Power transmission fluid with enhanced friction characteristics

Abstract

A power transmission fluid composition, a power transmission containing the fluid, a method of operating a power transmission with the fluid and method of improving friction durability for a power transmission fluid. The power transmission fluid includes (a) a base oil and (b) an additive composition having therein (i) at least one ashless dispersant; (ii) a metal detergent providing greater than about 100 ppm metal in the power transmission fluid composition; (iii) a friction modifying amount of an imidazoline; (iv) a succinimide friction modifier; and (v) a non-hydroxy tertiary amine friction modifier other than (iii).

1 . A power transmission fluid composition comprising: (a) a base oil and (b) an additive composition comprising (i) at least one ashless dispersant; (ii) a metal detergent providing greater than about 100 ppm metal to the transmission fluid composition; (iii) a friction modifying amount of an imidazoline; (iv) a succinimide friction modifier; and (v) a non-hydroxy tertiary amine friction modifier other than (iii). 
     
     
         2 . The fluid of  claim 1 , wherein the base oil comprises a natural lubricating oil, a mixture of natural lubricating oils, a synthetic oil, a mixture of synthetic oils, or a mixture of natural and synthetic oils. 
     
     
         3 . The fluid of  claim 2 , wherein the synthetic oil or mixture of synthetic oils comprises an oligomer of an alphaolefin, an ester, an oil derived from a gas-to-liquid process such as a Fischer-Tropsch process, or a mixture thereof. 
     
     
         4 . The fluid of  claim 1 , wherein the ashless dispersant comprises a boronated/phosphorylated dispersant. 
     
     
         5 . The fluid of  claim 1 , wherein the dispersant comprises about 0.1 wt % to about 0.7 wt % of boron. 
     
     
         6 . The fluid of  claim 1 , wherein the ashless dispersant comprises a hydrocarbyl substituted succinimide derived from polyisobutylene having a molecular weight ranging from about 700 amu to about 3000 amu. 
     
     
         7 . The fluid of  claim 1 , wherein the additive composition comprises from about 20 wt % to about 65.0 wt % of the dispersant. 
     
     
         8 . The fluid of  claim 1 , further comprising a hydrocarbyl-substituted succinimide wherein the hydrocarbyl group has a molecular weight ranging from about 500 amu to about 1200 amu. 
     
     
         9 . The fluid of  claim 1 , wherein the metal detergent comprises a detergent selected from the group consisting of an overbased calcium sulfonate detergent, an overbased calcium phenate detergent, and mixtures thereof. 
     
     
         10 . The fluid of  claim 9 , wherein the additive composition comprises from about 1.0 to about 10.0 weight percent of the succinimide friction modifier. 
     
     
         11 . The fluid of  claim 1 , wherein the amount of imidazoline in the additive composition ranges from about 0.05 to about 1.0 weight percent. 
     
     
         12 . The fluid of  claim 1 , further comprising a sulfurized fatty acid. 
     
     
         13 . The fluid of  claim 1 , further comprising one or more of an antioxidant, a corrosion inhibitor, a metal deactivator, an antifoam agent, a viscosity index improver, a rust inhibitor, and a pour point depressant. 
     
     
         14 . The fluid of  claim 1 , wherein the imidazoline comprises a C 18 -C 22  unsaturated fatty acid hydroxyalkyl imidazoline. 
     
     
         15 . The fluid of  claim 1 , wherein the fluid is suitable for use in a transmission employing one or more of a slipping torque converter, a lock-up torque converter, a starting clutch and one or more shifting clutches. 
     
     
         16 . A method of improving friction durability in a transmission: adding to a base oil an additive composition comprising (a) at least one ashless dispersant; (b) a metal detergent providing greater than about 100 ppm metal to a fully formulated transmission fluid containing the base oil and additive composition; (c) a friction modifying amount of a hydroxyalkyl imidazoline; (d) a succinimide friction modifier; and (e) a non-hydroxy tertiary amine friction modifier other than (c). 
     
     
         17 . The method of  claim 16 , wherein the ashless dispersant comprises a boronated/phosphorylated dispersant. 
     
     
         18 . The method of  claim 16 , wherein the ashless dispersant comprises a hydrocarbyl substituted succinimide derived from polyisobutylene having a molecular weight ranging from about 1300 amu to about 3000 amu. 
     
     
         19 . The method of  claim 16 , wherein the additive composition comprises from about 20 wt % to about 65 wt % of the dispersant. 
     
     
         20 . The method of  claim 16 , wherein the metal detergent comprises a detergent selected from the group consisting of an overbased calcium sulfonate detergent, an overbased calcium phenate detergent, and mixtures thereof. 
     
     
         21 . The method of  claim 16 , wherein the additive composition comprises from about 1.0 to about 10.0 weight percent of succinimide friction modifier. 
     
     
         22 . The method of  claim 16 , wherein the amount of imidazoline in the additive composition ranges from about 0.05 to about 1.0 weight percent. 
     
     
         23 . The method of  claim 16 , wherein the imidazoline comprises a C 18 -C 22  unsaturated fatty acid hydroxyalkyl imidazoline 
     
     
         24 . The method of  claim 16 , further comprising a sulfurized fatty acid. 
     
     
         25 . A method of lubricating a transmission comprising adding to the transmission a lubricating composition comprising an oil of lubricating viscosity including an additive composition comprising:
 (a) at least one ashless dispersant;   (b) a metal detergent providing greater than about 100 ppm metal in the lubricating composition;   (c) a friction modifying amount of a C 18 -C 22  unsaturated fatty acid imidazoline;   (d) a succinimide friction modifier; and   (e) a non-hydroxy tertiary amine friction modifier other than (c).   
     
     
         26 . The method of  claim 25 , wherein the ashless dispersant comprises a boronated/phosphorylated dispersant. 
     
     
         27 . The method of  claim 25 , wherein the ashless dispersant comprises a hydrocarbyl substituted succinimide derived from polyisobutylene having a molecular weight ranging from about 1300 amu to about 3000 amu and a hydrocarbyl substituted succinimide derived from polyisobutylene having a molecular weight ranging from about 300 amu to about 1000 amu. 
     
     
         28 . The method of  claim 27 , wherein the additive composition comprises from about 20 wt % to about 65 wt % of the dispersant. 
     
     
         29 . The method of  claim 25 , wherein the metal detergent comprises a detergent selected from the group consisting of an overbased calcium sulfonate detergent, an overbased calcium phenate detergent, and mixtures thereof. 
     
     
         30 . The method of  claim 25 , wherein the additive composition comprises from about 1.0 to about 10.0 weight percent of succinimide friction modifier. 
     
     
         31 . The method of  claim 25 , wherein the amount of imidazoline in the additive composition ranges from about 0.05 to about 1.0 weight percent. 
     
     
         32 . The method of  claim 25 , wherein the imidazoline comprises a hydroxyalkyl imidazoline. 
     
     
         33 . The method of  claim 25 , further comprising one or more of an antioxidant, a corrosion inhibitor, a metal deactivator, an antifoam agent, a viscosity index improver, a rust inhibitor, an extreme pressure agent, and a pour point depressant. 
     
     
         34 . An additive concentrate for a power transmission fluid, the additive concentrate comprising at least one ashless dispersant; a metal detergent providing greater than about 100 ppm metal to the transmission fluid composition; a friction modifying amount of an imidazoline; a succinimide friction modifier; and a non-hydroxy tertiary amine friction modifier other than the imidazoline. 
     
     
         35 . The additive concentrate of  claim 34 , wherein the ashless dispersant comprises a boronated/phosphorylated dispersant. 
     
     
         36 . The additive concentrate of  claim 34 , wherein the dispersant comprises about 0.1 wt % to about 2.0 wt % of boron. 
     
     
         37 . The additive concentrate of  claim 34 , wherein the ashless dispersant comprises a hydrocarbyl substituted succinimide derived from polyisobutylene having a molecular weight ranging from about 1300 amu to about 3000 amu. 
     
     
         38 . The additive concentrate of  claim 34 , wherein the additive composition comprises from about 20 wt % to about 65 wt % of the dispersant. 
     
     
         39 . The additive concentrate of  claim 34 , further comprising a hydrocarbyl-substituted succinimide wherein the hydrocarbyl group has a molecular weight ranging from about 500 amu to about 1200 amu. 
     
     
         40 . The additive concentrate of  claim 34 , wherein the metal detergent comprises a detergent selected from the group consisting of an overbased calcium sulfonate detergent, an overbased calcium phenate detergent, and mixtures thereof. 
     
     
         41 . The additive concentrate of  claim 34 , wherein the additive composition comprises from about 1.0 to about 10.0 weight percent of the succinimide friction modifier. 
     
     
         42 . The additive concentrate of  claim 34 , wherein the amount of imidazoline in the additive composition ranges from about 0.05 to about 1.0 weight percent. 
     
     
         43 . The additive concentrate of  claim 34 , further comprising a sulfurized fatty acid. 
     
     
         44 . The additive concentrate of  claim 34 , further comprising one or more of an antioxidant, a corrosion inhibitor, a metal deactivator, an antifoam agent, a viscosity index improver, a rust inhibitor, and a pour point depressant. 
     
     
         45 . The additive concentrate of  claim 34 , wherein the imidazoline comprises a C 18 -C 22  unsaturated fatty acid hydroxyalkyl imidazoline.