Multi-steps synthesis and properties of tetraurea grease

Lubricating grease consists of three principal ingredients, a base oil, a thickener, and additives ([1] Bessette, 2005), which is applied widely in our life ([2] Hamori et al. , 1998). As one of these products, the polyurea grease using organic urea thickener was discovered by [3] Swaken (1954). Because of its excellent performance, such as high-antioxidant stability, high-temperature performance, high stability ([4] Anthony and Achim, 2004), it has been applied widely in the steel, auto, mechanical industry, especially in the military industry, together with the development direction of lubricating grease in today world, as well as a important indicate for the grease industry of one country ([5] Borisenko, 2004).

Currently, existing research are focused on the synthesis and properties of diurea grease. [6] Nozaki et al. (2001) and [7] Akabe et al. (1998) used diisocyanate and monoamine to prepare the satisfactory durability and cost-effectiveness diurea grease. Otherwise, some other lubricating greases were added into polyuera grease, such as lithium ([8] Komiya et al. , 2004) and calcium ([9] Okaniwa et al. , 2002) soap. Furthermore, some new organic groups were also introduced into the polyurea, like acid amide ([10] Okaniwa et al. , 2001) and imide ([11] Parthiban and Naithani, 2001) in order to get some higher performance lubricating grease.

However, modern technology is giving some new requirements for the lubricating grease, and on the other hand, there are also some weaknesses for the existing diurea grease, especially its lower anti-shear stability. In this work, in order to meet the new industrial requirements and improve the weaknesses of diurea grease, the tetraurea grease has been synthesized by multi-steps for the first time. Furthermore, the properties of the tetraurea were tested by the ASTM method.

Experiment

The isocyanate (diphenylmethane-4,4[variant prime]-diisocyanate) and base oil (500SN mineral oil, kinematic viscosity at 40°C is from 92 to 98 mm² /s, viscosity index is 93) were added...