Abstract: In conventional production process of urea-based grease, direct reaction between amines and isocyanates in the base oil is a required step. However, the toxicity of isocyanates poses as a significant challenge for industrial safety. In this paper, a new route of producing polyurea based grease was studied through a two step method. The first step is to prepare polyurea thickener through reacting organic amines and isocyanates in selected organic solvent systems. The obtained thickener was then dried and can be used to prepare polyurea grease. The structure and toxicity of the premade thickener was analyzed by IR, and the results showed that this thickener having the typical structure of polyurea thickener was nontoxic. Polyurea grease prepared with this premade thickener had high drop point and exhibited good colloid stability, as well as thermal and oxidation stability, with low leakage and corrosion when use in bearing.

Key words: polyurea grease, thickener, preparation, toxicity