Antiwear Additives for Neopentyl Type Esters: Design and Performance Evaluation of Amine Salts of Phosphonic Acid

摘要

Antiwear properties of phosphonic acid derivatives in trimethylolpropane (TMP) esters were investigated under boundary lubrication conditions. The effect of the molecular structure of phosphonic acid derivatives on antiwear properties was observed. Computer-assisted chemistry was applied to explain the phenomena. The dipole moment of derivatives was calculated using the molecular orbital method. A good relationship of dipole moment of the derivatives with their antiwear properties was found. Antiwear properties of dialkyl phosphonates depend on the polarity of the base fluid. The nonpolarity index (NPI) of a TMP ester molecule was calculated to explain the phenomena. TMP esters have NPI in the 34.3-185.5 range. Dialkyl phosphonates provide good antiwear properties in less polar TMP esters, whereas their antiwear properties are insufficient in polar TMP esters. Antiwear properties of dialkyl phosphonates in mixture of trimethylolpropne esters were also investigated. Amine salts of phosphonic acid were designed as a new antiwear additive system for TMP esters by using computer assisted chemistry. Excellent antiwear properties of the salts was confirmed, even in polar base fluid.