Hydraulic oil compositions with improved hydrolytic and thermo-oxidative stability

Abstract

The present disclosure provides a lubricating composition that includes at least one lubricating base oil, an effective amount of at least one overbased detergent; and an effective amount of at least one thermally stable zinc dialkyl dithiophosphate. The disclosure further provides methods of making and using the same.

1 . A hydraulic oil composition comprising:
 at least one lubricating base oil;   an effective amount of at least one overbased detergent; and   an effective amount of at least one thermally stable zinc dialkyl dithiophosphate (ZDDP).   
     
     
         2 . The composition of  claim 1 , wherein at least one of:
 the effective amount of the overbased detergent is no greater than about 3 wt. %;   the effective amount of the thermally stable ZDDP ranges from about 0.01 wt. % to about 3 wt. %; or   a combination thereof.   
     
     
         3 . The composition of  claim 1 , wherein at least one of:
 the overbased detergent includes at least one of calcium, magnesium, sodium, barium, or a combination thereof;   the overbased detergent is at least one of an overbased sulfonate, an overbased phenate, an overbased salicylate, or a combination thereof; or   a combination thereof.   
     
     
         4 . The composition of  claim 1 , wherein the overbased detergent includes at least one of overbased sulfurized calcium phenate detergent, overbased magnesium sulfonate detergent, overbased calcium phenate detergent, overbased calcium sulfonate detergent, or a combination thereof. 
     
     
         5 . The composition of  claim 1 , wherein the thermally stable ZDDP includes at least one of a primary ZDDP, a branched primary ZDDP, or a combination thereof. 
     
     
         6 . The composition of  claim 1 , wherein the lubricating base oil or oils comprise at least one of: a Group I oil, a Group II oil, a Group III oil, a Group IV oil, a Group V oil, a gas-to-liquid oil, a polyalphaolefin, or combinations thereof. 
     
     
         7 . The composition of  claim 1 , wherein the lubricating base oil or oils include at least one Group II oil. 
     
     
         8 . The composition of  claim 1  further comprising at least one of a dispersant, an additional antiwear agent, a corrosion inhibitor, a rust inhibitor, an additional detergent, an anti-seizure agent, an antifoam agent or defoamant, a wax modifier, a metal deactivator/passivator, an extreme pressure additive, an antioxidant, a viscosity index improver, a viscosity improver/modifier, a seal compatibility agent, a pour point depressant, a friction modifier, a lubricity agent, an anti-staining agent, a dye or colorant/chromophoric agent, a demulsifier, a wetting agent, an oxidation inhibitor, a tackiness agent, a colorant, a detergent stabilizer, or combinations thereof. 
     
     
         9 . The composition of  claim 8 , wherein the dispersant includes succinimide-type dispersant. 
     
     
         10 . The composition of  claim 1 , wherein the hydraulic oil composition results in at least one of improved hydrolytic stability, improved thermo-oxidative stability, decreased metal corrosion (such as, yellow metal corrosion), or a combination thereof, in a hydraulic motor relative to a hydraulic oil composition that does not include the effective amount of the overbased detergent and/or the thermally stable ZDDP. 
     
     
         11 . A method of making a hydraulic oil composition with at least one of improved hydrolytic stability, improved thermo-oxidative stability, decreased metal corrosion (such as, yellow metal corrosion), or a combination thereof, the method comprising mixing:
 at least one lubricating base oil;   at least one overbased detergent in an amount no greater than about 3 wt. %; and   at least one thermally stable ZDDP in an amount from about 0.01 wt. % to about 3 wt. %.   
     
     
         12 . The method of  claim 11 , wherein at least one of:
 the overbased detergent is present in an amount of from about 0.001 wt. % to about 1.5 wt. %;   the thermally stable ZDDP is present in an amount from about 0.05 wt. % to about 2 wt. %; or   a combination thereof.   
     
     
         13 . The method of 11, wherein at least one of:
 the thermally stable ZDDP is a primary thermally stable ZDDP;   the overbased detergent includes calcium, magnesium, sodium or barium;   the overbased detergent is at least one of an overbased sulfonate, an overbased phenate, an overbased salicylate, or a combination thereof;   the lubricating base oil or oils comprises at least one of: a Group I oil, a Group II oil, a Group III oil, a Group IV oil, a Group V oil, a gas-to-liquid oil, a polyalphaolefin, or combinations thereof;   the composition further comprises at least one of a dispersant, an additional antiwear agent, a corrosion inhibitor, a rust inhibitor, an additional detergent, an anti-seizure agent, an antifoam agent or defoamant, a wax modifier, a metal deactivator/passivator, an extreme pressure additive, an antioxidant, a viscosity index improver, a viscosity improver/modifier, a seal compatibility agent, a pour point depressant, a friction modifier, a lubricity agent, an anti-staining agent, a dye or colorant/chromophoric agent, a demulsifier, a wetting agent, an oxidation inhibitor, a gelling agent, a tackiness agent, a colorant, a detergent stabilizer, or combinations thereof; or   a combination thereof.   
     
     
         14 . A hydraulic oil composition produced according to  claim 11 . 
     
     
         15 . A method for lubricating a hydraulic motor requiring a hydraulic oil composition, the method comprising:
 supplying the hydraulic motor with a hydraulic oil composition comprising:   at least one lubricating base oil;   
       an effective amount of at least one overbased detergent; and
 an effective amount of at least one thermally stable ZDDP. 
 
     
     
         16 . The method of  claim 15 , wherein at least one of:
 the effective amount of the overbased detergent is no greater than about 3 wt. %;   the effective amount of the thermally stable ZDDP ranges from about 0.01 wt. % to about 3 wt. %; or   a combination thereof.   
     
     
         17 . The method of  claim 15 , wherein at least one of:
 the thermally stable ZDDP is a primary thermally stable ZDDP;   the overbased detergent includes calcium, magnesium, sodium or barium;   the overbased detergent is at least one of an overbased sulfonate, an overbased phenate, an overbased salicylate, or a combination thereof;   the lubricating base oil or oils comprises at least one of: a Group I oil, a Group II oil, a Group III oil, a Group IV oil, a Group V oil, a gas-to-liquid oil, a polyalphaolefin, or combinations thereof;   the composition further comprises at least one of a dispersant, an additional antiwear agent, a corrosion inhibitor, a rust inhibitor, an additional detergent, an anti-seizure agent, an antifoam agent or defoamant, a wax modifier, a metal deactivator/passivator, an extreme pressure additive, an antioxidant, a viscosity index improver, a viscosity improver/modifier, a seal compatibility agent, a pour point depressant, a friction modifier, a lubricity agent, an anti-staining agent, a dye or colorant/chromophoric agent, a demulsifier, a wetting agent, an oxidation inhibitor, a gelling agent, a tackiness agent, a colorant, a detergent stabilizer, or combinations thereof; or   a combination thereof.   
     
     
         18 . The method of  claim 15 , wherein the lubricating base oil or oils are Group II oil. 
     
     
         19 . The method of  claim 15 , wherein the method results in at least one of improved hydrolytic stability, improved thermo-oxidative stability, decreased metal corrosion (such as, yellow metal corrosion), or a combination thereof, in the hydraulic motor relative to a method using a hydraulic oil composition that does not include the effective amount of the overbased detergent and/or the thermally stable ZDDP. 
     
     
         20 . A hydraulic oil composition produced according to  claim 15 .