Lubricant composition comprising traction coefficient additive

1 . A lubricant composition, suitable for use in an electric vehicle, comprising at least 50 wt % of a base stock based on the total weight of the lubricant composition and at least 7 wt % of a traction coefficient additive compound, based on the total weight of the lubricant composition, wherein the traction coefficient additive is present in an amount effective to provide a reduced traction coefficient and wherein the traction coefficient additive is 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 ; and

wherein the lubricant composition is in contact with the power train of the electric vehicle in a manner effective to reduce the traction coefficient in a gear box of the powertrain.

2 . A lubricant composition in accordance with claim 1 , wherein R 1 of the traction coefficient additive compound of the Formula (I) is the residue of a C 3 to C 30 substituted hydrocarbyl compound.

3 . A lubricant composition in accordance with claim 2 , wherein R 1 of the traction coefficient additive compound of the Formula (I) is the residue of, or a residue derived from, a sugar.

4 . A lubricant composition in accordance with claim 3 , wherein R 1 of the traction coefficient additive compound of the Formula (I) is the residue of, or a residue derived from glucose, fructose, or sorbitol.

5 . A lubricant composition in accordance with claim 4 , wherein m of the traction coefficient additive compound of the Formula (I) is at least 3.

6 . A lubricant composition in accordance with claim 5 , wherein m of the traction coefficient additive compound of the Formula (I) is in the range from 4 to 10.

7 . A lubricant composition in accordance with claim 6 , wherein the alkylene oxide groups AO of the traction coefficient additive compound of the Formula (I) are of the formula:

—(C r H 2r O)—

where r is 2, 3 or 4.

8 . A lubricant composition in accordance with claim 7 , wherein n of the traction coefficient additive compound of the Formula (I) is in the range from 1 to 50.

9 . A lubricant composition in accordance with claim 8 , wherein each R 3 of the traction coefficient additive compound of the Formula (I) is a residue of a polyhydroxylalkyl or polyhydroxyalkenyl carboxylic acid of formula HO—X—COOH where X is a divalent saturated or unsaturated, preferably saturated, aliphatic radical containing at least 8 carbon atoms and no more than 20 carbon atoms.

10 . A lubricant composition in accordance with claim 9 , wherein each R 3 of the traction coefficient additive compound of the Formula (I) is (poly) 12-hydroxystearic acid.

11 . A lubricant composition in accordance with claim 1 , comprising up to 20 wt % of the traction coefficient additive, based on the total weight of the lubricant composition.

12 . A lubricant composition in accordance with claim 1 , wherein the lubricant composition is a gearbox oil, comprising 7 wt % to 20 wt % of the traction coefficient additive, based on the total weight of the gearbox oil.

13 . A method of reducing traction coefficient in a gearbox of an electric vehicle which comprises using a lubricant composition of claim 1 in the gearbox.

14 . The lubricant composition of claim 3 , wherein the sugar is a monosaccharide.