JPH10287895A - Lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition useful for an internal combustion engine, etc., capable of exhibiting high oxidation stability, usable under severe conditions, by mixing a base oil comprising a specific saturated hydrocarbon component and an aromatic hydrocarbon component with a prescribed amount of a sulfur-containing antioxidant. SOLUTION: This composition is obtained by formulating (A) a base oil comprising (A1 ) 70-97 (mass)% of a saturated hydrocarbon component and (A2 ) 2-30 wt.% of an aromatic hydrocarbon component, has <=1 (mass)% of resin content, a value of the equation: kp<1> [RH]<1> kp<1> is a rate constant (M<-1> S<-1> ) of hydrogen drawing reaction by t-butyl peroxyradical (Z) of the component A1 at 40 deg.C; [RH]<1> is an average number of mols of the component A1 of A1 1L} of <=0.3 and a value of kp<2> [RH]<2> kp<2> is a rate constant (M<-1> S<-1> ) of hydrogen drawing reaction by Z of the component A1 at 40 deg.C; [RH]<2> is an average number of mols of the component A2 of A2 1L} of 1-20 with (B) 0.01-10 pts.wt. of a sulfur-containing antioxidant such as a compound of the formula (R<1> to R<4> are each a 1-18C hydrocarbon group).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition having excellent oxidative stability and particularly suitable for use in an internal combustion engine.

[0002]

2. Description of the Related Art Generally, lubricating oil in an internal combustion engine is exposed to a high temperature portion such as between a piston and a cylinder, and deteriorates by reaction with air or combustion gas. On the other hand, recently, automobiles equipped with a three-way catalyst have been increasing for emission control measures, and it has been allowed to operate the internal combustion engine more severely. Further, from the viewpoint of energy saving, the weight of an automobile body has been reduced for the purpose of improving fuel efficiency, and accordingly, the size of a crankcase has been reduced, and the amount of crankcase oil has been reduced. As a result, the lubricating oil will be used under more severe conditions. In recent years, a gas engine using a gas such as natural gas, LPG, or cracked gas has been frequently used.

[0003] For these reasons, the oxidation stability of lubricating oils has recently become more important, whereas zinc dithiophosphates, hindered phenols and aromatics have hitherto been used for mineral oils or synthetic oil base oils. This problem has been solved by adding an antioxidant such as an aromatic amine, but has not been sufficient.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lubricating oil composition having a higher oxidative stability by further improving the oxidative stability of the lubricating oil.

[0005]

That is, the present invention provides:
(1) A base oil containing 70 to 97% by mass of a saturated hydrocarbon component and 2 to 30% by mass of an aromatic hydrocarbon component, and having a resin content of 1% by mass or less, wherein kp ^{1 of the} saturated hydrocarbon component is
[RH] ¹ (kp ¹ (M ⁻¹ s ⁻¹ ) is the t-
[RH] ¹ (M) represents the average number of moles of the saturated hydrocarbon component in 1 L of the saturated hydrocarbon component at 40 ° C., respectively. ) Is equal to or less than 0.3 (s ^-1 ) and kp ² [RH] ² (kp ² (M ⁻¹ s ⁻¹ ) of the aromatic hydrocarbon component
Is the rate constant of the hydrogen abstraction reaction with t-butylperoxy radical at 40 ° C., [RH] ² (M) is 4
The average mole number of the aromatic hydrocarbon component in 1 L of the aromatic hydrocarbon component at 0 ° C. is respectively shown. ) Is from 1 to 20 (s ^-1 ) with respect to 100 parts by weight of the base oil.
(2) To provide a lubricating oil composition containing 0.01 to 10 parts by weight of a sulfur-containing antioxidant.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the contents of the present invention will be described in detail. The base oil used in the present invention has a saturated hydrocarbon component of 7%.
0 mass% or more, preferably 75 mass% or more and 97 mass% or less, preferably 92 mass% or less. If the content of the saturated hydrocarbon component in the base oil is less than 70% by mass or more than 97% by mass, it is not preferable because sufficient oxidation stability cannot be obtained.

The base oil used in the present invention contains an aromatic hydrocarbon component in an amount of 2% by mass or more, preferably 5% by mass or more and 30% by mass or less, preferably 25% by mass or less. The content of aromatic hydrocarbon component in the base oil is 2% by mass
If it is less than 30% by mass or if it exceeds 30% by mass, sufficient oxidation stability cannot be obtained, which is not preferable.

The base oil used in the present invention has a resin content of 1% by mass or less, preferably 0.8% by mass or less. If the content of the resin component in the base oil exceeds 1% by mass, it is not preferable because sufficient oxidation stability cannot be obtained.

In the present invention, the contents of the saturated hydrocarbon component, the aromatic hydrocarbon component and the resin component are as defined in Analytica.
l Chemistry Vol. 44, No. 6, (1972) pp. 915-919, "Separation of Hi"
gh-Boiling Petroleum Dist
illates Using Gradient El
union Through Dual-Packed
(Silica Gel-Alumina Gel)
Adsorption Columns ", which is based on the silica-alumina gel chromatographic analysis method described in
In this method, silica gel is placed below and alumina gel is placed above, and n-heptane is used to elute the saturated hydrocarbon component, benzene is used to elute the aromatic hydrocarbon component, and the resin component (or the polar compound) is eluted. Is measured by a method capable of separating an aromatic hydrocarbon component and a resin component in a sample by using methanol.

In the present invention, kp of the saturated hydrocarbon component is
¹ [RH]¹ (Kp¹ (M^-1s^-1) Is t at 40 ° C.
Of hydrogen abstraction reaction by -butylperoxy radical
The rate constant is [RH]¹ (M) is saturated carbon at 40 ° C
Average of the saturated hydrocarbon component in 1 L of hydride component
Represents the number of moles. ) Is 0.3 (s^-1) Less preferred
Or 0.2 (s^-1It is important that: Bored
Kp of Japanese hydrocarbon component ¹ [RH]¹ Is 0.3 (s^-1)
If it exceeds, it is not preferable because sufficient oxidation stability cannot be obtained.
I don't.

In the present invention, kp ² [RH] ² (kp ² (M ⁻¹ s ⁻¹ )) of the aromatic hydrocarbon component is a rate constant of a hydrogen abstraction reaction by a t-butylperoxy radical at 40 ° C. [RH] ² (M) represents the average number of moles of the aromatic hydrocarbon component in 1 L of the aromatic hydrocarbon component at 40 ° C.) is 1 (s ⁻¹ ) or more, preferably 2 (s ^{−). 1} ) or more and 20 (s ^-1 ) or less, preferably 18 (s ^-1 ) or less. When kp ² [RH] ² of the aromatic hydrocarbon component is less than 1 (s ⁻¹ ) or more than 20 (s ⁻¹ ), sufficient oxidation stability cannot be obtained, which is not preferable.

In the present invention, kp (M ^-1 s ^-1 ) such as kp ¹ and kp ² , [RH] (M) such as [RH] ¹ and [RH] ^2, and kp ¹ [RH] ¹ And k
kp [RH] (s ^-1 ) such as p ² [RH] ²
adian Journalnal Chemistry
47, 3809-3815, "Absolute
rate constants for hydroc
arbon automation. XVII.
The oxidation of some cy
clicks (J. Howard)
and K. U. Ingold) ", that is, oxidation is started by adding an initiator to a sample and a solution of tetralin hydroperoxide in an oxygen atmosphere, and a time change of the oxygen pressure at this time is measured.
In the method of obtaining kp from the change, the temperature is set to 40 ° C.
And instead of tetralin hydroperoxide, t-
It means the value measured using butyl hydroperoxide and α, α′-azo-bis-isobutyronitrile as the initiator.

The kinematic viscosity at 40 ° C. of the base oil used in the present invention is not particularly limited, but is at least 5 mm ² / s, preferably at least 10 mm ² / s, and 200
mm ² / s or less, preferably 100 mm ² / s or less. The kinematic viscosity at 40 ° C of the base oil is 5m
An m ² / s or more is preferable because oil film formation is sufficient, lubricity is excellent, and evaporation loss of the base oil under high temperature conditions can be reduced. On the other hand, setting the kinematic viscosity at 40 ° C. of the base oil to 200 mm ² / s or less is preferable because the fluid resistance is reduced and the frictional resistance at the lubricating point is reduced.

The kinematic viscosity of the base oil at 100 ° C. is not particularly limited, but is not less than 0.5 mm ² / s.
Preferably at 1 mm ² / s or more and 100 mm ²
/ S or less, preferably 50 mm ² / s or less. The kinematic viscosity at 100 ° C. of the base oil is 0.5 mm
^An oil content of ² / s or more is preferable because oil film formation is sufficient, lubricity is excellent, and evaporation loss of base oil under high temperature conditions can be reduced. On the other hand, setting the kinematic viscosity at 100 ° C. of the base oil to 100 mm ² / s or less is preferable because the fluid resistance is reduced and the frictional resistance at the lubricating point is reduced.

Although the viscosity index of the base oil is not particularly limited, it is desirably 50 or more, preferably 80 or more. It is preferable to set the viscosity index of the base oil to 50 or more because both the oil film forming ability and the fluid resistance reducing ability can be achieved.

Although the pour point of the base oil is not particularly limited, it is desirably 0 ° C. or lower, preferably -5 ° C. or lower. By setting the pour point of the base oil to 0 ° C. or lower, the motion of the machine is not hindered at low temperatures, which is preferable.

The sulfur-containing antioxidants which are essential components of the present invention include metal dihydrocarbyl dithiophosphates such as zinc dihydrocarbyl dithiophosphate and molybdenum dihydrocarbyl dithiophosphate; zinc dihydrocarbyl dithiocarbamate, molybdenum dihydrocarbyl dithiocarbamate, Metal dithiocarbamates such as copper hydrocarbyl dithiocarbamate; sulfides and mixtures thereof; and among these, zinc dihydrocarbyl dithiophosphate, zinc dihydrocarbyl dithiocarbamate, molybdenum dihydrocarbyl dithiocarbamate, and sulfides are preferable.

As a preferred example of the sulfur-containing antioxidant, zinc dihydrocarbyl dithiophosphate includes a compound represented by the following general formula (1).

[0019]

Embedded image

In the general formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrocarbon group having 1 to 18 carbon atoms;
Examples of such a hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a linear or branched pentyl group, Straight or branched hexyl group, straight or branched heptyl group, straight or branched octyl group, straight or branched nonyl group, straight or branched decyl group, straight or branched chain An undecyl group,
Straight or branched dodecyl group, straight or branched tridecyl group, straight or branched tetradecyl group, straight or branched pentadecyl group, straight or branched hexadecyl group, straight or branched An alkyl group having 1 to 18 carbon atoms such as a heptadecyl group, a linear or branched octadecyl group;
Straight or branched butenyl, straight or branched pentenyl, straight or branched hexenyl, straight or branched heptenyl, straight or branched octenyl, straight or branched A nonenyl group, a straight or branched decenyl group, a straight or branched undecenyl group, a straight or branched dodecenyl group, a straight or branched tridecenyl group, a straight or branched tetradecenyl group, A chain or branched pentadecenyl group, a straight or branched hexadecenyl group,
A C 4-18 alkenyl group such as a straight-chain or branched heptadecenyl group, a straight-chain or branched octadecenyl group; a C5-C7 cycloalkyl group such as a cyclopentyl group, a cyclohexyl group or a cycloheptyl group; methyl Cyclopentyl group, dimethylcyclopentyl group (including all structural isomers), methylethylcyclopentyl group (including all structural isomers), diethylcyclopentyl group (including all structural isomers), methylcyclohexyl group, dimethylcyclohexyl group (Including all structural isomers), methylethylcyclohexyl group (including all structural isomers), diethylcyclohexyl group (including all structural isomers), methylcycloheptyl group, dimethylcycloheptyl group (including all structural isomers) Isomer), methylethylcycloheptyl group (including C6-C11 alkylcycloalkyl groups such as diethylcycloheptyl group (including all structural isomers); aryl groups such as phenyl group and naphthyl group: tolyl group (including all structural isomers) Xylyl group (including all structural isomers), ethylphenyl group (including all structural isomers), linear or branched propylphenyl group (including all structural isomers) A linear or branched butylphenyl group (including all structural isomers), a linear or branched pentylphenyl group (including all structural isomers), a linear or branched hexylphenyl group (all ), A linear or branched heptylphenyl group (including all structural isomers), a linear or branched octylphenyl group (including all structural isomers), a linear or branched branch (Including all structural isomers) nonylphenyl group, a linear or branched decylphenyl group (including all structural isomers),
Each alkylaryl group having 7 to 18 carbon atoms such as a linear or branched undecylphenyl group (including all structural isomers) and a linear or branched dodecylphenyl group (including all structural isomers) A benzyl group, a phenylethyl group,
Phenylpropyl group (including isomer of propyl group), phenylbutyl group (including isomer of butyl group), phenylpentyl group (including isomer of pentyl group), phenylhexyl group (including isomer of hexyl group) 7)
To 12 arylalkyl groups.

The above-mentioned alkyl group or alkenyl group may be a so-called primary alkyl group or alkenyl group in which the carbon atom bonded to oxygen is a primary carbon, and the carbon atom is secondary. Or a so-called secondary alkyl group or alkenyl group, or a tertiary alkyl or alkenyl group in which the carbon atom is tertiary.

Among the compounds represented by the general formula (1),
Zinc dialkyldithiophosphates in which R ¹ , R ² , R ³ and R ⁴ are each independently a linear or branched alkyl group having 1 to 18 carbon atoms, provide a lubricating oil composition having particularly excellent antioxidant properties. It is preferable in giving. In the present invention, two or more kinds of zinc dihydrocarbyl dithiophosphates included in the general formula (1) can be used as zinc dihydrocarbyl dithiophosphate in an arbitrary mixture ratio.

Specific examples of zinc dihydrocarbyl dithiophosphate include zinc diethyl dithiophosphate, zinc di-n-propyl dithiophosphate, zinc diisopropyl dithiophosphate,
Zinc di-n-butyldithiophosphate, zinc diisobutyldithiophosphate, zinc disec-butyldithiophosphate, dite
rt-butyl zinc dithiophosphate, di (linear or branched pentyl) zinc dithiophosphate, di (linear or branched hexyl) zinc dithiophosphate, di (linear or branched heptyl)
Zinc dithiophosphate, di (straight or branched octyl) zinc dithiophosphate, di (straight or branched nonyl) zinc dithiophosphate, di (straight or branched decyl) zinc dithiophosphate, di (straight or branched) Undecyl) zinc dithiophosphate, di (linear or branched dodecyl) zinc dithiophosphate,
Zinc di (straight or branched tridecyl) dithiophosphate, zinc di (straight or branched tetradecyl) dithiophosphate, zinc di (straight or branched pentadecyl) dithiophosphate, di (straight or branched hexadecyl) dithiophosphate Zinc, di (linear or branched octadecyl) zinc dithiophosphate, zinc diphenyldithiophosphate, zinc diethylphenyldithiophosphate, zinc dipropylphenyldithiophosphate, zinc diisopropylphenyldithiophosphate, zinc dibutylphenyldithiophosphate, zinc dipentylphenyldithiophosphate , Zinc dihexylphenyldithiophosphate, zinc diheptylphenyldithiophosphate, zinc dioctylphenyldithiophosphate, zinc di-2-ethylhexylphenyldithiophosphate, zinc dinonylphenyldithiophosphate, didecylphenyldithiophosphate Zinc phosphate, zinc diundecylphenyldithiophosphate, zinc didodecylphenyldithiophosphate, zinc ditridecylphenyldithiophosphate, zinc ditetradecylphenyldithiophosphate, zinc dipentadecylphenyldithiophosphate, zinc dihexadecylphenyldithiophosphate, Zinc heptadecylphenyldithiophosphate, zinc dioctadecylphenyldithiophosphate or mixtures thereof can be mentioned.

As another preferred example of the sulfur-containing antioxidant, zinc dihydrocarbyldithiocarbamate includes those represented by the following general formula (2).

[0025]

Embedded image

In the above general formula (2), R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represent a hydrocarbon group having 1 to 18 carbon atoms, such as a methyl group,
Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, linear or branched pentyl group, linear or branched hexyl group, linear or Branched heptyl, straight or branched octyl, straight or branched nonyl, straight or branched decyl, straight or branched undecyl, straight or branched dodecyl Linear or branched tridecyl group, linear or branched tetradecyl group, linear or branched pentadecyl group, linear or branched hexadecyl group, linear or branched heptadecyl group, linear or branched A C1-C18 alkyl group such as a branched octadecyl group; a linear or branched butenyl group, a linear or branched pentenyl group, a linear or branched hexenyl group, a linear or branched heptenyl group A straight or branched octenyl group, a straight or branched nonenyl group, a straight or branched decenyl group, a straight or branched undecenyl group, a straight or branched dodecenyl group, a straight or branched Branched tridecenyl group, straight or branched tetradecenyl group, straight or branched pentadecenyl group, straight or branched hexadecenyl group, straight or branched heptadecenyl group, straight or branched octadecenyl group, etc. An alkenyl group having 4 to 18 carbon atoms; a cycloalkyl group having 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexyl group and a cycloheptyl group; a methylcyclopentyl group, a dimethylcyclopentyl group (including all structural isomers); Cyclopentyl group (including all structural isomers), diethylcyclopentyl group (including all structural isomers), methyl Cyclohexyl, dimethylcyclohexyl (including all structural isomers), methylethylcyclohexyl (including all structural isomers), diethylcyclohexyl (including all structural isomers), methylcycloheptyl, dimethylcyclo Alkylcyclo having 6 to 11 carbon atoms such as a heptyl group (including all structural isomers), a methylethylcycloheptyl group (including all structural isomers), and a diethylcycloheptyl group (including all structural isomers). Alkyl groups; aryl groups such as phenyl and naphthyl groups; tolyl groups (including all structural isomers), xylyl groups (including all structural isomers), ethylphenyl groups (including all structural isomers), Straight or branched propylphenyl group (including all structural isomers), straight or branched butylphenyl group (all ), A linear or branched pentylphenyl group (including all structural isomers), a linear or branched hexylphenyl group (including all structural isomers), a linear or branched A branched heptylphenyl group (including all structural isomers), a linear or branched octylphenyl group (including all structural isomers), a linear or branched nonylphenyl group (including all structural isomers) Straight chain or branched decylphenyl groups (including all structural isomers),
Each alkylaryl group having 7 to 18 carbon atoms such as a linear or branched undecylphenyl group (including all structural isomers) and a linear or branched dodecylphenyl group (including all structural isomers) A benzyl group, a phenylethyl group,
Phenylpropyl group (including isomer of propyl group), phenylbutyl group (including isomer of butyl group), phenylpentyl group (including isomer of pentyl group), phenylhexyl group (including isomer of hexyl group) 7)
To 12 arylalkyl groups.

The above-mentioned alkyl group or alkenyl group may be a so-called primary alkyl group or alkenyl group in which the carbon atom bonded to the nitrogen atom is a primary carbon, and the carbon atom is a secondary carbon atom. It may be a so-called secondary alkyl group or alkenyl group, or a tertiary alkyl or alkenyl group in which the carbon atom is tertiary.

Among the compounds represented by the general formula (2),
Zinc dialkyldithiocarbamate wherein R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently an alkyl group having 4 to 13 carbon atoms is particularly preferred from the viewpoint of providing a lubricating oil composition having high oxidation stability.

Particularly preferred specific examples of zinc dihydrocarbyl dithiocarbamate include, for example, zinc di (linear or branched) butyldithiocarbamate, zinc di (linear or branched) pentyldithiocarbamate,
Zinc di (straight or branched) hexyldithiocarbamate, zinc di (straight or branched) heptyldithiocarbamate, zinc di (straight or branched) octyldithiocarbamate, di (straight or branched) nonyldithiocarbamate Zinc, zinc di (linear or branched) decyldithiocarbamate, zinc di (linear or branched) undecyldithiocarbamate, zinc di (linear or branched) zinc dodecyldithiocarbamate, di (linear or branched) Zinc tridecyl dithiocarbamate, di (linear or branched), and mixtures thereof, and the like.

As another preferred example of the sulfur-containing antioxidant, molybdenum dialkyldithiocarbamate includes those represented by the following general formula (3).

[0031]

Embedded image

In the general formula (3), R ⁹ , R ¹⁰ , R ¹¹ and R ¹² each independently represent a hydrocarbon group having 1 to 18 carbon atoms, such as a methyl group ,
Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, linear or branched pentyl group, linear or branched hexyl group, linear or Branched heptyl, straight or branched octyl, straight or branched nonyl, straight or branched decyl, straight or branched undecyl, straight or branched dodecyl Linear or branched tridecyl group, linear or branched tetradecyl group, linear or branched pentadecyl group, linear or branched hexadecyl group, linear or branched heptadecyl group, linear or branched A C1-C18 alkyl group such as a branched octadecyl group; a linear or branched butenyl group, a linear or branched pentenyl group, a linear or branched hexenyl group, a linear or branched heptenyl group A straight or branched octenyl group, a straight or branched nonenyl group, a straight or branched decenyl group, a straight or branched undecenyl group, a straight or branched dodecenyl group, a straight or branched Branched tridecenyl group, straight or branched tetradecenyl group, straight or branched pentadecenyl group, straight or branched hexadecenyl group, straight or branched heptadecenyl group, straight or branched octadecenyl group, etc. An alkenyl group having 4 to 18 carbon atoms; a cycloalkyl group having 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexyl group and a cycloheptyl group; a methylcyclopentyl group, a dimethylcyclopentyl group (including all structural isomers); Cyclopentyl group (including all structural isomers), diethylcyclopentyl group (including all structural isomers), methyl Cyclohexyl, dimethylcyclohexyl (including all structural isomers), methylethylcyclohexyl (including all structural isomers), diethylcyclohexyl (including all structural isomers), methylcycloheptyl, dimethylcyclo Alkylcyclo having 6 to 11 carbon atoms such as a heptyl group (including all structural isomers), a methylethylcycloheptyl group (including all structural isomers), and a diethylcycloheptyl group (including all structural isomers). Alkyl groups; aryl groups such as phenyl and naphthyl groups; tolyl groups (including all structural isomers), xylyl groups (including all structural isomers), ethylphenyl groups (including all structural isomers), Straight or branched propylphenyl group (including all structural isomers), straight or branched butylphenyl group (all ), A linear or branched pentylphenyl group (including all structural isomers), a linear or branched hexylphenyl group (including all structural isomers), a linear or branched A branched heptylphenyl group (including all structural isomers), a linear or branched octylphenyl group (including all structural isomers), a linear or branched nonylphenyl group (including all structural isomers) Straight chain or branched decylphenyl groups (including all structural isomers),
Each alkylaryl group having 7 to 18 carbon atoms such as a linear or branched undecylphenyl group (including all structural isomers) and a linear or branched dodecylphenyl group (including all structural isomers) A benzyl group, a phenylethyl group,
Phenylpropyl group (including isomer of propyl group), phenylbutyl group (including isomer of butyl group), phenylpentyl group (including isomer of pentyl group), phenylhexyl group (including isomer of hexyl group) 7)
To 12 arylalkyl groups.

The above-mentioned alkyl group or alkenyl group may be a so-called primary alkyl group or alkenyl group in which the carbon atom at the portion bonded to the nitrogen atom is a primary carbon, and the carbon atom is a secondary carbon atom. It may be a so-called secondary alkyl group or alkenyl group, or a tertiary alkyl or alkenyl group in which the carbon atom is tertiary.

Among the compounds represented by the general formula (3),
Molybdenum dialkyldithiocarbamate in which R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently an alkyl group having 4 to 13 carbon atoms is particularly preferred in terms of providing a lubricating oil composition having high oxidation stability.

X ¹ , X ² , X in the above formula (3)
³ and X ⁴ each independently represent a sulfur atom or an oxygen atom, but X ¹ , X ² , X
Preferably, at least one of ³ and X ⁴ is a sulfur atom.

In the present invention, two or more molybdenum dialkyldithiocarbamates included in the general formula (3) may be used in a mixture at an arbitrary ratio. And in this case, the general formula (3) atomic groups shown below in the average structure of _{(A) -Mo 2 SaO (x} -a) - when expressed in, a is preferably from 1 to 3, more Preferably 1.
The use of a molybdenum dialkyldithiocarbamate mixture having a ratio of 5 to 2.5 is preferred in view of oxidation stability and stability against bearing corrosion.

[0037]

Embedded image

[0038] X ^1, X ^2, X ³ and X ⁴ in the atomic group (A) shows X ¹ in the general formula ^{(3), X 2, X} 3 and X ^4, respectively.

Particularly preferred examples of molybdenum dihydrocarbyl dithiocarbamate include, for example, molybdenum di (linear or branched) butyldithiocarbamate, molybdenum di (linear or branched) pentyldithiocarbamate, molybdenum sulfide, Chain or branched) molybdenum sulphide hexyl dithiocarbamate, molybdenum sulphide di (linear or branched) heptyl dithiocarbamate,
Molybdenum di (straight or branched) octyl dithiocarbamate, molybdenum di (linear or branched) nonyldithiocarbamate, molybdenum di (linear or branched) decyldithiocarbamate, di (linear or branched) Molybdenum sulfide undecyldithiocarbamate, molybdenum di (linear or branched) dodecyldithiocarbamate, molybdenum di (linear or branched) tridecyldithiocarbamate, oxymolybdenum sulfide di (linear or branched) butyldithiocarbamate, di Oxymolybdenum sulfide (straight or branched) pentyl dithiocarbamate, oxymolybdenum sulfide di (linear or branched) hexyldithiocarbamate, oxymolybdenum sulfide (di (linear or branched) heptyl dithiocarbamate, di (linear or branched) Branch) octyljichi Oxymolybdenum sulfide carbamate, di (linear or branched) nonyldithiocarbamate oxymolybdenum sulfide, di (linear or branched) decyldithiocarbamate oxymolybdenum sulfide, di (linear or branched) undecyldithiocarbamate oxysulfide Molybdenum, oxymolybdenum di (linear or branched) dodecyldithiocarbamate, oxymolybdenum di (linear or branched) tridecyldithiocarbamate, and mixtures thereof can be mentioned.

Examples of the sulfides which are other suitable examples of the sulfur-containing antioxidant include, for example, dihydrocarbyl polysulfide represented by the following general formula (4).

R ¹³ —S _a —R ¹⁴ General formula (4)

In the formula, R ¹³ and R ¹⁴ may be the same or different and each is a straight-chain or branched alkyl group having 1 to 22 carbon atoms, an aryl group having 6 to 20 carbon atoms, and a carbon atom having 7 carbon atoms. To 20 alkylaryl groups, or 7 to 2 carbon atoms
Represents an arylalkyl group of 0, and a represents 1 to 5, preferably 1 to 2, and more preferably 2.

Specific examples of R ¹³ and R ¹⁴ include methyl, ethyl, n-propyl, isopropyl, n-
Butyl group, isobutyl group, sec-butyl group, tert
-Butyl group, linear or branched pentyl group, linear or branched hexyl group, cyclohexyl group, linear or branched heptyl group, linear or branched octyl group (such as tert-octyl group), linear or branched Branched nonyl group, straight or branched decyl group, straight or branched undecyl group, straight or branched dodecyl group (tert-dodecyl group, etc.), straight or branched tridecyl group, straight or branched tetradecyl group Linear or branched pentadecyl group, linear or branched hexadecyl group (2-methylpentadecyl group, tert-hexadecyl group, etc.), linear or branched heptadecyl group, linear or branched octadecyl group, linear or branched A branched nonadecyl group,
Alkyl groups such as linear or branched icosyl groups, linear or branched henicosyl groups, linear or branched docosyl groups; alkenyl groups such as propenyl group and butenyl group; phenyl groups and naphthyl groups (including all isomers) Aryl groups such as tolyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, Dodecylphenyl group, xylyl group, ethylmethylphenyl group, diethylphenyl group, dipropylphenyl group, dibutylphenyl group, methylnaphthyl group, ethylnaphthyl group, propylnaphthyl group, butylnaphthyl group, dimethylnaphthyl group, ethylmethylnaphthyl group, Diethylnaphthyl group, di Ropirunafuchiru group, alkylaryl group, such as Jibuchirunafuchiru group (the alkyl portions of these alkylaryl groups may be linear or branched, substituted position on the aryl group in the alkyl moiety is optional.);
And arylalkyl groups such as a benzyl group, a phenethyl group and a phenylpropyl group (the alkyl portion of these arylalkyl groups may be linear or branched, and the substitution position of the aryl portion is arbitrary).

Among the specific examples of R ¹³ and R ¹⁴ , C 3-18 alkyl groups derived from propylene or isobutene; C 6-8 aryl groups; C 7-8 alkyl An aryl group; or an arylalkyl group having 7 to 8 carbon atoms is preferable. These groups include, for example, an isopropyl group, a branched hexyl group derived from a propylene dimer, a branched nonyl group derived from a propylene trimer, and a branched dodecyl derived from a propylene tetramer. Pentadecyl group derived from propylene pentamer, branched octadecyl group derived from propylene hexamer, tert-butyl group, branched octyl group derived from isobutene dimer, isobutene Alkyl groups such as a branched dodecyl group derived from a trimer, a branched hexadecyl group derived from an isobutene tetramer (these alkyl groups include all branched isomers); a propenyl group, Alkenyl group such as butenyl group; alkylaryl group such as phenyl group, tolyl group, ethylphenyl group, xylyl group (of these alkylaryl groups) The alkyl moiety may be linear or branched, and the substitution position of the alkyl moiety on the aryl group is arbitrary.); And arylalkyl such as benzyl group and phenylethyl group (the substitution position of the phenyl group is arbitrary). Groups. Among them, an alkyl group having 3 to 18 carbon atoms, particularly 6 to 15 carbon atoms, derived from propylene or isobutene is particularly preferred.

Specific examples of dihydrocarbyl polysulfide include dimethyl polysulfide such as dimethyl monosulfide and dimethyl disulfide; diethyl polysulfide such as diethyl monosulfide and diethyl disulfide; and di-n-propyl monosulfide and di-n-propyl disulfide. Di-n-propyl polysulfide; diisopropyl polysulfide such as diisopropyl monosulfide and diisopropyl disulfide; di-n-butyl polysulfide such as di-n-butyl monosulfide and di-n-butyl disulfide; diisobutyl monosulfide and diisobutyl disulfide Diisobutyl polysulfide; dise
disec-butyl polysulfide such as c-butyl monosulfide and disec-butyl disulfide; di-t
di (tert-butyl polysulfide) such as tert-butyl monosulfide, di-tert-butyl disulfide; di (linear or branched pentyl) monosulfide;
Di (linear or branched pentyl) disulfide, such as di (linear or branched pentyl) disulfide; di (linear or branched hexyl) monosulfide, di (linear or branched hexyl) disulfide, etc. (Linear or branched hexyl) polysulfide; dicyclohexyl polysulfide such as dicyclohexyl monosulfide, dicyclohexyl disulfide; di (linear or branched heptyl) monosulfide, di (linear or branched heptyl) disulfide and the like. Chain or branched heptyl) polysulfide; ditert-octyl polysulfide such as ditert-octyl monosulfide, ditert-octyl disulfide; di (linear or branched octyl) monosulfide, di (linear or branched octyl) Disulph Di etc. id (straight or branched octyl) polysulfide; di- (straight or branched nonyl)
Di (linear or branched nonyl) polysulfides such as monosulfide, di (linear or branched nonyl) disulfide; di (linear or branched decyl) monosulfide;
Di (linear or branched decyl) disulfide, such as di (linear or branched undecyl) polysulfide; di (linear or branched undecyl) monosulfide, di (linear or branched undecyl) disulfide, etc. (Linear or branched undecyl) polysulfide; ditert-dodecyl polysulfide such as ditert-dodecyl monosulfide, ditert-dodecyl disulfide; di (linear or branched dodecyl) monosulfide, di (linear or branched) Di (linear or branched dodecyl) polysulfides such as dodecyl) disulfide; di (linear or branched tridecyl) such as di (linear or branched tridecyl) monosulfide, di (linear or branched tridecyl) disulfide ) Polysulfide; di (linear or branched tetradecyl) monosa Di (linear or branched tetradecyl) disulfide such as fido, di (linear or branched tetradecyl) disulfide; di (linear or branched pentadecyl) monosulfide, di (linear or branched pentadecyl) disulfide and the like (Straight or branched pentadecyl) polysulfide; di-2-methylpentadecyl polysulfide such as di-2-methylpentadecyl monosulfide, di-2-methylpentadecyl disulfide; ditert-hexadecylmonosulfide, ditert- Ditert, such as hexadecyl disulfide
Hexadecyl polysulfide; di (linear or branched hexadecyl) monosulfide, di (linear or branched hexadecyl) disulfide, etc. di (linear or branched hexadecyl) polysulfide; di (linear or branched heptadecyl) Di (linear or branched heptadecyl) polysulfides, such as monosulfide, di (linear or branched heptadecyl) disulfide; di (linear or branched octadecyl) monosulfide, di (linear or branched octadecyl) disulfide Di (linear or branched nonadecyl) monosulfide; di (linear or branched nonadecyl) disulfide; di (linear or branched nonadecyl) disulfide; di (linear or branched nonadecyl) polysulfide; (Straight or branched icosyl) monosulfur De, di (straight or branched eicosyl)
Di (linear or branched heicosyl) polysulfides such as disulfide; di (linear or branched henicosyl) polysulfides such as di (linear or branched henicosyl) monosulfide, di (linear or branched henicosyl) disulfide Di (linear or branched docosyl) monosulfide, di (linear or branched docosyl) disulfide and the like; di (linear or branched docosyl) polysulfide; dipropenyl such as dipropenyl monosulfide and dipropenyl disulfide; Polysulfide; dibutenyl polysulfide such as dibutenyl monosulfide and dibutenyl disulfide; diphenyl polysulfide such as diphenyl monosulfide and diphenyl disulfide; dinaphthyl monosulfide and dinaphthyl disulfide. Naphthyl polysulfide; ditolyl polysulfide such as ditolyl monosulfide and ditolyl disulfide; diethylphenyl polysulfide such as diethylphenyl monosulfide and diethylphenyl disulfide; dipropylphenyl polysulfide such as dipropylphenyl monosulfide and dipropylphenyl disulfide; dibutyl Dibutyl phenyl polysulfide such as phenyl monosulfide and dibutyl phenyl disulfide; dipentyl phenyl polysulfide such as dipentyl phenyl monosulfide and dipentyl phenyl disulfide; dihexyl phenyl polysulfide such as dihexyl phenyl monosulfide and dihexyl phenyl disulfide; diheptyl phenyl monosulfide , Diheptyl phenyl polysulfide such as diheptyl phenyl disulfide; dioctyl phenyl polysulfide such as dioctyl phenyl monosulfide and dioctyl phenyl disulfide; dinonyl phenyl polysulfide such as dinonyl phenyl monosulfide and dinonyl phenyl disulfide; didecyl phenyl monosulfide Didecylphenyl polysulfides such as sulfide and didecylphenyl disulfide; diundecylphenyl polysulfides such as diundecylphenyl monosulfide and diundecylphenyl disulfide; didodecylphenyl polysulfides such as didodecylphenyl monosulfide and didodecylphenyl disulfide; Dixylyl monosulfide and dixylyl disulfide Xylyl polysulfide; diethylmethylphenyl polysulfide such as diethylmethylphenyl monosulfide and diethylmethylphenyl disulfide;
Di (diethylphenyl) polysulfide such as di (diethylphenyl) monosulfide and di (diethylphenyl) disulfide; di (dipropylphenyl) polysulfide such as di (dipropylphenyl) monosulfide and di (dipropylphenyl) disulfide A di (dibutylphenyl) such as di (dibutylphenyl) monosulfide, di (dibutylphenyl) disulfide;
Polysulfide; dimethylnaphthyl polysulfide such as dimethylnaphthyl monosulfide and dimethylnaphthyl disulfide; diethylnaphthyl polysulfide such as diethylnaphthyl monosulfide and diethylnaphthyl disulfide; dipropylnaphthyl polysulfide such as dipropylnaphthyl monosulfide and dipropylnaphthyldisulfide; Dibutyl naphthyl polysulfide such as dibutyl naphthyl monosulfide and dibutyl naphthyl disulfide; dibenzyl polysulfide such as dibenzyl monosulfide and dibenzyl disulfide; diphenethyl polysulfide such as diphenethyl monosulfide and diphenethyl disulfide; diphenylpropyl monosulfide; Diphenylpropyldisal Diphenylpropyl polysulfide, and mixtures thereof, such as Aido and the like.

As other compounds of the sulfides, there may be mentioned diester polysulfides represented by the following general formula (5).

R ¹⁵ OCO (CH ₂ ) _b S _c (CH ₂ ) _d COOR ¹⁶ General formula (5)

In the formula, R ¹⁵ and R ¹⁶ may be the same or different and each have 2 to 20 carbon atoms, preferably 4 to 20 carbon atoms.
20 linear or branched alkyl groups are represented by b and d
May be the same or different and each represents 2 to 5, preferably 2, and c represents 1 to 2, preferably 1.

Specific examples of R ¹⁵ and R ¹⁶ include an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group,
Isobutyl group, sec-butyl group, tert-butyl group, linear or branched pentyl group, linear or branched hexyl group, linear or branched heptyl group, linear or branched octyl group, linear or branched Nonyl group, straight or branched decyl group, straight or branched undecyl group, straight or branched dodecyl group, straight or branched tridecyl group, straight or branched tetradecyl group, straight or branched pentadecyl group A straight-chain or branched hexadecyl group, a straight-chain or branched heptadecyl group, a straight-chain or branched octadecyl group, a straight-chain or branched nonadecyl group, a straight-chain or branched icosyl group.

Specific examples of diester polysulfide include C ₄ H ₉ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ COO
C ₄ H ₉ , C ₄ H ₉ OCO (CH ₂ ) ₂ S ₂ (CH ₂ )
₂ COOC ₄ H ₉ , C ₅ H ₁₁ OCO (CH ₂ ) ₂ S (C
_{H 2) 2 COOC 5 H 11} , C 5 H 11 OCO (CH 2) 2
_{S 2 (CH 2) 2 COOC} 5 H 11, C 6 H 13 OCO (C
H ₂ ) ₂ S (CH ₂ ) ₂ COOC ₆ H ₁₃ , C ₆ H ₁₃ OC
O (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC ₆ H ₁₃ , C ₇
H ₁₅ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ COOC ₇
H ₁₅ , C ₇ H ₁₅ OCO (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ C
OOC ₇ H ₁₅ , C ₈ H ₁₇ OCO (CH ₂ ) ₂ S (CH
₂ ) ₂ COOC ₈ H ₁₇ , C ₈ H ₁₇ OCO (CH ₂ ) ₂ S
₂ (CH ₂ ) ₂ COOC ₈ H ₁₇ , C ₉ H ₁₉ OCO (CH
₂ ) ₂ S (CH ₂ ) ₂ COOC ₉ H ₁₉ , C ₉ H ₁₉ OCO
(CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC ₉ H ₁₉ , C ₁₀ H
₂₁ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ COOC ₁₀ H ₂₁ ,
C ₁₀ H ₂₁ OCO (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC
₁₀ H ₂₁ , C ₁₁ H ₂₃ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ C
OOC ₁₁ H ₂₃ , C ₁₁ H ₂₃ OCO (CH ₂ ) ₂ S ₂ (CH
_{2) 2 COOC 11 H 23,} C 12 H 25 OCO (CH 2) 2 S
(CH ₂ ) ₂ COOC ₁₂ H ₂₅ , C ₁₂ H ₂₅ OCO (CH
₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC ₁₂ H ₂₅ , C ₁₃ H ₂₇ OC
O (CH ₂ ) ₂ S (CH ₂ ) ₂ COOC ₁₃ H ₂₇ , C ₁₃ H
₂₇ OCO (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC
₁₃ H ₂₇ , C ₁₄ H ₂₉ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ C
OOC ₁₄ H ₂₉ , C ₁₄ H ₂₉ OCO (CH ₂ ) ₂ S ₂ (CH
_{2) 2 COOC 14 H 29,} C 15 H 31 OCO (CH 2) 2 S
_{(CH 2) 2 COOC 15 H} 31, C 15 H 31 OCO (CH
₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC ₁₅ H ₃₁ , C ₁₆ H ₃₃ OC
O (CH ₂ ) ₂ S (CH ₂ ) ₂ COOC ₁₆ H ₃₃ , C ₁₆ H
₃₃ OCO (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC
_{16 H 33, C 17 H 35} OCO (CH 2) 2 S (CH 2) 2 C
OOC ₁₇ H ₃₅ , C ₁₇ H ₃₅ OCO (CH ₂ ) ₂ S ₂ (CH
₂ ) ₂ COOC ₁₇ H ₃₅ , C ₁₈ H ₃₇ OCO (CH ₂ ) ₂ S
_{(CH 2) 2 COOC 18 H} 37, C 18 H 37 OCO (CH
_{2) 2 S 2 (CH 2} ) 2 COOC 18 H 37, C 19 H 39 OC
O (CH ₂ ) ₂ S (CH ₂ ) ₂ COOC ₁₉ H ₃₉ , C ₁₉ H
₃₉ OCO (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC
₁₉ H ₃₉ , C ₂₀ H ₄₁ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ C
OOC ₂₀ H ₄₁ , C ₂₀ H ₄₁ OCO (CH ₂ ) ₂ S ₂ (CH
_{2) 2} COOC ₂₀ H ₄₁ or a mixture thereof.

As other compounds of sulfides, there can be mentioned tetraester tetrasulfide represented by the following general formula (6).

(R ¹⁷ SCH ₂ CH ₂ COOCH ₂ ) ₄ C General Formula (6)

In the formula, R ¹⁷ represents a linear or branched alkyl group having 8 to 20, preferably 10 to 18 carbon atoms.
Specific examples of R ¹⁷ include a straight or branched octyl group, a straight or branched nonyl group, a straight or branched decyl group, a straight or branched undecyl group, a straight or branched dodecyl group, a straight or branched dodecyl group, Branched tridecyl, straight or branched tetradecyl, straight or branched pentadecyl, straight or branched hexadecyl, straight or branched heptadecyl, straight or branched octadecyl, straight or branched Examples include a nonadecyl group, a linear or branched icosyl group, and a linear or branched dodecyl group and a linear or branched tridecyl group are particularly preferable.

Specific examples of tetraester tetrasulfide include (C ₈ H ₁₇ SCH ₂ CH ₂ COOCH ₂ ) ₄
C, (C ₉ H ₁₉ SCH ₂ CH ₂ COOCH ₂ ) ₄ C,
(C ₁₀ H ₂₁ SCH ₂ CH ₂ COOCH ₂ ) ₄ C, (C _{11
H 23 SCH 2 CH 2 COOCH 2} ) 4 C, (C 12 H 25 S
CH ₂ CH ₂ COOCH ₂ ) ₄ C, (C ₁₃ H ₂₇ SCH ₂
CH ₂ COOCH ₂ ) ₄ C, (C ₁₄ H ₂₉ SCH ₂ CH ₂
COOCH ₂ ) ₄ C, (C ₁₅ H ₃₁ SCH ₂ CH ₂ COO
CH ₂ ) ₄ C, (C ₁₆ H ₃₃ SCH ₂ CH ₂ COOCH
₂ ) ₄ C, (C ₁₇ H ₃₅ SCH ₂ CH ₂ COOCH ₂ ) ₄
C, (C ₁₈ H ₃₇ SCH ₂ CH ₂ COOCH ₂ ) ₄ C,
(C ₁₉ H ₃₉ SCH ₂ CH ₂ COOCH ₂ ) ₄ C, (C ₂₀
H ₄₁ SCH ₂ CH ₂ COOCH ₂ ) ₄ C or a mixture thereof, especially (C ₁₂ H ₂₅ SCH ₂ CH ₂ CO ₂₎
OCH ₂ ) ₄ C is preferred.

In the present invention, the amount of the sulfur-containing antioxidant is at least 0.01 part by weight, preferably at least 0.1 part by weight, and at most 10 parts by weight, preferably at most 5 parts by weight, per 100 parts by weight of the base oil. It is blended in the range. When the compounding amount of the sulfur-containing antioxidant is less than the above 0.01 part by weight, a sufficient antioxidant effect cannot be obtained, which is not preferable, and when the compounding amount of the sulfur-containing antioxidant exceeds the above 10 parts by weight. Is not preferred because abrasion may occur.

The lubricating oil composition of the present invention has excellent oxidative stability by itself, but in order to further enhance these various performances, known lubricating oil additives may be used alone or in combination of several kinds. Can be blended with the lubricating oil composition of the present invention.

Known additives that can be blended include, for example, neutral, basic, calcium carbonate overbased, calcium borate overbased alkaline earth metal sulfonates, alkaline earth metal salicylates, alkaline earth metal Detergents such as phenate; anti-wear agents such as organic phosphates, organic phosphites, fatty acids, fatty acid esters, and fatty alcohols; polybutenyl succinimides, long-chain alkyl polyamines, and amides of long-chain fatty acids and polyamines Or an ashless dispersant such as a boride thereof; an amine-based antioxidant such as phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine and dialkyldiphenylamine; a phenol-based ashless antioxidant; molybdenum dithiophosphate, molybdenum disulfide; Long-chain aliphatic amine, long-chain fatty acid, long Friction reducing agents such as chain fatty acid esters and long chain aliphatic alcohols; Rust inhibitors such as petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinate, polyhydric alcohol ester; polyoxyethylene alkyl ether, polyoxyethylene Alkyl phenyl ether,
Demulsifiers represented by polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl naphthyl ether; imidazoline, pyrimidine derivatives, alkyl thiadiazole, mercaptobenzothiazole,
Benzotriazole or a derivative thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bisdialkyldithiocarbamate, 2
-(Alkyldithio) benzimidazole, β- (o-
Metal deactivators such as carboxybenzylthio) propionnitrile; antifoaming agents such as silicone, fluorosilicone, and fluoroalkyl ether; and viscosity index improvers such as polymethacrylate, olefin copolymer or hydride thereof.

When these additives are added to the lubricating oil composition of the present invention, the amount of addition is 0.0005 to 1 part by weight for the defoaming agent and 100 parts by weight for the lubricating oil composition. The activator is usually selected in the range of 0.005 to 1 part by weight, and the other additives are each usually selected in the range of 0.1 to 15 parts by weight.

The lubricating oil composition of the present invention can be particularly preferably used as a lubricating oil for internal combustion engines such as gasoline engines for two-wheeled vehicles and four-wheeled vehicles, land-based diesel engines, marine diesel engines and the like. Gear oils for automobiles, such as manual transmission oils, differential oils, etc .; industrial gear oils; hydraulic oils; compressor oils; refrigeration oils; cutting oils; It can be used in various applications such as plastic working oils such as heat treatment oils, metal working oils such as electric discharge machining oils, sliding guide surface oils, bearing oils, rust preventive oils, and heat medium oils.

[0060]

EXAMPLES The contents of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

The base oils and additives used are shown below. 1. Base oil (1) Saturated extracted mineral oil 1 Saturated component extracted from solvent refined mineral oil. ^3. Kinematic viscosity at 40 ° C. 20.0 mm ² / s, kinematic viscosity at 100 ° C.
2 mm ² / s, viscosity index 111. (2) Saturated extracted mineral oil 2 Saturated component extracted from solvent refined mineral oil. 4. Kinetic viscosity at 40 ° C. 31.1 mm ² / s, kinematic viscosity at 100 ° C.
4 mm ² / s, viscosity index 109. (3) Aromatic extracted mineral oil An aromatic component extracted from a solvent refined mineral oil. (4) 9,10-dihydroanthracene (5) dodecylbenzene

[0062] 2. Sulfur-containing antioxidant (1) Zinc dialkyldithiophosphate The alkyl group is a mixed alkyl group of a sec-butyl group and a sec-hexyl group. Effective concentration 100% by mass. (2) Molybdenum dioctyl dithiocarbamate Diluted with mineral oil. Effective concentration 30% by mass. (3) dibenzyl disulfide (4) dilauryl thiodipropionate

3. Additive package Contains metal detergents, ashless dispersants, phenolic antioxidants, corrosion inhibitors and friction modifiers.

Examples 1 to 3 A mixture having the composition shown in Table 1 was heated and stirred at a temperature of 80 ° C. for 2 hours to obtain a lubricating oil composition of the present invention. Using a high pressure differential thermal analyzer at a temperature of 20
The oxidation life was measured under the conditions of 0 ° C. and 2 MPa of oxygen pressure.
Table 1 shows the results.

Comparative Examples 1 to 7 Lubricating oil compositions for comparison having the compositions shown in Table 2 were obtained in the same manner as in the examples. The oxidation life was measured in the same manner as in the example. Table 2 shows the results.

[0066]

[Table 1]

[0067]

[Table 2]

The lubricating oil compositions of Examples 1 to 3 all exhibited excellent oxidation stability. On the other hand, Comparative Example 1 containing no aromatic hydrocarbon component, Comparative Example 2 containing more than 97% by mass of the saturated hydrocarbon component in the base oil, and Comparative Example containing less than 70% by mass of the saturated hydrocarbon component in the base oil 3, Comparative Example 4 in which kp [RH] of the aromatic hydrocarbon component exceeds 20 (s ^-1 ), Comparative Example 5 in which kp [RH] of the aromatic hydrocarbon component is less than 1 (s ^-1 ), saturation Kp [RH] of the hydrocarbon component is 0.3
The oxidation stability of Comparative Example 6 exceeding (s ^-1 ) and Comparative Example 7 in which the sulfur-containing antioxidant was not added were not sufficient. As described above, the lubricating oil composition of the present invention does not provide sufficient oxidation stability even if one of the components is out of the range of the present invention, and it is important to satisfy all of these components. is there.

[0069]

The lubricating oil composition of the present invention achieves high oxidation stability, and can be used under more severe conditions than conventional lubricating oils.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C10M 137: 10) C10N 10:04 10:12 20:00 30:08 30:10 40:25 (72) Inventor Hiroshi Kanoya Kanagawa 8 Chidori-cho, Naka-ku, Yokohama-shi

Claims (1)

[Claims] 1. (1) 70-97% by mass of a saturated hydrocarbon component and 2-30% by mass of an aromatic hydrocarbon component,
A base oil having a resin content of 1% by mass or less, wherein kp ¹ [RH] ¹ (kp ¹ (M ⁻¹ s ⁻¹ ) of the saturated hydrocarbon component is 40%
[RH] ¹ (M) represents the average number of moles of the saturated hydrocarbon component in 1 L of the saturated hydrocarbon component at 40 ° C. ) Is 0.3
(S ^-1 ) Hereinafter, kp ² [RH] ^{2 of the} aromatic hydrocarbon component
(Kp ² (M ⁻¹ s ⁻¹ ) is a rate constant of a hydrogen abstraction reaction by a t-butylperoxy radical at 40 ° C.,
[RH] ² (M) represents the average number of moles of the aromatic hydrocarbon component in 1 L of the aromatic hydrocarbon component at 40 ° C., respectively. ) Is 1 to 20 (s ^-1 ).
(2) sulfur-containing antioxidant 0.01 to 0 parts by weight
A lubricating oil composition comprising 10 parts by weight.