JP7852666B2 - Anti-wear agents and lubricating oil compositions - Google Patents

Description

This invention relates to anti-wear agents and lubricating oil compositions.

In recent years, to improve fuel efficiency, automotive transmissions have been required to be more efficient in power transmission and to be smaller and lighter. Transmission mechanisms have evolved from manual transmissions to automatic transmissions, and more recently, continuously variable transmissions (CVTs) are being installed in some vehicles. Meanwhile, electric vehicles equipped with lead-acid batteries, nickel-metal hydride batteries, lithium-ion batteries, fuel cells, etc., and fitted with electric motors, or hybrid vehicles that use these batteries in combination with internal combustion engines, have been developed. In these vehicles, transmission fluid and electric motor fluid have traditionally been used separately.

Recently, in electric and hybrid vehicles, there has been a growing demand for the standardization of these oils and for miniaturization and weight reduction through the packaging of the transmission and electric motor. Therefore, there is a need for a new oil that possesses not only the wear-preventive properties of manual, automatic, or continuously variable transmission oils, but also the insulating and copper-compatible properties of electric motor oil.

To meet requirements such as wear prevention and seizure prevention, anti-wear agents are used. Generally, phosphate esters, zinc dithiophosphate, and organic sulfur compounds are added to mineral oil-based or synthetic base oils. However, transmission fluids containing these anti-wear agents corrode copper and have insufficient insulation properties. Therefore, when used as electric motor fluid, they can cause problems such as copper wire damage and short circuits in the electric motor. Consequently, electric vehicles and hybrid vehicles require anti-wear agents that offer a balance of copper compatibility, insulation, and wear prevention.

As anti-wear agents that do not impair copper compatibility and insulation, polymer-type anti-wear agents that do not contain sulfur or phosphorus as constituent elements are known. Specifically, copolymers consisting of α-olefin and fumarate ester (Patent Document 1), acrylic acid ester copolymers having hydroxyl groups (Patent Document 2), polyesters having hydrophilic polymer units and polyolefin units (Patent Document 3), and methacrylic acid ester copolymers having a block structure consisting of polar segment units and hydrophobic segment units (Patent Document 4) are known. However, the above-mentioned polymer anti-wear agents have the problem of not having sufficient anti-wear effect.

Furthermore, (meth)acrylic acid ester copolymers, which have a specific monomer structure as an essential constituent monomer, are known as friction modifiers (Patent Documents 5, 6, and 7). However, while these friction modifiers have a high friction reduction effect, their wear prevention effect remains unclear. Moreover, the (meth)acrylic acid ester copolymer having a constituent monomer containing a carboxyl group, as described in Patent Document 7, raises concerns about copper corrosion involving the carboxyl group, but this aspect has not been studied to date.

Patent No. 3730660 Patent No. 5822706 Patent No. 5684832 Japanese Patent Publication No. 4686444 Japanese Patent Publication No. 2022-151618 Patent No. 6582021 Japanese Patent Publication No. 2020-139146

The object of the present invention is to provide an anti-wear agent with low copper corrosiveness and high anti-wear effect, and a lubricating oil composition containing the same.

The inventors arrived at the present invention after diligent research.
In other words, the present invention relates to an anti-wear agent containing a copolymer (A) having monomer (a) represented by the following general formula (1), monomer (b) represented by the following general formula (2), and monomer (c) represented by the following general formula (3) as essential constituent monomers, wherein the weight ratio (a/b) of monomer (a) to monomer (b) in the copolymer (A) is 0.5 to 80; and a lubricating oil composition containing the anti-wear agent and a base oil.

[In general formula (1), A is a polymerizable unsaturated group having 2 to 5 carbon atoms; ^-X1- , ^-X2- , and ^-X3- are each independently represented by -O- or -NH-; ^R1 is an alkylene group having 1 to 4 carbon atoms; ^R2 is an alkylene group having 2 to 20 carbon atoms; ^R3 is a hydrogen atom, a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, a phenyl group in which the hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, an acyl group having a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, or a benzoyl group in which the hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms; p is an integer from 1 to 100, and when p is 2 or more, the multiple ^R2 and ^X3 may be the same or different.]

[In general formula (2), R ⁴ is a hydrogen atom or a methyl group; -X ^4- is a group represented by -O- or -NH-; R ⁵ represents an alkylene group having 1 to 10 carbon atoms. q is an integer from 1 to 100, and when q is 2 or greater, R ⁵ may be the same or different.]

[In general formula (3), R ⁶ is a hydrogen atom or a methyl group; -X ^5- is a group represented by -O- or -NH-; and R ⁷ is a linear or branched alkyl group having 5 to 44 carbon atoms.]

The anti-wear agent of the present invention and the lubricating oil composition containing the anti-wear agent of the present invention exhibit low copper corrosivity and excellent anti-wear effects.

<Abrasion inhibitor>
The anti-wear agent of the present invention contains a copolymer (A) whose essential constituent monomers are monomer (a) represented by the following general formula (1), monomer (b) represented by the following general formula (2), and monomer (c) represented by the following general formula (3).
In the present invention, the weight ratio (a/b) of monomer (a) to the weight of monomer (b) in the monomer constituting copolymer (A) is 0.5 to 80.

[In general formula (1), A is a polymerizable unsaturated group having 2 to 5 carbon atoms; ^-X1- , ^-X2- , and ^-X3- are each independently represented by -O- or -NH-; ^R1 is an alkylene group having 1 to 4 carbon atoms; ^R2 is an alkylene group having 2 to 20 carbon atoms; ^R3 is a hydrogen atom, a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, a phenyl group in which the hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, an acyl group having a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, or a benzoyl group in which the hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms; p is an integer from 1 to 100, and when p is 2 or more, the multiple ^R2 and ^X3 may be the same or different.]

[In general formula (2), R ⁴ is a hydrogen atom or a methyl group; -X ^4- is a group represented by -O- or -NH-; R ⁵ represents an alkylene group having 1 to 10 carbon atoms. q is an integer from 1 to 100, and when q is 2 or greater, R ⁵ may be the same or different.]

[In general formula (3), R ⁶ is a hydrogen atom or a methyl group; -X ^5- is a group represented by -O- or -NH-; and R ⁷ is a linear or branched alkyl group having 5 to 44 carbon atoms.]

<Copolymer (A)>
In the present invention, copolymer (A) contains monomer (a) represented by general formula (1), monomer (b) represented by general formula (2), and monomer (c) represented by general formula (3) as essential constituent monomers, and the weight ratio (a/b) of monomer (a) to the weight of monomer (b) in the monomers constituting (A) is 0.5 to 80.

In this invention, copolymer (A) contains monomer (a) represented by the general formula (1) as an essential constituent monomer. By containing monomer (a) as a constituent monomer, copolymer (A) can exhibit excellent wear prevention effects.

In general formula (1), A is a polymerizable unsaturated group having 2 to 5 carbon atoms. A polymerizable unsaturated group refers to a functional group having a carbon-carbon double bond that can undergo addition polymerization, and specifically includes radical polymerizable unsaturated groups or cationic polymerizable unsaturated groups. Examples of polymerizable unsaturated groups include alkenyl groups having 2 to 5 carbon atoms {for example, vinyl group, allyl group, homoallyl group (3-butenyl group), 2-butenyl group, methallyl group (2-methyl-1-propenyl group), 3-methyl-3-butenyl group, 3-methyl-2-butenyl group, 2-methyl-3-butenyl group, 2-methyl-2-butenyl group, and 1,1-dimethyl-2-propenyl group}, (meth)acryloyl group, etc.
From the viewpoint of wear resistance, A is preferably a vinyl group and a (meth)acryloyl group, and more preferably a (meth)acryloyl group.
In this invention, "(meth)acryloyl" means "acryloyl and/or methacryloyl," and "(meth)acrylate" means "acrylate and/or methacrylate."

In general formula (1), ^-X1- , ^-X2- , and ^-X3- are each independently represented groups by -O- or -NH-.
^-X1- , ^-X2- , and ^-X3- are preferably -O- from the viewpoint of wear prevention.

In general formula (1), ^R1 is an alkylene group having 1 to 4 carbon atoms.
Examples of alkylene groups having 1 to 4 carbon atoms include methylene groups, ethylene groups, 1,2- or 1,3-propylene groups, and 1,2-, 1,3- or 1,4-butylene groups. Of these, from the viewpoint of wear prevention, ethylene groups and 1,2- or 1,3-propylene groups are preferred, and ethylene groups are even more preferred.

In general formula (1), p represents the total number of moles of lactam and lactone added, as described below, and is an integer from 1 to 100. From the viewpoint of wear prevention and base oil solubility, it is preferably an integer from 1 to 70, more preferably an integer from 1 to 40, particularly preferably an integer from 1 to 20, and most preferably an integer from 1 to 10.
If p is 2 or greater, the multiple ^R2 and ^X3 can be the same or different.
In monomer (a) of the monomer constituting copolymer (A), the average value of p per mole of monomer (a) (average number of moles added, also hereinafter referred to as the molar average value of p) is preferably 1.9 to 70, more preferably 1.9 to 40, particularly preferably 1.9 to 20, and most preferably 1.9 to 10, from the viewpoint of wear prevention and base oil solubility.
If the copolymer (A) consists of two or more monomers (a), the molar mean value of p in general formula (1) is obtained by weighting the p values of each monomer (a) based on the mole fraction of each monomer in monomer (a).
When measuring p in monomer (a), the molar average value of p can be measured from the ^1H -NMR (nuclear magnetic resonance) spectrum of monomer (a). For example, if "lactam and/or lactone" is ε-caprolactone, the molar average value of p can be calculated by dividing half of the integral value of the peak around 1.4 ppm (the peak of the γ hydrogen of the carbonyl carbon derived from ε-caprolactone) by the integral value of the peak around 6.4 ppm or 6.1 ppm (one of the hydrogen atoms bonded to the unsaturated double bond of the acryloyl group or methacryloyl group).
The γ hydrogen of the carbonyl carbon derived from ε-caprolactone refers to the hydrogen atom bonded to the carbon atom marked with an asterisk (*) in the structural formula derived from ε-caprolactone (-CO- _CH2 - _CH2 - _C ^* H2- _CH2 - _CH2 -O-).
A hydrogen atom bonded to the unsaturated double bond of an acryloyl group refers to a hydrogen atom bonded to the carbon atom marked with an asterisk (*) in the structural formula of the acryloyl group, _H₂C ^* =CH-CO-.
A hydrogen atom bonded to the unsaturated double bond of a methacryloyl group refers to a hydrogen atom bonded to the carbon atom marked with an asterisk (*) in the structural formula of the methacryloyl group, _H₂C ^* = C( _CH₃ )-CO-.
Specifically, the molar mean of p can be calculated using the following formula.
(When ^A1 in general formula (1) is an acryloyl group)
The molar mean of p = (integral value of the peak of the γ hydrogen of the carbonyl carbon derived from ε-caprolactone / 2) / (integral value of one of the peaks of hydrogen atoms bonded to the unsaturated double bond of the acryloyl group)
(When ^A1 in general formula (1) is a methacryloyl group)
The molar mean of p = (integral value of the peak of the γ hydrogen of the carbonyl carbon derived from ε-caprolactone / 2) / (integral value of one of the peaks of hydrogen atoms bonded to the unsaturated double bond of the methacryloyl group)

In general formula (1), R ² represents an alkylene group having 2 to 20 carbon atoms. Specifically, alkylene groups having 2 to 20 carbon atoms include: ethylene group, isopropylene group, 1,2- or 1,3-propylene group, isobutylene group, 1,2-, 1,3- or 1,4-butylene group, isopentylene group, 1,2-, 1,3-, 1,4- or 1,5-pentylene group, isohexylene group, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexylene group, isoheptylene group, 1,2-, 1,3-, 1,4-, 1,5-, 1,6- or 1,7-heptylene group, isooctylene, 1,8-octylene group, isononylene group, 1,9-nonylene group, and Examples include sodecylene group, 1,10-decylene group, isoundecylene group, 1,11-undecylene group, isododecylene group, 1,12-dodecylene group, isotridecylene group, 1,13-tridecylene group, isotetradecylene group, 1,14-tetradecylene group, isopentadecylene group, 1,15-pentadecylene group, isohexadecylene group, 1,16-hexadecylene group, isoheptadecylene group, 1,17-heptadecylene group, isooctadecylene group, 1,18-isooctadecylene group, isononadecylene group, 1,19-isonononadecylene group, isoeicosilene group, 1,20-eicosilene group, and the like.
From the viewpoint of wear prevention, ^R2 is preferably an alkylene group having 2 to 17 carbon atoms, more preferably an alkylene group having 2 to 15 carbon atoms, particularly preferably an alkylene group having 2 to 13 carbon atoms, and most preferably an alkylene group having 2 to 10 carbon atoms.

In general formula (1), ^R3 is a hydrogen atom, a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, a phenyl group in which the hydrogen atoms in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, an acyl group having a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, or a benzoyl group in which the hydrogen atoms in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms.

Specifically, linear or branched aliphatic hydrocarbon groups having 1 to 44 carbon atoms include saturated aliphatic strained hydrogen groups (alkyl groups) {for example, methyl group, ethyl group, propyl group, butyl group, hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, n-decyl group, isodecyl group, n-undecyl group, isoundecyl group, n-dodecyl group, isododecyl group, n-tridecyl group}. n-tetradecyl group, isotridecyl group, n-tetradecyl group, 2-ethyldodecyl group, n-pentadecyl group, 2-methyltetradecyl group, n-hexadecyl group, isohexadecyl group, n-heptadecyl group, isoheptadecyl group, 2-ethylpentadecyl group, 2-octylnonyl group, 2-(3-methylhexyl)-7-methylnonyl group, n-octadecyl group, isooctadecyl group, 2-hexylundecyl 1-ethylheptadecyl group, 2-ethylheptadecyl group, 1-hexyltridecyl group, n-icosyl group, 2-octylundecyl group, isoicosyl group, 1-undecyldodecyl group, 1-octylpentadecyl group, 2-decyltridecyl group, n-tetraicosyl group, 2-decyltetradecyl group, 2-dodecylpentadecyl group, 2-heptylicosyl group, 2-dodecylhexadecyl group, n-triacontyl group, 2-tetraicosyl group Examples include residues obtained by removing hydroxyl groups from oxo alcohols derived from tetracontyl groups (such as trandecyloctadecyl groups, n-hexatriacontyl groups, n-tetracontyl groups, and 2-ethyltetracontyl groups), unsaturated linear aliphatic hydrocarbon groups, and olefins [e.g., propylene oligomers (2-14 units), ethylene/propylene oligomers (2-20 units), and isobutene oligomers (2-10 units)].

Examples of phenyl groups in which the hydrogen atoms in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms include the phenyl group, the o-, m-, or p-methylphenyl group, and the o-, m-, or p-ethylphenyl group.
Examples of acyl groups having a linear or branched aliphatic hydrocarbon group with 1 to 44 carbon atoms include acetyl, propionyl, butyryl, isobutyryl, valeryl, isovaleryl, and piperoyl groups.
Examples of benzoyl groups in which the hydrogen atoms in the aromatic ring may be substituted with linear or branched aliphatic hydrocarbon groups having 1 to 44 carbon atoms include benzoyl groups and toluyl groups.

Of these ^R3s , from the viewpoint of wear prevention, preferred are a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an acyl group having 1 to 12 carbon atoms, a phenyl group which may be substituted with a linear or branched alkyl group having 1 to 12 carbon atoms, or a benzoyl group which may be substituted with a linear or branched alkyl group having 1 to 12 carbon atoms, and more preferably a hydrogen atom.

From the viewpoint of wear prevention, preferred monomers (a) include 1 to 100 mole lactone adducts of hydroxyalkyl (meth)acryloyl monomers (a1), 1 to 100 mole lactam adducts of hydroxyalkyl (meth)acryloyl monomers (a2), 1 to 100 mole lactone adducts of aminoalkyl (meth)acryloyl monomers (a3), and 1 to 100 mole lactam adducts of aminoalkyl (meth)acryloyl monomers (a4), as well as esterified products (a5) or amidated products (a6) of (a1) to (a4) with monocarboxylic acids (e.g., monocarboxylic acids having 2 to 45 carbon atoms), and etherified products (a7) resulting from the reaction of (a1) or (a3) with alkylating agents or aromatic halides having 1 to 44 carbon atoms. More preferably, 1 to 100 mole lactone adducts (a1) of hydroxyalkyl (meth)acryloyl monomers are used.

Examples of hydroxyalkyl (meth)acryloyl monomers include hydroxyalkyl (meth)acrylates {hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, etc.} and hydroxyalkyl (meth)acrylamides {hydroxymethyl (meth)acrylamide, hydroxyethyl (meth)acrylamide, hydroxypropyl (meth)acrylamide, hydroxybutyl (meth)acrylamide, etc.}.

Examples of aminoalkyl (meth)acryloyl monomers include aminoalkyl (meth)acrylates {aminomethyl (meth)acrylate, aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, aminobutyl (meth)acrylate, etc.} and aminoalkyl (meth)acrylamides {aminomethyl (meth)acrylamide, aminoethyl (meth)acrylamide, aminopropyl (meth)acrylamide, aminobutyl (meth)acrylamide, etc.}.

Lactones include those with 3 to 21 carbon atoms, such as β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone.

Lactams include those with 3 to 21 carbon atoms, such as β-lactams, γ-lactams, and δ-lactams.

Examples of monocarboxylic acids include monocarboxylic acids having 2 to 45 carbon atoms {e.g., linear saturated aliphatic monocarboxylic acids (e.g., ethaneic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, etc.), linear unsaturated aliphatic monocarboxylic acids (e.g., oleic acid, linoleic acid, linolenic acid, arachidonic acid, docosahexanoic acid, etc.)}, and aromatic monocarboxylic acids (e.g., benzoic acid, and those in which some of the hydrogen atoms bonded to the aromatic ring of benzoic acid are substituted with linear aliphatic hydrocarbon groups having 1 to 44 carbon atoms (e.g., 4-alkyl (alkyl group with 1 to 44 carbon atoms) benzoic acid, etc.)).

Examples of alkylating agents having 1 to 44 carbon atoms include alkyl chlorides such as methyl chloride, ethyl chloride, propyl chloride, butyl chloride, isopropyl chloride, and allyl chloride; and alkyl bromides such as methyl bromide, ethyl bromide, propyl bromide, butyl bromide, and isopropyl bromide.
Aromatic halides include halogenated aromatic compounds such as fluorinated and chlorinated compounds, and examples include halogenated benzenes and halogenated alkylbenzenes having a chain-like aliphatic hydrocarbon group with 1 to 44 carbon atoms (e.g., 1-halogenated-4-alkyl(alkyl group with 1 to 44 carbon atoms)benzene).

As monomer (a), from the viewpoint of wear prevention, preferably a 1-20 molar adduct of hydroxyalkyl (hydroxyalkyl group with 1-4 carbon atoms) (meth)acrylate lactone, an alkylated compound of a 1-20 molar adduct of hydroxyalkyl (hydroxyalkyl group with 1-4 carbon atoms) (meth)acrylate lactone having 1-12 carbon atoms, an aromatic halogenated compound (may have an alkyl group with 1-12 carbon atoms) of a 1-20 molar adduct of hydroxyalkyl (hydroxyalkyl group with 1-4 carbon atoms) (meth)acrylate lactone, or a carbon atom Esterilizations with 2 to 13 chain-like aliphatic monocarboxylic acids, esterifications of 1 to 20 moles of lactone adducts of hydroxyalkyl (hydroxyalkyl group with 1 to 4 carbon atoms) (meth)acrylate with aromatic monocarboxylic acids (which may have an alkyl group with 1 to 12 carbon atoms), and more preferably, 1 to 20 moles of ε-caprolactone adducts of hydroxyalkyl (hydroxyalkyl group with 2 to 3 carbon atoms) (meth)acrylate, alkylated products of 1 to 12 carbon atoms of ε-caprolactone adducts of hydroxyalkyl (hydroxyalkyl group with 2 to 3 carbon atoms) (meth)acrylate, and hydroxyalkyl (hydroxyalkyl group with 1 to 12 carbon atoms) 2-3) Aromatic halogenated products (may have an alkyl group having 1 to 12 carbon atoms) of 1 to 20 moles of ε-caprolactone adduct of (meth)acrylate, esterified products of 1 to 20 moles of ε-caprolactone adduct of hydroxyalkyl (hydroxyalkyl group having 2 to 3 carbon atoms) (meth)acrylate with a chain aliphatic monocarboxylic acid having 2 to 13 carbon atoms, and esterified products of 1 to 20 moles of ε-caprolactone adduct of hydroxyalkyl (hydroxyalkyl group having 2 to 3 carbon atoms) (meth)acrylate with an aromatic monocarboxylic acid (may have an alkyl group having 1 to 12 carbon atoms), and particularly preferably ε-caprolactone adduct of hydroxyethyl (meth)acrylate. These include lactone adducts of 1 to 20 moles, alkylates of hydroxyethyl (meth)acrylate adducts of ε-caprolactone of 1 to 20 moles with 1 to 12 carbon atoms, aromatic halogenated compounds (which may have alkyl groups with 1 to 12 carbon atoms) of hydroxyethyl (meth)acrylate adducts of ε-caprolactone of 1 to 20 moles, esterified compounds of hydroxyethyl (meth)acrylate adducts of ε-caprolactone of 1 to 20 moles with chain-like aliphatic monocarboxylic acids with 2 to 13 carbon atoms, and esterified compounds of hydroxyethyl (meth)acrylate adducts of ε-caprolactone of 1 to 20 moles with aromatic monocarboxylic acids (which may have alkyl groups with 1 to 12 carbon atoms).

Lactone adducts of hydroxyalkyl (meth)acryloyl monomers or aminoalkyl (meth)acryloyl monomers in amounts of 1 to 100 moles can be obtained, for example, by ring-opening addition of a lactone to a hydroxyalkyl (meth)acryloyl monomer or aminoalkyl (meth)acryloyl monomer.
The reaction temperature for the ring-opening addition reaction is preferably 80 to 150°C, and more preferably 100 to 140°C, from the viewpoint of reaction time.
The reaction time is preferably 2 to 24 hours, and more preferably 3 to 10 hours.
The reaction may be carried out in the presence of a catalyst.
Any known catalyst can be used as the catalyst for the above reaction, including p-toluenesulfonic acid, tetrapropyl titanate, and stannous octanoate.
The amount of catalyst used is preferably 0.01 to 5% by mass, and more preferably 0.03 to 0.5% by mass, relative to the amount of reaction product.
After the ring-opening addition reaction is complete, it is desirable to treat the catalyst by methods such as adsorption and filtration using an adsorbent, or neutralization to deactivate the catalyst.

Lactam adducts of hydroxyalkyl (meth)acryloyl monomers or aminoalkyl (meth)acryloyl monomers in quantities of 1 to 100 moles can be obtained, for example, by ring-opening addition of a lactam to a hydroxyalkyl (meth)acryloyl monomer or aminoalkyl (meth)acryloyl monomer.
The reaction temperature for the ring-opening addition reaction of lactam is preferably 80 to 150°C, and more preferably 100 to 140°C, from the viewpoint of reaction time.
The reaction time is preferably 2 to 24 hours, and more preferably 3 to 10 hours.
The reaction may be carried out in the presence of a catalyst.
Any known catalyst can be used as the catalyst for the above reaction, such as tetrapropyl titanate or stannous octanoate.
The amount of catalyst used is preferably 0.01 to 5% by weight, and more preferably 0.03 to 0.5% by weight, relative to the amount of reaction product.
After the ring-opening addition reaction is complete, it is desirable to treat the catalyst by methods such as adsorption and filtration using an adsorbent, or neutralization to deactivate the catalyst.

The reaction temperature when esterifying (a1) to (a4) with a monocarboxylic acid is preferably 80°C to 150°C, and more preferably 90°C to 130°C, from the viewpoint of reaction time and prevention of polymerization of (meth)acrylic acid.
The esterification reaction may be carried out under reduced pressure to remove the water produced. The preferred reaction pressure is preferably 0.007 to 0.095 MPa, and more preferably 0.01 to 0.092 MPa, from the viewpoint of reaction time and polymerization prevention.
The reaction time is preferably 2 to 24 hours, and more preferably 3 to 10 hours. The esterification reaction is preferably carried out in the presence of a catalyst.
Any known catalyst can be used as the catalyst for the esterification reaction described above, such as sulfuric acid or p-toluenesulfonic acid. A solvent may also be used in the esterification reaction, and suitable solvents include non-aqueous solvents with a boiling point of 150°C or lower, such as cyclohexane and toluene.

The reaction temperature when amidating (a1) to (a4) with a monocarboxylic acid is preferably 80°C to 150°C, and more preferably 90°C to 130°C, from the viewpoint of reaction time and prevention of polymerization of (meth)acrylic acid.
Furthermore, the amidation reaction may be carried out under reduced pressure to remove the water produced. The preferred reaction pressure is preferably 0.007 to 0.095 MPa, and more preferably 0.01 to 0.092 MPa, from the viewpoint of reaction time and polymerization prevention.
The reaction time is preferably 2 to 24 hours, and more preferably 3 to 10 hours.

The reaction between (a1) or (a3) and an alkylating agent having 1 to 44 carbon atoms can be obtained by reacting under general conditions in the presence of an alkali (e.g., an amine, a quaternary ammonium salt, sodium hydroxide, etc.).

From the viewpoint of solubility in lubricating oil base oil, the constituent units derived from monomer (a) (structures in which the polymerizable vinyl groups of (a) react to form single bonds) are preferably those that have a specific solubility parameter (sometimes abbreviated as SP value below).
The SP value of the constituent units derived from monomer (a) is preferably 9.0 to 12.5 (cal/ ^cm³ ) ^1/2 , more preferably 9.3 to 12.3 (cal/ ^cm³ ) ^1/2 , and particularly preferably 9.5 to 12.0 (cal/ ^cm³ ) ^1/2 .
In this invention, the SP value refers to the value calculated using the formula (28) on page 153 of the Fedors method (Polymer Engineering and Science, February, 1974, Vol. 14, No. 2, pp. 147-154), using the numerical values (heat of vaporization and molar volume of an atom or functional group at 25°C) described on page 152 (Table 5). Specifically, it can be calculated by applying the numerical values corresponding to the types of atoms and atomic groups in the molecular structure from the Δe _i and vi _i values listed in Table 1 below, which are parameters of the Fedors method, to the following formula.
SP value = (ΣΔe _i /Σv _i ) ^1/2

Furthermore, when copolymer (A) uses two or more monomers (a) as monomers, it is preferable that the SP value of monomer (a) is calculated by determining the SP value of each of the multiple monomers constituting (A) using the method described above, and then taking the arithmetic mean of the SP values of each monomer (a) based on their weight fractions, so that the result is within the aforementioned range.

The molecular formula weight or number average molecular weight (hereinafter abbreviated as Mn) of monomer (a) is preferably 150 to 20,000, more preferably 150 to 10,000, particularly preferably 150 to 7,000, and most preferably 150 to 4,000, from the viewpoint of wear prevention.
Furthermore, the molecular weight or Mn of (a) and the weight-average molecular weight (hereinafter abbreviated as Mw) of copolymer (A) described later can be measured by gel permeation chromatography (hereinafter abbreviated as GPC) under the following conditions.
<Measurement conditions for Mn in (a) and Mw in (A)>
Equipment: "HLC-8320GPC" [Manufactured by Tosoh Corporation]
Columns: 1 x "TSKgel guardcolumn SuperHZ-L" [manufactured by Tosoh Corporation], 3 x "TSKgel Super HZM-M" [manufactured by Tosoh Corporation]. Measurement temperature: 40°C
Sample solution: 0.25% by weight tetrahydrofuran solution; Solution injection volume: 10 μl
Detection device: RI (Differential Refractometer)
Reference material: Standard polystyrene (TSK standard POLYSTYRENE) 11 samples (molecular weight: 589, 1,013, 2,630, 9,100, 19,500, 37,900, 96,400, 190,000, 427,000, 1,090,000, 2,110,000) [Manufactured by Tosoh Corporation]

In this invention, copolymer (A) contains monomer (b) represented by the general formula (2) as an essential constituent monomer. In this invention, it is presumed that by having monomer (b) as a constituent monomer of copolymer (A), the carboxyl groups of monomer (b) enhance the adsorption force to the metal, thereby improving the wear prevention effect.

In general formula (2), ^R4 is either a hydrogen atom or a methyl group, and of these, both a hydrogen atom and a methyl group are preferred from the viewpoint of preventing wear.

In general formula (2), ^-X4- is a group represented by -O- or -NH-, and of these, the group represented by -O- is preferred from the viewpoint of preventing wear.

In general formula (2), R ⁵ is an alkylene group having 1 to 10 carbon atoms.
Examples of alkylene groups having 1 to 10 carbon atoms include methylene, ethylene, isopropylene, 1,2- or 1,3-propylene, isobutylene, 1,2-, 1,3- or 1,4-butylene, isopentylene, 1,2-, 1,3-, 1,4- or 1,5-pentylene, isohexylene, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexylene, isoheptylene, 1,2-, 1,3-, 1,4-, 1,5-, 1,6- or 1,7-heptylene, isooctylene, 1,8-octylene, isononylene, 1,9-nonylene, isodecylene, and 1,10-decylene. Of these, alkylene groups having 1 to 8 carbon atoms are preferred from the viewpoint of preventing wear, alkylene groups having 2 to 6 carbon atoms are more preferred, and alkylene groups having 2 to 5 carbon atoms are particularly preferred.

In general formula (2), q is an integer from 1 to 100, preferably an integer from 1 to 50, more preferably an integer from 1 to 20, and particularly preferably an integer from 1 to 10, from the viewpoint of preventing wear. When q is 2 or more, the multiple ^R5s may be the same or different.

Specific examples of monomer (b) include carboxyalkyl (1-10 carbon atoms) (meth)acrylate, carboxypolyacetolactone mono(meth)acrylate (with 2-100 moles of α-acetolactone added), carboxypolypropiolactone mono(meth)acrylate (with 2-100 moles of β-propiolactone added), carboxypolybutyrolactone mono(meth)acrylate (with 2-100 moles of γ-butyrolactone added), carboxypolyvalerolactone mono(meth)acrylate (with 2-100 moles of δ-valerolactone added), and carboxypolycaprolactone mono(meth)acrylate (with 2-100 moles of ε-caprolactone added).

Monomer (b) can be obtained, for example, by the reaction of a lactone having 2 to 11 carbon atoms (e.g., α-acetolactone, β-propiolactone, γ-butyrolactone, β-butyrolactone, δ-valerolactone, γ-valerolactone, ε-caprolactone, δ-caprolactone, and γ-caprolactone, etc.) with (meth)acrylic acid or (meth)acrylamide.
Furthermore, monomers (b) such as β-carboxyethyl acrylate (product name "β-CEA", manufactured by Daicel Ornex Co., Ltd.) and ω-carboxy-polycaprolactone (2-mol adduct) monoacrylate (product name "Aronics M-5300", manufactured by Toagosei Co., Ltd.) are commercially available and can be obtained.

In the present invention, copolymer (A) contains monomer (c) represented by the general formula (3) as an essential constituent monomer. The inclusion of monomer (c) as a constituent monomer tends to improve solubility in the base oil.

In general formula (3), R ⁶ is either a hydrogen atom or a methyl group, and of these, a methyl group is preferred from the viewpoint of wear prevention and viscosity index improvement effect.

In general formula (3), ^-X5- is a group represented by -O- or NH-, and of these, -O- is preferred from the viewpoint of wear prevention.

In general formula (3), ^R7 is a linear or branched alkyl group having 5 to 44 carbon atoms, for example, pentyl group, hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, n-decyl group, isodecyl group, n-undecyl group, isoundecyl group, n-dodecyl group, isododecyl group, n-tridecyl group, isotridecyl group, n-tetradecyl group, 2-ethyldodecyl group, n-pentadecyl group, 2-methyltetradecyl group, n-hexadecyl group, isohexadecyl group, n-heptadecyl group, isoheptadecyl group, 2-ethylpentadecyl group, 2-octylnonyl group, 2-(3-methylhexyl)-7-methylnonyl group, n-octadecyl group, isooctadecyl group, 2-hexylundecyl group, Examples include 2-ethylheptadecyl group, 1-hexyltridecyl group, n-icosyl group, 2-octylundecyl group, isoicosyl group, 1-undecyldodecyl group, 1-octylpentadecyl group, 2-decyltridecyl group, n-tetraicosyl group, 2-decyltetradecyl group, 2-dodecylpentadecyl group, 2-heptylicosyl group, 2-dodecylhexadecyl group, n-triacontyl group, 2-tetradecyloctadecyl group, n-hexatriacontyl group, n-tetracontyl group, 2-ethyltetracontyl group, and olefins [e.g., propylene oligomers (2 to 14 units), ethylene/propylene oligomers (2 to 20 units), and isobutene oligomers (2 to 10 units), etc.].

Of the ^R7 components, from the viewpoint of base oil solubility, a linear or branched alkyl group having 10 to 34 carbon atoms is preferred, a linear or branched alkyl group having 12 to 32 carbon atoms is more preferred, a linear or branched alkyl group having 16 to 32 carbon atoms is particularly preferred, and most preferably a linear alkyl group having 16 to 22 carbon atoms and a branched alkyl group having 18 to 32 carbon atoms is preferred.

Examples of monomers (c) include pentyl (meth)acrylate, hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-undecyl (meth)acrylate, isoundecyl (meth)acrylate, n-dodecyl (meth)acrylate, isododecyl (meth)acrylate, n-tridecyl (meth)acrylate, Isotridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, 2-ethyldodecyl (meth)acrylate, n-pentadecyl (meth)acrylate, 2-methyltetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, isohexadecyl (meth)acrylate, n-heptadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, 2-ethylpentadecyl (meth)acrylate, 2-octyrnonyl (meth)acrylate, 2-(3-methylhexyl)-7-methyl Lu-nonyl (meth)acrylate, n-octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, 2-hexylundecyl (meth)acrylate, 2-ethylheptadecyl (meth)acrylate, 1-hexyltridecyl (meth)acrylate, n-icosyl (meth)acrylate, 2-octylundecyl (meth)acrylate, isoicosyl (meth)acrylate, 1-undecyldodecyl (meth)acrylate, 1-octylpentadecyl (meth)acrylate, 2-decyltridecyl (meth)acrylate Examples include acrylate, n-tetraicosyl (meth)acrylate, 2-decyltetradecyl (meth)acrylate, 2-dodecylpentadecyl (meth)acrylate, 2-heptylicosyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, n-triacontyl (meth)acrylate, 2-tetradecyloctadecyl (meth)acrylate, n-hexatriacontyl (meth)acrylate, n-tetracontyl (meth)acrylate, and 2-ethyltetracontyl (meth)acrylate.
Of these, from the viewpoint of wear prevention, 2-decyltetradecyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, and 2-tetradecyloctadecyl (meth)acrylate are preferred, and more preferably 2-dodecylhexadecyl (meth)acrylate and 2-tetradecyloctadecyl (meth)acrylate.

Copolymer (A) may contain monomers other than those mentioned above as constituent monomers. For example, it may be a copolymer in which one or more monomers are selected from the group consisting of nitrogen atom-containing monomers (d) other than monomers (a) to (c), hydroxyl group-containing monomers (e) other than monomer (a), and phosphorus atom-containing monomers (f). Furthermore, polymer (A) may contain the following monomers (g) to (n), and a carboxyl-containing monomer (t) other than monomer (b) as constituent monomers.

Examples of nitrogen atom-containing monomers (d) include the following monomers (d1) to (d4).
Amide group-containing monomer (d1):
(meth)acrylamide, monoalkylaminoalkyl(meth)acrylamide [having an aminoalkyl group (2-6 carbon atoms) with one C1-C4 alkyl group bonded to the nitrogen atom; for example, N-methylaminoethyl(meth)acrylamide, N-ethylaminoethyl(meth)acrylamide, N-isopropylamino-n-butyl(meth)acrylamide and N-n- or isobutylamino-n-butyl(meth)acrylamide, etc.], dialkylamino(meth)acrylamide [having two C1-C4 alkyl groups bonded to the nitrogen atom; for example, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide and N, Examples include those having a nitrogen atom only in the amide group, such as N-di-n-butyl(meth)acrylamide, dialkylaminoalkyl(meth)acrylamide [those having an aminoalkyl group (2-6 carbon atoms) in which two alkyl groups with 1-4 carbon atoms are bonded to a nitrogen atom; for example, N,N-dimethylaminoethyl(meth)acrylamide, N,N-diethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and N,N-di-n-butylaminobutyl(meth)acrylamide, etc.], and N-vinyl carboxylic acid amide [N-vinylformamide, N-vinylacetamide, N-vinyl-n- or isopropionylamide, and N-vinylhydroxyacetamide, etc.].

Nitro group-containing monomer (d2):
Examples include 4-nitrostyrene.

Monomers containing primary to tertiary amino groups (d3):
Primary amino group-containing vinyl monomers {alkenylamines with 3 to 6 carbon atoms [(meth)allylamine and clotylamine, etc.], aminoalkyl (2 to 6 carbon atoms) (meth)acrylates [aminoethyl (meth)acrylate, etc.]}; secondary amino group-containing vinyl monomers {monoalkylaminoalkyl (meth)acrylates [those having an aminoalkyl group (2 to 6 carbon atoms) in which one alkyl group of 1 to 6 carbon atoms is bonded to a nitrogen atom; for example, t-butylaminoethyl (meth)acrylate and methylaminoethyl (meth)acrylate, etc.], dialkenylamines with 6 to 12 carbon atoms [di(meth)allylamine, etc.]}; tertiary amino group-containing vinyl monomers {dialkylaminoalkyl (meth)acrylates [nitrogen atom Examples include aminoalkyl groups (having 2 to 6 carbon atoms) to which two alkyl groups having 1 to 6 carbon atoms are bonded; for example, dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate, etc., alicyclic (meth)acrylates having a nitrogen atom [morpholinoethyl (meth)acrylate, etc.], aromatic vinyl monomers [N,N-diphenylaminoethyl (meth)acrylamide, N,N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone and N-vinylthiopyrrolidone, etc.], and their hydrochloride salts, sulfates, phosphates, or lower alkyl (1 to 8 carbon atoms) monocarboxylic acid (acetic acid and propionic acid, etc.) salts.

Nitrile group-containing monomer (d4):
Examples include (meth)acrylonitrile.

Of the nitrogen atom-containing vinyl monomers (d), (d1) and (d3) are preferred, and more preferably are N,N-diphenylaminoethyl (meth)acrylamide, dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate.

Examples of hydroxyl group-containing monomers (e) include the following:
Hydroxyl group-containing aromatic monomers (e.g., p-hydroxystyrene), hydroxyalkyl (C2-C6) (meth)acrylates [e.g., 2-hydroxyethyl (meth)acrylate and 2- or 3-hydroxypropyl (meth)acrylate], mono- or dihydroxyalkyl (C1-C4) substituted (meth)acrylamides [e.g., N,N-dihydroxymethyl (meth)acrylamide, N,N-dihydroxypropyl (meth)acrylamide, N,N-di-2-hydroxybutyl (meth)acrylamide], vinyl alcohol, C3-C12 alkenols [e.g., (meth)aryl alcohol, clotyl alcohol, isocyl alcohol] Examples include rotyl alcohol, 1-octenol and 1-undecenol, etc., alkene monools or alkene diols having 4 to 12 carbon atoms [1-buten-3-ol, 2-buten-1-ol and 2-buten-1,4-diol, etc.], hydroxyalkyl (1 to 6 carbon atoms) alkenyl (3 to 10 carbon atoms) ethers (2-hydroxyethylpropenyl ether, etc.), alkenyl (3 to 10 carbon atoms) ethers or (meth)acrylates of polyhydric (3 to 8 hydric) alcohols (glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, sugars and sucrose, etc.) [sucrose (meth)allyl ether, etc.].

Examples of phosphorus atom-containing monomers (f) include the following monomers (f1) to (f2).

Phosphate ester group-containing monomer (f1):
Examples include (meth)acryloyloxyalkyl (C2-C4) phosphate esters [(meth)acryloyloxyethyl phosphate and (meth)acryloyloxyisopropyl phosphate] and alkenyl phosphate esters [vinyl phosphate, allyl phosphate, propenyl phosphate, isopropenyl phosphate, butenyl phosphate, pentenyl phosphate, octenyl phosphate, decenyl phosphate and dodecenyl phosphate, etc.].

Phosphono group-containing monomer (f2):
Examples include (meth)acryloyloxyalkyl (2-4 carbon atoms) phosphonic acids [such as (meth)acryloyloxyethylphosphonic acid] and alkenyl (2-12 carbon atoms) phosphonic acids [such as vinylphosphonic acid, allylphosphonic acid, and octenylphosphonic acid].

Among the phosphorus atom-containing monomers (f), (f1) is preferred, (meth)acryloyloxyalkyl (C2-C4) phosphate esters are more preferred, and (meth)acryloyloxyethyl phosphate is particularly preferred.

Alkoxyalkyl ether monomer (g);
Methoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, methoxyheptyl (meth)acrylate, methoxyhexyl (meth)acrylate, methoxypentyl (meth)acrylate, methoxyoctyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate, ethoxybutyl (meth)acrylate, ethixyheptyl (meth)acrylate, ethoxyhexyl (meth)acrylate, ethoxypentyl (meth)acrylate, ethoxyoctyl (meth)acrylate, propoxymethyl (meth)acrylate, propoxyethyl Examples include methyl (meth)acrylate, propoxypropyl (meth)acrylate, propoxybutyl (meth)acrylate, propoxyheptyl (meth)acrylate, propoxyhexyl (meth)acrylate, propoxypentyl (meth)acrylate, propoxyoctyl (meth)acrylate, butoxymethyl (meth)acrylate, butoxyethyl (meth)acrylate, butoxypropyl (meth)acrylate, butoxybutyl (meth)acrylate, butoxyheptyl (meth)acrylate, butoxyhexyl (meth)acrylate, butoxypentyl (meth)acrylate, butoxyoctyl (meth)acrylate, etc.
Of the monomers (g), preferred are methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and butoxyethyl (meth)acrylate.

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

Alicyclic hydrocarbon monomers (i):
Examples include cyclohexene, (di)cyclopentadiene, pinene, limonene, vinylcyclohexene, and ethylidene bicycloheptene.

Aromatic hydrocarbon monomers (j):
Examples include styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, indene, 4-clotylbenzene, and 2-vinylnaphthalene.

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

Epoxy group-containing monomer (l):
Examples include glycidyl (meth)acrylate and glycidyl (meth)allyl ether.

Halogen element-containing monomer (m):
Examples include vinyl chloride, vinyl bromide, vinylidene chloride, (meth)allyl chloride, and halogenated styrenes (such as dichlorostyrene).

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

Examples of carboxyl group-containing monomers (t) include (meth)acrylic acid, monomer (t1) represented by the following general formula (4), monomer (t2) represented by the following general formula (5), and monomer (t3) represented by the following general formula (6).

[In general formula (4), ^R8 represents a hydrogen atom or a methyl group; ^-X6- represents a group represented by -O- or -NH-; ^R9 represents an alkylene group having 1 to 10 carbon atoms; ^R10O represents an alkylene oxy group having 2 to 4 carbon atoms; and ^R11 represents an alkylene group having 1 to 12 carbon atoms. u is an integer from 0 to 10, and when u is 2 or greater, ^R10O may be the same or different.]

[In general formula (5), R ¹² is a hydrogen atom or a methyl group; -X ^7- is a group represented by -O- or -NH-; R ¹³ is an alkylene group having 1 to 10 carbon atoms; R ¹⁴ O is an alkylene oxy group having 2 to 4 carbon atoms; and R ¹⁵ is independently a hydrogen atom or a carboxyl group, with at least one representing a carboxyl group. v is an integer from 0 to 10, and when v is 2 or greater, R ¹⁴ O may be the same or different.]

[In general formula (6), R ¹⁶ is a hydrogen atom or a methyl group; -X ⁸ - is a group represented by -O- or -NH-; R ¹⁷ is an alkylene group having 1 to 10 carbon atoms; R ¹⁸ O is an alkylene oxy group having 2 to 4 carbon atoms; and R ¹⁹ is independently a hydrogen atom or a carboxyl group, with at least one representing a carboxyl group. r is an integer from 0 to 10, and when r is 2 or greater, R ¹⁸ O may be the same or different.]

The monomer (t1) is a monomer having one carboxyl group, represented by the general formula (4) above.
In general formula (4), R ⁸ is either a hydrogen atom or a methyl group, and of these, both a hydrogen atom and a methyl group are preferred from the viewpoint of wear prevention.

In general formula (4), ^-X6- is a group represented by -O- or NH-, of which -O- is preferred from the viewpoint of wear prevention.

In general formula (4), ^R9 is an alkylene group having 1 to 10 carbon atoms.
Examples of alkylene groups having 1 to 10 carbon atoms include methylene, ethylene, isopropylene, 1,2- or 1,3-propylene, isobutylene, 1,2-, 1,3- or 1,4-butylene, isopentylene, 1,2-, 1,3-, 1,4- or 1,5-pentylene, isohexylene, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexylene, isoheptylene, 1,2-, 1,3-, 1,4-, 1,5-, 1,6- or 1,7-heptylene, isooctylene, 1,8-octylene, isononylene, 1,9-nonylene, isodecylene, and 1,10-decylene. Of these, ethylene groups, 1,2-propylene groups, and 1,3-propylene groups are preferred from the viewpoint of wear prevention, and ethylene groups are even more preferred.

In general formula (4), R ¹⁰ O is an alkylene oxy group having 2 to 4 carbon atoms. Examples of alkylene oxy groups having 2 to 4 carbon atoms include ethylene oxy group, propylene oxy group, and butylene oxy group. Examples of propylene groups in the propylene oxy group include 1,2-propylene group and 1,3-propylene group, and examples of butylene groups in the butylene oxy group include 1,2-butylene group, 1,3-butylene group, and 1,4-butylene group. From the viewpoint of wear prevention, the alkylene oxy group is preferably an ethylene oxy group and a propylene oxy group, and more preferably an ethylene oxy group.

In general formula (4), u is an integer from 0 to 10, preferably an integer from 0 to 7, more preferably an integer from 0 to 5, and particularly preferably an integer from 0 to 3, from the viewpoint of wear prevention.
If u is 2 or more, the multiple ^R10O atoms may be the same or different.

In general formula (4), R ¹¹ is a residue obtained by removing two carboxyl groups from a dicarboxylic acid having 3 to 14 carbon atoms, and is an alkylene group having 1 to 12 carbon atoms.
Examples of alkylene groups having 1 to 12 carbon atoms include methylene group, ethylene group, isopropylene group, 1,2- or 1,3-propylene group, isobutylene group, 1,2-, 1,3- or 1,4-butylene group, isopentylene group, 1,2-, 1,3-, 1,4- or 1,5-pentylene group, isohexylene group, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexylene group, isoheptylene group, 1,2-, 1,3-, 1,4-, 1,5-, 1,6- or 1,7-heptylene group, isooctylene, 1,8-octylene group, isononylene group, 1,9-nonylene group, isodecylene group, 1,10-decylene group, 1,11-undecylene group, 1,12-dodecylene group, and the like. Of these, alkylene groups having 1 to 6 carbon atoms are preferred from the viewpoint of wear prevention, and alkylene groups having 1 to 4 carbon atoms are more preferred.
Examples of dicarboxylic acids having 3 to 14 carbon atoms include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanediic acid, and alkyl succinic acid (such as succinic acid having an alkyl group with 1 to 10 carbon atoms).

Specific examples of monomers (t1) include monoesters of hydroxyalkyl (C1-C10) (meth)acrylates and C3-C14 dicarboxylic acids {for example, mono(2-(meth)acryloyloxyethyl) malonate, mono(3-(meth)acryloyloxy-n-propyl) malonate, mono(meth)acryloyloxyisopropyl malonate, mono(4-(meth)acryloyloxy-n-butyl) malonate, mono(meth)acryloyloxyisobutyl malonate, mono(6-(meth)acryloyloxy-n-hexyl) malonate, mono(8-(meth)acryloyloxy-n-octyl) malonate, mono(10-(meth)acryloyloxy-n-decyl) malonate, mono(meth)acryloyloxy-n-decyl) malonate No(meth)acryloyloxyisodecyl, mono(2-(meth)acryloyloxyethyl) succinate, mono(3-(meth)acryloyloxy-n-propyl) succinate, mono(meth)acryloyloxyisopropyl succinate, mono(4-(meth)acryloyloxy-n-butyl) succinate, mono(meth)acryloyloxyisobutyl succinate, mono(6-(meth)acryloyloxy-n-hexyl) succinate, mono(8-(meth)acryloyloxy-n-octyl) succinate, mono(10-(meth)acryloyloxy-n-decyl) succinate, mono(meth)acryloyloxyisodecyl succinate, mono(2-(meth)acryloyloxyethyl) glutanate, mo (3-(meth)acryloyloxy-n-propyl), mono(meth)acryloyloxyisopropyl glutanate, mono(4-(meth)acryloyloxy-n-butyl) glutanate, mono(meth)acryloyloxyisobutyl glutanate, mono(6-(meth)acryloyloxy-n-hexyl) glutanate, mono(8-(meth)acryloyloxy-n-octyl) glutanate, mono(10-(meth)acryloyloxy-n-decyl) glutanate, mono(meth)acryloyloxyisodecyl glutanate, mono(2-(meth)acryloyloxyethyl) adipic acid, mono(3-(meth)acryloyloxy-n-propyl) adipic acid, mono(meth)acryloyloxy Cyisopropyl, adipic acid mono(4-(meth)acryloyloxy-n-butyl), adipic acid mono(meth)acryloyloxyisobutyl, adipic acid mono(6-(meth)acryloyloxy-n-hexyl), adipic acid mono(8-(meth)acryloyloxy-n-octyl), adipic acid mono(10-(meth)acryloyloxy-n-decyl), adipic acid mono(meth)acryloyloxyisodecyl, adipic acid mono(2-(meth)acryloyloxyethyl), pimelic acid mono(3-(meth)acryloyloxy-n-propyl), pimelic acid mono(meth)acryloyloxyisopropyl, pimelic acid mono(4-(meth)acryloyloxy-n-butyl), pimelic acid Mono(meth)acryloyloxyisobutyl pimeric acid, mono(6-(meth)acryloyloxy-n-hexyl) pimelic acid, mono(8-(meth)acryloyloxy-n-octyl) pimelic acid, mono(10-(meth)acryloyloxy-n-decyl) pimelic acid, mono(meth)acryloyloxyisodecyl pimelic acid, mono(2-(meth)acryloyloxyethyl) suberic acid, mono(3-(meth)acryloyloxy-n-propyl) suberic acid, mono(meth)acryloyloxyisopropyl suberic acid, mono(4-(meth)acryloyloxy-n-butyl) suberic acid, mono(meth)acryloyloxyisobutyl suberic acid, mono(6-( (meth)acryloyloxy-n-hexyl, (8-(meth)acryloyloxy-n-octyl), (10-(meth)acryloyloxy-n-decyl), (meth)acryloyloxyisodecyl, (2-(meth)acryloyloxyethyl), (3-(meth)acryloyloxy-n-propyl), (meth)acryloyloxyisopropyl, (4-(meth)acryloyloxy-n-butyl), (meth)acryloyloxyisobutyl, (6-(meth)acryloyloxy-n-hexyl), (8-(meth) ) Acryloyloxy-n-octyl), azelaic acid mono(10-(meth)acryloyloxy-n-decyl), azelaic acid mono(meth)acryloyloxyisodecyl, sebaic acid mono(2-(meth)acryloyloxyethyl), sebaic acid mono(3-(meth)acryloyloxy-n-propyl), sebaic acid mono(meth)acryloyloxyisopropyl, sebaic acid mono(4-(meth)acryloyloxy-n-butyl), sebaic acid mono(meth)acryloyloxyisobutyl, sebaic acid mono(6-(meth)acryloyloxy-n-hexyl), sebaic acid mono(8-(meth)acryloyloxy-n-octyl), sebaic acid mono(10-(meth)acryloyloxy {-n-decyl), mono(meth)acryloyloxyisodecyl sebacate, mono(2-(meth)acryloyloxyethyl) dodecanediol, mono(3-(meth)acryloyloxy-n-propyl) dodecanediol, mono(meth)acryloyloxyisopropyl dodecanediol, mono(4-(meth)acryloyloxy-n-butyl) dodecanediol, mono(meth)acryloyloxyisobutyl dodecanediol, mono(6-(meth)acryloyloxy-n-hexyl) dodecanediol, mono(8-(meth)acryloyloxy-n-octyl) dodecanediol, mono(10-(meth)acryloyloxy-n-decyl) dodecanediol, mono(meth)acryloyloxyisodecyl dodecanediol, etc.}

Monoesterified compounds of alkylene (C2-C4) oxide adducts (1-10 moles added) of hydroxyalkyl (C1-C10) (meth)acrylates and dicarboxylic acids with C3-C14 {for example, monoesterified compounds of malonic acid and (meth)acryloyloxyethyl polyethylene glycol (1-10 moles of ethylene oxide added), monoesterified compounds of malonic acid and (meth)acryloyloxy-n-propyl polyethylene glycol (1-10 moles of ethylene oxide added), monoesterified compounds of malonic acid and (meth)acryloyloxyisopropyl polyethylene glycol (1-10 moles of ethylene oxide added), monoesterified compounds of malonic acid and (meth)acryloyloxy-n-butyl polyethylene glycol (1-10 moles of ethylene oxide added), monoesterified compounds of malonic acid and (meth)acryloyloxyisobutyl polyethylene glycol Monoesterified succinic acid with (1-10 moles of ethylene oxide added), monoesterified succinic acid with (meth)acryloyloxyethyl polyethylene glycol (1-10 moles of ethylene oxide added), monoesterified succinic acid with (meth)acryloyloxy-n-propyl polyethylene glycol (1-10 moles of ethylene oxide added), monoesterified succinic acid with (meth)acryloyloxyisopropyl polyethylene glycol (1-10 moles of ethylene oxide added), monoesterified succinic acid with (meth)acryloyloxy-n-butyl polyethylene glycol (1-10 moles of ethylene oxide added), monoesterified succinic acid with (meth)acryloyloxyisobutyl polyethylene glycol (1-10 moles of ethylene oxide added), monoesterified glutanic acid with (meth)acryloyloxyethyl polyethylene Monoesterified compounds of glycol (with 1-10 moles of ethylene oxide added), monoesterified compounds of glutanic acid and (meth)acryloyloxy-n-propyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified compounds of glutanic acid and (meth)acryloyloxyisopropyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified compounds of glutanic acid and (meth)acryloyloxy-n-butyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified compounds of glutanic acid and (meth)acryloyloxyisobutyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified compounds of adipic acid and (meth)acryloyloxyethyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified compounds of adipic acid and meth)acryloyloxy Monoesterified product of n-propyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified product of adipic acid and meth)acryloyloxyisopropyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified product of adipic acid and (meth)acryloyloxy-n-butyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified product of adipic acid and (meth)acryloyloxyisobutyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified product of pimelic acid and (meth)acryloyloxyethyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified product of pimelic acid and (meth)acryloyloxy-n-propyl polyethylene glycol (with 1-10 moles of ethylene oxide added), pimelic acid and Monoesterified (meth)acryloyloxyisopropyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified pimlic acid with (meth)acryloyloxy-n-butyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified pimlic acid with (meth)acryloyloxyisobutyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified suberic acid with (meth)acryloyloxyethyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified suberic acid with (meth)acryloyloxy-n-propyl polyethylene glycol (with 1-10 moles of ethylene oxide added), and suberic acid with (meth)acryloyloxyisopropyl polyethylene glycol (with 1-10 moles of ethylene oxide added). Monoesterified products of suberic acid and (meth)acryloyloxy-n-butyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified products of suberic acid and (meth)acryloyloxyisobutyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified products of azelaic acid and (meth)acryloyloxyethyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified products of azelaic acid and (meth)acryloyloxy-n-propyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified products of azelaic acid and (meth)acryloyloxyisopropyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified products of azelaic acid and (meth)acryloyloxy-n-butyl polyethylene glycol ( Monoesterified with (1-10 moles of ethylene oxide added), monoesterified with azelaic acid and (meth)acryloyloxyisobutyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified with sebacic acid and (meth)acryloyloxyethyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified with sebacic acid and (meth)acryloyloxy-n-propyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified with sebacic acid and (meth)acryloyloxyisopropyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified with sebacic acid and (meth)acryloyloxy-n-butyl polyethylene glycol (with 1-10 moles of ethylene oxide added), monoesterified with sebacic acid and (meth)acryloyloxyisobutyl Examples include monoesterified polyethylene glycol (with 1 to 10 moles of ethylene oxide added), monoesterified dodecanediic acid with (meth)acryloyloxyethyl polyethylene glycol (with 1 to 10 moles of ethylene oxide added), monoesterified dodecanediic acid with (meth)acryloyloxy-n-propyl polyethylene glycol (with 1 to 10 moles of ethylene oxide added), monoesterified dodecanediic acid with (meth)acryloyloxyisopropyl polyethylene glycol (with 1 to 10 moles of ethylene oxide added), monoesterified dodecanediic acid with (meth)acryloyloxy-n-butyl polyethylene glycol (with 1 to 10 moles of ethylene oxide added), monoesterified dodecanediic acid with (meth)acryloyloxyisobutyl polyethylene glycol (with 1 to 10 moles of ethylene oxide added), etc.

Monomer (t1) can be obtained, for example, by monoesterification of an alkyldicarboxylic acid having 3 to 14 carbon atoms (e.g., malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and alkyl (1 to 10 carbon atoms) succinic acid, etc.) or their anhydrides or lower alkyl (1 to 4 carbon atoms) esters with hydroxyalkyl (1 to 10 carbon atoms) (meth)acrylate or a 1 to 10 molar adduct of hydroxyalkyl (1 to 10 carbon atoms) (meth)acrylate. Alternatively, it can be obtained by monoesterification of an alkyldicarboxylic acid having 3 to 14 carbon atoms or their anhydrides or lower alkyl (1 to 4 carbon atoms) esters with hydroxyalkyl (1 to 10 carbon atoms) (meth)acrylamide or a 1 to 10 molar adduct of hydroxyalkyl (1 to 10 carbon atoms) (meth)acrylamide.
Furthermore, monomers (t1) such as mono(2-acryloyloxyethyl) succinate (manufactured by Tokyo Chemical Industry Co., Ltd.) and mono(2-acryloyloxyethyl) succinate (product name "HOA-MS(N)", manufactured by Kyoeisha Chemical Co., Ltd.) are commercially available and can be obtained.

The monomer (t2) is a monomer having 1 to 5 carboxyl groups, represented by the general formula (5) above.
In general formula (5), R ¹² is either a hydrogen atom or a methyl group, and of these, both a hydrogen atom and a methyl group are preferred from the viewpoint of wear prevention.

In general formula (5), ^-X7- is a group represented by -O- or NH-, of which -O- is preferred from the viewpoint of wear prevention.

In general formula (5), R ¹³ is an alkylene group having 1 to 10 carbon atoms. Examples of alkylene groups having 1 to 10 carbon atoms include methylene, ethylene, isopropylene, 1,2- or 1,3-propylene, isobutylene, 1,2-, 1,3- or 1,4-butylene, isopentylene, 1,2-, 1,3-, 1,4- or 1,5-pentylene, isohexylene, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexylene, isoheptylene, 1,2-, 1,3-, 1,4-, 1,5-, 1,6- or 1,7-heptylene, isooctylene, 1,8-octylene, isononylene, 1,9-nonylene, isodecylene, and 1,10-decylene.
Of these, ethylene groups, 1,2-propylene groups, and 1,3-propylene groups are preferred from the viewpoint of wear prevention, and ethylene groups are even more preferred.

In general formula (5), R ¹⁴ O is an alkylene oxy group having 2 to 4 carbon atoms. Examples of alkylene oxy groups having 2 to 4 carbon atoms include ethylene oxy group, propylene oxy group, and butylene oxy group. Examples of propylene groups in the propylene oxy group include 1,2-propylene group and 1,3-propylene group, and examples of butylene groups in the butylene oxy group include 1,2-butylene group, 1,3-butylene group, and 1,4-butylene group.
The alkylene oxy group is preferably an ethylene oxy group and a propylene oxy group from the viewpoint of wear prevention, and more preferably an ethylene oxy group.

In general formula (5), v is an integer from 0 to 10, preferably an integer from 0 to 7, more preferably an integer from 0 to 5, and particularly preferably an integer from 0 to 3, from the viewpoint of wear prevention.
If v is 2 or greater, the multiple ^R14O molecules may be the same or different.

In general formula (5), R ¹⁵ is independently either a hydrogen atom or a carboxyl group, with at least one being a carboxyl group. Of these, from the viewpoint of wear prevention, there are preferably 1 to 5 carboxyl groups, more preferably 1 to 4 carboxyl groups, and particularly preferably 1 to 3.

Specific examples of monomers (t2) include monohydroxyethyl (meth)acrylate phthalate, monohydroxy-n-propyl (meth)acrylate phthalate, monohydroxyisopropyl (meth)acrylate phthalate, monohydroxy-n-butyl (meth)acrylate phthalate, monohydroxyisobutyl (meth)acrylate phthalate, monohydroxy-n-hexyl (meth)acrylate phthalate, monohydroxy-n-octyl (meth)acrylate phthalate, monohydroxy-n-decyl (meth)acrylate phthalate, monoesterified phthalates of phthalates and hydroxyalkyl (C2-C10) (meth)acrylates with 1-10 molar alkylene (C2-C4) oxide adducts, monohydroxyethyl (meth)acrylate trimellitate, monohydroxy-n-propyl (meth)acrylate trimellitate, monohydroxyisopropyl (meth)acrylate trimellitate, and Monohydroxy-n-butyl (meth)acrylate trimellitate, monohydroxyisobutyl (meth)acrylate trimellitate, monohydroxy-n-hexyl (meth)acrylate trimellitate, monohydroxy-n-octyl (meth)acrylate trimellitate, monohydroxy-n-decyl (meth)acrylate trimellitate, monoesterified trimellitate with 1-10 molar alkylene (2-4 carbon atoms) oxide adducts of hydroxyalkyl (2-10 carbon atoms) (meth)acrylate, monohydroxyethyl (meth)acrylate pyromellidate, monohydroxy-n-propyl (meth)acrylate pyromellidate, monohydroxyisopropyl (meth)acrylate pyromellidate, monohydroxy-n-butyl (meth)acrylate pyromellidate, monohydroxyisobutyl (meth)acrylate pyromellidate, monohydroxy-n-hexyl (meth)acrylate pyromellidate Rate, pyromelidic acid monohydroxy-n-octyl (meth)acrylate, pyromelidic acid monohydroxy-n-decyl (meth)acrylate, monoesterified pyromelidic acid with 1-10 molar alkylene (C2-C4) oxide adducts of hydroxyalkyl (C2-C10) (meth)acrylate, benzenepentacarboxylic acid monohydroxyethyl (meth)acrylate, benzenepentacarboxylic acid monohydroxy-n-propyl (meth)acrylate, benzenepentacarboxylic acid monohydroxyisopropyl (meth)acrylate, benzenepentacarboxylic acid monohydroxy-n-butyl (meth)acrylate, benzenepentacarboxylic acid monohydroxyisobutyl (meth)acrylate, benzenepentacarboxylic acid monohydroxy-n-hexyl (meth)acrylate, benzenepentacarboxylic acid monohydroxy-n-octyl (meth)acrylate, benzenepentacarboxylic acid mono Examples include hydroxy-n-decyl (meth)acrylate, monoesterified benzenepentacarboxylic acid with 1-10 molar alkylene (C2-C4) oxide adducts of hydroxyalkyl (C2-C10) (meth)acrylate, monohydroxyethyl (meth)acrylate mellitate, monohydroxy-n-propyl (meth)acrylate mellitate, monohydroxyisopropyl (meth)acrylate mellitate, monohydroxy-n-butyl (meth)acrylate mellitate, monohydroxyisobutyl (meth)acrylate mellitate, monohydroxy-n-hexyl (meth)acrylate mellitate, monohydroxy-n-octyl (meth)acrylate mellitate, monohydroxy-n-decyl (meth)acrylate mellitate, and monoesterified mellit acid with 1-10 molar alkylene (C2-C4) oxide adducts of hydroxyalkyl (C2-C10) (meth)acrylate.

Monomer (t2) can be obtained, for example, by monoesterification of aromatic polyvalent (2-6 valent) carboxylic acids (e.g., phthalic acid, isophthalic acid, terephthalic acid, hemimellitic acid, trimellitic acid, trimesic acid, merophanic acid, prenitic acid, pyromellitic acid, and melitic acid, etc.) or their anhydrides or lower alkyl (C1-4) esters with hydroxyalkyl (C1-10) (meth)acrylate or a 1-10 molar adduct of hydroxyalkyl (C1-10) (meth)acrylate with alkylene (C2-4) oxide. Alternatively, it can be obtained by monoesterification of aromatic polyvalent (2-6 valent) carboxylic acids or their anhydrides or lower alkyl (C1-4) esters with hydroxyalkyl (C1-10) (meth)acrylamide or a 1-10 molar adduct of hydroxyalkyl (C1-10) (meth)acrylamide with alkylene (C2-4) oxide.
Furthermore, monomers (t2) such as mono(2-methacryloyloxyethyl) phthalate (manufactured by Tokyo Chemical Industry Co., Ltd.) and mono(2-acryloyloxyethyl) phthalate (product name "HOA-MPL(N)", manufactured by Kyoeisha Chemical Co., Ltd.) are commercially available and can be obtained.

The monomer (t3) is a monomer having 1 to 5 carboxyl groups, represented by the general formula (6) above.
In general formula (6), R ¹⁶ is either a hydrogen atom or a methyl group, and of these, both a hydrogen atom and a methyl group are preferred from the viewpoint of wear prevention.

In general formula (6), ^-X8- is a group represented by -O- or NH-, of which -O- is preferred from the viewpoint of wear prevention.

In general formula (6), R ¹⁷ is an alkylene group having 1 to 10 carbon atoms.
Examples of alkylene groups having 1 to 10 carbon atoms include methylene, ethylene, isopropylene, 1,2- or 1,3-propylene, isobutylene, 1,2-, 1,3- or 1,4-butylene, isopentylene, 1,2-, 1,3-, 1,4- or 1,5-pentylene, isohexylene, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexylene, isoheptylene, 1,2-, 1,3-, 1,4-, 1,5-, 1,6- or 1,7-heptylene, isooctylene, 1,8-octylene, isononylene, 1,9-nonylene, isodecylene, and 1,10-decylene.
Of these, ethylene groups, 1,2-propylene groups, and 1,3-propylene groups are preferred from the viewpoint of wear prevention, and ethylene groups are even more preferred.

In general formula (6), R ¹⁸ O is an alkylene oxy group having 2 to 4 carbon atoms. Examples of alkylene oxy groups having 2 to 4 carbon atoms include ethylene oxy group, propylene oxy group, and butylene oxy group. Examples of propylene groups in the propylene oxy group include 1,2-propylene group and 1,3-propylene group, and examples of butylene groups in the butylene oxy group include 1,2-butylene group, 1,3-butylene group, and 1,4-butylene group. From the viewpoint of wear prevention, the alkylene oxy group is preferably an ethylene oxy group and a propylene oxy group, and more preferably an ethylene oxy group.

In general formula (6), r is an integer from 0 to 10, preferably an integer from 0 to 7, more preferably an integer from 0 to 5, and particularly preferably an integer from 0 to 3, from the viewpoint of wear prevention.
If r is 2 or greater, the multiple ^R18O atoms may be the same or different.

In general formula (6), R ¹⁹ is independently either a hydrogen atom or a carboxyl group, with at least one being a carboxyl group. Of these, from the viewpoint of wear prevention, there are preferably 1 to 5 carboxyl groups, more preferably 1 to 4 carboxyl groups, and particularly preferably 1 to 3.
Specific examples of monomers (t3) include monohydroxyethyl (meth)acrylate hexahydrophthalate, monohydroxy-n-propyl (meth)acrylate hexahydrophthalate, monohydroxyisopropyl (meth)acrylate hexahydrophthalate, monohydroxy-n-butyl (meth)acrylate hexahydrophthalate, monohydroxyisobutyl (meth)acrylate hexahydrophthalate, monohydroxy-n-hexyl (meth)acrylate hexahydrophthalate, monohydroxy-n-octyl (meth)acrylate hexahydrophthalate, and monohydroxy-n-decyl (meth)acrylate hexahydrophthalate. Lilate, monoesterified hexahydrophthalic acid with hydroxyalkyl (C1-C10) (meth)acrylates and 1-10 molar alkylene (C2-C4) oxide adducts, 1,2,4-cyclohexanetricarboxylic acid monohydroxyethyl (meth)acrylate, 1,2,4-cyclohexanetricarboxylic acid monohydroxy-n-propyl (meth)acrylate, 1,2,4-cyclohexanetricarboxylic acid monohydroxyisopropyl (meth)acrylate, 1,2,4-cyclohexanetricarboxylic acid monohydroxy-n-butyl (meth)acrylate, 1,2,4-cyclohexanetricarboxylic acid monohydroxy Cyisobutyl (meth)acrylate, 1,2,4-cyclohexanetricarboxylic acid monohydroxy-n-hexyl (meth)acrylate, 1,2,4-cyclohexanetricarboxylic acid monohydroxy-n-octyl (meth)acrylate, 1,2,4-cyclohexanetricarboxylic acid monohydroxy-n-decyl (meth)acrylate, monoesterified products of 1,2,4-cyclohexanetricarboxylic acid and hydroxyalkyl (C1-C10) (meth)acrylate with 1-10 molar alkylene (C2-C4) oxide adducts, 1,2,4,5-cyclohexanetetracarboxylic acid monohydroxyethyl (meth)acrylate, 1,2,4,5-cyclohexanetetracarboxylic acid monohydroxy-n-propyl (meth)acrylate, 1,2,4,5-cyclohexanetetracarboxylic acid monohydroxyisopropyl (meth)acrylate, 1,2,4,5-cyclohexanetetracarboxylic acid monohydroxy-n-butyl (meth)acrylate, 1,2,4,5-cyclohexanetetracarboxylic acid monohydroxyisobutyl (meth)acrylate, 1,2,4,5-cyclohexanetetracarboxylic acid monohydroxy-n-hexyl (meth)acrylate, 1,2,4,5-cyclohexanetetracarboxylic acid monohydroxy-n-octyl (meth)acrylate 1,2,4,5-cyclohexanetetracarboxylic acid monohydroxy-n-decyl (meth)acrylate, monoesterified 1,2,4,5-cyclohexanetetracarboxylic acid with 1-10 molar alkylene (C2-C4) oxide adducts of hydroxyalkyl (C1-C10) (meth)acrylate, 1,2,3,4,5-cyclohexanepentacarboxylic acid monohydroxyethyl (meth)acrylate, 1,2,3,4,5-cyclohexanepentacarboxylic acid monohydroxy-n-propyl (meth)acrylate, 1,2,3,4,5-cyclohexanepentacarboxylic acid monohydroxyisopropyl (meth)acrylate , 1,2,3,4,5-cyclohexanepentacarboxylic acid monohydroxy-n-butyl (meth)acrylate, 1,2,3,4,5-cyclohexanepentacarboxylic acid monohydroxyisobutyl (meth)acrylate, 1,2,3,4,5-cyclohexanepentacarboxylic acid monohydroxy-n-hexyl (meth)acrylate, 1,2,3,4,5-cyclohexanepentacarboxylic acid monohydroxy-n-octyl (meth)acrylate, 1,2,3,4,5-cyclohexanepentacarboxylic acid monohydroxy-n-decyl (meth)acrylate, 1,2,3,4,5-cyclohexanepentacarboxylic acid and hydroxyalkyl ( Monoesterified compounds of (meth)acrylates (1-10 carbon atoms) with 1-10 molar adducts of alkylene (2-4 carbon atoms) oxide, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid monohydroxyethyl (meth)acrylate, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid monohydroxy-n-propyl (meth)acrylate, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid monohydroxyisopropyl (meth)acrylate, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid monohydroxy-n-butyl (meth)acrylate, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid Examples include monohydroxyisobutyl (meth)acrylate benzoate, monohydroxy-n-hexyl (meth)acrylate 1,2,3,4,5,6-cyclohexanehexacarboxylic acid, monohydroxy-n-octyl (meth)acrylate 1,2,3,4,5,6-cyclohexanehexacarboxylic acid, monohydroxy-n-decyl (meth)acrylate 1,2,3,4,5,6-cyclohexanehexacarboxylic acid, and monoesterified products of 1,2,3,4,5,6-cyclohexanehexacarboxylic acid with 1 to 10 molar alkylene (carbon 2 to carbon 4) oxide adducts of hydroxyalkyl (carbon 1 to carbon 10) (meth)acrylate.

The monomer (t3) is, for example, a cyclohexane polyvalent (2-6 valent) carboxylic acid (e.g., 1,2-cyclohexanedicarboxylic acid (also written as hexahydrophthalic acid), 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2,3-cyclohexanetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, 1,2,3,4-cyclohexanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid It can be obtained by monoesterification of an acid (such as 1,2,3,5-cyclohexanetetracarboxylic acid, 1,2,3,4,5-cyclohexanepentacarboxylic acid, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid, etc.) or their anhydrides or lower alkyl (C1-C4) esters with hydroxyalkyl (C1-C10) (meth)acrylate or a 1-10 molar adduct of hydroxyalkyl (C1-C10) (meth)acrylate and alkylene (C2-C4) oxide. Alternatively, it can be obtained by monoesterification of polyvalent cyclohexane or its anhydrides or lower alkyl (C1-C4) esters with hydroxyalkyl (C1-C10) (meth)acrylamide or a 1-10 molar adduct of hydroxyalkyl (C1-C10) (meth)acrylamide and alkylene (C2-C4) oxide.
Furthermore, monomers (t3) such as hexahydrophthalate mono(2-methacryloyloxyethyl) (manufactured by Tokyo Chemical Industry Co., Ltd.) and hexahydrophthalate mono(2-acryloyloxyethyl) (product name "Light Acrylate HOA-HH(N)", manufactured by Kyoeisha Chemical Co., Ltd.) are commercially available and can be obtained.

The weight percentage of monomer (a) constituting copolymer (A) is preferably 10 to 45% by weight, more preferably 18 to 40% by weight, then even more preferably 22 to 36% by weight, and particularly preferably 28 to 36% by weight, based on the total weight of the constituent monomers of (A), from the viewpoint of base oil solubility and wear prevention properties.
The weight percentage of monomer (b) constituting copolymer (A) is preferably 0.5 to 20% by weight, more preferably 2 to 15% by weight, then even more preferably 2 to 10% by weight, and particularly preferably 3 to 10% by weight, based on the total weight of the constituent monomers of (A), from the viewpoint of wear prevention, low copper corrosion, and electrical insulation.
The weight percentage of monomer (c) constituting copolymer (A) is preferably 50 to 85% by weight, more preferably 53 to 75% by weight, even more preferably 53 to 70% by weight, then even more preferably 55 to 67% by weight, and particularly preferably 58 to 67% by weight, based on the total weight of the constituent monomers of (A), from the viewpoint of base oil solubility and wear prevention.
The weight percentage of monomers (t) constituting the copolymer (A) is preferably 0.5 to 17.5% by weight, more preferably 1.5 to 13% by weight, then even more preferably 1.5 to 10% by weight, and particularly preferably 3 to 10% by weight, based on the total weight of the constituent monomers of (A), from the viewpoint of wear prevention, low copper corrosion resistance, and electrical insulation.
From the viewpoint of wear prevention, the total weight ratio of monomers (d) to (f) constituting copolymer (A) is preferably 20% by weight or less, more preferably 15% by weight or less, then even more preferably 10% by weight or less, and particularly preferably 7% by weight or less, based on the total weight of the constituent monomers of (A).
From the viewpoint of wear prevention, the total weight ratio of monomers (g) to (n) constituting copolymer (A) is preferably 10% by weight or less, more preferably 7% by weight or less, and particularly preferably 5% by weight or less, based on the total weight of the constituent monomers of (A).

In the present invention, the weight ratio (a/b) of monomer (a) to the weight of monomer (b) in the monomer constituting copolymer (A) is 0.5 to 80.
A weight ratio (a/b) of 0.5 or higher results in good copper compatibility (low copper corrosion) and electrical insulation, while a ratio of 80 or lower provides excellent wear prevention. In the present invention, by including monomer (a) and monomer (b) as constituent monomers in the above weight ratio in copolymer (A), it is presumed that copper corrosion is suppressed, the carboxyl group derived from monomer (b) enhances the adsorption force to the metal, and this, combined with the adsorption force from the side chain {-(-C(=O) ^-R2 - ^X3- ) _p - ^R3 } portion derived from monomer (a), can further enhance the wear prevention effect.
The weight ratio (a/b) is preferably 0.5 to 20, more preferably 1 to 10, and particularly preferably 2 to 8.

In the present invention, the total weight ratio of monomers (a) and monomer (b) constituting copolymer (A) is preferably 15 to 50% by weight, more preferably 25 to 47% by weight, even more preferably 30 to 42% by weight, and particularly preferably 33 to 40% by weight, based on the total weight of the constituent monomers of (A), from the viewpoint of base oil solubility and wear prevention properties.
In the present invention, the total weight ratio of monomers (a), monomer (b), and monomer (c) constituting copolymer (A) is preferably 83% by weight or more, more preferably 87% by weight or more, and particularly preferably 95% by weight or more, from the viewpoint of wear prevention.

The acid value of copolymer (A) is preferably 1.0 to 38 mg KOH/g, more preferably 3.8 to 28 mg KOH/g, and particularly preferably 5.8 to 19 mg KOH/g, from the viewpoint of wear prevention, low copper corrosion, and electrical insulation.
The acid value of (A) can be measured in accordance with JIS K2501.

The SP value of copolymer (A) is preferably 8.5 to 11.5 (cal/ ^cm³ ) ^1/2 , more preferably 8.7 to 11.0 (cal/cm³) 1/2, more preferably 8.9 to 10.5 (cal/ ^cm³ ) ^1/2 , and particularly preferably 9.2 to 10.2 (cal/ ^cm³ ) ^1/2 , from the viewpoint of base oil solubility ^{and viscosity index} improvement effect.

The SP value of copolymer (A) is calculated by determining the SP value of the constituent units derived from each monomer constituting (A) using the SP value calculation method described above (the structure in which the vinyl groups contained in each monomer constituting (A) become single bonds through polymerization reactions), and then taking the arithmetic mean value based on the weight fraction of each constituent monomer at the time of preparation. For example, if the monomer is methyl methacrylate, the constituent units derived from methyl methacrylate consist of two _CH3 groups, one _CH2 group, one C group, and one _CO2 group as an atomic group. Therefore, using the following formula, the SP value of the constituent units derived from methyl methacrylate is 9.933 (cal/ ^cm³ ) ^1/2 . Similarly, calculating, the SP value of the constituent units derived from ethyl methacrylate is 9.721 (cal/ ^cm³ ) ^1/2 .
ΣΔe _i =1125×2+1180+350+4300=8080
Σv _i =33.5×2+16.1-19.2+18.0=81.9
δ=(8080/81.9) ^1/2 =9.933(cal/cm ³ ) ^1/2
When the polymer is a polymer of 50% by weight methyl methacrylate and 50% by weight ethyl methacrylate, the SP value of the polymer is calculated by taking the arithmetic mean based on the weight fraction of the SP values of the constituent units derived from each monomer, as shown below.
SP value of polymer = (9.933 × 50 + 9.721 × 50) / 100 = 9.827 (cal/ ^cm³ ) ^1/2
The SP value of polymer (A) can be adjusted to a desired range by appropriately adjusting the monomers and their weight fractions used. Specifically, the SP value can be reduced by using a large amount of monomers with long alkyl groups, and increased by using a large amount of monomers with short alkyl groups.

The weight-average molecular weight (hereinafter abbreviated as Mw) of copolymer (A) is preferably 0.5 million to 500,000, more preferably 0.5 million to 100,000, and particularly preferably 10,000 to 50,000, from the viewpoint of wear resistance.

Copolymer (A) can be obtained by known manufacturing methods, specifically by solution polymerization of the monomer in a solvent in the presence of a polymerization catalyst.
Examples of solvents include toluene, xylene, alkylbenzenes having 9 to 10 carbon atoms, methyl ethyl ketone, ethyl acetate, 2-propanol, and base oils described later.
Polymerization catalysts include azo catalysts (such as azobisisobutyronitrile and azobisvaleronitrile), peroxide catalysts (such as benzoyl peroxide, cumyl peroxide, and lauryl peroxide), and redox catalysts (such as a mixture of benzoyl peroxide and a tertiary amine). Furthermore, known chain transfer agents (such as alkyl mercaptans having 2 to 20 carbon atoms) can be used as needed.
The polymerization temperature is preferably 25 to 140°C, and more preferably 50 to 120°C. In addition to the above solution polymerization, (A) can also be obtained by bulk polymerization, emulsion polymerization, or suspension polymerization.
The polymerization form of copolymer (A) may be either a random addition copolymer or an alternating copolymer, and may also be either a graft copolymer or a block copolymer.

The anti-wear agent of the present invention may contain the copolymer (A), but may also contain a base oil from the viewpoint of handling (ease of addition to lubricating oil composition, etc.).
Examples of base oils include mineral oils (solvent-refined oils, paraffin oils, high viscosity index oils containing isoparaffins, high viscosity index oils obtained by hydrocracking of isoparaffins, and naphthenic oils, etc.), synthetic lubricants [hydrocarbon-based synthetic lubricants (poly-α-olefin-based synthetic lubricants, etc.) and ester-based synthetic lubricants, etc.], and mixtures thereof. Of these, mineral oils and hydrocarbon-based synthetic lubricants are preferred from the viewpoint of electrical insulation.

The content of copolymer (A) in the anti-wear agent is preferably 20 to 90% by weight, and more preferably 30 to 80% by weight, based on the weight of the anti-wear agent, from the viewpoint of handling (ease of addition to lubricating oil composition, etc.).
The base oil content in the anti-wear agent is preferably 10 to 80% by weight, and more preferably 20 to 70% by weight, based on the weight of the anti-wear agent, from the viewpoint of handling (ease of addition to lubricating oil composition, etc.).

The anti-wear agent of the present invention has low copper corrosiveness and high anti-wear effect, making it suitable for use in gear oil (differential oil and industrial gear oil, etc.), MTF, transmission oil [ATF and belt-CVTF, etc.], traction oil (toroidal-CVTF, etc.), shock absorber oil, power steering oil, hydraulic oil (construction machinery hydraulic oil and industrial hydraulic oil, etc.), and engine oil, among others. It is particularly preferred for use as an anti-wear agent in transmission oil, electric motor oil, and dual-purpose oil for transmissions and electric motors in electric vehicles or hybrid vehicles. It is especially preferred for use as an anti-wear agent in dual-purpose oil for transmissions and electric motors in electric vehicles or hybrid vehicles.

<Lubricating oil composition>
The lubricating oil composition of the present invention contains the anti-wear agent and base oil of the present invention. If the anti-wear agent contains a base oil, the same base oil as the base oil in the anti-wear agent may be used, or a different base oil may be used.
Examples of base oils used in lubricating oil compositions include mineral oils (solvent-refined oils, paraffin oils, high viscosity index oils containing isoparaffins, high viscosity index oils obtained by hydrocracking of isoparaffins, and naphthenic oils, etc.), synthetic lubricating oils [hydrocarbon-based synthetic lubricating oils (poly-α-olefin-based synthetic lubricating oils, etc.) and ester-based synthetic lubricating oils, etc.] and mixtures thereof. Of these, mineral oils and hydrocarbon-based synthetic lubricating oils are preferred from the viewpoint of insulating properties.

The kinematic viscosity of the base oil at 100°C (measured according to JIS-K2283) is preferably 1 to 10 ^mm² /s, and more preferably 1 to 4 ^mm² /s, from the viewpoint of the solubility of copolymer (A).
The viscosity index of the base oil (measured according to JIS-K2283) is preferably 90 or higher, and more preferably 100 or higher, from the viewpoint of improving the viscosity index.

The cloud point of the base oil (measured according to JIS-K2269) is preferably -5°C or lower, and more preferably -15°C or lower. A cloud point within this range indicates good low-temperature viscosity of the lubricating oil composition.

The absolute value (ΔSP) of the difference between the SP value of copolymer (A) in the lubricating oil composition and the SP value of the base oil is preferably 0.5 to 3.2 (cal/ ^cm³ ) ^1/2 , more preferably 0.6 to 2.5 (cal/ ^cm³ ) ^1/2 , particularly preferably 0.6 to 2.1 (cal/ ^cm³ ) ^1/2 , and most preferably 0.7 to 1.7 (cal/ ^cm³ ) ^1/2 , from the viewpoint of compatibility.

The content of copolymer (A) in the lubricating oil composition of the present invention is preferably 0.1 to 30% by weight, more preferably 0.1 to 20% by weight, and particularly preferably 0.1 to 10% by weight, based on the weight of the lubricating oil composition and from the viewpoint of wear prevention.

The lubricating oil composition of the present invention is suitably used in gear oil (differential oil and industrial gear oil, etc.), MTF, transmission oil [ATF and belt-CVTF, etc.], traction oil (toroidal-CVTF, etc.), shock absorber oil, power steering oil, hydraulic oil (construction machinery hydraulic oil and industrial hydraulic oil, etc.), and engine oil, and is particularly useful as transmission oil, electric motor oil, and dual-purpose oil for transmissions and electric motors in electric vehicles or hybrid vehicles, and especially as a dual-purpose oil for transmissions and electric motors in electric vehicles or hybrid vehicles.

The lubricating oil composition of the present invention may contain various other additives besides the anti-wear agent of the present invention. Examples of other additives include at least one selected from the group consisting of viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, extreme pressure agents, defoamers, anti-emulsifiers, corrosion inhibitors, and pour point depressants, and examples of each additive are as follows. Alternatively, multiple additives may be included in the lubricating oil composition as a lubricating oil package additive. Examples of lubricating oil package additives include DI (Detergent Inhibitor) packages.
DI packages are commercially available and can be obtained from companies such as Lubrizol Corporation (for example, the Lubrizol PV series for gasoline vehicles, product name PV1510, etc.), Infinium (for example, Infinium P5741 for engine oil, etc.), Chevron Corporation (for example, OLOA55501, OLOA55503 for passenger car motor oil, etc.), and Afton Chemical Corporation (for example, the HiTEC 9800 series for engine oil, etc.).

(1) Viscosity index improvers:
(C1-7) alkyl (meth)acrylate/(C8-40) linear or branched alkyl (meth)acrylate copolymer, dispersed monomer (amine monomer, etc.)/(C1-7) alkyl (meth)acrylate/(C8-40) linear or branched alkyl (meth)acrylate copolymer, hydroxyl group-containing monomer/(C1-7) alkyl (meth)acrylate/(C8-40) linear or branched alkyl (meth)acrylate copolymer, comb-shaped polymer [(C1-7) alkyl ( [meth)acrylate/(C8-40) linear or branched alkyl (meth)acrylate/polyolefin macromonomer], ethylene/(C1-18) alkyl (meth)acrylate copolymer, alkoxyalkyl (meth)acrylate/polybutylene copolymer macromonomer/(C1-32) linear or branched alkyl (meth)acrylate copolymer, polyisobutylene, polyalkylstyrene, ethylene/propylene copolymer, styrene/maleic acid ester copolymer, styrene/isoprene hydrogenated copolymer, etc.;
(2) Cleaning agent:
Basic, overbasic, or neutral metal salts [overbasic sulfonates (petroleum sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, etc.) or alkaline earth metal salts, etc.], salicylates, phenates, naphthenates, carbonates, phosphonates, and mixtures thereof;
(3) Dispersant:
Succinimides (bis- or mono-polybutenyl succinimides), Mannich condensates, borates, etc.
(4) Antioxidants:
Hindered phenols and aromatic secondary amines, etc.
(5) Oiliness improvers:
Long-chain fatty acids and their esters (oleic acid and oleic acid esters, etc.), long-chain amines and their amides (oleylamine and oleylamide, etc.), etc.
(6) Extreme pressure agents:
Sulfur compounds (mono- or disulfide, sulfoxide, and sulfur phosphide compounds), phosphide compounds, and chlorine compounds (such as chlorinated paraffins);
(7) Antifoaming agent:
Silicone oils, metallic soaps, fatty acid esters, and phosphate compounds, etc.
(8) Antiemulsifiers:
Quaternary ammonium salts (such as tetraalkylammonium salts), sulfated oils, and phosphates (such as phosphates of polyoxyethylene-containing nonionic surfactants), etc.
(9) Corrosion inhibitors:
Nitrogen atom-containing compounds (such as benzotriazole and 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate), etc.
(10) Pour point depressants:
Polyalkyl methacrylate, polyalkyl acrylate, polyalkylstyrene, polyvinyl acetate, etc.

The lubricating oil composition of the present invention may contain friction and wear inhibitors other than the wear inhibitor of the present invention.
(11) Friction and wear modifiers:
Molybdenum-based and zinc-based compounds (such as molybdenum dithiophosphate, molybdenum dithiocarbamate, and zinc dialkyldithiophosphate);

The total content of other additives in the lubricating oil composition is preferably 0.1 to 30% by weight, more preferably 0.3 to 20% by weight, and even more preferably 3 to 10% by weight, based on the weight of the lubricating oil composition.

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

<Manufacturing Example 1> [Manufacturing of Monomer (a-1)]
In a reaction vessel equipped with a temperature controller, stirring blades, vacuum device, Liebig condenser, fractionation column, distillate receiving flask, nitrogen inlet and outlet, 260.3 parts by weight (2.0 mol) of 2-hydroxyethyl methacrylate (hereinafter abbreviated as HEMA), 684.8 parts by weight (6.0 mol) of ε-caprolactone, 3.7 parts by weight (0.03 mol) of hydroquinone monomethyl ether, and 0.27 parts by weight of butyltris(2-ethylhexanoyloxy)tin were added, and the mixture was heated to 115°C while stirring with air flowing through it. The reaction was then carried out at 115°C for 8 hours, and the distillate was separated. The mixture was further cooled to 25°C, and the esterified product was confirmed by ^1H -NMR (yield 100 mol%).
(a-1) is a monomer in which A in general formula (1) is a methacryloyl group, ^-X1- , ^-X2- , and ^-X3- are groups represented by -O-, ^R1 is an ethylene group, the molar mean of p is 3, ^R2 is a pentylene group, and ^R3 is a hydrogen atom, and the SP value is 11.04.

<Manufacturing Example 2> [Manufacturing of Monomer (a-2)]
In a reaction vessel equipped with a temperature controller, stirring blades, vacuum device, Liebig condenser, fractionation column, distillate receiving flask, nitrogen inlet and outlet, 260.3 parts by weight (2.0 mol) of 2-hydroxyethyl methacrylate (HEMA), 913.2 parts by weight (8.0 mol) of ε-caprolactone, 3.7 parts by weight (0.03 mol) of hydroquinone monomethyl ether, and 0.27 parts by weight of butyltris(2-ethylhexanoyloxy)tin were added, and the mixture was heated to 115°C while stirring with air flowing through it. The reaction was then carried out at 115°C for 8 hours, and the distillate was separated. The mixture was further cooled to 25°C, and the esterified product was confirmed by ^1H -NMR (yield 100 mol%).
(a-2) is a monomer in which A in general formula (1) is a methacryloyl group, ^-X1- , ^-X2- , and ^-X3- are groups represented by -O-, ^R1 is an ethylene group, the molar mean of p is 4, ^R2 is a pentylene group, and ^R3 is a hydrogen atom, and the SP value is 10.87.

<Manufacturing Example 3> [Manufacturing of Monomer (a-3)]
In a reaction vessel equipped with a temperature controller, stirring blades, vacuum device, Liebig condenser, fractionation column, distillate receiving flask, nitrogen inlet and outlet, 260.3 parts by weight (2.0 mol) of 2-hydroxyethyl methacrylate (HEMA), 228.3 parts by weight (2.0 mol) of ε-caprolactone, 3.7 parts by weight (0.03 mol) of hydroquinone monomethyl ether, and 0.27 parts by weight of butyltris(2-ethylhexanoyloxy)tin were added, and the mixture was heated to 115°C while stirring with air flowing through it. The reaction was then carried out at 115°C for 8 hours, and the distillate was separated. After further cooling to 25°C, the esterified product was confirmed by ^1H -NMR (yield 53 mol%). Subsequently, 47 mol% of 2-hydroxyethyl methacrylate (HEMA) remaining as an impurity was removed by silica column chromatography.
(a-3) is a monomer in which A in general formula (1) is a methacryloyl group, ^-X1- , ^-X2- , and ^-X3- are groups represented by -O-, ^R1 is an ethylene group, the molar mean of p = 1.9, ^R2 = pentylene group, and ^R3 is a hydrogen atom, and the SP value is 11.36.

<Manufacturing Example 4> [Manufacturing of Monomer (a-4)]
In a reaction vessel equipped with a temperature controller, stirring blades, vacuum device, Liebig condenser, fractionation column, distillate receiving flask, nitrogen inlet and outlet, 232.2 parts by weight (2.0 mol) of 2-hydroxyethyl acrylate (hereinafter abbreviated as HEA), 456.6 parts by weight (4.0 mol) of ε-caprolactone, 3.7 parts by weight (0.03 mol) of hydroquinone monomethyl ether, and 0.27 parts by weight of butyltris(2-ethylhexanoyloxy)tin were added, and the mixture was heated to 115°C while stirring with air flowing through it. The reaction was then carried out at 115°C for 8 hours, and the distillate was separated. After further cooling to 25°C, the esterified product was confirmed by ^1H -NMR (yield 76 mol%). Subsequently, 24 mol% of 2-hydroxyethyl acrylate (HEA) remaining as an impurity was removed by silica column chromatography.
(a-4) is a monomer in which A in general formula (1) is an acryloyl group, ^-X1- , ^-X2- , and ^-X3- are groups represented by -O-, ^R1 is an ethylene group, the molar mean of p is 2.6, ^R2 is a pentylene group, and ^R3 is a hydrogen atom, and has an SP value of 11.30.

<Examples 1-27, Comparative Examples 1-4>
In a reaction vessel equipped with a stirring device, a heating/cooling device, a thermometer, and a nitrogen inlet tube, 185 parts by weight of ethyl acetate, 100 parts by weight of a mixture of various monomers listed in Tables 2-3, and the amounts of dodecyl mercaptan and 2,2'-azobis(2-methylbutyronitrile) listed in Tables 2-3 as initiator and chain transfer agent were added. After purging with nitrogen (gas phase oxygen concentration 100 ppm), the mixture was heated to 76°C under a sealed container while stirring, and the polymerization reaction was carried out at the same temperature for 6 hours.
43 parts by weight of mineral oil [SP value: 8.3 (cal/ ^cm³ ) ^1/2 , kinematic viscosity at 100°C: 4.2 ^mm² /s, viscosity index: 122] were added, the temperature was raised to 120-130°C, and then unreacted monomers and ethyl acetate were removed under reduced pressure (0.027-0.040 MPa) at the same temperature for 2 hours to obtain the anti-wear agents of the present invention (A-1) to (A-27) and comparative anti-wear agents (B-1) to (B-4) containing 70% by weight of the copolymer.

The various monomers listed in Tables 2-3 are as follows:
(a-5): HEMA ε-caprolactone 5 molar adduct (mean molar value of p = 5, SP value 10.75)
(a-6): ε-caprolactone 10 molar adduct of HEA (mean molar value of p = 10, SP value 10.68)
(a-7): HEMA ε-caprolactone 20 molar adduct (mean molar value of p = 20, SP value 11.32)
(a-8): Terminal butyl ester of the ε-caprolactone 4-mol adduct of HEMA (mean molar value of p = 4, SP value 9.96)
(a-9): Terminal butyl ester of the 7-mol ε-caprolactone adduct of HEMA (mean molar value of p = 7, SP value 10.40)
(b-1): ω-carboxypolycaprolactone (with 2 moles of caprolactone added) monoacrylate (Aronix M-5300, manufactured by Toagosei Co., Ltd.) (In general formula (2), R ⁴ is a hydrogen atom, -X ^4- is -O-, R ⁵ is a pentylene group, q=2)
(b-2): β-carboxyethyl acrylate ("β-CEA" manufactured by Daicel Ornex Co., Ltd.) (In general formula (2), R ⁴ is a hydrogen atom, -X ^4- is -O-, R ⁵ is an ethylene group, q=1)
(c-1): Methacrylic acid ester of Neodol 23 (manufactured by Shell Chemicals, a mixture of linear or branched alkyl alcohols with 12 to 13 carbon atoms (weight ratio = linear C12: branched C12: linear C13: branched C13 = 40:10:40:10)) (c-2): n-hexadecyl methacrylate (c-3): n-octadecyl methacrylate (c-4): 2-decyltetradecyl methacrylate (c-5): 2-docylhexadecyl methacrylate (c-6): 2-tetradecyloctadecyl methacrylate (c-7): dodecyl acrylate (c-8): n-octadecyl acrylate (d-1): N,N-dimethylaminoethyl methacrylate (e-1): 2-hydroxyethyl acrylate (e-2): 2-hydroxyethyl methacrylate (e-3): 2-hydroxy-2-methylpropyl methacrylate

<Examples 28-54, Comparative Examples 5-8>
The obtained anti-wear agents (A-1) to (A-27), and the comparative anti-wear agents (B-1) to (B-4) were added to Toyota Motor Corporation's genuine e-transaxle fluid TE in an amount of 2% by weight relative to the weight of the base oil (amount added in terms of solid matter), to obtain lubricating oil compositions (V-1) to (V-27) and (W-1) to (W-4).

<Additional kinematic viscosity>
The kinematic viscosity at 100°C and 40°C for lubricating oil compositions (V-1) to (V-27) and (W-1) to (W-4) was measured according to the method described in JIS-K2283 (2000). The results are shown in Tables 2 and 3 as added kinematic viscosity ( ^mm² /s).

<Viscosity index>
The viscosity indices of lubricating oil compositions (V-1) to (V-27) and (W-1) to (W-4) were measured according to the method described in JIS-K2283 (2000) and are shown in Tables 2 and 3.

The copper corrosiveness, volume resistivity, and wear evaluation of lubricating oil compositions (V-1) to (V-27) and (W-1) to (W-4) were measured using the following method. The results are shown in Tables 2 and 3.

<Copper corrosion>
A copper plate corrosion test was conducted at 150°C for 12 hours, in accordance with JIS K2513:2000 (Petroleum products - Copper plate corrosion test method). The degree of discoloration of the copper plate after the test was compared to the copper plate corrosion standard, and the discoloration number was recorded. Lubricating oil compositions with a discoloration number of "1" were deemed acceptable.

<Volume resistivity>
The volume resistivity of each lubricating oil composition was measured at room temperature using a non-aqueous conductivity meter (Dispersion Technology, model number: DT700).
The higher the volume resistivity, the better the electrical insulation performance; a volume resistivity of 0.5 × ^10¹⁰ Ω·cm or higher indicates good electrical insulation.

<Wear Evaluation>
The tests were conducted in accordance with ASTM D 2783, except for the test conditions described below. Specifically, for each lubricating oil composition, a load of 500 N was applied to a high-speed four-ball tester and rotated for 10 seconds to check for seizure. If seizure did not occur, the load was increased by 10 N and the next test was performed, and the load just before seizure occurred was measured as the maximum non-seizure load (N). A larger value indicates that seizure is less likely to occur and that the wear prevention effect is superior.
<Measurement conditions>
Equipment: Space Creation Co., Ltd. KRL & Four Ball Test Machine
Ball: Steel Balls for Four Ball Bearings, Size: 1/2
Speed: 1760rpm
Temperature: 25℃
Test duration: 10 seconds; Starting load: 500N
Load increase interval: 10N

As is clear from the results in Tables 2-3, the lubricating oil compositions containing the wear inhibitor of the present invention (Examples 28-54) exhibit high wear prevention, low copper corrosion, high volume resistivity, and excellent insulating properties. On the other hand, the lubricating oil compositions of Comparative Examples 5-8 are significantly inferior to the lubricating oil compositions containing the wear inhibitor of the present invention in at least one of the following properties: wear prevention, copper corrosion, and insulating properties.

The lubricating oil composition containing the wear inhibitor of the present invention is suitable as a drivetrain lubricant (MTF, differential gear oil, ATF, and belt-CVTF, etc.), hydraulic fluid (machine hydraulic fluid, power steering fluid, and shock absorber oil, etc.), engine oil (for gasoline and diesel engines, etc.), traction oil, and motor oil in electric vehicles or hybrid vehicles.

Claims (6)

An anti-wear agent comprising a copolymer (A) having monomer (a) represented by the following general formula (1), monomer (b) represented by the following general formula (2), and monomer (c) represented by the following general formula (3) as essential constituent monomers, wherein the weight ratio (a/b) of monomer (a) to monomer (b) in the monomers constituting the copolymer (A) is 0.5 to 80, and the acid value of the copolymer (A) is 1.0 to 38 mgKOH/g .
[In general formula (1), A is a polymerizable unsaturated group having 2 to 5 carbon atoms; ^-X1- , ^-X2- , and ^-X3- are each independently represented by a group -O-; ^R1 is an alkylene group having 1 to 4 carbon atoms; ^R2 is an alkylene group having 2 to 20 carbon atoms; ^R3 is a hydrogen atom or a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms; p is an integer from 1 to 100, and if p is 2 or greater, the multiple ^R2 and ^X3 may be the same or different.]
[In general formula (2), R ⁴ is a hydrogen atom or a methyl group; -X ^4- is a group represented by -O-; and R ⁵ represents an alkylene group having 1 to 10 carbon atoms. q is an integer from 1 to 100, and when q is 2 or greater, R ⁵ may be the same or different.]
[In general formula (3), R ⁶ is a hydrogen atom or a methyl group; -X ^5- is a group represented by -O-; and R ⁷ is a linear or branched alkyl group having 5 to 44 carbon atoms.] The anti-wear agent according to claim 1, wherein the total weight ratio of monomer (a) and monomer (b) in the monomers constituting the copolymer (A) is 15 to 50% by weight, based on the total weight of the constituent monomers of (A). The wear inhibitor according to claim 1, wherein the weight-average molecular weight of the copolymer (A) is 0.5 million to 500,000. A lubricating oil composition comprising an anti-wear agent and a base oil according to any one of claims 1 to 3 . The lubricating oil composition according to claim 4 , wherein the kinematic viscosity of the base oil at 100°C is 1 to 4 ^mm² /s. The lubricating oil composition according to claim 4, further comprising at least one selected from the group consisting of viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, extreme pressure agents, defoamers, anti-emulsifiers, corrosion inhibitors, and pour point depressants.