Comparison of Azelaic Acid and Sebacic Acidin Lithium Complex Grease

Fundamentals of Lithium-Based Grease

Lithium-based grease is a lubricantthickened with lithium soap and fortified with various performance-enhancingadditives. It exhibits excellent high-temperature stability and is widely usedin industries such as automotive, steel, railway, and aerospace. In recentyears, the demand for lithium complex grease has been rising, especially inEurope and the U.S., where azelaic acid-based lithium complex grease is favoredfor its superior anti-shear performance, fretting resistance, andhigh-temperature stability.

Application of Azelaic Acid and SebacicAcid in Lithium Complex Grease

Lithium complex grease is primarilythickened using a combination of lithium soap and low-molecular-weight lithiumsalts (such as diacids or triacids). While the Chinese market has traditionallyused a 12-hydroxystearic acid-sebacic acid system, the European and U.S.markets prefer a 12-hydroxystearic acid-azelaic acid system. Azelaicacid, with a melting point of 106°C, reacts more efficiently at 130°C comparedto sebacic acid, which has a higher melting point of 134°C. This leads to amore efficient synthesis process and enhances the grease’s overall performance.

Process Advantages of Azelaic Acid inLithium Complex Grease Production

Studies show that the azelaic acid-basedgrease exhibits high adaptability during production, allowing for a one-stepsynthesis process that simplifies manufacturing and improves efficiency.Additionally, azelaic acid-based grease demonstrates superior thermalstability, consistency retention, and anti-shear properties, making it suitablefor extreme operating conditions.

Technical Comparison of Azelaic Acid andSebacic Acid Grease Production

1. Saponification Time Has Minimal Impact on Performance
        Experiments indicate that varying the saponification time does not     significantly affect the final properties of the grease, demonstrating the     process stability of the azelaic acid system.

2. Complexing Time Affects Grease Stability
        A complexing reaction of at least 1 hour is necessary to ensure     proper grease consistency and high-temperature stability. Shorter reaction     times can lead to reduced heat resistance and lower shear stability.

3. Complexing Temperature Determines Final Performance
        The optimal complexing temperature for azelaic acid-based lithium complex     grease is 130-150°C. If the temperature is too low, the complexing     reaction remains incomplete, negatively impacting the grease’s heat     resistance and shear strength.

4. Cooling Method Affects Grease Structure
        Using a quenching (rapid cooling) process refines the grease’s crystalline     structure, enhancing its thermal stability and ensuring long-term     high-temperature lubrication.

Market Trends in the Use of Azelaic Acidand Sebacic Acid

The European and U.S. markets favor azelaicacid-based lithium complex grease due to its outstanding high-temperatureperformance. However, in China, azelaic acid is less commonly used due to itslimited domestic supply and higher production costs. Sebacic acid remains thepreferred option due to its lower cost.

As environmental regulations tighten andsebacic acid production faces restrictions, the rising price of its key rawmaterial, castor oil, has eroded its cost advantage. Under comparablecost conditions, azelaic acid-based lithium complex grease provides superiorperformance, making it an increasingly attractive alternative in the industry.