METHOD OF PREPARING ADDITION AGENT TO LUBRICATING OILS Russian patent published in 1999 - IPC

FIELD: chemical industry. SUBSTANCE: addition agent is prepared by reacting mixture of C₃-C₁₀-alcohols with phosphorus pentasulfide followed by two-stage neutralization of the resulting mixture of dialkylthiodithiophosphoric acids with zinc oxide when adding zinc oxide in amount of 0.8-2.5 g-mole per g-mole of mixture of dialkylthiodithiophosphoric acids in first stage followed by addition of the remaining dialkyldithiophosphoric acids at total ratio of mixture of acids of 1.74-1.82 g-mole per 1 g-mole of zinc oxide. Method makes it possible to prepare thermally stable addition agent with pH of 5.8-6.2 when using small amount (11-14%) of zinc oxide in excess of stoichiometric amount. EFFECT: more efficient preparation method.