JP2001187894A - Lubricating oil composition for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating oil composition for internal combustion engines which is used in a nitrogen oxide (NOx) gas atmosphere and is stably functional without any deterioration caused by the nitrogen oxide gas during use. SOLUTION: The lubricating oil composition for internal combustion engines contains (A) a base oil comprising a mineral oil and/or a synthetic oil wherein the viscosity at 100 deg.C is adjusted to 2 to 50 cSt and the aromatic iron content adjusted to <=2% either by distillation separation of a crude oil followed by a purification process or a further deep-dewaxing process or by adjusting the condition for the synthesis of the synthetic oil, and (B) an organic molybdenum compound, and is used in a nitrogen oxide gas atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition for an internal combustion engine used in a nitrogen oxide gas atmosphere, and more particularly to a lubricating oil composition used in a nitrogen oxide (NO _x ) gas atmosphere. The present invention relates to a lubricating oil composition for an internal combustion engine that functions stably without being deteriorated by a nitrogen oxide gas.

[0002]

Generally, a part of combustion gas in an internal combustion engine leaks into a crankcase as blow-by gas (blow-by gas) from between a piston and a cylinder. This is the combustion gas contains a fairly high concentration NO _X gas, which is a problem that deteriorates the crankcase oil (engine oil). By the way, recently, vehicles equipped with a reduction catalyst such as a three-way catalyst have been increasing for emission control measures, and it has been allowed to operate the internal combustion engine more severely (high speed and high output). As a result, there is a tendency that NO _X gas concentration of the combustion gas leaking into the crankcase is increased. Further, from the viewpoint of energy saving, for the purpose of improving fuel efficiency, weight reduction of automobile bodies has been promoted, and accordingly, crankcases have also been reduced in size, and accordingly, the amount of crankcase oil (internal combustion engine oil) has been reduced. . The main component in these reasons, in recent years NO _X gas concentration in the crankcase oil is been significantly increased, its effect is very large, are conventionally employed Zn- dithiophosphates (Zn-DTP) and the detergent-dispersant The internal combustion engine oil described above causes abnormal deterioration such as black sludge in a short time, and its improvement is desired.

[0003]

Means for Solving the Problems] The present inventors have solved the problems of conventional internal combustion engine oil such as described above, conducted extensive research to develop a stable engine oil to NO _x gases . As a result, they have found that a lubricating base oil having a specific property and an organic molybdenum compound blended with the lubricating base oil can achieve the intended purpose, and have completed the present invention. That is, the present invention provides a method of raising the viscosity at 100 ° C. of 2 to 50 cSt by distillative separation of crude oil, followed by purification treatment or further deep dewaxing treatment, or by adjusting synthetic oil synthesis conditions.
And a base oil composed of mineral oil and / or synthetic oil whose aromatic content is adjusted to 2% or less and (B) an organic molybdenum compound, for an internal combustion engine used in a nitrogen oxide gas atmosphere. A lubricating oil composition is provided.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION The properties of the base oil used in the lubricating oil composition of the present invention are those obtained by refining or further dewaxing after distilling and separating crude oil, or by adjusting synthetic oil synthesis conditions. In particular, the viscosity at 100 ° C. needs to be in the range of 2 to 50 cSt. Viscosity is 2c
If it is less than St, there is a disadvantage that the evaporation loss is large, and if it exceeds 50 cSt, the power loss due to viscous resistance is too large, which is not preferable. From such a point, the viscosity is preferably in the range of 3 to 20 cSt.

[0005] Further, the above lubricating base oil must have an aromatic content (% C _A ) adjusted to 2% or less. Here, those having an aromatic content exceeding 2% are NO _x
There is an inconvenience that deterioration in a gas atmosphere is remarkable. From this point, in the present invention, the aromatic content is 1%.
The content is more preferably 0.2% or less. In addition,
Other properties of the lubricating base oil include the properties required for conventional lubricating oils for internal combustion engines, such as suitable viscosity characteristics, good oxidation stability, good clean dispersibility, good rust and corrosion resistance, It is also preferable to have good low-temperature fluidity and the like,
More preferably, the viscosity index is 80 or more, the pour point is -10 ° C or less, particularly -20 ° C or less, and the total acid value is 0.1 mgKOH / g or less. The base oil used in the lubricating oil composition of the present invention comprises a mineral oil and / or a synthetic oil having the above properties.

As a method for preparing a mineral oil which can be used as a lubricating base oil having the above-mentioned properties, a paraffin-based crude oil or an intermediate-based crude oil is subjected to atmospheric distillation or a residual oil obtained by atmospheric distillation is distilled under reduced pressure. A refined oil preparation means for purifying the obtained distillate according to a conventional method, or a deeply dewaxed oil preparation means for further performing a deep dewaxing treatment after the purification is employed. The purification method at this time is not particularly limited, and various methods can be used. Usually, (a) hydrogenation treatment, (b) dewaxing treatment (solvent dewaxing or hydrodewaxing), (c) solvent extraction treatment,
(D) Alkali distillation or sulfuric acid washing treatment, and (e) clay treatment are performed alone or in an appropriate combination. It is also effective to repeat the same process in a plurality of stages. For example, hydrogenated distillate or hydrogenated, followed by alkali distillation or sulfuric acid washing, hydrogenated distillate, dewaxing, distillate oil solvent After the extraction process, the method of hydrotreating, performing two-stage or three-stage hydrotreatment on the distillate,
Alternatively, there is a method in which alkali distillation or sulfuric acid washing treatment is performed, and a method in which the above-mentioned treatments (1) to (4) are performed and then dewaxed again to obtain a deeply dewaxed oil.

[0007] The above means in the case of mineral oil, and by adjusting the synthesis conditions in the case of synthetic oils, the properties of the lubricating base oil obtained is prepared so that the viscosity of the foregoing and% C _A. In particular, in the present invention, mineral oil obtained by deep dewaxing is suitable as the lubricating base oil. This deep dewaxing treatment is performed by a solvent dewaxing method under severe conditions, a contact hydrodewaxing method using a zeolite catalyst, or the like. In the present invention, as the lubricating base oil, the above-mentioned mineral oil or alkylbenzene, polybutene or poly (α-
Olefins) or mixtures thereof.

In the present invention, the above lubricating base oil (A)
Was added with (B) an organic molybdenum compound, there is provided a lubricating oil composition for internal combustion engines used in the nitrogen oxide gas atmosphere, more excellent stability to the composition NO _x gas Is shown. Here, as the organic molybdenum compound (B), various compounds can be used, and there is no particular limitation. Specifically, Mo-dithiocarbamate (MoDTC) or Mo, which has been conventionally used as an extreme pressure agent, is used. −
Dithiophosphate (MoDTP) and the like.
The amount of the organic molybdenum compound (B) varies depending on the properties of the lubricating base oil described above as the component (A), the type of the organic molybdenum compound itself, and the like. ) For 100 parts by weight of base oil, (B)
The proportion of the organic molybdenum compound is preferably 0.05 to 2.0 parts by weight, more preferably 0.1 to 1.0 part by weight.

[0009] As described above, the lubricating oil composition of the present invention comprises:
But those obtained by blending the above (A) base oil (B) an organic molybdenum compound, if necessary, in order to impart a more excellent stability against NO _x gas, adding a phenolic antioxidant be able to. Various phenolic antioxidants can be used and are not particularly limited. Specifically, 4,4′-methylenebis (2,6
4,4′-bis
(2,6-di-tert-butylphenol); 4,
4'-bis (2-methyl-6-tert-butylphenol); 2,2'-methylenebis (4-ethyl-6-
2,2′-methylenebis (4-methyl-6-tert-butylphenol); 4,4′-butylidenebis (3-methyl-6-tert-butylphenol); 4,4′-isopropylidenebis (tert-butylphenol); 2,2'-methylenebis (4-methyl-6-nonylphenol); 2,2'-isobutylidenebis (4,6-ditert-butylphenol);
6-dimethylphenol); 2,2′-methylenebis (
4-methyl-6-cyclohexylphenol); 2,6
-Di-tert-butyl-4-methylphenol; 2,
6-di-tert-butyl-4-ethylphenol;
2,4-dimethyl-6-tert-butylphenol; 2,6-ditertiary α-dimethylamino-p-
Cresol; 2,6-ditert-butyl-4 (N,
N'-dimethylaminomethylphenol);4,4'-
Thiobis (2-methyl-6-tert-butylphenol); 4,4'-thiobis (3-methyl-6-tert-butylphenol); 2,2'-thiobis (4-
Methyl-6-tert-butylphenol); bis (3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide; bis (3,5-ditert-butyl-4-hydroxybenzyl) sulfide and the like. In the present invention, these phenolic antioxidants can be used alone or in combination of two or more.

The amount of the above-mentioned phenolic antioxidant is as follows:
It differs depending on the properties of the above-mentioned lubricating base oil, which is the component (A), the type of the phenolic antioxidant itself, and the like, and cannot be unambiguously determined, but is usually 100 parts by weight of the base oil (A). 0.05 to 2.0 parts by weight, preferably 0.1 to 1.0 parts by weight
The ratio is by weight. The lubricating oil composition of the present invention may optionally contain other various additives, for example, Zn-DT.
It is also effective to add an appropriate amount of P, a detergent / dispersant, a polymer and the like.

[0011]

Next, the present invention will be described in more detail with reference to examples. The sample oil was prepared by the various additives in addition to the base oil shown in Examples 1-3 and Comparative Examples 1-4 in Table 1, was subjected to NO _x deterioration test of the sample oils in the following manner. That is, in the above sample oil 50 ml, in the presence of an iron and copper catalyst (oxidation test JIS K-2514 test piece), a concentration of 1% nitric oxide (NO) gas was 6 l / hr and humidified air was 10 l. / Hr.
The temperature of the sample oil was kept at 135 ° C., and the time when abnormal deterioration (acid value rapidly increased) was started was measured. The results are shown in Table 1.

[0012]

[Table 1]

* 1 Phenolic antioxidants (4, 4 '
- methylenebis (2,6-di-tert-butylphenol) * 2 Zn-DTP, metallic detergent, ashless dispersant, * 3 solvent refined oils containing polymers such as [% C _A 8, viscosity 5.2CSt (100
° C.)]: distillate solvent extraction process from intermediate base crude - hydrotreated what * 4 solvent refined oil [% C _A 4, viscosity 5.4cSt (100
° C)]: Distillate from intermediate-base crude oil subjected to solvent extraction and hydrogenation treatment * 5 Two-stage hydrogenated oil [% C _A 0.2 or less, viscosity 5.5 cSt
(100 ° C)]: Two-stage hydrotreated distillate from intermediate base crude oil

[0014]

As described above, the lubricating oil composition of the present invention comprises:
There is provided a lubricating oil composition to be used under certain oxidizing atmosphere that nitrogen oxide gas atmosphere, NO _x
Is stable without being deteriorated, and therefore NO
_x Lubricating oils for internal combustion engines with high gas concentrations and at relatively high temperatures, such as gasoline engines and diesel engines, and gas engines such as natural gas, LPG (liquefied petroleum gas), cracked gas, coal cracked gas, etc. It is effectively used as fuel, such as crankcase oil for internal combustion engines.

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Claims (5)

[Claims] (A) The viscosity at 100 ° C. is adjusted to 2 to 50 cSt and the aromatic content is adjusted to 2 to 50 cSt by a purification treatment or a deep dewaxing treatment after distilling and separating a crude oil, or by adjusting synthetic oil synthesis conditions. %, Which is a lubricating oil composition containing a base oil composed of mineral oil and / or synthetic oil adjusted to not more than 0.1% and (B) an organic molybdenum compound and used in a nitrogen oxide gas atmosphere. Engine lubricating oil composition. 2. (A) For 100 parts by weight of base oil,
The lubricating oil composition for an internal combustion engine according to claim 1, comprising (B) an organic molybdenum compound in a ratio of 0.05 to 2.0 parts by weight. 3. The lubricating oil composition for an internal combustion engine according to claim 1, further comprising a phenolic antioxidant. 4. The method according to claim 1, wherein the phenolic antioxidant is 4,4′-
Methylenebis (2,6-di-tert-butylphenol); 4,4'-bis (2,6-di-tert-butylphenol); 4,4'-bis (2-methyl-6-tert-butylphenol); 2,2'- Methylene bis
(4-ethyl-6-tert-butylphenol);
2,2'-methylenebis (4-methyl-6-tert-butylphenol); 4,4'-butylidenebis (3
-Methyl-6-tert-butylphenol); 4,
4'-isopropylidenebis (2,6-ditert-butylphenol); 2,2'-methylenebis (4-methyl-6-nonylphenol); 2,2'-isobutylidenebis (4,6-dimethylphenol); 2,2'-
Methylenebis (4-methyl-6-cyclohexylphenol); 2,6-di-tert-butyl-4-methylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,4-dimethyl-6-tert-butylphenol; 2,6-ditertiary α-dimethylamino-p-cresol; 2,6-ditertiarybutyl-4 (N, N′-dimethylaminomethylphenol);
4,4'-thiobis (2-methyl-6-tert-butylphenol); 4,4'-thiobis (3-methyl-
2,2′-thiobis (4-methyl-6-tert-butylphenol); bis (3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide and bis (3,5-butylphenol)
The lubricating oil composition for an internal combustion engine according to claim 3, wherein the lubricating oil composition is at least one member selected from the group consisting of (tert-butyl-4-hydroxybenzyl) sulfide. 5. An organic molybdenum compound (B) in an amount of 0.05 to 2.0 parts by weight and a phenolic antioxidant in an amount of 0.05 to 2.0 parts by weight based on 100 parts by weight of the base oil. The lubricating oil composition for an internal combustion engine according to claim 3, wherein the lubricating oil composition comprises: