JP2023046286A - Lubricant friction reducing agent and lubricant composition - Google Patents

Abstract

To provide a lubricant friction reducing agent and a lubricant composition that are excellent in friction reducing effect.SOLUTION: A lubricant friction reducing agent comprises a (meth)acrylic copolymer A containing a structural unit derived from a macromonomer (a1) and a structural unit derived from an alkyl acrylate (a2) having an alkyl group having 1 to 4 carbon atoms, wherein the content of the structural unit derived from the macromonomer (a1) is 1 to 40 mass% with respect to 100 mass% of the (meth)acrylic copolymer A as a total mass.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a lubricating oil friction reducer and a lubricating oil composition for use in engine oils and the like.

Lubricating oils used as metalworking oils, engine oils, drive system oils, hydraulic oils, etc. contain various friction reducing agents for the purpose of extending the life of equipment by preventing seizure and improving fuel efficiency by reducing friction loss. It is Friction reducers include oiliness improvers such as long-chain fatty acid esters and fatty acid amides, antiwear agents such as phosphate esters and zinc dithiophosphate, extreme pressure agents such as organic sulfur compounds and organic halogen compounds, and organic molybdenum compounds. However, depending on the usage conditions and usage environment, there is a problem that the effect of reducing friction with these additives alone is insufficient. In order to overcome this problem, studies are underway to use polymer materials as friction modifiers. It is disclosed that comb polymers containing units are suitable for use as friction modifiers.

WO2007/003238

However, the method described in Patent Document 1 is insufficient in the effect of reducing friction.

An object of the present invention is to provide a friction modifier for lubricating oil and a lubricating oil composition which are excellent in friction-reducing effect.

The present invention has the following aspects.
[1] A (meth)acrylic copolymer A containing a structural unit derived from the macromonomer (a1) and a structural unit derived from an alkyl acrylate (a2) having an alkyl group having 1 to 4 carbon atoms, ) A friction modifier for lubricating oil, wherein the content of the structural unit derived from the macromonomer (a1) is 1 to 40% by mass with respect to 100% by mass of the total mass of the acrylic copolymer A.
[2] The friction modifier for lubricating oil according to [1], wherein the (meth)acrylic copolymer A further contains a structural unit derived from an alkyl acrylate (a3) having 5 to 30 carbon atoms.
[3] The friction modifier for lubricating oil according to [1] or [2], wherein the macromonomer (a1) contains a constitutional unit derived from a vinyl-based radically polymerizable monomer m.
[4] The friction modifier for lubricating oil according to [3], wherein the vinyl-based radically polymerizable monomer m contains an alkyl methacrylate m _L having an alkyl group with 5 to 30 carbon atoms.
[5] The friction modifier for lubricating oil according to any one of [1] to [4], wherein the macromonomer (a1) has the structure of the following formula (1).

(Wherein, X ¹ to X ^n-1 each independently represent a hydrogen atom, a methyl group or CH ₂ OH, Y ¹ to Y ⁿ each independently represent a monomer of the macromonomer (a1) A substituent other than X ¹ to X ^n-1 bonded to the vinyl group of component m, which is a structural unit, Z represents a terminal group, and n represents an integer of 2 to 10,000.)
[6] Lubrication according to any one of [1] to [5], wherein the (meth)acrylic copolymer A contains a structural unit derived from (meth)acrylate (a4) represented by the following general formula (2) Friction reducer for oil.

(In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² represents a hydrogen atom or an organic group containing a polar group.)
[7] A lubricating oil composition containing the friction modifier for lubricating oil according to any one of [1] to [6].

According to the friction modifier for lubricating oil of the present invention, it is possible to provide a friction modifier and a lubricating oil composition having a high friction-reducing effect.

The present invention will be described in detail below. The following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention only to these embodiments. The present invention can be implemented in various forms without departing from its spirit.

In the present invention, "(meth)acryl" is a generic term for "acryl" and "methacryl". "(Meth)acrylate" is a generic term for "acrylate" and "methacrylate". "(Meth)acryloyl group" is a generic term for "acryloyl group" and "methacryloyl group", and is a group represented by CH ₂ =C(R)-C(=O)- (R is a hydrogen atom or a methyl group) is. A "macromonomer" means a polymer having a radically polymerizable group or an addition-reactive functional group. A "vinyl-based radically polymerizable monomer" means a monomer having an ethylenically unsaturated bond that is not a macromonomer.

The friction modifier for lubricating oil of the present invention contains a (meth)acrylic copolymer A.
The (meth)acrylic copolymer A means a copolymer in which at least a part of the structural units is a structural unit derived from a (meth)acrylic monomer. The (meth)acrylic copolymer may further contain structural units derived from monomers other than the (meth)acrylic monomer (for example, styrene).

The (meth)acrylic copolymer A is a copolymer containing structural units derived from the macromonomer (a1) and structural units derived from the alkyl acrylate (a2) having an alkyl group having 1 to 4 carbon atoms.
The macromonomer (a1) is not particularly limited as long as it is a compound having a radically polymerizable group and a repeating structure. Compounds containing two or more constitutional units derived from the monomer m having a vinyl-based radically polymerizable group and having a radically polymerizable group at the terminal thereof, and the like can be mentioned. A compound containing two or more constitutional units derived from the monomer m having a vinyl-based radically polymerizable group and having a radically polymerizable group at the end thereof is preferred because of its high degree of design with respect to the solubility in the base oil. Two or more macromonomers (a1) may be used in combination.

Examples of the monomer m include styrene, vinyl acetate, and (meth)acrylate compounds. Examples of (meth)acrylate compounds include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl ( meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, n-decyl (meth) acrylate, n-undecyl (meth) acrylate, n-dodecyl (meth) Linear alkyl groups such as acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, n-cetyl (meth) acrylate, n-stearyl (meth) acrylate, n-behenyl (meth) acrylate, (meth)acrylates having; i-propyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, s-butyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth) Acrylate, i-nonyl (meth)acrylate, i-decyl (meth)acrylate, 3-i-propylheptyl (meth)acrylate, i-undecyl (meth)acrylate, 2-t-butylheptyl (meth)acrylate, i- (Meth)acrylates having branched alkyl groups such as dodecyl (meth)acrylate, i-tridecyl (meth)acrylate, i-tetradecyl (meth)acrylate; cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate; ) acrylates, dicyclopentenyl (meth)acrylates, dicyclopentenoxyethyl (meth)acrylates, dicyclopentanyl (meth)acrylates, adamantyl (meth)acrylates having a cyclic alkyl group (meth)acrylates;2 - hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, glycerin mono (meth)acrylate , ethylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate having a hydroxyl group (meth) acrylate; (meth) acrylic acid, 2- (meth) acryloyloxyethyl succinate, 2- (meth) maleate (Meth)acrylates containing a carboxy group such as acryloyloxyethyl, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate; phenyl (meth)acrylate, benzyl (meth)acrylate , phenoxyethyl (meth)acrylate, phenoxydiethyleneglycol (meth)acrylate, phenoxypolyethyleneglycol (meth)acrylate, nonylphenoxypolyethyleneglycol (meth)acrylate, phenoxypolypropyleneglycol (meth)acrylate, phenylphenyl (meth)acrylate, phenylphenoxyethyl (Meth)acrylates having an aromatic ring structure such as (meth)acrylate, phenoxybenzyl (meth)acrylate, phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, (1-naphthyl)methyl (meth)acrylate; tetrahydrofurfuryl (Meth)acrylates having a heterocyclic structure such as (meth)acrylate, glycidyl (meth)acrylate, (meth)acryleoylmorpholine; methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate Alkoxy(meth)acrylates such as acrylate; 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, trifluoroethyl (meth) ) acrylate, heptadecafluorodecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, (meth)acrylamide and the like. These may be used in combination of two or more.

Since the monomer m has excellent solubility in the base oil, linear, branched or cyclic alkyl methacrylate having 5 to 30 carbon atoms (hereinafter also referred to as "monomer m _L " ), more preferably linear, branched or cyclic alkyl methacrylate having 8 to 18 carbon atoms, linear, branched or cyclic alkyl having 12 to 14 carbon atoms More preferably, it contains methacrylate. Examples of the monomer _mL include n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, n-nonyl methacrylate, n-decyl methacrylate, n-undecyl methacrylate, n-dodecyl Methacrylates having linear alkyl groups such as methacrylate, n-tridecyl methacrylate, n-tetradecyl methacrylate, cetyl methacrylate, stearyl methacrylate, and behenyl methacrylate; i-amyl methacrylate, 2-ethylhexyl methacrylate, i-nonyl methacrylate, i -Branched alkyl groups such as decyl methacrylate, 3-i-propylheptyl methacrylate, i-undecyl methacrylate, 2-t-butylheptyl methacrylate, i-dodecyl methacrylate, i-tridecyl methacrylate, and i-tetradecyl methacrylate methacrylates having a cyclic alkyl group such as cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenoxyethyl methacrylate, dicyclopentanyl methacrylate and adamantyl methacrylate. These may be used in combination of two or more.

The monomer m preferably contains a linear or branched alkyl methacrylate having 1 to 4 carbon atoms (hereinafter also referred to as “monomer m _S ”), and has 1 to 3 carbon atoms. more preferably contains a linear or branched alkyl methacrylate having 1 or 2 carbon atoms. Examples of the monomer _mS include methacrylates having linear alkyl groups such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate; i-propyl methacrylate, i-butyl methacrylate, t- Examples include methacrylates having branched alkyl groups such as butyl methacrylate and s-butyl methacrylate.

Further, the macromonomer (a1) preferably has a structure represented by the following formula (1) from the viewpoint of radical polymerizability.

(Wherein, X ¹ to X ^n-1 each independently represent a hydrogen atom, a methyl group or CH ₂ OH, Y ¹ to Y ⁿ each independently represent a monomer of the macromonomer (a1) A substituent other than X ¹ to X ^n-1 bonded to the vinyl group of component (m), which is a structural unit, Z represents a terminal group, and n represents an integer of 2 to 10,000.)

X ¹ to X ^n-1 and Y ¹ to Y ⁿ are each independently a substituent that bonds to the vinyl group of component (m). Y ¹ to Y ⁿ are, for example, OR ¹ , halogen atom, COR ² , COOR ³ , CN, CONR ⁴ R ⁵ , NHCOR ⁶ or R ⁷ , and each of R ¹ to R ⁷ independently represents a hydrogen atom, It represents an alkyl group, an aryl group, a heteroaryl group, and the like.

In the formula, X ¹ to X ^n-1 are each independently preferably a hydrogen atom or a methyl group, more preferably a methyl group.
Y ¹ to Y ⁿ are each independently preferably COR ² , COOR ³ , CN or CONR ⁴ R ⁵ , more preferably COOR ³ .
R ¹ to R ⁷ are each independently preferably an alkyl group, more preferably a straight-chain or branched-chain alkyl group, and even more preferably a straight-chain alkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 30 carbon atoms, more preferably 1 to 25 carbon atoms, and even more preferably 1 to 20 carbon atoms.

The terminal group Z includes a group derived from a hydrogen atom and a radical polymerization initiator, similarly to the terminal groups of polymers obtained by known radical polymerization.

When the macromonomer (a1) contains structural units derived from the monomer _mL , the content of the structural units derived from the monomer _mL is 80 mass with respect to the total mass of the macromonomer (a1). % or more, more preferably 80 to 100 mass %, still more preferably 90 to 100 mass %, and particularly preferably 95 mass % or more and less than 100 mass %.

When the macromonomer (a1) contains a structural unit derived from the monomer _mS , the content of the structural unit derived from the monomer _mS is 20 mass with respect to the total mass of the macromonomer (a1). % or less, more preferably 0 mass % or more and 15 mass % or less, more preferably 0 mass % or more and 10 mass % or less, and particularly preferably 0 mass % or less and 5 mass % or less.

When the macromonomer (a1) contains both structural units derived from the monomer m _L and structural units derived from the monomer m _S , [content of structural units derived from the monomer m _S ]/[ The content of structural units derived from the monomer _mL ] is preferably 0.001 to 0.1, more preferably 0.01 to 0.05, and further preferably 0.015 to 0.03. preferable.

In addition, the solubility in the base oil and the friction reduction performance can be improved, and the fuel efficiency can be improved by lowering the viscosity of the lubricating oil composition. The content of the structural unit derived from the macromonomer (a1) is preferably 1% by mass or more and 40% by mass or less, more preferably 3% by mass or more and 35% by mass or less, and further 5% by mass or more and 30% by mass or less. preferable.

The solubility in base oil and friction reduction performance can be improved, and the fuel efficiency can be improved by lowering the viscosity of the lubricating oil composition, so the mass average molecular weight measured by gel permeation chromatography of the macromonomer (a1) (Mw) is preferably 5,000 to 100,000, more preferably 7,000 to 80,000, even more preferably 9,000 to 60,000, and particularly preferably 10,000 to 50,000.

The number average molecular weight of the macromonomer (a1) measured by gel permeation chromatography can improve the solubility in the base oil and the friction reduction performance, and the fuel efficiency can be improved by reducing the viscosity of the lubricating oil composition. (Mn) is preferably 500 to 30,000, more preferably 1,000 to 25,000, particularly preferably 2,000 to 20,000, and most preferably 3,000 to 16,000.

The solubility in the base oil and the friction reduction performance can be improved, and the fuel efficiency can be improved by reducing the viscosity of the lubricating oil composition, so the molecular weight distribution of the macromonomer (a1) measured by gel permeation chromatography ( Mw/Mn) is preferably 1.0 to 5.0, more preferably 1.3 to 3.0, even more preferably 1.5 to 2.5.

As the macromonomer (a1), one produced by a known method may be used, or a commercially available one may be used. Examples of the method for producing the macromonomer (a1) include a method using a cobalt chain transfer agent (US Pat. No. 4,680,352), and an α-substituted unsaturated compound such as α-bromomethylstyrene as a chain transfer agent. (International Publication No. 88/04304), a method of chemically bonding a polymerizable group (JP-A-60-133007 and US Pat. No. 5,147,952) and a method by thermal decomposition (JP-A-11-240854) publication).

A production method using a cobalt chain transfer agent is preferable in that the number of production steps is small and a catalyst with a high chain transfer constant is used. Since the cobalt chain transfer agent has a high chain transfer constant, a macromonomer with a controlled molecular weight can be obtained by adding a small amount.

A known cobalt complex can be used as the cobalt chain transfer agent. The amount of the cobalt chain transfer agent is preferably 0.00001 to 0.1 parts by mass, more preferably 0.00005 to 0.05 parts by mass, with respect to 100 parts by mass of the vinyl radically polymerizable monomer m. is more preferable, and 0.0001 to 0.02 parts by mass is particularly preferable.

Examples of the alkyl acrylate (a2) having 1 to 4 carbon atoms in the alkyl group include acrylates having a linear alkyl group such as methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate; i- Examples include acrylates having branched alkyl groups such as propyl acrylate, i-butyl acrylate, t-butyl acrylate and s-butyl acrylate. These may be used in combination of two or more. Alkyl acrylates having 2 to 4 carbon atoms are preferred, alkyl acrylates having 3 to 4 carbon atoms are more preferred, and alkyl acrylates having 4 carbon atoms are even more preferred, because they are excellent in solubility in base oil and friction-reducing effect.

The solubility in the base oil and the friction reduction performance can be improved, and the fuel efficiency can be improved by reducing the viscosity of the lubricating oil composition. The content of the structural unit derived from the alkyl acrylate (a2) is preferably 1% by mass or more and 70% by mass or less, more preferably 5% by mass or more and 65% by mass or less, and further preferably 10% by mass or more and 60% by mass or less. 15% by mass or more and 60% by mass or less is particularly preferable.

Since the solubility of the (meth)acrylic copolymer A in the base oil can be improved, an alkyl acrylate (a3) having an alkyl group having 5 to 30 carbon atoms (hereinafter simply referred to as "alkyl acrylate (a3)”) is preferably further contained. Examples of the alkyl acrylate (a3) include n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-undecyl acrylate and n-dodecyl. acrylate, n-tridecyl acrylate, n-tetradecyl acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, acrylate having a linear alkyl group such as behenyl (meth) acrylate; i-amyl acrylate, 2- Ethylhexyl acrylate, i-nonyl acrylate, i-decyl acrylate, 3-i-propylheptyl acrylate, i-undecyl acrylate, 2-t-butylheptyl acrylate, i-dodecyl acrylate, i-tridecyl acrylate, i-tetradecyl Acrylate having branched alkyl group such as acrylate; Cyclic alkyl group such as cyclopentyl acrylate, cyclohexyl acrylate, isobornyl acrylate, dicyclopentenyl acrylate, dicyclopentenoxyethyl acrylate, dicyclopentanyl acrylate, adamantyl acrylate, etc. and acrylates having These may be used in combination of two or more.
Linear or branched alkyl acrylates having 8 to 18 carbon atoms are preferred because they are highly soluble in base oil and effective in reducing friction, and linear or branched alkyl acrylates having 12 to 14 carbon atoms are preferred. More preferred.

In addition, the solubility in the base oil and the friction reduction performance can be improved, and the fuel efficiency can be improved by lowering the viscosity of the lubricating oil composition. , the content of the structural unit derived from the alkyl acrylate (a3) is preferably 5% by mass or more and 80% by mass or less, more preferably 10% by mass or more and 75% by mass or less, and further preferably 15% by mass or more and 70% by mass or less; 15% by mass or more and 60% by mass or less is particularly preferable.

When the alkyl acrylate (a3) is contained, the total content of the components (a1) to (a3) is preferably 50% by mass or more with respect to the total mass of the (meth)acrylic copolymer A, It is more preferably 70% by mass or more, and even more preferably 90% by mass or more. The total amount of structural units derived from the components (a1) to (a3) does not exceed 100% by mass with respect to the total mass of the (meth)acrylic copolymer A.

The friction reduction performance of the (meth)acrylic copolymer A can be improved, and the fuel efficiency can be improved by reducing the viscosity of the lubricating oil composition. Therefore, the (meth)acrylic copolymer A is It is preferable to further include a structural unit derived from (meth)acrylate (a4) represented by the following general formula (2) (hereinafter, the (meth)acrylate (a4) represented by the following general formula (2) is referred to as a "polar group Also referred to as "contained (meth)acrylate (a4)").

(In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² represents a hydrogen atom or an organic group containing a polar group.)
Polar groups include, for example, hydroxyl group, carboxy group, heterocyclic structure (e.g., aliphatic heterocyclic ring having 2 to 6 carbon atoms, aromatic heterocyclic ring having 4 to 10 carbon atoms), alkoxy group, and C 3 to 9 A trialkoxysilyl group, a phosphate group, an amino group, a primary amino group having 1 to 6 carbon atoms, a secondary amino group having 2 to 6 carbon atoms, and the like. Examples of the component (a4) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl. (Meth) acrylates having hydroxyl groups such as (meth) acrylates, glycerin mono (meth) acrylates, polyethylene glycol mono (meth) acrylates, polypropylene glycol mono (meth) acrylates; (meth) acrylic acid, succinic acid 2-(meth) (meth)acrylates containing a carboxy group such as acryloyloxyethyl, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate; (meth)acrylates having a heterocyclic structure such as tetrahydrofurfuryl (meth)acrylate and glycidyl (meth)acrylate; alkoxy groups such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate and butoxyethyl (meth)acrylate 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, dimethylaminoethyl (meth)acrylate , diethylaminoethyl (meth)acrylate, (meth)acrylamide, and the like. These may be used in combination of two or more. The polar group-containing (meth)acrylate (a4) is preferably a (meth)acrylate having a hydroxyl group or a carboxy group, more preferably a (meth)acrylate having a hydroxyl group, and still more preferably an acrylate having a hydroxyl group. The total number of carbon atoms in the polar group-containing (meth)acrylate (a4) is preferably 3-10, more preferably 3-9, even more preferably 3-8.

When the polar group-containing (meth)acrylate (a4) is contained, since the friction reducing effect is excellent, the polar group-containing (meth)acrylate ( The content of the structural unit derived from a4) is preferably 0.01% by mass or more and 30% by mass or less, more preferably 0.1% by mass or more and 20% by mass or less, and further 0.5% by mass or more and 10% by mass or less. preferable.

The (meth)acrylic copolymer A may contain other radically polymerizable vinyl compounds other than the components (a1) to (a4) as constitutional units. Other radically polymerizable vinyl compounds include, for example, styrene, α-methylstyrene, pt-butylstyrene, vinyltoluene, vinyl acetate, and (meth)acrylate compounds other than components (a2) to (a4). mentioned.

(Meth)acrylate compounds other than components (a2) to (a4) include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n -octyl methacrylate, n-nonyl methacrylate, n-decyl methacrylate, n-undecyl methacrylate, n-dodecyl methacrylate, n-tridecyl methacrylate, n-tetradecyl methacrylate, n-cetyl methacrylate, n-stearyl methacrylate, n-behenyl Methacrylates having a linear alkyl group such as methacrylate; i-propyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, s-butyl methacrylate, isoamyl methacrylate, 2-ethylhexyl methacrylate, i-nonyl methacrylate, i-decyl methacrylate , 3-i-propylheptyl methacrylate, i-undecyl methacrylate, 2-t-butylheptyl methacrylate, i-dodecyl methacrylate, i-tridecyl methacrylate, i-tetradecyl methacrylate and other methacrylates having branched alkyl groups; Methacrylates having a cyclic alkyl group such as cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenoxyethyl methacrylate, dicyclopentanyl methacrylate, and adamantyl methacrylate; phenyl (meth)acrylate, benzyl ( meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, nonylphenoxy polyethylene glycol (meth) acrylate, phenoxy polypropylene glycol (meth) acrylate, phenylphenyl (meth) acrylate, (meth)acrylates having an aromatic ring structure such as phenylphenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, (1-naphthyl)methyl (meth)acrylate, trifluoroethyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate and the like. These may be used in combination of two or more.

In addition, the mass average molecular weight (Mw) of the (meth)acrylic copolymer A of the present invention measured by gel permeation chromatography (GPC) can provide good solubility in base oil and friction reduction performance, It is preferably 10,000 or more and 1,000,000 or less, more preferably 30,000 or more and 500,000 or less, and even more preferably 50,000 or more and 300,000 or less, because the low viscosity of the composition can improve fuel economy.

In addition, the number average molecular weight (Mn) of the (meth)acrylic copolymer A of the present invention measured by gel permeation chromatography (GPC) can improve the solubility in base oil and the friction reducing performance, and the lubricating oil It is preferably 5,000 or more and 100,000 or less, more preferably 10,000 or more and 80,000 or less, and even more preferably 15,000 or more and 50,000 or less, because the low viscosity of the composition can improve fuel economy.

In addition, the molecular weight distribution (Mw/Mn) of the (meth)acrylic copolymer A of the present invention measured by gel permeation chromatography (GPC) shows good solubility in base oil and friction-reducing performance. Since fuel efficiency can be improved by lowering the viscosity of the oil composition, it is preferably 1.0 to 30, more preferably 2.0 to 25, and even more preferably 3.0 to 10. .

Next, an example of the method for producing the friction modifier for lubricating oil of the present invention will be shown.
The friction modifier for lubricating oil of the present invention is a monomer containing the macromonomer (a1), the alkyl acrylate (a2), the alkyl acrylate (a3) and the other radically polymerizable vinyl compound in the base oil. Mixtures can be prepared by polymerization in known manner.
The base oil is not particularly limited, but API standard Group III base oils such as YUBASE3 manufactured by SK Lubricants, API standard Group III plus base oils such as YUBASE4 manufactured by SK Lubricants, and API standard Group IV base oils such as polyalphaolefins. etc.

The macromonomer (a1) is preferably a macromonomer obtained by polymerizing a monomer mixture containing a vinyl-based radically polymerizable monomer in the base oil using a cobalt chain transfer agent. Since the cobalt chain transfer agent has a high chain transfer constant, a macromonomer with a controlled molecular weight can be obtained by adding a small amount.
Polymerization may be carried out under known conditions, but it is preferable to use α-methylstyrene dimer as the chain transfer agent because it is particularly effective in suppressing heat generation during polymerization.

Friction modifiers for lubricating oils containing the (meth)acrylic copolymer A of the present invention are lubricating oils such as metal working oils, engine oils, gear oils, and hydraulic oils used in mobility such as industrial machinery, robots, and automobiles. It can be used as a friction reducer for lubricating oils added to.
Examples of base oils such as engine oils, gear oils, and hydraulic oils include mineral base oils refined from crude oil and chemically synthesized synthetic oils. , API standard Group III plus base oils such as YUBASE4 manufactured by SK Lubricants, and API standard Group IV base oils such as polyalphaolefins.

A base oil solution containing 2% by mass of (meth)acrylic copolymer is prepared, and a fully automatic simple dynamic viscometer (manufactured by Cannon, trade name: Simple-VIS type) is used in accordance with the ASTM D7279 (D445) method. The kinematic viscosity (Vk40) measured at 40° C. using the liquid is preferably 30 cSt or less, more preferably 25 cSt or less, and even more preferably 22.5 cSt or less.

A base oil solution containing 2% by mass of a (meth)acrylic copolymer is prepared, and the coefficient of friction measured at 40°C using an SRV5 tester (manufactured by Optimol Instruments Pruftechnik GmbH) is preferably 0.18 or less. , is more preferably 0.17 or less, and even more preferably 0.16 or less.

The lubricating oil composition of the present invention is obtained by blending the friction reducing agent for lubricating oil of the present invention with a base oil. The lubricating oil composition of the present invention may contain additives other than the friction modifier for lubricating oil of the present invention. Other additives include antioxidants, viscosity index improvers, pour point depressants, detergent dispersants, corrosion inhibitors, rust inhibitors, defoamers, emulsifiers, fungicides, demulsifiers, and the like. In addition, friction reducing agents other than those of the present invention include oiliness improvers such as long-chain fatty acid esters and fatty acid amides, anti-wear agents such as phosphate esters and zinc dithiophosphate, and extreme pressure agents such as organic sulfur compounds and organic halogen compounds. , a friction modifier such as an organic molybdenum compound, and the like.
Also, the lubricating oil composition of the present invention may be a grease containing a thickener. Examples of the thickener include soap-based (lithium soap, calcium soap, sodium soap, aluminum soap, etc.), inorganic (bentonite, silica gel, etc.), organic (polyurea, polyurethane, etc.), and the like.

The content of the lubricating oil friction reducing agent of the present invention contained in the lubricating oil composition is preferably 0.01 to 30% by mass, and 0.01 to 30% by mass when the total mass of the lubricating oil composition is 100% by mass. 05 to 25% by mass is more preferable, and 0.1 to 20% by mass is even more preferable. When the content of the friction reducing agent for lubricating oil is 0.01% by mass or more, the friction reducing effect of the lubricating oil composition is improved, and when it is 30% by mass or less, the kinematic viscosity at low temperature of the lubricating oil composition is reduced and fuel efficiency is improved.

The present invention will be described in more detail below with reference to examples and comparative examples. In Tables 1 to 3, the content of structural units derived from each monomer is shown in % by mass. The content of each structural unit was calculated from the mass of the monomers with respect to the total mass of the monomers used in the polymerization reaction. It was evaluated by the following methods.

<Molecular Weight of Macromonomer (a1)>
It was measured using gel permeation chromatography (GPC) (HLC-8320 manufactured by Tosoh Corporation). After adjusting 0.2% by mass of a tetrahydrofuran solution of the macromonomer (a1), columns manufactured by Tosoh Corporation (TSKgel SuperHZM-M (inner diameter 4.6 mm, length 15 cm), HZM-M (inner diameter 4.6 mm, length 15 cm ), HZ-2000 (inner diameter 4.6 mm, length 15 cm), and TSKguardcolumn SuperHZ-L (inner diameter 4.6 mm, length 3.5 cm). Measurement was performed under the conditions of 35 ml/min, eluent: tetrahydrofuran (stabilizer BHT), column temperature: 40° C., and Mw and Mn were calculated in terms of standard polystyrene.

<Molecular weight of (meth)acrylic copolymer A>
It was measured using gel permeation chromatography (GPC) (HLC-8320 manufactured by Tosoh Corporation). After adjusting 0.2% by mass of a tetrahydrofuran solution of (meth)acrylic copolymer A obtained in the example, Tosoh Corporation columns (TSKgelSuperHZM-H 2 (inner diameter 6.0 mm, length 15 cm), TSKguardcolumn SuperHZ 10 μl of the above solution was injected into the device equipped with -H (inner diameter 4.6 mm, length 3.5 cm), flow rate 0.5 ml/min, eluent: tetrahydrofuran (stabilizer BHT), column temperature: 40 ° C. and calculated mass average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw/Mn) in terms of standard polystyrene.

<Kinematic viscosity at 40°C (Vk40)>
A YUBASE4 solution containing 2% by mass of the obtained (meth)acrylic copolymer was prepared, and in accordance with the ASTM D7279 (D445) method, a fully automatic simple dynamic viscometer (manufactured by Cannon, trade name: Simple-VIS type) was used to evaluate kinematic viscosity at 40°C.

<Friction coefficient at 40°C>
A YUBASE4 solution containing 2% by mass of the obtained (meth)acrylic copolymer was prepared, and the friction coefficient at 40° C. was measured using an SRV5 tester (manufactured by Optimol Instruments Pruftechnik GmbH). The measurement conditions were as follows, and the friction coefficient was evaluated 30 minutes after the start of measurement.
・Test method: Ball-on-disk (diameter of ball: 10 mm, material of ball and disk: SUJ2)
・Test mode: reciprocating (50Hz, stroke 1mm)
・Load: 200N

[Production Example 1]
(Synthesis of Co complex (cobalt chain transfer agent))
In a synthesizer equipped with a stirrer, 2.00 g (8.03 mmol) of cobalt (II) acetate tetrahydrate (manufactured by Wako Pure Chemical Industries, Ltd., Wako special grade) and diphenylglyoxime (Tokyo Chemical Industry Co., Ltd.) were placed under a nitrogen atmosphere. 3.86 g (16.1 mmol) of EP grade) and 100 ml of diethyl ether previously deoxygenated by nitrogen bubbling were added and stirred at 25° C. for 2 hours.
Next, 20 ml of boron trifluoride diethyl ether complex (manufactured by Tokyo Chemical Industry Co., Ltd., EP grade) was added, and the mixture was further stirred for 6 hours. The resulting product was filtered, and the solid was washed with diethyl ether and dried at 100 MPa or less at 20° C. for 12 hours to obtain 5.02 g (7.93 mmol, yield 99% by mass) of Co complex as a brown solid. .

[Production Example 2]
(Synthesis of macromonomer M1)
In a reaction vessel equipped with a stirrer, a cooling pipe and a thermometer, 58 parts of YUBASE4, Acryester SL (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester SL, an alkyl methacrylate having 12 carbon atoms in the alkyl group, and an alkyl group 98 parts of a mixture of alkyl methacrylates having 13 carbon atoms), 2 parts of methyl methacrylate (MMA), and 0.005 parts of the Co complex prepared in Production Example 1 are added, and the liquid temperature is raised to 40 ° C. and stirred. Nitrogen was bubbled for 2 hours to remove dissolved oxygen. A mixed liquid consisting of YUBASE4 (2 parts) and 0.1 part of t-butylperoxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 26), which is a polymerization initiator, is added and the liquid temperature is adjusted. After raising the temperature to 90° C. and stirring for 2.5 hours, a mixture of YUBASE4 (10 parts) and Luperox 26 (0.7 parts) was added dropwise over 1 hour. After dropping, the temperature was raised to 105° C. and maintained for 1.5 hours, then 20 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M1. Table 1 shows the results of GPC of the obtained macromonomer M1.

[Production Example 3]
(Synthesis of macromonomer M2)
58 parts of YUBASE4, 98 parts of Acryester SL, 2 parts of MMA, and 0.005 parts of the Co complex prepared in Production Example 1 were added to a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, and the liquid temperature was adjusted to 40. C. and nitrogen was bubbled for 2 hours while stirring to remove dissolved oxygen. A mixed liquid consisting of YUBASE4 (2 parts) and 0.1 part of t-amylperoxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 575) as a polymerization initiator was introduced and the liquid temperature was raised to 90. C. and stirred for 2.5 hours, a mixture of YUBASE4 (10 parts) and Luperox 26 (0.7 parts) was added dropwise over 1 hour. After dropping, the temperature was raised to 105° C. and maintained for 1.5 hours, then 20 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M2. Table 1 shows the results of GPC of the obtained macromonomer M2.

[Production Example 4]
(Synthesis of macromonomer M3)
38 parts of YUBASE4, 98 parts of Acrylester SL, 2 parts of MMA, and 0.003 parts of the Co complex prepared in Production Example 1 were added to a reaction vessel equipped with a stirrer, a cooling pipe, and a thermometer, and the liquid temperature was adjusted to 40. C. and nitrogen was bubbled for 2 hours while stirring to remove dissolved oxygen. A mixed liquid consisting of YUBASE4 (2 parts) and Luperox 26 (0.1 parts) was added, the liquid temperature was raised to 90 ° C., and after stirring for 2.5 hours, YUBASE4 (20 parts) and Luperox 26 (0.1 part) were added. .7 parts) was added dropwise over 1 hour. After dropping, the temperature was raised to 105° C. and maintained for 1.5 hours, then 30 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M3. Table 1 shows the results of GPC of the obtained macromonomer M3.

[Production Example 5]
(Synthesis of macromonomer M4)
In a reaction vessel equipped with a stirrer, a cooling pipe and a thermometer, 58 parts of YUBASE4, 98 parts of stearyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester S), 2 parts of MMA, Co prepared in Production Example 1 0.005 parts of the complex was added, the liquid temperature was raised to 40° C., and nitrogen was bubbled for 2 hours while stirring to remove dissolved oxygen. A mixed liquid consisting of YUBASE4 (2 parts) and Luperox 575 (0.1 parts) was added, the liquid temperature was raised to 90 ° C., and after stirring for 2.5 hours, YUBASE4 (10 parts) and Luperox 26 (0.1 parts) were added. .7 parts) was added dropwise over 1 hour. After dropping, the temperature was raised to 105° C. and maintained for 1.5 hours, then 20 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M4. Table 1 shows the results of GPC of the obtained macromonomer M4.

<Example 1>
In a reaction vessel equipped with a stirrer, a cooling pipe and a thermometer, 50 parts of YUBASE4, 47.6 parts of YUBASE4 solution of macromonomer M1 obtained in Production Example 2, n-butyl acrylate (Mitsubishi Chemical Co., trade name : nBA) 56 parts, 19 parts of lauryl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., trade name: LA), t-butyl peroxy-2-ethylhexanoate as a polymerization initiator (manufactured by NOF Corporation, trade name: 0.03 parts of Perbutyl O) and 0.2 parts of α-methylstyrene dimer (manufactured by NOF Corporation, trade name: Nofmer MSD) as a chain transfer agent were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. . After the liquid temperature was raised to 85° C. and held for 3.5 hours, a mixed liquid consisting of YUBASE4 (42 parts) and Perbutyl O (0.015 parts) was added dropwise over 2 hours. Furthermore, after holding at 85 ° C. for 1 hour, YUBASE4 (30 parts) and 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perocta O) ( 0.5 parts) was added dropwise over 1 hour. Thereafter, the temperature was raised to 110° C. and maintained for 1 hour, then 41.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 2 shows the evaluation results of the obtained friction modifier for lubricating oil. In Tables 2 and 3, the monomer composition also includes structural units in the macromonomer (a1).

<Example 2>
30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85° C., and a mixed liquid consisting of YUBASE4 (25 parts), nBA (13 parts), LA (62 parts), Luperox 575 (0.1 parts), and Nofmer MSD (0.2 parts) was added. It was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 2 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 3>
50 parts of YUBASE4 and 9.5 parts of YUBASE4 solution of macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85 ° C., and a mixed liquid consisting of YUBASE4 (25 parts), nBA (71 parts), LA (24 parts), Luperox 575 (0.1 parts), and Nofmer MSD (0.9 parts) was added. It was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (56.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 2 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 4>
30 parts of YUBASE4 and 19 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 were added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen was removed by bubbling nitrogen while stirring. . The liquid temperature was raised to 85 ° C., and a mixed liquid consisting of YUBASE4 (25 parts), nBA (68 parts), LA (22 parts), Luperox 575 (0.1 parts), and Nofmer MSD (0.9 parts) was added. It was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (71.6 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 2 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 5>
20 parts of YUBASE4 and 66.6 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85° C., and a mixed liquid consisting of YUBASE4 (25 parts), nBA (49 parts), LA (16 parts), Luperox 575 (0.1 parts), and Nofmer MSD (0.3 parts) was added. It was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.9 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 2 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 6>
30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85 ° C., and a mixed liquid consisting of YUBASE4 (25 parts), nBA (56 parts), LA (19 parts), Luperox 575 (0.1 parts), and Nofmer MSD (0.9 parts) was added. It was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 2 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 7>
30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of the macromonomer M2 obtained in Production Example 3 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85 ° C., and a mixed liquid consisting of YUBASE4 (25 parts), nBA (56 parts), LA (19 parts), Luperox 575 (0.1 parts), and Nofmer MSD (0.9 parts) was added. It was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 2 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 8>
In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 50 parts of YUBASE4, 47.6 parts of YUBASE4 solution of macromonomer M1 obtained in Production Example 2, 45 parts of nBA, 30 parts of LA, Perbutyl O and 0.3 part of Nofmer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. After the liquid temperature was raised to 85° C. and held for 3.5 hours, a mixed liquid consisting of YUBASE4 (42 parts) and Perbutyl O (0.015 parts) was added dropwise over 2 hours. Furthermore, after holding at 85° C. for 1 hour, a mixed liquid consisting of YUBASE4 (30 parts) and Perocta O (0.5 parts) was added dropwise over 1 hour. Thereafter, the temperature was raised to 110° C. and maintained for 1 hour, then 41.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 2 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 9>
50 parts of YUBASE4, 47.6 parts of YUBASE4 solution of macromonomer M1 obtained in Production Example 2, ethyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: EA ), 41 parts of LA, 0.03 parts of Perbutyl O, and 0.2 parts of Nofmer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. After the liquid temperature was raised to 85° C. and held for 3.5 hours, a mixed liquid consisting of YUBASE4 (42 parts) and Perbutyl O (0.015 parts) was added dropwise over 2 hours. Furthermore, after holding at 85° C. for 1 hour, a mixed liquid consisting of YUBASE4 (30 parts) and Perocta O (0.5 parts) was added dropwise over 1 hour. Thereafter, the temperature was raised to 110° C. and maintained for 1 hour, then 41.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 2 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 10>
30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85 ° C., and YUBASE4 (25 parts), nBA (56 parts), ethylhexyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: EHA) (19 parts), Luperox 575 (0.1 parts), NOFUMER A mixture consisting of MSD (0.4 parts) was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 11>
20 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85° C., and a mixed liquid consisting of YUBASE4 (25 parts), nBA (56 parts), LA (19 parts) and Luperox 575 (0.1 parts) was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (60 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 12>
30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of the macromonomer M3 obtained in Production Example 4 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85° C., and a mixed liquid consisting of YUBASE4 (25 parts), nBA (56 parts), LA (19 parts), Luperox 575 (0.1 parts), and Nofmer MSD (0.4 parts) was added. It was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 13>
In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 50 parts of YUBASE4, 47.6 parts of YUBASE4 solution of macromonomer M1 obtained in Production Example 2, 56 parts of nBA, 18 parts of LA, 4- 1 part of hydroxybutyl acrylate (manufactured by Mitsubishi Chemical Co., trade name: 4HBA), 0.03 parts of Perbutyl O and 0.3 parts of Nofmer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. After the liquid temperature was raised to 85° C. and held for 3.5 hours, a mixed liquid consisting of YUBASE4 (42 parts) and Perbutyl O (0.015 parts) was added dropwise over 2 hours. Furthermore, after holding at 85° C. for 1 hour, a mixed liquid consisting of YUBASE4 (30 parts) and Perocta O (0.5 parts) was added dropwise over 1 hour. Thereafter, the temperature was raised to 110° C. and maintained for 1 hour, then 41.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 14>
30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85 ° C., YUBASE 4 (25 parts), nBA (55 parts), LA (17 parts), 4HBA (3 parts), Luperox 575 (0.1 parts), Nofmer MSD (0.9 parts) ) was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 15>
30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85 ° C., YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), hydroxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name: HEA) (1 part), Luperox A mixture of 575 (0.1 parts) and Nofmer MSD (0.5 parts) was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 16>
30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85 ° C., YUBASE 4 (25 parts), LA (65 parts), acrylic acid (manufactured by Mitsubishi Chemical Corporation, trade name: acrylic acid) (10 parts), Luperox 575 (0.1 parts), A mixture consisting of Nofmer MSD (0.8 parts) was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Example 17>
In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 50 parts of YUBASE4, 47.6 parts of the YUBASE4 solution of the macromonomer M4 obtained in Production Example 5, 56 parts of nBA, 19 parts of LA, Perbutyl O and 0.3 part of Nofmer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. After the liquid temperature was raised to 85° C. and held for 3.5 hours, a mixed liquid consisting of YUBASE4 (42 parts) and Perbutyl O (0.015 parts) was added dropwise over 2 hours. Furthermore, after holding at 85° C. for 1 hour, a mixed liquid consisting of YUBASE4 (30 parts) and Perocta O (0.5 parts) was added dropwise over 1 hour. Thereafter, the temperature was raised to 110° C. and maintained for 1 hour, then 41.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Comparative Example 1>
30 parts of YUBASE4 and 85.5 parts of the YUBASE4 solution of the macromonomer M1 obtained in Production Example 2 are added to a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, and dissolved oxygen is removed by bubbling nitrogen while stirring. removed. The liquid temperature was raised to 85° C., and a mixed liquid consisting of YUBASE4 (25 parts), nBA (41 parts), LA (14 parts), Luperox 575 (0.1 parts), and Nofmer MSD (0.2 parts) was added. It was added dropwise over 4 hours. After holding at 85° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After the temperature was raised to 110° C. and maintained for 1 hour, YUBASE4 (40.2 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.

<Comparative Example 2>
In a reaction vessel equipped with a stirrer, condenser and thermometer, 72.6 parts YUBASE4, 13 parts nBA, 62 parts LA, 25 parts Acryester SL, 0.03 parts Perbutyl O, 0 Nofmer MSD 0.08 part was added, and dissolved oxygen was removed by bubbling nitrogen while stirring. After the liquid temperature was raised to 85° C. and held for 3.5 hours, a mixed liquid consisting of YUBASE4 (40 parts) and Perbutyl O (0.015 parts) was added dropwise over 2 hours. Furthermore, after holding at 85° C. for 1 hour, a mixed liquid consisting of YUBASE4 (60 parts) and Perocta O (0.5 parts) was added dropwise over 1 hour. After that, the temperature was raised to 110° C. and maintained for 1 hour, then 11.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35% by mass of a (meth)acrylic copolymer. Table 3 shows the evaluation results of the obtained friction modifier for lubricating oil.
Comparative Example 1 contained more than 40% by mass of structural units derived from the macromonomer (a1), and Comparative Example 2 did not contain structural units derived from (a1), resulting in a high coefficient of friction.

Abbreviations in Tables 1-3 are as follows.
- SLMA: a mixture of an alkyl methacrylate having an alkyl group having 12 carbon atoms and an alkyl methacrylate having an alkyl group having 13 carbon atoms (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester SL)
・SMA: stearyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester S)
・MMA: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester M)
M1: macromonomer synthesized in Production Example 2 M2: macromonomer synthesized in Production Example 3 M3: macromonomer synthesized in Production Example 4 M4: macromonomer synthesized in Production Example 5 nBA: n-butyl Acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: butyl acrylate)
・ EA: Ethyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: ethyl acrylate)
・ LA: Lauryl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name: LA)
・EHA: 2-ethylhexyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: 2-ethylhexyl acrylate)
・ 4HBA: 4-hydroxybutyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: 4HBA)
・ HEA: Hydroxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name: HEA)
・ AA: acrylic acid (manufactured by Mitsubishi Chemical Corporation, trade name: acrylic acid)

Claims (7)

A (meth)acrylic copolymer A containing a structural unit derived from the macromonomer (a1) and a structural unit derived from an alkyl acrylate (a2) having an alkyl group having 1 to 4 carbon atoms, wherein the (meth)acrylic A friction modifier for lubricating oil, wherein the content of the structural unit derived from the macromonomer (a1) is 1 to 40% by mass with respect to 100% by mass of the total mass of the copolymer A. 2. The friction modifier for lubricating oil according to claim 1, wherein the (meth)acrylic copolymer A further contains a structural unit derived from an alkyl acrylate (a3) having 5 to 30 carbon atoms. 2. The friction modifier for lubricating oil according to claim 1, wherein the macromonomer (a1) contains a constitutional unit derived from the vinyl-based radically polymerizable monomer m. 4. The friction modifier for lubricating oil according to claim 3, wherein the vinyl-based radically polymerizable monomer m contains an alkyl methacrylate m _L having an alkyl group with 5 to 30 carbon atoms. The friction modifier for lubricating oil according to claim 1, wherein the macromonomer (a1) has a structure represented by the following formula (1).

(Wherein, X ¹ to X ^n-1 each independently represent a hydrogen atom, a methyl group or CH ₂ OH, Y ¹ to Y ⁿ each independently represent a monomer of the macromonomer (a1) A substituent other than X ¹ to X ^n-1 bonded to the vinyl group of component m, which is a structural unit, Z represents a terminal group, and n represents an integer of 2 to 10,000.) The friction modifier for lubricating oil according to claim 1, wherein the (meth)acrylic copolymer A further contains a structural unit derived from (meth)acrylate (a4) represented by the following general formula (2).

(In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² represents a hydrogen atom or an organic group containing a polar group.) A lubricating oil composition comprising the friction modifier for lubricating oil according to any one of claims 1 to 6.