Formulation approach to extend the high temperature performance of lithium complex greases

Abstract

The present disclosure provides a lithium complex grease with high-temperature resistivity and a method of using the same. The lithium complex grease includes: a lithium complex thickener, a friction modifier, a polymer or copolymer, and at least one synthetic base oil with alkylated naphthalene. The lithium complex grease can be substantially free of polytetrafluoroethylene. Furthermore, the lithium complex grease provides a median failure rate via a ball bearing test (e.g., using the FE9 grease life test method of DIN 51 821) performed at 160° C. of no less than 100 hours.

1 . A lithium complex grease with high-temperature resistivity comprising:
 a lithium complex thickener;   a friction modifier;   a polymer or copolymer; and   at least one synthetic base oil including alkylated naphthalene;   wherein the lithium complex grease has a median failure rate with a ball bearing test performed at 160° C. (FE9 grease life test method of DIN 51 821) of no less than 100 hours.   
     
     
         2 . The lithium complex grease of  claim 1 , wherein the friction modifier is at least one of a molybdenum (Mo) friction modifier, molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), an organic molybdenum amine or amide complex, or a combination thereof. 
     
     
         3 . The lithium complex grease of  claim 1 , wherein the polymer or copolymer comprises at least one of ethylene, propylene, an ethylene-propylene co-polymer, or a combination thereof. 
     
     
         4 . The lithium complex grease of  claim 3 , wherein the polymer or copolymer is Vistamaxx™ 6202. 
     
     
         5 . The lithium complex grease of  claim 1 , wherein sufficient friction modifier is used to provide 0.1% to 2% molybdenum to the grease. 
     
     
         6 . The lithium complex grease of  claim 1 , wherein sufficient friction modifier is used to provide 0.1% to 2% sulfur to the grease. 
     
     
         7 . The lithium complex grease of  claim 1 , wherein the friction modified has a mass ratio of sulfur to molybdenum of 1 to 1.5 
     
     
         8 . The lithium complex grease of  claim 1 , wherein the at least one synthetic base oil further includes at least one of a second alkylated naphthalene base oil, a polyalphaolefin (PAO) base oil, alkylated naphthalene in PAO base oil, or a combination thereof. 
     
     
         9 . The lithium complex grease of  claim 8 , wherein the alkylated naphthalene base oil has a kinematic viscosity at 100 deg. C. ranging from 5 cSt to 19 cSt. 
     
     
         10 . The lithium complex grease of  claim 8 , wherein the PAO base oil has a kinematic viscosity at 100 deg. C. ranging from 2 cSt to 300 cSt. 
     
     
         11 . The lithium complex grease of  claim 8 , wherein the lithium complex grease has at least one of the following:
 3% to 30% of the lithium complex thickener;   0.75% to 10% of the friction modifier;   0.25% to 7% of the polymer or copolymer;   10.0% to 40% of the alkylated naphthalene base oil;   13.0% to 76% of the PAO base oil; or   a combination thereof.   
     
     
         12 . The lithium complex grease of  claim 11 , wherein the lithium complex grease has at least one of the following:
 6% to 20% of the lithium complex thickener;   1.0% to 6% of the friction modifier;   0.5% to 4% of the polymer or copolymer;   10.0% to 40% of the alkylated naphthalene base oil;   30.0% to 82.5% of the PAO base oil; or   a combination thereof.   
     
     
         13 . The lithium complex grease of  claim 1 , wherein the lithium complex grease is substantially free of polytetrafluoroethylene (PTFE), polyester (POE) base oil, or substantially free of both PTFE and POE base oil. 
     
     
         14 . The lithium complex grease of  claim 1 , further comprising at least one other grease additive selected from the group consisting of an emulsifier, a surfactant, a co-thickener, a rheology modifier, a corrosion inhibitor, an antioxidant, a wear inhibitor, an extreme pressure agent, a tackiness agent, a viscosity modifier, a colorant, an odor control agent, a filler, and a combination thereof. 
     
     
         15 . A method of improving high-temperature resistivity of a lithium complex grease used to lubricate a ball bearing, the method comprising:
 lubricating a ball bearing with a lithium complex grease comprising: a major amount of at least one synthetic base oil, wherein the at least one synthetic base oil includes alkylated naphthalene; a minor amount of a lithium complex thickener; a minor amount of a friction modifier; a minor amount of a polymer or copolymer; and the remainder of the lithium complex grease comprising one or more other grease additives; and   measuring the high-temperature resistivity of the lithium complex grease with a ball bearing test performed at 160° C. (FE9 grease life test method of DIN 51 821), wherein the lithium complex grease has a median failure rate in the ball bearing test of no less than 100 hours.   
     
     
         16 . The method of  claim 15 , wherein the at least one synthetic base oil further includes at least one of a second alkylated naphthalene base oil, a polyalphaolefin (PAO) base oil, alkylated naphthalene in PAO base oil, or a combination thereof. 
     
     
         17 . The method of  claim 16 , wherein the lithium complex grease has at least one of the following:
 3% to 30% of the lithium complex thickener;   0.75% to 10% of the friction modifier;   0.25% to 7% of the polymer or copolymer;   10.0% to 40% of the alkylated naphthalene base oil;   at least 13.0% to 76% of the PAO base oil; or   a combination thereof.   
     
     
         18 . The method of  claim 17 , wherein the lithium complex grease has at least one of the following:
 6% to 20% of the lithium complex thickener;   1.0% to 6% of the friction modifier;   0.5% to 4% of the polymer or copolymer;   10.0% to 40% of the alkylated naphthalene base oil;   30.0% to 82.5% of the PAO base oil; or   a combination thereof.   
     
     
         19 . The method of  claim 15 , wherein sufficient friction modifier is used to provide 0.1% to 2% molybdenum to the grease. 
     
     
         20 . The method of  claim 15 , wherein sufficient friction modifier is used to provide 0.1% to 2% sulfur to the grease. 
     
     
         21 . The method of  claim 15 , wherein the friction modified has a mass ratio of sulfur to molybdenum of 1 to 1.5 
     
     
         22 . The method of  claim 15 , wherein the lithium complex grease is substantially free of polytetrafluoroethylene (PTFE), polyester (POE) base oil, or substantially free of both PTFE and POE base oil. 
     
     
         23 . The method of  claim 15 , wherein the lithium complex grease further comprises at least one other grease additive selected from the group consisting of an emulsifier, a surfactant, a co-thickener, a rheology modifier, a corrosion inhibitor, an antioxidant, a wear inhibitor, an extreme pressure agent, a tackiness agent, a viscosity modifier, a colorant, an odor control agent, a filler, and a combination thereof. 
     
     
         24 . A lithium complex grease comprising:
 a major amount of at least one synthetic base oil, wherein the at least one synthetic base oil includes alkylated naphthalene;   a minor amount of a lithium complex thickener;   a minor amount of a friction modifier;   a minor amount of a polymer or copolymer; and   the remainder of the lithium complex grease comprising one or more other grease additives;   wherein the lithium complex grease has a median failure rate with a ball bearing test performed at 160° C. (FE9 grease life test method of DIN 51 821) of no less than 100 hours.   
     
     
         25 . The lithium complex grease of  claim 24 , wherein the friction modifier is at least one of a molybdenum (Mo) friction modifier, molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), an organic molybdenum amine or amide complex, or a combination thereof. 
     
     
         26 . The lithium complex grease of  claim 24 , wherein the polymer or copolymer comprises at least one of ethylene, propylene, an ethylene-propylene co-polymer, or a combination thereof. 
     
     
         27 . The lithium complex grease of  claim 24 , wherein the at least one synthetic base oil further includes at least one of a second alkylated naphthalene base oil, a polyalphaolefin (PAO) base oil, alkylated naphthalene in PAO base oil, or a combination thereof. 
     
     
         28 . The lithium complex grease of  claim 27 , wherein the lithium complex grease has at least one of the following:
 3% to 30% of the lithium complex thickener;   0.75% to 10% of the friction modifier;   0.25% to 7% of the polymer or copolymer;   10.0% to 40% of the alkylated naphthalene base oil;   at least 13.0% to 76% of the PAO base oil; or   a combination thereof.   
     
     
         29 . The lithium complex grease of  claim 24 , wherein the one or more other grease additives are selected from the group consisting of an emulsifier, a surfactant, a co-thickener, a rheology modifier, a corrosion inhibitor, an antioxidant, a wear inhibitor, an extreme pressure agent, a tackiness agent, a viscosity modifier, a colorant, an odor control agent, and a filler.