Lubricating oil compositions

Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic nitrogen compound

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508545, 508559, 44412, 44432, 44433, C10M14900, C10M13300

Patent

active

059453885

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to lubricating oil compositions and in particular to lubricating oil compositions suitable for medium or low speed diesel engines, typically the four-stroke trunk-piston engine.
Lubricating oils for medium or low speed diesel engines are known and will typically contain a range of additives which will perform a variety of functions, for example they may comprise dispersants to minimise deposit formation in various parts of the engine or detergent additives. However contamination of these lubricating oil compositions with unburnt residual fuel oil is a problem recognised in the industry. This leads to severe engine cleanliness problems in service which is sometimes referred to as "black paint". The problem is particularly widespread in 4-stroke trunk-piston engines where dirty cam boxes and crankcases are encountered. However, the problem is not confined to 4-stroke engines. 2-stroke cross-head engines can also suffer from the problem. These 2-stroke engines will usually use two separate lubricating oils, one for the crankcase and one for the cylinder, but it is in the crankcase where the heavy deposits potentially occur.
It might be expected that the problem would be overcome simply by using more of the conventional dispersant additive in the lubricating oil but this measure has met with very limited success. However, we have now found that the aforementioned problem is solved by including in the lubricating oil compositions a hydrocarbyl-substituted amine or polyamine.
Thus according to the present invention there is provided a lubricating oil composition suitable for use in low or medium speed diesel engines comprising a fuel oil with a residual oil content characterised in that the lubricating oil composition further comprises a hydrocarbyl-substituted amine or polyamine.
The lubricating oil composition of the present invention will be suitable for use in either a low or medium speed engine especially a marine diesel engine. Typically such an engine can be a 4-stroke trunk piston engine having an engine speed of 50-1,000 rpm e.g. 100-500 rpm, and a brake horse-power (BHP) per cylinder of 10-3,000 preferably 250-2,000. The engine can also be a 2-stroke cross-head engine having a speed of 40-1,000 rpm preferably 100-500 rpm and a brake horse-power per cylinder of 100-8,000.
In a further aspect of the present invention there is provided a method of reducing deposits in a low or medium speed diesel engine comprising lubricating the moving parts of the engine with a lubricating oil composition suitable for use in such an engine which comprises a fuel oil with a residual oil content characterised in that the lubricating oil composition further comprises a hydrocarbyl-substituted amine or polyamine.
The lubricating oil compositions of the present invention will have a TBN in the range 0.1 to 100 mgKOH/g. Where the composition is to be used in a 4-stroke trunk piston engine the TBN is preferably in the range 5-70, more preferably 8-50 mgKOH/g; where it is to be used in a 2-stroke cross-head engine and particularly for the crankcase, the TBN of the composition is preferably 0.1 to 15, more preferably 1 to 10 mgKOH/g.
The lubricating oil composition of the present invention will usually be a monograde lubricant i.e. one which exhibits little or no viscosity index improvement properties e.g. an SA30 oil.
As regards the lubricating oil, this may be any oil suitable for the lubrication of a low or medium-speed diesel engine particularly a marine diesel engine. The lubricating oil may suitably be an animal, a vegetable or a mineral oil. Suitably the lubricating oil is a petroleum-derived lubricating oil, such as a naphthenic base, paraffin base or mixed base oil. Alternatively, the lubricating oil may be a synthetic lubricating oil. Suitable synthetic lubricating oils include synthetic ester lubricating oils, which oils include diesters such as di-octyl adipate, di-octyl sebacate and tri-decyl adipate, or polymeric hydrocarbon lubricating oils, for example liquid polyisobutene and poly-a

REFERENCES:
patent: 3438757 (1969-04-01), Honnen et al.
patent: 3565804 (1971-02-01), Honnen et al.
patent: 3755433 (1973-08-01), Miller et al.
patent: 3844958 (1974-10-01), Anderson et al.
patent: 5015404 (1991-05-01), Kubo et al.
CRC Handbook of Lubrication, vol. I, Application and Maintance, "Medium Speed Engines" & Marine Equipmen, Booser, Ph.D., CRC Press, Inc. Florida, 1983, pp. 74-81 & 227-234.
International Search Report for Application No. PCT/GB94/02047; Date Mailed: Jan. 2, 1995.
MER, Jul. 1996, "Countering `Black Sludge` and `Black Paint`", pp. 22-24.
A. Montaud et al., Fifth CEC International Symposium on the Performance Evaluation of Automotive Fuels and Lubricants, May 13-15, 1997, "Effects and Determination of Raw Fuel Dilution in Marine Crankcase Lubricants".
P. Mullins, Technology Review, Diesel & Gas Turbine Worldwide, pp. 44-48, Dec. 1992, "The Changing Scene in Engine Lubrication".
Database WPI, Week 7503, Derwent Publications Ltd., London, GB, AN 75-04013W Oct. 12, 1974.
Database PWI, Week 9230, Derwent Publications Ltd., London, GB, AN 92-242666, Feb. 27, 1992.

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