新型无硫无磷醚-酯化合物的合成及其作为无灰摩擦改进剂的性能研究

Synthesis of New Sulfur-free and Phosphorus-free Ether-ester and Study on Its Properties As Ashless Friction Modifier

伴随机械设备的升级换代和“双碳”政策的推行实施,长换油周期、清洁环保的高品质润滑油需求与日俱增,而新型添加剂和基础油以及二者之间配伍规律的研究始终贯穿于高性能润滑油的研发.摩擦改进剂作为提升低粘化油品耐久性润滑保护及燃油经济性至关重要的一类添加剂,其结构的设计与开发是润滑技术发展的前沿问题.为此,本工作设计并合成了新型无硫无磷醚-酯化合物DOA-mPEG350,通过核磁(NMR)、高分辨质谱(HR-MS)、红外(FT-IR)和凝胶色谱(GPC)表征了其结构,同时采用热重(TGA)和紫外分光光度法(UV-Vis)分析了DOA-mPEG350的热稳定性、以及其与合成烃基础油的相容性,利用四球摩擦磨损试验机系统研究了DOA-mPEG350作为无灰摩擦改进剂在合成烃基础油中的摩擦学行为.结果表明, DOA-mPEG350具有良好的热稳定性以及与合成烃基础油的相容性,其作为摩擦改进剂应用时能有效缩短跑合期, 1.0%(w)加剂量即可使合成烃CTL6基础油和PAO6基础油的平均摩擦系数、磨斑直径分别下降20.6%、20.1%和28.9%、34.8%,综合性能优于所选市售添加剂.通过摩擦表面分析及密度泛函理论(DFT)计算,揭示了醚-酯化合物的微观润滑机理,即通过醚链的“线接触”和酯基的“点接触”协同在金属表面形成有厚度且致密的保护膜,故表现出比仅含醚链或酯基结构化合物更优的摩擦学性能.

With the upgrading of mechanical equipment and the implementation of the“double-carbon”policy,the demand for high-quality lubricants with longer drain period,more clean and environmental friendly is increasing day by day.The study on new additives and base oils,as well as the compatibility law between the two has always run through the development of high-performance lubricants.As an important additive to improve the durability of lubricating protection and fuel economy,the design and development of friction modifier is the forefront of the development of lubrication technologies.Based on these,a new sulfur-free and phosphorus-free ether-ester DOA-mPEG350 was designed and synthesized,and characterized by nuclear magnetic resonance(NMR),high resolution mass spectrometer(HR-MS),Fourier transform infrared(FT-IR)and gel permeation chromatography(GPC).Meanwhile,the thermal stability of DOA-mPEG350 and its compatibility with synthetic hydrocarbon base oil were analyzed by thermogravimetric analysis(TGA)and ultraviolet visible spectroscopy(UV-Vis).The tribological behaviors of DOA-mPEG350 as an ashless friction modifier in synthetic hydrocarbons were studied using a four-ball friction and wear tester.The results show that DOA-mPEG350 has good thermal stability and compatibility with synthetic hydrocarbon base oil,and can effectively shorten the running-in period,and 1.0%(w)addition of DOA-mPEG350 could decrease the ave.coefficient of friction(COF)and wear scar diameter(WSD)of synthetic hydrocar-bons such as CTL6 and PAO6 base oils by 20.6%,20.1%and 28.9%,34.8%,respectively.The comprehensive friction reducing and anti-wear performance of DOA-mPEG350 is better than that of the selected commercial friction modifier and extreme pressure anti-wear additives,which are usually contain sulfur,phosphorus,or metals that can not meet the increasingly stringent environmental requirements,that is,the synthesized DOA-mPEG350 has the potential to replace these additives.Through analyzing the worn friction surface and density functional theory(DFT)calculation,the micro-lubrication mechanism of ether-ester is revealed,namely,it can combine the“line contact”of ether with the“point contact”of ester to form a thick and dense protective film on metal surfaces,thus showing better tribological performance than that only contain ether chain or ester group.