| abstract |
Sulfur-containing compositions which are prepared by sulfurizing (A) at least one fatty acid ester of a polyhydric alcohol, or (B) at least one fatty acid, fatty acid ester of a monohydric alcohol, or a mixture thereof, or (C) at least one aliphatic olefin containing from about 8 to about 36 carbon atoms, or (D) mixtures of any two or more of (A), (B) and (C), (E) in the presence of a catalytic amount of phosphoric acid, a phosphoric acid salt, a phosphoric acid ester, or a mixture thereof. Preferably mixtures of (A), (B) and (C) are sulfurized in accordance with the invention and the mixtures preferably will contain from 2 to about 200 parts of (B) and from about 25 to about 400 parts of (C). The incorporation of a catalytic amount of phosphoric acid, a phosphoric acid salt such as sodium orthophosphate, phosphoric acid ester, or a mixture thereof results in the preparation of sulfurized compositions which are characterized by higher sulfur contents, and the compositions are lighter in color when compared to sulfurized compositions prepared in the absence of such catalysts. The sulfurized compositions prepared in accordance with the present invention are useful as general purpose antioxidants and friction modifiers for lubricating compositions, and in particular, as additives in metal working lubricants. |