JP7237753B2 - Lubricating oil composition for internal combustion engine - Google Patents

Description

The present invention relates to a lubricating oil composition for internal combustion engines.

In recent years, lubricating oil compositions with high friction-reducing effects have been desired in various fields. For example, lubricating oil compositions used in engines mounted on automobiles are required to have excellent friction-reducing effects in order to achieve higher fuel efficiency.
In order to obtain a lubricating oil composition with a higher friction-reducing effect, friction modifiers such as molybdenum compounds; ashless friction modifiers such as ester friction modifiers and amine friction modifiers are generally used. It is
In addition to friction modifiers used as additives in lubricating oil compositions, poly(meth)acrylate-based polymers (PMA-based polymers) having a friction-reducing effect have also been investigated.
For example, in Patent Document 1, an alkyl acrylate having an alkyl group having 10 to 18 carbon atoms and a hydroxyalkyl acrylate having a specific structure are used as essential constituent monomers, and the composition ratio of each constituent monomer is specified. and a weight average molecular weight of 2,000 to less than 40,000.
Also, in Patent Document 2, polyalkyl (meth) Polyalkyl (meth)acrylates for improving lubricating oil properties, in acrylates, characterized in that said polyalkyl (meth)acrylates contain repeat units derived from amine derivatives of polar ethylenically unsaturated monomers is disclosed.

JP 2013-124266 A Japanese Patent Application Laid-Open No. 2013-537572

As described above, various friction modifiers have been used and studied to obtain lubricating oil compositions with excellent friction-reducing effects.
By the way, lubricating oil compositions are also used to lubricate various metal members. For example, metal materials containing copper have excellent characteristics such as less fatigue, but have the disadvantage of being easily corroded. Therefore, lubricating oils and their additives are required not only to have the above-mentioned excellent friction-reducing effect, but also to have corrosion resistance to various metal materials.
However, lubricating oil compositions containing molybdenum-based compounds described above do not have sufficient corrosion inhibitory properties against copper. On the other hand, the above-mentioned ashless friction modifiers are good in preventing corrosion of copper, but generally tend to become less effective in reducing friction as the temperature rises.
Similarly, when a PMA-based polymer is used as a friction modifier, there is room for improvement in the friction-reducing effect at high temperatures.
Thus, lubricating oil compositions are required to have both an excellent effect of reducing friction under high temperature conditions and an effect of inhibiting corrosion of copper.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a lubricating oil composition that has an excellent effect of reducing friction even at high temperatures and an excellent effect of suppressing corrosion of copper. be.

As a result of intensive studies, the present inventors have found that a lubricating oil composition containing a base oil (A) and a copolymer (B) having a specific structure can solve the above problems. Each embodiment of the present invention has been completed based on such findings. That is, according to each embodiment of the present invention, the following [1] to [18] are provided.
[1] A base oil (A), a structural unit (a) derived from an alkyl (meth)acrylate having a branched alkyl group having 24 to 75 carbon atoms, and a structural unit (b) represented by the following general formula (b1) A lubricating oil composition containing a copolymer (B) containing

（一般式（ｂ１）中、Ｒ^１は炭素数１～２０の２価の炭化水素基を示し、Ｒ^２はメチル基又は水素原子を示す。ｍ及びｎは、それぞれ独立に、１～１０の整数であり、ｒ及びｓは、それぞれ独立に、１～３０の整数である。）

(In general formula (b1), R ¹ represents a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ² represents a methyl group or a hydrogen atom. m and n each independently represent 1 to 10 is an integer, and r and s are each independently an integer from 1 to 30.)

[2] The component (B) is further selected from the group consisting of amino group-containing monomers, quaternary ammonium base-containing monomers, nitrile group-containing monomers and nitro group-containing monomers. The lubricating oil composition according to [1] above, which is a copolymer containing the structural unit (c) derived from the above monomers.
[3] The content of the structural unit (a) in the component (B) is 40% by mass or more and 60% by mass or less based on 100% by mass of the total amount of the structural units of the component (B), 1] or the lubricating oil composition according to [2].
[4] The lubricating oil composition according to any one of [1] to [3], wherein the component (B) has a mass average molecular weight (Mw) of 2,000 to 200,000.
[5] In addition, metallic detergents, antiwear agents, ashless dispersants, viscosity index improvers, extreme pressure agents, pour point depressants, antioxidants, antifoaming agents, surfactants, demulsifiers, friction The lubricating oil composition according to any one of [1] to [4] above, containing one or more selected from the group consisting of modifiers, oiliness improvers, rust inhibitors and metal deactivators.
[6] The lubricating oil composition according to any one of [1] to [5] above, which has a phosphorus content of 0.10% by mass or less based on the total amount of the lubricating oil composition.
[7] The amino group-containing monomer is (meth)acrylic acid-N,N-dimethylaminoethyl ester, (meth)acrylic acid-N,N-diethylaminoethyl ester and (meth)acrylic acid-N,N - The lubricating oil composition according to any one of [2] to [6] above, which is one or more tertiary amino group-containing monomers selected from the group consisting of -di-t-butylaminoethyl ester.
[8] The above [1] to [7], wherein the component (B) is a copolymer further comprising a hydroxyalkyl acrylate-derived structural unit (d) represented by the following general formula (d1): A lubricating oil composition according to any one of the preceding claims.

（一般式（ｄ１）中、Ｒ^４はメチル基又は水素原子を示し、Ｒ^５は炭素数２～４のアルキレン基を示す。）

(In general formula (d1), R ⁴ represents a methyl group or a hydrogen atom, and R ⁵ represents an alkylene group having 2 to 4 carbon atoms.)

[9] The lubricating oil composition according to any one of [1] to [8], wherein the structural unit (b) is represented by the following general formula (b2).

（一般式（ｂ２）中、Ｒ^２はメチル基又は水素原子を示し、Ｒ^３は炭素数２～８の２価の炭化水素基を表す。）

(In general formula (b2), R ² represents a methyl group or a hydrogen atom, and R ³ represents a divalent hydrocarbon group having 2 to 8 carbon atoms.)

[10] The content of the component (B) is 0.1% by mass or more and 3.0% by mass or less based on the total amount of the lubricating oil composition, according to any one of the above [1] to [9] lubricating oil composition.
[11] The lubricating oil composition according to any one of [1] to [10], wherein the content of molybdenum atoms is 0.05% by mass or less based on the total amount of the lubricating oil composition.
[12] A base oil (A), a structural unit (a) derived from an alkyl (meth)acrylate having a branched alkyl group having 24 to 75 carbon atoms, and a structural unit (b) represented by the following general formula (b1) A method for producing a lubricating oil composition, comprising a copolymer (B) containing

（一般式（ｂ１）中、Ｒ^１は炭素数１～２０の２価の炭化水素基を示し、Ｒ^２はメチル基又は水素原子を示す。ｍ及びｎは、それぞれ独立に、１～１０の整数であり、ｒ及びｓは、それぞれ独立に、１～３０の整数である。）

(In general formula (b1), R ¹ represents a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ² represents a methyl group or a hydrogen atom. m and n each independently represent 1 to 10 is an integer, and r and s are each independently an integer from 1 to 30.)

[13] A method of lubricating a member containing copper, wherein the lubricating oil composition according to any one of [1] to [11] is used.
[14] A method for lubricating a copper-containing member, which comprises using the lubricating oil composition obtained by the method according to [12] above.
[15] A lubricating method characterized by using the lubricating oil composition according to any one of [1] to [11].
[16] A lubricating method, characterized by using the lubricating oil composition obtained by the production method described in [12] above.
[17] An internal combustion engine using the lubricating oil composition according to [1] to [11].
[18] An internal combustion engine using the lubricating oil composition obtained by the production method according to [12].

ADVANTAGE OF THE INVENTION According to this invention, the lubricating oil composition which is excellent in the friction reduction effect also at the time of high temperature, and is excellent in the corrosion inhibitory effect of copper can be provided.

Preferred embodiments of the present invention are described in detail below.
[Lubricating oil composition]
The lubricating oil composition which is one embodiment of the present invention comprises a base oil (A), a structural unit (a) derived from an alkyl (meth)acrylate having a branched alkyl group having 24 to 75 carbon atoms, and the following general formula ( and a copolymer (B) containing the structural unit (b) represented by b1).

（一般式（ｂ１）中、Ｒ^１は炭素数１～２０の２価の炭化水素基を示し、Ｒ^２はメチル基又は水素原子を示す。ｍ及びｎは、それぞれ独立に、１～１０の整数であり、ｒ及びｓは、それぞれ独立に、１～３０の整数である。）

(In general formula (b1), R ¹ represents a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ² represents a methyl group or a hydrogen atom. m and n each independently represent 1 to 10 is an integer, and r and s are each independently an integer from 1 to 30.)

If the lubricating oil composition does not contain the component (B), it becomes difficult to achieve both the effect of reducing friction at high temperatures and the effect of inhibiting corrosion of copper.

Hereinafter, in the present specification, the term "friction reducing effect" means the friction reducing effect of the lubricating oil composition at high temperatures.
Further, in this specification, the term "corrosion inhibitory effect" simply means the copper corrosion inhibitory effect of the lubricating oil composition at high temperatures.
Here, "high temperature" refers to a temperature of 110°C or higher (preferably 130°C or higher, more preferably 135°C or higher).

In addition, in this specification, the lower limit and upper limit values described stepwise for preferred numerical ranges (for example, ranges of content etc.) can be independently combined. For example, the description of the lower limit "preferably 10 or more, more preferably 30 or more, more preferably 40 or more" and the upper limit "preferably 90 or less, more preferably 80 or less, more preferably 70 or less" From the description, as a suitable range, for example, "10 or more and 70 or less", "30 or more and 70 or less", "40 or more and 80 or less". can also Also, from the same description, for example, it is also possible to select a range in which either the lower limit value or the upper limit value is simply defined, such as "40 or more" or "70 or less". Further, for example, "preferably 10 or more and 90 or less, more preferably 30 or more and 80 or less, still more preferably 40 or more and 70 or less", "preferably 10 to 90, more preferably 30 to 80, more preferably 40 to The same applies to the preferred range that can be selected from the description such as "is 70". In addition, in the description of numerical ranges in this specification, for example, the description "10 to 90" is synonymous with "10 or more and 90 or less".
In addition, the term "hydrocarbon group" as used herein means a group composed only of carbon atoms and hydrogen atoms. The "hydrocarbon group" includes an "aliphatic group" composed of a straight or branched chain, an "alicyclic group" having one or more saturated or unsaturated carbon rings having no aromaticity, a benzene ring, etc. includes an "aromatic group" having one or more aromatic rings exhibiting the aromaticity of
In the present specification, "the number of ring-forming carbon atoms" refers to the number of carbon atoms among atoms constituting the ring itself of a compound having a structure in which atoms are cyclically bonded. When the ring is substituted with a substituent, the carbon contained in the substituent is not included in the number of ring-forming carbon atoms.
Further, in the present invention, for example, "(meth)acrylate" refers to both "acrylate" and "methacrylate", and "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid". and other similar terms.
Each component contained in the lubricating oil composition will be described below.

<Base oil (A)>
The base oil (A) (hereinafter also simply referred to as "component (A)") used in the lubricating oil composition is not particularly limited, and conventionally used mineral oils and synthetic oils as base oils for lubricating oils. Any one can be appropriately selected and used from among.
As the mineral oil, for example, the lubricating oil fraction obtained by vacuum distillation of the atmospheric residue obtained by atmospheric distillation of crude oil is subjected to at least one treatment of solvent deasphalting treatment; solvent extraction or hydrocracking. at least one dewaxing treatment of solvent dewaxing or catalytic dewaxing; hydrorefining treatment; and oils produced by decomposing. Among these mineral oils, those which have been hydrorefined are preferred.
Further, as the mineral oil, mineral oil classified into Group 2 of the American Petroleum Institute (API) base oil category and mineral oil classified into Group 3 are more preferable, and mineral oil classified into Group 3 is further preferable. preferable. These mineral oils tend to improve the %C _P and viscosity index, which will be described later.
Synthetic oils include, for example, polybutene; poly-α-olefins such as α-olefin homopolymers and α-olefin copolymers (e.g., ethylene-α-olefin copolymers); polyol esters, dibasic acid esters, phosphorus various esters such as acid esters; various ethers such as polyphenyl ethers; polyglycols; alkylbenzenes; alkylnaphthalenes; GTL base oil; and the like. Among these synthetic oils, poly-α-olefins, esters and GTL base oils are preferred, and combinations of two or more of these oils are also suitable for use as synthetic oils.
In one embodiment of the present invention, as the base oil (A), the mineral oil may be used alone or in combination of two or more. Moreover, the said synthetic oil may be used individually and may be used in combination of 2 or more types. Furthermore, one or more of the mineral oils and one or more of the synthetic oils may be used in combination.
In addition, the content of the base oil (A) is preferably 70% by mass or more, more preferably 75% by mass or more, and still more preferably 80% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition. The content is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 93% by mass or less.

The viscosity of the base oil (A) is not particularly limited, but the kinematic viscosity at 100° C. is preferably 2 mm ² /s or more, more preferably 3 mm ² /s or more, still more preferably 3.5 mm ² /s or more. It is preferably 30 mm ² /s or less, more preferably 15 mm ² /s or less, still more preferably 10 mm ² /s or less. When the kinematic viscosity at 100° C. is 2 mm ² /s or more, evaporation loss is small, and when it is 30 mm ² /s or less, power loss due to viscous resistance is suppressed, resulting in improved fuel efficiency.
Although not particularly limited, the 40° C. kinematic viscosity of the base oil (A) is preferably 5 mm ² /s or more, more preferably 10 mm ² /s or more, still more preferably 15 mm ² /s or more, and , preferably 65 mm ² /s or less, more preferably 40 mm ² /s or less, still more preferably 25 mm ² /s or less.
The viscosity index of the base oil (A) is preferably 100 or higher, more preferably 110 or higher, even more preferably 115 or higher, and even more preferably 120 or higher. A base oil having a viscosity index of 100 or more has a small change in viscosity due to a change in temperature.
When the viscosity index of the base oil (A) is within this range, the viscosity characteristics of the lubricating oil composition can be easily improved.
The 40° C. kinematic viscosity, 100° C. kinematic viscosity and viscosity index of the base oil (A) are measured by the methods described in the examples below.

As the base oil (A), one having an aromatic content (% C _A ) determined by ring analysis of 3.0 or less and a sulfur content of 30 mass ppm or less is preferably used. Here, % C _A by ring analysis indicates the ratio (percentage) of the aromatic component calculated by the ring analysis ndM method.
The base oil having a % _CA of 3.0 or less and a sulfur content of 30 mass ppm or less has good oxidation stability, and provides a lubricating oil composition that can suppress an increase in acid value and sludge formation. can do. The % _CA is more preferably 1.0 or less, still more preferably 0.5 or less, still more preferably 0.1 or less, and a more preferable sulfur content is 20 ppm by mass or less, still more preferably 15 mass ppm or less, more preferably 10 mass ppm or less.
In addition, the base oil (A) preferably has a paraffin content (% C _P ) of 70 or more, more preferably 75 or more, and even more preferably 80 or more, as determined by ring analysis. By setting the % _CP to 70 or more, the oxidation stability of the base oil is improved. Here, % C _P by ring analysis indicates the ratio (percentage) of paraffin content calculated by the ring analysis ndM method.
The NOACK evaporation amount of the base oil (A) is preferably 15.0% by mass or less, more preferably 14.0% by mass or less.
The aromatic content (% C _A ), paraffin content (% C _P ), sulfur content (sulfur atom content), and NOACK evaporation amount determined by ring analysis of the base oil (A) are described in Examples described later. It is a value measured by the method

<Copolymer (B)>
The copolymer (B) used in the lubricating oil composition (hereinafter also simply referred to as "component (B)") is a structural unit derived from an alkyl (meth)acrylate having a branched alkyl group having 24 to 75 carbon atoms. (a) (hereinafter also simply referred to as "structural unit (a)") and a structural unit (b) represented by the following general formula (b1) (hereinafter also simply referred to as "structural unit (b)") include.

（一般式（ｂ１）中、Ｒ^１は炭素数１～２０の２価の炭化水素基を示し、Ｒ^２はメチル基又は水素原子を示す。ｍ及びｎは、それぞれ独立に、１～１０の整数であり、ｒ及びｓは、それぞれ独立に、１～３０の整数である。）

(In general formula (b1), R ¹ represents a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ² represents a methyl group or a hydrogen atom. m and n each independently represent 1 to 10 is an integer, and r and s are each independently an integer from 1 to 30.)

When the copolymer (B) is a polymer that does not contain the structural units (a) and (b), it becomes difficult to achieve both the friction-reducing effect and the corrosion-inhibiting effect.

(Constituent unit (a))
The structural unit (a) is a structural unit derived from an alkyl (meth)acrylate having a branched alkyl group having 24 to 75 carbon atoms.
The number of carbon atoms in the branched alkyl group having 24 to 75 carbon atoms is preferably 35 or more, more preferably 45 or more, still more preferably 55 or more, and preferably 70 or less, more preferably 68 or less, and still more preferably. is 65 or less.
The number of carbon atoms in the alkyl group refers to the number of carbon atoms in the alkyl group derived from the alkyl group represented by R ¹³ in the alkyl (meth)acrylate represented by the following general formula (am1).
That is, the (meth)acrylic acid having a branched alkyl group having 24 to 75 carbon atoms from which the structural unit (a) is derived is a monomer represented by the following general formula (am1).

（一般式（ａｍ１）中、Ｒ^１１はメチル基又は水素原子を示し、Ｒ^１２は炭素数２～４のアルキレン基を示し、Ｒ^１３は炭素数２４～７５の分岐アルキル基を示す。ｔは０又は１～２０の整数を指す。）

(In general formula (am1), R ¹¹ represents a methyl group or a hydrogen atom, R ¹² represents an alkylene group having 2 to 4 carbon atoms, and R ¹³ represents a branched alkyl group having 24 to 75 carbon atoms. t is Refers to an integer of 0 or 1 to 20.)

R ¹¹ is preferably a methyl group.
R ¹² is preferably methylene, ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl, butane-1,3-diyl and butane -1 selected from the group consisting of 2,2-diyl groups, more preferably 1 selected from the group consisting of ethylene groups, propane-1,3-diyl groups and butane-1,4-diyl groups, and more Ethylene group is preferred.
The number of carbon atoms in the branched alkyl group having 24 to 75 carbon atoms represented by R ¹³ is preferably 35 or more, more preferably 45 or more, still more preferably 55 or more, and preferably 70 or less, more preferably 68 or less. , and more preferably 65 or less.
t is preferably 0 or 1-10, more preferably 0 or 1-5, even more preferably 0.

The monomer represented by the general formula (am1) is preferably represented by the following general formula (am2).

（一般式（ａｍ２）中、Ｒ^１１はメチル基又は水素原子を示し、Ｒ^１４は炭素数１～８のアルキレン基を示し、Ｒ^１５及びＲ^１６は、それぞれ独立に、炭素数１～７３の直鎖又は分岐アルキル基を示し、好ましくは直鎖アルキル基である。ただし、Ｒ^１４、Ｒ^１５及びＲ^１６の合計炭素数は２３以上７４以下である。）

(In the general formula (am2), R ¹¹ represents a methyl group or a hydrogen atom, R ¹⁴ represents an alkylene group having 1 to 8 carbon atoms, R ¹⁵ and R ¹⁶ each independently represent a represents a linear or branched alkyl group, preferably a linear alkyl group, provided that the total carbon number of R ¹⁴ , R ¹⁵ and R ¹⁶ is 23 or more and 74 or less.)

R ¹¹ is preferably a methyl group.
R ¹⁴ is preferably an alkylene group having 1 to 4 carbon atoms, more preferably a methylene group or an ethylene group, still more preferably a methylene group.
The straight or branched alkyl group represented by R ¹⁵ preferably has 10 to 60 carbon atoms, more preferably 20 to 50 carbon atoms, still more preferably 25 to 40 carbon atoms, and even more preferably 28 to 34 carbon atoms.
The straight or branched alkyl group represented by R ¹⁶ preferably has 10 to 60 carbon atoms, more preferably 18 to 50 carbon atoms, still more preferably 22 to 36 carbon atoms, and even more preferably 24 to 30 carbon atoms.

The content of the structural unit (a) in the component (B) is preferably 40% by mass or more and 60% by mass or less based on 100% by mass of the total amount of the structural units of the component (B).

(Constituent unit (b))
The structural unit (b) is a structural unit represented by the following general formula (b1).

（一般式（ｂ１）中、Ｒ^１は炭素数１～２０の２価の炭化水素基を示し、Ｒ^２はメチル基又は水素原子を示す。ｍ及びｎは、それぞれ独立に、１～１０の整数であり、ｒ及びｓは、それぞれ独立に、１～３０の整数である。）

(In general formula (b1), R ¹ represents a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ² represents a methyl group or a hydrogen atom. m and n each independently represent 1 to 10 is an integer, and r and s are each independently an integer from 1 to 30.)

R ¹ is a divalent hydrocarbon group having 1 to 20 carbon atoms, and the number of carbon atoms of the divalent hydrocarbon group is preferably 1 to 12, more preferably 2 to 8, and still more preferably 4 to 6. be.
R ² is preferably a methyl group.
m and n are each independently preferably an integer of 2-8, more preferably an integer of 3-7, and still more preferably an integer of 4-6. Even more preferably, m and n are the same as each other.
r and s are each independently preferably an integer of 2-20, more preferably an integer of 3-15, even more preferably an integer of 4-10, and even more preferably an integer of 4-6. Even more preferably, r and s are the same as each other.

Further, the structural unit (b) is more preferably a structural unit represented by the following general formula (b2).

（一般式（ｂ２）中、Ｒ^２はメチル基又は水素原子を示し、Ｒ^３は炭素数２～８の２価の炭化水素基を表す。）

(In general formula (b2), R ² represents a methyl group or a hydrogen atom, and R ³ represents a divalent hydrocarbon group having 2 to 8 carbon atoms.)

R ² is preferably a methyl group.
R ³ is a divalent hydrocarbon group having 2 to 8 carbon atoms, and the divalent hydrocarbon group preferably has 4 to 6 carbon atoms, more preferably 4 or 6 carbon atoms.

The structural unit (b) is a structural unit derived from a monomer represented by the following general formula (bm1).

（一般式（ｂｍ１）中、Ｒ^１、Ｒ^２、ｍ、ｎ、ｒ及びｓは、一般式（ｂ１）で定義したとおりである。）

(In general formula (bm1), R ¹ , R ² , m, n, r and s are as defined in general formula (b1).)

In the general formula (bm1), R ¹ , R ² , m, n, r and s are as defined in the general formula (b1), and their preferred embodiments are also the same, so the description is omitted.

The content of the structural unit (b) in the component (B) is preferably 10% by mass or more and 60% by mass or less based on 100% by mass of the total amount of the structural units of the component (B).

(Constituent unit (c))
In addition to the structural units (a) and (b), the component (B) further includes an amino group-containing monomer and a quaternary ammonium base-containing monomer from the viewpoint of improving the friction reducing effect. a structural unit (c) derived from one or more monomers selected from the group consisting of monomers, nitrile group-containing monomers and nitro group-containing monomers (hereinafter also simply referred to as "structural unit (c)"). ) is preferably included.
As the monomer from which the structural unit (c) is derived, more preferably one or more monomers selected from the group consisting of amino group-containing monomers and quaternary ammonium base-containing monomers, and further Preferred are amino group-containing monomers.

Examples of the amino group-containing monomer include monomers having at least one primary, secondary or tertiary amino group in the molecule, such as amino group-containing aliphatic monomers, amino group Heterocyclic monomer-containing monomers, amino group-containing aromatic monomers, and salts thereof (eg, hydrochlorides, phosphates and carboxylates having 1 to 8 carbon atoms) can be mentioned.

Examples of the amino group-containing aliphatic monomer include monomers represented by the following general formula (cm1) or (cm2), preferably monomers represented by the following general formula (cm1). be done.

（一般式（ｃｍ１）中、Ｒ^２１はメチル基又は水素原子を示し、Ｒ^２２は炭素数１～６のアルキレン基を示し、Ｒ^２４及びＲ^２３は、それぞれ独立に、水素原子又は炭素数１～４の直鎖若しくは分岐アルキル基を示す。）

(In general formula (cm1), R ²¹ represents a methyl group or a hydrogen atom, R ²² represents an alkylene group having 1 to 6 carbon atoms, R ²⁴ and R ²³ each independently represent a hydrogen atom or a indicates a linear or branched alkyl group of ~4.)

R ²¹ is preferably a methyl group.
R ²² is preferably an alkylene group having 1 to 4 carbon atoms, more preferably a methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, propane-1,1-diyl group , butane-1,4-diyl group, butane-1,3-diyl group, butane-1,2-diyl group, butane-1,1-diyl group, butane-2,3-diyl group, and butane-2 , 2-diyl group, more preferably one selected from the group consisting of ethylene group, propane-1,3-diyl group and butane-1,4-diyl group, still more preferably Ethylene group.
R ²⁴ and R ²³ are each independently preferably one selected from the group consisting of methyl group, ethyl group, n-propyl group, n-butyl group, isobutyl group and tert-butyl group, more preferably methyl group , an ethyl group and a tert-butyl group, more preferably a methyl group or an ethyl group, and even more preferably a methyl group.
Specific examples of suitable amino group-containing monomers represented by the general formula (cm1) include (meth)acrylic acid-N,N-dimethylaminoethyl ester, (meth)acrylic acid-N,N-diethylamino One or more tertiary amino group-containing monomers selected from the group consisting of ethyl ester and (meth)acrylic acid-N,N-di-t-butylaminoethyl ester, more preferably (meth)acrylic Acid-N,N-dimethylaminoethyl ester.

（一般式（ｃｍ２）中、Ｒ^２５は炭素数２～１０のアルケニル基を示し、Ｒ^２６は水素原子又は炭素数２～１０のアルケニル基を示す。）

(In general formula (cm2), R ²⁵ represents an alkenyl group having 2 to 10 carbon atoms, and R ²⁶ represents a hydrogen atom or an alkenyl group having 2 to 10 carbon atoms.)

R ²⁵ is preferably an alkenyl group having 3 to 6 carbon atoms, and when R ²⁶ is an alkenyl group, it is preferably an alkenyl group having 3 to 6 carbon atoms.
Specific examples of suitable amino group-containing monomers represented by the general formula (cm2) include mono(meth)allylamine, di(meth)allylamine, allylmethallylamine, 2-butenylamine, and isocrotylamine. mentioned.

Examples of the amino group-containing heterocyclic monomers include amino group-containing heterocyclic acrylic monomers and vinyl-substituted heterocyclic amines. Specific examples of amino group-containing heterocyclic acrylic monomers include morpholino-C _2-4 alkyl (meth)acrylates such as morpholinoethyl (meth)acrylate. Specific examples of vinyl-substituted heterocyclic amines include vinylpyridines such as 4-vinylpyridine and 2-vinylpyridine; N-vinylpyrrole; and N-vinylpyrrolidine. Here, the description “C _2-4 alkyl” is synonymous with “C 2-4 alkyl”. Hereinafter, the description “C _XY alkyl” (X and Y are arbitrary integers) is synonymous with “alkyl having X to Y carbon atoms”.

Examples of the amino group-containing aromatic monomer include aminostyrenes such as aminostyrene, aminomethylstyrene, methylaminostyrene and dimethylaminostyrene.

The amino group-containing monomer preferably includes a monomer represented by the general formula (cm1).

The quaternary ammonium base-containing monomer is a quaternary ammonium salt obtained by quaternization of the amino group-containing monomer. Examples of the quaternizing agent used for the quaternization include alkyl halides having an alkyl group having 1 to 8 carbon atoms such as methyl chloride; benzyl halides such as benzyl chloride; di-C _{1- 2-} alkyl sulfates; and di-C _1-2 alkyl carbonates such as dimethyl carbonate;
Further, as the quaternary ammonium base-containing monomer, one or more selected from the group consisting of alkylene oxides having 2 to 4 carbon atoms such as ethylene oxide and propylene oxide are added to salts of the amino group-containing monomers. Also included are quaternary ammonium salts obtained by quaternization of

Examples of the nitrile group-containing monomer include (meth)acrylonitrile.
Examples of the nitro group-containing monomer include nitrostyrene.

When the component (B) contains the structural unit (c), the content of the structural unit (c) is preferably 1% by mass or more and 50 % by mass or less.

In the component (B), the total content of the structural units (a) to (c) is preferably 80% by mass or more, more preferably 90% by mass, based on 100% by mass of the total amount of the structural units of the component (B). % by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, and preferably 100% by mass or less.

(Other structural units)
The component (B) may further contain other structural units in addition to the structural units (a) to (c) as long as the effects of the present invention are not impaired.
Structural units other than the structural units (a) to (c) include, for example, a structural unit derived from an alkyl (meth)acrylate other than the monomers constituting the structural unit (a); the structural unit (b); Structural units derived from functional group-containing monomers other than the monomers constituting (c) are exemplified.
Examples of alkyl (meth)acrylates other than the monomers constituting the structural unit (a) include alkyl (meth)acrylates having a linear or branched alkyl group having 1 to 23 carbon atoms, wherein the alkyl group alkyl (meth)acrylate having a total carbon number of less than 24; alkyl (meth)acrylate having no branched alkyl group and having a linear alkyl group having 24 to 75 carbon atoms;

Examples of structural units derived from functional group-containing monomers other than monomers constituting the structural unit (b) or (c) include, for example, a structure derived from hydroxyalkyl (meth)acrylate represented by the following general formula (d1) A unit (d) can be mentioned.

（一般式（ｄ１）中、Ｒ^４はメチル基又は水素原子を示し、Ｒ^５は炭素数２～４のアルキレン基を示す。）

(In general formula (d1), R ⁴ represents a methyl group or a hydrogen atom, and R ⁵ represents an alkylene group having 2 to 4 carbon atoms.)

^R4 is preferably a hydrogen atom.
R ⁵ is preferably ethylene, propane-1,3-diyl, propane-1,2-diyl, propane-1,1-diyl, butane-1,4-diyl, butane-1,3 -one selected from the group consisting of a diyl group, butane-1,2-diyl group, butane-1,1-diyl group, butane-2,3-diyl group, and butane-2,2-diyl group, and preferably one selected from the group consisting of ethylene group, propane-1,3-diyl group, propane-1,2-diyl group and propane-1,1-diyl group, more preferably ethylene group or propane-1, A 3-diyl group, more preferably an ethylene group.

Component (B) preferably has a weight average molecular weight (Mw) of 2,000 to 200,000, more preferably 5,000 to 100,000, still more preferably 10,000 to 50,000.
In addition, the said mass average molecular weight (Mw) is measured by the method as described in the Example mentioned later.
Further, the form of the copolymer which is the component (B) may be, for example, any of a random addition polymer, an alternating copolymer, a graft copolymer and a block copolymer.

The component (B) can be produced using a known polymerization method. For example, it can be obtained by radically polymerizing the monomers, which are the raw materials of the respective structural units described above, in a solvent.
The solvent may be any solvent that dissolves the monomer, and aromatic hydrocarbon solvents such as toluene, xylene, alkylbenzene having 9 to 10 carbon atoms; C6 solvents such as hexane, heptane, cyclohexane, octane ~18 aliphatic hydrocarbon solvents; 2-propanol, 1-butanol, alcohol solvents having 3 to 8 carbon atoms such as 2-butanol; ketone solvents such as methyl ethyl ketone; can. Among these, mineral oil is preferred.

Examples of radical polymerization initiators that can be used in the radical polymerization include azo polymerization initiators and peroxide polymerization initiators.
Examples of azo polymerization initiators include 2,2′-azobis(isobutyronitrile) (abbreviation: AIBN), 2,2′-azobis(2-methylbutyronitrile) (abbreviation: AMBN), 2, 2'-azobis(2,4-dimethylvaleronitrile) (abbreviation: ADVN), 4,4'-azobis(4-cyanovaleric acid) (abbreviation: ACVA), dimethyl 2,2'-azobisisobutyrate, etc. is mentioned.
Peroxide polymerization initiators include, for example, tert-butyl peroxypivalate, tert-hexyl peroxypivalate, tert-butyl peroxyneoheptanoate, tert-butyl peroxyneodecanoate, tert-butyl peroxy 2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-amyl peroxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexanoate, dibutyl peroxytrimethyl adipate, benzoyl peroxide, cumyl peroxide, lauryl peroxide and the like.

In the radical polymerization, known chain transfer agents such as chlorine-containing compounds, alkylbenzene compounds, and mercaptan compounds can be used as necessary for the purpose of adjusting physical properties of the polymer such as molecular weight. Examples of the mercaptan compound include alkyl groups having 2 to 20 carbon atoms such as n-butylmercaptan, isobutylmercaptan, n-octylmercaptan, n-dodecylmercaptan, sec-butylmercaptan, tert-butylmercaptan, and tert-dodecylmercaptan. Alkyl mercaptan compounds having
The amount of the polymerization initiator and the chain transfer agent to be used can be appropriately selected in consideration of the physical properties of the desired polymer (for example, adjustment of molecular weight, etc.).

Although the reaction temperature can be adjusted as appropriate, it is, for example, 50 to 140°C, preferably 60 to 120°C.
In addition to the above solution polymerization, it can also be produced using polymerization methods such as bulk polymerization, emulsion polymerization, and suspension polymerization.

The content of the component (B) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and still more preferably 0.8% by mass, based on the total amount (100% by mass) of the lubricating oil composition. % or more, and preferably 3.0% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1.3% by mass or less.

<Other ingredients>
The lubricating oil composition, which is one aspect of the present invention, further contains other components other than the components (A) and (B) as necessary within a range that does not impair the effects of the present invention. good too.
Other components include commonly used lubricating oil additives. Examples of such lubricating oil additives include metallic detergents, antiwear agents, ashless dispersants, viscosity index improvers, One or more selected from the group consisting of extreme pressure agents, pour point depressants, antioxidants, antifoaming agents, surfactants, demulsifiers, friction modifiers, oiliness improvers, rust inhibitors and metal deactivators is mentioned.
As the lubricating oil additive, a commercially available additive package containing multiple additives that conforms to the European Automobile Manufacturers Association (ACEA) standards, API / ILSAC SN / GF-5 standards, etc. good too.
A compound having multiple functions as the additive (for example, a compound having functions as an anti-wear agent and an extreme pressure agent) may also be used.
Furthermore, each of these lubricating oil additives may be used alone, or two or more of them may be used in combination.

The content of each of these lubricating oil additives can be appropriately adjusted within a range that does not impair the effects of the present invention. 001 to 15% by mass, preferably 0.005 to 10% by mass, more preferably 0.01 to 8% by mass.
Further, in the lubricating oil composition of one aspect of the present invention, the total content of these lubricating oil additives is based on the total amount (100% by mass) of the lubricating oil composition, preferably 0 to 30% by mass, more It is preferably 0 to 25% by mass, more preferably 0 to 20% by mass, and even more preferably 0 to 15% by mass.

(Metallic detergent)
Examples of metal-based detergents include organic acid metal salt compounds containing metal atoms selected from alkali metals and alkaline earth metals, and specifically, metal atoms selected from alkali metals and alkaline earth metals. containing metal salicylates, metal phenates, and metal sulfonates.
In this specification, the term "alkali metal" refers to lithium, sodium, potassium, rubidium, cesium, and francium.
Also, "alkaline earth metal" refers to beryllium, magnesium, calcium, strontium, and barium.
The metal atom contained in the metallic detergent is preferably sodium, calcium, magnesium, or barium, more preferably calcium, from the viewpoint of improving detergency at high temperatures.

The metal salicylate is preferably a compound represented by the following general formula (1), the metal phenate is preferably a compound represented by the following general formula (2), and the metal sulfonate is preferably a compound represented by the following general formula (3 ) are preferred.

In the general formulas (1) to (3), M is a metal atom selected from alkali metals and alkaline earth metals, preferably sodium, calcium, magnesium or barium, more preferably calcium. M ^E is an alkaline earth metal, preferably calcium, magnesium or barium, more preferably calcium. p is the valence of M and is 1 or 2; R ³¹ and R ³² are each independently a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms. S represents a sulfur atom. q is an integer of 0 or more, preferably an integer of 0-3.
Hydrocarbon groups that can be selected as R ³¹ and R ³² include, for example, alkyl groups having 1 to 18 carbon atoms, alkenyl groups having 1 to 18 carbon atoms, cycloalkyl groups having 3 to 18 ring carbon atoms, and ring carbon atoms. Examples include aryl groups having 6 to 18 carbon atoms, alkylaryl groups having 7 to 18 carbon atoms, arylalkyl groups having 7 to 18 carbon atoms, and the like.

In one aspect of the present invention, these metallic detergents may be used alone or in combination of two or more. Among these, one or more selected from calcium salicylate, calcium phenate, and calcium sulfonate is preferred from the viewpoint of improving detergency at high temperatures and from the viewpoint of solubility in base oil.

In one aspect of the present invention, these metallic detergents may be neutral salts, basic salts, overbased salts and mixtures thereof.
The total base number of the metallic detergent is preferably 0 to 600 mgKOH/g.
In one aspect of the present invention, when the metallic detergent is a basic salt or an overbased salt, the total base number of the metallic detergent is preferably 10 to 600 mgKOH/g, more preferably 20 to 500 mg KOH/g.
As used herein, the term “base number” refers to 7. of JIS K2501:2003 “Petroleum products and lubricating oils—neutralization value test method”. Means the base number by the perchloric acid method measured in accordance with.

When the lubricating oil composition of one aspect of the present invention contains a metallic detergent as another component, the content of the metallic detergent is the content in terms of metal atoms based on the total amount of the composition, preferably 0 .01 to 0.50% by mass, more preferably 0.02 to 0.40% by mass, still more preferably 0.03 to 0.30% by mass, still more preferably 0.035 to 0.25% by mass .
In addition, the said metallic detergent may be used individually and may use 2 or more types together. The preferred total content when using two or more types is also the same as the content described above.

(Antiwear agent)
Examples of antiwear agents include sulfur-containing compounds such as zinc dialkyldithiophosphate (ZnDTP), zinc phosphate, disulfides, sulfurized olefins, sulfurized oils and fats, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfides. phosphorus-containing compounds such as phosphites, phosphates, phosphonates, and their amine salts or metal salts; thiophosphites, thiophosphates, thiophosphonates, and these sulfur- and phosphorus-containing antiwear agents such as amine salts or metal salts of
Among these, zinc dialkyldithiophosphate (ZnDTP) is preferred.

In the lubricating oil composition of one aspect of the present invention, when an anti-wear agent is contained as another component, the anti-wear agent is such that the metal content, phosphorus content, and sulfur content in the lubricating oil composition are reduced as much as possible. is preferable, and the content of the antiwear agent is preferably 0.01 to 5.0% by mass, more preferably 0.1 to 3.0% by mass, based on the total amount (100% by mass) of the lubricating oil composition , more preferably 0.5 to 1.5% by mass.
In addition, the said anti-wear agent may be used individually and may use 2 or more types together. The preferred total content when using two or more types is also the same as the content described above.

(ashless dispersant)
Examples of the ashless dispersant include succinimide, benzylamine, succinic acid ester, boron-modified products thereof, and the like, and alkenylsuccinimide and boron-modified alkenylsuccinimide are preferred.

Examples of alkenylsuccinimides include alkenylsuccinic acid monoimides represented by the following general formula (i) and alkenylsuccinic acid bisimides represented by the following general formula (ii).
The alkenylsuccinimide is a compound represented by the following general formula (i) or (ii), and one or more selected from alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, organic acids, and the like. may be used as a modified alkenylsuccinimide reacted with.
Boron-modified alkenylsuccinimides include boron-modified compounds represented by the following general formula (i) or (ii).

In the general formulas (i) and (ii), R ^A , R ^A1 and R ^A2 each independently have a mass average molecular weight (Mw) of 500 to 3,000 (preferably 1,000 to 3,000). It is an alkenyl group, preferably a polybutenyl group or a polyisobutenyl group.
R ^B , R ^B1 and R ^B2 are each independently an alkylene group having 2 to 5 carbon atoms.
x1 is an integer of 1-10, preferably an integer of 2-5, more preferably 3 or 4.
x2 is an integer of 0-10, preferably an integer of 1-4, more preferably 2 or 3.

In one aspect of the present invention, the ratio [B/N] of boron atoms and nitrogen atoms constituting the boron-modified alkenylsuccinimide is preferably 0.5 or more, more preferably 0, from the viewpoint of improving cleanliness. 0.6 or more, more preferably 0.8 or more, and even more preferably 0.9 or more.

(Viscosity index improver)
Viscosity index improvers include, for example, non-dispersed polyalkyl (meth)acrylate, PMA-based dispersant polyalkyl (meth)acrylate; type olefin copolymers; styrene copolymers (eg, styrene-diene copolymers, styrene-isoprene copolymers, etc.);
These viscosity index improvers preferably have a weight average molecular weight (Mw) of 5,000 to 1,500,000, and in the case of PMA systems, preferably 20,000 or more, more preferably 100,000 or more. and is preferably 1,000,000 or less, more preferably 800,000 or less. In the case of an OCP system, it is preferably 10,000 or more, more preferably 20,000 or more, and preferably 800,000 or less, more preferably 500,000 or less.
In addition, the said mass average molecular weight (Mw) is measured, for example by the method as described in the Example mentioned later.
The structure of the viscosity index improver may be linear or branched. Also, a comb-shaped polymer having a structure with many trigeminal branch points in the main chain from which high-molecular-weight side chains come out, and a type of branched polymer in which three or more chain-like polymers are bonded at one point It may also be a polymer with a specific structure, such as a structured star polymer.

In addition, as the viscosity index improver, as described above, a polymer having a structure having many trigeminal branch points from which linear side chains protrude in the main chain (hereinafter referred to as "comb-shaped polymer") is contained. good too. Preferred examples of such comb-shaped polymers include polymers having at least structural units derived from macromonomers having polymerizable functional groups such as methacryloyl groups, acryloyl groups, ethenyl groups, vinyl ether groups, and allyl groups. Here, the structural unit corresponds to a "linear side chain".
More specifically, alkyl (meth)acrylates, nitrogen atom-containing systems, halogen element-containing systems, hydroxyl group-containing systems, aliphatic hydrocarbon systems, alicyclic hydrocarbon systems, aromatic hydrocarbon systems, etc. Preferable examples include copolymers having side chains containing structural units derived from macromonomers having the polymerizable functional groups with respect to main chains containing structural units derived from polymerizable functional groups.

The number average molecular weight (Mn) of the macromonomer is preferably 200 or more, more preferably 300 or more, still more preferably 400 or more, and preferably 100,000 or less, more preferably 50,000 or less, and still more preferably 10,000 or less.
In addition, the mass average molecular weight (Mw) of the comb polymer is preferably 1,000 or more, more preferably 5,000 or more, and still more preferably 50,000 or more, from the viewpoint of improving fuel efficiency, and It is preferably 1,000,000 or less, more preferably 800,000 or less, still more preferably 700,000 or less. The molecular weight distribution (Mw/Mn) is preferably 6 or less, more preferably 5.6 or less, and still more preferably 5 or less. .05 or greater, more preferably 1.10 or greater, and even more preferably 1.50 or greater.

The viscosity index improver is preferably a polyalkyl (meth)acrylate having a PSSI of 30 or less. Here, PSSI means Permanent Shear Stability Index and indicates the ability of a polymer (polyalkyl (meth)acrylate) to resist degradation. The higher the PSSI, the more shear-labile the polymer and the more susceptible it is to degradation. PSSI indicates the percentage of viscosity reduction due to shear derived from the polymer, and is calculated by the following formula defined in ASTM D6022-06 (2012).

In the formula, Kv ₀ is the 100° C. kinematic viscosity of a mixture of base oil and polyalkyl (meth)acrylate. Kv ₁ is the 100° C. kinematic viscosity value after passing a mixture of base oil plus polyalkyl (meth)acrylate through a 30 cycle high shear Bosch diesel injector according to the procedure of ASTM D6278. Kv _oil is the 100° C. kinematic viscosity of the base oil. A Group II base oil having a kinematic viscosity of 5.35 mm ² /s at 100° C. and a viscosity index of 105 is used as the base oil.
By using a polyalkyl (meth)acrylate with a PSSI of 30 or less, the antiwear properties of the lubricating oil composition can be further enhanced. The PSSI is more preferably 1 or more and 25 or less. By setting the PSSI to 25 or less, the anti-wear property of the lubricating oil composition can be further enhanced.

The monomer constituting the polyalkyl (meth) acrylate is an alkyl (meth) acrylate, preferably an alkyl (meth) acrylate having a linear alkyl group having 1 to 18 carbon atoms or a branched alkyl group having 3 to 34 carbon atoms. is.
The polystyrene-equivalent mass average molecular weight (Mw) of the polyalkyl (meth)acrylate is preferably 10,000 or more and 1,000,000 or less, more preferably 30,000 or more and 500,000 or less. By setting the weight average molecular weight of the polyalkyl (meth)acrylate within this range, the SSI value can be easily adjusted to 30 or less.
In addition, the said mass average molecular weight (Mw) is measured by the method as described in the Example mentioned later.

These viscosity index improvers may be used alone or in combination of two or more.
In addition, the viscosity index improver contains, as a resin component, for example, the above-mentioned polymer other than the component (B). It is often marketed in the form of a solution diluted with a diluent oil such as mineral oil. The resin concentration of the viscosity index improver is generally 10% by mass or more and 50% by mass or less based on the total amount of the viscosity index improver.
In this case, the content of the viscosity index improver when using the viscosity index improver is preferably 0.001% by mass based on the total amount (100% by mass) of the lubricating oil composition as the content in terms of resin content Above, more preferably 0.05% by mass or more, still more preferably 0.5% by mass or more, and preferably 10.0% by mass or less, more preferably 7.5% by mass or less, still more preferably 5.5% by mass or less. It is 0% by mass or less.

(extreme pressure agent)
Examples of extreme pressure agents include sulfur-based extreme-pressure agents such as sulfides, sulfoxides, sulfones and thiophosphinates, halogen-based extreme-pressure agents such as chlorinated hydrocarbons, and organic metal-based extreme-pressure agents. be done. Further, among the antiwear agents described above, a compound having a function as an extreme pressure agent can also be used.
In one aspect of the present invention, these extreme pressure agents may be used alone or in combination of two or more.

(Antioxidant)
As the antioxidant, any of known antioxidants conventionally used as antioxidants for lubricating oils can be appropriately selected and used. Examples include antioxidants, molybdenum-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.
Examples of amine-based antioxidants include diphenylamine-based antioxidants such as diphenylamine and alkylated diphenylamine having an alkyl group of 3 to 20 carbon atoms; naphthylamine-based antioxidants such as substituted phenyl-α-naphthylamine having a group;
Phenolic antioxidants include, for example, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, Monophenol antioxidants such as isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate agent; diphenol antioxidants such as 4,4'-methylenebis(2,6-di-tert-butylphenol) and 2,2'-methylenebis(4-ethyl-6-tert-butylphenol); hindered phenol antioxidant; and the like.
Molybdenum-based antioxidants include, for example, molybdenum amine complexes obtained by reacting molybdenum trioxide and/or molybdic acid with an amine compound.
Examples of sulfur-based antioxidants include dilauryl-3,3'-thiodipropionate and the like.
Examples of phosphorus-based antioxidants include phosphites. When a phosphorus-based antioxidant is used, it is preferable that the content of the phosphorus atom satisfies the suitable phosphorus atom content of the lubricating oil composition described later.
In one aspect of the present invention, these antioxidants may be contained alone or in any combination of two or more, preferably phenolic antioxidants and/or amine antioxidants.

(Pour point depressant)
Examples of the pour point depressant include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates (PMA; polyalkyl (meth) acrylate, etc.), polyvinyl acetate, polybutene, polyalkylstyrene, etc., and polymethacrylates are preferably used. These pour point depressants may be used alone or in combination of two or more.

(Antifoaming agent)
Antifoaming agents include, for example, silicone oils such as dimethylpolysiloxane, fluorosilicone oils, and fluoroalkyl ethers. These antifoaming agents may be contained alone or in any combination of two or more.

(Surfactant or emulsifier)
Examples of surfactants or demulsifiers include polyalkylene glycol-based nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxyethylene alkylnaphthyl ethers. These surfactants or demulsifiers can be contained alone or in any combination of two or more.

(friction modifier)
Examples of friction modifiers include molybdenum-based friction modifiers such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdic acid; Ashless friction modifiers, such as fatty amines, fatty acid esters, fatty acid amides, fatty acids, fatty alcohols, and fatty ethers, having at least one; , phosphate ester amine salts, and the like.
However, from the viewpoint of suppressing corrosiveness to copper, the content of the friction modifier, which is a sulfur-containing compound such as molybdenum dithiocarbamate (MoDTC), in terms of molybdenum atoms, is preferably 0.00% based on the total amount of the lubricating oil composition. 04% by mass or less, more preferably 0.01% by mass or less, and more preferably not contained.

(oiliness improver)
Oiliness improvers include aliphatic saturated or unsaturated monocarboxylic acids such as stearic acid and oleic acid; polymerized fatty acids such as dimer acid and hydrogenated dimer acid; hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid; lauryl alcohol , aliphatic saturated or unsaturated monoalcohols such as oleyl alcohol; aliphatic saturated or unsaturated monoamines such as stearylamine and oleylamine; aliphatic saturated or unsaturated monocarboxylic acid amides such as lauric amide and oleic amide; glycerin, partial esters of polyhydric alcohols such as sorbitol and aliphatic saturated or unsaturated monocarboxylic acids;

(anti-rust)
Rust inhibitors include, for example, fatty acids, alkenylsuccinic acid half esters, fatty acid soaps, alkylsulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, paraffin oxide, and alkylpolyoxyethylene ethers.

(Metal deactivator)
Examples of metal deactivators include benzotriazole-based compounds, tolyltriazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, and pyrimidine-based compounds.

<Properties of lubricating oil composition>
The content of phosphorus atoms in the lubricating oil composition is preferably 0.10% by mass or less based on the total amount (100% by mass) of the lubricating oil composition. Usually, the content of phosphorus atoms in the lubricating oil composition is desirable to some extent from the viewpoint of wear resistance, etc. On the other hand, phosphorus-containing compounds are required to be reduced from the viewpoint of reducing the environmental load. It is The lubricating oil composition which is one embodiment of the present invention has an excellent friction reducing effect even when the phosphorus atom content is low. From such a viewpoint, the content of the phosphorus atom is preferably 0.10% by mass or less, more preferably 0.09% by mass or less, and still more preferably 0% by mass, based on the total amount (100% by mass) of the lubricating oil composition. 08% by mass or less.
Moreover, the lower limit of the phosphorus atom content is not particularly limited, and when the phosphorus atom is contained, it is, for example, 0.001% by mass or more based on the total amount of the lubricating oil composition.
The phosphorus atom content can be adjusted by adjusting the amount of the additive containing a phosphorus atom among the other additives described above.
The phosphorus atom content is a value measured by the method described in the examples below.

In addition, the content of molybdenum atoms in the lubricating oil composition is based on the total amount (100% by mass) of the lubricating oil composition, preferably 0.05% by mass or less, more preferably 0.04% by mass or less, and further It is preferably 0.03% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0.001% by mass or less.
The lower limit of the molybdenum atom content is not particularly limited, and when molybdenum atoms are contained, it is, for example, 0.0002% by mass or more based on the total amount of the lubricating oil composition.
The content of molybdenum atoms is a value measured by the method described in Examples below.
The content of molybdenum atoms can be adjusted by adjusting the amount of the additive containing molybdenum atoms among the other additives described above.
The sulfated ash content of the lubricating oil composition is preferably 0.8% by mass or less, more preferably 0.6% by mass or less, and even more preferably 0.5% by mass or less.
The sulfated ash content is a value measured according to JIS K2272:1998.

In addition, the 100° C. kinematic viscosity of the lubricating oil composition is preferably 1 to 30 mm ² /s, more preferably 2 to 15 mm ² /s, still more preferably 3 to 10 mm ² /s.
In addition, the 40° C. kinematic viscosity of the lubricating oil composition of the present embodiment is preferably 5 to 65 mm ² /s, more preferably 8 to 55 mm ² /s, still more preferably 10 to 45 mm ² /s.
The viscosity index of the lubricating oil composition of the present embodiment is preferably 100 or higher, more preferably 120 or higher, even more preferably 125 or higher.
Each of the above kinematic viscosities and viscosity indices is a value measured by the method described in Examples below.

In addition, the value of the friction coefficient of the lubricating oil composition evaluated by the method described in the examples described later is preferably 0.08 or less, more preferably 0.06 or less, still more preferably 0.05 or less, and more More preferably 0.04 or less, still more preferably 0.03 or less. When the friction coefficient is low, the lubricating oil composition has an excellent effect of reducing friction at high temperatures.

In addition, the copper elution amount of the lubricating oil composition evaluated by the method described in Examples below is preferably 10 ppm by mass or less, more preferably 5 ppm by mass or less, and even more preferably less than 2 ppm by mass.

[Method for producing lubricating oil composition]
A method for producing a lubricating oil composition, which is one embodiment of the present invention, comprises a base oil (A), a structural unit (a) derived from an alkyl (meth)acrylate having a branched alkyl group having 24 to 75 carbon atoms, and the above A copolymer (B) containing a structural unit (b) represented by general formula (b1) is blended.
Moreover, in the said manufacturing method, you may further mix|blend other components other than a component (A) and a component (B) as needed.
Component (A), component (B), and other components are the same as those described for the lubricating oil composition, and the preferred aspects of each are also the same, and the lubricating oil obtained by the production method Since the composition is also as described above, the description thereof is omitted.
In the production method, the components (A) and (B) and other components added as necessary may be blended into the base oil by any method, and the method is not limited.

[Use of lubricating oil composition]
The lubricating oil composition which is one embodiment of the present invention is used as a lubricating oil for internal combustion engines such as motorcycles, automobiles such as four-wheeled vehicles, generators, ships, etc., such as gasoline engines, diesel engines, and gas engines. It can be suitably used as a lubricating oil that is filled in the internal combustion engine and lubricates between parts of the internal combustion engine. More preferably, it can be used as a lubricating oil for lubricating the internal combustion engine including members containing copper.
In addition, the lubricating oil composition according to one embodiment of the present invention exhibits an excellent friction reducing effect even at high temperatures, unlike conventional ashless friction modifiers, even when no metallic friction modifier is used. have. Therefore, component (B), which is one embodiment of the present invention, can be used as a friction modifier for the lubricating oil composition. And, for example, in recent years, as environmental regulations have become stricter, as described above, it is desired to reduce the metal content, sulfur content, and phosphorus content in lubricating oil compositions derived from metallic friction modifiers such as MoDTC as much as possible. ing. Therefore, for the reason described above, the lubricating oil composition of one embodiment of the present invention is a lubricating oil for internal combustion engines such as gasoline engines, diesel engines, or dimethyl ether fueled engines and gas engines with strict environmental regulations. It is also suitable as a composition.

[Lubrication method using lubricating oil composition]
Therefore, as a lubricating method using the lubricating oil composition which is one embodiment of the present invention, preferably, the lubricating oil composition is mounted on an automobile such as a two-wheeled vehicle, a four-wheeled vehicle, a generator, a ship, etc. a method of filling an internal combustion engine such as a gasoline engine, a diesel engine, a gas engine, etc., and lubricating between parts related to the internal combustion engine. Further, for example, a lubricating method characterized by using the lubricating oil composition for a member containing copper, more preferably filling the internal combustion engine containing a member containing copper, A method of lubricating between parts containing the copper is mentioned.
Further, for the same reason as described above, the lubricating oil composition which is one embodiment of the present invention is used for internal combustion engines such as gasoline engines, diesel engines, or dimethyl ether fueled engines and gas engines with strict environmental regulations. Another suitable example is a method of filling an engine and lubricating between parts of the internal combustion engine.

[Internal combustion engine using lubricating oil composition]
Another embodiment of the present invention includes an internal combustion engine using the lubricating oil composition, preferably an internal combustion engine (engine) using the lubricating oil composition as an engine oil. Examples of the internal combustion engine include automobiles such as two-wheeled vehicles and four-wheeled vehicles, generators, and gasoline engines, diesel engines, and gas engines mounted on ships and the like. Among these internal combustion engines, internal combustion engines containing members containing copper are more preferred.

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

In this specification, each raw material used in each example and each comparative example and each physical property of the lubricating oil composition of each example and each comparative example were obtained according to the following procedures.
<Kinematic viscosity (40°C kinematic viscosity, 100°C kinematic viscosity)>
It is a value measured using a glass capillary viscometer according to JIS K2283:2000.
<Viscosity index>
It is a value calculated according to JIS K2283:2000.
<NOACK Evaporation Amount>
It is a value measured according to the method specified in ASTM D5800 (250°C, 1 hour).
<Ring Analysis (% C _A and % C _P )>
The ratio (percentage) of the aromatic content calculated by the ring analysis ndM method is shown as %C _A , and the ratio (percentage) of the paraffin content is shown as %C _P , which were measured according to ASTM D-3238. It is.
<Base value>
It is measured by a potentiometric titration method (base number/perchloric acid method) in accordance with JIS K2501:2003.
<Molybdenum Atom Content, Calcium Atom, Zinc Atom, and Phosphorus Atom Content>
Measured according to JPI-5S-38-2003.
<Content of sulfur atom>
It is a value measured according to JIS K2541-6:2013 (ultraviolet fluorescence method).
<Method for confirming structural units in component (B)>
It was confirmed from chemical shifts and integral values of ¹ H-NMR and ¹³ C-NMR obtained using a nuclear magnetic resonance (NMR) apparatus (manufactured by JEOL Ltd., "ECX-400P"). Specifically, the structure of the structural unit was confirmed from the integrated value of the peak of the structural unit. Measurement conditions are shown below.
Solvent: deuterated chloroform Reference material: tetramethylsilane (TMS)
Resonance frequency: 100MHz
Measurement mode: Decoupling method with gate Accumulation times: 2000 to 5000
Pulse delay time: 25s
Pulse width: 9.25 μs
x-angle: 90°
<Mass average molecular weight (Mw)>
Using a gel permeation chromatograph (manufactured by Tosoh Corporation, "HLC 8220"), measurements were made under the following conditions, and the values measured in terms of standard polystyrene were used.
(Measurement condition)
・Column: "TOSOH TSK-GEL GHXL-L"
・Column temperature: 40°C
・Developing solvent: tetrahydrofuran ・Flow rate: 1 mL/min

The evaluation method of the lubricating oil composition of each example and each comparative example is as follows.
[Friction test: coefficient of friction]
Using an MTM (Mini Traction Machine) tester manufactured by PCS Instruments, the coefficient of friction of the lubricating oil composition was measured under the following conditions.
(Measurement condition)
・Test method: Ball-on-disk ・Test piece: Standard test piece (AISI 52100 standard) disc and ball (3/4 inch in diameter) of the same material are used ・Test time: 2 hours ・Contact surface pressure: 1 GPa
・Measurement speed: 50mm/s
・Oil temperature: 135℃
・Slip ratio (SRR): 50%
・ Oil volume: 35 mL
[Corrosion test: Copper elution amount]
100 mL of the lubricating oil composition was placed as test oil in a glass test tube (diameter 40 mm x length 300 mm), and a copper plate (25 mm x 25 mm x 1 mm) was polished and immersed in the test oil to conduct a corrosion test. The test was conducted for 168 hours while blowing air at an oil temperature of 135° C. and a flow rate of 5 L/h. The results were evaluated by the elution amount of copper. The eluted amount of copper was measured according to JPI-5S-38-2003.

[Examples 1 and 2, Comparative Examples 1 to 5]
After preparing a lubricating oil composition by blending each component with the base oil so as to have the composition shown in Table 1 below, the lubricating oil composition of each example and each comparative example was evaluated according to the evaluation method. . The results obtained are shown in Table 1 below.

In addition, each component shown in following Table 1 represents the following compounds, respectively.
<Component (A): Base oil>
Hydrorefined base oil (mineral oil): API standard group III 100N base oil, 40°C kinematic viscosity 19.4 mm ² /s, 100°C kinematic viscosity 4.3 mm ² /s, viscosity index 126, sulfur content 0.0 001% by weight, 14% by weight NOACK evaporation, ndM ring analysis; % C _P 78.3, % C _A =0.1

<Component (B): Copolymer>
Copolymer (I): a structural unit represented by the following formula (a1-1) as the structural unit (a), a structural unit represented by the following formula (b1-1) as the structural unit (b), and a copolymer composed of a structural unit represented by the following formula (c1-1) as the structural unit (c). (Mass average molecular weight (Mw) = 25,000.)

式（ａ１－１）中、－Ｃ_３２Ｈ_６５及び－Ｃ_２６Ｈ_５３のアルキル基は、いずれも直鎖アルキル基である。

In formula (a1-1), the alkyl groups of —C ₃₂ H ₆₅ and —C ₂₆ H ₅₃ are both linear alkyl groups.

式（ｂ１－１）中、－Ｃ_５Ｈ_１０－及び－Ｃ_６Ｈ_１２－のアルキレン基は、いずれも直鎖のアルキレン基である。

In formula (b1-1), the alkylene groups of -C ₅ H ₁₀ - and -C ₆ H ₁₂ - are both linear alkylene groups.

式（ｃ１－１）中、－Ｃ_２Ｈ_４－は、エチレン基である。

In formula (c1-1), —C ₂ H ₄ — is an ethylene group.

Copolymerization (II): from a structural unit represented by the following formula (a1-1) as the structural unit (a) and a structural unit represented by the following formula (b1-2) as the structural unit (b) The copolymer composed. (Mass average molecular weight (Mw) = 25,000.)

式（ａ１－１）中、－Ｃ_３２Ｈ_６５及び－Ｃ_２６Ｈ_５３のアルキル基は、いずれも直鎖アルキル基である。

In formula (a1-1), the alkyl groups of —C ₃₂ H ₆₅ and —C ₂₆ H ₅₃ are both linear alkyl groups.

式（ｂ１－２）中、－Ｃ_５Ｈ_１０－及び－Ｃ_４Ｈ_８－のアルキレン基は、いずれも直鎖のアルキレン基である。

In formula (b1-2), the alkylene groups of -C ₅ H ₁₀ - and -C ₄ H ₈ - are both linear alkylene groups.

<Copolymer other than component (B)>
Copolymer (III): A structural unit represented by the following formula (d1-1), a structure represented by the following formula (e1-1), based on 100% by mass of the total amount of structural units constituting the copolymer A copolymer composed of a unit and a structural unit represented by the following formula (f1-1). (Mass average molecular weight (Mw) = 25,000.)

式（ｄ１－１）中、－Ｃ_２Ｈ_４－は、エチレン基である。

In formula (d1-1), —C ₂ H ₄ — is an ethylene group.

式（ｅ１－１）中、－Ｃ_２Ｈ_４－は、エチレン基である。

In formula (e1-1), —C ₂ H ₄ — is an ethylene group.

式（ｆ１－１）中、－Ｃ_１２Ｈ_２５のアルキル基は、直鎖アルキル基である。

In formula (f1-1), the alkyl group of —C ₁₂ H ₂₅ is a linear alkyl group.

<Friction modifier>
Molybdenum-based friction modifier: molybdenum dithiocarbamate “ADEKA SAKURALUBE (registered trademark) 525” (trade name, manufactured by ADEKA), molybdenum atom content 10.0% by mass, sulfur atom content 11.0% by mass
・Ester-based friction modifier: Glycerin monooleate ・Amine-based friction modifier: Diethanolamine

<Other ingredients>
· Calcium sulfonate: base value (perchloric acid method) 300 mgKOH / g, content of calcium atoms 11.9% by mass
Zinc dithiophosphate: zinc dialkyldithiophosphate, zinc atom content 8.9% by mass, phosphorus atom content 7.4% by mass, sulfur atom content 15.0% by mass
・Other additives

As shown in Table 1, the lubricating oil compositions of Examples 1 and 2 contain component (A) and component (B) as a friction modifier, so that the coefficient of friction at high temperatures is low and exhibits a high friction reducing effect. In addition, the copper elution amount was remarkably small, and it was confirmed that the copper corrosion prevention property was also excellent.
On the other hand, since the lubricating oil compositions described in Comparative Examples 1 to 5 use a component other than the component (B) as a friction modifier, both the friction reducing effect at high temperatures and the corrosion prevention against copper can be achieved. confirmed that it is not possible.

The lubricating oil composition, which is one embodiment of the present invention, can achieve both an excellent friction reducing effect and an excellent anti-corrosion property against copper even at high temperatures. Therefore, it can be used as a lubricating oil for internal combustion engines such as automobiles such as motorcycles and four-wheeled vehicles, gasoline engines such as generators and ships, diesel engines, and gas engines. It can be preferably used as a lubricating oil for lubricating between such parts, and more preferably as a lubricating oil for lubricating the internal combustion engine including members containing copper.
In addition, since the lubricating oil composition according to one embodiment of the present invention has an excellent friction-reducing effect at high temperatures even when no metallic friction modifier is used, metallic friction modifiers such as MoDTC Uses that require reduction of, for example, gasoline engines with strict environmental regulations, diesel engines, or lubricating oil compositions for internal combustion engines such as engines and gas engines fueled by dimethyl ether. .

Claims (13)

A base oil (A), a structural unit (a) derived from an alkyl (meth)acrylate having a branched alkyl group having 24 to 75 carbon atoms, and a structural unit (b) represented by the following general formula (b1): A lubricating oil composition containing a polymer (B).

(In general formula (b1), R ¹ represents a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ² represents a methyl group or a hydrogen atom. m and n each independently represent 1 to 10 is an integer, and r and s are each independently an integer from 1 to 30.) The component (B) further comprises one or more monomers selected from the group consisting of amino group-containing monomers, quaternary ammonium base-containing monomers, nitrile group-containing monomers and nitro group-containing monomers. 2. The lubricating oil composition according to claim 1, which is a copolymer containing a structural unit (c) derived from a polymer. 3. The content of the structural unit (a) in the component (B) is 40% by mass or more and 60% by mass or less based on 100% by mass of the total amount of the structural units of the component (B). The lubricating oil composition according to . The lubricating oil composition according to any one of claims 1 to 3, wherein the weight average molecular weight (Mw) of component (B) is 2,000 to 200,000. Furthermore, metallic detergents, antiwear agents, ashless dispersants, viscosity index improvers, extreme pressure agents, pour point depressants, antioxidants, antifoaming agents, surfactants, demulsifiers, friction modifiers, The lubricating oil composition according to any one of claims 1 to 4, containing at least one selected from the group consisting of oiliness improvers, rust inhibitors and metal deactivators. The lubricating oil composition according to any one of claims 1 to 5, wherein the content of phosphorus atoms is 0.10% by mass or less based on the total amount of the lubricating oil composition. The amino group-containing monomer is (meth)acrylic acid-N,N-dimethylaminoethyl ester, (meth)acrylic acid-N,N-diethylaminoethyl ester and (meth)acrylic acid-N,N-di- The lubricating oil composition according to any one of claims 2 to 6, which is one or more tertiary amino group-containing monomers selected from the group consisting of t-butylaminoethyl esters. Any one of claims 1 to 7, wherein the component (B) is a copolymer further comprising a structural unit (d) derived from a hydroxyalkyl (meth)acrylate represented by the following general formula (d1): The lubricating oil composition according to claim 1.

(In general formula (d1), R ⁴ represents a methyl group or a hydrogen atom, and R ⁵ represents an alkylene group having 2 to 4 carbon atoms.) The lubricating oil composition according to any one of claims 1 to 8, wherein the structural unit (b) is represented by the following general formula (b2).

(In general formula (b2), R ² represents a methyl group or a hydrogen atom, and R ³ represents a divalent hydrocarbon group having 2 to 8 carbon atoms.) The lubricating oil composition according to any one of claims 1 to 9, wherein the content of the component (B) is 0.1% by mass or more and 3.0% by mass or less based on the total amount of the lubricating oil composition. . The lubricating oil composition according to any one of claims 1 to 10, wherein the molybdenum atom content is 0.05% by mass or less based on the total amount of the lubricating oil composition. A base oil (A), a structural unit (a) derived from an alkyl (meth)acrylate having a branched alkyl group having 24 to 75 carbon atoms, and a structural unit (b) represented by the following general formula (b1): A method for producing a lubricating oil composition, comprising blending the polymer (B).

(In general formula (b1), R ¹ represents a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ² represents a methyl group or a hydrogen atom. m and n each independently represent 1 to 10 is an integer, and r and s are each independently an integer from 1 to 30.) A lubricating method, comprising using the lubricating oil composition according to any one of claims 1 to 11 for a member containing copper.