Friction modifier composition for lubricants
View Patent ↗Combining a metal based friction modifier, such as a molybdenum dialkyldithiocarbamate, and certain esters of hydroxy carboxylic acids, such as short chain alkyl esters of citric or tartaric acid, e.g., tributyl citrate, has a synergistic effect on lowering the friction coefficient of lubricating oils allowing one to reduce the amount of metal based friction modifier needed to adequately formulate a lubricant with low friction characteristics.
1. A lubricant composition comprising:
A) 70 wt % or more of a synthetic poly alphaolefin lubricating oil, and
B) from about 0.5 to about 1.5 wt %, based on the weight of the lubricant composition, of a mixture of
i) a metal based friction modifier selected from the group consisting of molybdenum dialkyldithiocarbamates, and
ii) a hydroxy carboxylic ester
selected from the group consisting of triethyl citrate, tripropyl citrate and tributyl citrate;
wherein i) and ii) are present in a weight ratio of metal based friction modifier i) to hydroxy carboxylic ester ii) of about 1:1 based on the total weight of metal based friction modifier i) and hydroxy carboxylic ester ii).
2. The lubricant composition according to claim 1 further comprising one or more additional lubricant additive (C) selected from the group consisting of dispersants, detergents, corrosion/rust inhibitors, antioxidants, anti-wear agents, anti-foamants, friction modifiers, seal swell agents, demulsifiers, V.I improvers and pour point depressants.
3. The lubricant composition according to claim 1 wherein the synthetic poly alphaolefin lubricating oil is present from about 90 to about 99.5 wt %.
4. The lubricant composition according to claim 2 wherein the synthetic poly alphaolefin lubricating oil is present from about 95 to about 99 wt % and the combined amount of B) and C) is from about 1 to about 5 weight percent based on the total weight of the lubricant composition.