JPH0662988B2 - Lubricating base oil for internal combustion engine and composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lubricating base oil and composition for an internal combustion engine used in a nitrogen oxide gas atmosphere, more specifically a nitrogen oxide (NO _X ) gas atmosphere. The present invention relates to a lubricating base oil for an internal combustion engine, which is used in the same, and functions stably without being deteriorated by nitrogen oxide gas during the use, and a composition containing the base oil.

[Problems to be Solved by Prior Art and Invention]

In general, a part of the combustion gas in the internal combustion engine leaks into the crankcase as a blow-by gas (blow-by gas) from between the piston and the cylinder. This combustion gas contains NO _X gas in a considerably high concentration, which causes a problem that it deteriorates crankcase oil (internal combustion engine oil).

By the way, recently, an increasing number of automobiles are equipped with a reduction catalyst such as a three-way catalyst as a measure against exhaust gas regulations, and it has become possible to operate an internal combustion engine more severely (high speed / high output).

As a result, NO _X in the combustion gas that leaks into the crankcase
The gas concentration tends to increase. Further, from the viewpoint of energy saving, the weight reduction of the automobile body is promoted for the purpose of cost reduction, and accordingly, the crankcase is also downsized, and accordingly, the amount of crankcase oil (internal combustion engine oil) is also 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 In the internal combustion engine oil, the abnormal deterioration such as black sludge occurs in a short time,
The improvement is desired.

[Means for solving problems]

Therefore, the present inventor has conducted earnest studies to solve the problems of the conventional internal combustion engine oil as described above and to develop an internal combustion engine oil stable against NO _X gas. As a result, they have found that a lubricating base oil having specific properties and a mixture thereof with a phenolic antioxidant or an organic molybdenum compound can achieve the intended purpose, and have completed the present invention. .

That is, the present invention reduces the viscosity at 100 ° C. to 2 to 50 cSt and the aromatic content to 2% or less by distilling and separating crude oil and then performing refinement treatment or further deep dewaxing treatment or adjusting the synthetic oil synthesis conditions. A mineral oil and / or other synthetic oil prepared is provided as a lubricating base oil for internal combustion engines (first invention) which is a lubricating base oil used in a nitrogen oxide gas atmosphere. ) And (B) a phenolic antioxidant and used in a nitrogen oxide gas atmosphere for a lubricating oil composition for internal combustion engines (second invention), the base oils (A) and (C)
A lubricating oil composition for internal combustion engines containing an organic molybdenum compound and used in a nitrogen oxide gas atmosphere (third invention),
Furthermore, a lubricating oil composition for an internal combustion engine containing the base oil (A), (B) a phenolic antioxidant and (C) an organic molybdenum compound and used in a nitrogen oxide gas atmosphere (fourth invention) Is also provided.

The lubricating base oil of the present invention is commonly used in all of the first invention to the fourth invention, and its properties are that it is obtained by distilling and separating crude oil, followed by refining treatment or further deep dewaxing treatment, or synthetic oil. It can be obtained by adjusting the synthesis conditions.
It must be prepared to have a viscosity in the range of 2 to 50 cSt at ° C. A more preferable range is 3 to 20 cSt. If the viscosity is less than 2 cSt, the amount of evaporation loss is large, and if it exceeds 50 cSt, the power loss due to the viscous resistance is too large, which is not preferable.

Furthermore, lubricating base oil of the invention, the aromatic component content (% C _A)
Is required to be 2% or less, but a more preferable range is 1% or less. Here, when the aromatic content exceeds 2%, there is a disadvantage that the deterioration in the NO _x gas atmosphere is remarkable. Other properties of this lubricating base oil are the properties required of conventional lubricating oils for internal combustion engines, such as suitable viscosity characteristics, good oxidation stability, good competition dispersibility, and good rust prevention. It is also preferable to have anticorrosion properties and good low temperature fluidity, specifically, a viscosity index of 80 or more, a pour point of -10 ° C or less, particularly -20 ° C or less, and a total acid value of 0.1 mg.
It is a more preferable condition that it is KOH / g or less.

The lubricating base oil 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 that can be used as a lubricating base oil having the above properties of the present invention, a paraffin-based crude oil or an intermediate base crude oil is distilled under atmospheric pressure, or a residual oil of atmospheric distillation is distilled under reduced pressure. A refined oil preparation means for refining the obtained distillate oil according to a conventional method or a deep dewaxed oil preparation means for further deep dewaxing treatment after the refining is employed. The purification method at this time is not particularly limited, and various methods can be considered. Usually, (a) hydrogenation treatment, (b) dewaxing treatment (solvent dehydrogenation or hydrodewaxing), (c) solvent extraction treatment, (d) alkali distillation or sulfuric acid washing treatment, (e) clay treatment alone Or by combining them in an appropriate order. It is also effective to repeat the same processing by dividing it into a plurality of stages. For example,
Hydrotreating the distillate, or after hydrotreating,
Method of performing alkali distillation or sulfuric acid washing treatment, method of hydrotreating distillate oil, then dewaxing treatment, method of distillate oil solvent extraction treatment, then hydrotreating, distillate oil two-stage or three-stage There is a method of carrying out a stage hydrotreatment, or a method of carrying out an alkali distillation or a sulfuric acid washing treatment after that, and a method of dewaxing again to obtain a deep dewaxed oil after the treatments such as those mentioned above.

For mineral oils by the above means, 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 the present invention, the mineral oil obtained by the deep dewaxing treatment is particularly suitable as the lubricating base oil. This deep dewaxing treatment is performed by a solvent dewaxing treatment method under severe conditions, a catalytic hydrodewaxing treatment method using a zeolite catalyst, or the like.

Further, as the lubricating base oil of the present invention, the above-mentioned mineral oil, synthetic oil such as alkylbenzene, polybutene or poly (α-olefin), or a mixture thereof is used.

The first invention provides the above lubricating base oil as a lubricating oil for an internal combustion engine which is used alone in a nitrogen oxide gas atmosphere, and the base oil alone has sufficient stability against NO _X gas. Further, in the second invention, a lubricating oil composition for an internal combustion engine used in a nitrogen oxide gas atmosphere by adding (B) a phenolic antioxidant to the lubricating base oil (A) is provided. The composition shows even better stability against NO _X gas.

Here, various compounds can be used as the (B) phenolic antioxidant, and there is no particular limitation. In particular,
4,4'-Methylenebis (2,6-ditertiarybutylphenol); 4,4'-bis (2,6-ditertiarybutylphenol); 4,4'-bis (2-methyl-6-tert-butylphenol); 2,2'-methylenebis (4-ethyl-6-tertiarybutylphenol); 2,2'-methylenebis (4-methyl-6-tert-butylphenol); 4,4'-butylidenebis (3-methyl-6-tertiary) Butylphenol); 4,4'-isopropylidenebis (2,6-ditertiarybutylphenol); 2,2 '
-Methylenebis (4-methyl-6-nonylphenol); 2,2'-isobutylidenebis (4,6-dimethylphenol); 2,2'-methylenebis (4-methyl-6-cyclohexylphenol); 2,6 -Ditertiary butyl-
4-methylphenol; 2,6-ditertiary 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-ditertiarybutyl-
4-hydroxybenzyl) sulfide and the like.

The blending amount of the (B) phenolic antioxidant in the second invention varies 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.
Although not uniquely defined, usually, (B) a phenolic antioxidant is added in an amount of 0.05-2.
The ratio is 0 parts by weight, preferably 0.1 to 1.0 parts by weight.

Next, the third invention is to provide a lubricating oil composition for an internal combustion engine used in a nitrogen oxide gas atmosphere, by adding (C) an organic molybdenum compound to the lubricating base oil (A). the composition exhibits a more excellent stability against NO _X gas.

Various compounds can be used as the organic molybdenum compound (C), and there is no particular limitation. Specific examples thereof include Mo-dithiocarbamate (MoDTC) and Mo-dithiophosphate (MoDTP), which have been conventionally used as extreme pressure agents.

The blending amount of the above-mentioned (C) organomolybdenum compound in the third invention differs depending on the properties of the above-mentioned lubricating base oil which is the (A) component, the type of the organomolybdenum compound itself, etc. Usually, the proportion of the organic molybdenum compound (C) is 0.05 to 2.0 parts by weight, preferably 0.1 to 1.0 part by weight, relative to 100 parts by weight of the base oil (A).

Furthermore, in the fourth invention, for the internal combustion engine used in a nitrogen oxide gas atmosphere, by adding both the above (B) phenolic antioxidant and (C) organomolybdenum compound to this lubricating base oil (A) To provide a lubricating oil composition,
This composition exhibits particularly excellent stability against NO _X gas. Here, the blending amount of the (B) phenolic antioxidant and the (C) organomolybdenum compound is both 0.05 to 2.0 parts by weight, preferably 0.1 to 1.0 parts by weight, relative to 100 parts by weight of the (A) base oil. The ratio of parts may be used as a guide.

In the first invention, it is also effective to add various additives such as Zn-DTP, detergent dispersant, and polymer in appropriate amounts to (A) the lubricating base oil. Also, in the lubricating oil compositions of the second invention to the fourth invention, these various additives can be added.

〔Example〕

 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 1-5 and Comparative Examples 1-4 in Table 1, were subjected to NO _X deterioration test of the sample oils in the following manner. That is, iron, copper catalyst (oxidation test JIS K-2
514 specimens) in the presence of 1% nitric oxide (NO)
Gas was blown in at a rate of 6 / hr. And humidified air at a rate of 10 / hr. The temperature of the sample oil was kept at 135 ° C., and the time at which abnormal deterioration (rapid increase in acid value) began was measured. The results are shown in Table 1.

[Effects of the Invention] A lubricating base oil or a lubricating oil composition of the present invention provides a lubricating base oil or a lubricating oil composition that is used under a specific oxidizing atmosphere, that is, in a nitrogen oxide gas atmosphere. Yes, it is stable without being deteriorated even with NO _X gas, and therefore has a high NO _X gas concentration and is used for internal combustion engines at relatively high temperatures, such as gasoline engines, diesel engines, and even gas engines. That is, it is effectively used as crankcase oil of an internal combustion engine that uses natural gas, LPG (liquefied petroleum gas), cracked gas, coal cracked gas, etc. as fuel.

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Claims (7)

[Claims] 1. By distilling and separating crude oil, then refining treatment or further deep dewaxing treatment, or by adjusting synthetic oil synthesis conditions,
A mineral oil and / or synthetic oil prepared by adjusting the viscosity at 100 ° C to 2 to 50 cSt and the aromatic content to 2% or less is used as a lubricating base oil for use in a nitrogen oxide gas atmosphere. A lubricating base oil for internal combustion engines. 2. (A) The viscosity at 100 ° C. is set to 2 to 50 cSt and the aromatic content is set to 2 by refining or further deep dewaxing after distilling and separating crude oil, or adjusting the synthetic oil synthesis conditions. % Of a mineral oil and / or synthetic oil, and (B) a phenolic antioxidant, and a lubricating oil composition used in a nitrogen oxide gas atmosphere. A lubricating oil composition for an internal combustion engine. 3. The internal combustion engine according to claim 2, wherein the (B) phenolic antioxidant is contained in a proportion of 0.05 to 2.0 parts by weight with respect to 100 parts by weight of the (A) base oil. Lubricating oil composition. 4. (A) By distilling and separating crude oil and then subjecting it to a refining treatment or further deep dewaxing treatment, or by adjusting synthetic oil synthesis conditions, the viscosity at 100 ° C. is 2 to 50 cSt and the aromatic content is 2%. A base oil comprising a mineral oil and / or a synthetic oil prepared below and (C) an organic molybdenum compound,
A lubricating oil composition for an internal combustion engine, which is a lubricating oil composition used in a nitrogen oxide gas atmosphere. 5. A lubricating oil for an internal combustion engine according to claim 4, which comprises 0.05 to 2.0 parts by weight of the organic molybdenum compound (C) per 100 parts by weight of the base oil (A). Composition. 6. (A) The viscosity at 100 ° C. is 2 to 50 cSt, and the aromatic content is 2% by refining or further deep dewaxing after distilling and separating crude oil, or by adjusting synthetic oil synthesis conditions. Base oil consisting of mineral oil and / or synthetic oil prepared below, (B) phenolic antioxidant and (C)
A lubricating oil composition for an internal combustion engine, which is a lubricating oil composition containing an organic molybdenum compound and used in a nitrogen oxide gas atmosphere. 7. (A) 0.05 to 2.0 parts by weight of (B) a phenolic antioxidant and (C) with respect to 100 parts by weight of a base oil.
The lubricating oil composition for internal combustion engines according to claim 6, which contains an organic molybdenum compound in a proportion of 0.05 to 2.0 parts by weight.