Lubricant compositions

Abstract

A lubricant composition comprises: (A) a non-silicone base stock oil; and (B) a silicone oil. The Viscosity Index of the lubricant composition, as measured in accordance with ASTM D 2270-10e1, is greater than that of the non-silicone lubricant base stock oil (A) by at least 10% and is shear stable according to DIN 51350-6.

Description

[0001]This application claims priority to and all the advantages of U.S. Provisional Patent Application No. 61 / 628,871, filed on Aug. 14, 2013, the content of which is incorporated herein by reference.TECHNICAL FIELD[0002]Disclosed herein are lubricant compositions comprising a non silicone lubricant base stock and a silicone oil.BACKGROUND[0003]Lubricant oils and compositions are used to reduce friction and wear between moving elements or surfaces. The main component of lubricant oils and compositions is commonly referred to as a base stock. Base stocks are classified by the American Petroleum Institute in five Groups, namely Groups I, II, III, IV and V. Lubricant base stocks include natural lubricating oils, synthetic lubricating oils, and mixtures thereof. Groups I to III include base stocks derived from petroleum based oils, while Groups IV and V include synthetic base stocks including silicones.[0004]The viscosity of a lubricant changes with temperature. As temperature rises vi...

AI Technical Summary

Benefits of technology

[0023]There is a need for lubricant compositions with a Viscosity Index (VI) of above 150, alternatively above 200, and good metal-to-metal lubrication, at acceptable cost. Currently Viscosity Index values of lubricant compositions are increased through the addition of additives typically referred to as viscosity index Improvers (VI Improvers). VI Improvers are currently typically high molecular weight organic polymers but their use does not always increase the Viscosity Index to the desired values for the purpose concerned and due to their high molecular weight said VI Improvers often lack shear stability. VI improvers are selected because they generally swell with increasing temperature which tends to counteract the decreasing viscosity of a base fluid as said temperature increases. This results in a lubricant that maintains sufficient oil thickness for lubrication at high temperatures. Conversely the VI improvers tend to shrink as temperatures decrease. In such situations the properties of the base oil dominate the viscosity of the fluid. However, VI Improvers are subject to shearing forces when present in lubricating situations and their stability as a result of these shearing forces (Shear Stability) may reduce their effectiveness. Excessive permanent shear effectively reduces lubricating temperature range of a lubricant and as such it is advantageous for lubricants to contain shear stable VI improvers in order to maintain or maximize the functional temperature range in which the fluid will lubricate.

Problems solved by technology

VI Improvers are currently typically high molecular weight organic polymers but their use does not always increase the Viscosity Index to the desired values for the purpose concerned and due to their high molecular weight said VI Improvers often lack shear stability.

However, VI Improvers are subject to shearing forces when present in lubricating situations and their stability as a result of these shearing forces (Shear Stability) may reduce their effectiveness.

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