Lubricating Oil Composition

Abstract

A lubricating oil composition containing a combination of oil of lubricating viscosity, one or more block copolymers of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly(conjugated diene) as a viscosity modifier, and one or more one or more optionally substituted bridged hydrocarbyl phenol condensates, or metal salts thereof, as a detergent.

1 . A lubricating oil composition comprising a major amount of oil of lubricating viscosity, and minor amounts of a viscosity modifier comprising one or more block copolymers of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly(conjugated diene) and one or more detergents comprising one or more optionally substituted bridged hydrocarbyl phenol condensates, or metal salts thereof. 
     
     
         2 . A lubricating composition according to  claim 1  wherein the monovinyl aromatic hydrocarbon block of said block copolymer of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly(conjugated diene) is derived from monomer containing from 8 to about 16 carbon atoms selected from the group consisting of aryl-substituted styrene, alkoxy-substituted styrene, vinyl naphthalene and alkyl-substituted vinyl naphthalene. 
     
     
         3 . A lubricating composition according to  claim 1  wherein the conjugated diene block of said block copolymer of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly(conjugated diene) is derived from monomer containing 2 to 16 carbon atoms selected from the group consisting of 1,3-butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4-dimethyl-1,3-hexadiene, and 4,5-diethyl-1,3-octadiene. 
     
     
         4 . A lubricating oil composition according to  claim 1  wherein said block copolymer of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly(conjugated diene) is represented by the following formula:
   A z -(B-A) y -B x      
       wherein: A is a polymeric block derived predominantly from vinyl aromatic hydrocarbon monomer; B is a polymeric block derived predominantly from conjugated diene monomer; x and z are, independently, a number equal to 0 or 1; and y is a whole number ranging from 1 to about 15. 
     
     
         5 . A lubricating oil composition according to  claim 1  wherein said block copolymer of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly (conjugated diene) is represented by the following formula:
   A-A/B—B   
       wherein: A is a polymeric block derived predominantly from vinyl aromatic hydrocarbon monomer; B is a polymeric block derived predominantly from conjugated diolefin monomer; and A/B is a tapered segment derived from both vinyl aromatic hydrocarbon monomer and conjugated diolefin monomer. 
     
     
         6 . A lubricating oil composition according to  claim 1  wherein said block copolymer of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly(conjugated diene) has a number average molecular weight ranging from 85,000 to 1,500,000. 
     
     
         7 . A lubricating oil composition according to  claim 1  wherein said block copolymer of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly(conjugated diene) has an SSI value of 2% to 50% after 90 cycles in the testing apparatus specified in the ASTM D6278-98 protocol with a diesel injector nozzle. 
     
     
         8 . A lubricating oil composition according to  claim 1  wherein said one or more optionally substituted bridged hydrocarbyl phenol condensates, or metal salts thereof are compounds represented by formula (I): 
       
         
           
           
               
               
           
         
       
       wherein d is 0 to 10; Y is a divalent hydrocarbyl or ether bridging group; each R is independently a hydrocarbyl group having from 4 to 30 carbon atoms, each b is independently 0, 1, 2 or 3, provided that at least one aromatic group has an R substituent and the total number of carbon atoms in all R groups is at least 7; each M is independently a an alkali or alkaline earth metal ion; each c is 0 or 1, provided that, when c is 0, M is replaced with H; and each X is independently H, —CHO or CH 2 OH. 
     
     
         9 . A lubricating oil composition according  claim 8  wherein said one or more optionally substituted bridged hydrocarbyl phenol condensates, or metal salts thereof are compounds represented by formula (II): 
       
         
           
           
               
               
           
         
       
       wherein d′ is 0 to 10; each Y′ is a divalent hydrocarbyl or ether bridging group; each R′ is independently a hydrocarbyl group having from 4 to 30 carbon atoms, provided that the total number of carbon atoms in all R′ groups is at least 7; each M′ is independently an alkali or alkaline earth metal ion; and each c′ is 0 or 1, provided that, when c′ is 0, M′ is replaced with H. 
     
     
         10 . A lubricating oil composition according  claim 8  wherein said one or more optionally substituted bridged hydrocarbyl phenol condensates, or metal salts thereof are compounds represented by formula (III): 
       
         
           
           
               
               
           
         
       
       wherein each X″ is independently —CHO or —CH 2 OH; each Y″ is a divalent hydrocarbyl or ether bridging group; provided that —CHO groups comprise at least about 10 mole percent of the X″ and Y″ groups; each M″ is independently an alkali or alkaline earth metal ion; each R″ is independently a hydrocarbyl group containing 1 to about 60 carbon atoms; d″ is 1 to about 10; c″ is 0 or 1 provided that when c″ is 0 the M″ is replaced with H; and each b″ is independently 0, 1, 2, or 3; provided that at least one aromatic ring contains an R″ substituent and the total number of carbon atoms in all R″ groups is at least 7; and further provided that if d″ is 1 or greater, then one of the X″ groups can be —H. 
     
     
         11 . A lubricating oil composition according  claim 1  wherein said one or more optionally substituted bridged hydrocarbyl phenol condensates, or metal salts thereof are optionally substituted bridged phenol/salicylate condensates, comprising one or more units of formula (IV) and/or formula (V): 
       
         
           
           
               
               
           
         
       
       each end of the compound having a terminal group which is independently a unit of formula (VI) or formula (VII): 
       
         
           
           
               
               
           
         
       
       with the proviso that said condensate must have at least one unit of formula (IV) or formula (VI) and one unit of either formula (V) or formula (VII); wherein in formulae (IV) through (VII), Y′″ is a divalent hydrocarbyl or ether bridging group R 1  is hydrogen or a hydrocarbyl group; R 2  is hydrogen or a hydrocarbyl group; e is 1 or 2; R 3  is hydrogen, a hydrocarbyl group or a hetero-substituted hydrocarbyl group; either R 1  is hydroxyl and R 2  and R 4  are independently either hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl, or R 2  and R 4  are hydroxyl and R 1  is either hydrogen, a hydrocarbyl group or a hetero-substituted hydrocarbyl group; with the proviso that Y′″ may optionally be sulfur in up to 50% of the units, such that the amount of sulfur incorporated in the molecule is up to 50 mole % of the Y groups; or metal salts of said condensates 
     
     
         12 . A lubricating oil composition according to  claim 1  comprising from about 0.5 to about 30 mass %, based on the total mass of the lubricating oil composition, of said optionally substituted bridged hydrocarbyl phenol condensates, or metal salts thereof, and from about 0.01 to about 10 mass %, based on the total mass of the lubricating oil composition, of said one or more block copolymers of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly(conjugated diene). 
     
     
         13 . A lubricating oil composition according to  claim 1  comprising one or more additional additives selected from the group consisting of dispersants, supplemental metallic detergents, supplemental viscosity modifiers, oxidation inhibitors, friction modifiers, antifoamants, antiwear agents and pour point depressants. 
     
     
         14 . A method of reducing soot-induced viscosity increase in engines, which method comprises the step lubricating a crankcase of the engine with a lubricating oil composition according to  claim 1 , and operating the engine.