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
1996-11-12
1998-02-17
Willis, Jr., Prince
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, C10M13700
Patent
active
057191093
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a lubricating oil composition, and more specifically, one excellent in wear-resistant properties and frictional characteristics. The lubricating oil composition of the present invention can be used as a lubricating oil for automotive internal combustion engines (engine oil), and also in a wide range of fields as gear oils, automatic transmission fluids (ATF), power-steering oils (PS oil), spindle oils, hydraulic fluids, and industrial lubricating oils.
BACKGROUND OF THE INVENTION
Since zinc dithiophosphates (below called "Zn-DTP") such as zinc dialkyldithiophosphates show an excellent wear-inhibiting performance, besides acting as an antioxidant and a corrosion inhibitor, they have been generally used as an additive for engine oils.
However, since phosphorus (P) contained in Zn-DTP poisons any automotive exhaust emission purification catalyst and any automotive oxygen sensor, an engine oil to which Zn-DTP is added has had a problem in that the performance of any exhaust-gas emission control system decreases significantly. Conventionally to resolve this problem a method of decreasing the added amount of Zn-DTP to lower the amount of phosphorus in the engine oil has been adopted. However, when the amount of Zn-DTP decreases, problems are caused such that the wear-resistant properties of the lubricating oil decrease and in that the engine durability decreases due to the wear of the valve-gear system. Thus while decreasing the added amount of Zn-DTP, other additives, such as an ash-free detergent dispersant and a metal detergent have been used with Zn-DTP to maintain performances necessary for an engine oil.
However, when both Zn-DTP and an ash-free detergent dispersant such as a polyalkenyl succinimide are used, a problem arises such that both compounds are the first to react in a base oil to result in the effects of Zn-DTP being masked and its activity being impaired. Accordingly, to attain sufficient wear-resistant properties, Zn-DTP must be used in a relatively high amount, and thus it has been difficult to decrease the phosphorus content.
SUMMARY OF THE INVENTION
1. Disclosure of the Invention
The object of the present invention resides in providing a lubricating oil composition excellent in wear-resistant properties and frictional characteristics.
2. Means to Resolve the Problems
As a result of the extensive study by the inventors of the present invention to resolve the above problems, they found that besides the wear-resistant properties of a lubricating oil being improved, the coefficient of friction of the oil significantly decreased by (1) adding to a lubricating base oil a complex of a metallic salt of dithiophosphoric acid (below called "M-DTP") with a primary alkylamine having a short chain and (2) containing in a lubricating base oil at least one kind of compound selected from the group consisting of an oxymolybdenum sulfide dithiocarbamate (below called "Mo-DTC"), an oxymolybdenum sulfide organophosphorodithioate (below called "Mo-DTP"), a fatty ester, and an organic amide compound.
Based on this finding they accomplished the present invention.
Thus according to the present invention a lubricating oil composition is provided by containing in a lubricating base oil (A) a complex obtained by reacting a metallic salt of dithiophosphoric acid having lipophilic groups, the average number of the carbon atoms of which is 4 or more, with a primary alkylamine having 8 or less carbon atoms, and (B) at least one kind of compound selected from the group consisting of an oxymolybdenum sulfide dithiocarbamate, an oxymolybdenum sulfide organophosphorodithioate, a fatty ester, and an organic amide.
DETAILED DESCRIPTION OF EMBODIMENT
The present invention will be described in detail below.
(Lubricating Base Oil)
Lubricating base oils used in the present invention are not specifically limited, and various kinds of conventionally-known mineral oils and synthetic lubricating oils can be used. Exemplified as the mineral oils are raffinates obtained
REFERENCES:
patent: 2977382 (1961-03-01), Millikan
patent: 3002014 (1961-09-01), Dinsmore et al.
patent: 3813336 (1974-05-01), Goldschmidt
patent: 4743389 (1988-05-01), Braid et al.
Tokashiki Michide
Tomizawa Hirotaka
Yamada Michiya
Exxon Chemical Patents Inc
Toomer Cephia D.
Willis Jr. Prince
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