Lithium Grease Thickener System for Water Resistance and Shear Stability
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Solution Overview
Problem
Conventional lubricating greases face challenges in achieving improved water resistance, shear stability, reduced oil bleeding, and high dropping points, while also being limited by the scarcity of lithium, which is typically used in high quantities.
Innovation Solution
A lubricating grease composition comprising a base oil and a thickener system consisting of a lithium soap of C12 to C24 hydroxycarboxylic acid and an alkaline earth metal salt of C2 to C12 dicarboxylic acid, with a weight ratio between 20:1 to 1:1, which reduces lithium usage by 40-50% compared to conventional lithium complex-based greases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium complex-based grease compositions are used to achieve good lubrication properties, then lubrication performance is improved, but lithium consumption increases and becomes unsustainable
Solution Approach 1:
The patent changes the chemical composition parameters by replacing conventional lithium complex soap thickeners with a novel thickener system comprising lithium soap of hydroxycarboxylic acid combined with alkaline earth metal salt of dicarboxylic acid. This parameter change maintains lubrication performance while reducing lithium content by 40-50%, directly resolving the contradiction between reliability and lithium consumption.
Solution Approach 2:
The patent employs a composite thickener system combining two distinct components: lithium soap of C12-C24 hydroxycarboxylic acid and alkaline earth metal salt of C2-C12 dicarboxylic acid. This composite approach creates a synergistic effect that achieves comparable or superior lubrication properties to conventional lithium complex greases while significantly reducing lithium dependency.
2Reliability
If grease formulations are optimized for high dropping points and improved water resistance, then performance is improved, but shear stability and oil bleeding properties deteriorate
Solution Approach 1:
The patent uses a composite thickener system where lithium soap of hydroxycarboxylic acid provides high dropping point and water resistance, while alkaline earth metal salt of dicarboxylic acid contributes to shear stability and reduced oil bleeding. The synergistic interaction between these two components resolves the contradiction by achieving all four properties simultaneously.
Solution Approach 2:
The patent assigns different functional qualities to different thickener components: the lithium soap component primarily provides high dropping point and water resistance, while the alkaline earth metal salt component primarily provides shear stability and controls oil bleeding. This local quality differentiation allows the overall grease composition to achieve all desired properties without compromise.
Data Source
AI summary
Lubricating grease composition comprising: (i) a base oil; (ii) a thickener system comprising (a) a lithium soap of a C12 to C24 hydroxycarboxylic acid and (b) an alkaline earth metal salt of a C2 to C12 dicarboxylic acid. The lubricating grease compositions according to the present invention exhibit increased water resistance and shear stability together with excellent oil bleeding properties. The lubricating grease compositions of the present invention also contain lower levels of lithium than present in a conventional lithium based grease composition.