Lubricant composition

Abstract

A lubricant composition is suitable for use in diesel engines and is resistant to degradation by oxidative by-products of biodiesel fuel. The composition includes (A) a base oil, (B) at least one diphenylamine antioxidant, and (C) at least one antioxidant. The antioxidant (C) is selected from the group consisting of a sulfur containing phenolic antioxidant, a phenyl-alpha-naphthylamine antioxidant, and combinations thereof. The lubricant composition is formed using a method. In the method, the (A) base oil has an initial oxidation value measured according to ASTM D 6186. In addition in the method, the lubricant composition includes up to about 6 wt % of the biodiesel fuel and has a final oxidation value measured according to ASTM D 6186 that is equal to or greater than the initial oxidation value of the (A) base oil.

Description

RELATED APPLICATIONS[0001]This application claims priority to U.S. Prov. Ser. No. 61 / 231,468, filed on Aug. 5, 2009, the disclosure of which is expressly incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention generally relates to a lubricant composition including a base oil and two antioxidants. More specifically, the lubricant composition includes the base oil, at least one diphenylamine antioxidant, and at least one sulfur containing phenolic antioxidant and / or phenyl-alpha-naphthylamine antioxidant.DESCRIPTION OF THE RELATED ART[0003]Lubricant compositions are generally well known in the art and are broadly categorized as oil or water based compositions, i.e., compositions that include large weight percentages of non-polar compounds or large weight percentages of water. Lubricant compositions are typically further categorized as engine oils, driveline system oils, gear oils, automatic and manual transmission fluids and oils, hydraulic o...

AI Technical Summary

Benefits of technology

[0024]The instant invention provides a lubricant composition that is suitable for use as in diesel engines and that is resistant to degradation by oxidative by-products of biodiesel fuel. The lubricant composition includes (A) a base oil, (B) at least one diphenylamine antioxidant, and (C) at least one antioxidant selected from the group consisting of a sulfur containing phenolic antioxidant, a phenyl-alpha-naphthylamine antioxidant, and combinations thereof. The invention also provides a method for improving the performance of the lubricant composition by improving resistance to degradation by oxidative by-products of the biodiesel fuel. The method includes the steps of providing the (A) base oil, providing the (B) at least one diphenylamine antioxidant, and providing the (C) at least one antioxidant. The method also includes the step of combining (A), (B), and (C) to form the lubricant composition. In the method, the (A) base oil has an initial oxidation value measured according to ASTM D 6186. In addition in the method, the lubricant composition includes up to about 6 wt % of the biodiesel fuel and has a final oxidation value measured according to ASTM D 6186 that is equal to or greater than the initial oxidation value of the (A) base oil. The antioxidants (B) and (C) supplement the (A) base oil and overall lubricant composition and allow the lubricant composition to resist degradation by oxidative by-products of biodiesel fuel.

Problems solved by technology

Biodiesel fuel derived from vegetable oil tends to include unsaturated alkyl groups which are more prone to oxidation than saturated alkyl groups.

These oxidative by-products directly affect the performance of the lubricant compositions that flow through the sumps.

Even though many lubricant compositions include antioxidants, these antioxidants are traditionally insufficient and ineffective in neutralizing the oxidative by-products of the biodiesel fuels.

As a result, performance and durability of the lubricant compositions and the diesel engines, suffer.

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