JPH09104886A - Lubricating oil composition having low alkali metal content - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having good friction-decreasing effect and useful as an engine oil composition for automobile, etc., by adding an organic molybdenum compound to a base oil and decreasing the sodium content below a specific level. SOLUTION: This lubricating oil composition is composed of (A) a lubricating base oil, (B) an organic molybdenum compound such as a compound of formula I (R<1> to R<4> are each a hydrocarbon group; X<1> is O or S), a compound of formula II (R<5> to R<8> are each R<1> ; X<2> is X<1> ) and, as necessary, (C) a compound of formula III (R<9> and R<10> are each R<1> ; (a) is 0 or 1/3) or a compound of formula IV (R<11> and R<12> are each R<1> ) and has a sodium content of <=200ppm. Preferably, the component B is added in an amount of 0.005-2wt.% in terms of molybdenum based on the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a lubricating oil composition, and more specifically, it contains a molybdenum compound in a lubricating base oil,
The present invention relates to a lubricating oil composition having a sodium content reduced to 200 ppm or less.

[0002]

2. Description of the Related Art Currently, the circumstances surrounding automobiles are becoming stricter such as fuel consumption regulations and exhaust gas regulations. Behind this is the protection of resources from environmental problems such as global warming, air pollution, and acid rain, and the concern of exhaustion of limited petroleum energy. Improving fuel efficiency is currently the most effective measure against these problems. In order to reduce fuel consumption of automobiles, weight reduction of automobiles, improvement of engine, improvement of automobile itself, reduction of viscosity of engine oil to prevent friction loss in engine, addition of good friction modifier, etc. Improvement of engine oil is also an important factor.

However, at present, the engine oil has been deteriorated as the engine performance has been improved and the power output has been made worse, the oil temperature of the engine oil has risen, and the amount of oil has decreased due to the weight reduction of automobiles. It is forced to be used under more severe conditions than before. Therefore, lowering the viscosity of oil causes troubles such as wear and seizure.

Therefore, an excellent additive that solves various problems associated with the reduction of oil viscosity is desired. Generally, various additives such as friction modifiers, antioxidants, detergents, dispersants, extreme pressure agents, viscosity index improvers, pour point depressants, and antiwear agents are used in engine oils. Is maintained.
For example, in JP-A-5-508188, deterioration is caused by containing an alkali metal overbased salt of an acidic organic compound such as sodium, potassium and lithium, a dispersant, a dihydrocarbyl dithiophosphate, and an antioxidant. Lubricating compositions that reduce and suppress wear and sludge have been proposed. However, in order to solve the problem of wear and seizure,
At present, addition of an organic molybdenum compound is becoming essential.

Further, JP-A-5-279686 discloses an organic molybdenum compound, a fatty acid ester, a metal detergent (calcium sulfonate, magnesium sulfonate, calcium phenate and magnesium phenate), and ashless. Detergent / dispersant (benzylamine, benzylamine boron derivative, alkenylsuccinimide and alkenylsuccinimide boron derivative), antiwear agent [zinc dithiophosphate (ZnDTP), zinc dithiocarbamate]
It has been proposed that by blending (ZnDTC)], friction characteristics can be improved without impairing wear resistance and other characteristics.

[0006]

However, as mentioned above, a wide variety of additives are usually used in engine oils. Under such circumstances, the additives may interact with each other, and the original performance of the additives may not be exhibited.

Further, considering the current trend of fuel saving, it is important how to bring out and maintain the performance of the organic molybdenum compound. Therefore, it is necessary to study the addition of additives that bring out the performance of the organic molybdenum compound.

Therefore, an object of the present invention is to provide a novel lubricating oil composition having a better friction reducing effect.

[0009]

As a result of further studies, it was found that by reducing the alkali metal content, particularly sodium content, in the lubricating oil composition, a better friction reducing effect can be exhibited. Has been completed.

That is, the present invention is a lubricating oil composition characterized in that the lubricating base oil contains an organic molybdenum compound, and the sodium content of the lubricating oil composition is 200 ppm or less.

The present invention also provides a lubricating base oil containing at least the following general formula (1):

Embedded image (In the formula, R ^{1 to} R ⁴ represent a hydrocarbon group, X ¹ represents an oxygen atom or a sulfur atom), and a sulfurized oxymolybdenum dithiocarbamate (hereinafter, referred to as “MoDTC”)
And / or general formula (2)

Embedded image (In the formula, R ^{5 to} R ⁸ represent a hydrocarbon group, X ² represents an oxygen atom or a sulfur atom), and a sulfurized oxymolybdenum dithiophosphate (hereinafter, “MoDTP”)
And a sodium molybdenum content in the lubricating oil composition is 200 ppm or less.

Further, the lubricating oil composition of the present invention has the general formula
(3)

Embedded image (In the formula, a is 0 or 1/3, and R ⁹ and R ¹⁰ are hydrocarbon groups.) Zinc dithiophosphate (Z
nDTP) and / or general formula (4)

Embedded image Zinc dithiocarbamate (ZnDTC) represented by the formula (wherein R ¹¹ and R ¹² represent a hydrocarbon group) can be contained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the lubricating composition of the present invention,
In order to prevent the development of the original friction adjusting performance of the organic molybdenum compound, the sodium content is relative to the total amount of the lubricating oil composition.
It should be below 200 ppm, preferably below 100 ppm. The total content of alkali metals including sodium is preferably 200 ppm, preferably 100 pp.
m or less. The alkali metal referred to in the present invention is a metal lined up in Group 1 of the periodic law and includes lithium,
Refers to sodium, potassium, rubidium, cesium and francium.

In general, the case where an alkali metal such as sodium is mixed in a lubricating oil composition includes the case where an alkali metal detergent is used. Therefore, it is not preferable to use these additives in the lubricating oil composition of the present invention. Further, in the case where the alkali metal is used as a catalyst, a raw material, etc. in the separation / refining of the lubricating base oil and the synthesis process, if these are not completely removed, or in the synthesis process of the lubricating oil additive, In many cases, alkali metals or salts thereof are used as raw materials and catalysts, and there are cases where they cannot be completely removed. Examples of alkali metal compounds used as raw materials and catalysts are basic reagents such as alkali hydroxide, alkali sulfide, alkali hydrosulfide, alkali oxide, alkali alcoholate, alkali metal simple substance, alkali metal hydride, alkali aluminum hydride, and alkali boron hydride. The reducing reagents and the like can be exemplified.

In particular, since MoDTC and MoDTP usually use an alkali metal compound, especially sodium hydrosulfide, in the synthetic process thereof, when it is used in a lubricating oil composition, it is produced, for example, by the following method. Is preferred.

The method for producing MoDTC is described in, for example, Japanese Patent Publication
It is preferable to use the method described in JP-A 56-12638. In other words, by reacting molybdenum trioxide or molybdate with alkali sulfide or alkali hydrosulfide,
Those obtained by subsequently adding carbon disulfide and a secondary amine and reacting at an appropriate temperature are preferable.

The method for producing MoDTP is, for example, as follows.
The method described in JP-A-61-87690 and JP-A-61-106587 is preferable. That is, those obtained by reacting molybdenum trioxide or molybdate with alkali sulfide or alkali hydrosulfide, and then adding P ₂ S ₅ and secondary alcohol and reacting at an appropriate temperature are preferable.

The lubricating base oil used in the lubricating oil composition of the present invention may be a mineral oil or a synthetic oil. Here, the mineral oil refers to one that is separated, distilled, and refined from natural crude oil, and examples thereof include paraffin-based and naphthene-based oils, and those obtained by hydrogenating and solvent refining these.
Further, the synthetic oil is a chemically synthesized lubricating oil, and is poly-α-olefin, polyisobutylene (polybutene), diester, polyol ester, phosphoric acid ester, silicic acid ester, polyalkylene glycol, polyphenyl. Examples include ethers, silicones, fluorinated compounds and alkylbenzenes. Among these, hydrotreated and hydrorefined mineral oils and synthetic oils such as poly-α-olefins, diesters and polyol esters are preferable as the lubricating base oil for engines.

The organic molybdenum compound referred to in the present invention is
For example, in addition to MoDTC and MoDTP, those obtained by reacting molybdic acid with an amine, oxymolybdenum organophosphate, (sulfurized) oxymolybdenum xanthate, a reaction product of molybdenum and basic nitrogen, a molybdenum-based dispersant and the like can be mentioned. Among these, MoDTC, MoDTP
In regard to, the effect of sodium content is remarkably observed.

MoD used in the lubricating oil composition of the present invention
TC is a compound represented by the general formula (1), and M
oDTP is a compound represented by the general formula (2). Here, R ^{1 to} R ^{4 and} R ^{5 to} R ⁸ represent a hydrocarbon group such as an alkyl group, an alkenyl group, an alkylaryl group, a cycloalkyl group, a cycloalkenyl group and the like.

Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl. , Dodecyl, tridecyl, isotridecyl, myristyl, palmityl, stearyl, icosyl, docosyl, tetracosyl, triacontyl, 2-octyldodecyl,
2-dodecylhexadecyl, 2-tetradecyloctadecyl, monomethyl-branched-isostearyl and the like can be mentioned.

Examples of the alkenyl group include vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, oleyl and the like.

Examples of the alkylaryl group include phenyl, toluyl, xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, benzhydryl, trityl, ethylphenyl, propylphenyl,
Examples thereof include butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, α-naphthyl and β-naphthyl groups.

Examples of the cycloalkyl group and cycloalkenyl group include cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, methylcyclohexyl, methylcycloheptyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, methylcyclopentenyl, methylcyclohexenyl, methylcyclohepenyl. Examples thereof include a tenyl group.

R ^{1 to} R ⁸ may be the same or different. That is, R ^{1 to} R ^{4 and} R ^{5 to} R ⁸ may be the same or different. When R ^{1 to} R ⁴ are different from each other, it is preferable in order to make the lubricating oil composition have a long drain (long life).

Among these, R ^{1 to} R ⁴ , that is, MoD
In TC, an alkyl group having 8 to 13 carbon atoms, R ⁵ to
R ^8, ie In the MoDTP is preferably an alkyl group having 6 to 13 carbon atoms.

Further, X ¹ in the formula (1), X ² in the general formula (2), an oxygen atom or a sulfur atom, may be the same or different. If the oxygen atom is too small, the lubricity is insufficient, and if the sulfur atom is too large, the corrosiveness becomes strong. Therefore, when particularly severe lubrication conditions are required, the oxygen atom:
Sulfur atom = 1: 3 to 3: 1 is preferable.

In the present invention, MoDTC and MoD
Each TP may be used alone or in combination of two or more, and the addition amount is not particularly limited, but in order to exhibit appropriate lubricity and not to cause sludge, the amount of molybdenum should be the lubricating base oil. Is preferably 0.005
It is preferably 0.2 to 0.2% by weight, more preferably 0.01 to 0.1% by weight.

The lubricating oil composition of the present invention further comprises Z
It is preferred to add nDTP and / or ZnDTC. ZnDTP is represented by the general formula (3), and R ⁹ and R ¹⁰
Is a hydrocarbon group similar to R ^{1 to} R ⁸ . Also, ZnD
TC is represented by the general formula (4), and R ¹¹ and R ¹² are R ¹ to
It is a hydrocarbon group similar to R ⁸ . Addition of ZnDTP and / or ZnDTC is preferable in order to improve extreme pressure properties and antioxidant properties of the lubricating oil composition of the present invention.

In the ZnDTP represented by the general formula (3), R ⁹ and R ¹⁰ are hydrocarbon groups, which may be the same or different, and the same as R ^{1 to} R ⁸ described above, an alkyl group. , Alkenyl groups, alkylaryl groups and the like are preferable. Among these, an alkyl group having 3 to 14 carbon atoms is preferable.

Further, one or more kinds of ZnD to be used
It is preferred that 60% or more of R ⁹ and R ¹⁰ of TP are primary alkyl groups. The remaining 40% or less is grade 2 and / or
Alternatively, it may be a tertiary alkyl group.

In the general formula (3), a is 0 or 1 /
3 and a = 0, it is called neutral ZnDTP, and a
= 1/3, it is called basic ZnDTP.

The ZnDTP used in the present invention can be produced, for example, by the method described in JP-B-48-37251. That is, it is produced by reacting P ₂ S ₅ with a desired alcohol to produce an alkyl-substituted dithiophosphoric acid, neutralizing or basifying it with zinc oxide, and forming a zinc salt.

In the ZnDTC represented by the general formula (4), R ¹¹ and R ¹² are hydrocarbon groups and may be the same as or different from each other, and are the same as R ^{1 to} R ⁸ described above. , Alkyl groups, alkenyl groups, alkylaryl groups and the like are preferable. Among these, an alkyl group having 3 to 14 carbon atoms is preferable.

In the lubricating oil composition of the present invention, ZnDT
P and / or ZnDTC may be used alone or in combination of two or more. The addition amount of these is not particularly limited, but if the addition amount is too small, a sufficient extreme pressure effect cannot be obtained, and if the addition amount is too large, the extreme pressure property and the antioxidant property deteriorate, and further, in ZnDTP, Since it contains phosphorus, it is not preferable because it tends to poison the catalyst of the exhaust gas treatment device. Therefore, the amount of these added is preferably 0.005 to 2% by weight, more preferably 0.01 to 1% by weight, based on the lubricating base oil.

Within the scope of the object of the present invention, various known additives as required, for example, friction modifiers such as higher fatty acids, higher alcohols, amines and esters, sulfur-based, chlorine-based, phosphorus-based, organic Extreme pressure agents such as metal-based agents, antioxidants such as phenols and amines, detergents such as neutral or highly basic alkaline earth metal sulfonates, phenates and carboxylates, succinimide, benzyl Dispersants such as amines, high molecular weight poly (meth) acrylates, polyisobutylene, polystyrene, viscosity index improvers such as ethylene-propylene copolymers, styrene-isobutylene copolymers, or defoaming of esters, silicones, etc. Agents, other rust preventives, pour point depressants, amine molybdates and the like can also be added within the usual range of use.

The lubricating oil composition of the present invention comprises a vehicle engine including an automobile, a two-cycle engine, an aircraft engine, a marine engine and a locomotive engine (these engines may be gasoline, diesel, gas or turbine). ) And the like for internal combustion engines, automatic transmission liquids, transaxle lubricants, gear lubricants, metalworking lubricants, etc.

[0038]

The present invention will be described in detail below with reference to examples. The components used in the lubricating oil compositions of the product of the present invention and the comparative product will be described below. Lubricating base oil: A mineral oil-based high VI oil obtained by hydrocracking a mineral oil obtained from a crude oil. Kinematic viscosity is 100 ° C
Then 4.1 cSt, VI = 126. Sodium content 10p
pm or less.

Mo compound 1: In the general formula (1), R ¹
MoDTC in which R ⁴ = 2-ethylhexyl group and X ¹ = S / O = 2.2. Sodium content 10ppm or less. Mo compound 2: In the general formula (1), R ^{1 to} R ⁴ = 2-ethylhexyl group: isotridecyl group = 1: 1, X ¹ = S
MoDTC with /O=2.2. Sodium content 10p
pm or less Mo compound 3: MoDT in which R ^{5 to} R ⁸ = 2-ethylhexyl group and X ² = S / O = 2.2 in the general formula (2)
P. Sodium content 10ppm or less.

Detergent 1: Calcium sulfonate. Sodium content 10ppm or less. Detergent 2: Magnesium sulfonate. Sodium content 10ppm or less. Detergent 3: Calcium salicylate. Sodium content 1
0 ppm or less. Detergent 4: Sodium phenate. Sodium content 1
0.5% by weight.

ZnDTP: In the general formula (3), R ⁹ and R ¹⁰ = 2-ethylhexyl group, neutral salt: basic salt = 5
5:45 (molar ratio). Sodium content 10ppm or less. ZnDTC: In the general formula (4), R ¹¹ and R ¹² are 2-
Ethylhexyl group. Sodium content 10ppm or less.

The sodium content of each of the above components was measured by the ICP method after ashing.

Lubricating oil compositions of the present invention and comparative products were obtained by blending the above components in the proportions shown in the table below. In addition, among the numerical values in the table, the Mo compound is molybdenum weight% with respect to the lubricating base oil, and the others are weight%.

The lubricating oil composition obtained above was subjected to a friction coefficient measurement test by the following method: Friction coefficient measurement test The friction coefficient measurement test was carried out using an SRV measuring tester under the following conditions. <Conditions> Line contact: The test conditions were cylinder-on-plate line contact conditions. That is, upper cylinder- (φ15 × 22mm)
Was set perpendicularly to the sliding direction on a plate (φ24 × 6.85 mm), reciprocally oscillated, and after 7 minutes, the friction coefficient was measured. Both were made of SUJ-2. Load: 200 N Temperature: 80 ° C. Measurement time: 15 minutes Amplitude: 1 mm Cycle: 50 Hz The measurement results obtained are also shown in the table below.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

The effect of the present invention is to provide a novel lubricating oil composition having a good friction reducing effect.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C10M 135: 18) C10N 10:04 10:12 30:06 40:25 (72) Inventor Yoko Saito Asahi Denka Kogyo Co., Ltd. 7 2-35 Higashiohisa, Arakawa-ku, Tokyo

Claims (7)

[Claims] 1. A lubricating base oil containing an organic molybdenum compound, wherein the lubricating oil composition has a sodium content of 200 ppm.
A lubricating oil composition comprising: 2. A lubricating base oil having the following general formula (1): (Wherein R ^{1 to} R ⁴ represent a hydrocarbon group and X ¹ represents an oxygen atom or a sulfur atom), and / or a general formula of sulfurized oxymolybdenum dithiocarbamate.
(2) [Chemical 2] (Wherein R ^{5 to} R ⁸ represent a hydrocarbon group, and X ² represents an oxygen atom or a sulfur atom), and one or more selected from the group consisting of sulfurized oxymolybdenum dithiophosphates. Containing an organic molybdenum compound of
A lubricating oil composition, wherein the sodium content in the lubricating oil composition is 200 ppm or less. 3. The lubricating oil composition according to claim 1, wherein the total content of alkali metals including sodium is 200 ppm or less. 4. The addition amount of sulfurized oxymolybdenum dithiocarbamate and / or sulfurized oxymolybdenum dithiophosphate is 0.005 to 2% by weight in terms of molybdenum based on the lubricating base oil. The lubricating oil composition according to item 1. 5. The lubricating oil composition further comprises a compound represented by the general formula (3): (In the formula, a is 0 or 1/3, R ⁹ and R ¹⁰ are hydrocarbon groups) and / or zinc dithiophosphate represented by the general formula (4) The lubricating oil composition according to any one of claims 1 to 4, containing zinc dithiocarbamate represented by the formula: wherein R ¹¹ and R ¹² represent a hydrocarbon group. 6. The lubricating oil composition according to claim 5, wherein the amount of zinc dithiophosphate and / or zinc dithiocarbamate added is 0.005 to 2% by weight based on the lubricating base oil. 7. An engine oil composition comprising the lubricating oil composition according to any one of claims 1 to 6.