JP2001348590A - Lubricating oil composition - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To be used under high temperature conditions, such as industrial circulating system oils such as hydraulic fluids and gear oils, as well as having high thermal and oxidation stability and excellent wear and seizure resistance. The present invention provides a lubricating oil composition that can suppress seizure of a mechanical sliding portion and generation of sludge for a long period of time even when the lubricating oil composition is used. SOLUTION: At least one kind selected from the group consisting of mineral oils, fats and oils and synthetic oils is used as a base oil, and the following compound (A)
-(D): (A) alkylphenol, (B) aromatic phosphate, (C) alkyl thiadiazole, and (D) at least one selected from the group consisting of alkali metals, alkaline earth metals, zinc and lead. A lubricating oil composition comprising an organic acid salt of a metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating oil composition, and more particularly, to a lubricating oil composition suitably used under high-temperature conditions such as industrial circulating system oil.

[0002]

2. Description of the Related Art In recent years, in various machines such as industrial machines, due to the miniaturization of lubricating oil tanks or the rigor of operating conditions for the purpose of improving production efficiency, industrial machines such as hydraulic oils and gear oils have been developed. The temperature of the circulation system oil tends to rise during machine use. In general, if the temperature of the lubricating oil rises, problems such as seizure in the sliding parts of the machine and blockage of the pipe due to the generation of sludge in the oil are likely to occur. , Especially high seizure resistance and abrasion resistance are required. In addition, the oxidative stability of the lubricating oil decreases as the temperature rises, so the use of the lubricating oil under high temperature conditions tends to shorten its life, but from the viewpoint of reducing production costs, the lubricating oil has a longer life. It is also required to have a lifetime.

In order to solve these problems, lubricating oil compositions containing various additives have been proposed. JP-A-11-209776 discloses a lubricating oil composition in which a phosphoric acid ester or an amine salt thereof, a sulfur-based extreme pressure agent, and an amine-based antioxidant and / or a phenol-based antioxidant are blended with a lubricating base oil. A technology relating to an object is disclosed. However, since the anti-seizure property under high-temperature conditions and the thermal / oxidative stability of the lubricating oil composition have a reciprocal relationship, even when such a lubricating oil composition is used, the anti-seizure property or the thermal / oxidative stability is obtained. Either of the stability became insufficient, and it was difficult to maintain these required performances for a long period of time.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has excellent heat / oxidation stability, sufficiently high abrasion resistance and seizure resistance, and has a high hydraulic pressure. Lubricating oil that can suppress seizure of machine sliding parts and generation of sludge for a long period of time even when used under high temperature conditions such as industrial circulating system oil such as hydraulic oil and gear oil It is intended to provide a composition.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a specific lubricating base oil has an alkylphenol, an aromatic phosphate, an alkylthiadiazole and a metal organic acid salt. The present inventors have found that a lubricating oil composition having excellent heat and oxidation stability and having sufficiently high seizure resistance and abrasion resistance can be obtained by incorporating the same in combination, thereby completing the present invention.

That is, the lubricating oil composition of the present invention comprises at least one selected from the group consisting of mineral oils, fats and oils, and synthetic oils as base oils, and comprises the following compounds (A) to (D): (A) alkylphenol, (B) an aromatic phosphate, (C) an alkyl thiadiazole, and (D) an organic acid salt of at least one metal selected from the group consisting of alkali metals, alkaline earth metals, zinc and lead. It is assumed that.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.

[0008] In the lubricating oil composition of the present invention, mineral oil,
Fats or synthetic oils are used.

Here, as the mineral oil, solvent removal, solvent extraction, hydrocracking, solvent dewaxing, and contact dewaxing are performed on the lubricating oil fraction obtained by distilling crude oil under normal pressure and reduced pressure. And paraffinic or naphthenic mineral oils obtained by appropriately combining one or more purification means such as hydrorefining, sulfuric acid washing, and clay treatment.

The fats and oils include beef tallow, lard, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil, and hydrogenated products thereof.

Further, as the synthetic oil, poly-α-olefins (ethylene-propylene copolymer, polybutene, 1-octene oligomer, 1-decene oligomer,
And hydrides thereof), alkyl benzene, alkyl naphthalene, monoester (butyl stearate, octyl laurate), diester (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-
2-ethylhexyl sepacate, etc.), polyester (such as trimellitate), polyol ester (trimethylolpropane caprylate, trimethylolpropaneperargonate, pentaerythritol-2)
-Ethylhexanoate, pentaerythritol pelargonate, etc.), polyoxyalkylene glycol, polyphenyl ether, dialkyl diphenyl ether,
Phosphate esters (tricresyl phosphate, etc.),
Examples include fluorinated compounds (such as perfluoropolyethers and fluorinated polyolefins), silicone oils and the like.

In the present invention, one of the above base oils may be used alone, or two or more may be used in combination.

Although the viscosity of the base oil used in the present invention is not particularly limited, the kinematic viscosity of the base oil at 40 ° C. is 800
mm2 / s or less, preferably 500 mm2 / s
More preferably, it is not more than s. When the kinematic viscosity at 40 ° C. of the base oil exceeds the upper limit, lubricating oil supply properties in various machines tend to be insufficient. The kinematic viscosity of the base oil at 40 ° C. is preferably 1.0 mm 2 / s or more, more preferably 1.5 mm 2 / s or more. If the viscosity of the base oil at 40 ° C. is less than the lower limit, volatility is increased and safety is reduced, and the lubricating film is thinned and the sliding surface tends to seize.

The content of the base oil in the lubricating oil composition of the present invention is not particularly limited, but is preferably at least 60% by mass, more preferably at least 32% by mass based on the total amount of the lubricating oil composition. When the content of the base oil is less than the lower limit, the storage stability of the additive tends to decrease. The amount of the base oil is 99.96% by mass or less based on the total amount of the lubricating oil composition.
More preferably, the content is 99.90% by mass or less. If the content of the base oil exceeds the above upper limit, the friction characteristics and the thermal and oxidative stability tend to be insufficient.

In the lubricating oil composition of the present invention, the base oil described above contains the following compounds (A) to (D): (A) an alkylphenol, (B) an aromatic phosphate, (C) an alkyl thiadiazole, and D) An organic acid salt of at least one metal selected from the group consisting of alkali metals, alkaline earth metals, zinc and lead is blended.

The type of the alkylphenol used as the component (A) of the present invention is not particularly limited, and any alkylphenol compound conventionally used as an antioxidant for lubricating oils can be used. General formula (1) or (4):

[0017]

Embedded image [Wherein, R ¹ represents an alkyl group having 1 to 4 carbon atoms, R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ³
Is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or the following formula (2) or (3):

Embedded image

[0018]

Embedded image (Wherein, R ⁴ represents an alkylene group having 1 to 6 carbon atoms, R ⁵
Represents an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 1 to 24 carbon atoms, R ⁶ represents an alkylene group having 1 to ⁶ carbon atoms, R ⁷ represents an alkylene group having 1 to 4 carbon atoms,
R ⁸ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms).

[0019]

Embedded image [Wherein, R ⁹ and R ¹⁰ may be the same or different, each represents an alkyl group having 1 to 4 carbon atoms, and R ¹¹ and R ¹² may be the same or different, and each represents a hydrogen atom or a carbon atom. Represents an alkyl group of 1 to 4, R ¹³ and R ¹⁴ may be the same or different, and have 1 carbon atom.
And Y represents an alkylene group having 1 to 18 carbon atoms or the following formula (5):

Embedded image (Wherein, R ¹⁵ and R ¹⁶ may be the same or different and each represents an alkylene group having 1 to 6 carbon atoms) and represents an alkylphenol compound represented by the formula: Preferably, it is used.

Here, R ¹ in the above formula (1) is:
Specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-
Butyl, tert-butyl and the like.
It is preferable that ¹ is a tert-butyl group because of its excellent oxidation stability. Further, as R ² , a hydrogen atom or an alkyl group having 1 to 4 carbon atoms exemplified in the description of R ¹ can be mentioned, but it is excellent in oxidation stability that R ² is a methyl group or a tert-butyl group. It is preferred in that respect.

Examples of the alkyl group having 1 to 4 carbon atoms for R ³ include a methyl group, an ethyl group and an n-
Examples thereof include a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. It is preferable that R ³ is a methyl group or an ethyl group in terms of excellent oxidation stability. Among such alkylphenols, particularly preferred are 2,
6-di-tert-butyl-p-cresol, 2,6-
Di-tert-butyl-4-ethylphenol or a mixture thereof.

Further, the alkylene group having 1 to 6 carbon atoms represented by R ⁴ in the above formula (2) may be linear or branched. Specific examples of such an alkylene group include a methylene group, a methylmethylene group, an ethylene group (dimethylene group), an ethylmethylene group, a propylene group (methylethylene group), a trimethylene group, and a linear or branched butylene. Groups, linear or branched pentylene groups, linear or branched hexylene groups, and the like. Among these alkylene groups, alkylene groups having 1 to 2 carbon atoms,
More specifically, a methylene group, a methylmethylene group, or an ethylene group (dimethylene group) is preferable because the compound represented by the above formula (1) can be produced in a small number of reaction steps.

Further, as the alkyl group having 1 to 24 carbon atoms represented by R ⁵ in the above formula (2), a methyl group,
Ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group,
Undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henycosyl group, docosyl group, tricosyl group, tetracosyl group, etc. And alkenyl groups having 1 to 24 carbon atoms include vinyl, propenyl, isopropenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, and decenyl groups. , Undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, octadecenyl group, octadecadienyl group, nonadecenyl group, icosenyl group, henicocenyl group, dococenyl group,
Tricosenyl group, tetracosenyl group and the like (these alkenyl groups may be linear or branched, and the position of the double bond is arbitrary). Among these,
An alkyl group having 4 to 18 carbon atoms, specifically, for example, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecy, tridecyl, tetradecyl, pentadecyl , An alkyl group such as a hexadecyl group, a heptadecyl group or an octadecyl group (the alkyl group may be linear or branched), more preferably a linear or branched alkyl group having 6 to 12 carbon atoms. And a branched alkyl group having 6 to 12 carbon atoms is particularly preferred. When R ⁵ is an alkyl group having 4 to 18 carbon atoms, they tend to be improved solubility base oil alkylphenol.

In the group represented by the above formula (2), R ⁴
And R ⁵ are preferably a combination 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, and R ⁷ is 1 to
2 alkylene groups and those in which R ⁸ is a branched alkyl group having 6 to 12 carbon atoms are particularly preferred. Specific examples of such an alkylphenol include (3-methyl-5-
tert-butyl-4-hydroxyphenyl) acetic acid n-
Hexyl, (3-methyl-5-tert-butyl-4-
Isohexyl (hydroxyphenyl) acetate, n-heptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, isoheptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate,
N-octyl methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-tert-
Butyl-4-hydroxyphenyl) isooctyl acetate,
2-ethylhexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5
-Tert-butyl-4-hydroxyphenyl) acetic acid n
-Nonyl, (3-methyl-5-tert-butyl-4-
(Hydroxyphenyl) isononyl acetate, (3-methyl-
N-decyl 5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-tert-butyl-4)
-Hydroxyphenyl) isodecyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetic acid n-undecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isoundecyl acetate,
N-Dodecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-te
(rt-butyl-4-hydroxyphenyl) isododecyl acetate, n-hexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) Isohexyl propionate, (3-methyl-5-t
n-heptyl tert-butyl-4-hydroxyphenyl) propionate, isoheptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) ) N-octyl propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl)
Isooctyl propionate, (3-methyl-5-ter
t-butyl-4-hydroxyphenyl) propionic acid 2
-Ethylhexyl, n-nonyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, isononyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl- N-decyl 5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-
Isodecyl (butyl-4-hydroxyphenyl) propionate, n-undecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-
Isoundecyl methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5
n-dodecyl tert-butyl-4-hydroxyphenyl) propionate, isododecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) ) N-hexyl acetate, (3,5-di-tert)
-Butyl-4-hydroxyphenyl) acetic acid isohexyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid n-heptyl, (3,5-di-tert)
-Butyl-4-hydroxyphenyl) acetate isoheptyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-octyl, (3,5-di-tert)
-Butyl-4-hydroxyphenyl) acetic acid isooctyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid 2-ethylhexyl, (3,5-di-t
n-nonyl tert-butyl-4-hydroxyphenyl) acetate, isononyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di-tert)
-Butyl-4-hydroxyphenyl) n-decyl acetate;
Isodecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, n-undecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate,
(3,5-di-tert-butyl-4-hydroxyphenyl) isoundecyl acetate, (3,5-di-tert-butyl)
Butyl-4-hydroxyphenyl) n-dodecyl acetate;
Isododecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, n-hexyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert- Isohexyl butyl-4-hydroxyphenyl) propionate, n-heptyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) propion Isoheptyl acid, n-octyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-
tert-butyl-4-hydroxyphenyl) isooctyl propionate, (3,5-di-tert-butyl-
2-ethylhexyl 4-hydroxyphenyl) propionate, n-nonyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-
tert-butyl-4-hydroxyphenyl) isononyl propionate, (3,5-di-tert-butyl-4)
-Hydroxyphenyl) n-decyl propionate,
(3,5-di-tert-butyl-4-hydroxyphenyl) isodecyl propionate, (3,5-di-tert-butyl)
t-butyl-4-hydroxyphenyl) propionic acid n
-Undecyl, (3,5-di-tert-butyl-4-
(Hydroxyphenyl) isoundecyl propionate,
(3,5-di-tert-butyl-4-hydroxyphenyl) n-dodecyl propionate, (3,5-di-te
rt-butyl-4-hydroxyphenyl) isododecyl propionate, and mixtures thereof.

On the other hand, in the group represented by the above formula (3), the alkylene group having 1 to 6 carbon atoms represented by R ⁶ may be linear or branched. Specific examples of such an alkylene group include the alkylene groups having 1 to 6 carbon atoms exemplified for R ⁷ above,
R ⁶ is an alkylene group having 1 to 3 carbon atoms, more specifically,
The methylene group, methylmethylene group, ethylene group (dimethylene group), ethylmethylene group, propylene group (methylethylene group), and trimethylene group are represented by the above formula (1).
Is preferable in that it can be produced in a reaction step in which the amount of the alkylphenol represented by the formula is small, and the raw materials thereof are easily available.

The alkyl group having 1 to 6 carbon atoms represented by R ⁷ in the above formula (3) includes, specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n-
Butyl group, isobutyl group, sec-butyl group, tert
-Butyl group and the like, and it is preferable that R ⁷ is a tert-butyl group in terms of excellent oxidation stability. As the R ^8, specifically, there may be mentioned an alkyl group having 1 to 4 carbon atoms exemplified in the description of R ¹ a hydrogen atom or the above formula (1) in, R ⁸ is a methyl group or a te
An rt-butyl group is preferred from the viewpoint of excellent oxidation stability.

Preferred examples of the compound in which R ⁶ is a group represented by the formula (3) among the alkylphenols represented by the general formula (1) 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, 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,
2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, and mixtures thereof.

On the other hand, in the above formula (4), examples of the alkyl group having 1 to 4 carbon atoms represented by R ⁹ and R ¹⁰ include a methyl group, an ethyl group, an n-propyl group and an isopropyl group. , n- butyl group, isobutyl group, sec- butyl group, and tert- butyl group, R ⁹
It is preferred that R ¹⁰ and R ¹⁰ are both tert-butyl groups from the viewpoint of oxidation stability.

Examples of the groups represented by R ¹¹ and R ¹² include a hydrogen atom and an alkyl group having 1 to 4 carbon atoms exemplified in the description of R ^{1 in} the above formula (1). ^{1 1} and R ¹² are each methyl or tert
A -butyl group is preferred in that it has excellent oxidation stability. In this case, R ¹¹ and R ¹² may be the same or different.

Further, the alkylene group having 1 to 6 carbon atoms represented by R ¹³ and R ¹⁴ may be linear or branched. Specific examples of such an alkylene group include those having 1 carbon atom as exemplified in the description of R ^{4 in} the above formula (2).
And R ¹³ and R ¹⁴ are each an alkylene group having 1 to 2 carbon atoms, more specifically, a methylene group, a methylmethylene group or an ethylene group (dimethylene group), This is preferable in that the alkylphenol represented by the above formula (4) can be produced in a small number of reaction steps and that the raw materials thereof are easily available. In this case, R ¹³ and R ¹⁴ may be the same or different.

When the group represented by Y is an alkylene group having 1 to 18 carbon atoms, specific examples of the alkylene group include a methylene group, a methylmethylene group, an ethylene group (dimethylene group), Ethylmethylene group, propylene group (methylethylene group), trimethylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group,
A dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, an octadecylene group and the like (these alkylene groups may be linear or branched); An alkylene group, more specifically, a methylene group,
Methylmethylene group, ethylene group (dimethylene group), ethylmethylene group, propylene group (methylethylene group), trimethylene group, butylene group, pentylene group, hexylene group, etc. (The alkylene groups may be linear or branched. ) Is preferable from the viewpoint of easy availability of raw materials and the like, and ethylene group (dimethylene group), trimethylene group,
More preferably, it is a straight-chain alkylene group having 2 to 6 carbon atoms such as a straight-chain butylene group (tetramethylene group, straight-chain pentylene group (pentamethylene group), straight-chain hexylene group (hexamethylene group). Particularly preferred alkylphenols are those represented by the following formula (6):

[0032]

Embedded image It is a compound represented by these.

On the other hand, Y in the above equation (4) is equal to the above equation (5).
In the case of a group represented by the formula: R ¹⁵ and R ¹⁶ in the formula (5)
The alkylene group having 1 to 6 carbon atoms represented by may be linear or branched. Such alkylene groups, specifically, the formula (2) is an alkylene group having 1 to 6 carbon atoms which is exemplified in the description of R ⁴ in the like, the number of carbon atoms of R ¹⁵ and R ¹⁶ are each 1 to 3 alkylene groups, more specifically, a methylene group, a methylmethylene group, an ethylene group (dimethylene group), an ethylmethylene group,
A propylene group (methylethylene group) and a trimethylene group are preferable in that raw materials used for producing the alkylphenol of the above formula (4) are easily available. Among these alkyl phenols, particularly preferred are those represented by the following formula (7):

[0034]

Embedded image It is a compound represented by these.

The content of the component (A) (alkylphenol) in the lubricating oil composition of the present invention is not particularly limited.
It is preferably at most 10% by mass, more preferably at most 7% by mass, further preferably at most 5% by mass, most preferably at most 2% by mass, based on the total amount of the composition. When the content of the component (A) is more than 10% by mass, it is difficult to further improve the abrasion resistance corresponding to the content, and the storage stability tends to deteriorate. The content of the component (A) is preferably 0.01 to 0.01% based on the total amount of the composition.
% Or more, more preferably 0.02% or more, still more preferably 0.05% or more, and most preferably 0.1% or more.
1% by mass or more. When the content of the component (A) is less than 0.01% by mass, it is difficult to improve the wear resistance by adding the component, and the thermal / oxidative stability of the lubricating oil composition tends to deteriorate. .

The aromatic phosphate which is the component (B) of the lubricating oil composition of the present invention specifically includes triaryl phosphate, diaryl phosphate and monoaryl phosphate.

As the above triaryl phosphate,
The following general formula (8):

Embedded image [In the formula, Ar ¹ , Ar ² and Ar ³ may be the same or different and each represents a phenyl group, a naphthyl group or an alkylaryl group having 7 to 18 carbon atoms, and X ¹ , X ² ,
X ³ and X ⁴ may be each independently or different;
Represents an oxygen atom or a sulfur atom]. Here, as the alkylaryl group, a tolyl group (the bonding position of the methyl group to the benzene ring is arbitrary), a xylyl group (the bonding position of each methyl group to the benzene ring is arbitrary), an ethylphenyl group (The bonding position of the ethyl group to the benzene ring is arbitrary), the methylethylphenyl group (the bonding position of the methyl group and the ethyl group to the benzene ring is arbitrary), the diethylphenyl group (the bonding position of each ethyl group to the benzene ring) Is optional.), Propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group,
Examples thereof include an undecylphenyl group and a dodecylphenyl group (the alkyl group in the monoalkylphenyl group may be linear or branched, and the position of the alkyl group bonded to the benzene ring is arbitrary).

Among the triaryl phosphates represented by the above formula (8), Ar ¹ , Ar ² and Ar ³ are each a phenyl group or an alkylaryl group having 7 to 10 carbon atoms, and X ¹ , X ² , X 3 Compounds in which ³ and X ⁴ are each an oxygen atom are preferred in that they can impart excellent wear resistance to the lubricating oil composition. Specific examples of such triaryl phosphates include triphenyl phosphate, tricresyl phosphate, monocresyl diphenyl phosphate, dicresyl monophenyl phosphate, triphenyl thiophosphate, tricresyl thiophosphate, and monocresyl diphenylthio. Phosphate, dicresyl monophenyl thiophosphate or a mixture thereof, and the like can be mentioned, and among these, triphenyl phosphate, tricresyl phosphate, monocresyl diphenyl phosphate, dicresyl monophenyl phosphate, a mixture thereof, and the like are particularly preferable.

The diaryl phosphate is represented by the following general formula (9):

Embedded image [Wherein, R ¹⁷ represents an aliphatic hydrocarbon group having 1 to 24 carbon atoms or an alicyclic hydrocarbon group having 1 to 24 carbon atoms, and Ar ⁴ and Ar ⁵ may be the same or different; X ⁵ , X ⁶ , X ⁷ and X ⁸ may be the same or different, and each represents an oxygen atom or a sulfur atom], a naphthyl group or an alkylaryl group having 7 to 18 carbon atoms. Compounds are preferably used.

Here, as the aliphatic hydrocarbon group,
Methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group,
a tert-butyl group, a linear or branched pentyl group, a linear or branched hexyl group, a linear or branched heptyl group, a linear or branched octyl group, a linear or branched nonyl group, Linear or branched decyl group, linear or branched undecyl group, linear or branched dodecyl 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, linear or branched icosyl group, linear or branched henicosasyl group, linear or branched docosyl group, linear or branched Alkyl groups such as a tricosyl group, a linear or branched tetracosyl group; a vinyl group, a linear or branched propenyl group, a linear or branched butenyl group, a linear or branched pentenyl group, a linear group Or a branched hexenyl group, a linear or branched heptenyl group, a linear or branched octenyl group, a linear or branched nonenyl group, a linear or branched decenyl group, a linear or branched undecenyl group Group, straight or branched dodecenyl group, straight or branched tridecenyl group, straight or branched tetradecenyl group, straight or branched hexadecenyl group, straight or branched heptadecenyl group Group, straight or branched octadecenyl group, straight or branched nonadecenyl group, straight or branched icosenyl group, straight or branched heneicosenyl group, straight or branched docosenyl group, straight or branched Each alkenyl group such as a branched tetracosenyl group can be exemplified.

Examples of the alicyclic hydrocarbon group include cycloalkyl groups such as cyclohexyl group and cycloheptyl group; methylcyclopentyl group, dimethylcyclopentyl group (including all structural isomers), and methylethylcyclopentyl group (all ), 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),
Each alkylcycloalkyl group such as a methylethylcycloheptyl group (including all structural isomers) and a diethylcycloheptyl group (including all structural isomers) can be exemplified.

Further, the alkylaryl groups include Ar ¹ , Ar ² , Ar ³ and Ar ^{4 in the} above formula (8).
And the alkylaryl groups having 7 to 18 carbon atoms exemplified in the description.

Specific examples of the diaryl phosphate represented by the general formula (2) include 2-ethylhexyl diphenyl phosphate.

Further, the monoaryl phosphate is represented by the following general formula (10):

Embedded image [Wherein, R ¹⁸ and R ¹⁹ may be the same or different and each represent an aliphatic hydrocarbon group having 1 to 24 carbon atoms or an alicyclic hydrocarbon group having 1 to 24 carbon atoms, and Ar ⁶ is phenyl. X ⁹ , X ¹⁰ , X ¹¹ and X ¹² may be the same or different, and each represents an oxygen atom or a sulfur atom], a naphthyl group or an alkylaryl group having 7 to 18 carbon atoms. Compounds are preferably used.

[0045] Here, examples of the aliphatic hydrocarbon group and the alicyclic hydrocarbon group, exemplified aliphatic hydrocarbon group having 1 to 24 carbon atoms in the description of R ¹⁷ in each of the above formula (9) in And an alicyclic hydrocarbon group having 1 to 24 carbon atoms.

Further, as the alkylaryl group,
The alkylaryl group having 7 to 18 carbon atoms exemplified in the description of Ar ¹ , Ar ² , Ar ³ and Ar ^{4 in} the above formula (8) can be given.

Specific examples of the monoaryl phosphate represented by the above formula (10) include di (2-ethylhexyl) monophenyl phosphate.

The aromatic phosphate used as the component (B) in the present invention is preferably a triaryl phosphate or a diaryl phosphate, and particularly preferably a triaryl phosphate. When such an aromatic phosphate is used, higher oxidation stability and abrasion resistance tend to be obtained.

The content of the component (B) (aromatic phosphate) in the lubricating oil composition of the present invention is not particularly limited, but is preferably 10% by mass or less, more preferably 7% by mass, based on the total amount of the composition. % Or less, more preferably 5% by mass
Or less, most preferably 2% by mass or less. When the content of the component (B) exceeds 10% by mass, it is difficult to obtain a further improvement effect corresponding to the content in various performances, and the storage stability of the lubricating oil composition tends to deteriorate. The content of the component (B) is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and still more preferably 0.05% by mass, based on the total amount of the composition.
Above, most preferably 0.1% by mass or more. (B)
When the content of the component is less than 0.01% by mass, the effect of the addition of the component in the above-described various performances is difficult to be obtained, and the heat / oxidation stability and wear resistance of the lubricating oil composition tend to deteriorate. is there.

The alkyl thiadiazole which is the component (C) in the lubricating oil composition of the present invention has the following general formula (11):

Embedded image [Wherein, R ²⁰ and R ²¹ may be the same or different, each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, a and b may be the same or different, and 0 to 8 1,3,4-thiadiazole represented by the following general formula (12):

Embedded image [Wherein, R ²² and R ²³ may be the same or different, each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, c and d may be the same or different, and 0 to 8 1,2,4-thiadiazole represented by the following general formula (13):

Embedded image [Wherein, R ²⁴ and R ²⁵ may be the same or different, each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, e and f may be the same or different, and 0 to 8 1,4,5-thiadiazole represented by the formula: and mixtures of two or more of the above compounds are preferably used. Specific examples of such a thiadiazole compound include 2,5-bis (n-hexyldithio) -1,3,4-thiadiazole and 2,5-bis (n-octyldithio) -1,3,4-thiadiazole. , 2,5-bis (n-nonyldithio) -1,3,4-
Thiadiazole, 2,5-bis (1,1,3,3-tetramethylbutyldithio) -1,3,4-thiadiazole, 3,5-bis (n-hexyldithio) -1,2,4
-Thiadiazole, 3,5-bis (n-octyldithio) -1,2,4-thiadiazole, 3,5-bis (n
-Nonyldithio) -1,2,4-thiadiazole, 3,
5-bis (1,1,3,3, -tetramethylbutyldithio) -1,2,4-thiadiazole, 4,5-bis (n
-Hexyldithio) -1,2,3-thiadiazole,
4,5-bis (n-octyldithio) -1,2,3-thiadiazole, 4,5-bis (n-nonyldithio)-
1,2,3-thiadiazole, 4,5-bis (1,1,
3,3, -Tetramethylbutyldithio) -1,2,3-
Thiadiazole and mixtures thereof.

The component (C) (alkyl thiadiazole) in the lubricating oil composition of the present invention is not particularly limited, but is preferably 20% by mass or less, more preferably 10% by mass or less, and still more preferably, based on the total amount of the composition. 5% by mass or less,
Most preferably, it is at most 3% by mass. When the content of the component (C) exceeds 20% by mass, it is difficult to obtain a further improvement effect corresponding to the content in various performances, and the storage stability of the lubricating oil composition tends to deteriorate.
The content of the component (C) is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and most preferably 0% by mass or more, based on the total amount of the composition. 0.2 mass% or more. When the content of the component (C) is less than 0.01% by mass, it is difficult to obtain an improvement effect by the addition of the above various performances, and
The seizure resistance and wear resistance of the lubricating oil composition tend to deteriorate.

The component (D) of the present invention is an organic acid salt of at least one metal selected from the group consisting of alkali metals, alkaline earth metals, zinc and lead.

Here, examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include magnesium, calcium, and barium. Of these, alkaline earth metal is preferably used.

Examples of the organic acid salts include, for example, sulfonates, phenates, salicylates,
And mixtures thereof.

The sulfonate has a molecular weight of 10
An alkylaromatic sulfonic acid obtained by sulfonating an alkylaromatic compound of 0 to 1500, preferably 200 to 700, and a base (oxide or hydroxide) of an alkali metal, an alkaline earth metal, zinc or lead
And a neutral sulfonate obtained by reacting the neutral sulfonate with an excess alkali metal, alkaline earth metal, zinc or lead salt or base (oxide, hydroxide, etc.) in the presence of water A basic sulfonate obtained by heating under the following conditions: reacting the neutral sulfonate with an alkali metal, alkaline earth metal, zinc or lead base (oxide or hydroxide) in the presence of carbon dioxide gas Carbonate overbased (ultrabasic) sulfonate obtained by the above method: neutral sulfonate and alkali metal, alkaline earth metal, zinc or lead base (oxide, hydroxide, etc.) or boric acid compound (boric acid) , Boric anhydride, etc.), or the carbonate overbased (ultrabasic) sulfonate, and a boric acid compound (boric acid, boric anhydride, etc.) Borate obtained by reacting the overbased (ultrabasic) sulfonate, and the like and mixtures thereof.

Specific examples of the alkyl aromatic sulfonic acids include so-called petroleum sulfonic acids and synthetic sulfonic acids. Here, as the petroleum sulfonic acid, generally, a sulfonated alkyl aromatic compound of a lubricating oil fraction of a mineral oil, a mahoganic acid by-produced during the production of white oil, and the like are used. Further, as the synthetic sulfonic acid, a by-product in the production process of alkylbenzene as a raw material of a detergent, or obtained by alkylating a polyolefin to benzene, a linear or branched alkylbenzene, or dinonylnaphthalene such as Sulfonated alkyl aromatic compounds such as alkyl naphthalene are used. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, but fuming sulfuric acid or sulfuric anhydride is usually used.

As the phenate, specifically, for example, an alkylphenol having 1 to 2 alkyl groups having 4 to 20 carbon atoms and a base of an alkali metal, an alkaline earth metal, zinc or lead (oxide or Hydroxide) with or without elemental sulfur in the presence or absence of neutral phenate; salt or base of said neutral phenate with excess alkali metal, alkaline earth metal, zinc or lead (Oxides and hydroxides) and a basic phenate obtained by heating in the presence of water; the neutral phenate, an alkali metal, an alkaline earth metal,
A carbonate overbased (ultrabasic) phenate obtained by reacting a zinc or lead base (oxide, hydroxide, etc.) in the presence of carbon dioxide gas; Reaction with alkaline earth metals, zinc or lead bases (oxides, hydroxides) or boric compounds (boric acid, boric anhydride, etc.), or with the carbonate overbased (ultrabasic) phenates Examples include borate overbased (ultrabasic) phenates obtained by reaction with a boric acid compound (boric acid, boric anhydride, etc.), and mixtures thereof.

Further, as the salicylate, specifically, for example, an alkylsalicylic acid having 1 to 2 alkyl groups having 4 to 20 carbon atoms and a base (oxide) of alkali metal, alkaline earth metal, zinc or lead And hydroxide)
And a neutral salicylate obtained by reacting with an elemental sulfur in the presence or absence of elemental sulfur; said neutral salicylate and an excess alkali metal, alkaline earth metal, zinc or lead salt or base (oxide, Hydroxides) and basic salicylates obtained by heating in the presence of water; neutral salicylates and bases of alkali metals, alkaline earth metals, zinc or lead (oxides, hydroxides, etc.) And a carbonate overbased (ultrabasic) salicylate obtained by reacting the neutral salicylate with a base of an alkali metal, an alkaline earth metal, zinc or lead (oxide, Reaction with a boric acid compound (such as boric acid or boric anhydride), or boric acid with an overbased (ultrabasic) metal salicylate carbonate Things (boric acid, etc. boric anhydride)
And overbased (ultrabasic) salicylates obtained by the reaction with, and mixtures thereof.

As the component (D) in the present invention, one kind selected from the above compounds may be used alone, or a mixture of two or more kinds may be used.

The total base number of the component (D) of the present invention is not particularly limited, but is preferably from 0 to 500 mgKOH / g, more preferably from 0 to 450 mgKOH / g. The total base number referred to here is JIS K250
1-1992 "Petroleum products and lubricating oils-Neutralization test method"
Means the total base number measured by the hydrochloric acid method according to

Further, the content of the component (D) in the lubricating oil composition of the present invention is not particularly limited, but is preferably 20% by mass or less, more preferably 10% by mass, based on the total amount of the composition.
% By mass, more preferably 5% by mass or less, most preferably 3% by mass or less. When the content of the component (D) is 20
If the amount is more than 100% by mass, it is difficult to obtain a further improvement effect corresponding to the content in various performances, and the storage stability of the lubricating oil composition tends to deteriorate. Also,
The content of the component (D) is preferably at least 0.01% by mass, more preferably at least 0.05% by mass, still more preferably at least 0.1% by mass, and most preferably at least 0.2% by mass, based on the total amount of the composition. % By mass or more. When the content of the component (D) is 0.
When the content is less than 01% by mass, it is difficult to obtain the effect of the addition of the various performances described above, and when used as a lubricating oil composition for a sliding guide surface, the water-soluble cutting fluid separation property and the stick-slip resistance are poor. It tends to worsen.

The lubricating oil composition of the present invention is obtained by blending the above base oil with four components (A) to (D).
In order to further enhance its excellent properties, it can be used in a form containing other various additives as necessary.
Examples of such additives include oiliness improvers such as oleic acid, esters and fats and oils, metal deactivators such as benzotriazole; ashless dispersants such as silicone oil and succinimide; and defoaming agents such as fluorosilicone oil. Demulsifiers such as condensation products of ethylene oxide and propylene oxide; Pour point depressants such as polymethacrylate;
Viscosity index improvers such as polymethacrylate, polybutene, polyalkylstyrene, olefin copolymer, styrene-diene copolymer, styrene-maleic anhydride copolymer, and the like. One of these additives may be used alone, or two or more thereof may be used in combination. Further, the amount of these additives is not particularly limited, but the total amount of the additives is preferably 15% by mass or less based on the total amount of the composition.

As described above, the lubricating oil composition of the present invention, which has excellent heat / oxidation stability and high seizure resistance and abrasion resistance, is suitable as an industrial circulating system oil such as a hydraulic oil or a gear oil. Used for It is also suitably used in applications such as sliding surface oil for machine tools, bearings, and lubricating oil for compressors and the like.

[0064]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Examples 1 to 8 and Comparative Examples 1 to 6 The lubricating oils of Examples 1 to 8 were prepared using the base oils shown below and the components (A) to (D) so that the compositions shown in Table 1 below were obtained. Each composition was prepared. Also, as a comparative composition,
The lubricating oil compositions of Comparative Examples 1 to 4 which do not contain any one of the components (A) to (D), and the components (A) to (C), and instead of the component (D) The lubricating oil compositions of Comparative Examples 5 and 6 containing the component (E) (boric acid-containing polybutenyl succinimide) were prepared to have the compositions shown in Table 2, respectively.

Base oil base 1: paraffinic solvent refined mineral oil [Kinematic viscosity: 68 mm 2
/ S (@ 40 ° C.)] Group 2: poly-alpha-olefin [number average molecular weight: 6
32], and 7: 3 (by volume) of the polyol ester
Mixed oil [Kinematic viscosity of mixed oil: 68 mm2 / s (# 40
C)]] (A) Component A1: 2,6-Di-tert-butyl-paracresol A2: 2,4,6-Tri-tert-butyl-phenol (B) Component B1: Tricresyl Phosphate B2: Monocresyl diphenyl phosphate (C) component C1: 2,5-bis (n-nonyldithio) -1,3,4
-Thiadiazole C2: 2,5-bis (1,1,3,3
-Tetramethyldithio) -1,3,4-thiadiazole (D) component D1: calcium sulfonate [weight average molecular weight 450
Calcium salt of petroleum sulfonic acid, total base number (perchloric acid method): 0 mgKOH / g, calcium content: 2.0% by mass] D2: magnesium sulfonate [weight average molecular weight 45]
Petroleum sulfonic acid calcium salt of 0, total base number (perchloric acid method): 3 mg KOH / g, magnesium content: 1.
D3: calcium carbonate-containing overbased calcium phenate [overbased calcium salt of alkylphenol having an alkyl group derived from an α-olefin mixture having 9 to 18 carbon atoms, total base number (perchloric acid method) ): 125 mgK
OH / g, calcium content: 5.7% by mass] D4: Overbased calcium salicylate containing calcium carbonate [overbased of alkyl salicylic acid having an alkyl group derived from an α-olefin mixture having 12 to 20 carbon atoms] Calcium salt, total base number (perchloric acid method): 160m
gKOH / g, calcium content: 6.2% by mass] (E) component E1: boric acid-containing polybutenyl succinimide [bis-type, weight average molecular weight of polybutenyl group: 1,000;
Nitrogen content: 2.0%] E2: boric acid-containing polybutenyl succinimide [monotype, weight average molecular weight of polybutenyl group: 1,000;
Nitrogen content: 3.8%].

Next, each of the lubricating oil compositions of Examples 1 to 8 and Comparative Examples 1 to 6 was used as a sample oil, and its solubility, friction characteristics and wear resistance were evaluated by the following test methods. did. The results are shown in Tables 1 and 2.

[Evaluation Test Method] Oxidation stability: Turbine oil oxidation stability test (TOST)
A turbine oil oxidation stability test was performed for each sample oil in accordance with the “lubricating oil thermal stability test method” specified in IS K 2540, and the oxidation stability was evaluated. The oxidation stability in each test was evaluated by measuring the increase in the total acid value of each composition 1000 hours after the start of the test.

Thermal stability: Thermal stability test A sample oil was placed in a 50 ml beaker according to the “Lubricant Thermal Stability Test Method” defined in JIS K 2540.
5 g, and put copper and iron catalyst in it,
And the amount of sludge in the sample oil after 12 days was measured.

The copper and iron catalysts used were each obtained by cutting a catalyst used for a turbine oil oxidation stability test (JIS K 2514) into eight turns (about 3.5 cm in length).

Seizure resistance: Shell 4 ball test ASTM D 2783-88 "Standard T"
est Methodfor Measurement
of Extreme-PressurePrope
rties of Lubricating Flui
ds (Four-Ball Method) ", a four-shell test was performed to evaluate the seizure resistance of each sample oil.
It was performed at 0 rpm. In evaluating the seizure resistance, L
oad Wear Index (WLI) was used.

Abrasion resistance: FALEX abrasion test The FLEX abrasion test was performed according to ASTM D 3233-93.
“StandardTest Methods for
Measurement of Extreme P
resource Properties of Flu
id Lubricants (Falex Pin
Vee Block Methods), which was modified to measure the amount of wear. The pin (journal) had an outer diameter of 6.35 mm (1 mm).
/ 4 inch) and steel having a length of 31.75 mm (1.1 / 4 inch), and a V-shaped block made of steel having an angle of 96 degrees. The test conditions were as follows: rotation speed 1500 rpm, Dir
ect Load was 100 lbs, and the test time was 20 hours.

[0073]

[Table 1]

[0074]

[Table 2]

As shown in Table 1, it was confirmed that all of the lubricating oil compositions of Examples 1 to 8 had excellent thermal and oxidative stability and sufficiently high friction characteristics and abrasion resistance. Was. On the other hand, the lubricating oil compositions of Comparative Examples 1 to 6 are shown in Table 2
As shown in Table 2, the results showed that one of the thermal / oxidative stability, seizure resistance and abrasion resistance was insufficient.

[0076]

As described above, according to the present invention, it has high heat and oxidation stability, excellent abrasion resistance and seizure resistance, and is suitable for industrial circulating system oils such as hydraulic oils and gear oils. Thus, even when used under high temperature conditions, a lubricating oil composition capable of suppressing seizure of a mechanical sliding portion and generation of sludge for a long period of time can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int. Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C10M 137/04 C10M 137/04 139/00 139/00 A 159/22 159/22 159/24 159/24 // C10N 10:02 C10N 10:02 10:04 10:04 10:08 10:08 30:06 30:06 30:08 30:08 30:10 30:10 40:04 40:04 40:08 40 : 08 F term (reference) 4H104 BB05C BB24C BB35C BG13C BG19C BH03C CJ15C DA02A DB06C DB07C EB02 FA01 FA02 FA04 LA03 LA04 LA05 PA02 PA05

Claims (1)

[Claims] 1. A base oil comprising at least one selected from the group consisting of mineral oils, fats and oils, and synthetic oils, comprising the following compound (A)
-(D): (A) alkylphenol, (B) aromatic phosphate, (C) alkyl thiadiazole, and (D) at least one selected from the group consisting of alkali metals, alkaline earth metals, zinc and lead. A lubricating oil composition comprising an organic acid salt of a metal.