Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Reexamination Certificate
1999-10-21
2001-10-23
Johnson, Jerry D. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
C508S391000, C508S398000, C508S399000, C508S433000, C508S440000, C508S460000, C508S586000
Reexamination Certificate
active
06306801
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lubricating oil composition, and more particularly, to a lubricating oil composition which is excellent in sludge formation inhibiting effect, and hence is suitable especially for use as an engine oil.
2. Background Art
In a gasoline engine, sludge is formed due to the oxidative deterioration of an engine oil at high temperatures, and the reaction between the engine oil and unburnt fuel, blow-by gas (especially NO
x
), or the like. The sludge formed causes engine troubles such as blockage of an oil path or a valve, and an increase in viscosity of the engine oil. Therefore, the engine oil is required to be capable of inhibiting the sludge formation as much as possible so as not to cause the engine troubles. The engine oil has been used under very severe conditions with the trend toward the higher output of a gasoline engine and the smaller capacity of an oil pan for the engine, oil for the purpose of saving energy especially in recent years. Accordingly, a higher sludge formation inhibiting effect has been required of the engine oil.
The engine oil is generally manufactured by adding additives such as ashless dispersant, friction inhibitor, and metallic detergent to a lubricating base oil. In general, polybutenylsuccinimide has been used as the ashless dispersant in conventional engine oils. However, the sludge formation inhibiting effect exerted by polybutenylsuccinimide has still been unsatisfactory for establishing the technology to increase the life of the engine oil.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a lubricating oil composition which exhibits an extremely excellent effect of inhibiting sludge formation, ensuring its longer life especially when the composition is used as a gasoline engine oil.
The present inventors have conducted intensive study to develop a lubricating oil more excellent in sludge formation inhibiting effect. As a result, they have found that a lubricating oil containing acylated bissuccinimide, zinc dithiophosphate, and a metallic detergent each in a specific amount has an extremely excellent sludge formation inhibiting effect. Thus, the present invention has been accomplished.
Namely, the present invention provides a lubricating oil composition which comprises: a lubricating base oil; (A) 0.5 to 20% by mass of acylated bissuccinimide; (B) 0.05 to 0.3% by mass of zinc dithiophosphate in terms of the phosphorus content; and (C) 0.5 to 4.0% by mass of a metallic detergent in terms of the sulfated ash content, based on the total mass of the composition.
The lubricating oil composition of the present invention exhibits an extremely excellent effect of inhibiting sludge formation, which ensures its longer life especially when the composition is used as a gasoline engine oil.
The lubricating oil composition of the present invention is preferably used especially as a gasoline engine oil. In addition, it is also preferably used as a lubricating oil which will suffer the troubles caused by sludge formation due to thermal/oxidative degradation, and the like of the lubricating oil. Specific examples of such a lubricating oil include diesel engine oils, two-cycle engine oils, automobile gear oils, ATF oils, non-stage transmission oils, shock absorber oils, and hydraulic actuation oils.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in more detail hereinafter.
As the lubricating base oil in the lubricating oil composition of the present invention, any mineral oils and/or synthetic oils serving as common lubricating base oils can be used.
As the mineral oils, oils of paraffinic series, naphthenic series, and the like, normalparaffins, and the like obtained in the following manner can be used. Specifically, for example, paraffinic or naphthenic crude oils are subjected to atmospheric distillation and vacuum distillation to produce a lubricating oil fraction. The resulting fraction is subjected to one or an appropriate combination of two or more of refining processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, washing with sulfuric acid, and clay treatment. When two or more refining processes are performed, the respective refining processes can be combined in any order, and the same refining process may be repeated plural times each under different conditions.
Although synthetic oils have no particular restriction, there can be used one or more compounds selected from poly-&agr;-olefins such as 1-octene oligomer, 1-decene oligomer, ethylene-propylene oligomer, and the like, and hydrides thereof, isobutene oligomer and hydrides thereof, isoparaffin, alkylbenezene, alkylnaphthalene, diesters such as ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexylsebacate and the like, polyol esters such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethyl hexanoate, pentaerythritol pelargonate, and the like, polyoxyalkylene glycol, dialkyldiphenyl ether, polyphenyl ether, and the like.
As the lubricating base oils to be used in the present invention, a mixture of the mineral lubricating base oil and synthetic lubricating base oil in any proportions, so-called semi-synthetic oils can also preferably be used.
Although the kinematic viscosity at 100° C. of the lubricating base oil to be used in the present invention have no particular restriction, it is preferably in a range of 1.0 to 10 mm
2
/s, more preferably in a range of 2.0 to 8 mm
2
/s.
When the kinematic viscosity at 100° C. of the lubricating base oil is 1.0 mm
2
/s or more, it becomes possible to obtain a lubricating oil composition more excellent in lubricity due to sufficient oil film formation, with lower evaporation losses of the base oil under high temperature conditions. Whereas, with a kinematic viscosity at 100° C. of 10 mm
2
/s or less, it becomes possible to obtain a lubricating oil composition having decreased flow resistance and hence decreased friction resistance at the site of lubrication.
Although the viscosity index of the lubricating base oil also has no particular restriction, it is preferably 80 or more, more preferably 100 or more. A viscosity index of 80 or more can result in a lubricating oil composition more ensuring the compatibility between its oil film forming capability and flow resistance reducing capability.
Although the pour point of the lubricating base oil also has no particular restriction, it is preferably 0° C. or less, more preferably −5° C. or less. A pour point of 0° C. or less can result in a lubricating oil composition whereby the operation of a machine is less hindered at low temperatures.
The component (A) in the lubricating oil composition of the present invention is acylated bissuccinimide.
Specific examples of the acylated bissuccinimide include compounds represented by the following general formula (1):
where R
1
and R
2
are each independently a straight or branched alkyl or alkenyl group having 40 to 400 carbon atoms. Examples of R
1
and R
2
include branched alkenyl groups and branched alkyl groups which are hydrides of branched alkenyl groups, derived from polypropylene, ethylene-propylene oligomer, polyisobutylene, and the like, having a number-average molecular weight of 1000 to 2000.
In the above formula (1), R
3
denotes a hydrogen atom, an alkyl or alkenyl group having 1 to 24 carbon atoms, an alkoxy group having 1 to 24 carbon atoms, or a hydroxy(poly)oxyalkylene group represented by the following formula (2):
—O&Parenopenst;R
4
O&Parenclosest;
c
H (2)
Specific examples of the alkyl or alkenyl group having 1 to 24 carbon atoms referred to herein include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, and tetracosyl groups (these alkyl groups
Kurosawa Osamu
Matsuyama Yoko
Yagishita Kazuhiro
Johnson Jerry D.
Nippon Mitsubishi Oil Corporation
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