Amine type antioxidant
Generally, phenolic antioxidants are used in internal combustion engine oil, hydraulic oil and transformer oil with relatively low temperature range. The amine type antioxidant is used at a higher temperature than the phenol type. In particular, the alkyldianiline type antioxidant has good high-temperature antioxidant performance, which can be used in the synthesis of ester oil as the main antioxidant component of jet turbine engine lubricating oil. Amine antioxidants are mainly phenylenediamine antioxidants, diphenylamine antioxidants, phenyl - - naphthylamine antioxidants and phenothiazine antioxidants. When the mass fraction of 3, 5-diethyl toluene diamine is within 1%, the oxidation test results show that it can reduce the increase of oil viscosity and reduce bearing weight loss. N-benzamphenylenediamine is used in PAO or polyol esters, with significant antioxidant effect, and is more suitable for use with metal salts or metal activators, with little metal corrosion, little viscosity increase, and little sludge formation.
N ', N-diphenylp-phenylenediamine, whose phenyl can also be substituted by methyl, ethyl, or methoxy, is also an effective antioxidant. N, N- bis (2, 4-diaminodiphenyl ether) imine and N, N- bis (2, 4-diaminodiphenyl ether) imine can reduce the metal corrosion, and the viscosity and acid value of the oil are very small increase.
Aramidine antioxidants are mainly dialyldiphenylamine, diaminotoluene derivatives, 1, 8-diaminonaphthalene derivatives, etc. Dialkyl diphenylamine is widely used. Diphenylamine can be used in either single or double alkylation. Generally, the nitrogen mass fraction of alkyl diphenylamine is 2% ~ 6%. If the nitrogen content is too low, the effect of alkyl diphenylamine will be weakened. If the nitrogen content is too high, the compatibility and volatility of alkyl diphenylamine in lubricating oil will be adversely affected. Diphenylamine antioxidants are suitable for lubricating oils with rapid temperature rise and can prevent sludge formation in synthetic ester oils. Diphenylamine antioxidants are one of the important ash - free antioxidants. With the upgrading of oil specifications, higher requirements are put forward for the high-temperature antioxidant capacity of engine oil, which also leads to an unprecedented increase in the amount of amine antioxidants in engine oil. It has been reported that the combination of alkyl diphenylamine and molybdenum compounds can improve the oxidation and friction properties of lubricating oil, which is especially suitable for crankcase lubricating oil or transmission oil, including multi-stage non-phosphorous lubricating oil. The US patent reported that lubricants containing diphenylamine derivatives had continuously improved antioxidant capacity, and styrene-diphenylamine compounds had excellent anti-oxidation and anti-corrosion ability and good anti-coking effect. In ester oils, diphenylamine oligomers have better antioxidant properties than diphenylamine at high temperature.