JP2000256690A - Lubricating oil composition for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating oil composition for internal combustion engines suitable as a diesel engine oil composition which has a low ash content, which has reduced effects on a particulate trap and an oxidation catalyst and which has enough oxidation stabilizing properties and anti-coking properties. SOLUTION: A lubricating oil composition is obtained by blending (A) 0.08 wt.% or more in terms of the nitrogen content in the composition of an ashless dispersant, (B) 0.5 wt.% or more of a phenol-based ashless antioxidant, (C) a metal-based cleaning agent in an amount to give a calcium content of 0.08-0.14 wt.% in the composition and (D) 0.7 wt.% or less of a sulfuric acid ash content based on the total weight of the composition, with a lubricating oil base oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating oil composition for an internal combustion engine. More specifically, the present invention relates to a lubricating oil composition for an internal combustion engine which has a small amount of calcium and sulfated ash, does not impair the performance of an exhaust gas aftertreatment device, and has excellent oxidation stability and coking resistance.

[0002]

2. Description of the Related Art From the viewpoint of controlling air pollution, it is required to reduce nitrogen oxides (NOx) and particulate emissions (particulates) in exhaust gas from diesel engines. Development of after-treatment devices for exhaust gas has been promoted. However, when a diesel engine oil of API (American Petroleum Institute) CD class or higher conventionally used is used for an engine equipped with these after-treatment devices, the combustion product of the metal-based detergent is high due to the high ash content. The problem of clogging by certain metal oxides and acid neutralization products arises. Therefore, low ash differentiation (reduction of metal-based detergents) is necessary. However, reduction of metal-based detergents causes not only a decrease in cleanliness but also an early deterioration of the base oil due to a decrease in oxidative stability. Worsen. Since the decrease in coking resistance causes the formation of deposits in the combustion chamber, which is the cause of particulates,
Inadvertent low ash differentiation rather degrades the performance of the exhaust gas aftertreatment device.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, the present invention has a low ash content, has little effect on a particulate trap and an oxidation catalyst, and has a sufficient oxidation stability performance.
An object of the present invention is to provide a lubricating oil composition for an internal combustion engine that is suitable as a diesel engine oil composition having anti-coking performance.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to develop a lubricating oil composition for an internal combustion engine having the above-mentioned preferable properties, and as a result, have identified a less than usual amount of a metallic detergent. It has been found that a lubricating oil composition containing an ashless antioxidant and an ashless dispersant in an amount equal to or more than the above amounts and having calcium and sulfated ash contents within a predetermined range can achieve the object.

That is, the present invention provides: Based on the total weight of the composition with respect to the lubricating base oil, (A) 0.08% by weight or more of an ashless dispersant as a nitrogen content in the composition, and (B) a phenolic ashless antioxidant. 5
% By weight, and (C) a metal-based detergent is blended in such a proportion that the calcium content in the composition is 0.08 to 0.14% by weight. Weight% or less of a lubricating oil composition for an internal combustion engine,

[0006] 2. The lubricating oil composition for an internal combustion engine according to the above 1, wherein the component (C) has a base number (perchloric acid method) of 0 to 400 mgKOH / g calcium sulfonate and / or 0 to 300 mgKOH / g calcium finate. It is.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The base oil in the lubricating oil composition of the present invention is not particularly limited as long as it is a mineral oil, a synthetic oil, or a mixed oil of both.
A base oil whose kinematic viscosity at 0 ° C. is adjusted to a range of 8 to 15 mm ² / s is preferred.

The succinimide-based ashless dispersant as the component (A) is added together with a metal-based detergent for the purpose of controlling the cohesion of solid impurities.

[0009] The amount of the succinimide-based ashless dispersant is preferably 0.08% by weight or more as a nitrogen content in the lubricating oil composition in order to compensate for the lack of clean dispersing performance due to low ash differentiation. The succinimide-based ashless dispersant that can be used is not particularly limited, but is preferably a mono-type succinimide-based ashless dispersant and / or a bis-type succinimide-based ashless dispersant.

The phenolic ashless antioxidant of component (B) is 2,6-di-t-butylphenol, 2,6-
Di-t-butyl-4-methylphenol, 2,6-di-
t-butyl-4-ethylphenol, 4,4′-methylenebis (2,6-di-t-butylphenol), 4,
4'-bis (2,6-di-t-butylphenol),
2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-
Oligomers of 6,4-t-butylphenol), 4,4'-methylenebis (t-butylphenol) and mixtures thereof.

The amount of the phenolic antioxidant to be added is preferably 0.5% by weight or more based on the total amount of the lubricating oil composition, and if it is less than 0.5% by weight, the oxidation stability is significantly reduced. The metal detergent as the component (C) has a base number [JI
SK-2501 (perchloric acid method)] is 0 to 400 mgK
OH / g calcium sulfonate and / or 0-300 mg KOH / g calcium finate are used. The amount of calcium added is 0.08 to 0.14% by weight based on the total amount of the lubricating oil composition. If the Ca content is less than 0.08, the acid neutralization performance is insufficient, the lubricating oil is likely to deteriorate, and the cleanliness is reduced. 0.14
Exceeding the weight% is not preferable because the ash content increases and causes clogging of the exhaust gas aftertreatment device.

In the present invention, the amount of sulfated ash is 0.7% by weight.
Exceeding the ash content is not preferred because the ash content increases and causes clogging of the exhaust gas aftertreatment device.

In the lubricating oil composition of the present invention, if necessary, an antioxidant and antiwear agent, a viscosity index improver, a pour point depressant, a defoamer, as long as the object of the present invention is not impaired. , A friction modifier and the like can be blended according to the application. Among these additives, antioxidants and antiwear agents, viscosity index improvers and pour point improvers are preferably used. As an antioxidant and antiwear agent, zinc dithiophosphate (ZnDT
P) is preferred, and primary alkyl group type ZnDTP
And / or a secondary alkyl group type ZnDTP is preferred.

As the viscosity index improver, for example, polymethacrylate, dispersion type polymethacrylate, olefin copolymer, dispersion type olefin copolymer, etc., and as the pour point depressant, for example, polymethacrylate, etc. can give.

[0015]

The present invention will now be illustrated by way of examples. A lubricating oil composition was prepared by blending each type of component shown in Table 1 with the base oil (mixture of 250 neutral oil and 500 neutral oil) based on the total weight of the composition.
Here, Comparative Example 2 is a CD determined by the American Petroleum Institute (API).
This is a lubricating oil composition corresponding to the standard. Comparative Example 1 is a composition having a reduced ash content by reducing the amount of the metal-based detergent in Comparative Example 2. IS for these lubricating oil compositions
OT (lubricant oxidation stability test for internal combustion engines) [JIS K
-2514], an oxidation test was conducted at 165.5 ° C for 72 hours. The kinematic viscosity (J
IS K-2283) and carbon residue (JIS K
-2270) and a panel coking test [Federal Test Method 791B].
-3462 compliant] panel temperature 300 ° C, oil temperature 10
The coking resistance evaluation test was performed at 0 ° C. for 3 hours. The evaluation of the coking resistance was evaluated by the amount (mg) of carbon deposited on the aluminum panel.

In Comparative Example 3, the American Petroleum Institute (API)
Is a lubricating oil composition corresponding to the CC standard specified by
It has a low calcium content compared to diesel engine oil. For Example 1 and Comparative Example 3, a real vehicle running test (city driving) was performed using a large bus equipped with a particulate trap, and the amount of sediment in the trap after running for a certain period of time (for 6 months) with the same vehicle was measured. It was measured. In addition,
The running distance is 23,000 km in Example 1 and 17,350 km in Comparative Example 3.

[0017]

[Table 1]

Example 1 The increase in kinematic viscosity after the oxidation test was 3.42 mm ² / s, and the increase in the residual carbon content was 2.14% by weight. The amount of carbon deposited in the panel coking test after the oxidation test was 2 mg. Incidentally, the trap deposit amount after the actual vehicle test was reduced by 47% as compared with Comparative Example 3.

Comparative Example 1 The increase in kinematic viscosity after the oxidation test was 17.01 mm ² / s, and the increase in residual carbon content was 3.66% by weight. Further, the carbon deposition amount in the panel coking test after the oxidation test was 200 mg.

Comparative Example 2 The increase in the kinematic viscosity after the oxidation test was 8.91 mm ² / s, and the increase in the residual carbon content was 3.08% by weight. The amount of carbon deposited in the panel coking test after the oxidation test was 1 mg.

Comparative Example 3 The trap deposit after the actual vehicle test was mainly composed of calcium. In addition, the deposit amount in this example was set to 100.

[0022]

The lubricating oil composition for an internal combustion engine according to the present invention has a reduced ash content and a low ash differentiation and anti-coking resistance by adding a phenolic antioxidant and an ashless dispersant in a specific amount or more. The effect on the exhaust gas post-treatment device is reduced from both aspects of improvement in the performance.

The oil of the present invention is particularly effective for a diesel engine equipped with a particulate trap, and its performance was able to be confirmed in an actual vehicle running test.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10N 30:04 40:25 (72) Inventor Miki Sasaki 4-19-19 Kami Aso, Aso-ku, Kawasaki City, Kanagawa Prefecture 406 F term (reference) 4H104 BB05C BF03C DA02A DB06C DB07C EA21C EA22C EB02 FA02 LA02 LA05 PA41

Claims (2)

[Claims] Claims: 1. Based on the total weight of the composition relative to the lubricating base oil,
(A) An ashless dispersant having a nitrogen content of 0.1% in the composition.
08% by weight or more, (B) a phenolic ashless antioxidant 0.5% by weight or more, and (C) a metal detergent having a calcium content of 0.08 to 0.14% by weight in the composition. (D) a lubricating oil composition for an internal combustion engine having a sulfated ash content of 0.7% by weight or less. 2. The internal combustion engine according to claim 1, wherein the component (C) is a calcium sulfonate having a base number (perchloric acid method) of 0 to 400 mg KOH / g and / or a calcium finate of 0 to 300 mg KOH / g. Lubricating oil composition.