Lubricants With Improved Seal Compatibility

Abstract

The present invention relates to lubricating compositions and particularly gear oil compositions that include a minimum level of a specific antioxidant component, where the antioxidant component includes (i) a phenolic antioxidant, (ii) an aminic antioxidant, or (iii) a combination thereof, where the antioxidant component is present in the lubricating composition at from 1.0 percent by weight or higher. Such compositions provide surprisingly good seal compatibility.

We claim: 
     
         1 . An industrial lubricating composition comprising an oil of lubricating viscosity and an antioxidant component comprising: (i) a phenolic antioxidant, (ii) an aminic antioxidant, or (iii) a combination thereof;
 wherein the antioxidant component is present in the lubricating composition at 1.0 percent by weight or higher.   
     
     
         2 . The composition of  claim 1  wherein the phenolic antioxidant is present in the lubricating composition from at least 0.5 percent by weight; and
 wherein the aminic antioxidant is present in the lubricating composition from at least 0.5 percent by weight. 
 
     
     
         3 . The composition of  claim 1  wherein the phenolic antioxidant comprises a substituted phenol containing at least one alkyl substituent group. 
     
     
         4 . The composition of  claim 1  wherein the aminic antioxidant comprises a diarylamine. 
     
     
         5 . The composition of  claim 1  wherein the oil of lubricating viscosity comprises a mineral base oil. 
     
     
         6 . The composition of  claim 1  wherein the oil of lubricating viscosity comprises a synthetic base oil. 
     
     
         7 . The composition of  claim 1  further comprising: an antiwear agent, an extreme pressure agent, a friction modifier, a corrosion inhibitor, a rust inhibitor, a metal deactivator, a borated dispersant, a non-borated dispersant, detergent, an antifoam, a viscosity index improver, a viscosity modifier, an antioxidant, a pour point depressant, a seal swell agent, or any combination thereof. 
     
     
         8 . A method of lubricating an industrial gear assembly comprising supplying to said assembly a lubricating composition comprising an oil of lubricating viscosity and an antioxidant component comprising: (i) a phenolic antioxidant, (ii) an aminic antioxidant, or (iii) a combination thereof;
 wherein the antioxidant component is present in the lubricating composition at 1.0 percent by weight or higher.   
     
     
         9 . The method of  claim 8  wherein the phenolic antioxidant is present in the lubricating composition from at least 0.5 percent by weight; and
 wherein the aminic antioxidant. antioxidant is present in the lubricating composition from at least 0.5 percent by weight. 
 
     
     
         10 . The method of  claim 8  wherein the phenolic antioxidant comprises a substituted phenol containing at least one alkyl substituent group. 
     
     
         11 . The method of  claim 8  wherein the aminic antioxidant comprises a diarylamine. 
     
     
         12 . The method of  claim 8  wherein the oil of lubricating viscosity comprises a mineral base oil. 
     
     
         13 . The method of  claim 8  wherein the oil of lubricating viscosity comprises a synthetic base oil. 
     
     
         14 . The method of  claim 8  wherein the lubricating composition further comprising: an antiwear agent, an extreme pressure agent, a friction modifier, a corrosion inhibitor, a rust inhibitor, a metal deactivator, a borated dispersant, a non-borated dispersant, detergent, an antifoam, a viscosity index improver, a viscosity modifier, an additional antioxidant, a pour point depressant, a seal swell agent, or any combination thereof. 
     
     
         15 . A method of improving the seal compatibility of an industrial gear assembly lubricant comprising adding to said lubricant composition an antioxidant component comprising: (i) a phenolic antioxidant, (ii) an aminic antioxidant, or (iii) a combination thereof;
 wherein the antioxidant component is present in the lubricant at 1.0 percent by weight or higher.   
     
     
         16 . (canceled)