JPH07150173A - Lubricating oil composition - Google Patents

Abstract

PURPOSE:To obtain a lubricating oil composition which is excellent in frictional properties and abrasion resistance and with which a low coefficient of friction can be maintained in not only severe frictional conditions but mild ones. CONSTITUTION:This composition comprises 100 pts.wt. base oil, 0.005-0.2 pts.wt. molybdenum ingredient (a) in terms of molybdenum amount, and 0.1-2.0 pts.wt. alkanolamine or alkanolamide, the ingredient (a) comprising 40-100wt.% hydroxymolybdenum dithiocarbamate sulfide having a 12-22C alkyl group and 60-0wt.% hydroxymolybdenum dithiocarbamate sulfide having a 2-11C alkyl group.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel lubricating oil composition, and more specifically, it has excellent friction characteristics such as a low friction coefficient even under different friction conditions, and has an industrial lubricating oil and an automobile lubricating oil. In particular, the present invention relates to a lubricating oil composition suitable as a lubricating oil for internal combustion engines of automobiles.

[0002]

2. Description of the Related Art Conventionally, lubricating oils have been used in internal combustion engines, drivetrain devices such as automatic transmissions, shock absorbers, power steering systems, gears, etc. in order to ensure smooth operation. In particular, lubricating oil for internal combustion engines (engine oil) mainly lubricates various sliding parts, such as piston rings and cylinder liners, bearings for crankshafts and connecting rods (connecting rods), valve trains including cams and valve lifters, etc. It functions to cool the engine, cleanly disperse combustion products, and prevent rust and corrosion. As described above, lubricating oils for internal combustion engines are required to have various performances, and in recent years, high performances have been required as the performances, output power, and operating conditions of internal combustion engines have become more severe. . Therefore,
In order to satisfy such required performance, the lubricating oil for internal combustion engine may be, for example, an antiwear agent, a metal detergent, an ashless dispersant,
Various additives such as antioxidants are blended. As a basic function of a lubricating oil for an internal combustion engine, it is important to operate the engine smoothly under all conditions to prevent wear and seizure. Although most of the engine lubrication part is in a liquid lubrication state, boundary lubrication is likely to occur at the valve operating system and the top and bottom dead center of the piston, and the wear prevention property under such boundary lubrication is generally zinc dithiophosphate ( ZnDTP)
And zinc dithiocarbamate (ZnDTC). By the way, in an internal combustion engine, energy loss is large in a friction portion where lubricating oil is involved.
As a measure to reduce friction loss and fuel consumption, a friction modifier (F
M: Friction modifier) is added to the lubricating oil. As the friction modifier, for example, an extreme pressure agent such as a molybdenum compound or a phosphoric acid ester, or a compound belonging to an oily agent such as a fatty acid ester or an alkylamine is generally used. However, if an antiwear agent and a friction modifier are used together, competitive adsorption on the metal surface leads to an unfavorable situation in which the functions of both are not fully exhibited. That is, ZnDTP and ZnDTC prevent wear due to metal-metal contact by forming a protective film on the metal surface, but the friction modifier also adsorbs to the metal surface and reacts with it, or generates polymer on the metal surface. Forms a low-friction surface coating, and exerts the effect of reducing friction. Therefore, ZnDTP or Zn should be used as the lubricating oil.
When DTC and a friction modifier are added, the amount of ZnDTP or ZnDTC adsorbed on the metal surface is reduced due to the competitive adsorption of both, and the wear resistance is deteriorated. In some cases, a sufficient friction reducing effect cannot be obtained. On the other hand, ZnDTP and ZnDTC
Can interact with certain detergent dispersants and compromise wear resistance. In addition, other additives such as detergent dispersants may also affect the effect of friction modifiers. Therefore, sufficient consideration needs to be given to the selection of other additives such as a detergent dispersant and the concentration of such additives. Further, in the internal combustion engine lubricating oil, the friction characteristic is an important lubricating performance for reducing fuel consumption. Since the inside of the engine is lubricated under various friction conditions such as temperature and contact pressure, it is required to keep the friction coefficient low under these friction conditions. However, the conventional friction modifier has insufficient friction characteristics under different friction conditions. Conventionally, as a molybdenum-based friction modifier,
Sulfurized oxymolybdenum dithiocarbamate (MoDTC) having an alkyl group is mainly used, but the sulfurized oxymolybdenum dithiocarbamate having a low carbon number of the alkyl group has a high thermal decomposition temperature and is considerably strict to act as a friction modifier. Since lubrication conditions are required and the alkyl group is short, so-called oiliness is not expected, and even when the lubrication conditions are mild, oil film breakage easily occurs. In addition, although MoDTC having a large number of carbon atoms in the alkyl group may be used, in this case, the MoDTC, succinimide, calcium sulfonate, and zinc dithiophosphate are used in combination (JP-A-59-122597).
Issue). However, even in such a combination, there is a drawback that the friction characteristics under different friction conditions are not sufficiently exhibited.

[0003]

Under the circumstances described above, the present invention is excellent in friction characteristics and wear resistance, and not only under severe friction conditions but also under mild friction conditions. The purpose of the present invention is to provide a lubricating oil composition which can maintain a low coefficient and is suitable as an industrial lubricating oil or an automotive lubricating oil, especially as an internal combustion engine lubricating oil of an automobile.

[0004]

As a result of intensive studies to develop a lubricating oil composition having the above-mentioned preferable properties, the present inventors have found that an alkyl having 11 or less carbon atoms can be added to a lubricating base oil. It was found that the object can be achieved by combining a mixture of a sulfurized oxymolybdenum dithiocarbamate having a group and a sulfurized oxymolybdenum dithiocarbamate having an alkyl group having 12 or more carbon atoms in a specific ratio and a specific additive. The present invention has been completed based on this finding.

That is, according to the present invention, (A) sulfurized oxymolybdenum dithiocarbamate 40 to 1 having an alkyl group having 12 to 22 carbon atoms is added to 100 parts by weight of a lubricating base oil.
0.005 to 0.2 part by weight of molybdenum and a mixture of 60 to 0% by weight of sulfurized oxymolybdenum dithiocarbamate having an alkyl group having 2 to 11 carbon atoms and (B) alkanolamine 0.1. To 2.0 parts by weight or (C) alkanolamide 0.1 to 2.0 parts by weight, and a lubricating oil composition,
A lubricating oil composition further comprising 1 to 10 parts by weight of succinimide as the composition component. Hereinafter, the present invention will be described in detail. The lubricating base oil used in the composition of the present invention is not particularly limited, and those conventionally used as a base oil for lubricating oil, such as mineral oil and synthetic oil, are used. Examples of the mineral oil include light neutral oil, medium neutral oil, heavy neutral oil, and bright stock. On the other hand, as the synthetic oil, for example, poly α-olefin oligomer, polybutene, alkylbenzene, polyol ester, polyglycol ester, dibasic acid ester, phosphoric acid ester,
Silicone oil etc. are mentioned. These base oils may be used alone, or two or more kinds may be used in combination, or a mineral oil and a synthetic base oil may be mixed and used. The base oil preferably has a kinematic viscosity at a temperature of 100 ° C. usually in the range of 3 to 20 cSt.

The component (A) of the lubricating oil composition of the present invention is a sulfurized oxymolybdenum dithiocarbamate represented by the following general formula [1], wherein R ¹ , R ² , R ³ and R ⁴ are alkyl having 12 to 22 carbon atoms. A mixture of a group and an alkyl group having 2 to 11 carbon atoms is used.

[Chemical 1] X ₁ , X ₂ , X ₃ and X ₄ : an oxygen atom or a sulfur atom,
They may be the same or different from each other. Sulfurized oxymolybdenum dithiocarbamate having an alkyl group having 12 to 22, preferably 12 to 18 and more preferably 13 to 15 carbon atoms in the component (A) of the lubricating oil composition of the present invention 40 to
100% by weight, preferably 50 to 90% by weight and carbon number 2
To 11, preferably 6 to 9 alkyl groups having a sulfurized oxymolybdenum dithiocarbamate of 60 to 0% by weight or less,
Preferably a mixture of 50 to 10% by weight is used. The component (A) of the lubricating oil composition of the present invention is 0.005-0.2 parts by weight in terms of the weight of molybdenum in the sulfurized oxymolybdenum dithiocarbamate molecule, relative to 100 parts by weight of the base oil.
Preferably 0.01 to 0.1 part by weight is used. When the amount of the component (A) used is less than 0.005, the effect of reducing the friction coefficient is not sufficiently exerted, and when it exceeds 0.2 parts by weight, sludge is likely to be the cause. Further, when the content of the alkyl group having 2 to 11 carbon atoms in the component (A) exceeds 40% by weight, the friction coefficient reducing effect is not sufficiently exerted and the oiliness effect is hardly exerted. The lubricating oil composition of the present invention contains 0.1 to 2.0 parts by weight of the alkanolamine or alkanolamide of the component (B) as an auxiliary agent.
Both can be used together as the component (B) of the lubricating oil composition of the present invention.

As the alkanolamine used in the present invention, alkanolmonoamines and alkanoldiamines represented by the following general formulas [2] and [3] can be used.

[Chemical 2] Here, R ¹ in the formula is an alkyl group having 12 to 22 carbon atoms, m
And n are numbers from 1 to 8.

[Chemical 3] Where at least one of X ₁ , X ₂ , X ₃ and X ₄ is
An alkyl group having 12 to 22 carbon atoms, other than the alkyl group, - a _{(CH 2 CH 2 O) m} -H group, m is 1
R ² is an alkenyl group having 1 to 6 carbon atoms. As the alkanolamide used in the present invention, those represented by the following general formula [4] can be used.

[Chemical 4] In the formula, R ³ is an alkyl group having 12 to 22 carbon atoms, and m and n are numbers from 1 to 8.

In the composition of the present invention, an ashless dispersant can be added, and succinimide is particularly suitable. The amount used may be 1 to 10 parts by weight with respect to 100 parts by weight of the base oil. Further, if desired, a metal detergent can be used in the lubricating oil composition of the present invention. As the metal detergent, known general ones can be used without limitation, and examples thereof include alkali metal or alkaline earth metal sulfonates, phenates, phosphonates, salicylates, and the like. Among these, calcium sulfonates are included. , Calcium phenate, magnesium sulfonate and magnesium phenate, calcium salicylate are preferred, especially overbased calcium sulfonate, neutral calcium sulfonate, overbased calcium phenate and overbased magnesium sulfonate, overbased calcium salicylate, neutral Calcium salicylate is preferred. These metal detergents may be used alone or in combination of two or more, and the content thereof is 0.3 to 4% by weight, preferably 0, based on the total weight of the composition. 0.5-2.5% by weight
Must be within the range. This amount is 0.3% by weight
If it is less than 4%, the cleaning effect is not sufficiently exerted, and if it exceeds 4% by weight, the ash content increases and the deposit increases inside the cylinder.

Further, an antiwear agent is optionally used in the composition of the present invention. This antiwear agent is, for example, zinc dithiophosphate (Z
nDTP) and zinc dithiocarbamate (ZnDTP)
Are preferred. These antiwear agents may be used alone or in combination of two or more, and the content thereof is 0.2 to 3 based on the total weight of the composition.
It should be in the range of weight%, preferably 0.5 to 1.5 weight%. If this content is less than 0.2% by weight, the wear resistance is significantly inferior, and if it exceeds 3% by weight, the phosphorus content in the oil may increase, and the reduction catalyst of exhaust gas may be poisoned. Occurs. The lubricating oil composition of the present invention, other than metal detergents, antiwear agents, to the extent that the objects of the present invention are not impaired, other additives as necessary, such as viscosity index improvers, pour point depressants, Antioxidants, rust preventives, corrosion inhibitors, antifoaming agents and the like can be added as appropriate. Examples of the viscosity index improver that can be used in the present invention include polymethacrylate-based, polyisobutylene-based, ethylene-
Examples thereof include a propylene copolymer system and a styrene-butadiene hydrogenated copolymer system, and these are usually used in a proportion of 0.5 to 35% by weight. Examples of the antioxidant used in the present invention include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine and alkylated-α-naphthylamine, 2,6-di-t-butyl-4-methylphenol, 4,4'-methylenebis (2,
6-di-t-butylphenol) and other phenolic antioxidants, etc., which can be used usually in a proportion of 0.05 to 2% by weight. Examples of the rust preventive used in the present invention include alkenyl succinic acid and its partial ester, corrosion inhibitors such as benzotriazole and benzimidazole, and defoaming agents such as dimethylpolysiloxane and polyacrylate. And these can be added appropriately.

[0010]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The friction coefficient of the lubricating oil composition was determined as follows. (1) Shell four-ball type test A shell four-ball type test was conducted under the conditions of a rotation speed of 2000 rpm, an oil temperature of 100 ° C., a load of 30 kgf, and a high-chromium carbon steel ball (SUJ-2) having a diameter of 1/2 inch to obtain a friction coefficient. . (2) LFW-1 friction test Using the tester shown in FIG. 1, the rotation speed was 250 rpm and the oil temperature was 6
The LFW-1 friction test was performed under the conditions of 0 ° C. and a load of 90 kgf using an R-type block manufactured by Falex (made of iron) and an S-10 test ring manufactured by Falex (made of iron). Figure 1
Inside, 1 is an S-10 test ring, 2 is an R-shaped block, and 3 is a strain gauge. A load is applied to the R-shaped block and the resistance generated when the ring is rotated is detected by a strain gauge to calculate the friction coefficient. The test oil is immersed in about half of the ring.

The friction coefficient of this example and the comparative example is represented by the Sommafeld number Z.

[Equation 1] μ: Viscosity coefficient [Pa · s] N: Slip velocity [m / s] w: Surface pressure [Pa] Corresponding to the numerical range of Sommafeld number below, one of the above friction tests (1) or (2) Applied Conditions of shell quaternary test Z = 10 ^-9 to 10 ^-10 [m] order LFW-1 test Z = 10 ^-8 [m] order It is necessary that the friction characteristics at different levels of Sommafeld number are excellent. Examples 1 to 11 and Comparative Examples 1 to 7 Lubricating oil compositions containing the base oil (100N) and the components of the types and amounts shown in Table 1 were prepared, and the friction coefficient was determined.
The results are shown in Table 1.

[0012]

[Table 1]

[0013]

[Table 2]

Note) MoDTC-A: MoDT having an alkyl group having 8 carbon atoms
MoDT with C50% by weight and C13 alkyl group
C 50% by weight mixture. MoDTC-B: MoDT having an alkyl group having 8 carbon atoms
MoDT with C30 wt% and C13 alkyl group
C 70% by weight mixture. MoDTC-C: MoD having an alkyl group having 13 carbon atoms
Mixture of 100% by weight TC. MoDTC-D: MoDT having an alkyl group having 8 carbon atoms
MoDT having C30% by weight and an alkyl group having 18 carbon atoms
C 70% by weight mixture. MoDTC-E: MoDT having an alkyl group having 8 carbon atoms
C 100% by weight mixture. MoDTC-F: MoDT having an alkyl group having 8 carbon atoms
MoDT with C80% by weight and C13 alkyl group
C 20% by weight mixture.

[0015]

INDUSTRIAL APPLICABILITY The lubricating oil composition of the present invention has excellent friction characteristics and wear resistance, and can maintain a low friction coefficient not only under severe friction conditions but also under mild friction conditions. It is preferably used as an industrial lubricating oil or an automobile lubricating oil, particularly as an automobile internal combustion engine lubricating oil.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus used in a LFW-1 friction test.

[Explanation of symbols]

 1 S-10 test ring 2 R type block 3 Strain meter

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Claims (1)

[Claims] (1) A (A) is added to 100 parts by weight of a lubricating base oil.
40 to 100% by weight of sulfurized oxymolybdenum dithiocarbamate having an alkyl group having 12 to 22 carbon atoms and 2 carbon atoms
A mixture consisting of 60 to 0% by weight of a sulfurized oxymolybdenum dithiocarbamate having an alkyl group of .about.11 and 0.005 to 0.2 part by weight of molybdenum and (B) an alkanolamine of 0.1 to 2.0 part by weight, or A lubricating oil composition comprising 0.1 to 2.0 parts by weight of an alkanolamide.