Lubricating Composition Containing a Dispersant

Abstract

The invention provides a lubricating composition containing a lubricating composition comprising an oil of lubricating viscosity and a quaternised polyester salt. The invention further relates to a method of lubricating a mechanical device (such as an internal combustion engine) with the lubricating composition. The invention further relates to the use of the quaternised polyester salt as a dispersant.

What is claimed is: 
     
         1 . A lubricating composition comprising an oil of lubricating viscosity
 0.1 wt % to 15 wt % of a dispersant, wherein the dispersant is a polyisobutylene succinimide, wherein the polyisobutylene from which the polyisobutylene succinimide is derived has a number average molecular weight in the range of 350 to 5000.   and 0.1 wt % to 10 wt % of a quaternised polyester salt which comprises a product obtained/obtainable by reaction of (i) a polyester containing a tertiary amino group; and (ii) a quaternising agent suitable for converting the tertiary amino group to a quaternary nitrogen, wherein the quaternising agent is selected from the group consisting of a dialkyl sulphate, a benzyl halide, an organic carbonate, an ester of a polycarboxylic acid, an organic epoxide in combination with an acid, and mixtures thereof.   
     
     
         2 . The lubricating composition of  claim 1  wherein the polyester comprises the reaction product of a fatty carboxylic acid containing at least one hydroxyl group and a compound having an oxygen or nitrogen atom capable of condensing with said acid and further having a tertiary amino group. 
     
     
         3 . The lubricating composition of  claim 2  wherein the fatty carboxylic acid is represented by the formula: 
       
         
           
           
               
               
           
         
         where R 1  is a hydrogen or a hydrocarbyl group containing from 1 to 20 carbon atoms and R 2  is a hydrocarbylene group containing from 1 to 20 carbon atoms, with the proviso that the total number of carbon atoms present from R 1  and R 2  is 6 or more, or 8 or more; and
 wherein the compound having an oxygen or nitrogen atom capable of condensing with said acid and further having a tertiary amino group is represented by the formula: 
 
       
       
         
           
           
               
               
           
         
         where R 3  is a hydrocarbyl group containing from 1 to 10 carbon atoms; R 4  is a hydrocarbyl group containing from 1 to 10 carbon atoms; R 5  is a hydrocarbylene group containing from 1 to 20 carbon atoms; and X 1  is O or NR 6  where R 6  is a hydrogen or a hydrocarbyl group containing from 1 to 10 carbon atoms. 
       
     
     
         4 - 15 . (canceled) 
     
     
         16 . The lubricating composition of  claim 1 , wherein the quaternised polyester salt comprises a quaternised polyester amide salt wherein the polyester containing a tertiary amino group used to prepare said quaternised polyester salt comprises a polyester amide containing a tertiary amino group. 
     
     
         17 . The lubricating composition of  claim 1 , wherein the quaternised polyester salt comprises a cation represented by the following formula: 
       
         
           
           
               
               
           
         
         where R 1  is a hydrogen or a hydrocarbyl group containing from 1 to 20 carbon atoms and R 2  is a hydrocarbylene group containing from 1 to 20 carbon atoms; R 3  is a hydrocarbyl group containing from 1 to 10 carbon atoms; R 4  is a hydrocarbyl group containing from 1 to 10 carbon atoms; R 5  is a hydrocarbylene group containing from 1 to 20 carbon atoms; R 6  is a hydrogen or a hydrocarbyl group containing from 1 to 10 carbon atoms; n is a number from 1 to 10; R 7  is hydrogen, a hydrocarbyl-substituted carbonyl group containing from 1 to 22 carbon atoms, or a hydrocarbyl group containing from 1 to 22 carbon atoms; and X 2  is a group derived from the quaternising agent. 
       
     
     
         18 . The lubricating composition of  claim 2 , wherein the compound having an oxygen or nitrogen atom capable of condensing with said acid and further having a tertiary amino group comprises N,N-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-dibutylethylenediamine, N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane, N,N-dimethylamino ethanol, N,N-diethylaminoethanol, or combinations thereof. 
     
     
         19 . The lubricating composition of  claim 2 , wherein the fatty carboxylic acid containing at least one hydroxyl group comprises: 12-hydroxystearic acid; ricinoleic acid; 12-hydroxy dodecanoic acid; 5-hydroxy dodecanoic acid; 5-hydroxy decanoic acid; 4-hydroxy decanoic acid; 10-hydroxy undecanoic acid; or combinations thereof. 
     
     
         20 . The lubricating composition of  claim 1 , wherein the quaternising agent comprises ethylene oxide, propylene oxide, butylene oxide, styrene oxide, or combinations thereof in combination with an acid. 
     
     
         21 . The lubricating composition of  claim 1 , wherein the quaternised polyester salt is present at 1 wt % to 8 wt % of the lubricating composition. 
     
     
         22 . The lubricating composition of  claim 1 , wherein the quaternised polyester salt is present at 2 wt % to 6.5 wt % of the lubricating composition. 
     
     
         23 . The lubricating composition of  claim 1 , wherein the polyisobutylene from which the polyisobutylene succinimide is derived has a number average molecular weight in the range of 750 to 2200. 
     
     
         24 . The lubricating composition of  claim 1 , wherein the dispersant is a polyisobutylene succinimide derived from an aliphatic polyamine selected from ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyamine still bottoms, and mixtures thereof. 
     
     
         25 . The lubricating composition of  claim 23 , wherein the dispersant is present at 0.5 wt % to 9 wt % of the lubricating composition. 
     
     
         26 . The lubricating composition of  claim 23 , wherein the dispersant is present at 1 wt % to 8.5 wt % of the lubricating composition. 
     
     
         27 . A method of lubricating an internal combustion engine comprising supplying to the internal combustion engine a lubricating composition of  claim 1 . 
     
     
         28 . The method of  claim 27 , wherein the internal combustion engine has a steel surface on a cylinder bore, cylinder block, or piston ring. 
     
     
         29 . The method of  claim 27 , wherein the internal combustion engine has a surface of steel, or an aluminium alloy, or an aluminium composite.