Lubricating Compositions For Turbine And Hydraulic Systems With Improved Antioxidancy

Abstract

The present invention relates to a synergistic combination of an antioxidant and an antiwear additive that results in improved antioxidancy performance in turbine, hydraulic, and other industrial lubricating compositions. The invention further relates to the processes to make the improved lubricating compositions and methods of their use in industrial fluids.

We claim: 
     
         1 . A composition comprising:
 a) an oil of lubricating viscosity;   b) an aromatic amine antioxidant; and   c) a dithiocarbamate antiwear agent;   wherein component b) is present from 0.35 to 0.75 percent by weight, component c) is present from 0.25 to 0.75 percent by weight, and the total weight percent of the combination of components b) and c) is from 0.60 to 1.25 percent by weight, with regards to the overall composition;   wherein the composition is an industrial lubricant.   
     
     
         2 . The composition of  claim 1  further comprising: an antioxidant other than component b); an antiwear agent other than component c); a corrosion inhibitor, a rust inhibitor, a foam inhibitor, a dispersant, a demulsifier, a metal deactivator, a friction modifier, a detergent, a demulsifier, an extreme pressure agent, a pour point depressant, a viscosity modifier, or any combination thereof. 
     
     
         3 . The composition of  claim 1  wherein component a) comprises a Group I base oil, a Group II base oil, a Group III base oil, a poly(alpha-olefin), a GTL oil, or any combination thereof. 
     
     
         4 . The composition of  claim 1  wherein component b) comprises an alkylated diphenylamine, a phenyl-naphthylamine, an alkylated phenyl-naphthylamine, or a combination thereof; and
 wherein component c) comprises an ashless dithiocarbamate. 
 
     
     
         5 . The composition of  claim 1  wherein component b) is present from about 0.4 to about 0.7 percent by weight in the overall composition; and component c) is present from about 0.3 to 0.7 percent by weight in the overall composition; and wherein the total weight percent of the combination of components b) and c) is from 0.8 to 1.2 percent by weight, with regards to the overall composition. 
     
     
         6 . The composition of  claim 1  wherein component a) comprises a Group I base oil, a Group II base oil, a Group III base oil, or any combination thereof and is present from about 95 to about 99.9 percent by weight of the overall composition;
 wherein component b) comprises an alkylated diphenylamine and is present from about 0.4 to about 0.7 percent by weight in the overall composition; 
 wherein component c) comprises a dithiocarbamate ester and is present from about 0.3 to about 0.7 percent by weight in the overall composition; 
 wherein the total weight percent of the combination of components b) and c) is from 0.8 to 1.2 percent by weight, with regards to the overall composition; 
 wherein the composition further comprises d) an antioxidant other than component b) that is present from about 0.01 to about 5.0 percent by weight of the overall composition; 
 wherein the composition further comprises e) an antiwear additive other than component c) that is present from about 0.01 to about 2.5 percent by weight of the overall composition; 
 wherein the composition further comprises f) a corrosion inhibitor or metal deactivator that is present from about 0.001 to about 2.0 percent by weight of the overall composition; 
 wherein the composition further comprises g) a rust inhibitor, wherein component f) and component g) are different additives, where component g) is present from about 0.001 to about 2.0 percent by weight of the overall composition; 
 wherein the composition further comprises h) an antifoam additive that is present from about 0.01 to about 3.0 percent by weight of the overall composition. 
 
     
     
         7 . The composition of  claim 6  wherein component d) comprises a sulfurized olefin;
 wherein component e) comprises an amine phosphate; 
 wherein component f) comprises a triazole, a tolyltriazole, or combinations thereof; 
 wherein component g) comprises a polyether, a fatty carboxylic acid or ester thereof, an ester of a nitrogen-containing carboxylic acid, an ammonium sulfonate, an imidazoline, or combinations thereof; 
 wherein component h) comprises an acrylate copolymer. 
 
     
     
         8 . The composition of  claim 1  wherein component b), the aromatic amine antioxidant, comprises an alkylated diphenylamine represented by the formula: 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are independently a hydrogen or an alkyl group containing about 5 to 20 carbon atoms; or a linear or branched alkyl group containing 1 to 24 carbon atoms and q and r are each independently 0, 1, 2, or 3, provided that the sum of q and r is at least one. 
     
     
         9 . The composition of  claim 1  wherein component c), the dithiocarbamate antiwear agent, comprises a dithiocarbamate ester represented by the formula: 
       
         
           
           
               
               
           
         
       
       wherein R 3  and R 4  are independently alkyl of 1 to about 7 carbons, aryl, aralkyl or together form an alicyclic or heteroalicyclic radical in which the ring is completed through the nitrogen; X is O or S; a is 1 or 2; R 5  and R 6  are independently H, alkyl or aryl; and Z is —CN, —S(═O)—R 7 , —S(═O)(═O)—R 7 , or —S(═O)(═O)—O—R 7 , wherein R 7  is hydrogen, alkyl, aralkyl, or —C(═O)—Y wherein Y is —H, —OH, or —R 8  where R 8  is alkyl, aryl, aralkyl, —O—R 8 , —O—R 9 —OH, where R 9  is alkylene of 1 to about 7 carbon atoms, or —NR 10 R 11  where R 10  and R 11  are independently hydrogen, alkyl, cycloaliphatic, heteroalicyclic or together form an alicyclic or heteroalicyclic radical in which the ring is completed through the nitrogen; with the proviso that when a is 1, Y is not —O—R 8 . 
     
     
         10 . The composition of  claim 6  wherein component d), the additional antioxidant, comprises a substituted hydrocarbyl mono-sulfide represented by the formula: 
       
         
           
           
               
               
           
         
       
       wherein R 6  is a saturated or unsaturated branched or linear alkyl group with about 8 to about 20 carbon atoms; R 7 , R 8 , R 9  and R 10  are independently hydrogen or alkyl containing about 1 to about 3 carbon atoms. 
     
     
         11 . A process to prepare an industrial lubricant composition comprising the steps of: (I) mixing together:
 a) an oil of lubricating viscosity;   b) an aromatic amine antioxidant; and   c) a dithiocarbamate antiwear agent; and   optionally one or more additional additives;   wherein component b) is present from 0.5 to 0.75 percent by weight, component c) is present from 0.25 to 0.75 percent by weight, and the total weight percent of the combination of components b) and c) is from 0.75 to 1.25 percent by weight, with regards to the overall composition.   
     
     
         12 . The process of  claim 11  wherein component a) comprises a Group I base oil, a Group II base oil, a Group III base oil, or any combination thereof and is present from about 95 to about 99.9 percent by weight of the overall composition;
 wherein component b) comprises an alkylated diphenylamine and is present from about 0.4 to about 0.7 percent by weight in the overall composition; 
 wherein component c) comprises a dithiocarbamate ester and is present from about 0.3 to about 0.7 percent by weight in the overall composition; 
 wherein the total weight percent of the combination of components b) and c) is from 0.8 to 1.2 percent by weight, with regards to the overall composition; 
 wherein the composition further comprises d) an antioxidant other than component b) that is present from about 0.01 to about 5.0 percent by weight of the overall composition; 
 wherein the composition further comprises e) an antiwear additive other than component c) that is present from about 0.01 to about 2.5 percent by weight of the overall composition; 
 wherein the composition further comprises f) a corrosion inhibitor or metal deactivator that is present from about 0.001 to about 2.0 percent by weight of the overall composition; 
 wherein the composition further comprises g) a rust inhibitor, wherein component f) and component g) are different additives, where component g) is present from about 0.001 to about 2.0 percent by weight of the overall composition; 
 wherein the composition further comprises h) an antifoam additive that is present from about 0.01 to about 3.0 percent by weight of the overall composition. 
 
     
     
         13 . The process of  claim 12  wherein component d) comprises a sulfurized olefin;
 wherein component e) comprises an amine phosphate; 
 wherein component f) comprises a triazole, a tolyltriazole, or combinations thereof; 
 wherein component g) comprises a polyether, a fatty carboxylic acid or ester thereof, an ester of a nitrogen-containing carboxylic acid, an ammonium sulfonate, an imidazolines, or combinations thereof; 
 wherein component h) comprises an acrylate copolymer. 
 
     
     
         14 . A method of lubricating a turbine system comprising the steps:
 I. supplying to a turbine system a lubricating composition comprising:
 a) an oil of lubricating viscosity; 
 b) an aromatic amine antioxidant; and 
 c) a dithiocarbamate antiwear agent; 
 wherein component b) is present from 0.5 to 0.75 percent by weight, component c) is present from 0.25 to 0.75 percent by weight, and the total weight percent of the combination of components b) and c) is from 0.75 to 1.25 percent by weight, with regards to the overall composition. 
   
     
     
         15 . A method of lubricating a hydraulic system comprising the steps:
 I. supplying to a turbine system a lubricating composition comprising:
 a) an oil of lubricating viscosity; 
 b) an aromatic amine antioxidant; and 
 c) a dithiocarbamate antiwear agent; 
 wherein component b) is present from 0.5 to 0.75 percent by weight, component c) is present from 0.25 to 0.75 percent by weight, and the total weight percent of the combination of components b) and c) is from 0.75 to 1.25 percent by weight, with regards to the overall composition.