JPH05239483A - Lubricating oil composition for engine - Google Patents

Abstract

PURPOSE:To provide the subject composition which has such excellent performance in, e.g. preventing the seizure under load and reducing the friction as to make it possible to cope with the higher output and higher rotational speed of an engine and which can disperse graphite fluoride well. CONSTITUTION:This composition contains as the essential constituents 0.01-5wt.% graphite fluoride and 5-50wt.% compound comprising a bis-type alkenylsuccinimide or its derivative, having 20-60 polyamino groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine lubricating oil composition, and more particularly to an engine lubricating oil composition in which fluorinated graphite as an essential component can be well dispersed.

[0002]

2. Description of the Related Art Recent improvements in automobile technology have led to higher engine output and higher engine speed. Therefore, the demand for engine lubricating oil (hereinafter also referred to as engine oil) is increasing year by year. In particular, prevention of load seizure and reduction of friction are required.

In order to meet such demands, conventional engine oils are prepared by adding various solid and liquid additives to lubricating oils such as mineral oils, synthetic oils and animal and vegetable oils. Among such additives, it is known that fluorinated graphite represented by (CF) _n or (C ₂ F) _n is useful as a typical solid lubricant.

Fluorinated graphite is an inorganic polymer compound obtained by reacting fluorine and carbon, and the molar ratio of carbon to fluorine is usually 1: 1 to 1: 0.5 which is white or It is an off-white powdery substance. This fluorinated graphite is
It is a substance that is extremely stable thermally and chemically, and has superior performance to molybdenum disulfide as a solid lubricant.

However, fluorinated graphite has a property that it is extremely difficult to adapt to oil as well as to water.
For this reason, fluorinated graphite is poor in dispersion stability in lubricating oil, and sometimes aggregates and sediments to become solid or clay-like, which makes redispersion impossible.

In order to improve the dispersion stability of such a fluorinated graphite in oil, various studies have been conducted so far. For example, a technique of dispersing fluorinated graphite in oil with a dispersant having a propylene oxide group (for example,
Japanese Patent Publication No. 60-56760), a technique in which a dispersant having an oxybutylene group and a carboxylic acid type surfactant are used in combination to improve the dispersion stability (JP-A-2-24289).
No. 3).

However, since the dispersant having a propylene oxide group lacks stability at low temperatures, and the surfactant lacks stability at high temperatures, both of the above techniques are practically extremely limited.

An object of the present invention is to solve the above-mentioned drawbacks of conventional lubricating oils and to provide an engine oil composition having excellent dispersibility of fluorinated graphite.

[0009]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventor has (1) added to a base oil as an ashless dispersant in a conventional engine oil. The alkenyl succinimide or its derivative having the effect of improving the dispersibility of the fluorinated graphite in the base oil to a certain extent, (2) Among the above alkenyl succinimide or its derivative, In particular, those having a specific number of polyamino groups are highly effective in improving the above, and (3) the alkenyl succinimide or its derivative is preferably a bis type.
The present invention has been completed and the present invention has been completed.

That is, the present invention is about 0.0% fluorinated graphite.
1 to 5% by weight and a bis-type alkenyl succinimide or a derivative thereof, which is about 5 to 50% by weight of a compound having about 20 to 60 polyamino groups, as essential components. The subject is an engine lubricating oil composition.

Usually, the alkenyl succinimide or its derivative, which has been used as an ashless dispersant for engine oils, has 5 to 10 polyamino groups. On the other hand, the polyamino group of the bis-type alkenyl succinimide or its derivative of the composition of the present invention has a polyamino group content of about 20-6.
0, preferably about 30-50. The polyamino group is
If the amount is too small or too large, the effect cannot be obtained. If the amount is too large, the cost of the alkenyl succinimide or its derivative increases, which is economically disadvantageous. Here, the polyamino group means a group having two or more amino groups. The bis-type alkenyl succinic acid has the general formula shown in Chemical formula 1.

[0012]

[Chemical 1]

In the formula (1), R ₁ and R ₂ represent a polybutenyl group, R ₃ represents a divalent saturated aliphatic hydrocarbon group having 2 to 5 carbon atoms, and m represents an integer of 20 to 60. ..

The bis-type alkenyl succinimide or its derivative of the composition of the present invention is generally obtained by reacting polybutene with maleic anhydride and then imidizing it with polyamine, or the obtained imide is aromatic. Those obtained by reacting a polycarboxylic acid to partially amidate the remaining amino groups are used.

The composition ratio of the alkenyl succinimide or its derivative in the composition of the present invention is about 5 to 50.
%, Preferably about 10-40% by weight, more preferably about 20-35% by weight. If the amount of addition is too small, the dispersion stability of fluorinated graphite is not sufficient, and if it is too large, this effect saturates, which is economically disadvantageous.

Further, in the composition of the present invention, the other essential component, fluorinated graphite, is preferably in the form of particles, and the average particle size is usually about 0.01 to about 5 μm, preferably about 0.1.
The particle size is preferably in the range of from about 2 μm to have a uniform particle distribution as much as possible. Fluorinated graphite has a particle size of about 0.01μ
If it is less than m, the lubricating properties of the composition of the present invention cannot be improved, and if it is more than about 5 μm, aggregation and sedimentation occur, which is not preferable.

The blending ratio of the fluorinated graphite in the composition of the present invention is about 0.01 to about 10% by weight, preferably about 0.1 to about 5% by weight. If the amount added is too small, the lubricating properties of the composition of the present invention cannot be improved. On the contrary, if the amount is too large, fluorinated graphite aggregates and precipitates and is expensive, which is not preferable.

In the composition of the present invention, in addition to the above-mentioned essential components, metallic detergents, antiwear agents, antioxidants, corrosion inhibitors, viscosity index improvers, pour point depressants, defoamers, etc. Various additives may be contained. As the metal type detergent, alkali metal salicylate, alkali metal phenate, alkali metal sulfonate, etc. can be used,
As the antiwear agent, zinc dialkyldithiophosphate and the like can be used, as the antioxidant, amine-based and phenol-based antioxidants can be used, and as the corrosion inhibitor,
Benzotriazole, alkenyl succinate, etc. can be used. The blending ratio of these additives is generally about 0.1 to about 5% by weight.

As the viscosity index improver, polymethacrylate, olefin copolymer, etc. can be used, as the pour point depressant, polymethacrylate, etc. can be used, and as the defoaming agent, silicon compound, etc. can be used. .. The mixing ratio of these additives is about 20% by weight or less, preferably about 10% by weight or less.

The composition of the present invention described in detail above can be used as a gasoline engine oil, a diesel engine oil, etc., and as a fluorinated graphite mother liquor together with other additives, a base oil (mineral oil, synthetic oil, vegetable oil, etc.). It is used as a base oil for ordinary engine oils).

Even when the composition of the present invention is used as a fluorinated graphite mother liquor, the blending ratio of the fluorinated graphite in the engine oil obtained by blending the composition of the present invention as the fluorinated graphite and the bis-type alkenyl amber The compounding ratio of the acid imide or its derivative may be the same as that of the composition of the present invention, that is, about 0.01 to 5% by weight of fluorinated graphite and 5 to 50% by weight of bis-type alkenylsuccinimide or its derivative. is important.

[0022]

It is presumed that the engine lubricating oil composition of the present invention exhibits the following synergistic action by mixing the fluorinated graphite with the specific alkenylsuccinimide or its derivative. That is, the repulsive action due to the electric double layer due to the polyamino group in the specific alkenyl succinimide or its derivative is improved with the increase of the polyamino group, and the dispersive action of the fluorinated graphite is also improved with the improved repulsive action. It is supposed to be. However, even if the polyamino group is increased too much, the effect is saturated and a large amount of polyamino group is required, which is economically disadvantageous. For this reason,
In the lubricating oil composition for engines of the present invention, an alkenyl succinimide or a derivative thereof having a polyamino group number of about 20 to 60, preferably about 30 to 50 is used. The detailed operation of the above is unknown.

[0023]

【Example】

Examples 1-11, Comparative Examples 1-7 Inventive and comparative engine lubricating oil compositions were prepared with the compositions shown in Tables 2-7. The performances of the present invention and comparative engine lubricating oil compositions were evaluated by the following three tests, and the results are also shown in Tables 2-7.

1. Storage stability test: 10 lubricating oil compositions
Transfer to a 0 ml sample bottle and store under the following conditions. (1) Leave at room temperature (2) Leave at high temperature (constant bath 60 ° C.) Then, the dispersion stability is determined by the number of days when sedimentation starts.

2. Centrifuge test: Weigh about 5 g each of the invention and comparative engine lubricating oil compositions and transfer to a centrifuge test tube. An ultracentrifuge for separation used to separate the sludge component of the engine oil (Hitachi Ltd. product name "55
P-7 ") is used to centrifuge each of the engine lubricating oil compositions under the conditions of 5000 rpm and 60 minutes. Next, a pre-weighed membrane filter (pore size 0.02 μm) (manufactured by Millipore, USA) is used. Product name "Millipore
Using a membrane filter), filter the fluorinated graphite that has settled in the test tube after the above centrifugation.
The filtered membrane filter is weighed, and the sedimentation rate of the fluorinated graphite is calculated by the equation 1, and the sedimentation rate is used to determine the dispersion stability.

[0026]

[Equation 1]

3. Friction coefficient measurement: Friction coefficient is
Specimen tester (trade name "FAL manufactured by FALEX, USA
EX # 6 ″) is used to perform the measurement under the conditions shown in Table 1, and the friction coefficient reduction rate is calculated by the calculation shown in Formula 2.

[0028]

[Table 1]

[0029]

[Equation 2]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

[0033]

[Table 5]

[0034]

[Table 6]

[0035]

[Table 7]

The engine lubricating oil composition of the present invention is shown in Tables 2 to 2.
As is clear from the results of the storage stability test and the fluorinated graphite sedimentation rate in Table 4, it can be seen that all exhibit excellent dispersibility. On the other hand, in Comparative Example engine lubricating oil compositions, as is clear from Tables 5 to 6, after 10 days of standing at room temperature, sedimentation had already occurred, and compared with the engine lubricating oil compositions of the present invention, fluorination It can be seen that the dispersibility of graphite is inferior. Regarding the friction reducing effect, it is clear from Table 7 that the effect of reducing the friction coefficient is greater in the case where the fluorinated graphite is added than in the case where the fluorinated graphite is not added. Moreover, Table 7
From the above, even if the engine lubricating oil composition of the present invention is used as a fluorinated graphite mother liquor and blended with a base oil together with other additives, the dispersibility of the fluorinated graphite is not impeded at all, and the excellent fluorinated graphite is excellent. It can also be seen that the wear reduction effect can be obtained.

[0037]

As described in detail above, according to the engine lubricating oil composition of the present invention, the dispersibility of fluorinated graphite is improved, and the load seizure prevention and friction necessary for a high-power, high-rotation engine are prevented. It can be used as an engine oil having excellent performance such as reduction. Further, the engine lubricating oil composition of the present invention can also be used as a fluorinated graphite mother liquor, and when blended in a base oil together with other required additives, the dispersibility of the fluorinated graphite is not impaired, It is possible to obtain an engine oil having excellent performance required for a high-output, high-rotation engine.

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Claims (1)

[Claims] 1. A fluorinated graphite in an amount of 0.01 to 5% by weight, and a bis-type alkenyl succinimide or a derivative thereof having a polyamino group number of 20 to 60.
The engine lubricating oil composition is characterized by comprising ˜50% by weight as an essential component.