Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Nitrogen and heavy metal – or nitrogen and aluminum – in the...
Patent
1996-07-29
1999-07-20
Howard, Jacqueline V.
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Nitrogen and heavy metal, or nitrogen and aluminum, in the...
508371, C10M13518
Patent
active
059256001
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a lubricant composition combining a combination of additives providing antiwear properties and a combination of additives providing antioxidant properties.
It is well known to include antiwear additives and antioxidants in lubricating oils such as engine oils. Antiwear additives are included to reduce the wear occurring when two metal surfaces rub together, i.e. boundary lubrication regimes, such as is found in valve trains in internal combustion engines. As well as reducing the operational lifetime of the metal parts, wear has the disadvantage that it releases metal contaminants into the lubricating oil which tend to accelerate the formation of engine oil sludge. It is believed that the antiwear additive acts to provide a protective film over the metal surfaces. Antioxidants are included to protect against sludge formation. Sludge is formed in engines as the result of a complex degradation of the lubricating oil in service. A number of interacting factors are believed to cause degradation including the engine design--particularly the recirculation of crankcase blow-by gases, fuel quality, oil consumption and vehicle operation, especially stop-go "city" driving. The net effect of these factors is a concentration of harmful contaminants in the lubricating oil leading to oxidative degradation of the oil which results in a thickened sludgy oil with reduced lubrication qualities. This thickened oil can also deposit in the engine with harmful effects.
It is recognised that dispersant additives are effective at reducing sludge deposition by solubilising the contaminants in the oil. However, dispersants have the disadvantage that they merely minimise sludge drop-out rather than prevent the initial degradation of the oil. Although dispersive action is important, the combined prevention of engine wear (thereby reducing metal contamination) and lubricant oxidation (thereby reducing oil thickening) will minimise oil degradation which is a major factor in sludge formation. The identification of effective antiwear and antioxidant additives are therefore important for the development of high performance engine oils.
One well known compound which provides both antiwear and antioxidant properties is zinc dialkyldithiophosphate ("ZDDP"). Generally ZDDP is employed at treat levels of 1 to 2 wt. % based on the total weight of the lubricating oil, which gives a phosphorus level in the lubricant typically in the range of from 0.05 to 0.15 wt. %, and a zinc level from 0.1 to 0.2 wt. %. In recent years there has been increasing concern that lubricant ash levels, such as that produced by the zinc in ZDDP. contribute to particulate emissions in the exhaust fumes from internal combustion engines. There is also concern that the phosphorus from the lubricant tends to poison catalysts used in catalytic converters, thereby preventing them from functioning to full effect.
Applicant's co-pending GB applications 93188951.1 and 9318923.1 both filed on the same day as the present application and both entitled "Lubricant Composition containing Antiwear Additive Combination" describe antiwear agents with reduced phosphorus and reduced or eliminated zinc content.
We have found that improved antioxidant performance can be obtained by combining the antiwear additive combinations disclosed in these patent applications with certain antioxidant combinations.
Accordingly the present invention provides a lubricant composition comprising a base oil and a combination of additives comprising: dithiophosphate, zinc diaryldithiophosphate, zinc alkylaryldithiophosphate, zinc arylalkyldithio-phosphate and mixtures thereof, greater than 1:1.
The present invention has the advantage that it provides a lubricant composition with good antiwear properties, whilst achieving low ash and phosphorus levels, and combines this antiwear system with enhanced oxidation performance by using the antioxidant additive combination as defined above, provided the amine and phenolic components of the antioxidant combination are used with a specific range
REFERENCES:
patent: 2739122 (1956-03-01), Kennerly
patent: 4116874 (1978-09-01), Sugiura et al.
patent: 4369119 (1983-01-01), deVries
patent: 4370246 (1983-01-01), deVries
patent: 4529526 (1985-07-01), Inoue et al.
patent: 4692256 (1987-09-01), Umemura et al.
patent: 4832867 (1989-05-01), Seiki et al.
Mortier, RM. Chemistry and Technology of Lubricants, pp. 94-99, 108-109. Blackie, Glasgow & London, 1992.
Exxon Research and Engineering Co.
Howard Jacqueline V.
Toomer Cephia D.
LandOfFree
Lubricant composition containing combination of antiwear and ant does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lubricant composition containing combination of antiwear and ant, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lubricant composition containing combination of antiwear and ant will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1321784