JP2020090557A - Lubricant composition - Google Patents

Abstract

To provide a lubricant composition which is reduced in viscosity, has excellent storage stability and low friction and further to provide a lubricant composition improved in wear resistance and scoring resistance.SOLUTION: There is provided a lubricant composition which comprises (A) a lubricant base oil, (B) a phosphorus-based extreme-pressure agent, (D) an ashless dispersant and (E) a copolymer having a weight average molecular weight of 5000 to 100000 which has (E1) a unit derived from an alkyl (meth)acrylate having an alkyl group having 1 to 30 carbon atoms and (E2) a unit derived from a hydroxyl group-containing (meth)acrylate represented by a specific structural formula and has a repeating unit derived from the component (E1) and a repeating unit derived from the component (E2) in the mass ratio of (E1):(E2)=95 to 60:5 to 40, wherein the lubricant composition has a kinematic viscosity at 100°C of 2 to 10 mm/s and contains a boron content of less than 50 ppm or contains no boron.SELECTED DRAWING: None

Description

The present invention relates to a lubricating oil composition, particularly a lubricating oil composition applicable to automobiles. More specifically, the present invention relates to a lubricating oil composition suitable for an automobile transmission, a lubricating oil composition suitable for an automobile gear oil, and a lubricating oil composition suitable for a hybrid vehicle.

Lubricating oil compositions are used for various purposes such as automobiles and machines. In recent years, reduction in viscosity of lubricating oil compositions for automobiles has been demanded from the viewpoint of fuel saving. However, lowering the viscosity of the lubricating oil composition affects the oil film forming ability. The low viscosity is originally intended to realize fuel efficiency, but even if the viscosity of the conventional lubricating oil composition is reduced as it is, the oil film forming ability is inferior, resulting in higher friction. Depending on the situation, fuel saving may not be realized. Further, when the oil film forming ability is lowered due to the lowering of viscosity, direct contact between the metals occurs, resulting in insufficient lubrication, resulting in severe wear, and thus the function as a lubricating oil composition. It will not fully fulfill.

Patent Document 1 describes a lubricating oil composition that is preferably used as a gear oil for automobiles, including a base oil, a viscosity index improver, a molybdenum-based friction modifier, a boron-containing dispersant, and a sulfur-based extreme pressure. Agent, a phosphorus-based extreme pressure agent, and a sulfur-phosphorus-based extreme pressure agent, at least two kinds of extreme pressure agents, or a lubricating oil composition containing a sulfur-phosphorus-based extreme pressure agent is described. Patent Document 1 describes that the lubricating oil composition has both fuel economy and extreme pressure properties, and further has shear stability, oxidation stability, and abrasion resistance.

Patent Document 2 describes a lubricating oil composition suitable as a gear oil for automobiles, especially a differential gear oil. It is described that a lubricating oil composition containing a specific sulfur-based extreme pressure agent can suppress bearing wear and scoring on the gear tooth surface even if the viscosity is reduced. Patent Literature 3 discloses a lubricating oil composition having excellent wear resistance and seizure resistance by using a molybdenum-based friction modifier and an extreme pressure agent containing sulfur as a final reduction gear lubricating oil composition. Is listed. Patent Document 4 describes a gear oil lubricating oil composition obtained by adding a molybdenum-based friction modifier and a sulfur-based extreme pressure agent to an ester-based base oil.

JP, 2016-190897, A JP, 2017-132875, A WO2016/136873 WO2015/056784

However, in any of the above-mentioned patent documents, in addition to the fuel economy associated with the reduction in viscosity, while ensuring storage stability, further compatibility of low wear and good scoring characteristics must be disclosed as an issue. There is no suggestion. Therefore, the present inventors have an object to provide a lubricating oil composition having excellent storage stability and low friction while having a low viscosity. Furthermore, the present invention provides a lubricating oil composition having the above-mentioned properties, but also improved wear resistance and scoring resistance.

In order to solve the above-mentioned problems, the present inventors have added a polymer-based friction to a lubricating oil composition containing a lubricating base oil, a phosphorus-based extreme pressure agent, a sulfur-based extreme pressure agent, and a boron-containing ashless dispersant. When a copolymer having a repeating unit derived from an alkyl (meth)acrylate and a hydroxyl group-containing acrylate is added as a regulator, the problem that the lubricating oil composition gels and the copolymer becomes a lubricating oil composition There was the problem of precipitation instead of dissolution.

Therefore, the present inventor has conducted further diligent studies, and a lubricating oil composition containing no specific amount of boron or more is derived from an alkyl (meth)acrylate and a hydroxyl group-containing (meth)acrylate as a polymer-based friction modifier. The lubricating oil composition does not gel even when a copolymer having a repeating unit is blended, the copolymer does not precipitate, has a low viscosity, and has excellent storage stability and low friction. It has been found that a lubricating oil composition can be provided. Further, the above-mentioned polymer-based friction modifier has a specific weight average molecular weight and a specific amount of repeating units derived from a hydroxyl group-containing (meth)acrylate, whereby the friction coefficient can be effectively reduced. The inventors have found that they can do so and have completed the present invention.

That is, the present invention is a lubricating oil composition containing the following components (A) to (E), which is (A) a lubricating base oil,
(B) phosphorus-based extreme pressure agent,
(C) Sulfur-based extreme pressure agent,
(D) an ashless dispersant, and (E) a unit derived from the following component (E1) and a unit derived from the following component (E2), having a weight average molecular weight of 5,000 to 100,000, Copolymer (E1) carbon number having a repeating unit derived from the following (E1) component and a repeating unit derived from the following (E2) component in a mass ratio of (E1):(E2)=95:5 to 50:50 having 1 to 30 alkyl group, the alkyl (meth) acrylate (E2) the following formula (1) or (2) a hydroxyl group-containing represented by (meth) acrylate _{CH 2 = C (a 1)} -COOR 1 -OH (1)
_{CH 2 = C (A 2)} -COOR 2 -O- [C (= O) -R 3 O] n -H (2)
(In the formula, R ₁ is an alkylene group having 1 to 30 carbon atoms, R ₂ is an alkylene group having 1 to 30 carbon atoms, R ₃ is an alkylene group having 1 to 8 carbon atoms, and A ₁ and A ₂ is a methyl group or a hydrogen atom, and n is an integer of 1 to 25)
The lubricating oil composition has a kinematic viscosity at 100° C. of ^{2 to} 10 mm ² /s, and
The above-mentioned lubricating oil composition is characterized in that the content of boron in the lubricating oil composition is less than 50 ppm or does not contain boron.

Preferred embodiments of the present invention are as follows.
(1) The copolymer (E) further has (E3) a unit derived from an amino group-containing (meth)acrylate represented by the following formula (3) or (4).
_{CH 2 = C (A 1)} -COOR 1 -N (B 1) (B 2) (3)
_{CH 2 = C (A 2)} -COOR 2 -O- [C (= O) -R 3 NH] n -H (4)
(In the formula, R ₁ is an alkylene group having 1 to 30 carbon atoms, R ₂ is an alkylene group having 1 to 30 carbon atoms, R ₃ is an alkylene group having 1 to 10 carbon atoms, and A ₁ and A ₂ are each a methyl group or a hydrogen atom, _{B 1} and _{B 2,} independently of one another, a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, n is an integer from 1 to 25).
(2) The copolymer (E) contains a repeating unit derived from the component (E1), a repeating unit derived from the component (E2), and a repeating unit derived from the component (E3), which are (E1):(E2):( E3) = 90 to 50:5 to 45:5 to 20 in a mass ratio (the sum of the three ratios is 100).
(3) The component (E1) is a combination of the following component (E1-1) and the following component (E1-2). (E1-1) An alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms. (E1-2) An alkyl (meth)acrylate having an alkyl group having 9 to 30 carbon atoms.
(4) As the (B) phosphorus-based extreme pressure agent,
(B1) an amine salt of a phosphoric acid ester having an alkyl group having 4 to 30 carbon atoms, or
(B2) contains any one or more thiophosphate ester amine salts.

Furthermore, the lubricating oil composition of the present invention contains an acidic phosphoric acid ester having a short-chain alkyl group having a small number of carbon atoms, and further contains a phosphorous acid ester or a phosphonic acid ester, thereby achieving the above effects. In addition, a lubricating oil composition having excellent wear resistance and scoring resistance is provided.

(5) The (B) phosphorus-based extreme pressure agent further comprises one or two (B3) alkyl groups, each of which has 4 to 10 carbon atoms and further comprises an acidic phosphoric acid ester.
(6) The phosphorus-based extreme pressure agent (B) further includes at least one selected from (B4) phosphite ester and (B5) phosphonate ester.
(7) The sulfur-based extreme pressure agent (C) comprises at least one selected from sulfurized olefins, sulfurized fats and oils, sulfurized esters, polysulfides, and thiadiazole.
(8) The sulfur-based extreme pressure agent (C) is characterized in that the amount of active sulfur is 0.5 to 30% by mass.
(9) The ashless dispersant (D) has a boron content of less than 0.3% by mass. (10) The ashless dispersant (D) has no boron.
(11) Further, it is characterized by including a friction modifier (F) containing molybdenum.
(12) The (F) molybdenum friction modifier is at least one selected from molybdenum dithiocarbamate (MoDTC) and molybdenum dithiophosphate (MoDTP).
(13) The sulfur content in the lubricating oil composition is 0.3 to 5% by mass.
(14) The phosphorus content in the lubricating oil composition is 200 to 2000 ppm.
(15) The molybdenum content in the lubricating oil composition is 100 to 1500 ppm.
(16) The lubricating oil composition is used in a hybrid vehicle.
(17) The lubricating oil composition is used for a transmission fluid.
(18) The lubricating oil composition is used for gear oil.

The lubricating oil composition of the present invention has excellent storage stability and low friction while having low viscosity. Further, the present invention can provide a lubricating oil composition having the antiwear property required for gear oils and the excellent scoring resistance. The lubricating oil composition of the present invention can be suitably used particularly for hybrid vehicles, transmissions, and gear oils.

(A) Lubricating oil base oil The lubricating oil base oil in the present invention is not particularly limited, and conventionally known lubricating oil base oil can be used. Lubricating base oils include mineral base oils, synthetic base oils, and mixed base oils thereof.

The method for producing the mineral base oil is not limited. Mineral oil base oils are highly refined paraffinic mineral oils (high viscosity index mineral oil base oils) obtained by subjecting hydrorefined oils, catalytic isomerized oils, etc. to solvent dewaxing or hydrodewaxing. ) Is preferred. Further, as mineral oil-based base oils other than the above, for example, a lubricating oil raw material, phenol, raffinate obtained by solvent refining using an aromatic extraction solvent such as furfural, silica-alumina as a carrier cobalt, hydrogen such as molybdenum. Examples thereof include hydrotreated oil obtained by hydrotreatment using a hydrotreatment catalyst. For example, 100 neutral oil, 150 neutral oil, 500 neutral oil, etc. can be mentioned.

Examples of synthetic base oils include base oils obtained by hydrocracking and hydroisomerizing a raw material such as wax obtained by Fischer-Tropsch synthesis from natural gas such as methane (so-called Fischer-Tropsch derived oil). Base oil), poly-α-olefin base oil, polybutene, alkylbenzene, polyol ester, polyglycol ester, dibasic acid ester, phosphoric acid ester, and silicone oil. The poly-α-olefin (PAO) base oil is not particularly limited, but for example, 1-octene oligomer, 1-decene oligomer, ethylene-propylene oligomer, isobutene oligomer and hydrides thereof can be used.

The lubricating base oil may be used alone or in combination of two or more. When two or more types of lubricating base oils are used in combination, they may be mineral base oils, synthetic base oils, or a combination of mineral oil bases and synthetic base oils, and the embodiment is not limited.

The kinematic viscosity of the lubricating base oil is not limited as long as it does not impair the gist of the present invention. Particularly, in order to obtain a lubricating oil composition having a low viscosity, it is preferable that the entire lubricating base oil has a kinematic viscosity 1 to 9mm ² / s at 100 ° C., more preferably from 1 to 8 mm ² / s, more It is preferable to have ² to 6 mm ² /s. If the kinematic viscosity of the lubricating base oil at 100° C. exceeds the above upper limit, it may be difficult to reduce the viscosity of the lubricating oil composition, and it may be difficult to achieve fuel economy. If the kinematic viscosity at 100°C is less than the lower limit value described above, fuel economy can be achieved, but the wear characteristics may be adversely affected.

(B) Phosphorus Extreme Pressure Agent The lubricating oil composition of the present invention has a phosphorus extreme pressure agent, but the type thereof is not limited. In addition, the phosphorus-based extreme pressure agent in the present invention includes both an extreme pressure agent containing no sulfur and containing phosphorus, and an extreme pressure agent containing sulfur and phosphorus.
A preferred first embodiment of the present invention is a lubricating oil composition containing (B1) an amine salt of a phosphoric acid ester having an alkyl group having 4 to 30 carbon atoms or (B2) a thiophosphoric acid ester amine salt.
Moreover, as a preferable 2nd aspect of this invention, the lubricating oil composition containing the acidic phosphoric acid ester which has 1 or 2 (B3) alkyl groups, and all these alkyl groups have carbon numbers 4-10. It is a thing.
Furthermore, a preferred third aspect of the present invention is a lubricating oil composition containing at least one selected from (B4) phosphite ester and (B5) phosphonate ester.
Although it may have the requirements of the first aspect, the second aspect, and the third aspect alone, or may satisfy the requirements of two or more, preferably, the first aspect, the second aspect, and the A lubricating oil composition that satisfies two or more, more preferably all of the three aspects is preferable. Particularly preferably, by containing a phosphorus-based extreme pressure agent satisfying the requirements of the second aspect and the third aspect, it is possible to reduce wear of the lubricating oil composition having a low viscosity and improve scoring resistance. You can

The content of the component (B) in the lubricating oil composition is not particularly limited, but the phosphorus atom content is preferably 200 to 2000 mass ppm, more preferably 300 to 1700 mass ppm, and 300 to 1500 mass ppm. Is more preferable. If the content exceeds the above upper limit, sludge may be generated, which is not preferable. When the content is less than the lower limit value described above, friction is likely to be high, which may not contribute to fuel saving, which is not preferable. When two or more phosphorus-based extreme pressure agents are used in combination, they may be added so that the total phosphorus atom content satisfies the above range.

(B1) Amine salt of phosphoric acid ester having an alkyl group having 4 to 30 carbon atoms The amine salt of phosphoric acid ester having an alkyl group having 4 to 30 carbon atoms is (R ¹ O) _b P(═O)(OH _{^{) 3-b · (NH c}} R 2 O 3-c) represented by _3-b. It may be a mixture of compounds in which b and c are 1 or 2 in the above formula and b and c have different values. In the above formula, R ¹ and R ² are each independently a hydrocarbon group having 4 to 30 carbon atoms. The hydrocarbon group may be linear or branched. As the component (B1), one type of amine salt of an acidic phosphoric acid ester having the above alkyl group may be used alone, or two or more types may be used in combination. R ¹ and R ² are each independently an alkyl group having 4 to 30 carbon atoms, preferably an alkyl group having 4 to 20 carbon atoms, and more preferably an alkyl group having 4 to 16 carbon atoms.

The amount of the amine salt of a phosphoric acid ester contained in the lubricating oil composition of the present invention is not particularly limited, but the phosphorus atom content is preferably 100 to 1500 mass ppm with respect to the total mass of the lubricating oil composition, 180-1200 mass ppm is more preferable, and 200-1000 mass ppm is still more preferable. If the content exceeds the above upper limit, sludge may be generated, which is not preferable. If the content is less than the above lower limit, wear is likely to increase, which is not preferable. When two or more kinds of amine salts of phosphoric acid esters are used in combination, they may be added so that the total phosphorus atom content satisfies the above range.

(B2) The amine salt of thiophosphoric acid ester amine salt thiophosphoric acid ^esters, table with _{(R 3 O) d P (} = X) (XH) 3-d · (NH e R 4 O 3-e) 3-d To be done. In the above formula, d,e=1 or 2, and d and e may be used as a mixture of compounds having different values. X is an oxygen atom or a sulfur atom, but at least one is an oxygen atom. In the above formula, R ³ and R ⁴ are independently of each other an alkyl group having 4 to 30 carbon atoms. As long as it is an alkyl group having 4 to 30 carbon atoms, it may be linear or branched. As the component (B2), one type of the thiophosphate ester amine salt may be used alone, or two or more types may be used in combination. Although the carbon number of R ³ and R ⁴ is not limited, it is preferably within the range of 4 to 30 carbon atoms, more preferably within the range of 4 to 20 carbon atoms, and even more preferably within the range of 4 to 16 carbon atoms.

The amount of the amine salt of thiophosphoric acid ester contained in the lubricating oil composition of the present invention is not particularly limited, but is 100 to 1500 mass ppm as a phosphorus atom content with respect to the mass of the entire lubricating oil composition. Is preferred, 180 to 1200 mass ppm is more preferred, and 200 to 1000 mass ppm is even more preferred. If the content exceeds the above upper limit, sludge may be generated, which is not preferable. If the content is less than the above lower limit, wear is likely to increase, which is not preferable. When two or more amine salts of thiophosphoric acid esters are used in combination, they may be added so that the total phosphorus atom content satisfies the above range.

The lubricating oil composition of the present invention preferably has either the component (B1) or the component (B2) described above as a preferred first aspect, and more preferably has both the component (B1) and the component (B2).

(B3) has one or two alkyl groups, and each of the alkyl groups has one or two acidic phosphate (B3) alkyl groups having 4 to 10 carbon atoms , and the alkyl group is all have 4 to 10 carbon atoms, and acidic phosphoric acid ^ester, represented by _{(R 5 O) a P (} = O) (OH) 3-a. It can also be used as a mixture of compounds in which a=1 or 2 in the above formula and a is a different value. In the above formula, R ^1's each independently represent an alkyl group having 4 to 10 carbon atoms. Of the alkyl groups having 4 to 10 carbon atoms, a butyl group, a pentyl group, a hexyl group, and an octyl group are preferable, and they may have a branch. As the component (B), one type of acidic phosphoric acid ester having an alkyl group may be used alone, or two or more types may be used in combination. The smaller the carbon number of R ^5, the more preferable. In particular, an acidic phosphoric acid ester having an alkyl group having 4 carbon atoms is preferable because it is more excellent in the effect of reducing the friction coefficient.

The acidic phosphoric acid ester preferably includes acidic phosphoric acid (di)butyl ester, acidic phosphoric acid (di)pentyl ester, acidic phosphoric acid (di)hexyl ester, and acidic phosphoric acid (di)octyl ester. .. More preferred is acidic phosphoric acid (di)butyl ester or acidic phosphoric acid (di)hexyl ester, and most preferred is acidic phosphoric acid (di)butyl ester.

The amount of the acidic phosphoric acid ester contained in the lubricating oil composition of the present invention is not particularly limited, but is 100 to 1500 mass ppm as a phosphorus atom content with respect to the mass of the entire lubricating oil composition. 180-1200 mass ppm is more preferable, and 200-1000 mass ppm is still more preferable. If the content exceeds the above upper limit, sludge may be generated, which is not preferable. When the content is less than the lower limit value described above, friction is likely to be high, which may not contribute to fuel saving, which is not preferable. When two or more types of acidic phosphoric acid esters are used in combination, they may be added so that the total phosphorus atom content satisfies the above range.

Further, the lubricating oil composition of the present invention preferably contains a phosphorus-based extreme pressure agent composed of at least one selected from (B4) phosphite ester and (B5) phosphonate ester. By including the component (B4) or the component (B5), the wear of the lubricating oil composition can be further reduced. Preferably, at least one selected from the above-mentioned (B1) component and (B2) component, and at least one selected from the above-mentioned (B3) component and/or the following (B4) component and (B5) component A lubricating oil composition comprising a seed. Most preferably, a lubricating oil containing at least one selected from the above-mentioned (B1) component and (B2) component, the above-mentioned (B3) component, and at least one selected from the following (B4) component and (B5) component It is a composition.

(B4) phosphite ester (B4) phosphite ester is, for example, a compound represented by the following formula (1) or (2).
_{^{(R 6 O) b P (}} = O) (OH) 2-b H (1)
(R ⁷ O) ₃ P (2)
In the above formula (1), b=1 or 2, and R ^6's independently of each other are hydrocarbon groups. In the above formula (2), R ^7's each independently represent a hydrocarbon group. The number of carbon atoms of R ⁶ and R ⁷ is not particularly limited.

In the above formula (1), R ⁶ is preferably an alkyl group having 4 to 30 carbon atoms, more preferably an alkyl group having 4 to 20 carbon atoms, further preferably an alkyl group having 4 to 12 carbon atoms, and most preferably Is preferably an alkyl group having 4 to 8 carbon atoms. In the above formula (2), R ⁷ is preferably an alkyl group having 4 to 30 carbon atoms, more preferably an alkyl group having 4 to 20 carbon atoms, further preferably an alkyl group having 4 to 12 carbon atoms, and most preferably It is an alkyl group having 4 to 8 carbon atoms.

As the phosphite, for example, tributyl phosphite, dibutyl phosphite, monobutyl phosphite, tripentyl phosphite, dipentyl phosphite, monopentyl phosphite, phosphite Phosphoric acid trihexyl ester, phosphorous acid dihexyl ester, phosphorous acid monohexyl ester, phosphorous acid triheptyl ester, phosphorous acid diheptyl ester, phosphorous acid monoheptyl ester, phosphorous acid trioctyl ester, phosphorous acid Dioctyl ester, and phosphorous acid monooctyl ester are mentioned. Among them, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, and trioctyl phosphite are preferably used.

(B5) Phosphonic acid ester (B5) Phosphonic acid ester is represented by the following formula.
(R ⁸ O)(R ⁹ O)(R ¹⁰ )P(=O) (3)
In formula (3), R ⁸ and R ⁹ are each independently a hydrogen atom or a monovalent hydrocarbon group, at least one of R ⁸ and R ⁹ is a monovalent hydrocarbon group, and R ¹⁰ is a monovalent hydrocarbon group. It is a hydrocarbon group.

In the above formula (3), R ⁸ and R ⁹ are each independently a hydrogen atom or preferably a monovalent hydrocarbon group having 1 to 30 carbon atoms, at least one of which is a hydrocarbon group. That is, one of R ⁸ and R ⁹ is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 2 to 20 carbon atoms, and an alkyl group having 4 to 18 carbon atoms. Is more preferable, and an alkyl group having 8 to 18 carbon atoms is most preferable.

In the above formula (3), R ¹⁰ is preferably a monovalent hydrocarbon group having 1 to 30 carbon atoms, more preferably an alkyl group, still more preferably an alkyl group having 2 to 20 carbon atoms, and most preferably Is an alkyl group having 4 to 18 carbon atoms, and particularly an alkyl group having 8 or 18 carbon atoms.

Examples of the phosphonate ester include dimethyl butyl phosphonate, diethyl butyl phosphonate, dipropyl butyl phosphonate, dibutyl butyl phosphonate, dipentyl butyl phosphonate, dihexyl butyl phosphonate, diheptyl butyl phosphonate, dioctyl butyl phosphonate, hexyl phosphonate. Dimethyl acid, hexylphosphonic acid diethyl, hexylphosphonic acid dipropyl, hexylphosphonic acid dibutyl, hexylphosphonic acid dipentyl, hexylphosphonic acid dihexyl, hexylphosphonic acid diheptyl, hexylphosphonic acid dioctyl, octylphosphonic acid dimethyl, octylphosphonic acid diethyl, octylphosphonic acid Acid dipropyl, octylphosphonate dibutyl, octylphosphonate dipentyl, octylphosphonate dihexyl, octylphosphonate diheptyl, octylphosphonate dioctyl, decylphosphonate dimethyl, decylphosphonate diethyl, decylphosphonate dipropyl, decylphosphonate dibutyl, decylphosphone Acid dihexyl, didecylphosphonate dioctyl, decylphosphonate didecyl, dodecylphosphonate dimethyl, dodecylphosphonate diethyl, dodecylphosphonate dipropyl, dodecylphosphonate dibutyl, dodecylphosphonate dihexyl, dodecylphosphonate dioctyl, dodecylphosphonate didecyl, dodecylphosphone Acid dodecyl, dimethyl tetradecylphosphonate, diethyl tetradecylphosphonate, dipropyl tetradecylphosphonate, dibutyl tetradecylphosphonate, dihexyl tetradecylphosphonate, dioctyl tetradecylphosphonate, didecyl tetradecylphosphonate, didodecyl tetradecylphosphonate Ditetradecylphosphoric acid phosphonate, dimethyl hexadecylphosphonic acid, diethyl hexadecylphosphonic acid, dipropyl hexadecylphosphonic acid, dibutyl hexadecylphosphonic acid, dihexyl hexadecylphosphonic acid, dioctyl hexadecylphosphonic acid, didecyl hexadecylphosphonic acid, hexa Didecylphosphonic acid didodecyl, hexadecylphosphonic acid ditetradecyl, octadecylphosphonic acid dimethyl, octadecylphosphonic acid diethyl, octadecylphosphonic acid dipropyl, octadecylphosphonic acid dibutyl, octadecylphosphonic acid dipentyl, octadecylphosphonic acid dihexyl, octadecylphosphonic acid diheptyl, octadecylphosphonic acid Examples include dioctyl and dioctadecyl octadecylphosphonate.

(C) Sulfur-based extreme pressure agent The lubricating oil composition of the present invention contains a sulfur-based extreme pressure agent. The sulfur-based extreme pressure agent imparts seizure resistance and can suitably function as a lubricating oil composition for gear oils. The component (C) can be selected from known sulfur-based extreme pressure agents. At least one selected from sulfurized olefins, sulfurized fats and oils, sulfurized esters, polysulfides and thiadiazoles is preferable, and sulfurized olefins, sulfurized fats and oils and sulfurized esters are particularly preferable. In the present invention, the component (C) does not include an extreme pressure agent containing phosphorus.

The sulfurized olefin and polysulfide are represented by the following general formula (4). As will be described later, sulfurized olefins are obtained by sulfurizing olefins, and polysulfides are obtained by sulfurizing hydrocarbon raw materials other than olefins.
^{_{R 11 -S x - (R 12}} -S x -) n -R 13 (4)

In the above formula (4), R ¹¹ and R ¹³ are, independently of each other, a monovalent hydrocarbon group, for example, a saturated or unsaturated aliphatic group having a straight chain structure or a branched chain having 2 to 20 carbon atoms. Examples thereof include a hydrocarbon group and an aromatic hydrocarbon group having 2 to 26 carbon atoms. More specifically, there are an ethyl group, a propyl group, a butyl group, a nonyl group, a dodecyl group, a propenyl group, a butenyl group, a benzyl group, a phenyl group, a tolyl group, a hexylphenyl group and the like.

In the above formula (4), R ¹² is a saturated or unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms and having a linear structure or a branched chain, and an aromatic hydrocarbon group having 6 to 26 carbon atoms. Etc. can be mentioned. More specifically, an ethylene group, a propylene group, a butylene group, a phenylene group and the like can be mentioned.

In the above formula (4), x is independently an integer of 1 or more, and preferably an integer of 1 to 8. If x is small, extreme pressure properties will be small, and if x is too large, thermal oxidation stability will tend to be reduced. In order to obtain both extreme pressure property and thermal oxidative stability, x in the unit shown in parentheses is preferably an integer of 1 to 6, more preferably an integer of 2 to 4, particularly preferably 2 or It is 3.

Examples of sulfurized olefins include those obtained by sulfurizing olefins such as polyisobutylene and terpenes with sulfur and other sulfurizing agents.

Examples of the polysulfide compound include diisobutyl disulfide, dioctyl polysulfide, di-tert-butyl polysulfide, and di-tert-benzyl polysulfide.

Sulfurized fats and oils are reaction products of fats and sulfur and are obtained by sulfidation reaction of animal and vegetable fats and oils such as lard, beef tallow, whale oil, palm oil, coconut oil and rapeseed oil. .. This reaction product is not a single substance but a mixture of various substances, and the chemical structure itself is not clear.

The sulfurized ester is obtained by sulfurizing a fatty acid ester obtained by the reaction of the above-mentioned fat and oil with various alcohols. Like sulfurized fats and oils, the chemical structure itself is not clear.

Thiadiazole is a nitrogen-containing sulfur heterocyclic compound and its structure is not particularly limited. Nitrogen-containing heterocyclic compounds are preferred because they have high adsorptivity and can obtain a high effect of improving seizure resistance even in a small amount. For example, a 1,3,4-thiadiazole compound represented by the following general formula (5), a 1,2,4-thiadiazole compound represented by the following general formula (6), and a 1,4 represented by the general formula (7) , 5-thiadiazole compounds.

In the above formulas (5) to (7), R ^{1 to} R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 30 carbon atoms, and a, b, c, d, e and f. Are integers of 0 to 8, respectively.

Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group, a cycloalkyl group, an alkylcycloalkyl group, an alkenyl group, an aryl group, an alkylaryl group, and an arylalkyl group.

Examples of the thiadiazole include 2-amino-5-methyl-1,3,4-thiadiazole, 2,5-dimethyl-1,3,4-thiadiazole, 2,5-diethyl-1,3,4-thiadiazole. 2,5-bis(n-hexyldithio)-1,3,4-thiadiazole, 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-tetramethyl Butyldithio)-1,2,3-thiadiazole and mixtures thereof. Of these, 2,5-bis(1,1,3,3-tetramethylbutyldithio)-1,3,4-thiadiazole is preferable.

The amount of active sulfur of the above-mentioned sulfur-based extreme pressure agent is not particularly limited, but the amount of active sulfur is 30% by mass or less, preferably 15% by mass or less with respect to the mass of the extreme pressure agent. , And more preferably 13% by mass or less. If the amount of active sulfur exceeds the above upper limit, not only metal corrosion will occur, but also the occurrence of wear cannot be suppressed. The lower limit of the amount of active sulfur is not particularly limited, but in order to ensure extreme pressure, it is preferably 0.5% by mass or more, and more preferably 1% by mass with respect to the mass of the extreme pressure agent. % Or more, and more preferably 3% by mass or more.

Here, the amount of active sulfur is measured by the method specified in ASTM D1662. The amount of active sulfur based on ASTM D1662 can be measured in more detail by the following procedure.
1. Add 50 g of a sulfur-based additive (active sulfur-based extreme pressure agent) and 5 g of copper powder to a 200 ml beaker and raise the temperature to 150° C. with stirring with a stirrer.
2. When the temperature reaches 150° C., 5 g of copper powder is added, and the mixture is stirred for 30 minutes.
3. After completion of stirring, a copper plate conforming to ASTM D130 is placed in a beaker and immersed. At this time, if discoloration is observed on the copper plate, 5 g of copper powder is further added and stirred for 30 minutes (this operation is continued until discoloration is not observed).
4. When the copper plate is no longer discolored, the copper powder in the sulfur-based additive is removed by filtration, and the amount of sulfur contained in the additive is measured.
The amount of active sulfur is calculated as follows.
Active sulfur amount (mass %) = amount of sulfur before reaction with copper powder (% by mass)-sulfur amount after reaction with copper powder (% by mass)

The content of the sulfur-based extreme pressure agent in the lubricating oil composition of the present invention is not limited, but is preferably 0.1% by mass to 15% by mass, more preferably based on the mass of the entire lubricating oil composition. Is 0.2% to 12% by mass, more preferably 0.3% to 10% by mass. When the content exceeds the above upper limit, wear generation can be suppressed, but sludge is generated, which may cause metal corrosion in some cases, which is not preferable.

In the lubricating oil composition of the present invention, the sulfur content is not limited, but preferably 0.3 to 5% by mass, and more preferably 0.4 to 4% by mass with respect to the total mass of the lubricating oil composition. %, and more preferably 0.5 to 3 mass %. When the content exceeds the above upper limit, wear generation can be suppressed, but sludge is generated, which may cause metal corrosion in some cases, which is not preferable.

(D) Ashless Dispersant The lubricating oil composition of the present invention has a boron content of less than 50 ppm, preferably 40 ppm or less, more preferably 20 ppm or less, or does not contain boron. This makes it possible to provide a lubricating oil composition having a low viscosity and a low friction without gelation of the lubricating oil composition even if a polymer friction modifier described later is added. Therefore, in the present invention, the ashless dispersant may have no boron or have a boron content of less than 0.3% by mass, preferably 0.1% by mass or less. Particularly preferably, the lubricating oil composition should be free of boron and therefore ashless dispersants that are free of boron are preferred.

The ashless dispersant is not particularly limited as long as it has no boron or has 0.3% by mass or less of boron, and conventionally known ones may be used. For example, a nitrogen-containing compound having at least one alkyl group or alkenyl group having a straight chain structure or a branched structure having 40 to 400 carbon atoms in the molecule or a derivative thereof, or a modified product of alkenyl succinimide can be mentioned. .. The ashless dispersants may be used alone or in combination of two or more. When a borated ashless dispersant is used, it may be a borated ashless dispersant as described above. Boration is generally carried out by reacting a nitrogen-containing compound with boric acid to neutralize some or all of the remaining amino groups and/or imino groups.

The alkyl group or the alkenyl group has preferably 40 to 400 carbon atoms, and more preferably 60 to 350 carbon atoms. When the carbon number of the alkyl group and the alkenyl group is less than the lower limit value described above, the solubility of the compound in the lubricating base oil tends to decrease. When the carbon number of the alkyl group and the alkenyl group exceeds the above upper limit, the low temperature fluidity of the lubricating oil composition tends to deteriorate. The alkyl group and alkenyl group may have a linear structure or a branched structure. Preferred embodiments include, for example, olefin oligomers such as propylene, 1-butene and isobutylene, and branched alkyl groups or branched alkenyl groups derived from ethylene and propylene cooligomers.

The succinimide includes a so-called mono-type succinimide in which succinic anhydride is added to one end of a polyamine, and a so-called bis-type succinimide in which succinic anhydride is added to both ends of a polyamine. The lubricating oil composition of the present invention may contain either a monotype or a bis type, or may contain both.

For example, a method for producing borated succinimide is disclosed in Japanese Examined Patent Publications Nos. 42-8013 and 42-8014, JP-A-51-52381, JP-A-51-130408, and the like. The method etc. are mentioned. More specifically, alcohols, organic solvents such as hexane and xylene, polyamines and polyalkenylsuccinic acids (anhydrides) in light lubricating base oils such as boric acid, boric acid esters, or boron compounds such as borate salts. It can be obtained by mixing and heat treatment under appropriate conditions. The boron content contained in the borated succinimide thus obtained can be usually 0.1 to 4% by mass. In particular, a boron-modified compound of an alkenyl succinimide compound (boronated succinimide) is preferable because it has excellent heat resistance, antioxidation property, and antiwear property.

The content of boron contained in the borated ashless dispersant is not particularly limited as long as it does not exist at all or is 0.3% by mass or less. The borated ashless dispersant is preferably borated succinimide, and particularly preferably borated bissuccinimide. The borated ashless dispersant is not particularly limited in boron/nitrogen mass ratio (B/N ratio), but is one having 0.1 or more, preferably 0.2 or more, preferably less than 0.5, more preferably Is preferably 0.4 or less.
When two or more ashless dispersants are used, the content of boron in the total amount of the ashless dispersant may be 0.3% by mass or less, and for example, an ashless dispersant having 0.5% by mass of boron. And half of the ashless dispersant having no boron are mixed, the content of boron in the ashless dispersant is 0.25% by mass, which satisfies the requirement of the component (D).

The component (D) is preferably contained in the lubricating oil composition in an amount of 0.1 to 3% by mass, more preferably 0.1 to 2% by mass, and most preferably 0.2 to 1% by mass.

(E) Organic Polymer Friction Modifier The lubricating oil composition of the present invention is characterized by containing an organic polymer friction modifier having a specific structure. The organic polymer friction modifier has a unit derived from the following component (E1) and a unit derived from the following component (E2), has a weight average molecular weight of 5,000 to 100,000, and has the following ( It is a copolymer having a repeating unit derived from the component E1) and a repeating unit derived from the following component (E2) in a mass ratio of (E1):(E2)=95:5 to 60:40.
(E1) Alkyl (meth)acrylate (E2) having an alkyl group having 1 to 30 carbon atoms A hydroxyl group-containing (meth)acrylate represented by the following formula (8) or (9) CH ₂ =C(A ₁ ). -COOR ₁ -OH (8)
_{CH 2 = C (A 2)} -COOR 2 -O- [C (= O) -R 3 O] n -H (9)
(In the formula, R ₁ is an alkylene group having 1 to 30 carbon atoms, R ₂ is an alkylene group having 1 to 30 carbon atoms, R ₃ is an alkylene group having 1 to 8 carbon atoms, and A ₁ and A ₂ is a methyl group or a hydrogen atom, and n is an integer of 1 to 25)
The copolymer functions as a friction modifier. Specifically, it has a unit (oil-soluble skeleton) derived from the (E1) alkyl (meth)acrylate and a unit (skeleton having a polar group) derived from the (E2) hydroxyl group-containing alkyl (meth)acrylate. By including the copolymer, friction can be reduced, and the oil film can be maintained to improve the fatigue life. Since the polar group functions as an adsorptive group, by having the skeleton (E2) having a hydroxyl group in a mass ratio of (E1):(E2)=95:5 to 50:50, friction is effectively reduced. be able to. It is preferably (E1):(E2)=90:10 to 50:50, and more preferably (E1):(E2)=80:20 to 50:50. The weight average molecular weight of the copolymer is 5,000 to 100,000, preferably 5,000 to 90,000, and more preferably 10,000 to 90,000. The larger the weight average molecular weight is, the larger the effect of reducing friction becomes, which is preferable. The method for measuring the weight average molecular weight will be described later.

The component (E1) is an alkyl(meth)acrylate having an alkyl group having 1 to 30 carbon atoms. For example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, Hexadecyl (meth)acrylate, heptyldecyl (meth)acrylate, octadecyl (meth)acrylate and the like can be mentioned.

The above alkyl (meth)acrylates may be used alone or in combination of two or more. The component (E1) is preferably (E1-1) an alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms and (E1-2) an alkyl (meth)acrylate having an alkyl group having 9 to 30 carbon atoms. It is preferable to combine (E1-1) component:(E1-2) component (mass ratio)=20:80 to 0:100. By including the component (E1-1) and the component (E1-2), it is possible to further reduce the friction between the lubricating base oil and the metal member in contact therewith. In particular, since it is possible to further reduce friction by having a long-chain alkyl group, it is preferable to essentially contain (E1-2) an alkyl (meth)acrylate having an alkyl group having 9 to 30 carbon atoms.

Examples of the (E1-1) alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, and butyl. (Meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, and hexyl (meth)acrylate are mentioned. These may be used alone or in combination of two or more.

(E1-2) The alkyl(meth)acrylate having an alkyl group having 9 to 30 carbon atoms preferably has 13 to 28 carbon atoms, more preferably 15 to 28 carbon atoms, and most preferably 17 to 26 carbon atoms. It is preferably an alkyl (meth)acrylate. Examples thereof include tetradecyl (meth)acrylate, hexyldecyl (meth)acrylate, heptyldecyl (meth)acrylate, and octadecyl (meth)acrylate.

As described above, the component (E2) is a (meth)acrylate represented by the following (8) or (9), which has a hydroxyl group at the terminal and has an alkylene chain having 1 to 30 carbon atoms.
_{CH 2 = C (A 1)} -COOR 1 -OH (8)
_{CH 2 = C (A 2)} -COOR 2 -O- [C (= O) -R 3 O] n -H (9)
(In the formula, R ₁ is an alkylene group having 1 to 30 carbon atoms, R ₂ is an alkylene group having 1 to 30 carbon atoms, R ₃ is an alkylene group having 1 to 8 carbon atoms, and A ₁ and A ₂ is a methyl group or a hydrogen atom, and n is an integer of 1 to 25)

Examples of the (meth)acrylate represented by the general formula (8) include hydroxyalkyl (meth)acrylates having an alkylene chain having preferably 2 to 20 carbon atoms, and more preferably 2 to 10 carbon atoms. For example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxy. Examples thereof include butyl (meth)acrylate, 2-hydroxypentyl (meth)acrylate, 3-hydroxypentyl (meth)acrylate, 2-hydroxyhexyl (meth)acrylate, and 3-hydroxyhexyl (meth)acrylate.

The (meth)acrylate represented by the general formula (9) is obtained by subjecting the hydroxyalkyl (meth)acrylate represented by the general formula (8) and a lactone to ring-opening addition reaction. The starting hydroxyalkyl (meth)acrylate is as described above. For example, 2-hydroxyethyl (meth)acrylate is heated and reacted with a lactone. Known lactones can be used and are not particularly limited. Examples include α-acetolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone. The ring-opening addition reaction may be performed according to known conditions. For example, the reaction temperature is preferably 80 to 150°C, more preferably 100°C to 140°C. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours. The ring-opening addition reaction is preferably carried out under a catalyst, and tetrapropyl titanate, stannous octoate or the like can be used. It is preferable to add the catalyst in an amount of 0.01 to 5% by mass based on the amount of the reaction product. After completion of the reaction, the catalyst can be treated by a method of removing by adsorbing and filtering the catalyst with an adsorbent, a method of neutralizing and deactivating the catalyst.

Examples of the (meth)acrylate having the structure of the general formula (9) include hydroxypolyacetolactone mono(meth)acrylate (adding 1 to 25 mol of α-acetolactone), hydroxypolypropiolactone mono(meth)acrylate ( β-propiolactone added 1 to 25 mol), hydroxypolybutyrolactone mono(meth)acrylate (γ-butyrolactone added 1 to 25 mol), hydroxypolyvalerolactone mono(meth)acrylate (δ-valerolactone added 1 to 25 mol), and hydroxypolycaprolactone mono(meth)acrylate (addition of 1 to 25 mol of ε-caprolactone). Among these, hydroxypolycaprolactone mono(meth)acrylate (adding 1 to 25 mol of ε-caprolactone) is preferable, and hydroxypolycaprolactone mono(meth)acrylate (adding 1 to 20 mol of ε-caprolactone) is more preferable. Particularly, (meth)acrylate obtained by adding 1 to 20 mol of the lactone to 2-hydroxyethyl (meth)acrylate is preferable.

The component (E) is derived from the repeating unit derived from the component (E1) and the component (E2), and further derived from the amino group-containing (meth)acrylate represented by the following (10) or (11) (E3). It is preferable to further have a unit. The amino group also functions as an adsorption group.
_{CH 2 = C (A 1)} -COOR 1 -N (B 1) (B 2) (10)
_{CH 2 = C (A 2)} -COOR 2 -O- [C (= O) -R 3 NH] n -H (11)
(In the formula, R ₁ is an alkylene group having 1 to 30 carbon atoms, R ₂ is an alkylene group having 1 to 30 carbon atoms, R ₃ is an alkylene group having 1 to 10 carbon atoms, and A ₁ and A ₂ is each a methyl group or a hydrogen atom, B ₁ and B ₂ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 25).

The (meth)acrylate represented by the general formula (10) is preferably an aminoalkyl having an alkylene chain having 1 to 28 carbon atoms, more preferably 1 to 20 carbon atoms, and further preferably 1 to 18 carbon atoms. (Meth)acrylate is preferred. Examples of the aminoalkyl(meth)acrylate include N,N-dimethylaminoethyl(meth)acrylate, N,N-diethylaminoethyl(meth)acrylate, aminoethyl(meth)acrylate, aminopropyl(meth)acrylate, amino. Examples include butyl (meth)acrylate, aminoisobutyl (meth)acrylate, aminopentyl (meth)acrylate, and aminohexyl (meth)acrylate. N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylamino Ethyl (meth)acrylate is preferred.

The (meth)acrylate represented by the general formula (11) is obtained by subjecting the hydroxy(meth)acrylate represented by the above general formula (8) to a ring-opening reaction of a lactam. A known lactam can be used and is not particularly limited. For example, 2-hydroxyethyl (meth)acrylate is used as a raw material and a lactam is heated and reacted with it. The ring-opening addition reaction may be performed according to known conditions. For example, the reaction temperature is preferably 80 to 150°C, more preferably 100°C to 140°C. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours. The ring-opening addition reaction is preferably carried out under a catalyst, and tetrapropyl titanate, stannous octoate or the like can be used. It is preferable to add the catalyst in an amount of 0.01 to 5% by mass based on the amount of the reaction product. After completion of the reaction, the catalyst can be treated by a method of removing by adsorbing and filtering the catalyst with an adsorbent, a method of neutralizing and deactivating the catalyst.

Examples of the (meth)acrylate represented by the general formula (11) include aminopolypropiolactam mono(meth)acrylate (adding 1 to 100 mol of β-propiolactam), aminopolybutyrolactam mono(meth). Acrylate (adding 1 to 100 mol of γ-butyrolactam), aminopolyvalerolactam mono(meth)acrylate (adding 1 to 100 mol of δ-valerolactam), and aminopolycaprolactam mono(meth)acrylate (ε-caprolactam to 1 mol). ˜100 mol addition). Particularly, a (meth)acrylate obtained by adding 1 to 100 mol of the lactam to 2-hydroxyethyl (meth)acrylate is preferable.

The blending ratio of each structural unit in the copolymer (E) having a structural unit derived from the component (E3) is not particularly limited, but it is a repeating unit derived from the component (E1) or a component derived from the component (E2). And the repeating unit derived from the component (E3), the mass ratio of (E1):(E2):(E3)=90 to 50:5 to 45:5 to 20 (the total of the three ratios is 100. Yes, and more preferably has a mass ratio of (E1):(E2):(E3)=85-50:10-40:5-20 (the sum of the three ratios is 100). Is good.

The copolymerization of the components (E1), (E2) and (E3) may be carried out by a conventionally known method. For example, emulsion polymerization, suspension polymerization, solution polymerization and the like can be mentioned, but solution polymerization is preferable. In the case of solution polymerization, a solvent may be further added to the system after polymerization to produce a product, or a part or all of the solvent may be removed to produce a product. As a specific method of solution polymerization, for example, after charging the monomer (E1), the monomer (E2) and the monomer (E3) in a solvent so that the total monomer content becomes 5 to 80% by mass, The temperature may be raised to about 80 to 120° C., an amount of the initiator of 0.1 to 10 mol% with respect to the total amount of the monomer may be added all at once or in portions, and the reaction may be performed by stirring for 1 to 20 hours.

Examples of the solvent used for solution polymerization include alcohols such as methanol, ethanol, propanol and butanol; hydrocarbons such as benzene, toluene, xylene and hexane; esters such as ethyl acetate, butyl acetate and isobutyl acetate; acetone. Ketones such as methyl ethyl ketone and methyl isobutyl ketone; ethers such as methoxybutanol, ethoxybutanol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether and dioxane; paraffinic mineral oils, naphthenic mineral oils or hydrogenation of these Mineral oil such as refined refined mineral oil such as refining, solvent dewaxing, solvent extraction, solvent dewaxing, hydrodewaxing, catalytic dewaxing, hydrocracking, alkaline distillation, sulfuric acid washing, and clay treatment; , Ethylene-α-olefin copolymer, polybutene, alkylbenzene, alkylnaphthalene, polyphenyl ether, alkyl-substituted diphenyl ether, polyol ester, dibasic acid ester, hindered ester, monoester, GTL (Gas to Liquids) and other synthetic oils And mixtures thereof.

Examples of the initiator used for solution polymerization include 2,2′-azobis(2-methylpropionitrile), 2,2′-azobis(2-amidinopropane) dihydrochloride, 2,2′-azobis- (N,N-dimethyleneisobutylamidine) dihydrochloride, azo-based initiators such as 1,1′-azobis(cyclohexyl-1-carbonitrile), hydrogen peroxide and benzoyl peroxide, t-butyl hydroperoxide, Cumene hydroperoxide, methyl ethyl ketone peroxide, organic peroxides such as perbenzoic acid, sodium persulfate, potassium persulfate, persulfates such as ammonium persulfate, redox initiators such as hydrogen peroxide-Fe ²⁺ , and other existing Radical initiators may be used. The extreme pressure agent for lubricating oil of the present invention must have a specific molecular weight, but the molecular weight at the time of synthesis may be controlled by a known method, for example, reaction temperature, amount of initiator, charging of monomer. Method, type of solvent, use of chain transfer agent, etc.

As described above, the weight average molecular weight of the (E) copolymer is 5,000 to 100,000, preferably 5,000 to 90,000, and more preferably 10,000 to 90,000. In the present invention, the weight average molecular weight of the copolymer is measured by gel permeation chromatography under the following conditions and obtained in terms of polystyrene.
Device: "HLC-802A" [manufactured by Tosoh Corporation]
Column: "TSK gel GMH6" [manufactured by Tosoh Corporation] 2 measuring temperatures: 40°C
Sample solution: 0.5 wt% tetrahydrofuran solution Injection volume: 200 μl
Detection device: Refractive index detector Reference substance: Standard polystyrene (TSK standard POLYSTYRENE) 12 points (molecular weight: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400) , 190,000, 355,000, 1,090,000, 2,890,000) [manufactured by Tosoh Corporation]

The amount of the component (E) in the lubricating oil composition is preferably 0.01 to 30% by mass, more preferably 0.2 to 25% by mass, based on the total mass of the lubricating oil composition. The amount is more preferably 0.5 to 15% by mass, and particularly preferably 0.8 to 5% by mass. If it is less than the lower limit value, the initial friction coefficient may increase. If the amount is more than the upper limit, the kinematic viscosity becomes too high and the fuel economy may be impaired.

(F) Friction Modifier Having Molybdenum The lubricating oil composition of the present invention preferably further comprises (F) a friction modifier having molybdenum. The (F) molybdenum-containing friction modifier may be any conventionally known compound and is not particularly limited. For example, sulfur-containing organomolybdenum compounds such as molybdenum dithiophosphate (MoDTP) and molybdenum dithiocarbamate (MoDTC), complexes of molybdenum compounds with sulfur-containing organic compounds or other organic compounds, and molybdenum sulfide and molybdenum sulfide. Examples thereof include a complex of a sulfur-containing molybdenum compound and an alkenylsuccinimide. Examples of the molybdenum compound include molybdenum oxide such as molybdenum dioxide and molybdenum trioxide, molybdic acid such as ortho-molybdic acid, para-molybdic acid and (poly)sulfurized molybdic acid, and molybdenum such as metal salts and ammonium salts of these molybdic acids. Examples thereof include acid salts, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide and polymolybdenum sulfide, molybdenum sulfide, molybdenum sulfide, metal salts or amine salts of molybdenum sulfide, molybdenum halides such as molybdenum chloride and the like. Examples of the sulfur-containing organic compound include alkyl(thio)xanthate, thiadiazole, mercaptothiadiazole, thiocarbonate, tetrahydrocarbyl thiuram disulfide, bis(di(thio)hydrocarbyl dithiophosphonate) disulfide, and organic (poly)sulfide. And sulfurized esters. In particular, organic molybdenum compounds such as molybdenum dithiophosphate (MoDTP) and molybdenum dithiocarbamate (MoDTC) are preferable.

Molybdenum dithiocarbamate (MoDTC) is a compound represented by the following formula [I], and molybdenum dithiophosphate (MoDTP) is a compound represented by the following [II].

In the above general formulas [I] and [II], R _{1 to} R ₈ may be the same or different from each other and are a monovalent hydrocarbon group having 1 to 30 carbon atoms. The hydrocarbon group may be linear or branched. As the monovalent hydrocarbon group, a linear or branched alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; a cycloalkyl group having 4 to 30 carbon atoms; an aryl having 6 to 30 carbon atoms Group, an alkylaryl group, an arylalkyl group, and the like. In the arylalkyl group, the bonding position of the alkyl group is arbitrary. More specifically, as the alkyl group, for example, 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. , A tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, and the like, and branched alkyl groups thereof, and an alkyl group having 3 to 8 carbon atoms is particularly preferable. Further, X ₁ and X ₂ are oxygen atoms or sulfur atoms, and Y ₁ and Y ₂ are oxygen atoms or sulfur atoms.

As the component (F), an organic molybdenum compound containing no sulfur can also be used. Examples of such a compound include a molybdenum-amine complex, a molybdenum-succinimide complex, a molybdenum salt of an organic acid, and a molybdenum salt of an alcohol.

Further, as the friction modifier (F) having molybdenum in the present invention, the trinuclear molybdenum compound described in US Pat. No. 5,906,968 can be used.

The amount of the component (F) in the lubricating oil composition is preferably 100 ppm to 1500 ppm as the amount of molybdenum atoms, more preferably 200 ppm to 1400 ppm, and most preferably 250 ppm to 1300 ppm. When it is less than the lower limit value, long-term friction characteristics may be improved. If the amount is more than the upper limit, deposits may occur and the cleanliness may be poor.

In the present invention, in order to realize low friction, the component (B) has one or two (B3) alkyl groups, each of which has 4 to 10 carbon atoms, At least one selected from the group consisting of acidic phosphoric acid ester, (B4) phosphite ester, and (B5) phosphonic acid ester, and further containing (F) component from molybdenum dithiophosphate (MoDTP) and molybdenum dithiocarbamate (MoDTC) It is preferable to include at least one selected.
As a result, in addition to wear characteristics and scoring resistance, low friction can be realized, and it becomes possible to contribute to further fuel saving.

Other additives The lubricating oil composition of the present invention may contain other known additives in addition to the components (A) to (F). For example, a friction modifier other than the components (E) and (F), an antiwear agent, a metal detergent, an extreme pressure agent other than the component (B), an antioxidant, a metal deactivator, and a viscosity index improver. , Antifoaming agents, pour point depressants, demulsifiers, and rust inhibitors. These additives may be used alone or in combination of two or more.

Examples of the friction modifier that does not correspond to the components (E) and (F) include esters, amines, amides, and sulfurized esters. When the above friction modifier is used, it is usually blended in the lubricating oil composition in an amount of 0.01 to 3% by mass.

As the antiwear agent, conventionally known ones can be used. Of these, antiwear agents containing phosphorus are preferable, and zinc dithiophosphate (ZnDTP (also referred to as ZDDP)) represented by the following formula is particularly preferable.

In the above formula, R ¹ and R ^{2, which} may be the same or different, are each a hydrogen atom or a monovalent hydrocarbon group having 1 to 26 carbon atoms. As the monovalent hydrocarbon group, a primary (primary) or secondary (secondary) alkyl group having 1 to 26 carbon atoms; an alkenyl group having 2 to 26 carbon atoms; a cycloalkyl group having 6 to 26 carbon atoms; carbon An aryl group, an alkylaryl group or an arylalkyl group of the formulas 6 to 26; or a hydrocarbon group containing an ester bond, an ether bond, an alcohol group or a carboxyl group. R ¹ and R ² are preferably a primary or secondary alkyl group having 2 to 12 carbon atoms, a cycloalkyl group having 8 to 18 carbon atoms, and an alkylaryl group having 8 to 18 carbon atoms, and They may be the same as or different from each other. In particular, zinc dialkyldithiophosphate is preferable, and the primary alkyl group preferably has 3 to 12 carbon atoms, and more preferably 4 to 10 carbon atoms. The secondary alkyl group preferably has 3 to 12 carbon atoms, and more preferably 3 to 10 carbon atoms. The zinc dithiophosphates may be used alone or in combination of two or more. Further, zinc dithiocarbamate (ZnDTC) may be used in combination.

When an antiwear agent is used, it is usually added to the lubricating oil composition in an amount of 0.1 to 5.0% by mass, preferably 0.2 to 3.0% by mass.

Known metal detergents can be used. For example, detergents with alkali metals or alkaline earth metals can be used. It is preferable to use sodium, calcium, magnesium, and barium as the alkali metal or alkaline earth metal.

Examples of the metal detergent include sodium salicylate, sodium sulfonate, sodium phenate, sodium carboxylate, calcium salicylate, calcium sulfonate, calcium phenate, calcium carboxylate, magnesium salicylate, magnesium sulfonate, magnesium phenate, and magnesium carboxylate. Is mentioned. Among these, calcium salicylate, calcium sulfonate, calcium phenate, calcium carboxylate, magnesium salicylate, magnesium sulfonate, magnesium phenate, and magnesium carboxylate are preferable, and calcium salicylate, calcium sulfonate, magnesium salicylate, and magnesium sulfonate are more preferable. .. These metal detergents may be used alone or in combination of two or more. When two or more kinds are used together, it is possible to use the same kind (for example, calcium salicylate) but different base numbers. When used in combination, the calcium detergent and the magnesium detergent may be used together so that one kind selected from calcium salicylate and calcium sulfonate and one kind selected from magnesium salicylate and magnesium sulfonate are mixed. Good.

The base number of the metal detergent is preferably 5 to 450 mg/KOH·g, more preferably 70 to 400 mg/KOH·g, most preferably 100 to 400 mg/KOH·g.

A publicly known thing can be used for a metal deactivator. Examples thereof include benzotriazole and 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate. The metal deactivator is not particularly limited, but it is preferably blended in the lubricating oil composition in an amount of 0.01 to 5% by mass.

A well-known thing can be used for a viscosity index improver. As the viscosity index improver, for example, polymethacrylate, dispersion type polymethacrylate, olefin copolymer (polyisobutylene, ethylene-propylene copolymer), dispersion type olefin copolymer, polyalkylstyrene, styrene-butadiene hydrogenated copolymer, Examples thereof include those containing a styrene-maleic anhydride copolymer, star-shaped isoprene and the like. Further, a comb polymer having at least a repeating unit based on a polyolefin macromer and a repeating unit based on an alkyl (meth)acrylate having an alkyl group having 1 to 30 carbon atoms can be used.

Viscosity index improvers usually consist of the above polymers and diluent oil. When it is not necessary to reduce the viscosity, it is not particularly limited, but 0.001 to 20% by mass is preferably added, 0.1 to 20% by mass is more preferably added, and 1 to 15% by mass is added. Preferably. However, in order to reduce the viscosity, it is preferable not to add it, and even if it is added, it is preferably 0.001 to 1% by mass in the lubricating oil composition, and 0.001 to 0.5 It is more preferable to use the mass.

Examples of the defoaming agent include silicone oil having a kinematic viscosity at 25° C. of 1000 to 100,000 mm ² /s, alkenyl succinic acid derivative, ester of polyhydroxy aliphatic alcohol and long chain fatty acid, methyl salicylate and o-. Examples thereof include hydroxybenzyl alcohol. The content of the defoaming agent is not limited, but is 0.001 to 1% by mass in the lubricating oil composition.

As the pour point depressant, for example, a polymethacrylate-based polymer compatible with the lubricating base oil used can be used. The content of the pour point depressant is not limited, but is preferably 0.01 to 3 mass% in the lubricating oil composition.

Examples of the demulsifier include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and polyoxyethylene alkylnaphthyl ether. The content of the demulsifier is not limited, but is preferably 0.01 to 5 mass% in the lubricating oil composition.

Examples of the rust preventive agent include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester. The content of the rust preventive agent is not limited, but is preferably 0.01 to 5 mass% in the lubricating oil composition.

Lubricating Oil Composition The kinematic viscosity of the lubricating oil composition has a kinematic viscosity at 100° C. of ^{2 to 10} mm ² /s, preferably ^{2 to} 8 mm ² /s, and preferably 3 to 8 mm, in order to secure fuel economy. It is preferably ² /s.
The sulfur content in the lubricating oil composition is not limited, but is preferably 0.3 to 5% by mass, more preferably 0.4 to 4% by mass, and further preferably 0.5 to 3% by mass.
The phosphorus content in the lubricating oil composition is not limited, but is preferably 200 to 2000 ppm, more preferably 200 to 1900 mass ppm, and further preferably 300 to 1700 mass ppm.
The molybdenum content in the lubricating oil composition is not limited, but is preferably 100 to 1500 ppm, more preferably 100 to 1200 mass ppm, and most preferably 250 to 1000 mass ppm.

The lubricating oil composition of the present invention is not particularly limited, but it can be suitably used as a lubricating oil for automobiles, particularly as a lubricating oil for hybrid automobiles.
Further, the lubricating oil composition of the present invention can be suitably used particularly as a lubricating oil for a transmission oil and a lubricating oil for a gear oil.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.
The components constituting the lubricating oil compositions of Examples and Comparative Examples are as follows.
(A) Lubricating base oil (A1) GTL base oil (hereinafter sometimes referred to as "GTL-4")
(Kinematic viscosity at 100° C.=4.2 mm ² /s, viscosity index=122, %Cp=100%, %Cn=0%)
(A2) GTL base oil (hereinafter sometimes referred to as "GTL-8").
(Kinematic viscosity at 100° C.=8.0 mm ² /s, viscosity index=124, %Cp=100%, %Cn=0%)
(B) Phosphorus-based extreme pressure agent (B1) Phosphate ester amine salt (mixture of those having an alkyl group having 8 to 12 carbon atoms)
(B2) Thiophosphate ester amine salt (mixture of those having an alkyl group having 8 to 12 carbon atoms)
(B3) Acidic phosphoric acid ester having an alkyl group having 4 carbon atoms (B4) Phosphorous acid ester having an alkyl group having 4 carbon atoms (B5) Phosphonic acid ester having an alkyl group having 18 carbon atoms (C) Sulfur-based electrode Pressure agent (C1) Sulfurized olefin (amount of active sulfur; 11 mass%)
(C2) sulfurized ester (active sulfur amount: 1.4 mass%)
(C3) Sulfurized oil and fat (amount of active sulfur; 4.1 mass%)
(D) Ashless dispersant (D1) Polyisobutenyl succinimide (bisimide type, molecular weight of polybutenyl group: 1,400, nitrogen 2.0 mass%, boron 0.0 mass%)
(D2) Boron-modified polyisobutenyl succinimide (bisimide type, molecular weight of polybutenyl group: 2,000, nitrogen 1.7% by mass, boron 1.9% by mass)
(D3) Boron-modified polyisobutenyl succinimide (bisimide type, molecular weight of polybutenyl group: 3,000, nitrogen 2.0% by mass, boron 1.3% by mass)

(E) Organic polymer-based friction modifier In the following friction modifiers 1 to 6, the hydroxyl group-containing acrylate is hydroxyethyl acrylate (HEA) to which 5 mol of caprolactone is added. The hydroxyl group-containing methacrylate is obtained by adding 10 mol of caprolactone to hydroxyethyl methacrylate (HEMA). The amino group-containing methacrylate is N,N-dimethylaminoethyl methacrylate.
Friction modifier 1 (E-1)
(E1-2) A unit derived from an alkyl methacrylate having an alkyl group having 9 to 30 carbon atoms, a unit derived from (E2) a hydroxyl group-containing acrylate, and a unit derived from (E3) an amino group-containing methacrylate. Copolymer having a ratio of 52:38:10 (weight average molecular weight 80,000)
Friction modifier 2 (E-2)
(E1-1) a unit derived from an alkyl methacrylate having an alkyl group having 1 to 8 carbon atoms, (E1-2) a unit derived from an alkyl methacrylate having an alkyl group having 9 to 30 carbon atoms, and (E2) a hydroxyl group Copolymer having units derived from contained acrylate in a mass ratio of 10:52:38 (weight average molecular weight 80,000)
Friction modifier 3 (E-3)
(E1-1) a unit derived from an alkyl methacrylate having an alkyl group having 1 to 8 carbon atoms, (E1-2) a unit derived from an alkyl methacrylate having an alkyl group having 9 to 30 carbon atoms, and (E2) a hydroxyl group Copolymer having units derived from contained methacrylate in a mass ratio of 10:52:38 (weight average molecular weight 80,000)
Friction modifier 4 (E-4)
(E1-1) a unit derived from an alkyl methacrylate having an alkyl group having 1 to 8 carbon atoms, (E1-2) a unit derived from an alkyl methacrylate having an alkyl group having 9 to 30 carbon atoms, and (E2) a hydroxyl group Copolymer having units derived from contained methacrylate in a mass ratio of 10:52:38 (weight average molecular weight 50,000)
Friction modifier 5 (E-5)
(E1-1) a unit derived from an alkyl methacrylate having a C1-8 alkyl group, (E1-2) a unit derived from an alkyl methacrylate having a C9-30 alkyl group, and (E2) a hydroxyl group-containing Copolymer having a unit derived from methacrylate and a unit derived from (E3) amino group-containing methacrylate in a mass ratio of 10:50:30:10 (weight average molecular weight 80,000).
Friction modifier 6 (E-6)
(E1-1) a unit derived from an alkyl methacrylate having an alkyl group having 1 to 8 carbon atoms, (E1-2) a unit derived from an alkyl methacrylate having an alkyl group having 9 to 30 carbon atoms, and (E2) a hydroxyl group Copolymer having units derived from contained acrylate in a mass ratio of 10:52:38 (weight average molecular weight 125,000)

(F) Molybdenum friction modifier (F1) Molybdenum dithiocarbamate (MoDTC, molybdenum content 10% by mass)
(F2) Molybdenum dithiophosphate (MoDTP, molybdenum content 9% by mass)
(G) Other additives Oleic acid amide, pour point depressant

[Examples 1 to 14 and Comparative Examples 1 to 3]
Lubricating oil compositions were prepared by blending the components described above in the compositions and amounts shown in Table 1, Table 3, or Table 5. The blending amount is parts by mass with respect to the total amount of the lubricating oil composition (100 parts by mass), but the content in parentheses is the amount of each element (ppm). The following tests were conducted on these lubricating oil compositions. The results are shown in Tables 2, 4, and 7. Reference Examples 1 and 2 are conventional boron-containing lubricating oil compositions having a kinematic viscosity at 100° C. of 11.4 mm ² /s. The same test was performed on the composition.
(1) Kinematic viscosity at 40°C and 100°C (KV40, KV100)
Measured according to ASTM D445.
(2) Viscosity index
It was measured according to JIS K2283.
(3) Coefficient of friction:
A standard test piece made of PCS Instruments made of a plate test piece (material: AISI 52100 steel) and a standard test piece made of PCS Instruments made of a ball test piece (material: AISI 52100 steel) having a diameter of 0.75 inch which is a counterpart. A ball-on-disk friction test was conducted for each lubricating oil composition. A ball-on-disk friction test was conducted under a test load of 37 N, a slip ratio of 50%, and an oil temperature of 100° C.), and the average friction coefficient at a slip speed of 0.05 to 0.2 m/s immediately after the start of the test was taken as the friction coefficient in this test. .. A friction coefficient of 0.07 or less was accepted.
(4) Storage stability Put 100 ml of sample oil into a glass tube of the shape and size specified in JIS K 2503 type I scale test tube, and put the test tube in an electrothermal constant temperature air bath capable of continuous operation at 60°C. Stored at 60°C for 1 month. After that, the presence or absence of precipitates or precipitates was confirmed in the test tube.

(5) Abrasion scar diameter Using a four-ball abrasion tester specified by ASTM D4172, a test was conducted under the conditions of oil temperature 40°C, load 40 kgf, rotation speed: 100 rpm, time 60 minutes, and the abrasion scar diameter after the test was completed. It was measured. It is good if the wear scar diameter is 0.40 mm or less.
(6) Evaluation of Scoring Property A four-ball abrasion tester specified by ASTM D4172 was used to perform a test under the following conditions, and the number of revolutions when seizure occurred was recorded. Oil temperature: room temperature, load: 100 kgf, rotation speed: 100 rpm increments every 30 seconds. The case where the number of rotations (rpm) was 1000 or more was regarded as acceptable.

As shown in Table 7 above, when the viscosity of the conventional boron-containing lubricating oil composition shown in Reference Example is lowered, the friction coefficient becomes large as shown in Comparative Example 3. In addition, when a copolymer having a unit derived from a hydroxyl group-containing acrylate as a polymer friction modifier is added to the lubricating oil composition of Comparative Example 3, the lubricating oil composition is gelated, resulting in kinematic viscosity and the like. Measurement is not possible (Comparative Example 1). Even if the boron content in the lubricating oil composition is reduced to 60 ppm, the situation does not change (Comparative Example 4). On the other hand, as shown in Tables 1 to 4, the content of boron in the lubricating oil composition is less than 50 ppm, and in particular, the lubricating oil composition containing no boron contains a copolymer having a unit derived from a hydroxyl group-containing acrylate. By doing so, the lubricating oil composition does not gel, has a low viscosity, and can have a friction as low as that of a lubricating oil composition having a conventional viscosity (Reference Example) (Example 1). ~3, 7-10).
Further, the larger the weight average molecular weight of the copolymer is, the more the friction can be reduced. However, as shown in Comparative Example 2 in Table 7, when the weight average molecular weight of the copolymer is too large, the lubricating oil composition has It does not dissolve and precipitates over time. On the other hand, the lubricating oil composition of the present invention does not cause precipitation over time and is excellent in storage stability.

Furthermore, the lubricating oil composition of the present invention further contains specific phosphorus extreme pressure agents (B3) to (B5) as shown in Examples 4 to 6 and Examples 11 to 14 of Tables 1 to 4. By blending, it has low viscosity, storage stability, and low friction, and can further improve wear resistance and scoring resistance.

Claims (19)

A lubricating oil composition comprising the following components (A) to (E), wherein (A) a lubricating base oil,
(B) phosphorus-based extreme pressure agent,
(C) Sulfur-based extreme pressure agent,
(D) an ashless dispersant, and (E) a unit derived from the following component (E1) and a unit derived from the following component (E2), having a weight average molecular weight of 5,000 to 100,000, Copolymer (E1) having a repeating unit derived from the following component (E1) and a repeating unit derived from the following component (E2) in a mass ratio of (E1):(E2)=95:5 to 50:50 (E1) having 1 to 30 alkyl group, the alkyl (meth) acrylate (E2) the following formula (1) or (2) a hydroxyl group-containing represented by (meth) acrylate _{CH 2 = C (a 1)} -COOR 1 -OH (1)
_{CH 2 = C (A 2)} -COOR 2 -O- [C (= O) -R 3 O] n -H (2)
(In the formula, R ₁ is an alkylene group having 1 to 30 carbon atoms, R ₂ is an alkylene group having 1 to 30 carbon atoms, R ₃ is an alkylene group having 1 to 8 carbon atoms, and A ₁ and A ₂ is a methyl group or a hydrogen atom, and n is an integer of 1 to 25)
The lubricating oil composition has a kinematic viscosity at 100° C. of ^{2 to} 10 mm ² /s, and
The above lubricating oil composition is characterized in that the content of boron in the lubricating oil composition is less than 50 ppm or does not contain boron. The lubricating oil composition CH according to claim 1, wherein the copolymer (E) further has a unit (E3) derived from an amino group-containing (meth)acrylate represented by the following formula (3) or (4). _{2 = C (A 1) -COOR} 1 -N (B 1) (B 2) (3)
_{CH 2 = C (A 2)} -COOR 2 -O- [C (= O) -R 3 NH] n -H (4)
(In the formula, R ₁ is an alkylene group having 1 to 30 carbon atoms, R ₂ is an alkylene group having 1 to 30 carbon atoms, R ₃ is an alkylene group having 1 to 10 carbon atoms, and A ₁ and A ₂ are each a methyl group or a hydrogen atom, _{B 1} and _{B 2,} independently of one another, a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, n is an integer from 1 to 25). The copolymer (E) has a repeating unit derived from the component (E1), a repeating unit derived from the component (E2), and a repeating unit derived from the component (E3) (E1):(E2):(E3)=90. The lubricating oil composition according to claim 1, having a mass ratio of -50:5 to 45:5-20 (the sum of the three ratios is 100). The component (E1) is a combination of the following component (E1-1) and the following component (E1-2), and the mass ratio (E1-1) component:(E1-2) component=20:80 to 0:100. The lubricating oil composition according to any one of claims 1 to 3, (E1-1) having an alkyl group having 1 to 8 carbon atoms, (meth)acrylate (E1-2) having 9 to 30 carbon atoms. Alkyl (meth)acrylate having an alkyl group of. As the phosphorus-based extreme pressure agent (B),
The (B1) amine salt of a phosphoric acid ester having an alkyl group having 4 to 30 carbon atoms, and (B2) at least one selected from the amine salt of thiophosphoric acid ester according to any one of claims 1 to 4. Lubricating oil composition. The (B) phosphorus-based extreme pressure agent further comprises an acidic phosphoric acid ester having one or two (B3) alkyl groups, each of which has 4 to 10 carbon atoms. The lubricating oil composition described in 1. As the phosphorus-based extreme pressure agent (B),
The lubricating oil composition according to claim 5 or 6, further comprising at least one selected from (B4) phosphite ester and (B5) phosphonate ester. The lubricating oil composition according to any one of claims 1 to 7, wherein the (C) sulfur-based extreme pressure agent is at least one selected from sulfurized olefins, sulfurized fats and oils, sulfurized esters, polysulfides, and thiadiazole. The lubricating oil composition according to any one of claims 1 to 8, wherein the (C) sulfur-based extreme pressure agent has an active sulfur amount of 0.5 to 30 mass%. The lubricating oil composition according to any one of claims 1 to 9, wherein the (D) ashless dispersant has a boron content of less than 0.3% by mass. The lubricating oil composition according to any one of claims 1 to 9, wherein the (D) ashless dispersant does not contain boron. The lubricating oil composition according to any one of claims 1 to 11, further comprising (F) a friction modifier having molybdenum. The lubricating oil composition according to claim 12, wherein the friction modifier having molybdenum (F) is at least one selected from molybdenum dithiocarbamate (MoDTC) and molybdenum dithiophosphate (MoDTP). The lubricating oil composition according to any one of claims 1 to 13, wherein a sulfur content in the lubricating oil composition is 0.3 to 5% by mass. The lubricating oil composition according to any one of claims 1 to 14, wherein the phosphorus content in the lubricating oil composition is 200 to 2000 ppm. The lubricating oil composition according to any one of claims 12 to 15, wherein the molybdenum content in the lubricating oil composition is 100 to 1500 ppm. The lubricating oil composition according to any one of claims 1 to 16, which is for a hybrid vehicle. The lubricating oil composition according to any one of claims 1 to 17, which is used for a transmission oil. The lubricating oil composition according to any one of claims 1 to 17, which is used for gear oil.