| abstract |
Compositions containing sulfur and prepared by sulfurization of (A) at least one fatty acid ester of a polyhydric alcohol, or (B) at least one fatty acid, a fatty acid ester of a monohydric alcohol or a mixture of these, or (C) at least one aliphatic olefin containing about 8 to 36 carbon atoms, or (D) a mixture of two or more of these, (E) in the presence of a catalytic amount of acid phosphoric acid, a phosphoric acid salt, a phosphoric acid ester or a mixture thereof. It is preferably mixtures of (A), (B) and (C) which are sulfurized and the mixtures will preferably contain about 2 to 200 parts of (B) and about 25 to 400 parts of (C). The incorporation of a catalytic amount of phosphoric acid, a phosphoric acid salt such as sodium orthophosphate, a phosphoric acid ester or a mixture thereof results in the preparation of sulfurized compositions , which are characterized by higher sulfur contents, the compositions appear less colored when compared to sulfurized compositions prepared in the absence of such catalysts. The sulfurized compositions prepared according to the present invention are useful as antioxidants and as friction modifiers for lubricating compositions and, in particular, as lubricant additives in metalworking. |