Gear oil compositions, methods of making and using thereof

Abstract

A gear oil composition is provided. The composition comprises a sufficient amount of an isomerized base oil in a base oil matrix comprising at least at least a polyalphaolefin for the gear oil composition to have for the gear oil composition to have an average volume change in a rubber seal between −10 and +10, a change in shore A hardness between −7 and +10 when tested with SRE NBR28 at 100° C., 168 hours per DIN53521 and DIN53505, a viscosity increase of less than 3% per US Steel S-200 oxidation stability test, a precipitation of less than 1% per US Steel S-200 oxidation stability test, and a Timken OK Load of greater than 60 lb. The isomerized base oil has consecutive numbers of carbon atoms and less than 10 wt % naphthenic carbon by n-d-M. In one embodiment, the sufficient amount of isomerized base oil ranges from 20 to 75 wt. % based on the total weight of the gear oil composition.

1 . A gear oil composition, comprising:
 a) a base oil comprising a mixture of at least a polyalphaolefin (PAO) base stock and at least an isomerized base oil having consecutive numbers of carbon atoms, less than 0.05 wt. % aromatics, a wt % total molecules with cycloparaffinic functionality greater than 25 and a ratio of molecules with monocycloparaffinic functionality to molecules with multicycloparaffinic functionality greater than 10;   b) 0.001 to 30 wt % at least an additive selected from traction reducers, dispersants, viscosity modifiers, pour point depressants, antifoaming agents, antioxidants, rust inhibitors, metal passivators, extreme pressure agents, friction modifiers, and mixtures thereof;   wherein the isomerized base oil base stock is present in a sufficient amount for the gear oil composition to have an average volume change in a rubber seal between −10 and +10, and a change in shore A hardness between −7 and +10 when tested with SRE NBR28 at 100° C., 168 hours per DIN53521 and DIN53505.   
   
   
       2 . The gear oil composition of  claim 1 , wherein the isomerized base oil base stock is present in a sufficient amount for the gear oil composition to have an average volume change in a rubber seal between −5 and +5, and a change in shore A hardness between −5 and +5 when tested with SRE NBR28 at 100° C., 168 hours per DIN53521 and DIN53505. 
   
   
       3 . The gear oil composition of  claim 2 , wherein the isomerized base oil base stock is present in an amount of 30 to 40 wt. % based on the total weight of the gear oil composition. 
   
   
       4 . The gear oil composition of  claim 3 , wherein the isomerized base oil has a kinematic viscosity at 100° C. of 3 to 8 mm 2 /s., a viscosity index of 145-165, Oxidator BN of 15 to 55 hours; and wherein the polyalphaolefin base stock has a kinematic viscosity of about 40 mm 2 /s at 100° C. 
   
   
       5 . The gear oil composition of  claim 1 , wherein the composition has a viscosity increase of less than 3% per US Steel S-200 oxidation stability test. 
   
   
       6 . The gear oil composition of  claim 5 , wherein the composition has a viscosity increase of less than 2% per US Steel S-200 oxidation stability test 
   
   
       7 . The gear oil composition of  claim 6 , wherein the composition has a viscosity increase of less than 1% when tested per US Steel S-200 oxidation stability test 
   
   
       8 . The gear oil composition of  claim 1 , wherein the composition has a precipitation of less than 1% per US Steel S-200 oxidation stability test. 
   
   
       9 . The gear oil composition of  claim 9 , wherein the composition has a precipitation of less than 0.05% per US Steel S-200 oxidation stability test. 
   
   
       10 . The gear oil composition of  claim 9 , wherein the composition has a precipitation of less than 0.03% per US Steel S-200 oxidation stability test. 
   
   
       11 . The gear oil composition of  claim 1 , wherein the composition has a Timken OK Load of greater than 60 lb. 
   
   
       12 . The gear oil composition of  claim 1 , wherein the composition has a Timken OK Load of greater than 70 lb. 
   
   
       13 . The gear oil composition of  claim 1 , wherein the composition has a viscosity increase of less than 3% per US Steel S-200 oxidation stability test, a precipitation of less than 1% per US Steel S-200 oxidation stability test, and a Timken OK Load of greater than 60 lb. 
   
   
       14 . The gear oil composition of  claim 13 , wherein the isomerized base oil is present in an amount of 40 to 80 wt. % based on the total weight of the gear oil composition. 
   
   
       15 . The gear oil composition of  claim 13 , wherein the isomerized base oil Has a kinematic viscosity at 100° C. of 10 to 20 mm 2 /s., a viscosity index of 155-165, Oxidator BN of 15 to 25 hours; and wherein polyalphaolefin base stock has a kinematic viscosity of about 40-100 mm 2 /s at 100° C. 
   
   
       16 . The composition of  claim 1 , wherein the isomerized base oil has a total weight percent of molecules with cycloparaffinic functionality of greater than 10, and a ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality of greater than 15. 
   
   
       17 . The composition of  claim 1 , wherein the isomerized base oil is made from a process in which the highly paraffinic wax is hydroisomerized using a shape selective intermediate pore size molecular sieve comprising a noble metal hydrogenation component, and under conditions of about 600° F. to 750° F. and wherein the isomerized base oil has a Noack volatility of less than 50 weight %. 
   
   
       18 . The composition of  claim 1 , wherein the isomerized base oil has a Noack volatility less than an amount calculated by: 1.286+20 (kv100) −1.5 +551.8 e −kv100 , where kv100 is the kinematic viscosity at 100° C. 
   
   
       19 . The composition of  claim 1 , wherein the isomerized base oil comprises greater than 3 weight % molecules with cycloparaffinic functionality and less than 0.30 weight percent aromatics. 
   
   
       20 . The composition of  claim 1 , wherein the isomerized base oil comprises greater than 10 wt. % and less than 70 wt. % total molecules with cycloparaffinic functionality 
   
   
       21 . A method for improving the oxidative stability and seal compatibility properties of a gear oil composition, the method comprises adding a sufficient amount of at least an isomerized base oil to a base oil matrix comprising at least a polyalphaolefin, for the gear oil composition to have an average volume change in a rubber seal between −10 and +10, a change in shore A hardness between −7 and +10 when tested with SRE NBR28 at 100° C., 168 hours per DIN53521 and DIN53505, and a viscosity increase of less than 3% per US Steel S-200 oxidation stability test. 
   
   
       22 . The method of  claim 21 , wherein the isomerized base oil is present in an amount from 20 to 75 wt. % based on the total weight of the gear oil composition.