Lithium Complex Soap Grease Processing in Non-Polar Base Oils
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Solution Overview
Problem
Conventional processes for producing lithium complex soap lubricating greases face challenges in achieving high dropping points, especially when using non-polar base oils, due to the lack of complex soap associations, and require excessive lithium hydroxide, which may be hazardous and costly.
Innovation Solution
Saponifying dicarboxylic acids with lithium or calcium hydroxide in a solid form in an aqueous environment, followed by reaction with hydroxy fatty acids and additional metal hydroxides, allowing for the formation of lithium or calcium complex soaps in an oleophilic base oil, thereby enhancing dropping points and reducing raw material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If saponification is carried out directly in base oil, then the process is simpler, but the dropping point remains low due to lack of complex soap associations
Solution Approach 1:
The saponification process is divided into two separate stages: first saponifying dicarboxylic acid with metal hydroxide in aqueous medium to form metal salt, then reacting this salt with hydroxy fatty acid in base oil to form complex soap. This segmentation allows formation of the desired complex soap structure that achieves high dropping points while maintaining process feasibility.
Solution Approach 2:
The dicarboxylic acid is saponified in advance in an aqueous environment to form the metal salt before introducing it to the base oil system. This preliminary action ensures that the complex soap associations can form properly in the base oil, achieving the required dropping point without compromising process simplicity.
2Reliability
If excessive lithium hydroxide is used to ensure complete saponification, then the reaction completeness improves, but safety and cost worsen
Solution Approach 1:
The metal salt of dicarboxylic acid serves as an intermediary that facilitates complete saponification of hydroxy fatty acid with stoichiometric amounts of lithium hydroxide. This intermediary approach ensures reaction completeness while avoiding the need for excessive lithium hydroxide, thereby improving safety and reducing costs.
Solution Approach 2:
The process changes the form of metal hydroxide from aqueous solution to solid form, and introduces the metal salt of dicarboxylic acid as an intermediate compound. This parameter change allows for more precise control of lithium hydroxide dosage, ensuring complete reaction without excess, thus improving safety and cost-effectiveness.
3Stability of the object's composition
If non-polar base oils are used, then the grease has good stability, but the dropping point decreases due to lack of complex soap formation
Solution Approach 1:
The process introduces a two-stage approach with intermediate metal salt formation, which enables complex soap structure formation even in non-polar base oils. This parameter change in the reaction pathway allows maintaining grease stability while achieving high dropping points through proper complex soap associations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process achieves high dropping points above 260°C for lithium complex soap greases and 190°C for calcium-lithium complex soap greases, improving thickener yield, mechanical stability, and reducing lithium hydroxide usage, while being more energy-efficient and safer.
Implementation Method 1
Saponifying dicarboxylic acids with lithium or calcium hydroxide in a solid form in an aqueous environment
Implementation Method 2
bringing into contact with one or more liquid or liquefied by heating hydroxy fatty acids and dissolving the metal salt(s) in the liquid hydroxy fatty acid
Implementation Method 3
adding further metal hydroxides, wherein according to alternative: (A1) lithium hydroxide or calcium hydroxide; (A2) lithium hydroxide and calcium hydroxide or only lithium hydroxide or only calcium hydroxide; or (A3) lithium hydroxide is added; for saponification with the at least one hydroxy fatty acid
Implementation Method 4
driving off water with heating
Data Source
AI summary
The invention relates to a method for producing lubricating greases of lithium complex soaps or lithium-calcium complex soaps, to corresponding lubricating greases produced according to said method and to the use thereof in sliding and rolling bearings.