Lubricant Composition

Abstract

A lubricant composition is prepared having a base oil composition and an additive composition comprising a molybdenum dialkyldithiocarbamate and an organic friction modifier such as an oil-soluble mono-, di- or tri-glyceride of at least one hydroxyl polycarboxylic acid, or a derivative thereof may, especially when used in combination with a base oil composition of a functionally modified poly-alpha-olefin (e.g. alpha-olefin and ester copolymer), a poly-alpha-olefin and optionally an additive carrier such as an alkylated naphthalene. The lubricant composition of the present invention finds particular application as a lubricant composition for robotics and robotic gearboxes, industrial gears and wind turbine gears and especially for gearboxes having a rolling element (such as a spherical bearing or a cylindrical bearing). It provides enhanced longevity, good elastomer compatibility and good anti-wear properties. Embodiments of the invention also demonstrate excellent protection against leaks and sludge.

1 . A lubricant composition comprising: a base oil composition of lubricating viscosity; and an additive composition comprising a molybdenum dialkyldithiocarbamate and an oil-soluble mono-, di- or tri-glyceride of at least one hydroxyl polycarboxylic acid, or a derivative thereof. 
     
     
         2 . A lubricant composition as claimed in  claim 1 , wherein the molybdenum dialkyldithiocarbamate is provided in an amount, in terms of molybdenum, of from 500 to 3000 ppm of the lubricant composition. 
     
     
         3 . A lubricant composition as claimed in  claim 2 , wherein the molybdenum dialkyldithiocarbamate is provided in an amount, in terms of molybdenum, of from 750 to 1500 ppm of the lubricant composition. 
     
     
         4 . A lubricant composition as claimed in  claim 1 , wherein the oil-soluble mono-, di- or tri-glyceride of at least one hydroxyl polycarboxylic acid, or a derivative thereof is provided in an amount of 0.1 to 2.5% by weight of the lubricant composition. 
     
     
         5 . A lubricant composition as claimed in  claim 1 , wherein the oil-soluble mono-, di- or tri-glyceride of at least one hydroxyl polycarboxylic acid, or a derivative thereof is provided in a percent by weight ratio relative to the molybdenum dialkyldithiocarbamate in the range from 1:3 to 1:1. 
     
     
         6 . A lubricant composition as claimed in  claim 1 , which has no more than 0.1% molybdenum dithiophosphate. 
     
     
         7 . A lubricant composition as claimed in  claim 1 , which is absent molybdenum dithiophosphate. 
     
     
         8 . A lubricant composition as claimed in  claim 1 , wherein the additive composition further comprises a long chain fatty amide in an amount of up to 1% by weight of the lubricant composition. 
     
     
         9 . A lubricant composition as claimed in  claim 1 , wherein the additive composition makes up a proportion of the lubricant composition of up to 10% by weight. 
     
     
         10 . (canceled) 
     
     
         11 . A lubricant composition comprising: a base oil composition of lubricating viscosity; and an additive composition comprising a molybdenum dialkyldithiocarbamate and a metal-free organic friction modifier. 
     
     
         12 . (canceled) 
     
     
         13 . An additive composition comprising a molybdenum dialkyldithiocarbamate and an oil-soluble mono-, di- or tri-glyceride of at least one hydroxyl polycarboxylic acid, or a derivative thereof. 
     
     
         14 . A base oil composition comprising a functionally modified poly-alpha-olefin, a poly-alpha-olefin and optionally an additive carrier. 
     
     
         15 . A base oil composition as claimed in  claim 14 , wherein the modified poly-alpha olefin is a poly-alpha-olefin functionalised with as an ester group. 
     
     
         16 . (canceled) 
     
     
         17 . A base oil composition as claimed in  claim 15 , wherein the modified poly-alpha-olefin is a co-polymer of an alpha-olefin monomer with an olefinic alkyl ester with a decene olefin chain length and in a ratio of alpha olefin monomer and functionalised monomer in the range 3:2 to 5:1 
     
     
         18 - 20 . (canceled) 
     
     
         21 . A base oil composition as claimed in  claim 14 , wherein the poly-alpha-olefin and modified poly-alpha-olefin make up at least 75% by weight of the base oil composition. 
     
     
         22 . A base oil composition as claimed in  claim 14 , wherein the base oil composition comprises one or more additive carriers selected from alkylated naphthalene, alkyl benzene and low viscosity esters. 
     
     
         23 . A base oil composition as claimed in  claim 22 , wherein the additive carrier comprises alkylated naphthalene in an amount of up to 25% by weight of the base oil composition. 
     
     
         24 . A synthetic gear oil composition comprising: a base oil composition comprising a modified poly alpha olefin; and an additive composition comprising a molybdenum dialkyldithiocarbamate and an oil-soluble mono-, di- or tri-glyceride of at least one hydroxyl polycarboxylic acid, or a derivative thereof. 
     
     
         25 . (canceled) 
     
     
         26 . (canceled) 
     
     
         27 . A method of lubricating a gearbox comprising a rolling element, the method comprising supplying to the gearbox an oil of lubricating viscosity having the lubricating composition as defined in  claim 1 . 
     
     
         28 . A method of operating an apparatus having a gearbox comprising a rolling element, the method comprising supplying to the gearbox a lubricating oil of lubricating viscosity having a composition as defined in  claim 1 .