JPH1135962A - Lubricating oil composition - Google Patents

Abstract

(57) Abstract: for GHP, for gasoline engines, and allows the longevity of engine oil, such as diesel engines, to provide a resistance to NO _X stability and lubricating oil composition excellent in oxidative stability . SOLUTION: It contains a base oil, (A-1) a phosphorus-containing phenolic antioxidant, (A-2) a phosphorus-free phenolic antioxidant, and (A-3) an amine-based antioxidant. It is a lubricating oil composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to lubricating oil compositions, particularly to lubricating oil composition suitably used as an engine oil resistant NO _X and oxidative stability to the excellent long life.

[0002]

The maintenance cycle of various engines such as a gasoline engine, a diesel engine, and an engine for a gas heat pump is greatly affected by the life of the lubricating oil, similarly to the hardware aspects. In particular, the gas heat pump (GHP) system has a disadvantage that the maintenance cycle is short from the beginning of development because the used engine oil deteriorates quickly. Therefore, in this field, suppressing the deterioration of the lubricating oil and extending the service life leads to extending the maintenance cycle, which in turn leads to a reduction in maintenance costs. From the viewpoint of extending the maintenance cycle, various studies have been made on extending the life of the hardware surface of each component of the GHP system, and certain results have been obtained. On the other hand, although also considered life extension of the lubricating oil have been made, the structure of the GHP, for GHP lubricating oil has a high combustion temperature, the higher the concentration of NO _X in the blowby gas, this because NO _X oxide There is a problem that deterioration is easily caused and deterioration is easily caused. In addition, there is a problem that the combustion temperature is high and it is susceptible to oxidative deterioration due to oxygen.As a result, the results of the study on the hardware side have not been obtained, and the service life of the lubricating oil has yet to extend the maintenance cycle. It was the fact that it was obstructing. The present invention has been made under such circumstances. That is, the present invention aims to provide a GHP for, for gasoline engines, and allows the life extension of the various lubricating oils such as diesel engines, resistant NO _X and oxidative stability to the excellent lubricating oil composition Is what you do.

[0003]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a specific antioxidant containing a phosphorus-containing phenolic antioxidant is combined with a base oil. Accordingly, to allow the life extension of the lubricating oil, have found that it is possible to improve the resistance to NO _X and oxidative stability. The present invention has been completed based on such findings. That is, the present invention provides a base oil,
(A-1) a phosphorus-containing phenolic antioxidant, (A-
2) A lubricating oil composition containing a phosphorus-free phenolic antioxidant and (A-3) an amine antioxidant.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The lubricating oil composition of the present invention comprises a base oil, (A-1) a phosphorus-containing phenolic antioxidant, (A-2) a phenolic antioxidant containing no phosphorus, and (A-3) an amine-based oxidation. It contains an inhibitor. As the base oil of the lubricating oil composition of the present invention, any of mineral oil and synthetic oil can be used without any particular limitation, but those having a kinematic viscosity at 100 ° C. in the range of ² to 50 mm ² / sec are generally used. Is done. When the kinematic viscosity is within the above range, more favorable results can be obtained in terms of wear resistance and engine startability. In the present invention, the base oil is N-resistant.
Ox stability, in terms of oxidation stability, highly refined base oil is preferably used, except such as aromatic content, specifically% C _A of 10% or less, preferably 5% or less, more preferably 1%
The following are preferably used: % If C _A is more than the above range resistance NOx stability, it may oxidative stability poor undesirably. The above% C _A is a ring analysis value based on the ndM method.

[0005] Examples of the mineral oil include paraffinic mineral oil, intermediate mineral oil, and naphthenic mineral oil obtained by ordinary refining methods such as solvent refining and hydrogenation refining. Examples of the synthetic oil include poly-α-olefins (including both homopolymers and copolymers) such as poly-α-olefins and ethylene propylene copolymers;
Examples include various esters such as polyol esters, dibasic acid esters, and phosphoric acid esters, various ethers such as polyphenyl ethers, alkylbenzene, and alkylnaphthalene. In the present invention, synthetic oils, particularly poly-α-olefins and esters, are preferably used as the base oil from the viewpoint of oxidation stability. In the present invention, one of the above base oils may be used alone, or two or more may be used in combination.

[0006] The phosphorus-containing phenolic antioxidant as the component (A-1) is used from the viewpoint of improving oxidative stability. Various things are available,
Preferably, a compound represented by the following general formula (I) is used.

[0007]

Embedded image

Wherein A ¹ and R ^{1 to} R ⁴ each represent a hydrocarbon group, and R ¹ and R ² and R ³ and R ⁴ may be the same or different. In the general formula (I), the hydrocarbon group represented by A ¹ is preferably an alkylene group having 1 to 8 carbon atoms, such as a methylene group, an ethylene group, and a propylene group. The hydrocarbon group represented by each of R ^{1 to} R ⁴ includes an alkyl group having 1 to 24 carbon atoms,
An alkyl group of 8 is preferably used, and specific examples include a methyl group, an ethyl group, a propyl group, and a tert-butyl group. Specific examples of the phosphorus-containing phenolic antioxidant in the present invention include the following compounds (A-1-
1) can be used.

[0009]

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The above phosphorus-containing phenolic antioxidant is contained in the lubricating oil composition of the present invention in an amount of 0.05 to 5% by weight. When the content is less than 0.05% by weight, the oxidation stability is hardly improved, and when the content is more than 5% by weight, it tends to deteriorate the oxidation stability, which is not preferable. From this point,
More preferably, the content is in the range of 0.05 to 1% by weight.

The lubricating oil composition of the present invention contains a phosphorus-free phenolic antioxidant as component (A-2) from the viewpoint of improving oxidation stability. As such a phosphorus-free phenolic antioxidant, any of various known non-phosphorous phenolic antioxidants can be used, but a phenolic antioxidant containing an ester group and sulfur and It is preferable to use other non-phosphorus phenolic antioxidants. As the phenolic antioxidant containing an ester group and sulfur, various conventionally known phenolic antioxidants can be used.
The compound represented by the following general formula (II) can be used.

[0012]

Embedded image (Wherein A ² , A ³ , R ⁵ , R ⁶ and R ⁷ are each a hydrocarbon group, or

[0013]

Embedded image Represents Here, A ² , A ³ , R ⁵ and R ⁶ are the same as above. )

In the general formula (II), A ² and A ³
Is an alkylene group having 1 to 3 carbon atoms, specifically, a methylene group, an ethylene group,
Examples of the hydrocarbon group represented by each of R ^{5 to} R ⁷ include an alkyl group having 1 to 24 carbon atoms,
Preferably an alkyl group having 1 to 8 carbon atoms, specifically, t
tert-butyl, methyl, ethyl, propyl and the like. Here, each of R ^{5 to} R ⁷ may be the same or different. As the phenolic antioxidant containing an ester group and sulfur, specifically, the following compound (A-2-1) can be used.

[0015]

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As other phenolic antioxidants, compounds represented by the following formulas (III) to (V) can be used.

[0017]

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Wherein A ⁴ , A ⁵ and R ⁸ -R ¹⁷ each represent a hydrocarbon group having 1 to 24 carbon atoms. In each of the above general formulas (III) to (V), A ⁴ and A
^The hydrocarbon group represented by each of ⁵ preferably includes an alkylene group having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, and a propylene group. Further, as the hydrocarbon group having 1 to 24 carbon atoms represented by each of R ^{8 to} R ¹⁷ ,
Specific examples include a tert-butyl group, a methyl group, an ethyl group, and an isopropyl group. Here, R ^{8 to} R
¹⁰ may be the same or different. Also, R ¹¹
To R ¹⁴ may be the same or different. Furthermore,
R ^{15 to} R ¹⁷ may be the same or different. In the present invention, among the above compounds, compounds represented by the general formula (IV) are particularly preferably used. As the other phenolic antioxidants, specifically, the following compounds (A-2-2) to (A-2-4) can be used.

[0019]

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The phosphorus-free phenolic antioxidant is contained in the lubricating oil composition of the present invention in an amount of 0.05 to 5% by weight.
Contained. When the content is less than 0.05% by weight, the oxidation stability is hardly improved. When the content is more than 5% by weight, the oxidation stability is adversely affected, which is not preferable. In this respect, the content is more preferably in the range of 0.1 to 3% by weight.

The lubricating oil composition of the present invention further comprises (A-
3) An amine antioxidant is contained as a component from the viewpoint of improving oxidation stability. As such an amine antioxidant, any of various known ones can be used,
Preferably, compounds represented by the following general formulas (VI) and (VII) can be used.

[0022]

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Wherein R ¹⁸ -R ²³ are each a hydrogen atom,
Represents a hydrocarbon group having 1 to 24 carbon atoms. As the hydrocarbon group represented by each of the general formulas (VI) and (VII), a hydrocarbon group having 1 to 24 carbon atoms, preferably a hydrocarbon group having 1 to 12 carbon atoms is used. Has t
tert-butyl, octyl, nonyl, 1,1,
Examples include a 3,3-tetramethylbutyl group. Here, R ^{19 to} R ²³ may be the same or different. As the amine antioxidant in the present invention, it is particularly preferable to use a combination of the compound represented by the general formula (VI) and the compound represented by the general formula (VII). Specifically, the following compounds (A-3-1) to (A-
3-3) can be used.

[0024]

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The above-mentioned amine antioxidant is contained in the lubricating oil composition of the present invention in an amount of 0.05 to 10% by weight. Content
If it is less than 0.05% by weight, the oxidation stability hardly improves, and
If the amount is more than 10% by weight, the oxidative stability may be deteriorated, which is not preferable. From this point, the content is 0.1.
More preferably, it is in the range of ３3% by weight.

The lubricating oil composition of the present invention exhibits excellent effects of the present invention by using the above components (A-1) to (A-3) in combination with a base oil. In particular, the compound of the above general formula (I) as the component (A-1), the compound of the above general formula (II) or the compound of the general formula (IV) as the component (A-2), and (A-3) Particularly excellent effects can be obtained by using a combination of the compound of the general formula (VI) and the compound of the general formula (VII) as a component.

The lubricating oil composition of the present invention may further contain, in addition to the above components, an ashless dispersant, a metal additive having an antioxidant effect and an antiwear effect, or a metal detergent, if desired. They can be used in combination. The ashless dispersant is used for dissolving (dispersing) sludge generated in the engine oil during use. As such an ashless dispersant, alkenyl succinimides are preferable. In particular, those containing boron-containing alkenyl succinimides or a combination of these and boron-free alkenyl succinimides are preferably used. Such an ashless dispersant is contained in the lubricating oil composition of the present invention in an amount of 0.1 to 10% by weight. If the content is less than 0.1% by weight, the sludge dispersing ability is insufficient, and
When the amount exceeds 0% by weight, there is no effect just to meet the added amount. From this viewpoint, the content is more preferably in the range of 1 to 7% by weight.

Metal additives having an antioxidant effect and an antiwear effect are used for the purpose of preventing the wear of the valve train and the abrasion of the sealing liner and the piston ring. Any compound can be used as long as the compound also has a preventive action.
Zinc dithiophosphate (ZnDTP) is preferably used. Such additives are present in the lubricating oil composition of the present invention.
0.1 to 3% by weight is contained. If the content is less than 0.1% by weight, the effect of preventing abrasion decreases, and if it exceeds 3% by weight, the effect does not increase with respect to the amount added. In this respect, the content is more preferably in the range of 0.1 to 2% by weight.

Metallic detergents are used for the purpose of keeping pistons, cylinders, etc. clean. For example, (a) calcium (C)
a) or magnesium (Mg) salicylate,
(B) Metal salicylates, phenates and sulfonates such as (P) Ca or Mg phenates and (C) Ca or Mg sulfonates can be used. These can be used alone or in combination of two or more. In the present invention, it is particularly preferable to use the salicylate of (a) and the phenate of (b) in combination. These metal-based detergents are contained in the lubricating oil composition of the present invention in an amount of 500 to 4000 ppm by weight in terms of the amount of metal. If the content is less than 500 ppm by weight, the cleanliness is insufficient and 400
If the content exceeds 0 ppm by weight, a large amount of combustion residue remains in the combustion chamber, shortening the life of the engine. In this respect, the content is more preferably in the range of 800 to 3500 ppm by weight in terms of metal.

It is also optional to appropriately add an agent such as an extreme pressure agent, a viscosity index improver, a pour point depressant, a rust inhibitor, a metal corrosion inhibitor, a surfactant and an antifoaming agent. The lubricating oil composition of the present invention can be widely applied to various engine oils such as a GPH engine, a gasoline engine, a diesel engine and the like, and particularly excellent effects can be obtained by applying the composition to a GPH engine.

[0031]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Examples 1 to 7 and Comparative Examples 1 to 8 Lubricating oils having the compositions and blending ratios (% by weight) shown in Table 1 were prepared, and the following performances were evaluated for each of them. The results are shown in Table 1.

[Evaluation Performance] (1) IP-ISOT (Induction Period-Lubricating Oil Oxidation Stability Test for Internal Combustion Engine) The test was carried out using the apparatus and test method described in Japanese Patent Application No. 6-63217. Take 250 milliliters of sample into a container,
3 liters / hour of oxygen blown into coiled copper
Maintained at 175.0 ° C. with iron catalyst. In this state, the oxidation life (hr) of the sample is evaluated based on the time until the sample temperature rises sharply. The other conditions are as follows: ISOT
(Lubricating oil oxidation stability test for internal combustion engines, JIS K-25
Same as 14). (2) TFOUT (Thin-film Oxygen Uptake Test) 1.5 g of a sample was placed in a 6.3 kg / cm ² pressurized oxygen atmosphere under the conditions of 0.03 g of water, 0.06 g of a metal catalyst, and 0.06 g of a fuel catalyst.
At the same time. In this state, the oxidation life (min) of the sample is evaluated based on the time until the sealed oxygen pressure drops rapidly. Other conditions are ASTM
Same as D-4742.

[0033]

[Table 1]

[Table 2]

* 1 Base oil 1: A mixed oil of 100N (100N neutral oil) and 150N, kinematic viscosity at 100 ° C. 5.
2 mm ² / sec,% CA 7% * 2 Base oil 2: mixed oil of 100N (100N neutral oil) and 150N, kinematic viscosity at 100 ° C 5.1 mm ² / s
ec,% CA 0.2% or less * 3 Base oil 3: 500N (500N neutral oil),
Kinematic viscosity at 100 ° C 11 mm ² / sec,% CA 0.2%
* 4 Base oil 4: Mixed oil of 100N (100N neutral oil) and 150N, kinematic viscosity at 100 ° C 5.2 mm ² / s
ec,% CA 2% * 5 Phosphorus-containing phenol: Compound (A-1-1) * 6 Hindered phenol 1: Compound (A-2-
1) * 7 Hindered phenol 2: Compound (A-2-
3) * 8 Dialkyldiphenylamine: Compound (A-3)
-3) * 9 Alkylated phenylnaphthylamine compound (A
-3-2) * 10 Metallic detergent: Calcium detergent, base number 2
50 mg KOH / g * 11 Ashless dispersant: alkenyl succinimide (boron-containing alkenyl succinimide, boron-free alkenyl succinimide) * 12 ZnDTP: zinc dialkyldithiophosphate * 13 VII (viscosity index improver): olefin Copolymer PPD (Pour Point Depressant): Polymethacrylate

[0035]

As described in detail above, the lubricating oil composition of the present invention makes it possible to extend the life of the lubricating oil,
A lubricating oil composition having excellent _X stability and oxidation stability can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10M 129: 10 129: 14 129: 76 133: 12 133: 16) (C10M 141/12 137: 12 135: 26 129: 10 129) : 14 129: 76 133: 12 139: 00) C10N 30:04 30:08 30:10 40:25

Claims (7)

[Claims] 1. A base oil comprising (A-1) a phosphorus-containing phenolic antioxidant, (A-2) a phosphorus-free phenolic antioxidant, and (A-3) an amine-based antioxidant. Lubricating oil composition. 2. (A-1) Phosphorus-containing phenol-based antioxidant
The inhibitor is a compound represented by the following general formula (I)
The lubricating oil composition according to claim 1, characterized in that: Embedded image[Where A¹, R¹~ R^FourEach represents a hydrocarbon group,
R¹And R^TwoAnd R^ThreeAnd R ^FourAre the same but different
It may be. ] 3. (A-2) The phenolic antioxidant containing no phosphorus is a phenolic antioxidant containing an ester group and sulfur and / or another phenolic antioxidant. The lubricating oil composition according to claim 1. 4. The method according to claim 1, wherein (A-3) the amine antioxidant is a diphenylamine antioxidant and / or a phenylnaphthylamine antioxidant.
4. The lubricating oil composition according to any one of 3. 5. The lubricating oil composition according to claim 1, further comprising an ashless dispersant. 6. The lubricating oil composition according to claim 5, wherein the ashless dispersant comprises a boron-containing alkenyl succinimide and / or a boron-free alkenyl succinimide. . 7. A lubricating oil oil composition according to any one of claims 1 to 6% C _A of base oil is equal to or less than 10%.