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
1996-09-11
1997-12-09
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...
508364, 508365, 556 38, C10M13518
Patent
active
056960638
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a basic metal salt of dithiocarbamic acid and a lubricating oil composition containing said salt. A lubricating oil composition excellent in wear-resistant properties and friction-decreasing properties is obtained by adding a basic metal salt of dithiocarbamic acid to a lubricating base oil, specifically, to a hydrocarbon oil. The lubricating oil composition of the present invention is especially suitable as a lubricating oil for automotive internal combustion engines (an engine oil).
BACKGROUND OF THE INVENTION
Recently, as internal combustion engines such as automotive engines have gotten higher power, engine parts such as valve gear systems and cylinders have been placed under such severe conditions that they are exposed to high temperatures, and the frequency of contact per unit time between metals is increased. Under such severe conditions, the wear-inhibiting properties of an engine oil for engine parts such as these valve gear systems and cylinders have been regarded as being important.
To improve engine oil performance various kinds of additives have been compounded. For example, zinc dithiophosphate shows an excellent wear-inhibiting performance besides acting as an anti-oxidant and a corrosion inhibitor. From the aspect of both its multifunctionality and effect it is widely used in engine oils or in a hydraulic actuation oil. To improve the wear-inhibiting properties of engine oils an increase in an added amount of the zinc dithiophosphate has been conceived; however, since the phosphorus (P) in it poisons any exhaust emission purification catalyst and any oxygen sensor to significantly decrease the performance of an exhaust gas emission-control system, the added amount must be limited.
Thus the development of an additive for lubricating oils has been expected, said additive containing no phosphorus and having excellent friction-inhibiting properties; however, it has been difficult to find an additive showing a sufficient performance.
SUMMARY OF THE INVENTION
1. Disclosure of the Invention
One object of the present invention resides in providing a novel compound that can impart excellent wear-resistant properties to a lubricating oil when the compound is used as an oil additive for a lubricating oil.
Another object of the present invention resides in providing a lubricating oil composition excellent in wear-resistant properties and frictional characteristics and that is especially suitable for a lubricating oil for automotive internal combustion engines.
2. Means to Resolve the Problems
As a result of the extensive study by the inventors of the present invention to develop a lubricating oil containing no, or a very low content of, phosphorus, and having excellent wear-resistant properties, they found that when a basic metallic salt of dithiocarbamic acid was synthesized and its performance as an additive for lubricating oils was evaluated, a lubricating oil composition showing excellent wear-resistant properties and good frictional characteristics resulted, as compared with the case where a general-purpose zinc dithiophosphate or its corresponding neutral metallic salt of dithiocarbamic acid was added.
Among basic metallic salts of dithiocarbamic acid, those in which the average number of the carbon atoms of each of the lipophilic groups, such as an alkyl group, is more than 8, are excellent in solubility in base oils. The use of such a basic metallic salt of dithiocarbamic acid with an oil-soluble amine compound allows a further improvement in wear-resistant properties. The use of such a basic metallic salt of dithiocarbamic acid with a friction-decreasing agent results in a better effect in decreasing the coefficient of friction.
Wear-resistant properties of zinc dithiophosphate may be lost by a mutual action with another additive that may exist with it. For example, it was known that the wear-resistant properties were decreased by the coexistence with an oil-soluble amine compound such as succinic imide or an alkyl amine. Thus the
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Arai Katsuya
Tokashiki Michihide
Tomizawa Hirotaka
Cohen Harvey L.
Exxon Chemical Patents Inc.
Howard Jacqueline V.
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