New Type of Antiwear Additives Based on Quaternary Ammonium Salts of Dialkyldithiocarbamic Acids for Silicone Lubricants

Abstract—

A method is proposed for the preparation of antiwear additives based on quaternary ammonium salts of dialkyldithiocarbamic acids by non-catalytic interaction of stoichiometric amounts of the corresponding diamine, carbon disulfide, and tetraalkylammonium chloride in the presence of sodium hydroxide in which the interaction of the initial components is carried out in one stage. All synthesized additives are highly soluble in polyorganosilicone oils, and at a concentration of 0.5–1.0 wt % they exhibit antiwear activity, which is expressed in a significant decrease (in some cases more than twice) in the diameter of the wear scar when tested on a four-ball friction machine. It has been shown that an increase in the length of alkyl groups in the anionic part of the additives leads to a more effective antiwear effect, the same trend manifests itself with an increase in the number of carbon atoms of alkyl groups in ammonium salts. The influence of the concentration of additives on the antiwear properties of lubricating compositions has been studied. The proposed type of additive is a promising friction modifier for silicone lubricants.