Lubricant composition comprising hydroxycarboxylic acid derived friction modifier
The present invention relates to a lubricant composition containing a base stock and at least 0.01 wt % of a friction reducing additive which is a compound of the Formula (I): R 1 [(AO) n —R 2 ] m (I) wherein R 1 is the residue of a group having at least 2 active hydrogen atoms; m is at least 2; AO is an alkylene oxide residue; each n is independently from 0 to 100; and each R 2 is independently H or R 3 , where each R 3 is independently a residue of a polyhydroxyalkyl or polyhydroxyalkenyl carboxylic acid, a residue of a hydroxyalkyl or hydroxyalkenyl carboxylic acid and/or a residue of an oligomer of the hydroxyalkyl or hydroxyalkenyl carboxylic acid; and on average at least 0.5 of R 2 groups are R 3 . The lubricant composition is suitable for use in an engine oil, a hydraulic oil or fluid, a gear oil and/or a metal-working fluid.
1. A lubricant composition comprising a base stock and at least 0.10 wt % of a friction reducing additive which comprises a compound of Formula (I):
R 1 [(AO) n —R 2 ] m (I)
wherein:
R 1 is a residue of a monosaccharide or a disaccharide;
m is 4 to 10;
AO is an alkylene oxide residue, where A is —(C r H 2r O)— and r is 2, 3 or 4;
each n is independently from 2 to 20;
each R 2 is independently H or R 3 , where each R 3 is independently a residue of a polyhydroxyalkyl or polyhydroxyalkenyl carboxylic acid, a residue of a hydroxyalkyl or hydroxyalkenyl carboxylic acid and/or a residue of an oligomer of the hydroxyalkyl or hydroxyalkenyl carboxylic acid; and
on average at least 0.5 of R 2 groups are R 3 ,
wherein the lubricant composition is non-aqueous,
wherein the product of indices n×m is 10 to 100, and
wherein the friction reducing additive has a molecular weight (Mn) between 3,000 to 10,000, and is capable of reducing a coefficient of friction of the lubricant composition by at least 20% when measured using a mini-traction machine (MTM).
2. The lubricant composition according to claim 1 wherein R 1 is a residue of a monosaccharide selected from the group consisting of glucose, fructose and sorbitol or a residue of a disaccharide selected from the group consisting of maltose, palitose, lactitol and lactose.
3. The lubricant composition according to claim 1 wherein m is 5 to 6.
4. The lubricant composition according to claim 1 wherein n×m is 25 to 100.
5. The lubricant composition according to claim 1 wherein at least 2.0 of the R 2 groups are R 3 .
6. The lubricant composition according to claim 1 wherein R 3 is a residue of a polyhydroxyalkyl carboxylic acid.
7. The lubricant composition according to claim 6 wherein the number of hydroxyalkyl monomers in the polyhydroxyalkyl carboxylic acid residue is 3 to 10.
8. The lubricant composition according to claim 1 wherein at least 2.0 of the R 2 groups are H.
9. The lubricant composition according to claim 1 wherein the friction reducing additive is an ethoxylated sorbitol ester of a polyhydroxyalkyl carboxylic acid.
10. The lubricant composition according to claim 1 wherein the base stock is selected from the group consisting of an API Group I, II, III, IV, V base oil or mixtures thereof.
11. The lubricant composition according to claim 1 wherein the lubricant composition is a gear oil.
12. The lubricant composition according to claim 1 wherein the lubricant composition is an engine oil.
13. An engine comprising the lubricant composition according to claim 12 .
14. A method of reducing friction in an automotive engine which comprises using an engine oil comprising a base stock and at least 0.01 wt % of a friction reducing additive which comprises a compound of the Formula (I):
R 1 [(AO) n —R 2 ] m (I)
wherein:
R 1 is a residue of a monosaccharide or a disaccharide;
m is 4 to 10;
AO is an alkylene oxide residue, where A is —(C r H 2r O)— and r is 2, 3 or 4;
each n is independently from 2 to 20; and
each R 2 is independently H or R 3 , where each R 3 is independently a residue of a polyhydroxyalkyl or polyhydroxyalkenyl carboxylic acid, a residue of a hydroxyalkyl or hydroxyalkenyl carboxylic acid and/or a residue of an oligomer of the hydroxyalkyl or hydroxyalkenyl carboxylic acid; and
on average at least 0.5 of R 2 groups are R 3 ,
wherein the engine oil is non-aqueous,
wherein the product of indices n×m, is 10 to 100, and
wherein the friction reducing additive has a molecular weight (Mn) between 3,000 to 10,000, and is capable of reducing a coefficient of friction of the lubricant composition by at least 20% when measured using a mini-traction machine (MTM).
15. The lubricant composition according to claim 1 wherein the residue of a polyhydroxyalkyl or polyhydroxyalkenyl carboxylic acid, the residue of a hydroxyalkyl or hydroxyalkenyl carboxylic acid and/or the residue of an oligomer of the hydroxyalkyl or hydroxyalkenyl carboxylic acid is derived from a hydroxyalkyl or hydroxyalkenyl carboxylic acid of formula HO—X—COOH where X is a divalent saturated or unsaturated aliphatic radical containing 8 to 20 carbon atoms.
16. The method according to claim 14 wherein the residue of a polyhydroxyalkyl or polyhydroxyalkenyl carboxylic acid, the residue of a hydroxyalkyl or hydroxyalkenyl carboxylic acid and/or the residue of an oligomer of the hydroxyalkyl or hydroxyalkenyl carboxylic acid is derived from a hydroxyalkyl or hydroxyalkenyl carboxylic acid of formula HO—X—COOH where X is a divalent saturated or unsaturated aliphatic radical containing 8 to 20 carbon atoms.
17. The lubricant composition according to claim 1 , where R 1 is a residue of a monosaccharide selected from the group consisting of glucose, fructose and sorbitol.
18. The method according to claim 14 , where R 1 is a residue of a monosaccharide selected from the group consisting of glucose, fructose and sorbitol.
19. The lubricant composition according to claim 1 , where r is 2.
20. The method according to claim 14 , where r is 2.