Multi-Dispersant Lubricating Composition

Abstract

The present invention relates to a lubricating composition containing a corrosion inhibitor compound and a mixture of two or more dispersants, wherein 0 mole % to less than 50 mole % of the second dispersant molecules contain a carbocyclic ring. The invention further provides a method for lubricating a mechanical device using the lubricating composition.

1 .- 29 . (canceled) 
   
   
       30 . A lubricating composition comprising:
 (a) an oil of lubricating viscosity;   (b) a first dispersant comprising a product prepared by heating together:
 (i) a first dispersant substrate; 
 (ii) a thiadiazole compound; 
 (iii) a borating agent; and 
 (iv) a dicarboxylic acid of an aromatic compound selected from the group consisting of 1,3 diacids and 1,4 diacids, and 
 (v) optionally a phosphorus acid compound, said heating being sufficient to provide a product of (i), (ii), (iii) and (iv) and optionally (v), which is soluble in an oil of lubricating viscosity; 
   (c) a second dispersant, wherein 0 mole % to less than 50 mole % of the second dispersant molecules contain a carbocyclic ring; and   (d) a corrosion inhibitor.   
   
   
       31 . The lubricating composition of  claim 30 , wherein the corrosion inhibitor comprises an oil soluble 2,5-dimercapto-1,3,4-thiadiazole, other than (b). 
   
   
       32 . The lubricating composition of  claim 31 , wherein the corrosion inhibitor is present in the range of 0.005 wt % to 5 wt % of the lubricating composition. 
   
   
       33 . The lubricating composition of  claim 30 , wherein the first dispersant is prepared by an “ene” reaction. 
   
   
       34 . The lubricating composition of  claim 30 , wherein the second dispersant is prepared from a succinic anhydride from an “ene” reaction. 
   
   
       35 . The lubricating composition of  claim 30 , wherein 0 mole % to less than 20 mole % of the second dispersant molecules contain a carbocyclic ring. 
   
   
       36 . The lubricating composition of  claim 30 , wherein the first dispersant and second dispersant both have a CO:N ratio of 2:1 to 1:10. 
   
   
       37 . The lubricating composition of  claim 30 , wherein the first dispersant is prepared in the presence of a dicarboxylic acid of an aromatic compound selected from the group consisting of 1,3 diacids and 1,4 diacids. 
   
   
       38 . The lubricating composition of  claim 37 , wherein the dicarboxylic acid of an aromatic compound comprises terephthalic acid. 
   
   
       39 . The lubricating composition of  claim 30 , wherein the oil of lubricating viscosity has a sulphur content in range of 0 ppm to 1000 ppm. 
   
   
       40 . The lubricating composition of  claim 30 , further comprising a friction stabilising agent, wherein the friction stabilising agent comprises H 3 PO 4 , H 3 PO 3  or mixtures thereof, and wherein the friction stabilising agent is present at 0.01 wt % to 0.5 wt % of the lubricating composition. 
   
   
       41 . The lubricating composition of  claim 30 , further comprising an antiwear agent selected from the group consisting of (i) a non-ionic phosphorus compound; (ii) an amine salt of a phosphorus compound; (iii) an ammonium salt of a phosphorus compound; (iv) a monovalent metal salt of a phosphorus compound, such as a metal dialkyldithiophosphate or a metal dialkylphosphate; and (v) mixtures of (i), (ii), (iii) or (iv). 
   
   
       42 . The lubricating composition of  claim 30 , further comprising an antioxidant, wherein the antioxidant comprises at least one of sulphurised olefins, hindered phenols, phenylalphanaphthylamines, alkylated diphenylamines, hydroxylalkyl sulphides, or mixtures thereof. 
   
   
       43 . The lubricating composition of  claim 42 , wherein the antioxidant is present at 0.01 wt % to 5 wt % of the lubricating composition. 
   
   
       44 . The lubricating composition of  claim 30 , further comprising a friction modifier. 
   
   
       45 . The lubricating composition of  claim 44 , wherein the friction modifier is present at 0.1 wt % to 4 wt %. 
   
   
       46 . The lubricating composition of  claim 30 , wherein the oil of lubricating viscosity has an aromatic content of 0 wt % to 10 wt %. 
   
   
       47 . The lubricating composition of  claim 30 , wherein the oil of lubricating viscosity has a viscosity index of 105 or more. 
   
   
       48 . A method of lubricating a mechanical device, comprising supplying the lubricating composition of  claim 30  to the mechanical device. 
   
   
       49 . The method of claim  27 , wherein the mechanical device comprises an automatic transmission. 
   
   
       50 . A lubricating composition comprising:
 (a) an oil of lubricating viscosity;   (b) a first dispersant comprising a product prepared by heating together:
 (i) a first dispersant substrate; 
 (ii) a thiadiazole compound; 
 (iii) a borating agent; and 
 (iv) optionally a dicarboxylic acid of an aromatic compound selected from the group consisting of 1,3 diacids and 1,4 diacids, and 
 (v) optionally a phosphorus acid compound, said heating being sufficient to provide a product of (i), (ii), (iii) and optionally (iv) and optionally (v), which is soluble in an oil of lubricating viscosity; 
   (c) a second dispersant, wherein 0 mole % to less than 50 mole % of the second dispersant molecules contain a carbocyclic ring; and   (d) an oil soluble dimercaptothiadiazole corrosion inhibitor, other than (b).