine, N,N,N′,N,″,N″-pentamethyldipropylenetriamine, N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, N-(3 -dimethylaminopropyl)-N,N-diisopropanolamine, N′-(3 -(dimethylamino)propyl-N,N-dimethyl-dimethyl-1, 3-propanediamine, 2-(2-dimethylaminoethoxy)ethanol, N,N,N′-trimethylaminoethyl-ethanolamine, N-ethylmorpholine, N-methylmorpholine, 4-methoxyethylmorpholine, N, N′dimethylpiperazine, 2,2′dimorpholinodiethylether, 1,3,5-tris(3-(dimethylamino)propyl)-hexahydro-s-triazine, 1 -Propanamine, 3-(2-(dimethylamino)ethoxy). 
     
     
         3 . The composition of  claim 1  wherein the oxidation-sensitive amine is a polyetheramine selected from one or more of a monoamine, a diamine, a polyether diamine, an unhindered diamine, and a triamine. 
     
     
         4 . The composition of  claim 1  wherein the oxidation-sensitive amine is an ethyleneamine selected from one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, aminoethylpiperazine, aminoethylethanolamine, pentaethylenehexamine, hexaethyleneheptamine, and mixtures thereof. 
     
     
         5 . The composition of  claim 1  wherein the oxidation-sensitive amine is an alkoxylated amine selected from one or more of 2-(2-aminoethoxy)ethanol, diethanolamine, N-methyldiethanolamine, and triethanolamine. 
     
     
         6 . The composition of  claim 1  wherein the oxidation-sensitive amine is a surfactant amine selected from one or more of a polyether monoamine, a hydrophobic monoamine, and a hydrophilic polyether monoamine. 
     
     
         7 . The composition of  claim 1  wherein the amine-oxidation inhibitor is a free-radical scavenger selected from one or more of allupurinol, propyl thiouracil, glutamine, diaminobenzylamine, nicotinamide, methimazole, phenyl methimazole, and derivatives of methimazole or phenyl methimazole. 
     
     
         8 . The composition of  claim 1  wherein the amine-oxidation inhibitor is methimazole. 
     
     
         9 . The composition of  claim 1  wherein the amine-oxidation inhibitor is an antioxidant selected from one or more of a hindered phenolic, a hindered aliphatic amine, a hindered aromatic amine, a mixed phenolic, an antioxidant with triazole and phenolic group, and a natural antioxidant. 
     
     
         10 . The composition of  claim 1  wherein the amount of amine-oxidation inhibitor in the composition is from 5 ppm to 5000 ppm. 
     
     
         11 . The composition of  claim 1  wherein the amount of amine-oxidation inhibitor in the composition is 0.5% to 10% by weight of the composition. 
     
     
         12 . A method of forming an inhibitor-treated amine comprising:
 combining an oxidation-sensitive amine selected from one or more of an amine catalyst, a polyetheramine, an ethyleneamine, an alkoxylated amine, and a surfactant amine with an amine-oxidation inhibitor selected from an antioxidant, a free-radical scavenger, or both to form the inhibitor-treated amine   
     
     
         13 . The method of  claim 12  further including storing the inhibitor-treated amine in a container padded with an inert gas. 
     
     
         14 . The method of  claim 12  wherein from 5 ppm to 5000 ppm of the amine-oxidation inhibitor is combined with the oxidation-sensitive amine 
     
     
         15 . The method of  claim 12  wherein the inhibitor-treated amine and the amine-oxidation inhibitor are combined to form a blend such that the concentration of amine-oxidation inhibitor in the blend is from 0.5% to 10% by weight of the total blend. 
     
     
         16 . The method of  claim 12  further including incubating the inhibitor-treated amine at a temperature of from 0° C. to 150° C. 
     
     
         17 . The method of  claim 12  further including adding the inhibitor-treated amine to another oxidation-sensitive material selected from one or more of an isocyanate, a polyol, a prepolymer, a quasiprepolymer, and a blowing agent. 
     
     
         18 . The method of  claim 12  further including reducing the production of amine-oxidation products in the inhibitor-treated amine as compared to the same oxidation-sensitive amine that is not treated with the amine-oxidation inhibitor. 
     
     
         19 . A polyurethane product made using the composition of  claim 1 , said polyurethane product exhibiting decreased amine oxidation products as compared to the same polyurethane product made without the composition of  claim 1 .