Composition With Improved Cleanliness For Lubrication Of Steam And Gas Turbine Systems

Abstract

The present invention relates to the use of an additive composition that contains the combination of two specific types of antioxidants with one or more of four specific types of dispersants in a Group II and/or Group III base oil-containing lubricating composition. The lubricating composition of the present invention provides improved cleanliness in steam and gas turbine systems. The invention further relates to the process to make the novel additive composition and its use in industrial fluids.

1 . A lubricating oil composition comprising:
 a) an oil of lubricating viscosity comprising a Group II base oil, a Group III base oil, or combinations thereof;   b) an antioxidant component comprising:
 (i) an alkylated diphenylamine, and 
 (ii) a substituted hydrocarbyl mono-sulfide; 
   c) a dispersant component comprising at least one of:
 (i) a polyetheramine, 
 (ii) a borated succinimide dispersant, 
 (iii) a non-borated succinimide dispersant, 
 (iv) a Mannich reaction product of a dialkylamine, an aldehyde and a hydrocarbyl substituted phenol; and 
   d) optionally one or more additional additives.   
     
     
         2 . The composition of  claim 1  wherein component d) comprises a rust inhibitor, a metal deactivator, a demulsifier, an antifoam agent, or combinations thereof. 
     
     
         3 . The composition of  claim 1  wherein component b) is present in the overall composition from 0.1 to 0.9 parts by weight and component c) is present in the overall composition from 0.05 to 0.5 parts by weight. 
     
     
         4 . The composition of  claim 2  wherein the rust inhibitor comprises an amine phosphate, a fatty carboxylic acid or ester thereof, an ester of a nitrogen-containing carboxylic acid, an ammonium sulfonate, an imidazoline, or combinations thereof;
 wherein the metal deactivator comprises a triazole, a tolyltriazole, a thiadiazole, or combinations thereof; 
 wherein the demulsifier comprises a polyether; and 
 wherein the antifoam comprises an acrylate copolymer. 
 
     
     
         5 . The composition of  claim 1 , wherein the alkylated diphenylamine is 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. 
     
     
         6 . The composition of  claim 1  wherein the substituted hydrocarbyl mono-sulfides are represented by the formula: 
       
         
           
           
               
               
           
         
       
       wherein R 3  is a saturated or unsaturated branched or linear alkyl group with about 8 to about 20 carbon atoms; R 4 , R 5 , R 6  and R 7  are independently hydrogen or alkyl containing about 1 to about 3 carbon atoms. 
     
     
         7 . The composition of  claim 6 , wherein the substituted hydrocarbyl monosulfide is n-dodecyl 2-hydroxyethyl sulfide, 1-(tert-dodecylthio)-2-propanol, or mixtures thereof. 
     
     
         8 . The composition of  claim 1  wherein the dispersant component comprises a polyetheramine derived from the reaction of a mixture of alcohols containing from 10 to 18 carbon atoms, an alkoxylate and an amine;
 wherein the antioxidant component is present in the overall composition at less than 0.865 parts by weight; 
 wherein the composition is free of N-alkyl sarcosines; 
 wherein the composition contains less than 0.1 parts by weight of fatty carboxylic acids; and 
 wherein the dispersant component is present in the overall composition from 0.07 to 0.4 parts by weight. 
 
     
     
         9 . The composition of  claim 1  wherein the dispersant component comprises a borated succinimide dispersant derived from polyisobutylene having a number average molecular weight from 500 to 3000 and polyethylenepolyamines;
 wherein the dispersant component is present in the overall composition from 0.07 to less than 0.4 parts by weight. 
 
     
     
         10 . The composition of  claim 1  wherein the dispersant component comprises a non-borated succinimide dispersant derived from polyisobutylene having a number average molecular weight from 500 to 3000 and polyethylenepolyamines;
 wherein the composition contains less than 0.1 parts by weight of fatty carboxylic acids; and 
 wherein the dispersant component is present in the overall composition from 0.06 to 0.35 parts by weight. 
 
     
     
         11 . The composition of  claim 1  wherein the dispersant component comprises a Mannich reaction product derived from the reaction of a dialkylamine, formaldehyde, and a polyisobutylene substituted phenol where the polyisobutylene has a number average molecular weight from 500 to 3000; and
 wherein the dispersant component is present in the overall composition from 0.07 to 0.44 parts by weight. 
 
     
     
         12 . The lubricating composition of  claim 1 , wherein the metal deactivator is selected from the group comprising hydrocarbyl substituted benzotriazole, 5-methylbenzotriazole and mixtures thereof. 
     
     
         13 . The composition of  claim 1 , wherein the additive components b) to d) are in the range about 0 to about 13 parts by weight of the overall composition. 
     
     
         14 . A process to prepare a lubricating oil composition comprising the steps of: (I) mixing together:
 a) an oil of lubricating viscosity comprising a Group II base oil, a group III base oil, or combinations thereof;   b) an antioxidant component comprising:
 (i) an alkylated diphenylamine, and 
 (ii) a substituted hydrocarbyl mono-sulfide; 
   c) a dispersant component comprising at least one of:
 (i) a polyetheramine, 
 (ii) a borated succinimide dispersant, 
 (iii) a non-borated succinimide dispersant, 
 (iv) a Mannich reaction product of a dialkylamine, an aldehyde and a hydrocarbyl substituted phenol; 
   d) optionally other additives.   
     
     
         15 . The process of  claim 14 , wherein the antioxidant package is in the range of 0.05 to 13 parts by weight of the overall composition; the dispersant component is in the range of 0.05 to 10 parts by weight of the overall composition; the optional additives, when present, are present from 0.001 to 10 parts by weight of the overall composition; and the balance is made up of the oil of lubricating viscosity.