JP2022151618A - Lubricant composition - Google Patents

Abstract

To provide a lubricant composition capable of achieving both cooling properties and lubricating properties.SOLUTION: A lubricant composition comprises: a copolymer (A) consisting of a monomer (a) represented by a general formula (1), and a monomer (b) represented by a general formula (2) and/or a monomer (c) represented by a general formula (3) as essential constituent monomers, and an ester oil (B). Preferably, the weight average molecular weight of the copolymer (A) is 5,000 to 2,000,000, and the solubility parameter of the copolymer (A) is 8.5 to 11.5 (cal/cm3)1/2.SELECTED DRAWING: Figure 1

Description

The present invention relates to lubricating oil compositions.

In recent years, in order to improve fuel efficiency, automobile transmissions are required to have improved power transmission efficiency and to be smaller and lighter. It is now installed in some vehicles. On the other hand, electric vehicles equipped with lead-acid batteries, nickel-metal hydride batteries, lithium-ion batteries, fuel cells, etc. and equipped with electric motors, or hybrid vehicles using these batteries in combination with an internal combustion engine have been developed. In automobiles, transmission oil and electric motor oil are used separately.

Recently, in electric vehicles and hybrid vehicles, there is a growing demand for common use of these oils and for downsizing and weight reduction by packaging transmissions and electric motors. In addition to the lubricating performance as an electric motor oil, there has been a demand for a new oil that has both insulating and cooling properties as an electric motor oil.
Transmission oils are required to have thermal/oxidative stability, detergent/dispersant properties, anti-wear properties, anti-seizure properties, and the like. In order to satisfy these requirements, transmission oils generally contain mineral or synthetic base oils with various additives (antioxidants, detergent dispersants, antiwear agents, rust inhibitors, metal deactivators, friction modifiers). , deodorants, colorants, seal swelling agents, viscosity index improvers, etc.) are used. Such transmission oil has low volume resistivity and insufficient insulation. and power loss.

On the other hand, electric motor oil is required to have insulating properties, cooling properties, etc., and does not require lubricating properties, so it contains almost no additives. Therefore, when the electric motor oil is used in the transmission, there is a problem that the bearings, gears, etc. are significantly worn. In addition, in electric motors, due to the progress of miniaturization and high rotation speed, there are increasing expectations for the cooling performance of lubricating oil. That is, in a vehicle equipped with an electric motor such as an electric vehicle or a hybrid vehicle, it has anti-seizure performance, anti-wear performance, and low-temperature fluidity performance as a transmission oil, and also has better insulation and cooling performance than before. There is a need for a machine oil composition.
To use an ester-based synthetic oil having high thermal conductivity, such as an ester of a monohydric alcohol and a monobasic acid and/or an ester of a monohydric alcohol and a polybasic acid, as a transmission oil composition for automobiles that also has cooling properties. is known (Patent Documents 1 and 2).
However, although the above composition has a low viscosity, a good heat transfer coefficient, and a high cooling property, the low viscosity causes the oil film to become thin, which increases the coefficient of friction and deteriorates the lubricity.

JP 2009-242547 A JP 2014-25081 A

An object of the present invention is to provide a lubricating oil composition that achieves both cooling properties and lubricating properties.

［式（１）中、Ａ^１は１価のラジカル重合性基であり、－Ｘ^１－、－Ｘ^２－及び－Ｘ^３－はそれぞれ独立に－Ｏ－又は－ＮＨ－で表される基であり、Ｒ^１は炭素数１～４のアルキレン基であり、Ｒ^２はそれぞれ独立に炭素数２～２０のアルキレン基であり、複数個ある場合のＲ^２は同一でも異なっていてもよく、Ｒ^３は水素原子、炭素数１～４４のアルキル基、炭素数２～４５のアシル基、炭素数１～４４のアルキル基で置換されていてもよいフェニル基又はベンゾイル基であり、ｐは１～１００の整数である。］

［式（２）中、Ｒ^４は水素原子又はメチル基；－Ｘ^４－は－Ｏ－又は－ＮＨ－で表される基；Ｒ^５は炭素数５～４４の直鎖状又は分岐鎖状のアルキル基である。］

［式（３）中、Ｒ^６は水素原子又はメチル基；－Ｘ^５－は－Ｏ－、－Ｏ（ＡＯ）_ｍ－又は－ＮＨ－で 表される基であって、Ａは炭素数２～４のアルキレン基であり、ｍは１～１０の整数であり、ｍが２以上の場合のＡは同一でも異なっていてもよい；Ｒ^７はイソブチレン基及び／又は１，２－ブチレン基を必須構成単位とする炭素数４３以上の炭化水素重合体から水素原子を１つ除いた残基；ｑは０又は１の数である。］ The present inventors arrived at the present invention as a result of earnest studies. That is, the present invention includes a monomer (a) represented by the following general formula (1) and a monomer (b) represented by the following general formula (2) and/or represented by the following general formula (3) It is a lubricating oil composition containing a copolymer (A) having a monomer (c) as an essential constituent monomer and an ester oil (B).

[In the formula (1), A ¹ is a monovalent radically polymerizable group, and -X ¹ -, -X ² - and -X ³ - are each independently a group represented by -O- or -NH- wherein R ¹ is an alkylene group having 1 to 4 carbon atoms, each R ² is independently an alkylene group having 2 to 20 carbon atoms, and when there are a plurality of R ² may be the same or different, R ³ is a hydrogen atom, an alkyl group having 1 to 44 carbon atoms, an acyl group having 2 to 45 carbon atoms, a phenyl group or a benzoyl group optionally substituted with an alkyl group having 1 to 44 carbon atoms, and p is 1 An integer from ˜100. ]

[In the formula ( ² ), R ⁴ is a hydrogen atom or a methyl group; -X ⁴ - is a group represented by -O- or -NH-; is an alkyl group of ]

[wherein R ⁶ is a hydrogen atom or a methyl group; -X ⁵ - is a group represented by -O-, -O(AO) _m - or -NH-, and A has 2 carbon atoms; to 4 alkylene groups, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different; R ⁷ is an isobutylene group and/or a 1,2-butylene group; A residue obtained by removing one hydrogen atom from a hydrocarbon polymer having 43 or more carbon atoms as an essential structural unit; q is the number of 0 or 1; ]

The lubricating oil composition of the present invention has the effect of achieving both cooling properties and lubricating properties.

1 shows the relationship between the rotation speed and the MTM friction coefficient in measuring the MTM friction coefficient at 100° C. of the lubricating oil compositions (V-1) to (V-4) of Examples 1 to 4. In the MTM friction coefficient measurement at 100 ° C. of the lubricating oil compositions (V'-1), (V'-3), (V'-5) to (V'-8) of Comparative Examples 1, 3, 5 to 8 , the relationship between the rotational speed and the MTM friction coefficient.

［式（１）中、Ａ^１は１価のラジカル重合性基であり、－Ｘ^１－、－Ｘ^２－及び－Ｘ^３－はそれぞれ独立に－Ｏ－又は－ＮＨ－で表される基であり、Ｒ^１は炭素数１～４のアルキレン基であり、Ｒ^２はそれぞれ独立に炭素数２～２０のアルキレン基であり、複数個ある場合のＲ^２は同一でも異なっていてもよく、Ｒ^３は水素原子、炭素数１～４４のアルキル基、炭素数２～４５のアシル基、炭素数１～４４のアルキル基で置換されていてもよいフェニル基又はベンゾイル基であり、ｐは１～１００の整数である。］

［式（２）中、Ｒ^４は水素原子又はメチル基；－Ｘ^４－は－Ｏ－又は－ＮＨ－で表される基；Ｒ^５は炭素数５～４４の直鎖状又は分岐鎖状のアルキル基である。］

［式（３）中、Ｒ^６は水素原子又はメチル基；－Ｘ^５－は－Ｏ－、－Ｏ（ＡＯ）_ｍ－又は－ＮＨ－で 表される基であって、Ａは炭素数２～４のアルキレン基であり、ｍは１～１０の整数であり、ｍが２以上の場合のＡは同一でも異なっていてもよい；Ｒ^７はイソブチレン基及び／又は１，２－ブチレン基を必須構成単位とする炭素数４３以上の炭化水素重合体から水素原子を１つ除いた残基；ｑは０又は１の数である。］ The lubricating oil composition of the present invention comprises a monomer (a) represented by the following general formula (1) and a monomer (b) represented by the following general formula (2) and / or the following general formula (3 ) is a lubricating oil composition containing a copolymer (A) having a monomer (c) represented by ) as an essential constituent monomer, and an ester oil (B).

[In the formula (1), A ¹ is a monovalent radically polymerizable group, and -X ¹ -, -X ² - and -X ³ - are each independently a group represented by -O- or -NH- wherein R ¹ is an alkylene group having 1 to 4 carbon atoms, each R ² is independently an alkylene group having 2 to 20 carbon atoms, and when there are a plurality of R ² may be the same or different, R ³ is a hydrogen atom, an alkyl group having 1 to 44 carbon atoms, an acyl group having 2 to 45 carbon atoms, a phenyl group or a benzoyl group optionally substituted with an alkyl group having 1 to 44 carbon atoms, and p is 1 Integer from ~100. ]

[In the formula ( ² ), R ⁴ is a hydrogen atom or a methyl group; -X ⁴ - is a group represented by -O- or -NH-; is an alkyl group of ]

[wherein R ⁶ is a hydrogen atom or a methyl group; -X ⁵ - is a group represented by -O-, -O(AO) _m - or -NH-, and A has 2 carbon atoms; to 4 alkylene groups, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different; R ⁷ is an isobutylene group and/or a 1,2-butylene group; A residue obtained by removing one hydrogen atom from a hydrocarbon polymer having 43 or more carbon atoms as an essential structural unit; q is the number of 0 or 1; ]

Each of the copolymer (A) and the ester oil (B) may be used alone, or two or more thereof may be used in combination.
In the present invention, by combining the copolymer (A) and the ester oil (B), the heat transfer coefficient at 40 ° C. is 2.10 W / (m ² /K) or more}, and the MTM (mini-traction) coefficient of friction at low speed (measured under the conditions described later, the same below) (100°C, speed: 10 mm/s) is as high as 0.070 or more, which is good for power transmission characteristics. It has been found that the MTM friction coefficient (100° C., speed: 100 mm/s) can be rapidly reduced to 0.055 or less at high speeds, and high lubricity can be achieved.

<Copolymer (A)>
In the present invention, the copolymer (A) uses the monomer (a) represented by the general formula (1) as an essential constituent monomer.
A1 in the general formula ( ¹ ) is a monovalent radically polymerizable group, specifically a vinyl group, a (meth)acryloyl group, or the like.
From the viewpoint of lubricity, A ¹ is preferably a vinyl group or a (meth)acryloyl group, more preferably a (meth)acryloyl group.

In general formula (1), -X ¹ -, -X ² - and -X ³ - are each independently a group represented by -O- or -NH-.
These -X ¹ -, -X ² - and -X ³ - are preferably -O- from the viewpoint of lubricity.

R ¹ in general formula (1) is an alkylene group having 1 to 4 carbon atoms.
Examples of the alkylene group having 1 to 4 carbon atoms include methylene group, ethylene group, 1,2- and 1,3-propylene group, and 1,2-, 1,3- and 1,4-butylene group. . Among these, from the viewpoint of lubricity, ethylene group, 1,2-propylene group and 1,3-propylene group are preferable, and ethylene group is more preferable.

p in the general formula (1) is an integer of 1 to 100, and is preferably 1 to 1 from the viewpoint of friction reduction at high speed and solubility in base oil (ester oil (B), etc., the same applies hereinafter). It is an integer of 70, more preferably an integer of 1-40, particularly preferably an integer of 1-20.
When p is 2 or more, a plurality of (-C(=O)-R ² -X ³ -) may be the same or different.

R ² in general formula (1) is an alkylene group having 2 to 20 carbon atoms, and when there are a plurality of R ² s, they may be the same or different.
Examples of alkylene groups having 2 to 20 carbon atoms include ethylene group, 1,2- or 1,3-propylene group, isobutylene group, 1,2-, 1,3- or 1,4-butylene group and isopentylene group. , 1,2-, 1,3-, 1,4- or 1,5-pentylene group, isohexylene group, 1,2-, 1,3-, 1,4-, 1,5- or 1,6- hexylene group, isoheptylene group, 1,2-, 1,3-, 1,4-, 1,5-, 1,6- or 1,7-heptylene group, isooctylene, 1,8-octylene group, isononylene group, 1,9-nonylene group, isodecylene group, 1,10-decylene group, isoundecylene group, 1,11-undecylene group, isododecylene group, 1,12-dodecylene group, isotridecylene group, 1,13-tridecylene group, isotetra Decylene group, 1,14-tetradecylene group, isopentadecylene group, 1,15-pentadecylene group, isohexadecylene group, 1,16-hexadecylene group, isoheptadecylene group, 1,17-heptadecylene group, Examples include an isooctadecylen group, a 1,18-isooctadecylene group, an isononadecylene group, a 1,19-isononadecylene group, an isoeicosilene group, and a 1,20-eicosilene group.
R ² is preferably an alkylene group having 2 to 17 carbon atoms, more preferably an alkylene group having 2 to 15 carbon atoms, particularly preferably an alkylene group having 2 to 13 carbon atoms, from the viewpoint of reducing friction at high speed. An alkylene group having 2 to 10 carbon atoms is most preferred.

R ³ in general formula (1) is a hydrogen atom, an alkyl group having 1 to 44 carbon atoms, an acyl group having 2 to 45 carbon atoms, a phenyl group optionally substituted with an alkyl group having 1 to 44 carbon atoms, or benzoyl is the base.

The alkyl group having 1 to 44 carbon atoms includes linear or branched alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec -butyl group, tert-butyl group, n-pentyl group, isopentyl group, n-hexyl group, isohexyl group, n-heptyl group, isoheptyl group, n-octyl group, 2-ethylhexyl group, isooctyl group, n-nonyl group , isononyl group, n-decyl group, isodecyl group, n-undecyl group, isoundecyl group, n-dodecyl group, isododecyl group, n-tridecyl group, isotridecyl group, n-tetradecyl group, 2-ethyldodecyl group, n-pentadecyl group, 2-methyltetradecyl group, n-hexadecyl group, isohexadecyl group, n-heptadecyl group, isoheptadecyl group, 2-ethylpentadecyl group, 2-octylnonyl group, 2-(3-methylhexyl)-7 -methyl-nonyl group, n-octadecyl group, isooctadecyl group, 2-hexylundecyl group, 2-ethylheptadecyl group, 1-hexyltridecyl group, n-icosyl group, 2-octylundecyl group, isoicosyl group , 1-undecyldodecyl group, 1-octylpentadecyl group, 2-decyltridecyl group, n-tetraicosyl group, 2-decyltetradecyl group, 2-dodecylpentadecyl group, 2-heptylicosyl group, 2-dodecylhexadecyl group , n-triacontyl group, 2-tetradecyloctadecyl group, n-hexatriacontyl group, n-tetracontyl group, 2-ethyltetracontyl group and olefin [e.g. propylene oligomer (2-14mer), ethylene/propylene Oligomers (2-20mers), isobutene oligomers (2-10mers), etc.] and residues obtained by removing hydroxyl groups from oxoalcohols.

Acyl groups include acyl groups derived from carboxylic acids having 2 to 45 carbon atoms and having alkyl groups having 1 to 44 carbon atoms, such as acetyl, propionyl, butanoyl, pentanoyl, and hexanoyl groups. , heptanoyl group, octanoyl group, nonanoyl group, decanoyl group, lauryloyl group, myristoyl group, palmitoyl group and the like.

Examples of the phenyl group or benzoyl group optionally substituted with an alkyl group having 1 to 44 carbon atoms include a phenyl group, a benzoyl group, and an alkyl group having 1 to 44 carbon atoms in which some or all of the hydrogen atoms of the phenyl group a group substituted with a group (such as a tolyl group), a group in which some or all of the hydrogen atoms of a benzoyl group are substituted with an alkyl group having 1 to 44 carbon atoms, and the like.

Among these R3 ^, from the viewpoint of reducing friction at high speed, it is substituted with a hydrogen atom, an alkyl group with 1 to 12 carbon atoms, an acyl group with 2 to 13 carbon atoms, or an alkyl group with 1 to 12 carbon atoms. A phenyl group or a benzoyl group is preferred, and a hydrogen atom and an acyl group having 4 to 12 carbon atoms are more preferred.

A structural unit derived from the monomer (a) (a structure in which the radically polymerizable carbon-carbon double bond of the monomer (a) reacts to form a single bond) is soluble in the base oil. Therefore, those having a specific solubility parameter (hereinafter sometimes abbreviated as SP value) are preferred.
The range of the SP value is preferably 9.0 to 12.5 (cal/cm ³ ) ^1/2 , more preferably 9.3 to 12.3 (cal/cm ³ ) ^1/2 , especially It is preferably 9.5 to 12.0 (cal/cm ³ ) ^1/2 .

Further, when the copolymer (A) uses two or more monomers (a) in combination, the SP value of each of the plurality of monomers constituting (a) is calculated by the above method, It is preferable that the SP value of each monomer (a) is arithmetically averaged based on the weight fraction of the constituent monomer units and satisfies the range of the SP value of the monomer (a).
When the SP value of the structural unit derived from the monomer (a) is within the above range, friction reduction at high speed and solubility in base oil tend to be good.
The SP value in the present invention is the numerical value (atom or functional group (heat of vaporization at 25°C and molar volume of Specifically, from the numerical values of _{Δei and v i described} in Table 1 below, which are parameters of the Fedors method, numerical values corresponding to the types of atoms and atomic groups in the molecular structure are applied to the following formula. can be calculated.
SP value = (ΣΔe _i /Σv _i ) ^1/2

The molecular formula weight or number average molecular weight (hereinafter abbreviated as Mn) of the monomer (a) is preferably 150 to 20,000, more preferably 150 to 10,000, from the viewpoint of reducing friction at high speeds. , particularly preferably 150 to 7,000, most preferably 150 to 4,000.
The Mn of (a), the weight average molecular weight (hereinafter abbreviated as Mw) and Mn of (c), and the Mw and Mn of the copolymer (A) described later are determined by gel permeation chromatography (hereinafter abbreviated as GPC). can be measured under the following conditions.
<Measurement conditions for Mn in (a), Mw and Mn in (c), Mw and Mn in (A)>
Apparatus: "HLC-802A" [manufactured by Tosoh Corporation]
Column: 2 "TSK gel GMH6" [manufactured by Tosoh Corporation] Measurement temperature: 40 ° C.
Sample solution: 0.25% by weight tetrahydrofuran solution Solution injection volume: 100 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]

From the viewpoint of reducing friction at high speeds, the monomer (a) is preferably a lactone adduct (a1) of hydroxyalkyl (meth)acrylate with 1 to 100 moles of lactone (a1) and a monomonomer having 2 to 45 carbon atoms. Carboxylic acid ester (a2-1), (a1) and benzoic acid (part of the hydrogen atoms bonded to the aromatic ring of benzoic acid may be substituted with an alkyl group having 1 to 44 carbon atoms ) (a2-2), etherified product (a2-3) of (a1) with alkyl alcohol having 1 to 44 carbon atoms, lactam 1 to 100 mol adduct of hydroxyalkyl (meth)acrylate (a3) , (a3) and an amidated product (a4) of a monocarboxylic acid having 2 to 45 carbon atoms.
These monomers (a) can be obtained by known production methods.

Examples of the monomer (a) include the following.
1-100 mol lactone adduct of hydroxyalkyl (meth)acrylate (a1):
Hydroxyalkyl (having 1 to 4 carbon atoms in a hydroxyalkyl group) (meth)acrylate {e.g., hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA), etc.} to a lactone (having 3 to 21 carbon atoms, such as β-propio lactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, etc.) obtained by ring-opening addition.
The reaction temperature for the ring-opening addition reaction of lactone to hydroxyalkyl (meth)acrylate is preferably 80° C. to 150° C., more preferably 100° C. to 140° C. from the viewpoint of reaction time. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours. The reaction is mainly carried out in the presence of a catalyst.
The catalyst for the above reaction may be a known catalyst such as p-toluenesulfonic acid, tetrapropyl titanate, stannous octoate and the like. The amount of catalyst used is preferably 0.01 to 5% by mass, more preferably 0.03 to 0.5% by mass, relative to the amount of reaction product. After completion of the ring-opening addition reaction, the catalyst is desirably treated by a method of removing by adsorption/filtration using an adsorbent, a method of neutralizing to deactivate the catalyst, or the like.

Esterified product (a2-1) of (a1) with a monocarboxylic acid having 2 to 45 carbon atoms and (a1) and benzoic acid (a portion of the hydrogen atoms bonded to the aromatic ring of benzoic acid Esterified product (a2-2) with (which may be substituted by an alkyl group of 44):
The reaction temperature for the esterification reaction between (a1) and a carboxylic acid (monocarboxylic acid having 2 to 45 carbon atoms, benzoic acid, etc.) is preferably from the viewpoint of reaction time and prevention of polymerization of (meth)acrylic acid. It is 80°C to 150°C, more preferably 90°C to 130°C. Moreover, in the esterification reaction, the reaction pressure may be reduced for the purpose of removing the generated water. A preferable reaction pressure is preferably 0.007 to 0.095 MPa, more preferably 0.01 to 0.092 MPa from the viewpoint of reaction time and prevention of polymerization. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours. The esterification reaction is desirably carried out in the presence of a catalyst.
The catalyst for the esterification reaction may be a known catalyst such as sulfuric acid and p-toluenesulfonic acid. A solvent may be used in the esterification reaction, and examples of the solvent include non-aqueous solvents having a boiling point of 150° C. or lower, such as cyclohexane and toluene.
Examples of monocarboxylic acids having 2 to 45 carbon atoms include saturated aliphatic monocarboxylic acids (e.g., ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, etc.), unsaturated aliphatic monocarboxylic acids (eg, oleic acid, linoleic acid, linolenic acid, arachidonic acid, docosahexanoic acid, etc.). Among these, saturated aliphatic monocarboxylic acids are preferred, and saturated aliphatic monocarboxylic acids having 2 to 13 carbon atoms are more preferred.

Etherified product (a2-3) of (a1) with alkyl alcohol having 1 to 44 carbon atoms:
(a1) and an alkylating agent having 1 to 44 carbon atoms (alkyl chloride such as methyl chloride, ethyl chloride, propyl chloride, butyl chloride, isopropyl chloride, allyl chloride; methyl bromide, ethyl bromide, propyl bromide, butyl bromide, isopropyl alkyl bromide such as bromide) and an alkali (eg, amine, quaternary ammonium salt, sodium hydroxide, etc.) under general conditions.

1-100 mol lactam adducts of hydroxyalkyl (meth)acrylates (a3):
Hydroxyalkyl (having 1 to 4 carbon atoms in a hydroxyalkyl group) (meth)acrylate {e.g., hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA), etc.} to a lactam (having 3 to 21 carbon atoms, such as β-lactam, γ-lactam, δ-lactam, ε-lactam, etc.) obtained by ring-opening addition.
The reaction temperature for the ring-opening addition reaction of the lactam to the hydroxyalkyl (meth)acrylate is preferably 80°C to 150°C, more preferably 100°C to 140°C, from the viewpoint of the reaction time. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours. The reaction is mainly carried out in the presence of a catalyst.
The catalyst for the above reaction may be a known catalyst such as tetrapropyl titanate and stannous octoate. The amount of catalyst used is preferably 0.01 to 5% by mass, more preferably 0.03 to 0.5% by mass, relative to the amount of reaction product.
After completion of the ring-opening addition reaction, the catalyst is desirably treated by a method of removing by adsorption/filtration using an adsorbent, or a method of inactivating the catalyst by neutralization.

Amidated product (a4) of (a3) and a monocarboxylic acid having 2 to 45 carbon atoms:
The reaction temperature for the amidation reaction between (a3) and a monocarboxylic acid having 2 to 45 carbon atoms is preferably 80° C. to 150° C. from the viewpoint of reaction time and prevention of polymerization of (meth)acrylic acid, More preferably, it is 90°C to 130°C. Also, in the amidation reaction, the reaction pressure may be reduced for the purpose of removing water produced. A preferable reaction pressure is preferably 0.007 to 0.095 MPa, more preferably 0.01 to 0.092 MPa from the viewpoint of reaction time and prevention of polymerization. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours.
Examples of monocarboxylic acids having 2 to 45 carbon atoms include saturated aliphatic monocarboxylic acids (e.g., ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, etc.), unsaturated aliphatic monocarboxylic acids (eg, oleic acid, linoleic acid, linolenic acid, arachidonic acid, docosahexanoic acid, etc.). Among these, saturated aliphatic monocarboxylic acids are preferred, and saturated aliphatic monocarboxylic acids having 2 to 13 carbon atoms are more preferred.

Of the monomers (a), from the viewpoint of reducing friction at high speeds, lactone 1 to 100 mol adducts (a1) and (a1) of hydroxyalkyl (meth)acrylates and monomers having 2 to 45 carbon atoms are preferred. Esterified product (a2-1) with carboxylic acid, more preferably (a1), and particularly preferably (a1) having 1 to 20 moles of added lactone.

In the spectrum obtained by nuclear magnetic resonance spectroscopy ( ¹³ C-NMR), the monomer (a) has a total area ratio (M1) of the peaks between the chemical shifts of 170 and 180 ppm with respect to the total area of all peaks, and The ratio (M1/M2) to the total area ratio (M2) of the peaks between chemical shifts of 160-170 ppm with respect to the total area is preferably 0.01 or more, more preferably 0.02 or more. It is more preferably 0.03 or more, particularly preferably 0.04 or more, and most preferably 0.05 or more. Also, the ratio (M1/M2) is preferably 200 or less, more preferably 180 or less, particularly preferably 150 or less, and most preferably 130 or less. When the ratio (M1/M2) is 0.01 or more, lubricity and fuel efficiency tend to be good, and when it is 200 or less, compatibility with the ester oil (B) is good and storage stability is obtained. tend to be better.

It should be noted that the total area of peaks between chemical shifts 170-180 ppm (M1) relative to the total area of all peaks is the specific carbonyl of (meth)acrylate relative to the total integrated intensity of all carbons measured by ¹³ C-NMR. Means the fraction of the integrated intensity derived from the structure. The total area of the peaks between chemical shifts 160-170 ppm (M2) relative to the total area of all peaks is the sum of the integrated intensities of all carbons measured by ¹³ C-NMR for the specific carbonyl structure of the (meth)acrylate. It means the fraction of the integrated intensity derived.

The ratio (M1/M2) refers to the specific carbonyl structure ratio of (meth)acrylate, but other methods may be used as long as equivalent results are obtained. In the ¹³ C-NMR measurement, a sample diluted by adding 2 ml of deuterated chloroform to 0.1 g of the sample was used, the measurement temperature was room temperature, the resonance frequency was 100 MHz, and the measurement method was decoupling with a reverse gate. measured using the method

According to the above analysis,
(a) the sum of integrated intensities for chemical shifts 160-180 ppm (sum of integrated intensities attributed to total carbon in hydrocarbons), and (b) the sum of integrated intensities of chemical shifts 170-180 ppm (resulting from specific carbonyl structures sum of integrated intensities)
(c) the sum of the integrated intensities of the chemical shift 160-170 ppm (the sum of the integrated intensities attributed to the specific carbonyl structure)
are measured respectively, and the ratio (%) of (b) when (a) is taken as 100% is calculated as M1. Similarly, the ratio (%) of (c) when (a) is 100% is calculated and defined as M2.

The copolymer (A) in the present invention comprises the monomer (b) represented by the general formula (2) and/or the monomer (c) represented by the general formula (3). Including as a body.

In the monomer (b), —X ⁴ — in general formula (2) is a group represented by —O— or NH—, preferably —O— from the viewpoint of reducing friction at high speeds. .

In the monomer (b), ^R4 in general formula (2) is a hydrogen atom or a methyl group, preferably a methyl group from the viewpoint of reducing friction at high speeds.

In monomer (b), R ⁵ in general formula (2) is a linear or branched alkyl group having 5 to 44 carbon atoms. Specifically, n-pentyl group, isopentyl group, n-hexyl group, isohexyl group, n-heptyl group, isoheptyl group, n-octyl group, 2-ethylhexyl group, isooctyl group, n-nonyl group, isononyl group, n-decyl group, isodecyl group, n-undecyl group, isoundecyl group, n-dodecyl group, isododecyl group, n-tridecyl group, isotridecyl group, n-tetradecyl group, 2-ethyldodecyl group, n-pentadecyl group, 2- methyltetradecyl group, n-hexadecyl group, isohexadecyl group, n-heptadecyl group, isoheptadecyl group, 2-ethylpentadecyl group, 2-octylnonyl group, 2-(3-methylhexyl)-7-methyl-nonyl group, n-octadecyl group, isooctadecyl group, 2-hexylundecyl group, 2-ethylheptadecyl group, 1-hexyltridecyl group, n-icosyl group, 2-octylundecyl group, isoicosyl group, 1-un decyldodecyl group, 1-octylpentadecyl group, 2-decyltridecyl group, n-tetraicosyl group, 2-decyltetradecyl group, 2-dodecylpentadecyl group, 2-heptylicosyl group, 2-dodecylhexadecyl group, n-triacontyl group, 2-tetradecyloctadecyl group, n-hexatriacontyl group, n-tetracontyl group, 2-ethyltetracontyl group and olefin [e.g. propylene oligomer (2-14mer), ethylene/propylene oligomer (2- 20-mer) and isobutene oligomers (2- to 10-mers, etc.)], and the like.

Of R ⁵ , from the viewpoint of solubility in the base oil, preferred is a linear or branched alkyl group having 10 to 34 carbon atoms, and more preferred is a linear or branched carbon an alkyl group having a number of 12 to 32, particularly preferably a linear or branched alkyl group having 16 to 32 carbon atoms, most preferably a linear alkyl group having 16 to 22 carbon atoms, and a branched alkyl group having 18 to 32 carbon atoms.

The SP value of the structural unit derived from the monomer (b) (the structure in which the carbon-carbon double bond of the monomer (b) reacts to become a single bond) is determined from the viewpoint of solubility in the base oil. , preferably 7.0 to 9.5 (cal/cm ³ ) ^1/2 , more preferably 7.3 to 9.2 (cal/cm ³ ) ^1/2 .

In the monomer (c), R ⁶ in general formula (3) is a hydrogen atom or a methyl group, preferably a methyl group from the viewpoint of reducing friction at high speeds.

In monomer (c), -X ⁵ - in general formula (3) is a group represented by -O-, -O(AO) _m - or -NH-.
A is an alkylene group having 2 to 4 carbon atoms.
Examples of the alkylene group having 2 to 4 carbon atoms include ethylene group, 1,2- or 1,3-propylene group, and 1,2-, 1,3- or 1,4-butylene group.
m is an integer of 1 to 10, preferably an integer of 1 to 4, more preferably an integer of 1 to 2, from the viewpoint of solubility in the base oil.
When m is 2 or more, A may be the same or different, and the (AO) _m portion may be a random bond or a block bond.
-X ⁵ - is preferably a group represented by -O- and -O(AO) _m -, more preferably -O- and -O(CH ₂ CH ₂ O) _m -, from the viewpoint of lubricity. is a group represented by

In the monomer (c), q in the general formula (3) is 0 or 1, preferably 0 from the viewpoint of solubility in the base oil.

In the monomer (c), R ⁷ in the general formula (3) is a hydrocarbon polymer having 43 or more carbon atoms containing an isobutylene group and/or a 1,2-butylene group as a structural unit, with one hydrogen atom removed. is a residue.
The isobutylene group is a group represented by —CH ₂ C(CH ₃ ) ₂ — or —C(CH ₃ ) ₂ CH ₂ —, and the 1,2-butylene group is —CH ₂ CH(CH ₂ CH ₃ )— or a group represented by —CH(CH ₂ CH ₃ )CH ₂ —.
Examples of hydrocarbon polymers having isobutylene groups and/or 1,2-butylene groups as constituent units include polymers using isobutene and 1-butene as constituent monomers (unsaturated hydrocarbons (x)), and 1 ,3-butadiene is polymerized, and the double bond of the 1,2-adduct is hydrogenated.
In addition to isobutene, 1-butene and 1,3-butadiene, the hydrocarbon polymer may contain one or more of the following (1) to (3) as unsaturated hydrocarbons (x) as constituent monomers. good.
(1) Aliphatic unsaturated hydrocarbons [olefins having 2 to 36 carbon atoms (e.g., ethylene, propylene, 2-butene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, triacocene, hexatriacosene, etc.) and carbon number 4 to 36 dienes (e.g., isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, etc.), etc.]
(2) alicyclic unsaturated hydrocarbons [e.g. cyclohexene, (di)cyclopentadiene, pinene, limonene, indene, vinylcyclohexene and ethylidenebicycloheptene, etc.]
(3) aromatic group-containing unsaturated hydrocarbons (e.g. styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotyl benzene, vinylnaphthalene, divinylbenzene, divinyltoluene, divinylxylene and trivinylbenzene, etc.)
The hydrocarbon polymer composed of these may be a block polymer or a random polymer. Moreover, when the hydrocarbon polymer has double bonds, it may be obtained by hydrogenating a part or all of the double bonds by hydrogenation. In one embodiment, the hydrocarbon polymer in R ⁷ may be a hydrocarbon polymer using only monomers having 4 carbon atoms as constituent monomers, and the monomers having 4 carbon atoms are isobutene, 1 It may be at least one selected from the group consisting of -butene and 1,3-butadiene.

Mn of monomer (c) is preferably 800 to 10,000, more preferably 1,000 to 9,000, still more preferably 1,200 to 8,500. When the Mn of the monomer (c) is 800 or more, the lubricity tends to be good, and when it is 10,000 or less, the copolymerizability with other monomers tends to be good.

The monomer (c) is an esterification reaction between a polymer (Y) containing a hydroxyl group at one end obtained by introducing a hydroxyl group at one end of a hydrocarbon polymer and (meth)acrylic acid, or It can be obtained by transesterification with an alkyl (meth)acrylate (preferably having 1 to 4 carbon atoms) such as methyl (meth)acrylate. In addition, "(meth)acryl" means "acryl and/or methacryl".

Specific examples of the polymer (Y) containing a hydroxyl group at one end include the following (Y1) to (Y4).
Alkylene oxide adduct (Y1): A hydrocarbon polymer obtained by polymerizing an unsaturated hydrocarbon (x) in the presence of an ionic polymerization catalyst (such as a sodium catalyst) is added with an alkylene oxide (such as ethylene oxide and propylene oxide). those obtained by addition (in this case, the monomer (c) is a compound in which -X ⁵ - is -(AO) _m - and q=0 in general formula (3)).
Hydroboride (Y2); a hydroboration reaction product of a hydrocarbon polymer of an unsaturated hydrocarbon (x) having a double bond at one end (for example, those described in U.S. Pat. No. 4,316,973) ) and the like (in this case, the monomer (c) is a compound in which —X ⁵ — is —O— and q=0 in general formula (3)).
Maleic anhydride-ene-aminoalcohol adduct (Y3); a reactant obtained by an ene reaction between a hydrocarbon polymer of an unsaturated hydrocarbon (x) having a double bond at one end and maleic anhydride, Those obtained by imidization with an amino alcohol (in this case, the monomer (c) is a compound in which -X ⁵ - is -O- and q=1 in general formula (3)).
Hydroformyl hydride (Y4); obtained by hydroformylating a hydrocarbon polymer of unsaturated hydrocarbon (x) having a double bond at one end and then hydrogenating it (for example, JP-A-63-175096 (In this case, the monomer (c) is a compound in which —X ⁵ — is —O— and q=0 in general formula (3)).
Among these polymers (Y) containing a hydroxyl group at one end, from the viewpoint of lubricity, alkylene oxide adducts (Y1), hydroborides (Y2) and maleic anhydride-ene-aminoalcohol addition products are preferred. (Y3), more preferably an alkylene oxide adduct (Y1).

Ratio of butadiene among all monomers constituting R ⁷ in general formula (3) (in a hydrocarbon polymer containing an isobutylene group and/or a 1,2-butylene group as a structural unit, 1,3-butadiene weight ratio) is preferably 50% by weight or more, more preferably 75% by weight or more, still more preferably 85% by weight or more, and particularly preferably 90% by weight or more, from the viewpoint of lubricity. .

In the hydrocarbon polymer containing an isobutylene group and/or a 1,2-butylene group as an essential structural unit in the general formula (3), the total amount of the isobutylene group and the 1,2-butylene group is determined from the viewpoint of lubricity. , preferably 30 mol % or more, more preferably 40 mol % or more, still more preferably 50 mol % or more, based on the total number of moles of the structural units of the hydrocarbon polymer.
As a method for increasing the ratio of the total amount of isobutylene groups and 1,2-butylene groups in the hydrocarbon polymer, for example, the following method can be employed. In the case of the above alkylene oxide adduct (Y1), for example, in anionic polymerization using 1,3-butadiene, the reaction temperature is set to the boiling point of 1,3-butadiene (-4.4 ° C.) or less, and the polymerization is started. The ratio of the total amount of isobutylene groups and 1,2-butylene groups in the hydrocarbon polymer can be increased by reducing the amount of the agent introduced relative to 1,3-butadiene. In the case of the above hydroboride (Y2), maleic anhydride-ene-aminoalcohol adduct (Y3) and hydroformyl-hydride (Y4), the degree of polymerization of the hydrocarbon polymer having a double bond at one end is increased. By doing so, the above ratio can be increased.

The total amount of isobutylene groups and 1,2-butylene groups in the hydrocarbon polymer containing isobutylene groups and/or 1,2-butylene groups in general formula (3) as essential structural units is measured by ¹³ C-NMR. be able to. Specifically, for example, when only a monomer having 4 carbon atoms is used, the hydrocarbon polymer is analyzed by ¹³ C-NMR and calculated using the following formula (1). It is possible to determine the total mole % of the isobutylene group and the 1,2-butylene group based on the total number of moles of the constitutional units. In ¹³ C-NMR, the peak derived from the methyl group of the isobutylene group is the integrated value (integral value A) of 30 to 32 ppm, the branched methylene group (-CH ₂ CH (CH ₂ CH ₃ )- of the 1,2-butylene group) Alternatively, a peak derived from —CH(CH ₂ CH ₃ )CH ₂ —) appears at an integral value (integral value B) of 26 to 27 ppm. The total mol % of the isobutylene group and the 1,2-butylene group based on the total number of moles of the structural units of the hydrocarbon polymer is the integrated value of the above peak and the integrated value of the total carbon peak of the hydrocarbon polymer ( It can be obtained from the integrated value C).
Total amount of isobutylene group and 1,2-butylene group (mol%) = 100 x {(integral value A) x 2 + (integral value B) x 4}/(integral value C) (1)

When the hydrocarbon polymer for R ⁷ contains butadiene, or butadiene and ¹ -butene as constituent monomers, butadiene or butadiene and 1 -In the structure derived from butene, the molar ratio of 1,2-adduct and 1,4-adduct (1,2-adduct/1,4-adduct) is lubricating and compatible with other monomers. From the viewpoint of polymerizability, it is preferably 5/95 to 95/5, more preferably 20/80 to 80/20, still more preferably 30/70 to 70/30.

When the hydrocarbon polymer for R ⁷ contains butadiene, or butadiene and ¹ -butene as constituent monomers, butadiene or butadiene and 1 The molar ratio of 1,2-adduct/1,4-adduct in the structure derived from -butene can be measured by ¹ H-NMR, ¹³ C-NMR, Raman spectroscopy, or the like.

The SP value of the structural unit derived from the monomer (c) (the structure in which the carbon-carbon double bond of the (meth)acryloyl group in the monomer (c) reacts to become a single bond) is the base oil ^From the ^viewpoint of ^{solubility in} .

The copolymer (A) in the present invention is a copolymer further comprising, as a constituent monomer, a (meth)acrylic acid alkyl ester (d) in which the alkyl group is a linear alkyl group having 1 to 4 carbon atoms. may

Examples of (meth)acrylic acid alkyl esters (d) in which the alkyl group is a straight-chain alkyl group having 1 to 4 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, and n-propyl (meth)acrylate. and n-butyl (meth)acrylate.
Among (d), from the viewpoint of lubricity, preferred are (meth)acrylic acid esters having a linear alkyl group having 1 to 3 carbon atoms, and more preferred are methyl (meth)acrylate and (meth)acrylate. Ethyl acrylate, particularly preferably methyl (meth)acrylate.

In the present invention, the copolymer (A) is a hydroxyl group-containing monomer other than the monomer (a) from the viewpoint of friction reduction at high speed (especially at 100 ° C., speed: 100 mm / s and 1000 mm / s). It preferably contains the monomer (e) as a constituent monomer.
Specific examples of the hydroxyl group-containing monomer (e) include the following.
A hydroxyl group-containing aromatic monomer (p-hydroxystyrene, etc.), hydroxyalkyl (having 2 to 6 carbon atoms) (meth)acrylate [2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 2-, 3- or 4-hydroxybutyl (meth)acrylate, 2-hydroxyisobutyl (meth)acrylate, etc.], mono- or di-hydroxyalkyl (having 1 to 4 carbon atoms) substituted (meth)acrylamide [N,N- dihydroxymethyl (meth)acrylamide, N,N-dihydroxypropyl (meth)acrylamide, N,N-di-2-hydroxybutyl (meth)acrylamide, etc.], vinyl alcohol, alkenol having 3 to 12 carbon atoms [(meth)allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-octenol and 1-undecenol, etc.], alkene monools or alkenediols having 4 to 12 carbon atoms [1-buten-3-ol, 2-buten-1-ol and 2-butene-1,4-diol, etc.], hydroxyalkyl (1-6 carbon atoms) alkenyl (3-10 carbon atoms) ethers (2-hydroxyethyl propenyl ether, etc.), polyhydric (3-8 hydric) alcohols ( glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, sugars, sucrose, etc.) alkenyl (C3-10) ethers or (meth)acrylates [sucrose (meth)allyl ether, etc.];
Of these, hydroxyalkyl (2 to 6 carbon atoms) (meth)acrylates are preferred, and 2-hydroxyethyl (meth)acrylate is more preferred, from the viewpoint of reducing friction at high speeds.

Copolymer (A) comprises a phosphorus atom-containing monomer (f) and a nitrogen atom-containing monomer (g) (excluding monomer (a), monomer (b) and monomer (c) ), may be a copolymer containing at least one monomer selected from the group consisting of

Examples of the phosphorus atom-containing monomer (f) used in combination with the monomer (a) include the following monomers (f1) to (f2).

Phosphate ester group-containing monomer (f1):
(Meth)acryloyloxy alkyl (C2-C4) phosphate [(meth)acryloyloxyethyl phosphate and (meth)acryloyloxyisopropyl phosphate] and alkenyl phosphate [vinyl phosphate, allyl phosphate, propenyl phosphate, isopropenyl phosphate, butenyl phosphate, pentenyl phosphate, octenyl phosphate, decenyl phosphate, dodecenyl phosphate, etc.] and the like.

Phosphono group-containing monomer (f2):
(Meth)acryloyloxyalkyl (2-4 carbon atoms) phosphonic acid [(meth)acryloyloxyethyl phosphonic acid, etc.] and alkenyl (2-12 carbon atoms) phosphonic acid [vinyl phosphonic acid, allyl phosphonic acid and octenyl phosphonic acid etc.] and the like.

Of the phosphorus atom-containing monomers (f), preferred is (f1), more preferred is (meth)acryloyloxyalkyl (C 2-4) phosphate, and particularly preferred is (meth ) acryloyloxyethyl phosphate.

The nitrogen atom-containing monomer (g) [excluding monomer (a), monomer (b) and monomer (c)] includes the following monomers (g1) to (g4). be done.
Amido group-containing monomer (g1):
(Meth)acrylamide, monoalkylamino (meth)acrylamide [one in which one alkyl group having 1 to 4 carbon atoms is bonded to the nitrogen atom; for example, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N- Isopropyl (meth)acrylamide and Nn- or isobutyl (meth)acrylamide, etc.], monoalkylaminoalkyl (meth)acrylamide [aminoalkyl group in which one alkyl group having 1 to 4 carbon atoms is bonded to the nitrogen atom (carbon number 2 to 6); for example N-methylaminoethyl (meth)acrylamide, N-ethylaminoethyl (meth)acrylamide, N-isopropylamino-n-butyl (meth)acrylamide and Nn- or isobutylamino- n-butyl (meth)acrylamide, etc.], dialkylamino (meth)acrylamide [those in which two alkyl groups having 1 to 4 carbon atoms are bonded to a nitrogen atom; for example, N,N-dimethyl (meth)acrylamide, N,N- diethyl (meth)acrylamide, N,N-diisopropyl (meth)acrylamide and N,N-di-n-butyl (meth)acrylamide], dialkylaminoalkyl (meth)acrylamide [alkyl having 1 to 4 carbon atoms on the nitrogen atom Those having an aminoalkyl group (having 2 to 6 carbon atoms) in which two groups are bonded; for example, N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylamide, N,N-dimethylamino propyl (meth)acrylamide and N,N-di-n-butylaminobutyl (meth)acrylamide, etc.], N-vinylcarboxylic acid amide [N-vinylformamide, N-vinylacetamide, N-vinyl-n- or isopropionyl amide, N-vinylhydroxyacetamide, etc.] and those having a nitrogen atom only in the amide group.

Nitro group-containing monomer (g2):
4-nitrostyrene and the like.

Primary to tertiary amino group-containing monomer (g3):
Primary amino group-containing vinyl monomers {alkenylamines having 3 to 6 carbon atoms [(meth)allylamine, crotylamine, etc.], aminoalkyl (carbon atoms 2 to 6) (meth)acrylates [aminoethyl (meth)acrylate, etc.] }; secondary amino group-containing vinyl monomer {monoalkylaminoalkyl (meth)acrylate [having an aminoalkyl group (2 to 6 carbon atoms) in which one alkyl group having 1 to 6 carbon atoms is bonded to a nitrogen atom ; such as t-butylaminoethyl (meth)acrylate and methylaminoethyl (meth)acrylate], dialkenylamines having 6 to 12 carbon atoms [di(meth)allylamine, etc.]}; tertiary amino group-containing vinyl monomers {Dialkylaminoalkyl (meth)acrylates [those having an aminoalkyl group (having 2 to 6 carbon atoms) in which two alkyl groups having 1 to 6 carbon atoms are bonded to a nitrogen atom; for example, dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylates], alicyclic (meth)acrylates having a nitrogen atom [morpholinoethyl (meth)acrylates], aromatic vinyl monomers [N,N-diphenylaminoethyl (meth)acrylamide, N, N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone and N-vinylthiopyrrolidone, etc.]} and their hydrochlorides, sulfates, phosphates or lower alkyl (C 1-8) monocarboxylic acid (acetic acid, propionic acid, etc.) salts and the like.

Nitrile group-containing monomer (g4):
(Meth)acrylonitrile and the like.

Of the nitrogen atom-containing vinyl monomers (g), preferred are (g1) and (g3), and more preferred are N,N-diphenylaminoethyl (meth)acrylamide and dimethylaminoethyl (meth)acrylamide. , diethylaminoethyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate.

The copolymer (A) may contain the following monomers (h) to (o) as constituent monomers.

Aliphatic hydrocarbon monomer (h):
Alkenes with 2 to 20 carbon atoms (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.) and alkadiene with 4 to 12 carbon atoms (butadiene, isoprene, 1,4-pentadiene, 1 , 6-heptadiene and 1,7-octadiene).

Alicyclic hydrocarbon monomer (i):
cyclohexene, (di)cyclopentadiene, pinene, limonene, vinylcyclohexene, ethylidenebicycloheptene and the like.

Aromatic hydrocarbon-based monomer (j):
Styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, indene, 4 -crotylbenzene and 2-vinylnaphthalene.

Vinyl esters, vinyl ethers, vinyl ketones (k):
Vinyl esters of saturated fatty acids with 2 to 12 carbon atoms (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octanoate, etc.), alkyl, aryl or alkoxyalkyl vinyl ethers with 1 to 12 carbon atoms (methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether) , butyl vinyl ether, 2-ethylhexyl vinyl ether, phenyl vinyl ether, vinyl-2-methoxyethyl ether and vinyl-2-butoxyethyl ether, etc.) and alkyl or aryl vinyl ketones having 1 to 8 carbon atoms (methyl vinyl ketone, ethyl vinyl ketone and phenyl vinyl ketone, etc.).

Epoxy group-containing monomer (l):
glycidyl (meth)acrylate, glycidyl (meth)allyl ether, and the like.

Halogen-containing monomer (m):
Examples include vinyl chloride, vinyl bromide, vinylidene chloride, (meth)allyl chloride, and halogenated styrene (dichlorostyrene, etc.).

Esters of unsaturated polycarboxylic acids (n):
Alkyl, cycloalkyl or aralkyl esters of unsaturated polycarboxylic acids [alkyl diesters with 1 to 8 carbon atoms of unsaturated dicarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.) (dimethyl maleate, dimethyl fumarate, diethyl maleate) and dioctyl maleate)] and the like.

alkoxyalkyl ether monomer (o);
Methoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, methoxyheptyl (meth)acrylate, methoxyhexyl (meth)acrylate, methoxypentyl (meth)acrylate, methoxyoctyl (meth)acrylate, ethoxy ethyl (meth)acrylate, ethoxypropyl (meth)acrylate, ethoxybutyl (meth)acrylate, ethoxyheptyl (meth)acrylate, ethoxyhexyl (meth)acrylate, ethoxypentyl (meth)acrylate, ethoxyoctyl (meth)acrylate, propoxymethyl ( meth)acrylate, propoxyethyl (meth)acrylate, propoxypropyl (meth)acrylate, propoxybutyl (meth)acrylate, propoxyheptyl (meth)acrylate, propoxyhexyl (meth)acrylate, propoxypentyl (meth)acrylate, propoxyoctyl (meth)acrylate ) acrylate, butoxymethyl (meth)acrylate, butoxyethyl (meth)acrylate, butoxypropyl (meth)acrylate, butoxybutyl (meth)acrylate, butoxyheptyl (meth)acrylate, butoxyhexyl (meth)acrylate, butoxypentyl (meth)acrylate acrylate, butoxyoctyl (meth)acrylate, and the like.
Among monomers (o), preferred are methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate and butoxyethyl (meth)acrylate.

The proportion of the monomer (a) constituting the copolymer (A) is preferably 2 to 50% by weight, based on the total weight of the constituent monomers of (A), from the viewpoint of lubricity and viscosity index. , more preferably 5 to 45% by weight, particularly preferably 5 to 40% by weight.
The total proportion of the monomers (b) and (c) constituting (A) is preferably 20 to 97, based on the total weight of the constituent monomers of (A), from the viewpoint of lubricity and viscosity index. % by weight, more preferably 40 to 94% by weight, particularly preferably 50 to 90% by weight.
The ratio of the monomer (a) constituting the copolymer (A) is preferably 2 to 90% by weight, based on the total weight of the constituent monomers of (A), from the viewpoint of reducing friction at high speeds. %, more preferably 5 to 80% by weight, still more preferably 10 to 70% by weight, particularly preferably 15 to 60% by weight, and most preferably 15 to 55% by weight.
From the viewpoint of friction reduction at high speed and solubility in base oil, the total proportion of the monomers (b) and (c) constituting (A) is the total weight of the constituent monomers of (A). 10 to 98% by weight, more preferably 20 to 95% by weight, still more preferably 30 to 90% by weight, particularly preferably 40 to 85% by weight.
The ratio of the monomer (d) constituting (A) is preferably 50% by weight or less based on the total weight of the constituent monomers of (A) from the viewpoint of reducing friction at high speeds, More preferably 45% by weight or less, still more preferably 40% by weight or less, and particularly preferably 10% by weight or less.
The ratio of the monomer (e) constituting (A) is preferably 1.0 to 20.0, based on the total weight of the constituent monomers of (A), from the viewpoint of reducing friction at high speeds. % by weight, more preferably 1.0 to 15.0% by weight, particularly preferably 5.0 to 10.0% by weight.
The total content of (f) to (g) constituting (A) is preferably 20% by weight, based on the total weight of the constituent monomers of (A), from the viewpoint of reducing friction at high speeds. or less, more preferably 1 to 15% by weight, particularly preferably 2 to 10% by weight.
The total content of (h) to (o) constituting (A) is preferably 10% by weight, based on the total weight of the constituent monomers of (A), from the viewpoint of reducing friction at high speeds. or less, more preferably 1 to 7% by weight, particularly preferably 2 to 5% by weight.

The SP value of (A) is preferably 8.5 to 11.5 (cal/cm ³ ) ^1/2 , more preferably 8.7 to 11.0, from the viewpoint of friction reduction and lubricity at high speeds. (cal/cm ³ ) ^1/2 , more preferably 8.9 to 10.5 (cal/cm ³ ) ^1/2 , particularly preferably 9.2 to 10.2 (cal/cm ³ ) ^{1/2 2} .
The SP value of (A) is obtained by using the above SP value calculation method to determine the structural unit derived from each monomer constituting (A) (the vinyl group contained in each monomer constituting (A) is polymerized The SP value of the structure formed into a single bond by the reaction) is calculated, and the arithmetic mean value is obtained based on the weight fraction of each constituent monomer at the time of preparation. For example, when the monomer is methyl methacrylate, the constitutional unit derived from methyl methacrylate has 2 _CH3 , 1 _CH2 , 1 C, and 1 _CO2 as atomic groups. From the following formula, it can be seen that the SP value of the structural unit derived from methyl methacrylate is 9.933 (cal/cm ³ ) ^1/2 . A similar calculation reveals that the SP value of the structural unit derived from ethyl methacrylate is 9.721 (cal/cm ³ ) ^1/2 .
ΣΔe _i =1125×2+1180+350+4300=8080
Σv _i =33.5×2+16.1−19.2+18.0=81.9
δ=(8080/81.9) ^1/2 =9.933 (cal/cm ³ ) ^1/2
When the polymer is a polymer of 50% by weight of methyl methacrylate and 50% by weight of ethyl methacrylate, the SP value of the polymer is the weight fraction of the SP value of the constituent units derived from each monomer as follows. Calculated by arithmetic averaging based on
SP value of polymer = (9.933 × 50 + 9.721 × 50) / 100 = 9.827
The SP value of the polymer (A) can be set within a desired range by appropriately adjusting the monomers and weight fractions used. Specifically, the SP value can be decreased by using a large amount of a monomer with a long alkyl group, and the SP value can be increased by using a large amount of a monomer with a short alkyl group. can do.

Further, when two or more copolymers (A) are used, the weight fraction is calculated based on the SP value of each polymer (A), and the arithmetic average value preferably satisfies the above SP value. .

Mw of (A) is preferably 5,000 to 2,000,000, more preferably 7,000, from the viewpoint of friction reduction at high speed, viscosity index improvement effect and low temperature viscosity of the lubricating oil composition. 1,000,000, more preferably 10,000 to 600,000, particularly preferably 15,000 to 500,000, and most preferably 20,000 to 250,000.

(A) can be obtained by a known production method, specifically a method of solution polymerization of the above monomers in a solvent in the presence of a polymerization catalyst.
Examples of the solvent include toluene, xylene, alkylbenzene having 9 to 10 carbon atoms, methyl ethyl ketone, ethyl acetate, 2-propanol, ester oil and the like.
Polymerization catalysts include azo catalysts (azobisisobutyronitrile, azobisvaleronitrile, etc.), peroxide catalysts (benzoyl peroxide, cumyl peroxide, lauryl peroxide, etc.) and redox catalysts (benzoyl peroxide and a mixture of tertiary amines, etc.). Further, if necessary, a known chain transfer agent (alkylmercaptan having 2 to 20 carbon atoms, etc.) can be used.
The polymerization temperature is preferably 25-140°C, more preferably 50-120°C. In addition to the above solution polymerization, (A) can be obtained by bulk polymerization, emulsion polymerization or suspension polymerization.
When (A) is a copolymer, the form of polymerization may be either a random addition polymer or an alternating copolymer, and may be either a graft copolymer or a block copolymer.

<Ester oil (B)>
The ester oil (B) is not particularly limited as long as it is an ester compound that has a lubricating function and is conventionally used as a lubricating oil. For example, a diester of a dihydric carboxylic acid (x1) and a monohydric alcohol (y1), a diester of a monohydric carboxylic acid (x2) and a dihydric alcohol (y2), a monohydric carboxylic acid (x2) and a monohydric Esterified product with alcohol (y1), esterified product with monohydric carboxylic acid (x1) and trihydric or higher polyhydric alcohol (y3), trihydric or higher polyhydric carboxylic acid (x3) and monohydric alcohol (y1) Esterified products with and the like.
As the ester oil (B), from the viewpoint of cooling properties, a diester of a divalent carboxylic acid (x1) and a monohydric alcohol (y1), a monovalent carboxylic acid (x2) and a dihydric alcohol (y2 ) and esters of monohydric carboxylic acid (x2) and monohydric alcohol (y1).

Examples of the divalent carboxylic acid (x1) include aliphatic dicarboxylic acids having 2 to 24 carbon atoms [linear saturated aliphatic dicarboxylic acids {e.g., ethanedioic acid (oxalic acid), propanedioic acid (malonic acid, ), n-butanedioic acid (succinic acid), n-heptanedioic acid (glutaric acid), n-hexanedioic acid (adipic acid), n-heptanedioic acid, n-octanedioic acid, n-nonanedioic acid ( azelaic acid), n-decanedioic acid (sebacic acid), n-undecanedioic acid, n-dodecanedioic acid, n-tridecanedioic acid, n-tetradecanedioic acid, n-pentadecanedioic acid and n-hexadecanedioic acid, etc. }, branched saturated aliphatic dicarboxylic acid {e.g., 3-methyladipic acid, etc.}, unsaturated aliphatic divalent carboxylic acid {e.g., maleic acid, fumaric acid, etc.}, alicyclic saturated divalent carboxylic acid {e.g., 1,2- or 1,3-cyclopentanedicarboxylic acid, 1,2-, 1,3- or 1,4-cyclohexanedicarboxylic acid, etc.}, aromatic ring-containing divalent having 8 to 24 carbon atoms Carboxylic acid {eg, phthalic acid, isophthalic acid, terephthalic acid, etc.} and the like.
Among these, from the viewpoint of thermal conductivity, aliphatic dicarboxylic acids having 2 to 24 carbon atoms are preferable, more preferably linear saturated aliphatic dicarboxylic acids having 2 to 24 carbon atoms, and particularly preferable. is a linear saturated aliphatic divalent carboxylic acid having 6 to 10 carbon atoms.

The monovalent carboxylic acid (x2) includes aliphatic monovalent carboxylic acids having 2 to 25 carbon atoms [linear saturated aliphatic monovalent carboxylic acids {e.g., acetic acid, propionic acid, n-butanoic acid, n-pentanoic acid, , n-hexanoic acid, n-heptanoic acid, n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, n-dodecanoic acid, n-tridecanoic acid, n-tetradecanoic acid, n-pentadecanoic acid , n-hexadecanoic acid, n-heptadecanoic acid, n-octadecanoic acid, n-nonadecanoic acid, eicosanoic acid, docosanoic acid, tetracosanoic acid, etc.}, branched saturated aliphatic monovalent carboxylic acids having 4 to 25 carbon atoms {for example , isobutyric acid, 2-ethylhexanoic acid, isononanoic acid, isodecanoic acid, isoundecanoic acid, isododecanoic acid, isotridecanic acid, isotetradecanoic acid, isopentadecanoic acid, isohexadecanoic acid, isoheptadecanoic acid, isooctadecanic acid and isononadecanoic acid}, Alicyclic monovalent carboxylic acid {eg, cyclohexanecarboxylic acid, etc.} etc.], aromatic ring-containing monovalent carboxylic acid {eg, benzoic acid etc.}, etc., can be mentioned.
Among these, from the viewpoint of thermal conductivity and lubricity, aliphatic monovalent carboxylic acids having 2 to 25 carbon atoms are preferable, more preferably linear or branched alkyl groups having 1 to 24 carbon atoms. A compound having an alkyl group (straight-chain or branched-chain saturated aliphatic monovalent carboxylic acid), particularly preferably a straight-chain saturated aliphatic monovalent carboxylic acid having an alkyl group of 5 to 14 carbon atoms.

The monohydric alcohol (y1) includes aliphatic monoalcohols having 1 to 24 carbon atoms [linear saturated aliphatic monoalcohols {e.g., n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, , n-undecyl alcohol, n-dodecyl alcohol, n-tridecyl alcohol, n-tetradecyl alcohol, n-pentadecyl alcohol, n-hexadecyl alcohol, n-heptadecyl alcohol, n-octadecyl alcohol, n-nona Decyl alcohol, n-icosanol, n-heneicosanol, n-docosanol and n-tetracosanol, etc.}, branched branched saturated aliphatic monoalcohols {for example, 2-ethylhexanol, isononyl alcohol, isodecyl alcohol, isoundecyl alcohol, isododecyl alcohol, isotridecyl alcohol, isotetradecyl alcohol, isopentadecyl alcohol, isohexadecyl alcohol, isoheptadecyl alcohol, isooctadecyl alcohol and isononadecyl alcohol}, alicyclic monoalcohols {e.g., cyclohexanol, 2-, 3- or 4-t-butylcyclohexanol, menthol, cyclohexaneethanol, 2-, 3- or 4-isopropylcyclohexanol, etc.}, etc.], containing an aromatic ring having 7 to 24 carbon atoms Monoalcohol {eg, benzyl alcohol, etc.} and the like can be mentioned.
Among these, from the viewpoint of thermal conductivity, aliphatic monoalcohols having 1 to 24 carbon atoms are preferable, more preferably compounds having a linear or branched alkyl group having 1 to 24 carbon atoms in the alkyl group (linear or branched saturated aliphatic monoalcohol), particularly preferably a compound having a linear or branched alkyl group having 4 to 16 carbon atoms in the alkyl group (linear or branched saturated aliphatic monoalcohol).

The dihydric alcohol (y2) includes aliphatic dihydric alcohols having 2 to 24 carbon atoms [linear saturated aliphatic diols {eg, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1, 5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12 -dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,15-pentadecanediol and 1,16-hexadecanediol, etc.}, branched saturated aliphatic diols {e.g., 2-methyl-1 , 3-propanediol, 2-methyl-1,4-butanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 3-methyl-1,5-pentanediol, 1 ,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, 1,2-decanediol, 1,2-undecanediol, 1,2-dodecanediol, 1,2-tridecanediol, 1 , 2-tetradecanediol, 1,2-pentadecanediol and 1,2-hexadecanediol, etc.}, alicyclic diols {e.g., 1,2-, 1,3- or 1,4-cyclohexanediol, etc.}, etc.], Examples thereof include aromatic ring-containing dihydric alcohols having 8 to 24 carbon atoms {eg, ethylene oxide adducts of dihydroxybenzene, etc.}.
Among these, from the viewpoint of heat transfer coefficient, aliphatic dihydric alcohols having 2 to 24 carbon atoms are preferable, linear saturated aliphatic diols having 2 to 24 carbon atoms are more preferable, and 4 carbon atoms are particularly preferable. ˜12 linear or branched saturated aliphatic diols.

The SP value of the ester oil (B) is preferably 8.1 to 10.1 (cal/cm ³ ) ^1/2 , more preferably 8.1 to 10.1 (cal/cm 3 ) 1/2 from the viewpoints of cooling performance, lubricity and solubility of (A). It is 2 to 9.5 (cal/cm ³ ) ^1/2 , and particularly preferably 8.4 to 9.2 (cal/cm ³ ) ^1/2 .
When two or more kinds of ester oils (B) are used, it is preferable that the SP value and weight fraction of each ester oil are calculated and the arithmetic average value satisfies the above SP value.

The kinematic viscosity of the ester oil (B) at 40° C. (measured according to JIS-K2283) (unit: mm ² /s, abbreviated hereinafter) is preferably 3 to 30 from the viewpoint of cooling performance and lubricity. Preferably it is 3-15.
The kinematic viscosity at 40° C. of the ester oil (B) can be adjusted by adjusting the carbon number and branching degree of the carboxylic acid and alcohol when synthesizing the ester oil (B). The kinematic viscosity tends to be high, and the kinematic viscosity tends to be low when the one with a small number of carbon atoms is used. Further, those with a small degree of branching tend to have high kinematic viscosity, and those with a large degree of branching tend to have low kinematic viscosity.
As the ester oil (B), an ester compound having 10 to 40 carbon atoms is preferred, and an ester compound having 15 to 26 carbon atoms is more preferred, from the viewpoint of lubricity and cooling properties.
From the viewpoint of lubricity and cooling properties, the ester oil (B) is a mixture of a linear saturated aliphatic dicarboxylic acid having 6 to 10 carbon atoms and a branched saturated aliphatic monoalcohol having 4 to 16 carbon atoms. Diester products, diester products of linear saturated aliphatic monocarboxylic acids having 5 to 14 carbon atoms and branched saturated aliphatic diols having 4 to 12 carbon atoms, and alkyl groups having 5 to 14 carbon atoms An ester of a linear saturated aliphatic monocarboxylic acid and a branched saturated aliphatic monoalcohol having 4 to 16 carbon atoms is preferred.
From the viewpoint of lubricity and cooling properties, the ester oil (B) preferably has 2 to 6 methyl groups, more preferably 3 to 4 methyl groups.
Compounds having three methyl groups include, for example, diesters of 3-methyl-1,5-pentanediol and linear saturated aliphatic monovalent carboxylic acid.
Compounds having four methyl groups include, for example, diesters of 2-ethylhexyl alcohol and linear saturated aliphatic dicarboxylic acid.

As the ester oil (B), specifically, a diester of a dihydric carboxylic acid (x1) and a monohydric alcohol (y1) {for example, bis(2-ethylhexyl) sebacate (100° C. kinematic viscosity: 3.19, 40°C kinematic viscosity: 11.3), bis(2-ethylhexyl) dodecanedioate (100°C kinematic viscosity: 3.7, 40°C kinematic viscosity: 13.7), ditridecyldodecanedioic acid (100°C kinematic viscosity: 5.1, 40°C kinematic viscosity: 24.0), bis(n-octyl) adipate (100°C kinematic viscosity: 2.6, 40°C kinematic viscosity: 8.2), bis(2-ethyl to xyl) (100°C kinematic viscosity: 2.4, 40°C kinematic viscosity: 7.8), bis(2-ethylhexyl) azelate (100°C kinematic viscosity: 3.0, 40°C kinematic viscosity: 10.4), 2-ethylhexyl-n-octyl azelate (100°C kinematic viscosity: 3.1, 40°C kinematic viscosity: 10.8), 2-ethylhexyl-n-octyl sebacate (100°C kinematic viscosity: 3.6, 40° C. kinematic viscosity: 11.7), etc.}, a diester of a monohydric carboxylic acid (x2) and a dihydric alcohol (y2) {for example, bis(pentanoic acid)-3-methyl-1,5-pentanediyl (100° C. Kinematic viscosity: 1.5, 40°C kinematic viscosity: 3.7), bis(octanoic acid)-3-methyl-1,5-pentanediyl (100°C kinematic viscosity: 2.41, 40°C kinematic viscosity: 7.4 ), bis(nonanoic acid)-3-methyl-1,5-pentanediyl (100°C kinematic viscosity: 2.7, 40°C kinematic viscosity: 8.9), bis(decanoic acid)-3-methyl-1,5 -Pentanediyl (100°C kinematic viscosity: 3.2, 40°C kinematic viscosity: 10.7), diester of neopentyl glycol and isooctanoic acid (100°C kinematic viscosity: 2.9, 40°C kinematic viscosity: 11.4) , a diester of neopentyl glycol and 2-ethylhexanoic acid (100 ° C. kinematic viscosity: 2.0, 40 ° C. kinematic viscosity: 7.5) etc.}, a monohydric alcohol (y1) and a monovalent carboxylic acid (x2) {for example, isooctanol oleate (100°C kinematic viscosity: 2.7, 40°C kinematic viscosity: 8.3), etc.} and the like.

The kinematic viscosity of the ester oil (B) at 100° C. (as measured by JIS-K2283) is preferably 1 to 15 mm ² /s, more preferably 2 to 5 mm ² /s, from the viewpoint of cooling performance and lubricity. , from the viewpoint of viscosity index, it is particularly preferably 2.4 to 3.2 mm ² /s.
The viscosity index (measured according to JIS-K2283) of the ester oil (B) is preferably 90 or more, more preferably 100 or more, from the viewpoint of lubricity.

The cloud point (as measured by JIS-K2269) of the ester oil (B) is preferably -5°C or lower, more preferably -15°C or lower. When the cloud point of the base oil is within this range, the low-temperature viscosity of the lubricating oil composition is favorable.

<Lubricating oil composition>
The lubricating oil composition of the present invention contains the copolymer (A) and the ester oil (B).
The weight ratio (A/B) of the copolymer (A) and the ester oil (B) in the lubricating oil composition is from 0.001 to 0.001 from the viewpoint of friction reduction at high speed, cooling performance and lubricity. 0.43 is preferred, and 0.001 to 0.11 is more preferred.
The content of the copolymer (A) in the lubricating oil composition is 0.1 to 30% by weight, based on the weight of the lubricating oil composition, from the viewpoint of friction reduction at high speed, cooling performance and lubricity. is preferred, and more preferably 0.1 to 10% by weight.
The content of the ester oil (B) in the lubricating oil composition is preferably 40% by weight or more, more preferably 60% by weight or more, based on the weight of the lubricating oil composition, from the viewpoint of cooling performance. It is preferably 70 to 99.9% by weight, particularly preferably 90.0 to 99.9% by weight.

The lubricating oil composition of the present invention may contain a base oil other than the ester oil (B).
Base oils include mineral oils (solvent-refined oils, paraffin oils, high viscosity index oils containing isoparaffins, high viscosity index oils and naphthenic oils obtained by hydrocracking isoparaffins, etc.), synthetic lubricating oils [hydrocarbon synthetic lubricating oils (poly-α-olefin synthetic lubricating oil, etc.) and the like.
As the base oil other than the ester oil (B), a mineral oil is preferable from the viewpoint of the insulating properties and the solubility of (A).
From the viewpoint of cooling performance, the base oil other than the ester oil (B) preferably has a kinematic viscosity at 40° C. of 6 to 20 mm ² /s, more preferably 6 to 15 mm ² /s.
From the viewpoint of lubricity, the base oil other than the ester oil (B) preferably has a 100° C. kinematic viscosity of 1 to 6 mm ² /s, more preferably 2 to 5 mm ² /s.
The content of the base oil other than the ester oil (B) in the lubricating oil composition is preferably 80% by weight or less, based on the weight of the lubricating oil composition, from the viewpoint of cooling properties, insulating properties and thermal conductivity, It is more preferably 50% by weight or less, still more preferably 30% by weight or less.

The absolute value of the difference between the SP value of the copolymer (A) and the SP value of the ester oil (B) is preferably 3.4 (cal/cm ³ ) ^1/2 or less from the viewpoint of friction reduction and solubility. , more preferably 2.3 (cal/cm ³ ) ^1/2 or less, and particularly preferably 1.8 (cal/cm ³ ) ^1/2 or less.
In addition, when two or more types of copolymer (A) and ester oil (B) are used in combination, the SP value and weight fraction of (A) are calculated, and the arithmetic average value and the value of (B) It is preferable that the SP value and the weight fraction are calculated, and the difference from the arithmetic average value satisfies the above range.

The absolute value of the difference between the SP value of the structural unit derived from the monomer (a) in the monomers constituting the copolymer (A) and the SP value of the ester oil (B) is the friction at high speed. From the viewpoint of reduction and solubility in base oil, the upper limit is preferably 4.4 (cal/cm ³ ) ^1/2 or less, more preferably 4.1 (cal/cm ³ ) ^1/2 or less, especially It is preferably 3.6 (cal/cm ³ ) ^1/2 or less, and the lower limit is preferably 0.3 (cal/cm ³ ) ^1/2 or more, more preferably 0.9 (cal/cm ³ ) is ^1/2 or more. Preferred ranges are, for example, 0.3 to 4.4 (cal/cm ³ ) ^1/2 , 0.9 to 4.4 (cal/cm ³ ) ^1/2 and the like.
In addition, when the copolymer (A) has structural units derived from multiple types of monomers (a), or when two or more types of ester oils (B) are used in combination, each based on the weight fraction It is preferable that the difference from the arithmetic mean value satisfies the above range.

The number of carbon atoms (N1) of the alkyl group of the monohydric alcohol (y1) constituting the ester oil (B) or the alkyl group of the monohydric carboxylic acid (x2) and the monomer constituting the copolymer (A) The ratio (N1/N2) to the carbon number (N2) of R ⁵ in the body (b) or R ⁷ in the monomer (c) is 0.01 to 4 from the viewpoint of solubility in base oil. 0.80 is preferred, more preferably 0.01 to 1.33.

The thermal conductivity of the lubricating oil composition at 25 ° C. (measured with a thermal property meter under the conditions described later) is preferably 0.14 to 0.16 W / (m K), more preferably 0 from the viewpoint of cooling performance. 0.15 to 0.16 W/(m·K).
The heat transfer coefficient of the lubricating oil composition at 80° C. (calculated under the conditions described later) is preferably 2.35 to 2.80 W/(m ² /K), more preferably 2.45 to 2.70 W/(m ² /K).
The heat transfer coefficient of the lubricating oil composition at 40° C. (calculated under the conditions described later) is preferably 2.10 W/(m ² /K) or more, more preferably 2.10 to 2.45 W, from the viewpoint of cooling performance. /(m ² /K).
From the viewpoint of insulation, the volume resistivity of the lubricating oil composition is preferably 10 ¹⁰ Ω·cm or more, more preferably 10 ¹¹ Ω·cm or more.

The MTM friction coefficient of the lubricating oil composition (measured under the conditions described later, the same applies below) (100 ° C., speed: 10 mm / s) is preferably 0.070 to 0.095, more preferably from the viewpoint of lubricity. is between 0.070 and 0.090.
The MTM friction coefficient (100° C., speed: 100 mm/s) of the lubricating oil composition is preferably 0.055 or less, more preferably 0.030 to 0.055, from the viewpoint of lubricity.
The MTM friction coefficient (100 ° C., speed: 1000 mm / s) of the lubricating oil composition is preferably 0.025 or less, more preferably 0.005 to 0.023, particularly preferably 0.008 from the viewpoint of lubricity. ~0.020.
The ratio (10/100) between the MTM friction coefficient (100 ° C., speed: 10 mm / s) and the MTM friction coefficient (100 ° C., 100 mm / s) of the lubricating oil composition is 1.60 to 1.60 from the viewpoint of lubricity. 2.50 is preferred, and 1.80 to 2.32 is more preferred.
The ratio (10/1000) between the MTM friction coefficient (100 ° C., speed: 10 mm / s) and the MTM friction coefficient (100 ° C., 1000 mm / s) of the lubricating oil composition is 3.0 to 3.0 from the viewpoint of lubricity. 12 is preferred, more preferably 5.5 to 7.5.

The kinematic viscosity of the lubricating oil composition at 40° C. (as measured by JIS-K2283) is preferably 4.0 to 30.0 mm ² /s, more preferably 7.0 to 30.0 mm 2 /s, from the viewpoint of lubricity and cooling performance. 20.0 mm ² /s.
The kinematic viscosity (measured according to JIS-K2283) of the lubricating oil composition at 80° C. is preferably 1.5 to 19.0 mm ² /s, more preferably 3.0 to 8.0 mm ² /s.
The kinematic viscosity of the lubricating oil composition at 100° C. (as measured by JIS-K2283) is preferably 1.0 to 15.0 mm ² /s, more preferably 2.0 to 15.0 mm 2 /s from the viewpoint of lubricity and cooling performance. 5.0 mm ² /s.
The viscosity index (measured according to JIS-K2283) of the lubricating oil composition is preferably 160 or more, more preferably 170 or more, from the viewpoint of lubricity.

The lubricating oil composition of the present invention may further comprise viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, friction and wear modifiers, extreme pressure agents, defoamers, demulsifiers, corrosion inhibitors and rheology agents. It may contain at least one additive selected from the group consisting of point depressants.

(1) Viscosity index improver:
(C1-C7) alkyl (meth)acrylate / (C8-40) linear or branched alkyl (meth)acrylate copolymer, dispersion monomer (amine monomer etc.) / (C1-7) alkyl ( meth) acrylate / (8-40 carbon atoms) linear or branched alkyl (meth) acrylate copolymer, hydroxyl group-containing monomer / (1-7 carbon atoms) alkyl (meth) acrylate / (8-40 carbon atoms) linear Chain or branched alkyl (meth)acrylate copolymer, comb polymer [(C1-7) alkyl (meth)acrylate/(C8-40) linear or branched alkyl (meth)acrylate/polyolefin macromonomer], Ethylene/(C1-C18) alkyl (meth)acrylate copolymer, polyisobutylene, polyalkylstyrene, ethylene/propylene copolymer, styrene/maleic acid ester copolymer, styrene/isoprene hydrogenated copolymer, etc. ;

(2) cleaning agents:
Basic, overbased or neutral metal salts [such as overbased or alkaline earth metal salts of sulfonates (petroleum sulfonates, alkylbenzene sulfonates and alkylnaphthalene sulfonates, etc.)], salicylates, phenates, naphthenates , carbonates, phosphonates and mixtures thereof;
(3) Dispersant:
succinimides (bis- or mono-polybutenyl succinimides), Mannich condensates and borates, etc.;
(4) Antioxidants:
hindered phenols and aromatic secondary amines;
(5) Oiliness improver:
Long-chain fatty acids and their esters (oleic acid and oleic acid esters, etc.), long-chain amines and their amides (oleylamine and oleylamide, etc.), etc.;
(6) Friction and wear modifier:
molybdenum-based and zinc-based compounds (molybdenum dithiophosphate, molybdenum dithiocarbamate and zinc dialkyldithiophosphate, etc.);
(7) extreme pressure agent:
sulfur compounds (mono- or disulfides, sulfoxides and sulfur phosphide compounds), phosphide compounds and chlorine compounds (chlorinated paraffins, etc.);
(8) Defoamer:
Silicon oil, metallic soap, fatty acid ester and phosphate compound, etc.;
(9) Demulsifier:
Quaternary ammonium salts (tetraalkylammonium salts, etc.), sulfated oils and phosphates (polyoxyethylene-containing nonionic surfactant phosphates, etc.), etc.;
(10) Corrosion inhibitor:
nitrogen atom-containing compounds (benzotriazole and 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate, etc.);
(11) Pour point effect agent:
Polyalkyl methacrylate, polyalkyl acrylate, polyalkylstyrene, polyvinyl acetate, and the like.

The lubricating oil composition of the present invention includes gear oils (differential oils, industrial gear oils, etc.), MTF, transmission oils [ATF and belt-CVTF, etc.], traction oils (toroidal-CVTF, etc.), shock absorber oils, power steering It is suitably used for oils, hydraulic fluids (construction machinery hydraulic fluids, industrial hydraulic fluids, etc.), engine oils, and the like. From the viewpoint of easily exhibiting the effect, it is preferably used as a transmission oil, an electric motor oil, or a combination oil for a transmission and an electric motor in an electric vehicle or a hybrid vehicle, and particularly preferably as a transmission oil in an electric vehicle or a hybrid vehicle. It is to be used as a combined oil for machines and electric motors.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.

<Production Example 1> [Production of monomer (a-1)]
2-Hydroxyethyl methacrylate (HEMA) 260.3 was added to a reaction vessel equipped with a temperature controller, a vacuum stirrer, a pressure reducer, a Dimroth condenser, a fractionating tube, a distillate receiving flask, a nitrogen inlet and an outlet. parts by weight (2.0 mol parts), ε-caprolactone 1141.4 parts by weight (10.0 mol parts), hydroquinone monomethyl ether 3.7 parts by weight (0.03 mol parts), butyltris(2-ethylhexanoyloxy ) 0.27 parts by weight of tin was added, and the temperature was raised to 115°C with stirring while passing air. Then, the reaction was carried out at 115° C. for 8 hours, and the distillate was separated. After further cooling to 25° C., the esterification reaction product was confirmed by ¹ H-NMR (yield 98 mol %).
(a-1) is a monomer represented by general formula (1) where A ¹ is a methacryloyl group, R ¹ is an ethylene group, p = 5, R ² = a pentylene group, and R ³ is a hydrogen atom; The SP value of the structural unit derived from a-1) is 10.75.

<Production Example 2> [Production of monomer (a-2)]
A reaction vessel equipped with a temperature controller, a vacuum stirring blade, a pressure reducing device, a Dimroth condenser, a fractionating tube, a distillate receiving flask, a nitrogen inlet and an outlet, 520.8 parts by weight of lauric acid, (a- 1) 711.0 parts by weight, 3.7 parts by weight (0.03 mol part) of hydroquinone monomethyl ether, 300 parts by weight of toluene and 20.7 parts by weight of p-toluenesulfonic acid were added, and the temperature was raised to 115°C while stirring. . Then, an esterification reaction was carried out at 115° C. for 8 hours, and the distillate was separated. After further cooling to 25° C., the esterification reaction product was confirmed by ¹ H-NMR (yield 98 mol %). 200 parts by weight of a 10% by weight sodium hydroxide aqueous solution was added and stirred to sufficiently neutralize p-toluenesulfonic acid. The supernatant was recovered with a separating funnel, and after heating to 120° C., toluene was removed at the same temperature under reduced pressure (0.027 to 0.040 MPa) over 2 hours to obtain (a-2).
(a-2) is a monomer represented by general formula (1) where A ¹ is a methacryloyl group, R ¹ is an ethylene group, p = 5, R ² = a pentylene group, and R ³ is a lauroyl group having 12 carbon atoms. In the body, the SP value of the structural unit derived from (a-2) is 9.68.

<Production Example 3> [Production of monomer (a-3)]
2-hydroxyethyl acrylate (HEA) 232.2 was added to a reaction vessel equipped with a temperature controller, a vacuum stirrer, a pressure reducer, a Dimroth condenser, a fractionating tube, a distillate receiving flask, a nitrogen inlet and an outlet. parts by weight (2.0 mol parts), ε-caprolactone 2282.8 parts by weight (20.0 mol parts), hydroquinone monomethyl ether 3.7 parts by weight (0.03 mol parts), butyltris(2-ethylhexanoyloxy ) 0.27 parts by weight of tin was added, and the temperature was raised to 115°C with stirring while passing air. Then, the reaction was carried out at 115° C. for 8 hours, and the distillate was separated. After further cooling to 25° C., the esterification reaction product was confirmed by ¹ H-NMR (yield 98 mol %).
(a-3) is a monomer represented by general formula (1) where A ¹ is an acryloyl group, R ¹ is an ethylene group, p = 10, R ² = pentylene group, and R ³ is a hydrogen atom; The SP value of the structural unit derived from a-3) is 10.68.

<Production Examples 4 to 24, Comparative Production Examples 1 to 4>
185 parts by weight of ethyl acetate, 100 parts by weight of a blend of various monomers described in Tables 2 to 4, and Table 2 as a chain transfer agent were added to a reaction vessel equipped with a stirrer, a heating/cooling device, a thermometer, and a nitrogen inlet tube. Dodecyl mercaptan and 2,2′-azobis(2-methylbutyronitrile) in the amounts described in 1 to 4 were added, and after nitrogen replacement (gas phase oxygen concentration: 100 ppm), the temperature was raised to 76° C. while stirring under closed conditions. and the polymerization reaction was carried out at the same temperature for 6 hours.
Add 150 parts by weight of the base oil shown in Tables 2 to 4, raise the temperature to 120 to 130° C., and at the same temperature under reduced pressure (0.027 to 0.040 MPa), add unreacted monomers and ethyl acetate for 2 hours. A copolymer solution containing the copolymers (A-1) to (A-12) of the present invention or (A'-1) to (A'-2) for comparison was obtained.

<Comparative Production Examples 5 to 9>
The base oils listed in Table 5 were used directly as solutions.

The various monomers and base oils listed in Tables 2-5 are as described below.
(a-4): HEMA ε-caprolactone 1 mol adduct (a-5): HEMA ε-caprolactone 20 mol adduct (a-6): Terminal butyl ester of HEMA ε-caprolactone 4 mol adduct ( a-7): HEA ε-caprolactone 2 mol adduct (a-8): HEA ε-caprolactone 14 mol adduct (a-9): ε-caprolactone 7 mol adduct of HEA terminal butyl ester (b -1): n-dodecyl methacrylate (b-2): mixture of linear and branched alkyl methacrylates having 12 to 15 carbon atoms (esterified product of Neodol 23 (manufactured by Shell Chemicals) and methacrylic acid)
(b-3): n-hexadecyl methacrylate (b-4): n-octadecyl methacrylate (b-5): 2-decyltetradecyl methacrylate (b-6): 2-dosylhexadecyl methacrylate ( b-7): 2-tetradecyloctadecyl methacrylate (b-8): n-dodecyl acrylate (b-9): n-octadecyl acrylate (c-1): polybutadiene macromonomer (L-1203 manufactured by Kuraray Co., Ltd. [1,2-adduct/1,4-adduct = 45/55] and an ester of methacrylic acid, Mn = 6960)
(c-2): Polybutadiene macromonomer (L-3203 [1,2-adduct/1,4-adduct = 65/35] manufactured by Kuraray Co., Ltd. and esterified product of methacrylic acid, Mn = 6960)
(d-1): methyl methacrylate (d-2): butyl methacrylate (e-1): 2-hydroxyethyl acrylate (e-2): 2-hydroxyethyl methacrylate (e-3): methacrylic acid 2-hydroxyisobutyl (g-1): N,N-dimethylaminoethyl methacrylate (B-1): diester of 3-methyl-1,5-pentanediol and octanoic acid (40° C. kinematic viscosity: 7.38 mm ² /s, 100°C kinematic viscosity: 2.41 mm ² /s, SP value: 8.98
(B-2): Diester of 3-methyl-1,5-pentanediol and nonanoic acid (40° C. kinematic viscosity: 8.93 mm ² /s, 100° C. kinematic viscosity: 2.73 mm ² /s, SP value: 8.95)
(B-3): Diester of 2-ethylhexyl alcohol and adipic acid (40° C. kinematic viscosity: 7.80 mm ² /s, 100° C. kinematic viscosity: 2.40 mm ² /s, SP value: 8.91)
(B-4): Monoester of isooctanol and oleic acid (40° C. kinematic viscosity: 8.20 mm ² /s, 100° C. kinematic viscosity: 2.68 mm ² /s, SP value: 8.61)
(B-5): Diester of 3-methyl-1,5-pentanediol and pentanoic acid (40° C. kinematic viscosity: 3.74 mm ² /s, 100° C. kinematic viscosity: 1.49 mm ² /s, SP value: 9.11)
(B-6): Diester of 2-ethylhexyl alcohol and zebacic acid (40° C. kinematic viscosity: 11.32 mm ² /s, 100° C. kinematic viscosity: 3.19 mm ² /s, SP value: 8.87)
(B-7): Diester of n-octanol and adipic acid (40° C. kinematic viscosity: 8.21 mm ² /s, 100° C. kinematic viscosity: 2.58 mm ² /s, SP value: 9.04)
(B-8): Diester of neopentyl glycol and 2-ethylhexanoic acid (40° C. kinematic viscosity: 7.49 mm ² /s, 100° C. kinematic viscosity: 2.03 mm ² /s, SP value: 8.79)
(C-1): Mineral oil (YUBASE2 manufactured by SK Lubricants, kinematic viscosity at 40°C: 8.65 mm ² /s, kinematic viscosity at 100°C: 2.41 mm ² /s, SP value: 8.20)

<Examples 1 to 21, Comparative Examples 1 to 9>
Using the solutions obtained in Production Examples 4 to 24 and Comparative Production Examples 1 to 9, lubricating oil compositions (V-1) to (V-21) and ( V'-1) to (V'-9) were obtained.
Using the obtained lubricating oil compositions (V-1) to (V-21), (V'-1) to (V'-9), kinematic viscosity at each temperature, viscosity index, thermal conductivity, heat The transmissibility, volume resistivity and MTM friction coefficient were measured by the following methods. In Comparative Examples 5 to 9, the base oils shown in Table 5 were used as they were as lubricating oil compositions (V'-5) to (V'-9).

<Method for calculating the viscosity index of the lubricating oil composition>
The kinematic viscosities at 100°C, 80°C and 40°C were measured by the method of ASTM D 445, and the viscosity index was calculated by the method of ASTM D 2270 from the kinematic viscosities at 100°C and 40°C.

<Measurement of thermal conductivity>
Measurement was performed at room temperature of 25° C. with a single-needle sensor using a thermal property meter KD2pro manufactured by Decagon.

<Method for calculating heat transfer coefficient>
From the kinematic viscosity, thermal conductivity, density and specific heat at constant pressure of the lubricating oil composition at each temperature (40°C or 80°C), the heat transfer coefficient at 40°C and 80°C was calculated using the following formula.

Heat transfer coefficient (W/m ² K) = (density [kg/m ³ ]) ^0.33 × (specific heat at constant pressure [kJ/kgK]) ^0.33 × (thermal conductivity [W/mK]) ^0.67 / (kinematic viscosity [mm ² /s]) ^0.17

<Measurement of volume resistivity>
It was measured at a room temperature of 25° C. in accordance with 24 (volume resistivity test) of JIS C 2101.

<MTM (Mini Traction) Friction Coefficient>
Using an MTM (mini-traction) tester, measurements were made under the following measurement conditions to obtain a Stribeck curve, and the friction coefficient at each speed: 10 mm / s, 100 mm / s, 500 mm / s, 1,000 mm / s was obtained. As shown in Tables 2-5.
Equipment: PCS Instruments MTM-2
Disc: MTM polished disc (standard) (0.01 micron)
Ball: Drilled 3/4 AISI52100 precision steel ball
Speed: 10mm/s to 3,000mm/s
Temperature: 100°C
Sliding/rolling ratio: 50%
Load: 30N

From Tables 2 to 5, the lubricating oil composition of the present invention does not reduce the cooling performance of the ester oil (B) {heat transfer coefficient at 40 ° C. is 2.10 W / (m ² /K) or more}, low The MTM friction coefficient at high speed (100°C, speed: 10 mm/s) is as high as 0.070 or more, and has excellent power transmission characteristics. It can be seen that the lubricity is high.

Since the lubricating oil composition of the present invention has excellent cooling and lubricating properties, it can be toroidal-CVTF, etc.), shock absorber oil, power steering oil, hydraulic oil (construction machine hydraulic oil, industrial hydraulic oil, etc.), engine oil and the like. In particular, it is useful as a transmission oil, an electric motor oil, or a combination oil for a transmission and an electric motor in an electric vehicle or a hybrid vehicle, and is extremely useful as a combination oil for a transmission and an electric motor in an electric vehicle or a hybrid vehicle.

Claims (14)

A monomer (a) represented by the following general formula (1) and a monomer (b) represented by the following general formula (2) and/or a monomer represented by the following general formula (3) ( A lubricating oil composition comprising a copolymer (A) comprising c) as an essential constituent monomer and an ester oil (B).

[In the formula (1), A ¹ is a monovalent radically polymerizable group, and -X ¹ -, -X ² - and -X ³ - are each independently a group represented by -O- or -NH- wherein R ¹ is an alkylene group having 1 to 4 carbon atoms, each R ² is independently an alkylene group having 2 to 20 carbon atoms, and when there are a plurality of R ² may be the same or different, R ³ is a hydrogen atom, an alkyl group having 1 to 44 carbon atoms, an acyl group having 2 to 45 carbon atoms, a phenyl group or a benzoyl group optionally substituted with an alkyl group having 1 to 44 carbon atoms, and p is 1 Integer from ~100. ]

[In the formula ( ² ), R ⁴ is a hydrogen atom or a methyl group; -X ⁴ - is a group represented by -O- or -NH-; is an alkyl group of ]

[wherein R ⁶ is a hydrogen atom or a methyl group; -X ⁵ - is a group represented by -O-, -O(AO) _m - or -NH-, and A has 2 carbon atoms; to 4 alkylene groups, m is an integer of 1 to 10, and when m is 2 or more, A may be the same or different; R ⁷ is an isobutylene group and/or a 1,2-butylene group; A residue obtained by removing one hydrogen atom from a hydrocarbon polymer having 43 or more carbon atoms as an essential structural unit; q is the number of 0 or 1; ] The lubricating oil composition according to claim 1, wherein the copolymer (A) has a weight average molecular weight of 5,000 to 2,000,000. 3. The lubricating oil composition according to claim 1, wherein the copolymer (A) has a solubility parameter of 8.5 to 11.5 (cal/cm ³ ) ^1/2 . The lubricating oil composition according to any one of claims 1 to 3, wherein the ester oil (B) has a kinematic viscosity at 40°C of 3 to 30 mm ² /s. The lubricating oil composition according to any one of claims 1 to 4, wherein the ester oil (B) has a solubility parameter of 8.1 to 10.1 (cal/cm ³ ) ^1/2 . The lubricating oil composition according to any one of claims 1 to 5, wherein the content of the copolymer (A) is 0.1 to 10% by weight based on the weight of the lubricating oil composition. The lubricating oil composition according to any one of claims 1 to 6, wherein the copolymer (A) contains a hydroxyl group-containing monomer (e) other than the monomer (a) as a constituent monomer. Any one of claims 1 to 7, wherein the absolute value of the difference between the solubility parameter of the copolymer (A) and the solubility parameter of the ester oil (B) is 3.4 (cal/cm ³ ) ^1/2 or less. 1. The lubricating oil composition according to claim 1. The ester oil (B) is a diester of a dihydric carboxylic acid (x1) and a monohydric alcohol (y1), a diester of a monohydric carboxylic acid (x2) and a dihydric alcohol (y2), and a monohydric carboxylic acid ( x2) is at least one selected from the group consisting of esters of monohydric alcohols (y1), wherein the monohydric alcohol (y1) is a linear or branched alkyl group having 1 to 24 carbon atoms. wherein the monovalent carboxylic acid (x2) is a compound having a linear or branched alkyl group having 1 to 24 carbon atoms in the alkyl group. 1. The lubricating oil composition according to claim 1. The ester oil (B) is a diester of the dihydric carboxylic acid (x1) and the monohydric alcohol (y1) and/or a diester of the monohydric carboxylic acid (x2) and the dihydric alcohol (y2). Lubricating oil composition according to claim 9 The absolute value of the difference between the solubility parameter of the structural unit derived from the monomer (a) and the solubility parameter of the ester oil (B) is 0.9 to 4.4 (cal/cm ³ ) ^1/2 . The lubricating oil composition according to any one of claims 1-10. The lubricating oil composition according to any one of claims 1 to 11, which is a lubricating oil composition for electric vehicles or hybrid vehicles. 13. The lubricating oil composition according to any one of claims 1 to 12, which is used both as a transmission oil and an electric motor in an electric vehicle or a hybrid vehicle. further selected from the group consisting of viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, friction and wear modifiers, extreme pressure agents, defoamers, demulsifiers, corrosion inhibitors and pour point depressants; The lubricating oil composition according to any one of claims 1 to 13, comprising at least one additive.

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