JPH08209178A - Lubricating oil composition - Google Patents

Abstract

(57) [Summary] (Corrected) [Composition] Based on the total weight of the lubricating oil composition in the lubricating base oil,
(A) 0.075 to 2% by weight of at least one organic molybdenum compound selected from the group consisting of molybdenum dithiocarbamate and molybdenum dithiophosphate, (b) 0.05 to 1.5% by weight of fatty acid ester and / or organic amide 0.05 to 0.5% by weight of the compound, and (c) 0.1 or more of at least one organozinc compound selected from the group consisting of zinc dithiophosphate and zinc dithiocarbamate.
The lubricating oil composition is characterized by containing 3 to 3% by weight. [Effect] Since it has excellent friction characteristics and wear resistance, and particularly has low frictional properties, it is suitable as a lubricating oil composition for low fuel consumption internal combustion engines.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lubricating oil composition,
More specifically, it relates to a lubricating oil composition for an internal combustion engine having a low coefficient of friction and good wear resistance. In particular, the present invention relates to a fuel-efficient lubricating oil composition for internal combustion engines having improved friction characteristics.

[0002]

2. Description of the Related Art Lubricating oil for internal combustion engines (hereinafter, abbreviated as "engine oil" if necessary) is mainly used for piston rings and cylinder liners, crankshafts and connecting rod bearings, cams and valve lifters. In addition to lubrication of various sliding parts such as valve trains, drive devices such as oil pumps and distributors, etc., they also serve to cool and clean the engine, disperse combustion products, and prevent rust and corrosion.

As described above, engine oils are required to have various performances, and the performances required are also changing as the performance of the internal combustion engine is increased, the output is increased, and the operating conditions are severer. Therefore, various additives such as a friction reducing agent, an antiwear agent, a metal detergent, an ashless dispersant, and an antioxidant are blended with the engine oil for the purpose of satisfying various performances.

As a basic function of the lubricating oil for an internal combustion engine, it is particularly important that the internal combustion engine be operated smoothly under all conditions to perform an anti-wear function. The lubrication part in the internal combustion engine is mostly in a fluid lubrication state, but is likely to be in a boundary lubrication state at the valve mechanism or the top and bottom dead center of the piston. Anti-wear properties of internal combustion engine lubricating oils under boundary lubrication are generally imparted by the addition of anti-wear agents such as zinc dithiophosphate (ZnDTP).

By the way, in an internal combustion engine, since a large amount of energy is lost in a friction portion where lubricating oil is involved, a friction reducing agent is added as a measure for reducing friction loss and fuel consumption. Conventionally, compounds such as molybdenum dithiocarbamate, fatty acid esters and octadecylamine have been used as friction reducing agents.

However, when the anti-wear agent and the friction reducing agent are used in combination, there arises a problem that the functions of both are not sufficiently exhibited due to competitive adsorption on the metal surface. That is ZnD
TP prevents wear caused by metal-metal contact by forming a protective film (boundary lubrication film) on the metal surface,
The friction-reducing agent also exerts the action of reducing friction by forming a surface film by adsorption on the metal surface, reaction with it, or polymer formation on the metal surface. Therefore,
When ZnDTP and a friction reducing agent are added to engine oil, the amount of ZnDTP adsorbed decreases due to competitive adsorption between the two on the metal surface, and wear resistance deteriorates. In some cases, a sufficient friction reducing effect cannot be obtained.

On the other hand, ZnDTP may interact with certain detergent-dispersants, resulting in impaired wear resistance. It may also affect the effect of the friction reducing agent. Therefore, sufficient consideration needs to be given to the selection of other additives such as a detergent dispersant and the concentration of such additives.

Conventionally, various proposals have been made to improve wear resistance and friction characteristics by using ZnDTP in combination with various additives. However, both wear resistance and friction reducing effect are satisfied, and clean dispersibility is obtained. It is still unsatisfactory in terms of providing engine oil that satisfies various functions such as.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lubricating oil composition for an internal combustion engine which is excellent in both friction characteristics and wear resistance and which retains other necessary characteristics as a lubricating oil for an internal combustion engine. To do.

As a result of intensive studies to overcome the above-mentioned problems of the prior art, the present inventor has found that a specific amount of an organic molybdenum compound, a fatty acid ester and / or an organic amide compound, and zinc dithiophosphate and / or zinc dithiocarbamate. By using an organozinc compound such as, as an essential component, without impairing wear resistance and other properties,
It has been found that the friction characteristics can be improved, and the present invention has been completed based on the findings. Furthermore, one or more of calcium sulfonate, magnesium sulfonate, calcium phenate, magnesium phenate, calcium salicylate, and magnesium salicylate are added to the organic molybdenum compound, the fatty acid ester and / or the organic amide compound and the organic zinc compound as a metal detergent, and ashless. By using in combination with one or more of benzylamine, polyalkenylsuccinimide, a benzylamine boron derivative or a polyalkenylsuccinimide boron derivative as a detergent dispersant, abrasion resistance and friction characteristics, and other necessary properties as an engine oil can be obtained. We have found that it also improves quality.

[0011]

Thus, according to the present invention, a lubricating base oil (a) is added based on the total weight of the lubricating oil composition.
0.075 to 2% by weight of at least one organic molybdenum compound selected from the group consisting of molybdenum dithiocarbamate and molybdenum dithiophosphate, (b) 0.05 to 1.5% by weight of fatty acid ester, and / or organic amide compound 0 0.05 to 0.5% by weight, and (c) 0.1 to 3% by weight of at least one organozinc compound selected from the group consisting of zinc dithiophosphate and zinc dithiocarbamate. A lubricating oil composition is provided. Further, (d) at least one compound selected from the group consisting of calcium sulfonate, magnesium sulfonate, calcium phenate, magnesium phenate, calcium salicylate and magnesium salicylate as the components (a), (b) and (c). 0.
1 to 10% by weight, and (e) 0.5 to 1 of at least one compound selected from the group consisting of benzylamine, a boron derivative of benzylamine, a polyalkenylsuccinimide and a polyalkenylsuccinimide boron derivative.
A lubricating oil composition containing 5% by weight is provided.

The present invention will be described in detail below. As the base oil used in the present invention, mineral oil, synthetic oil and vegetable oil can be used. As the mineral oil, a solvent refined raffinate obtained by contacting a lubricating oil raw material derived by distillation of crude oil under atmospheric pressure or reduced pressure with an aromatic component extraction solvent such as phenol, furfural, or N-methylpyrrolidone, or a lubricating oil raw material A hydrotreated oil obtained by hydrotreating under a hydrotreating condition, an isomerized oil obtained by contacting a petroleum wax with hydrogen in the presence of isomerization, or a solvent refining step and a hydrotreating step. A refined oil obtained from the lubricating oil refining step in which the above are combined can be mentioned. The dewaxing step, the hydrofinishing step, the clay treatment step and the like can be arbitrarily adopted by ordinary methods by any of the production methods of solvent refining, hydrotreating and isomerizing. Specific examples of the mineral oil include light neutral oil, medium neutral oil, heavy neutral oil, and bright stock. Examples of the synthetic oil include poly α-olefin, polybutene, alkylbenzene, polyol ester, dibasic acid ester, phosphoric acid ester, silicone oil and the like.
These base oils may be used alone or in admixture of two or more, and mineral oil and synthetic oil may be mixed and used. The viscosity of the base oil is not limited, but 1
00 kinematic viscosity typically 3 to 20 mm ² / s at ° C., it is especially preferred in the range of 3.5~12mm ² / s. As the friction reducing agent, various kinds of molybdenum dithiophosphates and dithiocarbamates, fatty acids and their esters, amide compounds, amine compounds, phosphoric acid esters, sulfurized esters, etc. have been known so far. In the present invention, a specific amount of (a) at least one compound selected from the group consisting of molybdenum dithiocarbamate (MoDTC) and molybdenum dithiophosphate (MoDTP), and (b) a fatty acid ester and / or an organic amide compound are specified. Amount of (c) at least one organozinc compound selected from the group consisting of zinc dithiophosphate and zinc dithiocarbamate is used in combination. MoDTC and MoDTP used in the present invention are organic molybdenum compounds represented by the following general formulas [I] and [II], respectively. General formula [I}

Embedded image General formula [II]

Embedded image

In the general formulas [I] and [II], the meaning of each symbol is as follows. R ^{1 to} R ⁴ : hydrogen atom; saturated or unsaturated alkyl group having 1 to 18 carbon atoms: cycloalkyl group having 6 to 18 carbon atoms; aryl group having 6 to 26 carbon atoms, alkylaryl group or arylalkyl group; or Ester bond, ether bond,
A hydrocarbon group containing an alcohol group or a carboxyl group, which may be the same or different from each other. X ¹ and X ² : oxygen atoms or sulfur atoms, which may be the same or different from each other. Y ¹ and Y ² : oxygen atoms or sulfur atoms, which may be the same or different from each other.

In the general formulas [I] and [II], R ^{1 to} R ⁴
Is preferably a saturated or unsaturated alkyl group having 3 to 18 carbon atoms, a cycloalkyl group having 6 to 18 carbon atoms, or an alkylaryl group having 6 to 18 carbon atoms. Specific preferred examples thereof include, for example, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, n-hexyl, 2-ethylhexyl, n-octyl, nonyl,
An alkyl or alkenyl group having 3 to 18 carbon atoms such as decyl, lauryl, tridecyl, oleyl and linoleyl,
Examples include alkylaryl groups such as nonylphenyl.

MoDTC or MoDTP may be used alone or in combination of two or more, and further, M
A combination of oDTC and MoDTP can be used. MoDTC and / or MoDTP is 0.075 to 2% by weight, preferably 0.075 to 2% by weight based on the total weight of the composition.
Used at a rate of 1.7% by weight. If this usage ratio is too small, the friction characteristics are not improved so much, and if it is too large, the wear resistance is deteriorated.

According to the present invention, as the fatty acid ester,
Examples thereof include mono- or diesters of fatty acid and glycerin, and mono- or diesters of sorbitan. The fatty acid glyceride is a mono- or diester represented by the following general formula [III] or [IV]. General formula [III]

Embedded image General formula [IV]

[Chemical 4] However, R ^{5 to} R ⁷ are saturated or unsaturated alkyl groups having 8 to 22 carbon atoms. The fatty acid esters may be used alone or in combination of two or more, and the use ratio thereof is 0.05-based on the total weight of the composition.
It is 1.5% by weight. If this proportion is too small, the effect of improving the friction characteristics is small, and if it is too large, the wear resistance deteriorates. A preferred use ratio is 0.075 to 1.5% by weight. The organic amide compound used in the present invention is a compound represented by the following general formula [V]. General formula [V]

Embedded image In general formula [V], the meaning of each symbol is as follows. R ^8, R ^9: a hydrogen atom; a cycloalkyl group having a carbon number of 6 to 26; saturated or unsaturated alkyl group having 1 to 20 carbon atoms;
An aryl group having 6 to 26 carbon atoms, an alkylaryl group or an arylalkyl group; or an alkylene oxide group having 2 to 30 carbon atoms, which may be the same or different. R ¹⁰ : hydrogen atom; saturated or unsaturated alkyl group having 1 to 20 carbon atoms; cycloalkyl group having 6 to 26 carbon atoms; aryl group, alkylaryl group or arylalkyl group having 6 to 26 carbon atoms; or ester bond , A hydrocarbon group containing an ether bond, an alcohol group or a carboxyl group. Here, the alkylene oxide group is a group represented by the following general formulas [VI] and / or [VII]. General formula [VI]

[Chemical 6] General formula [VII]

[Chemical 7] In general formulas [VI] and [VII], the meaning of each symbol is as follows. n: integers 1 to 10 R ¹¹ and R ¹² : a hydrogen atom or a methyl group. In general formula [V], R ⁸ and R ⁹ are preferably hydrogen atoms, saturated or unsaturated alkyl groups having 2 to 8 carbon atoms, cycloalkyl groups having 8 to 14 carbon atoms, and alkyl groups having 8 to 14 carbon atoms. An alkylene oxide group such as an aryl group, ethylene oxide, or propylene oxide (n = 1 to 5).
In the general formula [V], R ¹⁰ preferably has 6 to 6 carbon atoms.
18 saturated or unsaturated alkyl groups, 12 to 24 carbon atoms
Or a cycloalkyl group having 12 to 24 carbon atoms. Specific examples of such an organic amide compound include oleic acid amide and lauric acid amide. The proportion of the organic amide compound used is 0.05 to 0.5% by weight, preferably 0.0.
It is 5 to 0.3% by weight. By adding the organic amide compound, the coefficient of friction can be reduced from the initial stage while suppressing the copper corrosiveness. If this usage rate is too small, the effect of reducing the friction coefficient from the beginning is small, and if too large, the effect is saturated.

As the organozinc compound (c) of the present invention,
Zinc dithiophosphate (ZnDTP) and zinc dithiocarbamate (ZnDTC) represented by the following general formulas [VIII] and [IX] are used.

General formula [VIII]

Embedded image

General formula [IX]

[Chemical 9]

In the general formulas [VIII] and [IX], the meaning of each symbol is as follows. R ¹³ and R ¹⁴ : hydrogen atom; primary (pr) or secondary (sec) saturated or unsaturated alkyl group having 1 to 18 carbon atoms; 6 to 1 carbon atom
An 8 cycloalkyl group; an aryl group having 6 to 18 carbon atoms,
An alkylaryl group or an arylalkyl group; or a hydrocarbon group containing an ester bond, an ether bond, an alcohol group or a carboxyl group, which may be the same or different from each other. General formulas [VIII] and [IX]
Among them, R ¹³ and R ¹⁴ are preferably a saturated or unsaturated alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 8 to 18 carbon atoms, and an alkylaryl group having 8 to 18 carbon atoms. ZnDTP and ZnDTC can be used alone or in combination thereof, and the use ratio thereof is 0.1 to 3% by weight based on the total weight of the composition. A preferred use ratio is 0.1 to 2% by weight.

Various metal detergents such as barium, calcium, magnesium, and other phenates, sulfonates, salicylates, phosphonates, etc. have been known so far, but in the present invention, calcium sulfonate, magnesium sulfonate, calcium phenate. , At least one compound selected from the group consisting of magnesium phenate, calcium salicylate and magnesium salicylate.

These metal detergents are used in a proportion of 0.1 to 10% by weight, preferably 0.2 to 5%, based on the total weight of the composition.

In the present invention, at least one compound selected from the group consisting of benzylamine, a boron derivative of benzylamine, a polyalkenylsuccinimide and a boron derivative of a polyalkenylsuccinimide is used as the ashless detergent dispersant. To do.

The ashless detergent dispersant is used in a proportion of 0.5 to 15% by weight, preferably 1.0 to 7.5% by weight, based on the total weight of the composition.

In the lubricating oil composition for internal combustion engines of the present invention, other additives such as antioxidants, viscosity index improvers, pour point depressants, etc. may be added, if necessary, unless the object of the present invention is impaired. A rust preventive agent, a defoaming agent, a corrosion inhibitor and the like can be added as appropriate.

Examples of the antioxidant include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine and alkylated-α-naphthylamine, 2,6-di-t-butylphenol, 4,4'- Methylenebis- (2,6-di-t-butylphenol),
Examples include phenolic antioxidants such as 4,4′-thiobis- (6-t-butyl-o-cresol), which are usually used in a proportion of 0.05 to 2.0% by weight. To be done.

Examples of the viscosity index improver include polymethylmethacrylate type, polyisobutylene type, ethylene-propylene copolymer type, styrene-butadiene hydrogenated copolymer type, etc., and usually 0.5 to 35% by weight. Used in proportion.

Examples of the rust preventive agent include polyalkenyl succinic acid and partial esters thereof, which can be appropriately added. Examples of the defoaming agent include dimethylpolysiloxane and polyacrylate, which can be appropriately added.

[0049]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The methods for measuring the physical properties are as follows.

<Friction / Abrasion Characteristics> Using a shell four-ball tester, the friction coefficient and wear scar diameter (m
m) was measured. The test conditions are as follows.

Load: 40 kg Oil temperature: 90 ° C. Rotation speed: 1800 rpm Test time: 30 minutes

Example 1-35, Comparative Example 1-14 Each test oil was prepared by mixing the base oils shown in Tables 1 to 4 with each component. The components used are as follows.

(1) Base oil Mineral oil: 150 neutral mineral oil; kinematic viscosity at 100 ° C. 5.1 cSt. Hydrotreated oil: Hydrotreated oil equivalent to 150 neutral Synthetic oil: Poly α-olefin 80% by weight and diisodecyl adipate 20% by weight Mineral oil / hydrotreated oil: Mineral oil 50% by weight and hydrotreated oil 5
0% by weight (2) MoDTC: molybdenum dithiocarbamate (alkyl group having 8 carbon atoms) (3) MoDTP: molybdenum dithiophosphate (alkyl group having 8 carbon atoms) (4) Fatty acid glyceride: oleyl monoglyceride 50% by weight and oleyl diglyceride 50 Wt% mixture

(5) Organic amide compound: oleic acid amide (6) Ca-S (overbased): overbased calcium sulfonate (7) Ca-S (neutral): neutral calcium sulfonate (8) Ca-P (Overbased): Overbased calcium phenate (9) Mg-S (Overbased): Overbased magnesium sulfonate (10) Boron-based benzylamine (11) Polyalkenyl succinimide:

General formula [X]

[Chemical 10] (However, PiB represents polyisobutylene.) (12) Boron-based polyalkenyl succinimide (13) sec-C _3-6 ZnDTP: zinc dithiophosphate (alkyl group is secondary, carbon number 3 and 6) ) (14) pr-C _3-6 ZnDTP: zinc dithiophosphate (alkyl group is primary, carbon number 3 and 6) (15) sec-C _3-6 ZnDTC: zinc dithiocarbamate (alkyl group is second Class 3 and carbon number 3) The usage ratio of each additive component in Tables 1 to 4 is% by weight based on the total amount of the composition, and the balance is base oil (total 100% by weight).

[0056]

[Table 1]

[Table 2]

[Table 3]

[Table 4] As is clear from Tables 1 to 4, Mo is used as a friction reducing agent.
By combining DTC and / or MoDTP with a fatty acid ester and / or an organic amide compound and ZnDTP and / or ZnDTC as an antiwear agent in a specific ratio, and further combining with a metal detergent and an ashless detergent dispersant, the friction coefficient becomes A lubricating oil composition having a small size and a small wear scar diameter can be obtained. It has been clarified that when the content is out of the above-specified range, the frictional properties and the wear resistance are remarkably deteriorated as shown in Comparative Examples, and the practical value is difficult.

[0057]

EFFECTS OF THE INVENTION According to the present invention, there is provided a lubricating oil composition for an internal combustion engine, which has both excellent frictional properties and wear resistance and retains other necessary properties as a lubricating oil for an internal combustion engine.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C10M 133: 16) (C10M 169/04 137: 10 135: 18 129: 74 133: 16 159: 22 159: 24 ) C10N 10:04 10:12 30:04 30:06 40:25

Claims (2)

[Claims] 1. A lubricating base oil comprising 0.075-2% by weight of at least one organic molybdenum compound selected from the group consisting of (a) molybdenum dithiocarbamate and molybdenum dithiophosphate, based on the total weight of the lubricating oil composition. ,
(B) 0.05 to 1.5% by weight of fatty acid ester and / or 0.05 to 0.5% by weight of organic amide compound, and (c) at least one selected from the group consisting of zinc dithiophosphate and zinc dithiocarbamate A lubricating oil composition comprising 0.1 to 3% by weight of the organozinc compound. 2. Further, 0.1 to 10% by weight of (d) at least one compound selected from the group consisting of calcium sulfonate, magnesium sulfonate, calcium phenate, magnesium phenate, calcium salicylate and magnesium salicylate, and ( e) 0.5 to 15% by weight of at least one compound selected from the group consisting of benzylamine, a benzylamine boron derivative, a polyalkenylsuccinimide and a polyalkenylsuccinimide boron derivative. The lubricating oil composition described.