JPH1150081A - Lubricating oil composition - Google Patents

Abstract

(57) [Summary] A lubricating oil composition is obtained by adding an antioxidant to a lubricating base oil, and the lubricating base oil contains a saturated hydrocarbon component of 80% by mass or more, and It is a mineral oil-based lubricating oil in which the viscosity-density constant of the saturated hydrocarbon component is 0.79 or less. [Effect] A lubricating oil composition having excellent oxidation stability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition having excellent oxidation stability due to a synergistic effect of a base oil composition and an additive.

[0002]

2. Description of the Related Art Conventionally, lubricating oils have been required to have good oxidation stability. In recent years, with the reduction in the amount of lubricating oil used due to the miniaturization and weight reduction of devices that use lubricating oil, and the increase in the load on lubricating oil locations, lubricating oil has been used under more severe conditions. Was. In particular, lubricating oil in an internal combustion engine is exposed to high temperature parts such as between a piston and a cylinder,
Deterioration by reaction with air and 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 for an internal combustion engine is 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. Also, in the field of industrial lubricating oils, it is necessary to use them for a long period of time without maintenance under severe oxidative deterioration conditions such as air compression oil, steam turbine oil and gas turbine oil.

[0003]

In view of the above, the development of lubricating oils having higher oxidative stability has been desired in recent years. On the other hand, conventionally, lubricating oils based on mineral oils or synthetic oils have been demanded. This has been addressed by adding antioxidants such as hindered phenols, aromatic amines and zinc dithiophosphate to the oil, but this alone was not sufficient. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lubricating oil composition having higher oxidation stability.

[0004]

The present inventors have studied the effects of a base oil composition and an antioxidant on the oxidation stability of a lubricating oil composition containing an antioxidant. The present inventors have found that by using an antioxidant in combination with a base oil, extremely high oxidation stability can be obtained due to a synergistic effect of the two, and have completed the present invention. That is, the lubricating oil composition of the present invention is a lubricating oil composition obtained by adding an antioxidant to a lubricating oil base oil, wherein the lubricating oil base oil contains a saturated hydrocarbon component at 80% by mass or more, and And a mineral oil-based lubricating oil wherein the viscosity-density constant of the saturated hydrocarbon component is 0.79 or less.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the contents of the present invention will be described in more detail. The base oil (component (A)) in the lubricating oil composition of the present invention contains a saturated hydrocarbon component at 80% by mass or more, and a mineral oil having a viscosity-density constant of 0.79 or less of the saturated hydrocarbon component. It is a lubricating oil. The mineral oil-based lubricating base oil of the component (A) contains a saturated hydrocarbon component in an amount of 80% by mass or more, preferably 90% by mass or more (90 to 100% by mass), and more preferably 95% by mass or more (95 to 100% by mass).
% By mass). When the content of the saturated hydrocarbon component of the component (A) is less than 80% by mass, a lubricating oil composition having sufficient oxidation stability cannot be obtained, which is not preferable. The content of the saturated hydrocarbon component as used herein refers to Analytical Chemistry No. 44.
Vol. 6, No. 1972 (pp. 915-919) "Separ
ation of High-Boiling Pet
roleum Distilates Using
Gradient Elution Through
Dual-Packed (Silica Gel-Al
umina Gel) Adsorption Col
umns ", except that n-hexane is used instead of n-pentane used for eluting the saturated hydrocarbon component in this method. The mineral oil-based lubricating base oil of the component (A) used in the present invention means the saturated hydrocarbon component further fractionated by the above method. It is necessary that the base oil has a viscosity-density constant of 0.79 or less, preferably 0.785 or less.
When the ratio exceeds, it is not preferable because a lubricating oil composition having sufficient oxidation stability cannot be obtained. The lower limit of the viscosity-density constant of the saturated hydrocarbon component is arbitrary, but is usually 0.76 or more. The viscosity-density constant referred to herein is ASTM D2140 “Standard”.
Test Method for Carbon-Ty
pe Composition of Insulat
ing Oils of Petroleum Ori
gin ”according to the viscosity-specific gravity constant calculation method described in
Where the density at 15 ° C. instead of the specific gravity at 60 ° F. (15.6 ° C.) was calculated using the kinematic viscosity at 40 ° C. instead of the kinematic viscosity at 100 ° F. (37.8 ° C.). Means. That is, the viscosity-density constant in the present invention means that G is the density at 15 ° C. (g / cm
³ ) When V is the kinematic viscosity at 40 ° C. (mm ² / s), it means a value calculated by the following equation (a). Viscosity-density constant = [G + 0.0887-0.776 log (log (10V-4))] / [1.082-0.72log (log (10V-4))] (a)

The method for producing the mineral lubricating base oil, which is the component (A) of the present invention, is not particularly limited. For example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and vacuum distillation may be used as a solvent. Paraffin based on single or a combination of two or more purification processes such as degreasing, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, hydrorefining, sulfuric acid washing, clay treatment,
Oils such as naphthenic oils can be used. These base oils may be used alone or in combination of two or more kinds at an arbitrary ratio. Further, as a more preferable production method of the component (A) in the present invention, the following method can be mentioned. For example, a distillate obtained by atmospheric distillation of a paraffin-based crude oil and / or a mixed-base crude oil; a vacuum distillation distillate (WVGO) of an atmospheric-distillation residual oil of a paraffin-based crude oil and / or a mixed-base crude oil; And / or mild hydrocracking (MHC) treated oil (HIX); a mixed oil of two or more oils selected from the following; or deoiled oil (DAO); A mixed oil of two or more oils selected from the group consisting of a raw oil, a raw oil, and a lubricating oil fraction recovered from the raw oil, which is refined by an ordinary refining method and lubricated. The component (A) can be obtained by collecting the oil fraction. The ordinary refining method mentioned here is not particularly limited, and any refining method used in producing a lubricating base oil can be adopted. Usual refining methods include, for example, (1) hydrotreating such as hydrocracking and hydrofinishing, (2) solvent refining such as furfural solvent extraction, and (3) dewaxing such as solvent dewaxing and catalytic dewaxing. (4) Purification of clay with acid clay or activated clay, (5) Purification of chemicals (acid or alkali) such as washing with sulfuric acid and caustic soda. In the present invention, one or more of these may be employed in any combination and in any order. In particular, as the mineral oil-based lubricating base oil of the component (A) referred to in the present invention, a raw oil selected from the above (1) or a lubricating oil fraction recovered from this raw oil is hydrocracked, and Recover the lubricating oil fraction as is or from the product,
Next, dewaxing treatment such as solvent dewaxing and contact dewaxing is performed,
Thereafter, the solvent is subjected to a solvent refining treatment or, after the solvent refining treatment, a component produced by performing a dewaxing treatment such as solvent dewaxing or contact dewaxing, preferably at least 50% by mass, based on the total amount of the base oil, It is desirable to use 70% by mass or more, particularly preferably 80% by mass or more.

The kinematic viscosity at 40 ° C. of the component (A) used in the present invention is not particularly limited.
The kinematic viscosity at ° C. is preferably 5 mm ² / s or more, more preferably 10 mm ² / s or more. Its kinematic viscosity at 40 ° C. is preferably 20
It is desirable that it is 0 mm ² / s or less, more preferably 100 mm ² / s or less. By setting the kinematic viscosity at 40 ° C. of the component (A) to 5 mm ² / s or more, a lubricating oil composition that forms an oil film sufficiently, has excellent lubricity, and has a small evaporation loss of the base oil under high temperature conditions. Things can be obtained. On the other hand, by setting the kinematic viscosity at 40 ° C. of the component (A) to 200 mm ² / s or less, the fluid resistance becomes small, so that a lubricating oil composition having a small friction resistance at a lubricated portion can be obtained. The kinematic viscosity at 100 ° C. of the component (A) is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably 0.1 kg / ml.
It is desirable to be at least 5 mm ² / s, more preferably at least 1 mm ² / s. The kinematic viscosity at 100 ° C. is preferably 100 mm ² / s or less, more preferably 50 mm ² / s or less. By setting the kinematic viscosity at 100 ° C. of the component (A) to 0.5 mm ² / s or more, a lubricating oil film is formed sufficiently, the lubricating property is excellent, and the evaporation loss of the base oil under a high temperature condition is small. It becomes possible to obtain an oil composition. On the other hand, by setting the kinematic viscosity at 100 ° C. of the component (A) to 100 mm ² / s or less, the fluid resistance is reduced, so that it is possible to obtain a lubricating oil composition having a smaller friction resistance at a lubricating point. The viscosity index of the component (A) is not particularly limited, but is preferably 50 or more, more preferably 80 or more. By setting the viscosity index of the component (A) to 50 or more, it becomes possible to obtain a lubricating oil composition that can achieve both an oil film forming ability and a fluid resistance reducing ability. The pour point of the component (A) is not particularly limited, but is preferably 0 ° C or lower, more preferably -5 ° C or lower. By setting the pour point of the component (A) to 0 ° C. or lower, it becomes possible to obtain a lubricating oil composition that does not hinder the movement of the machine at low temperatures.

On the other hand, the antioxidant (component (B)) in the lubricating oil composition of the present invention is not particularly limited, but is preferably selected from a hindered phenol type, an aromatic amine type and a sulfur type. And at least one antioxidant. As the hindered phenol-based antioxidant, any hindered phenol-based compound used as an antioxidant for lubricating oil can be used and is not particularly limited. However, specifically preferred compounds include one compound selected from the compounds represented by the following general formula (1) or a mixture of two or more compounds.

Embedded image (1) In the formula, R ¹ and R ² are each independently an alkyl group having 1 to 4 carbon atoms, and at least 1
One is a tert-butyl group. As R ¹ and R ² , specifically, a methyl group, an ethyl group,
Examples of n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group and the like can be given, but one of R ¹ and R ² is a tert-butyl group, and the other is Methyl group, ethyl group or te
It is preferably an rt-butyl group. R ³ is
An alkyl group having 1 to 4 carbon atoms and the following general formula (2):
One group selected from the groups represented by (3) and (4) is shown.

Embedded image

Embedded image

Embedded image Specific examples of the alkyl group having 1 to 4 carbon atoms representing R ³ 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 and a tert-butyl group. Although a group etc. can be illustrated, a methyl group or an ethyl group is more preferable in view of excellent oxidation stability. Among the hindered phenol compounds represented by the general formula (1), particularly preferred as a compound wherein R ³ is an alkyl group having 1 to 4 carbon atoms is 2,6-di-t.
tert-butyl-p-cresol, 2,6-di-ter
t-butyl-4-ethylphenol and mixtures thereof, and the like.

In the group represented by the general formula (2), R ⁴ represents an alkylene group having 1 to 6 carbon atoms, and R ⁵ represents an alkyl group or an alkenyl group having 1 to 24 carbon atoms. . The alkylene group having 1 to 6 carbon atoms represented by R ⁴ may be linear or branched. Specifically, a methylene group, a methylmethylene group, an ethylene group (dimethylene group), an ethylmethylene group, a propylene group (methylethylene group), a trimethylene group, a linear or branched butylene group, a linear or branched pentylene group Examples thereof include a group, a linear or branched hexylene group, and among them, an alkylene group having 1 to 2 carbon atoms, specifically, a methylene group, a methylmethylene group, and an ethylene group (dimethylene group) are more preferable. On the other hand, carbon number 1 to 1 represented by R ⁵
The 24 alkyl groups or alkenyl groups may be linear or branched. Specific examples of R ⁵ 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 group. Pentyl group, linear or branched hexyl group, linear or branched heptyl group, linear or branched octyl group, linear or branched nonyl group, linear Linear or branched decyl group, linear or branched undecyl group, linear or branched dodecy group, 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 octadecyl group, linear Or branched nonadecyl group, straight or branched Alkyl such as an isosyl group, a linear or branched henicosyl group, a linear or branched docosyl group, a linear or branched tricosyl group, a linear or branched tetracosyl group Groups; vinyl, propenyl, isopropenyl, linear or branched butenyl, linear or branched pentenyl, linear or branched hexenyl, linear or branched A 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, Linear or branched dodecenyl group, linear or branched tridecenyl group, linear or branched tetradecenyl group, linear or branched pentadecenyl group, linear or branched Hexadecenyl group, straight chain Linear or branched heptadecenyl group, linear or branched octadecenyl group, linear or branched octadecadienyl group, linear or branched nonadecenyl group, linear or branched A branched icosenyl group, a straight or branched henicocenyl group, a straight or branched docosenyl group, a straight or branched tricosenyl group, a straight or branched tetracosenyl group, etc. Alkenyl group; and the like. Still R ^5, from the viewpoint of solubility is excellent for lubricating base oils, carbon atoms from 4 to 18
Alkyl group, specifically, for example, 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, linear or branched decyl group, linear or branched Linear undecyl group, linear or branched dodecyl group, linear or branched tridecyl group, linear or branched tetradecyl group, linear or branched pentadecyl group, Alkyl groups such as a linear or branched hexadecyl group, a linear or branched heptadecyl group, and a linear or branched octadecyl group are preferable, and among these, a linear group having 6 to 12 carbon atoms. Or a branched alkyl group is more preferred, Branched alkyl groups of primes 6-12 are particularly preferred. In the group represented by the general formula (2), those in which R ⁴ is an alkylene group having 1 to 2 carbon atoms and R ⁵ is a linear or branched alkyl group having 6 to 12 carbon atoms are more preferable. Preferably, R ⁴ is an alkylene group having 1 to 2 carbon atoms, and R ⁵ is a branched alkyl group having 6 to 12 carbon atoms. Among the hindered phenol compounds represented by the general formula (1), those particularly preferred as the compounds wherein R ³ is a group represented by the general formula (2) include, specifically, (3-methyl- N-hexyl 5-tert-butyl-4-hydroxyphenyl) acetate, (3-
Isohexyl methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-tert-
Butyl-4-hydroxyphenyl) n-heptyl acetate;
Isoheptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-te
n-octyl tert-butyl-4-hydroxyphenyl) acetate, isooctyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5
-Tert-butyl-4-hydroxyphenyl) acetic acid 2
-Ethylhexyl, n-nonyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-
Isononyl methyl-5-tert-butyl-4-hydroxyphenyl) acetate, n-decyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3
-Methyl-5-tert-butyl-4-hydroxyphenyl) isodecyl acetate, (3-methyl-5-tert-
N-undecyl butyl-4-hydroxyphenyl) acetate, isoundecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5
-Tert-butyl-4-hydroxyphenyl) acetic acid n
-Dodecyl, (3-methyl-5-tert-butyl-4
-Hydroxyphenyl) isododecyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl)
N-hexyl propionate, (3-methyl-5-ter
t-butyl-4-hydroxyphenyl) isohexyl propionate, (3-methyl-5-tert-butyl-4)
-Hydroxyphenyl) n-heptyl propionate,
(3-methyl-5-tert-butyl-4-hydroxyphenyl) isoheptyl propionate, (3-methyl-
N-octyl 5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-
Isooctyl butyl-4-hydroxyphenyl) propionate, 2-ethylhexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate,
N-Nonyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5
-Tert-butyl-4-hydroxyphenyl) propionate isononyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate n-decyl, (3-methyl-5-tert-butyl-4-hydroxy) Phenyl) isodecyl propionate, n-undecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-ter
t-butyl-4-hydroxyphenyl) isoundecyl propionate, (3-methyl-5-tert-butyl-
4-hydroxyphenyl) n-dodecyl propionate,
(3-methyl-5-tert-butyl-4-hydroxyphenyl) isododecyl propionate, (3,5-di-
tert-butyl-4-hydroxyphenyl) acetic acid n-
Hexyl, isohexyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di-t
n-heptyl tert-butyl-4-hydroxyphenyl) acetate, isoheptyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di-te)
n-octyl (rt-butyl-4-hydroxyphenyl) acetate, isooctyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di-ter
2-ethylhexyl (tert-butyl-4-hydroxyphenyl) acetate, n-nonyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di-te)
isononyl (rt-butyl-4-hydroxyphenyl) acetate, n-decyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di-tert-acetate)
Butyl-4-hydroxyphenyl) isodecyl acetate,
N-undecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di-tert-butyl)
Isoundecyl butyl-4-hydroxyphenyl) acetate, n-dodecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di-tert)
-Butyl-4-hydroxyphenyl) isododecyl acetate, n-hexyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-
tert-butyl-4-hydroxyphenyl) isohexyl propionate, (3,5-di-tert-butyl-
4-hydroxyphenyl) n-heptyl propionate,
(3,5-di-tert-butyl-4-hydroxyphenyl) isoheptyl propionate, (3,5-di-te
n-octyl rt-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-)
(Hydroxyphenyl) isooctyl propionate,
2-ethylhexyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, n-nonyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-diphenyl) -Tert-butyl-
4-hydroxyphenyl) isononyl propionate,
N-decyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-ter-
isodecyl (tert-butyl-4-hydroxyphenyl) propionate, n-undecyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,
5-di-tert-butyl-4-hydroxyphenyl)
Isoundecyl propionate, (3,5-di-tert
-Butyl-4-hydroxyphenyl) propionic acid n-
Dodecyl, (3,5-di-tert-butyl-4-hydroxyphenyl) isododecyl propionate, and mixtures thereof can be exemplified.

In the group represented by the general formula (3), R ⁶ represents an alkylene group having 1 to ⁶ carbon atoms, and R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 4 carbon atoms. And at least one of them is a tert-butyl group. Carbon number 1 represented by R ⁶
The alkylene group 6 may be linear or branched, and specific examples of R ⁶ include the various alkylene groups described above as the alkylene group represented by R ^4. Of these, an alkylene group having 1 to 2 carbon atoms, specifically, for example, a methylene group, a methylmethylene group, and an ethylene group (dimethylene group) are more preferable.
On the other hand, the alkyl group having 1 to 4 carbon atoms represented by R ⁷ and R ⁸ may be linear or branched. Specifically, for example, R ¹ and R ² are each independently Examples of the alkyl group shown include various alkyl groups as described above. Among them, one of R ⁷ and R ⁸ is te.
It is preferably an rt-butyl group, and the other is a methyl group, an ethyl group or a tert-butyl group. In the group represented by the general formula (3), R ⁶ has 1 to 2 carbon atoms.
And one of R ⁷ and R ⁸ is tert.
-Butyl group, and the other one is preferably a methyl group, an ethyl group or a tert-butyl group. Among the hindered phenol compounds represented by the general formula (1), particularly preferred compounds as the compounds wherein R ³ is a group represented by the general formula (3) include bis (3,
5-di-tert-butyl-4-hydroxyphenyl)
Methane, 1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) ethane, 1,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) ethane, 1-bis (3,5-di-tert-
Butyl-4-hydroxyphenyl) propane, 1,2-
Bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 1,3-bis (3,5-di-te
rt-butyl-4-hydroxyphenyl) propane,
Examples thereof include 2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane and a mixture thereof.

In the group represented by the general formula (4), R ⁹ and R ¹⁰ each independently represent an alkylene group having 1 to 6 carbon atoms, and R ¹¹ and R ¹² each independently represent a carbon atom. X is an alkyl group of Formulas 1 to 4, and at least one of them is a tert-butyl group;
¹ is an alkylene group or the following formula of 1 to 18 carbon atoms group represented by ^{(5) -R 13 -S-R} 14 - shows a (5), respectively. In the formula (5), R ¹³ and R ¹⁴ each independently represent an alkylene group having 1 to 6 carbon atoms. 1 to 6 carbon atoms represented by R ⁹ and R ¹⁰
The alkylene group of may be linear or branched, and specifically, for example, each independently includes various alkylene groups as described above as the alkylene group represented by R ^4. Among them, separately
An alkylene group having 1 to 2 carbon atoms, specifically, for example, a methylene group, a methylmethylene group, and an ethylene group (dimethylene group) are more preferable. On the other hand, the alkyl group having 1 to 4 carbon atoms represented by R ¹¹ and R ¹² may be linear or branched. Specifically, for example,
Examples of the alkyl group represented by R ¹ and R ² include various alkyl groups as described above.
^It is preferred that one of ¹¹ and R ¹² is a tert-butyl group and the other is a methyl group, an ethyl group or a tert-butyl group. On the other hand, C ¹ to C 18 representing X ¹
Specific examples of the alkylene group include, for example, a methylene group, a methylmethylene group, an ethylene group (dimethylene group),
Ethylmethylene group, propylene group (methylethylene group), trimethylene group, straight or branched butylene group, straight or branched pentylene group, straight or branched hexylene group, straight or branched heptylene group, straight or Branched octylene, straight or branched nonylene, straight or branched decylene, straight or branched undecylene, straight or branched dodecylene, straight or branched tridecylene,
A straight-chain or branched tetradecylene group, a straight-chain or branched pentadecylene group, a straight-chain or branched hexadecylene group, a straight-chain or branched heptadecylene group, a straight-chain or branched octadecylene group, and the like. Alkylene group, specifically, for example, a methylene group, a methylmethylene group, an ethylene group (dimethylene group), an ethylmethylene group,
Propylene group (methylethylene group), trimethylene group,
A straight-chain or branched butylene group, a straight-chain or branched pentylene group, a straight-chain or branched hexylene group, and the like are more preferable,
C2-C6 linear alkylene groups such as ethylene group (dimethylene group), trimethylene group, linear butylene group (tetramethylene group, linear pentylene group (pentamethylene group), linear hexylene group (hexamethylene group)) In addition, in the group represented by the general formula (5) representing X ¹ , the alkylene group having 1 to 6 carbon atoms representing R ¹³ and R ¹⁴ may be linear or branched. Good and specifically, for example, various alkylene groups as described above as the alkylene group represented by R ⁴ , among these, each independently, an alkylene group having 1 to 2 carbon atoms,
Specifically, for example, a methylene group, a methylmethylene group, and an ethylene group (dimethylene group) are more preferable. In the group represented by the general formula (4), R ⁹ and R ¹⁰ are each independently an alkylene group having 1 to 2 carbon atoms, R ¹¹
And one of R ¹² is a tert-butyl group, the other is a methyl group, an ethyl group or a tert-butyl group, and X ¹ is a linear alkylene group having 2 to 6 carbon atoms, or It is a group represented by the formula (5), wherein R ¹³ and R ¹⁴ are each independently an alkylene group having 1 to 2 carbon atoms. General formula (1)
Of the hindered phenol compounds represented by the following formulas, R ³ is particularly preferably a compound represented by the general formula (4), specifically, the following general formulas (6) and (7) And the like.

Embedded image

Embedded image

As the aromatic amine antioxidant which is one of the components (B) in the lubricating oil composition of the present invention, any aromatic amine compound used as an antioxidant for lubricating oil can be used. And is not particularly limited. However, specifically preferred compounds include phenyl-α-naphthylamine, N-alkylphenyl-α-naphthylamine represented by the following general formula (8), and p, one compound selected from p'-dialkyldiphenylamine or 2
Mixtures of more than one compound can be exemplified.

Embedded image

Embedded image In the formula (8), R ¹⁵ represents a linear or branched alkyl group having 1 to 16 carbon atoms. As R ¹⁵ , specifically, a methyl group, an ethyl group, a 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 A pentyl group, a linear or branched hexyl group, a linear or branched heptyl group, a linear or branched octyl group,
Linear or branched nonyl group, linear or branched decyl group, linear or branched undecyl group, linear or branched dodecy group, linear or branched Tridecyl group, linear or branched tetradecyl group, linear or branched pentadecyl group, linear or branched hexadecyl group, and the like. Among them, R ¹⁵
Is preferably a branched alkyl group having 8 to 16 carbon atoms in view of excellent solubility of an oxidation product of itself in a lubricating base oil, and furthermore, a carbon atom derived from an oligomer of an olefin having 3 or 4 carbon atoms. A branched alkyl group of the formulas 8 to 16 is more preferable. Specific examples of the olefin having 3 or 4 carbon atoms include propylene, 1-butene, 2-butene, and isobutylene, which are excellent in solubility of an oxidation product of itself in a lubricating base oil. From, propylene or isobutylene is preferred,
Propylene is more preferred. More specifically, as R ¹⁵ , a branched octyl group derived from a dimer of isobutylene, a branched nonyl group derived from a trimer of propylene,
A branched dodecyl group derived from a trimer of isobutylene,
A branched dodecyl group derived from a propylene tetramer or a branched pentadecyl group derived from a pentamer of propylene is particularly preferred, and a branched dodecyl group derived from a tetramer of propylene or a pentamer of propylene is particularly preferred. Most preferred is a branched pentadecyl group derived from On the other hand, in the formula (9), R ¹⁶ and R ¹⁷ each independently represent a linear or branched alkyl group having 1 to 16 carbon atoms. Specific examples of R ¹⁶ and R ¹⁷ include various alkyl groups as described above as the alkyl group represented by R ¹⁵ , and among these, R ¹⁶ and R ¹⁷ are oxidation products of their own. In view of excellent solubility in a lubricating base oil, a branched alkyl group having 8 to 16 carbon atoms is preferable, and further, a branched alkyl group having 8 to 16 carbon atoms derived from an oligomer of an olefin having 3 or 4 carbon atoms is preferable. Branched alkyl groups are more preferred. As the olefin having 3 or 4 carbon atoms here, specifically, propylene,
Examples thereof include 1-butene, 2-butene, and isobutylene, and propylene or isobutylene is preferable, and propylene is more preferable, since the oxidation product of the compound is excellent in solubility in a lubricating base oil. More specifically,
As R ¹⁶ and R ¹⁷ , a branched octyl group derived from an isobutylene dimer, a branched nonyl group derived from a propylene trimer, a branched dodecyl group derived from an isobutylene trimer, propylene Particularly preferred is a branched dodecyl group derived from a tetramer of propylene or a branched pentadecyl group derived from a pentamer of propylene.
Most preferred are a branched nonyl group derived from a monomer, a branched dodecyl group derived from a propylene tetramer, or a branched pentadecyl group derived from a pentamer of propylene.

As the sulfur-based antioxidant which is one of the components (B) in the lubricating oil composition of the present invention, any sulfur-based compound used as an antioxidant for lubricating oils can be used. It is not limited. However, specifically preferred compounds include metal dihydrocarbyl dithiophosphates such as zinc dihydrocarbyl dithiophosphate and molybdenum dihydrocarbyl; metal such as zinc dihydrocarbyl dithiocarbamate, molybdenum dihydrocarbyl dithiocarbamate, and copper such as copper dihydrocarbyl dithiocarbamate. Dithiocarbamates; one sulfur-based compound selected from sulfides or a mixture of two or more sulfur-based compounds, among which zinc dihydrocarbyl dithiophosphate, zinc dihydrocarbyl dithiocarbamate, and dihydrocarbyl dithiocarbamic acid Molybdenum, sulfides and the like are more preferred. As a preferred example of the sulfur-based antioxidant, zinc dihydrocarbyl dithiophosphate specifically includes a compound represented by the following general formula (10).

Embedded image In the above formula (10), R ¹⁸ , R ¹⁹ , R ²⁰ and R ²¹ each independently represent a hydrocarbon group having 1 to 18 carbon atoms. As such a hydrocarbon group, specifically, a methyl group , Ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, linear or branched pentyl, linear or branched hexyl, linear Or a branched heptyl group, a straight or branched octyl group, a straight or branched nonyl group, a straight or branched decyl group, a 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, 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 linear or branched heptadecenyl group, a linear or branched octadecenyl group; a C 5-7 cycloalkyl group such as a cyclopentyl group, cyclohexyl group, 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 Alkylcycloalkyl groups having 6 to 11 carbon atoms such as diethylcycloheptyl group (including all structural isomers); aryl groups such as phenyl group and naphthyl group: tolyl group (all 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. In addition, the above-mentioned alkyl group or alkenyl group may be a so-called primary alkyl group or alkenyl group in which a carbon atom in a portion bonding to oxygen is a primary carbon, or a so-called secondary carbon atom in which the carbon atom is secondary. May be an alkyl group or an alkenyl group of the formula
It may be a so-called tertiary alkyl or alkenyl group, which is a class. Among the compounds represented by the general formula (10), R ¹⁸ , R ¹⁹ , R ²⁰ and R ²¹ are each independently a linear or branched dialkyldithioline having 1 to 18 carbon atoms. Zinc acid is particularly preferred in that it provides a lubricating oil composition having excellent antioxidant properties. Specific examples of zinc dihydrocarbyl dithiophosphate include zinc diethyldithiophosphate, zinc di-n-propyldithiophosphate, zinc diisopropyldithiophosphate, zinc di-n-butyldithiophosphate, zinc diisobutyldithiophosphate, and disec-
Zinc butyldithiophosphate, zinc ditert-butyldithiophosphate, zinc di (linear or branched pentyl) dithiophosphate, zinc di (linear or branched hexyl) dithiophosphate, di (linear or branched heptyl) dithiophosphate zinc,
Zinc di (straight or branched octyl) dithiophosphate, zinc di (straight or branched nonyl) dithiophosphate, zinc di (straight or branched decyl) dithiophosphate, di (straight or branched undecyl) dithiophosphate Zinc, zinc di (linear or branched dodecyl) dithiophosphate, zinc di (linear or branched tridecyl) dithiophosphate, zinc di (linear or branched tetradecyl) dithiophosphate, di (linear or branched pentadecyl) Zinc dithiophosphate, zinc di (linear or branched hexadecyl) dithiophosphate, zinc di (linear or branched octadecyl) dithiophosphate, zinc diphenyldithiophosphate, zinc diethylphenyldithiophosphate, zinc dipropylphenyldithiophosphate, diisopropylphenyl Zinc dithiophosphate, zinc dibutylphenyldithiophosphate,
Zinc dipentylphenyldithiophosphate, zinc dihexylphenyldithiophosphate, zinc diheptylphenyldithiophosphate, zinc dioctylphenyldithiophosphate, di2-
Zinc ethylhexylphenyldithiophosphate, zinc dinonylphenyldithiophosphate, zinc didecylphenyldithiophosphate, zinc diundecylphenyldithiophosphate, zinc didodecylphenyldithiophosphate, zinc ditridecylphenyldithiophosphate, zinc ditetradecylphenyldithiophosphate, Zinc pentadecylphenyldithiophosphate,
Examples include zinc dihexadecylphenyl dithiophosphate, zinc diheptadecylphenyl dithiophosphate, zinc dioctadecylphenyl dithiophosphate, or a mixture thereof.

As another example of the sulfur-based antioxidant, zinc dihydrocarbyl dithiocarbamate is specifically preferably a compound represented by the following formula (11). .

Embedded image In the above (11), R ²² , R ²³ , R ²⁴ and R ²⁵ each independently represent a hydrocarbon group having 1 to 18 carbon atoms. As R ²² , R ²³ , R ²⁴ and R ²⁵ , specifically, various alkyl groups, alkenyl groups, and the like as described above as the hydrocarbon groups represented by R ¹⁸ , R ¹⁹ , R ²⁰ and R ²¹ Examples thereof include a cycloalkyl group, an alkylcycloalkyl group, an aryl group, an alkylaryl group, and an arylalkyl group. 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 oxygen is a primary carbon, or a so-called secondary carbon atom in which the carbon atom is secondary. Or a tertiary alkyl group or alkenyl group in which the carbon atom is tertiary. Among the compounds represented by the general formula (11), R ²² , R ²³ , R ²⁴ and R ²⁵
However, separately from each other, zinc dialkyldithiocarbamate which is an alkyl group having 4 to 13 carbon atoms is particularly preferable in that a lubricating oil composition having high oxidation stability is provided. Particularly preferred specific examples of zinc dihydrocarbyl dithiocarbamate include, for example, zinc di (linear or branched) butyldithiocarbamate, zinc di (linear or branched) zinc pentyldithiocarbamate, di (linear or branched) Zinc hexyl dithiocarbamate, di (linear or branched)
Zinc heptyldithiocarbamate, zinc di (linear or branched) octyldithiocarbamate, zinc di (linear or branched) nonyldithiocarbamate, zinc di (linear or branched) zinc decyldithiocarbamate, di (linear or branched) Branch) zinc undecyldithiocarbamate, zinc di (linear or branched) zinc dodecyldithiocarbamate, zinc di (linear or branched) zinc tridecyldithiocarbamate, di (linear or branched), and mixtures thereof. Can be mentioned.

As another example of the sulfur-based antioxidant, molybdenum dialkyldithiocarbamate is specifically preferably a compound represented by the following general formula (12).

Embedded image In the above (12), R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ each independently represent a hydrocarbon group having 1 to 18 carbon atoms. As R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ , specifically, various alkyl groups, alkenyl groups, and the like as described above as the hydrocarbon group represented by R ¹⁸ , R ¹⁹ , R ²⁰ and R ²¹ Examples thereof include a cycloalkyl group, an alkylcycloalkyl group, an aryl group, an alkylaryl group, and an arylalkyl group. 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 oxygen is a primary carbon, or a so-called secondary carbon atom in which the carbon atom is secondary. Or a tertiary alkyl group or alkenyl group in which the carbon atom is tertiary. Among the compounds represented by the general formula (12), R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹
However, separately from each other, molybdenum dialkyldithiocarbamate which is an alkyl group having 4 to 13 carbon atoms is particularly preferable in that a lubricating oil composition having high oxidation stability is provided. X ² , X ³ , X ⁴ and X ⁵ in the above general formula (12) each independently represent a sulfur atom or an oxygen atom. However, in order to obtain high oxidation stability, X ² , X ³ ,
It is preferred that at least one of X ⁴ and X ⁵ is a sulfur atom. In the present invention, two or more kinds of molybdenum dihydrocarbyl dithiocarbamates included in the general formula (12) can be used in a mixture at an arbitrary ratio. And in this case, the general formula (12) following general formula (13) -Mo ₂ the average structure of the atomic group indicated by S _a O in
_When represented by _(4-a) -, it is possible to use a mixture of molybdenum dihydrocarbyl dithiocarbamates in which a is preferably 1 to 3, more preferably 1.5 to 2.5. It is preferable in terms of stability against corrosion.

Embedded image X ² , X ³ , X in the above atomic group (13)
⁴ and X ⁵ are X ² , X ³ , X ⁴ in the general formula (12)
And X ⁵ and respectively show. Particularly preferred examples of the molybdenum dihydrocarbyl dithiocarbamate include, for example, molybdenum di (linear or branched) butyldithiocarbamate, di (linear or branched) pentyl dithiocarbamate molybdenum sulfide, di (linear or branched) Branches) molybdenum sulphide hexyldithiocarbamate, molybdenum sulphide di (linear or branched) heptyldithiocarbamate, molybdenum sulphide di (linear or branched) octyldithiocarbamate, molybdenum sulphide di (linear or branched) nonyldithiocarbamate sulphate, Molybdenum di (straight or branched) decyldithiocarbamate, molybdenum di (straight or branched) undecyldithiocarbamate, molybdenum di (straight or branched) dodecyldithiocarbamate, di (straight or branched) Toride Molybdenum didithiocarbamate, oxymolybdenum di (linear or branched) butyldithiocarbamate, oxymolybdenum di (linear or branched) pentyl dithiocarbamate, oxymolybdenum di (linear or branched) hexyldithiocarbamate oxymolybdenum sulfide, Oxymolybdenum sulfide di (linear or branched) heptyldithiocarbamate, oxymolybdenum sulfide di (linear or branched) octyldithiocarbamate, oxymolybdenum sulfide di (linear or branched) nonyldithiocarbamate, di (linear or branched) Branched) oxymolybdenum sulfide decyldithiocarbamate, oxymolybdenum sulfide di (linear or branched) undecyldithiocarbamate, oxymolybdenum sulfide di (linear or branched) dodecyldithiocarbamate, di (linear or branched) tri Sill oxymolybdenum sulfide, and the like, and mixtures thereof.

As the sulfide which is another example of the sulfur-based antioxidant, specifically, dihydrocarbyl sulfide represented by the following general formula (14) is preferred. Can be R ³⁰ -S _b -R ³¹ (14) (14) In the formula, R ³⁰ and R ³¹ each independently represent a linear or branched alkyl group having 1 to 22 carbon atoms, and 6 to 20 carbon atoms. An aryl group, an alkylaryl group having 7 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms, and b represents a number of 1 to 5, preferably 1 to 2, more preferably 2. Specific examples of R ³⁰ and R ³¹ include:
Each independently, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group,
ec-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 (tert-octyl group, etc. ), A straight-chain or branched nonyl group, a straight-chain or branched decyl group, a straight-chain or branched undecyl group, a straight-chain or branched dodecyl group (such as a tert-dodecyl group), a straight-chain or branched tridecyl group, A chain or branched tetradecyl group, a straight 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 nonadecyl group, linear or branched Branch icosyl group,
Alkyl groups such as straight-chain or branched henicosyl groups, straight-chain or branched docosyl groups; alkenyl groups such as propenyl group and butenyl group; aryl groups such as phenyl group and naphthyl group (including all isomers); tolyl group , Ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, xylyl, ethyl Methylphenyl, diethylphenyl, dipropylphenyl, dibutylphenyl, methylnaphthyl, ethylnaphthyl, propylnaphthyl, butylnaphthyl, dimethylnaphthyl, ethylmethylnaphthyl, diethylnaphthyl, dipropylnaphthyl , Djibouti Alkylaryl groups such as a naphthyl 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.); Benzyl group, phenethyl group,
An arylalkyl group such as a phenylpropyl group (the alkyl portion of these arylalkyl groups may be straight-chain or branched, and the substitution position of the aryl portion is arbitrary); Among the specific examples of R ³⁰ and R ³¹ , an alkyl group having 3 to 18 carbon atoms derived from propylene or isobutene;
An aryl group having 7 to 8 carbon atoms; an alkylaryl group having 7 to 8 carbon atoms; or an arylalkyl group having 7 to 8 carbon atoms. 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. Group, branched pentadecyl group derived from propylene pentamer, branched octadecyl group derived from propylene hexamer, ter
Alkyl groups such as t-butyl group, branched octyl group derived from isobutene dimer, branched dodecyl group derived from isobutene trimer, and branched hexadecyl group derived from isobutene tetramer. (These alkyl groups include all branched isomers.); Alkenyl groups such as propenyl group and butenyl group; alkylaryl groups such as phenyl group, tolyl group, ethylphenyl group and 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, carbon atoms derived from propylene or isobutene having 3 to 18 carbon atoms, particularly 6 to 1
5 alkyl groups are particularly preferred. Specific examples of dihydrocarbyl sulfide include dimethyl sulfides such as dimethyl monosulfide and dimethyl disulfide; diethyl sulfides such as diethyl monosulfide and diethyl disulfide; di-n-propyl monosulfide and di-n-propyl Di-n-propyl sulfides such as disulfide; diisopropyl sulfides such as diisopropyl monosulfide and diisopropyl disulfide; di-n-butyl sulfides such as di-n-butyl monosulfide and di-n-butyl disulfide; Diisobutyl sulfides such as diisobutyl monosulfide and diisobutyl disulfide; dise such as di-sec-butyl monosulfide and disec-butyl disulfide -
Butyl sulfides; di-tert-butyl sulfides such as di-tert-butyl monosulfide and di-tert-butyl disulfide; di (linear or branched pentyl) monosulfide, di (linear or branched pentyl) Di (linear or branched pentyl) sulfides such as disulfide; di (linear or branched hexyl) monosulfide, di (linear or branched hexyl)
Di (linear or branched hexyl) sulfides such as disulfide; dicyclohexyl monosulfide, dicyclohexyl sulfide such as dicyclohexyl disulfide; di (linear or branched heptyl) monosulfide, di (linear or branched heptyl) Di (linear or branched heptyl) sulfides such as disulfide; di-tert-octyl monosulfide, di-t
di-tert- such as ert-octyl disulfide
Octyl sulfides; di (linear or branched octyl) monosulfide, di (linear or branched octyl)
Di (linear or branched nonyl) sulfides such as disulfide; di (linear or branched nonyl) monosulfide, di (linear or branched nonyl) disulfide such as di (linear or branched nonyl) disulfide Di (linear or branched decyl) monosulfide, di (linear or branched decyl) disulfide, such as di (linear or branched decyl) disulfide; di (linear or branched undecyl) monosulfide Di (linear or branched undecyl) sulfides such as sulfide, di (linear or branched undecyl) disulfide; di-tert-dodecyl sulfide such as di-tert-dodecyl monosulfide, di-tert-dodecyl disulfide , Di (linear or branched dodecyl) monosulfide, di (linear or branched dodecyl) Di (linear or branched tridecyl) sulfides such as sulfide; di (linear or branched tridecyl) sulfide such as di (linear or branched tridecyl) monosulfide, di (linear or branched tridecyl) disulfide Di (linear or branched tetradecyl) monosulfides, di (linear or branched tetradecyl) disulfides, such as di (linear or branched tetradecyl) disulfide; di (linear or branched pentadecyl) monosulfide Di (linear or branched pentadecyl) sulfides such as di (linear or branched pentadecyl) disulfide; di-2 such as di-2-methylpentadecyl monosulfide and di-2-methylpentadecyl disulfide -Methylpentadecyl sulfide; di-tert-hexadecyl Di-tert-hexadecyl sulfides such as nosulphide, di-tert-hexadecyl disulfide; di (straight or branched hexadecyl) monosulfide, di (straight or branched hexadecyl) disulfide and the like. Di (linear or branched heptadecyl) sulfides; di (linear or branched heptadecyl) monosulfide, di (linear or branched heptadecyl) disulfide, etc .; di (linear) Or di (linear or branched octadecyl) disulfides such as di (linear or branched octadecyl) disulfide; di (linear or branched nonadecyl) monosulfide, di (linear or branched). Di (linear or branched) such as branched nonadecyl) disulfide Di (linear or branched icosyl) sulfides; di (linear or branched icosyl) disulfides such as di (linear or branched icosyl) disulfide; di (linear or branched icosyl) sulfides; Di (linear or branched henicosyl) sulfides such as branched henicosyl) monosulfide, di (linear or branched henicosyl) disulfide; di (linear or branched docosyl) monosulfide, di (linear or branched) Dokosil)
Di (linear or branched docosyl) sulfides such as disulfide; dipropenyl sulfides such as dipropenyl monosulfide and dipropenyl disulfide; dibutenyl sulfides such as dibutenyl monosulfide and dibutenyl disulfide; diphenyl mono Diphenyl sulfides such as sulfide and diphenyl disulfide; dinaphthyl monosulfide;
Dinaphthyl sulfides such as dinaphthyl disulfide; ditolyl sulfides such as ditolyl monosulfide and ditolyl disulfide; diethylphenyl sulfides such as diethylphenyl monosulfide and diethylphenyl disulfide; dipropylphenyl monosulfide and dipropylphenyl Dipropylphenyl sulfides such as disulfide; dibutylphenyl sulfides such as dibutyl phenyl monosulfide and dibutyl phenyl disulfide; dipentyl phenyl sulfides such as dipentyl phenyl monosulfide and dipentyl phenyl disulfide; dihexyl phenyl monosulfide and dihexyl phenyl disulfide Dihexylphenyl sulfides such as sulfide; Diheptylphenyl sulfides such as tylphenyl monosulfide and diheptylphenyl disulfide; dioctylphenyl sulfides such as dioctylphenyl monosulfide and dioctylphenyl disulfide; dinonylphenyl such as dinonylphenyl monosulfide and dinonylphenyl disulfide Sulfides; didecylphenyl sulfides such as didecylphenyl monosulfide and didecylphenyl disulfide; diundecylphenyl sulfides such as diundecylphenyl monosulfide and diundecylphenyl disulfide; didodecylphenyl monosulfide and didodecylphenyl Didodecylphenyl sulfides such as disulfide; dixylyl monosulfide; Dixylyl sulfides such as xylyl disulfide; diethyl methyl phenyl sulfides such as diethyl methyl phenyl monosulfide and diethyl methyl phenyl disulfide; di (diethyl phenyl) such as di (diethyl phenyl) mono sulfide and di (diethyl phenyl) disulfide ) Sulfides; di (dipropylphenyl) sulfides such as di (dipropylphenyl) monosulfide and di (dipropylphenyl) disulfide; di (dibutylphenyl) monosulfide, di (dibutylphenyl) disulfide and the like (Dibutylphenyl) sulfides; dimethyl naphthyl sulfides such as dimethyl naphthyl monosulfide and dimethyl naphthyl disulfide; diethyl naphthyl mono sulfide Diethyl naphthyl sulfides such as fido and diethyl naphthyl disulfide; dipropyl naphthyl sulfides such as dipropyl naphthyl monosulfide and dipropyl naphthyl disulfide; dibutyl naphthyl sulfides such as dibutyl naphthyl monosulfide and dibutyl naphthyl disulfide; dibenzyl Dibenzyl sulfides such as monosulfide and dibenzyl disulfide; diphenethyl sulfides such as diphenethyl monosulfide and diphenethyl disulfide; diphenyl propyl sulfides such as diphenyl propyl monosulfide and diphenyl propyl disulfide and mixtures thereof and the like Is mentioned.

Other compounds of the sulfides include diester sulfides represented by the following general formula (15). ^{_{R 32 OCO (CH 2) d}} S c (CH 2) e COOR 33 (15) (15) wherein, R ³² and R ^33, each independently, from 2 to 20 carbon atoms, preferably 4 to 20 linear It represents a chain or branched alkyl group, c represents a number of 1 to 2, preferably 1, and d and e each independently represent a number of 2 to 5, preferably 2. Specific examples of R ³² and R ³³ each independently include an ethyl group, an 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 group, linear or branched octyl group, linear or branched nonyl group, Chain or branched decyl, straight or branched undecyl, straight or branched dodecyl, straight or branched tridecyl, straight or branched tetradecyl, straight or branched pentadecyl, straight or branched Examples include a branched hexadecyl group, a straight or branched heptadecyl group, a straight or branched octadecyl group, a straight or branched nonadecyl group, a straight or branched icosyl group. Preferred specific examples of diester sulfides include a compound represented by the following chemical formula or a mixture thereof. C ₄ H ₉ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ COOC
_{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 (CH 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 (CH 2) 2 S (CH 2) 2 COOC
_{6 H 13, C 6 H 13} OCO (CH 2) 2 S 2 (CH 2) 2 COO
C ₆ H ₁₃ , C ₇ H ₁₅ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ COO
C ₇ H ₁₅ , C ₇ H ₁₅ OCO (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ CO
OC ₇ H ₁₅ , C ₈ H ₁₇ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ CO
OC ₈ H ₁₇ , C ₈ H ₁₇ OCO (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ C
OOC ₈ H ₁₇ , C ₉ H ₁₉ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ C
OOC 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 (C
H ₂ ) ₂ COOC 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 (C
H ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC ₁₂ H ₂₅ , C ₁₃ H ₂₇ OCO
(CH ₂ ) ₂ S (CH ₂ ) ₂ COOC ₁₃ H ₂₇ , C ₁₃ H ₂₇ OC
O (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC ₁₃ H ₂₇ , C ₁₄ H ₂₉
OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ COOC 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 OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ COOC _{16
H 33, C 16 H 33 OCO} (CH 2) 2 S 2 (CH 2) 2 COO
C ₁₆ H ₃₃ , C ₁₇ H ₃₅ OCO (CH ₂ ) ₂ S (CH ₂ ) ₂ CO
OC 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 (C
H 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 OCO (CH 2) 2
_{S (CH 2) 2 COOC 19} H 39, C 19 H 39 OCO (C
H ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC ₁₉ H ₃₉ , C ₂₀ H ₄₁ OCO
(CH ₂ ) ₂ S (CH ₂ ) ₂ COOC ₂₀ H ₄₁ , C ₂₀ H ₄₁ OC
O (CH ₂ ) ₂ S ₂ (CH ₂ ) ₂ COOC ₂₀ H ₄₁ ,

As other compounds of the sulfides, there may be mentioned tetraester tetrasulfide represented by the following general formula (16). ^{_{(R 34 SCH 2 CH 2 COOCH}} 2) 4 C (16) (16) wherein, R ³⁴ is from 8 to 20 carbon atoms, preferably 10
-18 represents a linear or branched alkyl group. R ³⁴
Specific examples of a linear or branched octyl group, a linear or branched nonyl group, a linear or branched decyl group, a linear or branched undecyl group, a linear or branched dodecyl group, a linear or 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 nonadecyl And a straight-chain or branched icosyl group, particularly preferably a straight-chain or branched dodecyl group, and a straight-chain or branched tridecyl group. Specific examples of the tetraester tetrasulfide include a compound represented by the following chemical formula or a mixture thereof, and (C ₈ H ₁₇ SCH ₂ CH ₂ CO
OCH 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 SCH
₂ CH ₂ COOCH ₂ ) ₄ C, (C ₁₃ H ₂₇ SCH ₂ CH ₂ CO
OCH ₂ ) ₄ C, (C ₁₄ H ₂₉ SCH ₂ CH ₂ COOCH ₂ ) ₄
C, (C ₁₅ H ₃₁ SCH ₂ CH ₂ COOCH 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 CO
OCH 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 Among them, (C ₁₂ H ₂₅ SCH ₂ CH ₂ COOCH ₂ ) ₄ C is particularly preferable.

As a matter of course, as the component (B) of the present invention, one kind selected from the above-mentioned hindered phenol-based, aromatic amine-based and sulfur-based antioxidants is used. The compound may be used alone, and further, selected from hindered phenol-based, aromatic amine-based, and sulfur-based antioxidants as described above.
A mixture of two or more kinds of compounds at an arbitrary mixing ratio may be used. However, in the present invention, the component (B) is a hindered phenol type; an aromatic amine type; It is preferable to use one kind of compound selected from metal-containing sulfur-based antioxidants such as hydrocarbyl dithiophosphates and metal dithiocarbamates, or a mixture of two or more kinds of compounds at an arbitrary mixing ratio. In the case of using a sulfur-based antiparticipant containing no metal, a hindered phenol-based antioxidant; an aromatic amine-based antioxidant; It is preferable to use together with one kind of compound selected from or two or more kinds of compounds.

The content of the component (B) in the lubricating oil composition of the present invention is optional, but usually the lower limit of the content is 0.1% by mass, preferably 0% by mass, based on the total amount of the lubricating oil composition. 0.2% by mass, while the upper limit of the content is 5.
0% by mass, preferably 2.0% by mass. When the content of the component (B) is less than 0.1% by mass based on the total amount of the lubricating oil composition, the effect of improving the oxidation stability by the content of the component (B) is not sufficient. If it exceeds 5.0% by mass based on the total amount of the substance, the effect of improving the oxidation stability corresponding to the content cannot be obtained, which is economically disadvantageous.

The lubricating oil composition of the present invention has excellent oxidation stability by itself, but in order to further enhance these various performances, known lubricating oil additives are 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,
Detergents such as alkaline earth metal salicylates and alkaline earth metal phenates; ashless dispersants such as polybutenyl succinimides, long-chain alkyl polyamines, amides of long-chain fatty acids and polyamines or borides thereof; organic phosphate esters , Organic phosphites, fatty acids, fatty acid esters, fatty alcohols and other antiwear agents; molybdenum dithiophosphate, molybdenum disulfide, long chain aliphatic amines, long chain fatty acids, long chain fatty acid esters, long chain fatty alcohols, etc. Rust inhibitors such as petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinate, polyhydric alcohol ester; polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene Polyalkylene glycol demulsifier typified by non-ionic surfactants such as alkylene alkyl naphthyl ether; imidazoline, pyrimidine derivatives, alkyl thiadiazole, mercapto benzothiazole, benzotriazole or derivatives thereof, 1,3,
4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bisdialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, β-
Metal deactivator such as (o-carboxybenzylthio) propionnitrile; antifoaming agent such as silicone, fluorosilicone, fluoroalkyl ether; viscosity index improver such as polymethacrylate, olefin copolymer or hydride thereof; polymethacrylate and the like Pour point depressants and the like. When these additives are added to the lubricating oil composition of the present invention, the amount of addition is also arbitrary, but usually, from 0.0005 to 1 wt. Parts by weight, 0.005 to 1 parts by weight for the metal deactivator, and 0.1 to 15 parts by weight for the other additives.

The lubricating oil composition of the present invention is 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 and marine diesel engines; automatic transmission oils, manual transmission oils, differential oils and the like. Automotive gear oils; industrial gear oils; turbine oils; hydraulic oils; compressor oils; refrigeration oils; cutting oils; rolling oils, press oils, forging oils, drawing oils, drawing oils, punching oils, and other plastic working oils Metal lubricating oils such as heat treatment oils and electric discharge machining oils; sliding guide surface oils; bearing oils; rust preventive oils;

[0023]

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.

Examples 1 to 7 and Comparative Examples 1 to 5 Various lubricating oil compositions having compositions as shown in the respective examples of Table 1 were produced, and these compositions were subjected to JIS K2514.
The oxidation life was measured by a rotating cylinder type oxidation stability test specified in the above. The results are shown in the lower column of Table 1. The lubricating base oil and antioxidant used are shown below.

Component (A): Mineral oil-based lubricating base oil Refined mineral oil A Saturated hydrocarbon component 96.1 mass% Viscosity of saturated hydrocarbon component-density constant 0.781 Kinematic viscosity 100 ° C. 4.155 mm ² / s 40 C. 18.73 mm ² / s Viscosity index 126 Pour point -22.5 ° C. Refined mineral oil B Saturated hydrocarbon component 93.9% by mass Viscosity of saturated hydrocarbon component-density constant 0.772 Kinematic viscosity 100 ° C. 4.337 mm ² / s 40 ° C. 19.88 mm ² / s Viscosity index 128 Pour point -22.5 ° C. Refined mineral oil C Saturated hydrocarbon component 73.2 mass% Viscosity of saturated hydrocarbon component-density constant 0.781 Kinematic viscosity 100 ° C. 4 .394 mm ² / s 40 ° C. 21.65 mm ² / s Viscosity index 112 Pour point −15 ° C. Refined mineral oil D Saturated hydrocarbon component 98.9 mass% Viscosity of saturated hydrocarbon component-density constant 0.806 Kinematic viscosity 100 ° C. 4.176mm ² / s 40 ° C. 20.59 mm ² / s Viscosity index 105 Pour point -12.5 ° C. Component (B): antioxidant hindered phenol A 2,6-di-tert-butyl-p-cresol hinder Dophenol B 2,6-di-tert-butyl-4-ethyl phenol aromatic amine A phenyl-α-naphthylamine aromatic amine B p, p′-dibranched nonyldiphenylamine sulfur A zinc zinc dialkyldithiophosphate (Alkyl group is a mixed alkyl group of sec-butyl group and sec-hexyl group) Sulfur B dibenzyl disulfide Sulfur C dilaurylthiodipropionate

[0026]

[Table 1]

As is clear from the results in Table 1, the lubricating oil compositions according to the present invention (Examples 1 to 7) all show excellent oxidation stability. On the other hand, in Comparative Example 1 using only the base oil of the present invention and no antioxidant was added, only the refined mineral oil C having a saturated hydrocarbon component of less than 80% by mass was used instead of the base oil of the present invention. Comparative Example 2 and Comparative Example 4 using only refined mineral oil D having a viscosity-density constant of the saturated hydrocarbon component of more than 0.79 both have very poor oxidation stability. Further, as can be seen from Comparative Examples 3 and 5, the viscosity of refined mineral oil C or a saturated hydrocarbon component in which the saturated hydrocarbon component is less than 80% by mass instead of the base oil of the present invention.
Even if an antioxidant is added to refined mineral oil D having a density constant of more than 0.79, its oxidation stability is not significantly improved. In short, the oxidation stability is improved by specifying the content of the saturated hydrocarbon component of the base oil and the viscosity-density constant of the saturated hydrocarbon component. That is, from the comparison between Example 1, Comparative Examples 3 and 5, and Comparative Examples 1, 2, and 4, it was found that the oxidation stability was significantly improved only when an antioxidant was added to the base oil of the present invention. In other cases, the oxidation stability is not improved. Therefore, when an antioxidant is added to the base oil of the present invention, it is apparent that a synergistic effect of the base oil and the antioxidant with respect to the improvement of oxidation stability is obtained.

[0028]

In summary, according to the present invention, the content of the saturated hydrocarbon component of the base oil and the viscosity-density constant of the saturated hydrocarbon component are specified to provide a lubricating oil composition having excellent oxidation stability. Things are obtained.

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Claims (1)

[Claims] 1. A lubricating oil composition obtained by adding an antioxidant to a lubricating base oil, wherein the lubricating base oil contains at least 80% by mass of a saturated hydrocarbon component, and A lubricating oil composition characterized by having a viscosity-density constant of 0.79 or less.