WO2016159041A1 - Lubricant composition and method for producing lubricant composition - Google Patents

Abstract

Provided is a lubricant composition which contains (A) a sulfur-based antioxidant and (B) an amine-based antioxidant together with a base oil, and which satisfies the conditions (I) and (II) described below. Condition (I): The total content of sulfur atoms and nitrogen atoms is 0.010-0.600% by mass based on the total mass of the lubricant composition. Condition (II): The content ratio of sulfur atoms to nitrogen atoms, namely (sulfur atoms)/(nitrogen atoms) is 0.45-20.00 in terms of mass ratio. This lubricant composition has excellent stability with respect to oxidation, which enables suppression of negative effects of oxidation degradation due to a long period of use such as increase in the acid value and the kinematic viscosity, increase of sludge, and adhesion of the sludge to a devices, a filter or the like.

Description

Lubricating oil composition and method for producing lubricating oil composition

The present invention relates to a lubricating oil composition and a method for producing a lubricating oil composition.

The compressor increased the pressure by applying work to the air and various gases (nitrogen gas, oxygen gas, hydrogen gas, ammonia gas, carbon dioxide gas, carbon monoxide gas, various hydrocarbon gases, etc.) from outside. It is a device that sends out compressed gas.
Such compressors are divided into positive displacement compressors and turbo compressors based on the operating principle of increasing the pressure of air and various gases, and positive displacement compressors are classified into reciprocating compressors and rotary compressors. Further classified.

A rotary compressor is superior to reciprocating compressors in terms of resource saving, low noise, low vibration, and high efficiency, and is widely used.
Lubricating oil compositions used in rotary compressors have a large contact area with high-temperature and high-pressure air and various gases, and are used for a long time in a high-temperature environment. Since property deterioration due to oxidation is likely to be caused, high oxidation stability is required.

In addition, the rotary compressor is increasingly operated in a bad environment such as in an atmosphere of an oxidizing gas such as SO _X or NO _X. The lubricating oil composition used in such a bad environment is likely to generate sludge, and the sludge adheres to the inside of the device or causes clogging of the filter, thereby making the device inoperable. .
In particular, recently developed rotary compressors tend to be further miniaturized. The downsized rotary compressor has a problem that the apparatus cannot be operated due to the generation of sludge in a short period of time.

In order to solve such problems, lubricating oil compositions used for various rotary compressors have been proposed.
For example, Patent Document 1 discloses a lubricating oil composition comprising a base oil containing a compound containing an amine-based antioxidant with a total nitrogen amount of 800 ppm or more and a phosphorus atom and / or a sulfur atom. ing.
The lubricating oil composition described in Patent Document 1 has an amine-based antioxidant as a main component as an antioxidant, and the lubricating oil composition is prepared by adjusting the content of the amine-based antioxidant to a predetermined value or more. The oxidative stability of the product is improved.

Patent Document 2 discloses a lubricating oil composition for an air compressor containing a synthetic base oil and an amine-based antioxidant having a specific asymmetric structure such as an asymmetric diphenylamine-based compound.
The lubricating oil composition described in Patent Literature 2 uses an amine-based antioxidant having a specific asymmetric structure as an antioxidant to improve the oxidation stability of the lubricating oil composition.

International Publication No. 2007/066713 International Publication No. 2013/146805

However, although the lubricating oil compositions described in Patent Documents 1 and 2 can be expected to have a certain degree of oxidation stability, further improvement in oxidation stability is required.
The present invention has excellent oxidative stability that can suppress adverse effects due to oxidative degradation such as an increase in acid value and kinematic viscosity, an increase in sludge amount, and adhesion of the sludge to devices, filters, etc., due to long-term use. It is an object of the present invention to provide a lubricating oil composition and a method for producing the lubricating oil composition.

The inventor predetermines a total content of sulfur atoms and nitrogen atoms and a content ratio of sulfur atoms and nitrogen atoms in a lubricating oil composition containing a sulfur-based antioxidant and an amine-based antioxidant. The present invention was completed by finding out that the above-mentioned problems can be solved by preparing in the range of.

That is, the present invention provides the following [1] to [4].
[1] A lubricating oil composition comprising a base oil, a sulfur-based antioxidant (A), and an amine-based antioxidant (B) and satisfying the following requirements (I) and (II).
Requirement (I): The total content of sulfur atoms and nitrogen atoms is 0.010 to 0.600 mass% based on the total mass of the lubricating oil composition.
Requirement (II): The content ratio of sulfur atom to nitrogen atom [sulfur atom / nitrogen atom] is 0.45 to 20.00 by mass ratio.
[2] A method for using a lubricating oil composition, wherein the lubricating oil composition according to [1] is used in a rotary compressor.
[3] A rotary compressor using the lubricating oil composition according to [1].
[4] Manufacture of a lubricating oil composition comprising a step of blending a sulfur-based antioxidant (A) and an amine-based antioxidant (B) with a base oil so as to satisfy the following requirements (I) and (II) Method.
Requirement (I): The total content of sulfur atoms and nitrogen atoms is 0.010 to 0.600 mass% based on the total mass of the lubricating oil composition.
Requirement (II): The content ratio of sulfur atom to nitrogen atom [sulfur atom / nitrogen atom] is 0.45 to 20.00 by mass ratio.

Since the lubricating oil composition of the present invention has excellent oxidative stability, the deterioration due to oxidation such as an increase in acid value and kinematic viscosity, an increase in sludge amount, and adhesion of the sludge to equipment and filters due to long-term use. It is possible to effectively suppress the adverse effects caused by.

In this specification, for example, the notation “content ratio of component (X) to component (Y) [(X) / (Y)]” is “component (X) relative to the content of component (Y)”. ) Content ratio ”.

[Lubricating oil composition]
The lubricating oil composition of the present invention comprises a base oil, a sulfur-based antioxidant (A) (hereinafter also referred to as “component (A)”), and an amine-based antioxidant (B) (hereinafter referred to as “component (B)”. And also satisfy the following requirements (I) and (II).
Requirement (I): The total content of sulfur atoms and nitrogen atoms is 0.010 to 0.600 mass% based on the total mass (100 mass%) of the lubricating oil composition.
Requirement (II): The content ratio of sulfur atom to nitrogen atom [sulfur atom / nitrogen atom] is 0.45 to 20.00 by mass ratio.
In the present specification, the sulfur atom content is a value measured according to JIS K2541-6: 2013, and the nitrogen atom content is a value measured according to JIS K2609: 1998. It is.

Many sulfur-based compounds such as sulfur-based antioxidants also have extreme pressure properties, and are excellent in suppressing the increase in acid value and kinematic viscosity of the lubricating oil composition.
However, the sulfur atom of the sulfur-based compound tends to cause sludge generation. That is, the sulfur-based compound is likely to be altered or decomposed and become sludge after long-term use. And the said sludge adheres to an apparatus or a filter, and causes a malfunction of an apparatus.
In addition, the antioxidant function is lost due to the alteration or decomposition of the sulfur-based antioxidant, which causes an adverse effect such as an increase in the acid value and kinematic viscosity of the lubricating oil composition.
The inventor of the present invention uses a specific amount of an amine-based antioxidant together with a sulfur-based antioxidant, thereby suppressing the oxidative deterioration of the base oil and providing a lubricating oil composition with a markedly improved oxidation stability. I found that I can do it.
This is thought to be due to the addition of an amine antioxidant to compensate for a decrease in antioxidant performance due to alteration or decomposition of the sulfur-based antioxidant. As a result, a high antioxidant performance can be maintained, and as a result, the oxidative deterioration of the base oil can be remarkably suppressed, and a lubricating oil composition with significantly improved oxidation stability can be obtained.

In the lubricating oil composition of one embodiment of the present invention, additives for lubricating oil other than components (A) and (B) can also be included.
As such an additive for lubricating oil, “a compound containing a sulfur atom (for example, a metal sulfonate detergent or the like)” which does not have an antioxidant performance and does not correspond to the components (A) and (B). Or “a compound containing a nitrogen atom (for example, an imide-based detergent dispersant)” may be used.
However, many of these “compounds containing sulfur atoms” and “compounds containing nitrogen atoms” have a small blending amount or low solubility in base oil, and the above requirements (I) and (II ) Value is relatively small.

When the total content of sulfur atoms and nitrogen atoms specified in the above requirement (I) is less than 0.010% by mass, the antioxidant performance is hardly exhibited, and the oxidation stability of the lubricating oil composition is inferior.
On the other hand, when the total content exceeds 0.600% by mass, a large amount of sludge is likely to be generated in a long-time use, and the sludge is likely to adhere to the apparatus and the filter. Also, adverse effects such as an increase in the acid value and kinematic viscosity of the lubricating oil composition due to the generation of sludge can occur.

From the above viewpoint, the total content of sulfur atoms and nitrogen atoms specified in the above requirement (I) is preferably 0.030 to 0.500 mass based on the total mass (100 mass%) of the lubricating oil composition. %, More preferably 0.050 to 0.450 mass%, still more preferably 0.070 to 0.400 mass%, and still more preferably 0.085 to 0.360 mass%.

In the lubricating oil composition of one embodiment of the present invention, the total content of sulfur atoms derived from the antioxidant and nitrogen atoms derived from the antioxidant is the total mass of the lubricating oil composition (100 % By weight), preferably 0.008 to 0.580% by weight, preferably 0.020 to 0.480% by weight, more preferably 0.040 to 0.440% by weight, still more preferably 0.060 to The amount is 0.400% by mass, more preferably 0.080 to 0.380% by mass.

When the content ratio [sulfur atom / nitrogen atom] of sulfur atom and nitrogen atom defined in the above requirement (II) is less than 0.45, the content of sulfur-based antioxidant (A) is relatively small. Therefore, it is difficult to suppress an increase in the acid value and kinematic viscosity of the lubricating oil composition.
On the other hand, if the content ratio exceeds 20.00, the content of the sulfur-based antioxidant (A) is relatively high, and the amine-based system is associated with a decrease in the antioxidant performance of the sulfur-based antioxidant (A). The supplement of the antioxidant (B) is insufficient, and it is difficult to maintain the antioxidant performance. As a result, the use of the lubricating oil composition for a long period of time causes a large amount of sludge to be generated and the sludge adheres to the device or filter, and causes the base oil to be oxidized and deteriorated due to the generated sludge. It tends to cause changes in the acid number and kinematic viscosity of the composition.

From the above viewpoint, the content ratio [sulfur atom / nitrogen atom] of the sulfur atom and the nitrogen atom defined in the above requirement (II) is preferably 0.45 to 15.00, more preferably 0 by mass ratio. .45 to 12.00, more preferably 0.46 to 10.00, and still more preferably 0.47 to 7.00.

In the lubricating oil composition of one embodiment of the present invention, the content ratio [sulfur atom / nitrogen atom] of the sulfur atom derived from the antioxidant and the nitrogen atom derived from the antioxidant is preferably 0. .47 to 25.00, more preferably 0.47 to 20.00, more preferably 0.47 to 15.00, still more preferably 0.47 to 12.00, still more preferably 0.47 to 10. 00.

Further, from the viewpoint of further improving the oxidation stability of the lubricating oil composition, the phosphorus atom content in the lubricating oil composition of one aspect of the present invention is based on the total mass (100 mass%) of the lubricating oil composition. Preferably, the content is 0.001 to 0.200% by mass, more preferably 0.003 to 0.150% by mass, and still more preferably 0.004 to 0.120% by mass.

From the same viewpoint as described above, in the lubricating oil composition of one embodiment of the present invention, the content ratio of phosphorus atom to sulfur atom [phosphorus atom / sulfur atom] is preferably 0.01 to 2 in terms of mass ratio. 0.00, more preferably 0.02 to 1.50, still more preferably 0.05 to 1.20.
In the present specification, the phosphorus atom content means a value measured according to JPI-5S-38-92.

Moreover, content of a phosphorus atom can be adjusted by containing a phosphorus compound.
As the phosphorus compound, an antioxidant containing a phosphorus atom is preferable.
As the antioxidant containing a phosphorus atom, a compound (A2) containing a phosphorus atom and a sulfur atom corresponding to the component (A) described later, and a phenolic antioxidant containing a phosphorus atom are preferable.

In the lubricating oil composition of one embodiment of the present invention, the content of phosphorus atoms derived from the antioxidant is preferably 0.001 to 0.190 mass based on the total mass (100 mass%) of the lubricating oil composition. %, More preferably 0.002 to 0.140 mass%, still more preferably 0.003 to 0.110 mass%.

In the lubricating oil composition of one embodiment of the present invention, the content ratio [phosphorus atom / sulfur atom] of the phosphorus atom derived from the antioxidant and the sulfur atom derived from the antioxidant is preferably a mass ratio, Is from 0.01 to 2.00, more preferably from 0.02 to 1.50, still more preferably from 0.03 to 1.20.

That is, in the lubricating oil composition of one embodiment of the present invention, the content of the component (A) is appropriately adjusted so as to satisfy the requirements (I) and (II), but the total mass of the lubricating oil composition On the basis of (100% by mass), preferably 0.007 to 6.00% by mass, more preferably 0.020 to 5.00% by mass, still more preferably 0.10 to 4.00% by mass, and still more preferably 0.30 to 3.00% by mass.

In the lubricating oil composition of one embodiment of the present invention, the content of the component (B) is appropriately adjusted so as to satisfy the requirements (I) and (II), but the total mass (100 of the lubricating oil composition) % By weight), preferably 0.003 to 4.00% by weight, more preferably 0.010 to 3.00% by weight, still more preferably 0.050 to 2.50% by weight, and still more preferably 0.00. It is 10 to 2.00% by mass.

In the lubricating oil composition of one embodiment of the present invention, the total content of the component (A) and the component (B) is appropriately adjusted so as to satisfy the above requirement (I). On a mass (100% by mass) basis, preferably 0.01 to 10.00% by mass, more preferably 0.03 to 8.00% by mass, still more preferably 0.15 to 5.00% by mass, and still more preferably. Is 0.40 to 3.50 mass%.

In the lubricating oil composition of one embodiment of the present invention, the content ratio [(A) / (B)] of the component (A) and the component (B) is appropriately adjusted so as to satisfy the requirement (II). However, the mass ratio is preferably 0.40 to 20.00, more preferably 0.45 to 10.00, still more preferably 0.50 to 6.00, and still more preferably 0.55 to 4.50. It is.

The lubricating oil composition of one embodiment of the present invention may further contain an antioxidant other than components (A) and (B).
In particular, from the viewpoint of further improving the oxidative stability of the lubricating oil composition, the lubricating oil composition of one embodiment of the present invention includes, in addition to the components (A) and (B), a phenolic antioxidant (C). It is preferable to include.

In the lubricating oil composition of one embodiment of the present invention, the content of the component (C) is preferably 0.001 to 4.00 mass%, based on the total mass (100 mass%) of the lubricating oil composition. The amount is preferably 0.005 to 3.00% by mass, more preferably 0.010 to 2.50% by mass, and still more preferably 0.030 to 2.00% by mass.

In the lubricating oil composition of one embodiment of the present invention, the total content of the antioxidant is preferably 0.01 to 10.00% by mass based on the total mass (100% by mass) of the lubricating oil composition. The amount is preferably 0.05 to 8.00% by mass, more preferably 0.15 to 6.00% by mass, and still more preferably 0.50 to 4.00% by mass.

In the lubricating oil composition of one embodiment of the present invention, the total content of the base oil, component (A), and component (B) is preferably 55 based on the total mass (100% by mass) of the lubricating oil composition. 0.01 to 100% by mass, more preferably 60 to 99.999% by mass, still more preferably 70 to 99.99% by mass, still more preferably 80 to 99.9% by mass, particularly preferably 90 to 99% by mass. is there.

In the lubricating oil composition of one embodiment of the present invention, the total content of the base oil, component (A), component (B), and component (C) is based on the total mass (100% by mass) of the lubricating oil composition. Preferably, it is 55.01 to 100% by mass, more preferably 60 to 100% by mass, still more preferably 70 to 100% by mass, still more preferably 80 to 100% by mass, and particularly preferably 90 to 100% by mass. .

<Sulfur-based antioxidant (A)>
As the sulfur-based antioxidant (A), any compound containing at least one sulfur atom and having an effect of suppressing oxidation of the lubricating oil composition can be used.
In addition, if the sulfur type compound generally used as an extreme pressure agent also has a function as an antioxidant, it shall belong to a component (A).

As the sulfur-based antioxidant (A), from the viewpoint of obtaining a lubricating oil composition with further improved oxidation stability, the compound (A1) containing no sulfur atom and containing a sulfur atom, and phosphorus atom and sulfur. It is preferable to include one or more selected from the compound (A2) containing an atom, and it is more preferable to include both the compound (A1) and the compound (A2).

In one embodiment of the present invention, the content ratio [(A1) / (A2)] of the compound (A1) and the compound (A2) is preferably 0 to 2.00, more preferably 0 to 1.50, more preferably 0 to 1.00, still more preferably 0.01 to 0.80.

Examples of the compound (A1) include dialkyl sulfides such as didodecyl sulfide and dioctadecyl sulfide; didodecyl thiodipropionate, dioctadecyl thiodipropionate, dilauryl thiodipropionate, distearyl thiodipropionate, And thiodipropionic acid esters such as dimyristylthiodipropionate, dodecyloctadecylthiodipropionate, pentaerythritol-tetrakis- (3-laurylthiopropionate); and the like.
Examples of the compound (A1) include phenothiazine, 2,6-di-t-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol, And compounds containing sulfur and nitrogen atoms such as mercaptobenzimidazole.
Further, examples of the compound (A1) include bis (3,5-di-t-butyl-4-hydroxybenzyl) sulfide, 2,2′-thiobis (4-methyl-6-t-butylphenol), 4, A phenolic compound containing a sulfur atom such as 4′-thiobis (3-methyl-6-t-butylphenol) is also included.

Examples of the compound (A2) include zinc dialkyldithiophosphates such as zinc di-2-ethylhexyldithiophosphate; thioterpene compounds such as triphenyl phosphorothioate, tricresyl phosphorothioate, a reaction product of phosphorus pentasulfide and pinene; 2 , 2'-thiobis (4-methyl-6-t-butylphenol) and the like.
The compound (A2) also includes a compound containing a phosphorus atom, a sulfur atom and a nitrogen atom, and specific examples thereof include triphenylamine phosphorothioate.
Among these compounds (A2), a compound represented by the following general formula (a2-1) is preferable.

In the general formula (a2-1), X ¹ to X ³ are each independently an oxygen atom or a sulfur atom, preferably an oxygen atom.
R ¹ to R ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, and is preferably a phenyl group.
The phenyl group may be further substituted with a substituent selected from an alkyl group having 1 to 4 carbon atoms, an amino group, a hydroxyl group, and a halogen atom.
Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a t-butyl group.

<Amine-based antioxidant (B)>
In the present invention, the amine-based antioxidant (B) is a compound that does not contain a sulfur atom and in which at least one hydrogen atom of ammonia (NH ₃ ) is substituted with a hydrocarbon group, and the lubricating oil composition Any compound can be used as long as it has an effect of suppressing oxidation of the compound.
As described above, an amine-based antioxidant containing a sulfur atom (for example, 2,6-di-t-butyl-4- (4,6-bis (octylthio) -1,3,5-triazine-2) -Ylamino) phenol and the like) are excluded from component (B) as defined in the present invention.
In the present invention, such an amine-based antioxidant containing a sulfur atom belongs to the component (A).

Among such amine antioxidants (B), an aromatic amine compound is preferable, and at least one selected from a diphenylamine compound and a naphthylamine compound is more preferable.

Examples of the diphenylamine compound include monoalkyl diphenylamine compounds such as monooctyl diphenylamine and monononyl diphenylamine; 4,4′-dibutyldiphenylamine, 4,4′-dipentyldiphenylamine, 4,4′-dihexyldiphenylamine, 4,4 Dialkyldiphenylamine compounds such as' -diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-dinonyldiphenylamine; polyalkyldiphenylamine compounds such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine 4,4′-bis (α, α-dimethylbenzyl) diphenylamine and the like.

Examples of the naphthylamine compound include 1-naphthylamine, phenyl-1-naphthylamine, butylphenyl-1-naphthylamine, pentylphenyl-1-naphthylamine, hexylphenyl-1-naphthylamine, heptylphenyl-1-naphthylamine, octylphenyl-1 -Naphthylamine, nonylphenyl-1-naphthylamine, decylphenyl-1-naphthylamine, dodecylphenyl-1-naphthylamine and the like.

<Phenolic antioxidant (C)>
In the present invention, the phenolic antioxidant (C) is a compound that does not contain a sulfur atom and an amino group, has a phenol structure, and has an effect of suppressing oxidation of the lubricating oil composition. Can be used.
In addition, the phenolic antioxidant containing a sulfur atom and the phenolic antioxidant which has an amino group are excluded from the component (C) defined by this invention.
In the present invention, such a phenolic antioxidant containing a sulfur atom belongs to the component (A), and a phenolic antioxidant having an amino group belongs to the component (B).
The phenolic antioxidant (C) may be a monocyclic phenolic antioxidant or a polycyclic phenolic antioxidant.

Monocyclic phenolic antioxidants include, for example, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4,6-tri- t-butylphenol, 2,6-di-t-butyl-4-hydroxymethylphenol, 2,6-di-t-butylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t- Butyl-4- (N, N-dimethylaminomethyl) phenol, 2,6-di-t-amyl-4-methylphenol, n-octadecyl-3- (3,5-di-t-butyl-4-hydroxy Phenyl) propionate and the like.

Examples of the polycyclic phenol-based antioxidant include 4,4′-methylenebis (2,6-di-t-butylphenol), 4,4′-isopropylidenebis (2,6-di-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-bis (2,6-di-t-butylphenol), 4,4'-bis (2-methyl-6-t -Butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), and the like.

In addition, it is preferable that a component (C) contains the phenol type compound (C1) containing a phosphorus atom from a viewpoint of setting it as the lubricating oil composition which improved oxidation stability more.
Examples of the compound (C1) include diethyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate.

The content of the phenol compound (C1) containing a phosphorus atom is preferably 1 to 100% by mass, more preferably 3 to 60% by mass, based on the total mass (100% by mass) of the component (C). The amount is preferably 5 to 40% by mass, and more preferably 7 to 20% by mass.

Further, from the viewpoint of providing a lubricating oil composition with further improved oxidation stability, the molecular weight of component (C) is preferably 250 or more, more preferably 300 or more, still more preferably 320 or more, and usually 2000 or less. It is.

<Base oil>
The base oil used in the present invention may be mineral oil, synthetic oil, or a mixed oil of mineral oil and synthetic oil.
Mineral oil includes, for example, atmospheric residual oil obtained by atmospheric distillation of crude oil such as paraffinic mineral oil, intermediate mineral oil, and naphthenic mineral oil; distillate obtained by vacuum distillation of these atmospheric residual oils Refined oils and waxes that have been subjected to one or more purification treatments such as solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrogenation reforming, etc .; by Fischer-Tropsch method, etc. And mineral oil obtained by isomerizing the produced wax (GTL wax).
Among these, paraffinic mineral oils and intermediate group systems obtained by performing one or more refining treatments selected from solvent deburring, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrogenation reforming Mineral oil and naphthenic mineral oil are preferred.

Synthetic oils include, for example, α-olefin homopolymers or α-olefin copolymers (eg, α-olefin copolymers having 8 to 14 carbon atoms such as ethylene-α-olefin copolymers). α-olefin; various olefins such as polybutene; isoparaffin; polyol ester, dibasic acid ester (for example, ditridecyl glutarate), tribasic acid ester (for example, 2-ethylhexyl trimellitic acid), phosphoric acid ester, etc. Examples include esters; various ethers such as polyphenyl ether; polyalkylene glycols; alkyl benzenes; alkyl naphthalenes; synthetic oils obtained by isomerizing a wax (GTL wax) produced by the Fischer-Tropsch method, and the like.
Among these, poly α-olefin, various esters, and polyalkylene glycol are preferable.

In one embodiment of the present invention, the base oil selected from these mineral oils and synthetic oils may be used alone or in combination of two or more.

The kinematic viscosity at 40 ° C. of the base oil used in the present invention, lubricating, cooling performance, and in terms of reduction of friction loss during stirring, preferably 10 ~ 200mm ² / s, more preferably 15 ~ 150 mm ² / s, more preferably 20 to 100 mm ² / s.

The kinematic viscosity at 100 ° C. of the base oil used in the present invention is preferably 1.0 to 50 mm ² / s, more preferably 1.5 to 30 mm ² / s, still more preferably 2.0 to 20 mm ² / s. is there.

The viscosity index of the base oil used in the present invention is preferably 60 or more, more preferably 75 or more, and still more preferably from the viewpoint of suppressing the viscosity change due to temperature change and improving fuel economy. Is 90 or more.

The density at 15 ℃ of the base oil used in the present invention, preferably 0.700 g / cm ³ or more, more preferably 0.750 g / cm ³ or more, more preferably 0.800 g / cm ³ or more, Preferably it is 1.250 g / cm ³ or less.

When a mixed base oil composed of two or more base oils is used as the base oil, the kinematic viscosity at 40 ° C., the kinematic viscosity at 100 ° C., the viscosity index, and the density at 15 ° C. of the mixed base oil are in the above range. It only has to be inside.
In addition, for each base oil of “two or more types of base oils”, if the kinematic viscosity at 40 ° C., the kinematic viscosity at 100 ° C., the viscosity index, and the density at 15 ° C. are within the above ranges, “the mixed base Also for oil, it can be considered that the kinematic viscosity at 40 ° C., the kinematic viscosity at 100 ° C., the viscosity index, and the density at 15 ° C. are within the above ranges.
In the present specification, the kinematic viscosity at 40 ° C., the kinematic viscosity at 100 ° C., and the viscosity index mean values measured in accordance with JIS K2283: 2000.
Furthermore, in this specification, the density at 15 ° C. means a value measured according to JIS K2249: 2011.

In the lubricating oil composition of one embodiment of the present invention, the content of the base oil is preferably 55% by mass or more, more preferably 60% by mass or more, based on the total mass (100% by mass) of the lubricating oil composition. More preferably, it is 65 mass% or more, More preferably, it is 70 mass% or more, Preferably it is 99.9 mass% or less, More preferably, it is 99.0 mass% or less.

<Other lubricant additives>
The lubricating oil composition of the present invention may contain additives for lubricating oil other than the above-described antioxidant as necessary within the range not impairing the effects of the present invention.
Examples of such other lubricating oil additives include cleaning dispersants, pour point depressants, metal deactivators, antifoaming agents, extreme pressure agents, rust inhibitors, oiliness agents, friction modifiers, And emulsifiers.
Each of these additives for lubricating oil may be used alone or in combination of two or more.
Further, among these additives for lubricating oil, a sulfur-based compound having antioxidant performance is included in “component (A)”, and an amine-based compound having antioxidant performance is included in “component (B)”.

The lubricating oil composition of the present invention preferably further contains a cleaning dispersant.
In addition, it is assumed that the content of each additive for lubricating oil is adjusted within a range that satisfies the above requirements (I) and (II), but more specific contents are added for each lubricating oil. As described in the agent section.

(Cleaning dispersant)
Examples of the cleaning dispersant include metal sulfonate, metal salicylate, metal phenate, organic phosphite, organic phosphate, organic sulfonate metal salt, organic phosphate metal salt, succinimide, benzylamine, and succinate. And polyhydric alcohol esters.
As the metal constituting the metal salt such as metal sulfonate, alkali metal and alkaline earth metal are preferable, sodium, calcium, magnesium, and barium are more preferable, and calcium is more preferable. Succinimide, benzylamine, and succinic acid are also preferable. The acid ester may be a boron-modified product.

When the lubricating oil composition of one embodiment of the present invention contains a cleaning dispersant, the content of the cleaning dispersant is preferably 0.01 to 10 based on the total mass (100% by mass) of the lubricating oil composition. It is 0.0% by mass, more preferably 0.02 to 7.0% by mass, and still more preferably 0.03 to 5.0% by mass.

(Pour point depressant)
Examples of the pour point depressant include ethylene-vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol, polymethacrylate, polyalkylstyrene and the like. . The weight average molecular weight of these polymers is preferably 50,000 to 150,000.
When the lubricating oil composition of one embodiment of the present invention contains a pour point depressant, the content of the pour point depressant is preferably 0.01 based on the total mass (100% by mass) of the lubricating oil composition. It is ˜5.0% by mass, more preferably 0.02 to 2.0% by mass.

(Metal deactivator)
Examples of the metal deactivator include benzotriazole compounds, tolyltriazole compounds, thiadiazole compounds, imidazole compounds, and pyrimidine compounds.
When the lubricating oil composition of one embodiment of the present invention contains a metal deactivator, the content of the metal deactivator is preferably 0 based on the total mass (100% by mass) of the lubricating oil composition. 0.01 to 5.0% by mass, more preferably 0.02 to 3.0% by mass.

(Defoamer)
Examples of the antifoaming agent include silicone oil, fluorosilicone oil, and fluoroalkyl ether.
When the lubricating oil composition of one embodiment of the present invention contains an antifoaming agent, the content of the antifoaming agent is preferably 0.001 to 0 based on the total mass (100% by mass) of the lubricating oil composition. .50 mass%, more preferably 0.01 to 0.30 mass%.

(Extreme pressure agent)
Examples of extreme pressure agents include phosphorous extreme pressure agents such as phosphate esters, phosphites, acidic phosphate esters, and acidic phosphites; halogen extreme pressure agents such as chlorinated hydrocarbons. Organometallic extreme pressure agents; and the like.
In addition, in the lubricating oil composition containing the compound which has a function as an extreme pressure agent as the above-mentioned antioxidant, it is not necessary to separately contain an extreme pressure agent.
When the lubricating oil composition of one embodiment of the present invention contains an extreme pressure agent, the content of the extreme pressure agent is preferably 0.01 to 10 based on the total mass (100% by mass) of the lubricating oil composition. 0.0 mass%, more preferably 0.05 to 5.0 mass%.

(anti-rust)
Examples of the rust preventive include metal sulfonate, alkylbenzene sulfonate, dinonyl naphthalene sulfonate, organic phosphite, organic phosphate, organic sulfonate metal salt, organic phosphate metal salt, and alkenyl succinate. And polyhydric alcohol esters.
When the lubricating oil composition of one embodiment of the present invention contains a rust inhibitor, the content of the rust inhibitor is preferably 0.01 to 10 on the basis of the total mass (100% by mass) of the lubricating oil composition. 0.0 mass%, more preferably 0.05 to 5.0 mass%.

(Oil-based agent)
Examples of the oily agent include aliphatic alcohols; fatty acid compounds such as fatty acids and fatty acid metal salts; ester compounds such as polyol esters, sorbitan esters, and glycerides.
When the lubricating oil composition of one embodiment of the present invention contains an oily agent, the content of the oily agent is preferably 0.1 to 5.0, based on the total mass (100% by mass) of the lubricating oil composition. % By mass.

(Friction modifier)
Examples of the friction modifier include molybdenum friction modifiers such as molybdenum dithiocarbamate (MoDTC) and molybdenum dithiophosphate (MoDTP); fat having at least one alkyl group or alkenyl group having 6 to 30 carbon atoms in the molecule. Ashless friction modifiers such as aliphatic amines, fatty acid esters, fatty acids, aliphatic alcohols, aliphatic ethers, and the like.
When the lubricating oil composition of one embodiment of the present invention contains a friction modifier, the content of the friction modifier is preferably 0.01 to 5 based on the total mass (100% by mass) of the lubricating oil composition. 0.0% by mass.

(Demulsifier)
Examples of the demulsifier include anionic surfactants such as castor oil sulfate and petroleum sulfonates; cationic surfactants such as quaternary ammonium salts and imidazolines; polyoxyalkylene polyglycols and their dicarboxylic acids An alkylene oxide adduct of an alkylphenol-formaldehyde polycondensate; and the like.
When the lubricating oil composition of one embodiment of the present invention contains a demulsifier, the content of the demulsifier is preferably 0.01 to 5.0, based on the total mass (100% by mass) of the lubricating oil composition. % By mass, more preferably 0.02 to 2.0% by mass.

<Physical properties of lubricating oil composition>
The kinematic viscosity at 40 ° C. of the lubricating oil composition of one embodiment of the present invention is preferably 10 to 100 mm ² / s, more preferably 20 to 70 mm ² / s, still more preferably 30 to 50 mm ² / s.

The viscosity index of the lubricating oil composition of one embodiment of the present invention is preferably 60 or more, more preferably 75 or more, and still more preferably 90 or more.

The acid value of the lubricating oil composition of one embodiment of the present invention is preferably 0.00 to 1.00 mg KOH / g, more preferably 0.00 to 1.00 mg KOH / g, and still more preferably 0.00 to 1. 00 mg KOH / g.
In the present specification, the acid value of the lubricating oil composition means a value measured according to JIS K2501: 2003.

Since the lubricating oil composition of the present invention has excellent oxidation stability, it effectively suppresses adverse effects such as an increase in acid value and kinematic viscosity, a decrease in cleanliness, and an increase in the amount of sludge due to long-term use. Can do.
In the lubricating oil composition of one embodiment of the present invention, when the modified Indiana Oxidation Stability Test based on the measurement conditions described in the examples is performed for 120 hours, the acid value of the lubricating oil composition increases. The amount ([acid value after test] − [acid value before test]) is preferably 1.00 mgKOH / g or less, more preferably 0.50 mgKOH / g or less, still more preferably 0.10 mgKOH / g or less. More preferably, it is 0.05 mgKOH / g or less.

In the lubricating oil composition of one embodiment of the present invention, the ratio of the kinematic viscosity before and after the test at 40 ° C. when the modified Indiana oxidation test based on the measurement conditions described in the examples was performed for 120 hours ([post-test Kinematic viscosity at 40 ° C.] / [Kinematic viscosity at 40 ° C. before the test]] is preferably 1.30 or less, more preferably 1.25 or less, still more preferably 1.20 or less, and even more preferably 1. 15 or less.

In the lubricating oil composition of one embodiment of the present invention, the Millipore value (precipitate amount) per 100 ml of the lubricating oil composition when the modified Indiana oxidation test based on the measurement conditions described in the examples is performed for 120 hours is preferably Is 4.0 mg / 100 ml or less, more preferably 2.5 mg / 100 ml or less, still more preferably 2.0 mg / 100 ml or less, still more preferably 1.0 mg / 100 ml or less.
In the present specification, the Millipore value means a value measured according to SAE-ARP-785-63: 1996.

In the lubricating oil composition of one embodiment of the present invention, the amount of deposit per 100 ml of the lubricating oil composition when the panel coking test based on the measurement conditions described in the examples is performed for 120 hours is preferably 20 mg / 100 ml or less. More preferably, it is 15 mg / 100 ml or less, More preferably, it is 10 mg / 100 ml or less, More preferably, it is 5 mg / 100 ml or less.

<Use of lubricating oil composition>
The lubricating oil composition of the present invention has a high effect of suppressing oxidative degradation associated with long-term use, and has excellent oxidation stability.
Therefore, the lubricating oil composition of the present invention is suitable for applications that are used in harsh environments and requires high oxidation stability, and is particularly preferably used for a rotary compressor.
That is, this application also provides the usage method of the lubricating oil composition which uses the above-mentioned lubricating oil composition of this invention for a rotary compressor.

The rotary compressor using the lubricating oil composition of the present invention is excellent in terms of resource saving, high efficiency, and durability.
Examples of the rotary compressor include a screw type, a movable blade type, a scroll type, a tooth type, and a gear drive type.
Examples of the gas used in the rotary compressor include air, nitrogen gas, oxygen gas, hydrogen gas, ammonia gas, carbon dioxide gas, carbon monoxide gas, and various hydrocarbon gases.

[Lubricating oil composition for screw type air compressor]
The lubricating oil composition of the present invention is particularly preferably used as a lubricating oil composition for a screw type air compressor.
That is, the present invention provides a "lubricant for a screw type air compressor that includes a sulfur-based antioxidant (A) and an amine-based antioxidant (B) together with a base oil and satisfies the following requirements (I) and (II): Also provided are “composition” and “method of using the lubricating oil composition, wherein the lubricating oil composition is used in a screw-type air compressor”.
Requirement (I): The total content of sulfur atoms and nitrogen atoms is 0.010 to 0.600% by mass based on the total mass of the lubricating oil composition for a screw type air compressor.
Requirement (II): The content ratio of sulfur atom to nitrogen atom [sulfur atom / nitrogen atom] is 0.45 to 20.00 by mass ratio.

In the lubricating oil composition for a screw-type air compressor of the present invention, the base oil, component (A), component (B), and other additives for lubricating oil used in the above steps, and the above requirement (I) And the matter regarding (II) is as having described in the above-mentioned item of "the lubricating oil composition of the present invention".
Moreover, the preferable range of various physical properties of the lubricating oil composition for a screw type air compressor of the present invention is also the same as the description in the above item “Lubricating oil composition of the present invention”.

The screw type air compressor using the lubricating oil composition for the screw type air compressor of the present invention is excellent in terms of resource saving, high efficiency, and durability.

[Method for producing lubricating oil composition]
The method for producing a lubricating oil composition of the present invention is a step of blending a sulfur-based antioxidant (A) and an amine-based antioxidant (B) into a base oil so as to satisfy the following requirements (I) and (II). Have
Requirement (I): The total content of sulfur atoms and nitrogen atoms is 0.010 to 0.600 mass% based on the total mass of the lubricating oil composition.
Requirement (II): The content ratio of sulfur atom to nitrogen atom [sulfur atom / nitrogen atom] is 0.45 to 20.00 by mass ratio.

In the method for producing a lubricating oil composition of the present invention, the base oil, component (A), component (B), and other additives for lubricating oil used in the above steps, and the above requirements (I) and (II) ) Are as described in the item "Lubricating oil composition of the present invention" above.
The preferred range of physical properties of the lubricating oil composition obtained by the method for producing a lubricating oil composition of the present invention and the use of the lubricating oil composition are also described in the above-mentioned section “Lubricating oil composition of the present invention”. Is the same.

In the above step, after blending the components (A) and (B) and other additives for lubricating oil added as necessary, the base oil is stirred into a base oil by a known method. It is preferable to uniformly disperse the additive containing the components (A) and (B).
Further, from the viewpoint of uniformly dispersing the additive containing components (A) and (B) in the base oil, the base oil is heated (for example, 40 to 60 ° C.), and then these additives are blended and stirred. It is preferable to do.

In addition, after mix | blending component (A) and (B) with base oil, a part of component (A) and / or component (B) modified | denatured, or it reacted with another component and produced | generated another component. Even so, the obtained lubricating oil composition corresponds to the lubricating oil composition obtained by the method for producing a lubricating oil composition of the present invention, and belongs to the technical scope of the present invention.

EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not restrict | limited at all by these examples.
Various physical properties of the base oil and the lubricating oil composition were measured based on the following methods.
(1) 40 ° C. kinematic viscosity, 100 ° C. kinematic viscosity Measured according to JIS K2283: 2000.
(2) Viscosity index Measured according to JIS K2283: 2000.
(3) Density at 15 ° C. Measured according to JIS K2249: 2011.
(4) Acid value (indicator method)
Measured according to JIS K2501: 2003.
(5) Sulfur atom content Measured according to JIS K2541-6: 2013.
(6) Content of nitrogen atom It measured based on JISK2609: 1998.
(7) Content of phosphorus atom Measured according to JPI-5S-38-92.

Examples 1-9, Comparative Examples 1-5
(1) Preparation of lubricating oil composition Lubricating oil compositions (1a) to (9a) and (1b) containing the base oil, antioxidant, and other additives of the types and blending amounts shown in Table 1 To (5b) were prepared respectively.
Details of the base oils, antioxidants, and other additives used in the examples and comparative examples shown in Table 1 are as follows.

<Base oil>
・ Base oil 1:
Paraffinic mineral oils (hydrogenated Kaaratame quality oil), 40 ° C. kinematic viscosity = 30.9mm ² / s, 100 ℃ kinematic viscosity = 5.35mm ² / s, viscosity index = 106,15 ℃ Density = 0.863 g / cm ³ .
・ Base oil 2:
Paraffin-based mineral oil (hydrogenated modified oil), 40 ° C. kinematic viscosity = 90.5 mm ² / s, 100 ° C. kinematic viscosity = 10.89 mm ² / s, viscosity index = 105, 15 ° C. density = 0.8692 g / cm ³ .
・ Base oil 3:
Poly α-olefin, 40 ° C. kinematic viscosity = 28.8 mm ² / s, 100 ° C. kinematic viscosity = 5.6 mm ² / s, viscosity index = 137, 15 ° C. density = 0.826 g / cm ³ .
・ Base oil 4:
Poly α-olefin, 40 ° C. kinematic viscosity = 46.7 mm ² / s, 100 ° C. kinematic viscosity = 7.84 mm ² / s, viscosity index = 138, 15 ° C. density = 0.830 g / cm ³ .
・ Base oil 5:
2-ethylhexyl trimellitic acid, 40 ° C. kinematic viscosity = 90.0 mm ² / s, 100 ° C. kinematic viscosity = 9.52 mm ² / s, viscosity index = 78, 15 ° C. density = 0.993 g / cm ³ .
・ Base oil 6:
Polyalkylene glycol, 40 ° C. kinematic viscosity = 45.6 mm ² / s, 100 ° C. kinematic viscosity = 9.65 mm ² / s, viscosity index = 204, 15 ° C. density = 0.9956 g / cm ³ .

<Antioxidant>
・ Sulfur-based antioxidant (A-1):
2,6-di-t-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol, sulfur atom (S) content = 10.9% by mass, Nitrogen atom (N) content = 10.2% by mass.
・ Sulfur-based antioxidant (A-2):
O, O, O-triphenyl phosphorothioate, sulfur atom (S) content = 9.3 mass%, phosphorus atom (P) content = 8.9 mass%.
Amine-based antioxidant (B-1):
Dioctyldiphenylamine, nitrogen atom (N) content = 3.6 mass%.
・ Amine antioxidant (B-2):
4,4′-bis (α, α-dimethylbenzyl) diphenylamine, nitrogen atom (N) content = 3.45% by mass.
・ Amine antioxidant (B-3):
t-Octylphenyl-1-naphthylamine, nitrogen atom (N) content = 8.48% by mass.
・ Phenolic antioxidant (C-1):
Octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, molecular weight = 530.
・ Phenolic antioxidant (C-2):
Diethyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate, molecular weight = 354, phosphorus atom (P) content = 8.8% by mass.

<Other additives>
Pour point depressant: polymethacrylate, weight average molecular weight = 69,000.
-Clean dispersant (1): Calcium salicylate.
Clean dispersant (2): calcium sulfonate, sulfur atom (S) content = 2.7% by mass.
Metal deactivator: N-dialkylaminomethylbenzotriazole, nitrogen atom (N) content = 14.6% by mass.
-Antifoaming agent: Silicone antifoaming agent.

[Supplement under rule 26 21.04.2016]

The lubricating oil compositions prepared in Examples and Comparative Examples were subjected to the tests shown in the following (1) to (3) after measuring the acid value, 40 ° C. kinematic viscosity, and viscosity index before various tests. It was. These results are shown in Table 2.

(1) Modified Indiana Oxidation Test Put 300 mL of the lubricating oil composition prepared in a glass tube without enclosing water, and use a 7.0 mm outer diameter blow tube with a diffuser stone at the tip. The test was performed by inserting the glass tube so as to be immersed in the lubricating oil composition and blowing in oxygen from the blowing tube at a flow rate of 3 L / h for a maximum of 120 hours at an oil temperature of 130 ° C. In this test, various conditions other than the above were based on JIS K2514-2.
Samples of the lubricating oil composition after 72 hours, 96 hours, and 120 hours after the start of the blowing of oxygen were taken, the acid value of each sample was measured, and the acid value of the lubricating oil composition before the test was measured. The amount of increase was calculated. (In Comparative Examples 3 and 5, measurement of the acid value of the sample after 72 hours was omitted, and in Comparative Examples 1 and 6, measurement of the acid value of the sample after 120 hours was omitted.)
In addition, samples of the lubricating oil composition 96 hours or 120 hours after the start of blowing oxygen were collected, and the kinematic viscosity at 40 ° C. of each sample was also measured.

(2) Millipore filter test According to SAE-ARP-785-63: 1996, in a 300 mL lubricating oil composition 96 hours or 120 hours after the start of blowing oxygen collected during the modified Indiana oxidation test. The precipitate was collected by filtration, and its mass was measured as a millipore value. In Table 2, the millipore value (precipitate amount) per 100 mL of the lubricating oil composition is described.

(3) Panel coking test 300 mL of the lubricating oil composition prepared in a heating tank was placed and heated to 100 ° C. Then, the operation of splashing the lubricating oil composition heated to 100 ° C. with the blades continuously rotated at a speed of 1000 rpm on the aluminum plate heated to 260 ° C. installed in the upper part of the heating tank for 96 hours Or it continued for 120 hours, and the mass of the deposit adhering to the aluminum plate was measured after the said time progress. In Table 2, the deposit amount per 100 mL of the lubricating oil composition is described.

[Supplement under rule 26 21.04.2016]

According to Table 2, the lubricating oil compositions (1a) to (9a) prepared in Examples 1 to 9 were compared with the lubricating oil compositions (1b) to (5b) prepared in Comparative Examples 1 to 5, In the modified Indiana oxidation test for 120 hours at high temperatures, the results of effective suppression of adverse effects caused by oxidative degradation such as increase in acid value and kinematic viscosity, increase in sludge amount, and adhesion of the sludge to equipment and filters It became.
Therefore, it can be seen that the lubricating oil composition of the present invention maintains high oxidation stability over a long period of time.

Claims (15)

1. A lubricating oil composition comprising a base oil, a sulfur-based antioxidant (A), and an amine-based antioxidant (B) and satisfying the following requirements (I) and (II).
   Requirement (I): The total content of sulfur atoms and nitrogen atoms is 0.010 to 0.600 mass% based on the total mass of the lubricating oil composition.
   Requirement (II): The content ratio of sulfur atom to nitrogen atom [sulfur atom / nitrogen atom] is 0.45 to 20.00 by mass ratio.
2. The component (A) includes at least one selected from a compound (A1) containing no sulfur atom and containing a sulfur atom, and a compound (A2) containing a phosphorus atom and a sulfur atom. Lubricating oil composition.
3. The lubricating oil composition according to claim 2, wherein the component (A) includes both the compound (A1) and the compound (A2).
4. 4. The lubricating oil composition according to claim 2, wherein the content ratio of phosphorus atom to sulfur atom [phosphorus atom / sulfur atom] is 0.01 to 2.00 in terms of mass ratio.
5. The lubricating oil composition according to any one of claims 1 to 4, further comprising a phenolic antioxidant (C).
6. The lubricating oil composition according to claim 5, wherein the molecular weight of component (C) is 250 or more.
7. The content ratio [(A) / (B)] of the component (A) and the component (B) is 0.40 to 20.00 by mass ratio, according to any one of claims 1 to 6. The lubricating oil composition described.
8. The total content of antioxidants contained in the lubricating oil composition is 0.01 to 10.00% by mass based on the total mass of the lubricating oil composition. The lubricating oil composition according to Item.
9. The lubricating oil composition according to any one of claims 1 to 8, further comprising a cleaning dispersant.
10. The lubricating oil composition according to any one of claims 1 to 9, wherein the base oil is at least one selected from mineral oil and synthetic oil.
11. The lubricating oil composition according to any one of claims 1 to 10, wherein the base oil has a kinematic viscosity at 40 ° C of 10 to 200 mm ² / s.
12. A method for using a lubricating oil composition, wherein the lubricating oil composition according to any one of claims 1 to 11 is used in a rotary compressor.
13. The method for using a lubricating oil composition according to claim 12, wherein the rotary compressor is a screw type air compressor.
14. A rotary compressor using the lubricating oil composition according to any one of claims 1 to 11.
15. The manufacturing method of a lubricating oil composition which has a process which mix | blends sulfur type antioxidant (A) and amine type antioxidant (B) with base oil so that the following requirements (I) and (II) may be satisfy | filled.
    Requirement (I): The total content of sulfur atoms and nitrogen atoms is 0.010 to 0.600 mass% based on the total mass of the lubricating oil composition.
    Requirement (II): The content ratio of sulfur atom to nitrogen atom [sulfur atom / nitrogen atom] is 0.45 to 20.00 by mass ratio.