PURPOSE: To obtain a lubricant oil having improved oxidative stability capable of preventing wear of an internal combustion engine without damaging a catalyst for purifying exhaust gases, by adding a specific compound to a synthetic lubricant, etc.
CONSTITUTION: An aqueous dispersion of 1 mole of molybdenum trioxide powder is reacted with an aqueous solution of 1.4 mole of sodium hydrosulfide, the pH of the resulting mixture is adjusted to 3,75 and butanol is added to the mixture. The mixture is reacted with a 1.1 moles of dialkylamine having 8-18C alkyl group and 1.1 mole of carbon disulfide to give a molybdenum sulfide dialkyldithiocarbamate shown by the formula I:(R1 and R2 are 8-18C alkyl; R3 and R4 are alkyl or alkylphenyl; x = 1.3-2.1; y = 1.9-2.7; x + Y = 4). The addtion of a compound shown by the formula I in a molybdenum concentration of 0.01-0.085 wt.%, or in combination with a zinc dithiophosphate shown by the formula II in an amount not more than 0.7 wt.% improves greatly wear and oxidation resistance.
MAEDA TSUTOMU
MAEDA YOSHIHIRO
TANABE TOSHIO
HANDA TAKUROU
NISHIHARA AKIO
KATOU HIDEKATSU
NIPPON MINING CO