微量の金属系清浄剤によるZnDTP分解抑制とメカニズム解明

抄録

Zinc dithiophosphate (ZnDTP) is widely used in hydraulic fluids. It is a multi-functional additive for lubricants providing benefit such as anti-wear, anti-corrosion, and anti-oxidation performance. It is thought that Zinc-containing hydraulic fluids had been inferior in sludge control and copper corrosion protection compared to non Zinc-containing fluids. The degradation of ZnDTP tends to generate sludge and sulfur compounds, which in turn, attack copper material in hydraulic pumps. Sludge and corrosion are detrimental to hydraulic circuit’s performance, with sludge causing filter blocking and valve sticking, and corrosion causing pump damage. However, it has recently been shown possible to reduce sludge and copper corrosion by combining low treatrate detergents with ZnDTP in hydraulic oil. This report shows the results of a study to understand how various detergents influence the control of sludge and the copper corrosion in the presence of ZnDTP. Furthermore, paying attention to the decomposition mechanism of ZnDTP, mentioned was made about the oxidation stability from a degradative intermediate. From these results, low treatrate particular type of metal detergents showed clearly to have controlled sludge generation and copper corrosion by contributing to the oxidization control from dithiophospate which carried out decomposition generation from ZnDTP.