Lubricating composition comprising poly(hydroxycarboxylic acid) amide and detergent

Abstract

The present invention provides a lubricating composition comprising: a base oil; one or more poly (hydroxycarboxylic acid) amide salt derivatives having Formula (III): [Y—CO [O-A-CO] n —Z—R + ]m pX q− wherein Y is hydrogen or an optionally substituted hydrocarbyl group, A is a divalent optionally substituted hydrocarbyl group, n is from 1 to 100, preferably from 1 to 10, m is from 1 to 4, q is from 1 to 4 and p is an integer such that pq=m, Z is an optionally substituted divalent bridging group which is attached to the carbonyl group through a nitrogen atom, R + is an ammonium group and X q− is an anion; and one or more detergents; wherein the soap concentration as provided by a detergent selected from the group of sulphonate and salicylate detergents is less than 3.75 mmol soap per wt. % of the one or more poly (hydroxycarboxylic acid) amide salt derivatives having Formula (III).

1 . A lubricating composition comprising:
 a base oil;   one or more poly(hydroxycarboxylic acid) amide salt derivatives having formula (III):
   [Y—CO[O-A-CO] n —Z—R + ] m   p X q−   (III)
 
   
       wherein Y is hydrogen or an optionally substituted hydrocarbyl group, A is a divalent optionally substituted hydrocarbyl group, n is from 1 to 100, preferably from 1 to 10, m is from 1 to 4, q is from 1 to 4 and p is an integer such that pq=m, Z is an optionally substituted divalent bridging group which is attached to the carbonyl group through a nitrogen atom, R +  is an ammonium group and X q−  is an anion; and
 one or more detergents; 
 wherein the soap concentration as provided by a detergent selected from the group of sulphonate and salicylate detergents or a mixture thereof is less than 3.75 mmol soap per wt. % of the one or more poly(hydroxycarboxylic acid) amide salt derivatives having formula (III), preferably less than 3.0 mmol soap, more preferably less than 2.5 mmol soap, even more preferably less than 2.0 mmol soap, most preferably less than 1.0 mmol soap. 
 
     
     
         2 . The lubricating composition according to  claim 1 , wherein the one or more detergents comprise no detergent selected from the group of sulphonate and salicylate detergents. 
     
     
         3 . The lubricating composition according to  claim 1  wherein the one or more detergents consist of one or more phenate detergents. 
     
     
         4 . The lubricating composition according to  claim 1  wherein one or more of the poly(hydroxycarboxylic acid) amide salt derivatives have a TBN (total base number) value of less than 10 mg·KOH/g. 
     
     
         5 . The lubricating composition according to  claim 1 , wherein the composition comprises less than 2.5 wt. %, preferably less than 2.0 wt. %, more preferably less than 1.5 wt. %, even more preferably less than 1.2 wt. % of the one or more poly(hydroxycarboxylic acid) amide salt derivatives having formula (III), based on the total weight of the lubricant composition. 
     
     
         6 . (canceled)