Wear inhibitor and lubricating oil composition

Abstract

The purpose of the present invention is to provide: a wear inhibitor which is not likely to gel at high temperatures and is not likely to precipitate in a lubricating oil composition; and a lubricating oil composition which contains this wear inhibitor. Provided is a wear inhibitor which contains a copolymer (A) that has, as essential constituent monomers, a monomer (a) represented by general formula (1) and a monomer (b) represented by general formula (2) or (2'). With respect to the monomer (a) among the monomers that constitute the copolymer (A), the average value of p per mole of the monomer (a) is 1-4.

Description

Antiwear agent and lubricating oil composition

[0001] The present invention relates to antiwear agents and lubricating oil compositions.

[0002] In order to improve fuel economy in recent years, there has been a demand for improved power transmission efficiency and smaller, lighter automobile transmissions, and the transmission mechanisms have shifted from manual transmissions to automatic transmissions, and more recently, continuously variable transmissions have been 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 using these batteries in combination with internal combustion engines, have been developed, and these vehicles have traditionally used transmission oil and electric motor oil separately.

[0003] Recently, in the field of electric vehicles or hybrid vehicles, there has been a demand for standardization of oils and for packaging of transmissions and electric motors to reduce size and weight. This has led to a demand for new oils that not only have the anti-wear properties of manual transmission oils, automatic transmission oils, or continuously variable transmission oils, but also the insulating properties of electric motor oils.

[0004] Anti-wear agents are used to meet requirements for anti-wear properties, anti-seizure properties, etc., and typically, phosphate esters, zinc dithiophosphates, organic sulfur compounds, etc. are added to mineral oil or synthetic base oils. However, transmission oils containing these anti-wear agents have insufficient insulating properties, and when used as electric motor oils, they can cause problems such as short circuits in electric motors. Therefore, electric vehicles and hybrid vehicles require anti-wear agents that can provide both insulating properties and anti-wear properties.

[0005] Examples of anti-wear agents that do not deteriorate insulation properties include polymeric anti-wear agents that do not contain sulfur or phosphorus as constituent elements, and specific examples include copolymers consisting of α-olefins and fumaric acid esters (Patent Document 1), acrylic acid ester copolymers having hydroxy 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). However, the above-mentioned polymeric anti-wear agents have the problem that their anti-wear effect is insufficient.

[0006] In addition, (meth)acrylic acid ester copolymers containing monomers of specific structures as essential constituent monomers are known as friction modifiers (Patent Documents 5, 6, 7, and 8). However, although the above friction modifiers have a high friction-reducing effect, their anti-wear effect has been unclear. Furthermore, the (meth)acrylic acid ester copolymers having constituent monomers with carboxy groups described in Patent Documents 7 and 8 have the problem of gelling at high temperatures when used as anti-wear agents containing the (meth)acrylic acid ester copolymers at high concentrations. In addition, when a lubricating oil composition containing an anti-wear agent is produced and stored for a long period of time, there is a problem of polymer precipitation.

[0007] Japanese Patent No. 3730660 Japanese Patent No. 5822706 Japanese Patent No. 5684832 Japanese Patent No. 4686444 Japanese Patent No. 2022-151618 Japanese Patent No. 6582021 Japanese Patent No. 2020-139146 Japanese Patent No. 2020-139145

[0008] An object of the present invention is to provide an antiwear agent which is resistant to gelling at high temperatures and resistant to precipitation in a lubricating oil composition, and a lubricating oil composition containing the same.

[0009] As a result of extensive investigations, the present inventors have arrived at the present invention. Specifically, the present invention relates to an antiwear agent containing a copolymer (A) having, as essential constituent monomers, a monomer (a) represented by the following general formula (1) and a monomer (b) represented by the following general formula (2) or (2'), wherein, in the monomers constituting the copolymer (A), the average value of p per mole of monomer (a) is 1 to 4; and a lubricating oil composition containing the antiwear agent and a base oil. [In general formula (1), A １ represents a polymerizable unsaturated group having 2 to 5 carbon atoms; -X １ -, -X ２ - and -X ３ - each independently represents a group represented by -O- or -NH-; R １ is an alkylene group having 1 to 4 carbon atoms; R ２ is an alkylene group having 2 to 20 carbon atoms; p is an integer of 1 to 100, and when p is 2 or more, a plurality of R ２ and X ３ may be the same or different; R ３ represents a hydrogen atom, a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, a phenyl group in which a 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 a hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms.] [In the general formulas (2) and (2′), A ２ represents a polymerizable unsaturated group having 2 to 5 carbon atoms; -X ４ - is a group represented by -O- or -NH-; -Y １ - represents a divalent hydrocarbon group having 2 to 400 carbon atoms, some of the bonds of which may be substituted with at least one bond selected from the group consisting of -O-, -NH-, -C(=O)O-, -OC(=O)-, -C(=O)NH-, and -NHC(=O)-; Z １represents a residue obtained by removing one carboxy group (X1) from a polycarboxylic acid (Z1), and the polycarboxylic acid (Z1) is a compound in which a hydrogen atom is not bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X2) other than the (X1); Z ２ represents a residue obtained by removing one hydroxy group from a hydroxy(poly)carboxylic acid (Z2), and the hydroxy(poly)carboxylic acid (Z2) is a compound in which no hydrogen atom is bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X3) of (Z2).]

[0010] According to the present invention, it is possible to provide an antiwear agent that is resistant to gelling at high temperatures and resistant to deposition in a lubricating oil composition, and a lubricating oil composition containing the same.

[0011] <Anti-wear agent> The anti-wear agent of the present invention contains a copolymer (A) having, as essential constituent monomers, a monomer (a) represented by the general formula (1) described below and a monomer (b) represented by the general formula (2) or (2′).

[0012] In the present invention, the copolymer (A) contains a monomer (a) represented by the following general formula (1) as a constituent monomer. ２ -X ３ ) ｐ The moiety is highly polar and contributes to the ability to adsorb to metals, and therefore, when the copolymer (A) contains the monomer (a) as a constituent monomer, the anti-wear properties can be improved. [In general formula (1), A １ represents a polymerizable unsaturated group having 2 to 5 carbon atoms; -X １ -, -X ２ - and -X ３ - each independently represents a group represented by -O- or -NH-; R １ is an alkylene group having 1 to 4 carbon atoms; R ２ is an alkylene group having 2 to 20 carbon atoms; p is an integer of 1 to 100, and when p is 2 or more, a plurality of R ２ and X ３ may be the same or different; R ３represents a hydrogen atom, a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, a phenyl group in which a 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 a hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms.]

[0013] In general formula (1), A １ is a polymerizable unsaturated group having 2 to 5 carbon atoms (hereinafter sometimes abbreviated as C). The polymerizable unsaturated group means a functional group having a carbon-carbon double bond capable of undergoing an addition polymerization reaction, and specific examples thereof include a radically polymerizable unsaturated group and a cationically polymerizable unsaturated group. Examples of the polymerizable unsaturated group include a C2 to C5 alkenyl group {e.g., a vinyl group, an allyl group, a homoallyl group (3-butenyl group), a 2-butenyl group, a methallyl group (2-methyl-1-propenyl group), a 3-methyl-3-butenyl group, a 3-methyl-2-butenyl group, a 2-methyl-3-butenyl group, a 2-methyl-2-butenyl group, and a 1,1-dimethyl-2-propenyl group}, a (meth)acryloyl group {H ２ C=C(H or CH ３ )-C(=O)-}. １ From the viewpoints of reactivity and anti-wear properties, vinyl groups and (meth)acryloyl groups are preferred, and (meth)acryloyl groups are more preferred. In the present invention, "(meth)acryloyl" means "acryloyl and / or methacryloyl", and "(meth)acrylate" means "acrylate and / or methacrylate".

[0014] In the general formula (1), -X １ -, -X ２ - and -X ３ Each - is independently a group represented by -O- or -NH-. １ -, -X ２ - and -X ３ From the viewpoint of wear prevention, the - is preferably -O-.

[0015] In general formula (1), R １is an alkylene group having 1 to 4 carbon atoms. Examples of the alkylene group having 1 to 4 carbon atoms include a methylene group, an ethylene group, a 1,2- or 1,3-propylene group, and a 1,2-, 1,3-, or 1,4-butylene group. Of these, from the viewpoint of anti-wear properties, an ethylene group and a 1,2- or 1,3-propylene group are preferred, and an ethylene group is more preferred.

[0016] In general formula (1), R ２ represents an alkylene group having 2 to 20 carbon atoms, and specific examples thereof include an ethylene group, an isopropylene group, a 1,2- or 1,3-propylene group, an isobutylene group, a 1,2-, 1,3-, or 1,4-butylene group, an isopentylene group, a 1,2-, 1,3-, 1,4-, or 1,5-pentylene group, an isohexylene group, a 1,2-, 1,3-, 1,4-, 1,5-, or 1,6-hexylene group, an isoheptylene group, a 1,2-, 1,3-, 1,4-, 1,5-, 1,6-, or 1,7-heptylene group, an isooctylene group, a 1,8-octylene group, an isononylene group, a 1,9-nonylene group, an isodecylene group, a 1,1 Examples of the alkyl group include an 0-decylene group, an isoundecylene group, a 1,11-undecylene group, an isododecylene group, a 1,12-dodecylene group, an isotridecylene group, a 1,13-tridecylene group, an isotetradecylene group, a 1,14-tetradecylene group, an isopentadecylene group, a 1,15-pentadecylene group, an isohexadecylene group, a 1,16-hexadecylene group, an isoheptadecylene group, a 1,17-heptadecylene group, an isooctadecylene group, a 1,18-isooctadecylene group, an isononadecylene group, a 1,19-isononadecylene group, an isoeicosylene group, and a 1,20-eicosylene group. ２ From the viewpoint of wear prevention, the alkylene group is preferably a C2-17 alkylene group, more preferably a C2-15 alkylene group, particularly preferably a C2-13 alkylene group, and most preferably a C2-10 alkylene group.

[0017] In the general formula (1), p represents the number of (CO-R ２ -X ３ ) groups (e.g., groups derived from lactams and / or lactones) and is an integer of 1 to 100. When p is 2 or more, a plurality of R ２ and X３ may be the same or different. In the monomer (a) among the monomers constituting copolymer (A), the average value of p (average number of added moles, hereinafter also referred to as the molar average value of p) per mole of monomer (a) is 1 to 4, preferably 1.5 to 3.5, and more preferably 2.0 to 3.5, from the viewpoint of anti-wear properties and making the anti-wear agent less likely to precipitate (long-term stability). If the average value of p per mole of monomer (a) exceeds 4, anti-wear properties and long-term stability may deteriorate. The reason for the deterioration of the long-term stability of the anti-wear agent is unclear, but it is presumed that when the molar average value of p exceeds 4, the number of ester groups and / or amide groups in copolymer (A) increases, making it easier for molecules to aggregate together even at room temperature. Furthermore, reducing the proportion of monomer (a) in the constituent monomers of copolymer (A) to avoid precipitation reduces anti-wear properties. When the copolymer (A) is composed of two or more types of monomers (a), the molar average value of p in the general formula (1) is determined by weighting the p of each monomer (a) based on the molar fraction of each monomer in the monomer (a). １ The molar average value of p can be measured from the H-NMR (nuclear magnetic resonance) spectrum. １ is a (meth)acryloyl group, and (CO-R ２ -X ３ When the γ-hydrogen of the carbonyl carbon derived from ε-caprolactone is a -CO-CH group, the molar average value of p can be calculated by dividing half of the integral of the peak near 1.4 ppm (the peak of γ-hydrogen of the carbonyl carbon derived from ε-caprolactone) by the integral of the peak near 6.4 ppm or 6.1 ppm (the peak of one of the hydrogen atoms bonded to the unsaturated double bond of the acryloyl group or methacryloyl group). ２ -CH ２ -C ＊ H ２ -CH ２ -CH ２The hydrogen atom bonded to the carbon atom marked with * in —O— is the hydrogen atom bonded to the unsaturated double bond of the acryloyl group. ２ C ＊ In =CH-CO-, the hydrogen atom bonded to the carbon atom marked with * is the hydrogen atom bonded to the unsaturated double bond of the methacryloyl group. ２ C ＊ =C(CH ３ )-CO- means a hydrogen atom bonded to the carbon atom marked with *. Specifically, the molar average value of p can be calculated by the following formula. １ is an acryloyl group) Molar average value of p=(integral value of the peak of γ hydrogen of the carbonyl carbon derived from ε-caprolactone / 2) / (integral value of one peak of the hydrogen atoms bonded to the unsaturated double bond of the acryloyl group) １ is a methacryloyl group), molar average value of p=(integral value of the peak of γ hydrogen of the carbonyl carbon derived from ε-caprolactone / 2) / (integral value of one peak of the hydrogen atoms bonded to the unsaturated double bond of the methacryloyl group)

[0018] R in general formula (1) ３ is a hydrogen atom, a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, a phenyl group in which a 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 a hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms.

[0019] Specific examples of the linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms include saturated chain aliphatic hydrocarbon 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-tridecanyl group, decyl group, isotridecyl group, n-tetradecyl group, 2-ethyldodecyl group, n-pentadecyl group, 2-methyltetradecyl group, n-hexadecyl group, isohexadecyl group, n-heptadecyl group, isoheptadecyl group, 2-ethylpentadecyl group, 2-octylnonyl group, 2-(3-methylhexyl)-7-methyl-nonyl group, n-octadecyl group, isooctadecyl group, 2-hexylundecyl group decyl 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-tetracosyl group, 2-decyltetradecyl group, 2-dodecylpentadecyl group, 2-heptylicosyl group, 2-dodecylhexadecyl group, n-triacontyl group, 2-tetracosyl group, a 2-ethyltetracontyl group, an n-tetradecyl group, an n-octadecyl group, an n-hexatriacontyl group, an n-tetracontyl group, an n-ethyltetracontyl group, etc.), an unsaturated chain aliphatic hydrocarbon group, and a residue obtained by removing a hydroxyl group from an oxo alcohol obtained from an olefin [for example, a propylene oligomer (dimer to tetratetramer), an ethylene / propylene oligomer (dimer to 20mer), an isobutene oligomer (dimer to 10mer), etc.].

[0020] Examples of phenyl groups in which a hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms include phenyl, o-, m-, or p-methylphenyl, and o-, m-, or p-ethylphenyl. Examples of acyl groups having a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms include acetyl, propionyl, butyryl, isobutyryl, valeryl, isovaleryl, and pivaloyl. Examples of benzoyl groups in which a hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms include benzoyl and toluoyl groups.

[0021] These R ３ Among these, from the viewpoint of anti-wear properties, preferred are a hydrogen atom, a C1-12 alkyl group, an acyl group having a C1-12 linear or branched alkyl group, a phenyl group optionally substituted with a C1-12 linear or branched alkyl group, or a benzoyl group optionally substituted with a C1-12 linear or branched alkyl group, and more preferred is a hydrogen atom.

[0022] From the viewpoint of anti-wear properties, preferred examples of the monomer (a) include (a1) an adduct of 1 to 4 moles of lactone with a hydroxyalkyl(meth)acryloyl monomer, (a2) an adduct of 1 to 4 moles of lactam with a hydroxyalkyl(meth)acryloyl monomer, (a3) ​​an adduct of 1 to 4 moles of lactone with an aminoalkyl(meth)acryloyl monomer, (a4) an adduct of 1 to 4 moles of lactam with an aminoalkyl(meth)acryloyl monomer, (a5) an esterified product or (a6) an amidated product of the adduct (a1) to (a4) with a monocarboxylic acid (for example, a C2 to 45 monocarboxylic acid), and (a7) an etherified product which is a reaction product of the adduct (a1) or (a3) ​​with a C1 to 44 alkylating agent or aromatic halide, and more preferred is (a1) an adduct of 1 to 4 moles of lactone with a hydroxyalkyl(meth)acryloyl monomer.

[0023] Examples of the hydroxyalkyl(meth)acryloyl monomer 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.}.

[0024] Examples of the aminoalkyl(meth)acryloyl monomer 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.}.

[0025] Lactones include those having 3 to 21 carbon atoms, such as β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone.

[0026] Lactams include those having C3 to C21, such as β-lactam, γ-lactam, and δ-lactam.

[0027] Examples of monocarboxylic acids include C2 to C45 aliphatic monocarboxylic acids {e.g., linear saturated aliphatic monocarboxylic acids (e.g., ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, etc.), 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, benzoic acid in which some of the hydrogen atoms bonded to the aromatic ring are substituted with C1 to C44 linear aliphatic hydrocarbon groups (e.g., 4-alkylbenzoic acid (alkyl group having 1 to 44 carbon atoms), etc.)}.

[0028] Examples of C1-44 alkylating agents include alkyl chlorides such as methyl chloride, ethyl chloride, propyl chloride, butyl chloride, and isopropyl chloride; alkyl bromides such as methyl bromide, ethyl bromide, propyl bromide, butyl bromide, and isopropyl bromide; etc. Examples of aromatic halides include halogenated aromatic compounds such as fluorinated and chlorinated compounds, and examples thereof include halogenated benzenes and halogenated alkylbenzenes having a C1-44 chain aliphatic hydrocarbon group (e.g., 1-halogenated-4-alkyl (alkyl group having 1 to 44 carbon atoms) benzenes).

[0029] From the viewpoint of anti-wear properties, preferred examples of the monomer (a) include: an adduct of 1 to 4 moles of a lactone to a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms) (meth)acrylate; an alkyl (alkyl group having 1 to 12 carbon atoms) adduct of 1 to 4 moles of a lactone to a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms) (meth)acrylate; a reaction product of an adduct of 1 to 4 moles of a lactone to a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms) (meth)acrylate with an aromatic halide (which may have a C1 to 12 alkyl group); an esterification product of an adduct of 1 to 4 moles of a lactone to a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms) (meth)acrylate with a C2 to 13 chain aliphatic monocarboxylic acid; and an esterification product of an adduct of 1 to 4 moles of a lactone to a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms) (meth)acrylate with an aromatic monocarboxylic acid (which may have a C1 to 12 alkyl group). More preferred are adducts of hydroxyalkyl (hydroxyalkyl group having 2 to 3 carbon atoms) (meth)acrylate with 1 to 4 moles of ε-caprolactone, alkyl (alkyl group having 1 to 12 carbon atoms) adducts of hydroxyalkyl (hydroxyalkyl group having 2 to 3 carbon atoms) (meth)acrylate with 1 to 4 moles of ε-caprolactone, reaction products of adducts of hydroxyalkyl (hydroxyalkyl group having 2 to 3 carbon atoms) (meth)acrylate with halides of aromatic (which may have a C1 to 12 alkyl group), esters of adducts of hydroxyalkyl (hydroxyalkyl group having 2 to 3 carbon atoms) (meth)acrylate with 1 to 4 moles of ε-caprolactone and linear C2 to C13 aliphatic monocarboxylic acids, and esters of adducts of hydroxyalkyl (hydroxyalkyl group having 2 to 3 carbon atoms) (meth)acrylate with 1 to 4 moles of ε-caprolactone and aromatic monocarboxylic (which may have a C1 to 12 alkyl group).Particularly preferred are an adduct of 1 to 4 moles of ε-caprolactone to hydroxyethyl (meth)acrylate, an alkylated product (the alkyl group has 1 to 12 carbon atoms) of an adduct of 1 to 4 moles of ε-caprolactone to hydroxyethyl (meth)acrylate, a reaction product of an adduct of 1 to 4 moles of ε-caprolactone to hydroxyethyl (meth)acrylate with an aromatic halide (which may have a C1 to 12 alkyl group), an esterified product of an adduct of 1 to 4 moles of ε-caprolactone to hydroxyethyl (meth)acrylate with a C2 to 13 chain aliphatic monocarboxylic acid, and an esterified product of an adduct of 1 to 4 moles of ε-caprolactone to hydroxyethyl (meth)acrylate with an aromatic monocarboxylic acid (which may have a C1 to 12 alkyl group). Most preferred is an adduct of 1 to 4 moles of ε-caprolactone to hydroxyethyl (meth)acrylate.

[0030] The 1 to 4 mole lactone adduct of a hydroxyalkyl(meth)acryloyl monomer or an aminoalkyl(meth)acryloyl monomer can be obtained, for example, by ring-opening addition of a lactone to a hydroxyalkyl(meth)acryloyl monomer or an aminoalkyl(meth)acryloyl monomer. The reaction temperature during the ring-opening addition reaction is preferably 80 to 150°C, more preferably 100 to 140°C, from the viewpoint of reaction time. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours. The reaction may be carried out in the presence of a catalyst. The catalyst for the above reaction may be a known catalyst, such as p-toluenesulfonic acid, tetrapropyl titanate, or stannous octoate. The amount of catalyst used is preferably 0.01 to 5 wt %, more preferably 0.03 to 0.5 wt %, based on the amount of the reaction product. After the ring-opening addition reaction is completed, the catalyst is desirably treated by a method such as adsorption using an adsorbent, filtration and removal, or neutralization to inactivate the catalyst.

[0031] A 1-4 mole lactam adduct of a hydroxyalkyl(meth)acryloyl monomer or an aminoalkyl(meth)acryloyl monomer can be obtained, for example, by ring-opening addition of a lactam to a hydroxyalkyl(meth)acryloyl monomer or an aminoalkyl(meth)acryloyl monomer. The reaction temperature during the ring-opening addition reaction of a lactam is preferably 80 to 150°C, more preferably 100 to 140°C, from the viewpoint of reaction time. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours. The reaction may be carried out in the presence of a catalyst. The catalyst for the above reaction may be a known catalyst, such as tetrapropyl titanate or stannous octoate. The amount of catalyst used is preferably 0.01 to 5 wt%, more preferably 0.03 to 0.5 wt%, based on the amount of the reaction product. After completion of the ring-opening addition reaction, the catalyst is desirably treated by, for example, adsorbing and filtering with an adsorbent to remove the lactam, or neutralizing the catalyst to inactivate it.

[0032] The reaction temperature when the adducts (a1) to (a4) are esterified with a monocarboxylic acid is preferably 80°C to 150°C, more preferably 90°C to 130°C, from the viewpoints of reaction time and prevention of polymerization of (meth)acrylic acid. The reaction pressure during the esterification reaction may be reduced in order to remove the water produced. From the viewpoints of reaction time and prevention of polymerization, the reaction pressure is preferably 0.007 to 0.095 MPa, more preferably 0.01 to 0.092 MPa. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours. The esterification reaction is desirably carried out in the presence of a catalyst. The catalyst for the esterification reaction may be a known catalyst, such as sulfuric acid or p-toluenesulfonic acid. A solvent may also be used in the esterification reaction. Examples of the solvent include water-insoluble solvents with a boiling point of 150°C or less, such as cyclohexane and toluene.

[0033] The reaction temperature when the adducts (a1) to (a4) are subjected to the amidation reaction with the monocarboxylic acid is preferably 80°C to 150°C, more preferably 90°C to 130°C, from the viewpoints of reaction time and prevention of polymerization of (meth)acrylic acid. Furthermore, the reaction pressure during the amidation reaction may be reduced in order to remove the water produced. From the viewpoints of reaction time and prevention of polymerization, the preferred reaction pressure is preferably 0.007 to 0.095 MPa, more preferably 0.01 to 0.092 MPa. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours.

[0034] The reaction of the adduct (a1) or (a3) ​​with a C1-44 alkylating agent can be carried out under general conditions in the presence of a base (e.g., an amine, a quaternary ammonium salt, sodium hydroxide, etc.).

[0035] The structural unit derived from the monomer (a) (a structure in which the polymerizable unsaturated group of the monomer (a) is reacted to form a single bond) has a specific solubility parameter (hereinafter sometimes abbreviated as SP value) in terms of solubility in the lubricating base oil. ３ ) １／２ The SP value of the structural unit derived from the monomer (a) is preferably 9.0 to 12.5 (cal / cm ３ ) １／２ and more preferably 9.3 to 12.3 (cal / cm ３ ) １／２ and particularly preferably 9.5 to 12.0 (cal / cm ３ ) １／２ The SP value in the present invention refers to a value calculated by the Fedors method, that is, a value calculated by the formula (28) described on page 153 of Polymer Engineering and Science, February 1974, Vol. 14, No. 2, pp. 147-154, page 152 (Table 5) using the values ​​(heat of vaporization and molar volume at 25°C of atoms or functional groups). Specifically, the Δe ｉ and Δv ｉThe SP value can be calculated by applying the values ​​corresponding to the types of atoms and atomic groups in the molecular structure to the following formula: SP value = (ΣΔe ｉ / ΣΔv ｉ ) １／２ [In the formula, ΣΔe ｉ (unit: cal / mol) is the cohesive energy density (unit: cal / mol), and ΣΔv ｉ is the molecular volume (unit: cm ３ / mol).

[0036]

[0037]

[0038] When two or more types of monomers (a) are used in combination as constituent monomers, it is preferable that the SP values ​​of the constituent units derived from each monomer (a) are calculated by the above-mentioned method, and the weighted average based on the weight fraction of each monomer (a) falls within the above-mentioned range.

[0039] From the viewpoint of anti-wear properties, the molecular formula weight or number average molecular weight (hereinafter abbreviated as Mn) of the monomer (a) is preferably 150 to 600, more preferably 150 to 530, and particularly preferably 150 to 480. The Mn of the monomer (a) and the weight average molecular weight (hereinafter abbreviated as Mw) of the copolymer (A) described later can be measured by gel permeation chromatography (hereinafter abbreviated as GPC) under the following conditions. <Conditions for measuring Mn of monomer (a) and Mw of copolymer (A)> Apparatus: "HLC-8320GPC" [manufactured by Tosoh Corporation] Column: "TSKgel guard column Super HZ-L" [manufactured by Tosoh Corporation] 1 column, "TSKgel Super HZM-M" [manufactured by Tosoh Corporation] 3 columns Measurement temperature: 40°C Sample solution: 0.25 wt% tetrahydrofuran solution Solution injection amount: 10 μl Detector: RI (differential refractometer) Reference material: standard polystyrene (TSKgel standard POLYSTYRENE) 11 types (molecular weights: 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]

[0040] In the present invention, the copolymer (A) contains a monomer (b) represented by the following general formula (2) or (2') as a constituent monomer. [In the general formulas (2) and (2′), A ２ represents a polymerizable unsaturated group having 2 to 5 carbon atoms; -X ４ - is a group represented by -O- or -NH-; -Y １ - represents a divalent hydrocarbon group having 2 to 400 carbon atoms, some of the bonds of which may be substituted with at least one bond selected from the group consisting of -O-, -NH-, -C(=O)O-, -OC(=O)-, -C(=O)NH-, and -NHC(=O)-; Z １ represents a residue obtained by removing one carboxy group (X1) from a polycarboxylic acid (Z1), and the polycarboxylic acid (Z1) is a compound in which a hydrogen atom is not bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X2) other than the (X1); Z ２ represents a residue obtained by removing one hydroxy group from a hydroxy(poly)carboxylic acid (Z2), and the hydroxy(poly)carboxylic acid (Z2) is a compound in which a hydrogen atom is not bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X3) of (Z2).] When the copolymer (A) contains the monomer (b) as a constituent monomer, the carboxy group of the monomer (b) [the carboxy group (X2) derived from the polycarboxylic acid (Z1) and / or the carboxy group (X3) derived from the hydroxy(poly)carboxylic acid (Z2)] enhances the adsorptivity to metals, and therefore, the (CO-R ２ -X ３ ) ｐ This allows the portion to easily approach the metal surface, improving the anti-wear properties. Furthermore, since no hydrogen atom is bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X2) and / or (X3) in the monomer (b), it is presumed that crosslinking reaction of the copolymer (A) is unlikely to occur and the anti-wear agent is unlikely to gel. This is because the hydrogen atom bonded to the carbon atom at the α-position relative to the carbonyl group (referred to as α-hydrogen) is easily abstracted, and this abstraction makes the crosslinking reaction more likely to occur. Furthermore, the monomer (b) does not contain -Y １By having -, -Y of (meth)acrylic acid or the like can be obtained. １ It is presumed that, compared with a monomer not having -, the carboxy groups (X2) and / or (X3) of the monomer (b) are less likely to be buried in the side chain derived from the monomer (a), thereby enhancing the adsorption power to metals. In the present invention, the (poly)carboxylic acid means "monocarboxylic acid and / or polycarboxylic acid".

[0041] In the general formulas (2) and (2′), A ２ is a polymerizable unsaturated group having 2 to 5 carbon atoms, and examples thereof include A in the general formula (1). １ It is the same as above. ２ From the viewpoints of reactivity and anti-wear properties, vinyl groups and (meth)acryloyl groups are preferred, and (meth)acryloyl groups are more preferred.

[0042] In the general formulas (2) and (2′), —X ４ - is a group represented by -O- or -NH-, and is preferably -O- from the viewpoint of anti-wear properties.

[0043] In the general formulas (2) and (2′), —Y １ - represents a divalent hydrocarbon group having 2 to 400 carbon atoms, some of the bonds of which may be substituted with at least one bond selected from the group consisting of -O-, -NH-, -C(=O)O-, -OC(=O)-, -C(=O)NH-, and -NHC(=O)-. Examples of the hydrocarbon group include a chain aliphatic group, an aliphatic group containing an alicyclic skeleton, and an aromatic group-containing hydrocarbon group. From the viewpoint of wear prevention and long-term stability, -Y １ The number of carbon atoms in - (excluding the carbon of the carbonyl group) is preferably 5 to 30, and more preferably 5 to 22. １Of the bonds in the hydrocarbon group, the total number of bonds substituted with -O-, -NH-, -C(=O)O-, -OC(=O)-, -C(=O)NH-, or -NHC(=O)- is preferably 6 or less, more preferably 1 to 4, from the viewpoint of long-term stability and anti-wear properties. The fewer the number of substituted bonds, the better the long-term stability tends to be, even when a large amount of monomer (b) is used, and the more the number of substituted bonds, the better the anti-wear properties tend to be. １ From the viewpoints of long-term stability and anti-wear properties, the total number of bonds substituted with -C(=O)O-, -OC(=O)-, -C(=O)NH-, or -NHC(=O)- among the bonds in the hydrocarbon group is preferably 6 or less, more preferably 4 or less, and even more preferably 1 to 3. The fewer the number of substituted bonds, the better the long-term stability tends to be, even when a large amount of monomer (b) is used, and the greater the number of substituted bonds, the better the anti-wear properties tend to be.

[0044] In the general formulas (2) and (2′), —Y １ From the viewpoint of anti-wear properties, - is preferably an alkylene group having 2 to 20 carbon atoms or a group represented by the following general formula (3), (4), or (5): ４ O) ｑ -R ５ - (3) [In general formula (3), R ４ O is an alkyleneoxy group having 2 to 4 carbon atoms, q is an integer from 1 to 20, and when q is 2 or more, there are a plurality of R ４ may be the same or different; R ５ is an alkylene group having 2 to 4 carbon atoms. ６ -(X ５ -C(=O)-R ７ ) ｒ - (4) [In general formula (4), R ６ represents an alkylene group having 1 to 4 carbon atoms; X ５ represents a group represented by —O— or —NH—, R ７ represents an alkylene group having 2 to 20 carbon atoms, r is an integer of 1 to 20, and when r is 2 or more, there are a plurality of R ７ and X５ may be the same or different.] -(R ８ -C(=O)-X ６ ) ｓ -R ９ - (5) [In general formula (5), R ８ represents an alkylene group having 2 to 20 carbon atoms, and -X ６ - represents a group represented by -O- or -NH-, s is an integer of 1 to 20, and when s is 2 or more, there are a plurality of R ８ and X ６ may be the same or different, R ９ is an alkylene group having 2 to 20 carbon atoms.] The monomer (b) is a compound represented by general formula (2), and -Y １ It is more preferable that - is a group represented by formula (4).

[0045] -Y in formulas (2) and (2') １ In a preferred embodiment of the above, the alkylene group having 2 to 20 carbon atoms is R ２ Examples of the alkylene group having 2 to 20 carbon atoms include those exemplified in 1. From the viewpoint of anti-wear properties, the alkylene group having 2 to 20 carbon atoms 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.

[0046] In general formula (3), R ４ O represents an alkyleneoxy group having 2 to 4 carbon atoms, such as an ethyleneoxy group, a propyleneoxy group, a butyleneoxy group, etc. Of these, from the viewpoint of anti-wear properties, an ethyleneoxy group and a propyleneoxy group are preferred, and an ethyleneoxy group is more preferred.

[0047] In general formula (3), q represents the number of moles of alkyleneoxy groups added and is an integer of 1 to 20, and from the viewpoint of anti-wear properties, it is preferably 2 to 10, more preferably 2 to 5. Furthermore, in the monomer (b) among the monomers constituting copolymer (A), the average value of q per mole of the monomer represented by general formula (3) is preferably 2 to 10, more preferably 2 to 5, from the viewpoint of anti-wear properties. When q is 2 or more, a plurality of R ４ may be the same or different.

[0048] In general formula (3), R ５ represents an alkylene group having 2 to 4 carbon atoms, such as an ethylene group, a propylene group, a butylene group, etc. Of these, from the viewpoint of anti-wear properties, an ethylene group and a propylene group are preferred, and an ethylene group is more preferred.

[0049] In general formula (4), R ６ represents an alkylene group having 1 to 4 carbon atoms. The alkylene group having 1 to 4 carbon atoms is R １ Examples include the same as those exemplified in R. ６ From the viewpoint of anti-wear properties, the alkyl group is preferably an ethylene group or a 1,2- or 1,3-propylene group, and more preferably an ethylene group.

[0050] In general formula (4), X ５ represents a group represented by —O— or —NH—, and is preferably —O— from the viewpoint of anti-wear properties.

[0051] In general formula (4), R ７ represents an alkylene group having 2 to 20 carbon atoms. The alkylene group having 2 to 20 carbon atoms is R ２ Examples include the same as those exemplified in R. ７ From the viewpoint of wear prevention, the alkylene group is preferably a C2-17 alkylene group, more preferably a C2-15 alkylene group, particularly preferably a C2-13 alkylene group, and most preferably a C2-10 alkylene group.

[0052] In the general formula (4), r is the (X ５-C(=O)-R ７ ) group (for example, a group derived from lactone or lactam), and is an integer of 1 to 20. From the viewpoints of long-term stability and anti-wear properties, it is preferably 1 to 5, more preferably 1 to 4, and even more preferably 2 to 3. In addition, in the monomer (b) among the monomers constituting the copolymer (A), the average value of r per mole of the monomer (b) (also referred to as the molar average value of r) is preferably 1 to 5, more preferably 1 to 4, and even more preferably 2 to 3, from the viewpoints of long-term stability and anti-wear properties. When r is 2 or more, a plurality of R ７ and X ５ may be the same or different.

[0053] In general formula (5), R ８ represents an alkylene group having 2 to 20 carbon atoms. The alkylene group having 2 to 20 carbon atoms is R ２ Examples include the same as those exemplified in R. ８ From the viewpoint of wear prevention, the alkylene group is preferably a C2-17 alkylene group, more preferably a C2-15 alkylene group, particularly preferably a C2-13 alkylene group, and most preferably a C2-10 alkylene group.

[0054] In the general formula (5), -X ６ "-" represents a group represented by -O- or -NH-, and is preferably -O- from the viewpoint of anti-wear properties.

[0055] In the general formula (5), s is the number of (R ８ -C(=O)-X ６ ) group (for example, a group derived from lactone or lactam), and is an integer of 1 to 20. From the viewpoints of long-term stability and anti-wear properties, it is preferably 1 to 5, more preferably 1 to 4, and even more preferably 2 to 3. In addition, in the monomer (b) among the monomers constituting the copolymer (A), the average value of s per mole of the monomer (b) (the molar average value of s) is preferably 1 to 5, more preferably 1 to 4, and even more preferably 2 to 3, from the viewpoints of long-term stability and anti-wear properties. When s is 2 or more, a plurality of R ８ and X ６ may be the same or different.

[0056] In general formula (5), R ９ represents an alkylene group having 2 to 20 carbon atoms. The alkylene group having 2 to 20 carbon atoms is R ２ Examples include the same as those exemplified in R. ９ From the viewpoint of wear prevention, the alkylene group is preferably a C2-17 alkylene group, more preferably a C2-15 alkylene group, particularly preferably a C2-13 alkylene group, and most preferably a C2-10 alkylene group.

[0057] In the general formula (2), Z １ represents a residue obtained by removing one carboxy group (X1) from a polycarboxylic acid (Z1), and the polycarboxylic acid (Z1) is a compound in which a hydrogen atom is not bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X2) other than the (X1).

[0058] Examples of the polycarboxylic acid (Z1) include those having 5 to 12 carbon atoms, such as aromatic polycarboxylic acids (e.g., phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, benzenepentacarboxylic acid, benzenehexacarboxylic acid (mellitic acid), etc.), aliphatic dicarboxylic acids (e.g., dimethylmalonic acid, 2,2-dimethylsuccinic acid, 2-ethyl-2-methylsuccinic acid, 2,2-dimethylglutaric acid, 2,2-dimethyladipic acid, 2,2-dimethylpimelic acid, etc.), trivalent or higher aliphatic polycarboxylic acids (e.g., methanetetracarboxylic acid, ethane-1,1,1-tricarboxylic acid, propane-1,1,1-tricarboxylic acid, butane-1,1,1-tricarboxylic acid, pentane-1,1,1-tricarboxylic acid, etc.), etc. In addition, when producing the monomer (b), the polycarboxylic acid (Z1) or its anhydride may be used. The polycarboxylic acid (Z1) may be used alone or in combination of two or more. From the viewpoint of long-term stability, the polycarboxylic acid (Z1) is preferably a C5 to C10 polycarboxylic acid, more preferably at least one selected from the group consisting of phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, dimethylmalonic acid, 2,2-dimethylsuccinic acid, 2-ethyl-2-methylsuccinic acid, 2,2-dimethylglutaric acid, and 2,2-dimethyladipic acid, and even more preferably at least one selected from the group consisting of phthalic acid, terephthalic acid, trimellitic acid, dimethylmalonic acid, 2,2-dimethylsuccinic acid, 2-ethyl-2-methylsuccinic acid, and 2,2-dimethylglutaric acid.

[0059] In the general formula (2′), Z ２ represents a residue obtained by removing one hydroxy group from a hydroxy(poly)carboxylic acid (Z2), and the hydroxy(poly)carboxylic acid (Z2) is a compound in which no hydrogen atom is bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X3) of (Z2).

[0060] Examples of the hydroxy(poly)carboxylic acid (Z2) include those having 4 to 8 carbon atoms, such as linear aliphatic hydroxycarboxylic acids (e.g., hydroxypivalic acid, 2-hydroxyisobutyric acid, 2-methylglyceric acid, isomalic acid, 2,2-dimethyl-6-hydroxyhexanoic acid, 2,2-dimethyl-7-hydroxyheptanoic acid, and 2,2-dimethyl-8-hydroxyoctanoic acid), alicyclic group-containing hydroxycarboxylic acids (e.g., 2-hydroxy-1-methylcyclohexane-1-carboxylic acid, 3-hydroxy-1-methylcyclohexane-1-carboxylic acid, 4-hydroxy-1-methylcyclohexane-1-carboxylic acid, 2-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, 3-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, and 4-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid), and aromatic ring-containing hydroxycarboxylic acids (e.g., 2-hydroxymethylbenzoic acid, 3-hydroxymethylbenzoic acid, and 4-hydroxymethylbenzoic acid). In addition, when producing the monomer (b), a hydroxy(polyvalent)carboxylic acid (Z2) or a lactone may be used. Examples of lactones that can generate, upon reaction, a carboxy group in which a hydrogen atom is not bonded to the carbon atom at the α-position relative to the carbonyl group include 3,3-dimethyltetrahydrofuran-2-one, 3,3-diethyltetrahydrofuran-2-one, 3,3-dimethyloxan-2-one, 3,3-diethyloxan-2-one, 3,3-dimethyloxepan-2-one, and 3,3-diethyloxepan-2-one.From the viewpoint of ease of handling, the hydroxy(poly)carboxylic acid (Z2) is preferably a C4-8 hydroxycarboxylic acid, more preferably at least one selected from the group consisting of hydroxypivalic acid, 2-hydroxyisobutyric acid, 2-methylglyceric acid, isomalic acid, 2,2-dimethyl-6-hydroxyhexanoic acid, 3-hydroxy-1-methylcyclohexane-1-carboxylic acid, 4-hydroxy-1-methylcyclohexane-1-carboxylic acid, 3-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, 4-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, 3-hydroxymethylbenzoic acid, and 4-hydroxymethylbenzoic acid, and even more preferably at least one selected from the group consisting of hydroxypivalic acid, 2-hydroxyisobutyric acid, 2-methylglyceric acid, isomalic acid, 4-hydroxy-1-methylcyclohexane-1-carboxylic acid, 4-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, and 4-hydroxymethylbenzoic acid. One type of hydroxy(poly)carboxylic acid (Z2) may be used, or two or more types may be used in combination.

[0061] Examples of the monomer (b) include the following: (i) -Y １- has an alkylene group having 2 to 20 carbon atoms. For example, an esterification product of a hydroxyalkyl (hydroxyalkyl group having 2 to 20 carbon atoms) (meth)acryloyl monomer with a polycarboxylic acid (Z1), an esterification product of a carboxyalkyl (carboxyalkyl group having 3 to 21 carbon atoms) (meth)acryloyl monomer with a hydroxy(poly)carboxylic acid (Z2). Examples of the hydroxyalkyl (hydroxyalkyl group having 2 to 20 carbon atoms) (meth)acryloyl monomer include, in addition to the above-mentioned hydroxyalkyl (meth)acryloyl monomer, hydroxypentyl (meth)acrylate, hydroxypentyl (meth)acrylamide, hydroxyhexyl (meth)acrylate, hydroxyhexyl (meth)acrylamide, hydroxyoctyl (meth)acrylate, hydroxyoctyl (meth)acrylamide, hydroxydecyl (meth)acrylate, hydroxydecyl (meth)acrylamide, hydroxydodecyl (meth)acrylate, hydroxydodecyl (meth)acrylamide, etc. Examples of the carboxyalkyl(meth)acryloyl monomer include 3-((meth)acryloyloxy)propanoic acid, 4-((meth)acryloyloxy)butanoic acid, 5-((meth)acryloyloxy)pentanoic acid, 3-((meth)acryloylamino)propanoic acid, 4-((meth)acryloylamino)butanoic acid, and 5-((meth)acryloylamino)pentanoic acid.

[0062] (ii) -Y １ - has a group of general formula (3) For example, an esterification product of an alkylene oxide (C2-4) adduct (number of moles added: 1-19) of a hydroxyalkyl (hydroxyalkyl group having 2-4 carbon atoms) (meth)acryloyl monomer with the polycarboxylic acid (Z1). Examples of the hydroxyalkyl (hydroxyalkyl group having 2-4 carbon atoms) (meth)acryloyl monomer include the above-mentioned hydroxyalkyl (meth)acryloyl monomers in which the hydroxyalkyl group has 2-4 carbon atoms. Examples of the alkylene oxide having 2-4 carbon atoms include ethylene oxide, 1,2- or 1,3-propylene oxide, 1,2-, 1,3-, 1,4- or 2,3-butylene oxide, etc.

[0063] (iii) -Y １ - has a group of general formula (4). For example, an esterification product of an adduct of 1 to 20 moles of lactone and / or lactam of a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms) (meth)acryloyl monomer with the polycarboxylic acid (Z1), an esterification product of a reaction product of an adduct of 1 to 19 moles of lactone and / or lactam of a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms) (meth)acryloyl monomer with a C4 to C8 aliphatic dicarboxylic acid (anhydride) (e.g., succinic acid (anhydride), glutaric acid (anhydride), adipic acid (anhydride), etc.) with a hydroxy(poly)carboxylic acid (Z2). Examples of the hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms) (meth)acryloyl monomer include those of the above-mentioned hydroxyalkyl (meth)acryloyl monomers in which the hydroxyalkyl group has 1 to 4 carbon atoms, and examples of the lactone and lactam include those mentioned above.

[0064] (iv) -Y １ - has a group of general formula (5) For example, an esterification product of a polycarboxylic acid (Z1) with an ester of a lactone and / or lactam adduct of (meth)acrylic acid or (meth)acrylamide (1 to 19 moles) with a C2 to 20 chain aliphatic diol, and an esterification product of a polycarboxylic acid (Z1), an esterification product of a lactone and / or lactam adduct of (meth)acrylic acid or (meth)acrylamide (1 to 19 moles) with a C2 to 20 chain aliphatic diol, and an esterification product of a hydroxy(poly)carboxylic acid (Z2). Examples of lactones and lactams include those mentioned above. Examples of C2 to 20 chain aliphatic diols include ethylene glycol, propylene glycol, butanediol, pentanediol, neopentyl glycol, etc.

[0065] The ring-opening addition reaction, esterification reaction, etc. of the lactone or lactam can be carried out by a known method, and examples of the reaction conditions are the same as those for producing the monomer (a) described above.

[0066] Examples of the monomer (b), in which the polycarboxylic acid (Z1) is an aromatic polycarboxylic acid, include the following: monoesters of phthalic acid and hydroxyalkyl (C2-40) (meth)acrylate (monohydroxyethyl phthalate (meth)acrylate [mono-2-((meth)acryloyloxy)ethyl phthalate], monohydroxy-n-propyl phthalate (meth)acrylate, monohydroxyisopropyl phthalate (meth)acrylate, monohydroxy-n-butyl phthalate (meth)acrylate, monohydroxyisobutyl phthalate (meth)acrylate, monohydroxy-n-hexyl phthalate, (meth)acrylate, monohydroxy-n-octyl phthalate (meth)acrylate, monohydroxy-n-decyl phthalate (meth)acrylate, etc.), monoesters of phthalic acid and an adduct of hydroxyalkyl (C2-4) (meth)acrylate with 1 to 19 moles of alkylene (C2-4) oxide, and monoesters of phthalic acid and an adduct of hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms, preferably 2 to 3 carbon atoms) (meth)acrylate with 1 to 20 moles (preferably 1 to 5 moles) of ε-caprolactone. monoesters of phthalic acid with ethylene glycol and an ester of (meth)acrylic acid with 1 to 19 moles of ε-caprolactone adduct; monoesters of trimellitic acid with hydroxyalkyl (C2 to 40) (meth)acrylate (monohydroxyethyl trimellitate (meth)acrylate [mono-2-((meth)acryloyloxy)ethyl trimellitate], monohydroxy-n-propyl trimellitate (meth)acrylate, monohydroxyisopropyl trimellitate (meth)acrylate trimellitic acid monohydroxy-n-butyl(meth)acrylate, trimellitic acid monohydroxyisobutyl(meth)acrylate, trimellitic acid monohydroxy-n-hexyl(meth)acrylate, trimellitic acid monohydroxy-n-octyl(meth)acrylate, trimellitic acid monohydroxy-n-decyl(meth)acrylate, etc.), monoesters of trimellitic acid and hydroxyalkyl(C2-4)(meth)acrylate with 1 to 19 moles of alkylene(C2-4)oxide,Monoesters of trimellitic acid with adducts of 1 to 20 moles (preferably 1 to 5 moles) of ε-caprolactone to hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms, preferably 2 to 3 carbon atoms) (meth)acrylate, monoesters of trimellitic acid with esters of ethylene glycol with adducts of 1 to 19 moles of ε-caprolactone to (meth)acrylic acid, monoesters of pyromellitic acid and hydroxyalkyl (C2 to 40) (meth)acrylate (monohydroxyethyl pyromellitic acid (meth)acrylate [monohydroxyethyl pyromellitic acid -2-((meth)acryloyloxy)ethyl], pyromellitic acid monohydroxy-n-propyl (meth)acrylate, pyromellitic acid monohydroxyisopropyl (meth)acrylate, pyromellitic acid monohydroxy-n-butyl (meth)acrylate, pyromellitic acid monohydroxyisobutyl (meth)acrylate, pyromellitic acid monohydroxy-n-hexyl (meth)acrylate, pyromellitic acid monohydroxy-n-octyl (meth)acrylate, pyromellitic acid monohydroxy-n-decyl (meth)acrylate, etc.), pyromellitic acid monohydroxy-n-propyl (meth)acrylate, pyromellitic acid monohydroxy-n-butyl (meth)acrylate, pyromellitic acid monohydroxy-n-octyl (meth)acrylate, pyromellitic acid monohydroxy-n-decyl (meth)acrylate, etc. monoesters of pyromellitic acid with an adduct of hydroxyalkyl (C2-4) (meth)acrylate with 1 to 19 moles of alkylene (C2-4) oxide; monoesters of pyromellitic acid with an adduct of hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms, preferably 2 to 3 carbon atoms) (meth)acrylate with 1 to 20 moles (preferably 1 to 5 moles) of ε-caprolactone; monoesters of pyromellitic acid with an ester of an adduct of ε-caprolactone of 1 to 19 moles of (meth)acrylic acid with ethylene glycol; Monoesters of benzenepentacarboxylic acid monohydroxyethyl (meth)acrylate [benzenepentacarboxylic acid mono-2-((meth)acryloyloxy)ethyl], 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 monohydroxy-n-decyl(meth)acrylate, etc.), monoesters of benzenepentacarboxylic acid and hydroxyalkyl(C2-4)(meth)acrylate with 1 to 19 moles of alkylene(C2-4)oxide adduct, hydroxyalkyl(hydroxyalkyl group having 1 to 4 carbon atoms, preferably 1 to 4 carbon atoms), Monoesters of benzenepentacarboxylic acid with 1 to 20 moles (preferably 1 to 5 moles) of an adduct of (meth)acrylate with ε-caprolactone, (meth)acrylic acid with 1 to 19 moles of ε-caprolactone, and ethylene glycol, and monoesters of benzenepentacarboxylic acid with ε-caprolactone, (meth)acrylic acid with 1 to 19 moles of ε-caprolactone, monoesters of benzenepentacarboxylic acid with ε-caprolactone, monoesters of mellitic acid with hydroxyalkyl (C2-40) (meth)acrylate (monohydroxyethyl mellitic acid (meth)acrylate [mono-2-((meth)acrylic acid)], mellitic acid monohydroxy-n-propyl (meth)acrylate, mellitic acid monohydroxyisopropyl (meth)acrylate, mellitic acid monohydroxy-n-butyl (meth)acrylate, mellitic acid monohydroxyisobutyl (meth)acrylate, mellitic acid monohydroxy-n-hexyl (meth)acrylate, mellitic acid monohydroxy-n-octyl (meth)acrylate, mellitic acid monohydroxy-n-decyl (meth)acrylate, etc.), mellitic acid and hydroxy Examples of such compounds include a monoester of an alkyl (C2-4) (meth)acrylate with an adduct of 1 to 19 moles of alkylene (C2-4) oxide, a monoester of an adduct of 1 to 20 moles (preferably 1 to 5 moles) of ε-caprolactone of a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms, preferably 2 to 3 carbon atoms) (meth)acrylate with mellitic acid, and a monoester of an ester of an adduct of 1 to 19 moles of ε-caprolactone of (meth)acrylic acid with ethylene glycol with mellitic acid.

[0067] Examples of the monomer (b), in which the polyvalent carboxylic acid (Z1) is an aliphatic dicarboxylic acid, include the following: monoesters of dimethylmalonic acid and hydroxyalkyl (C2-40) (meth)acrylate (monohydroxyethyl dimethylmalonate (meth)acrylate [mono-2-((meth)acryloyloxy)ethyl dimethylmalonate], monohydroxy-n-propyl dimethylmalonate (meth)acrylate, monohydroxyisopropyl dimethylmalonate (meth)acrylate, monohydroxy-n-butyl dimethylmalonate (meth)acrylate, monohydroxyisobutyl dimethylmalonate (meth)acrylate, ) acrylate, dimethylmalonic acid monohydroxy-n-hexyl (meth)acrylate, dimethylmalonic acid monohydroxy-n-octyl (meth)acrylate, dimethylmalonic acid monohydroxy-n-decyl (meth)acrylate, etc.), monoesters of dimethylmalonic acid and alkylene (C2-4) oxide 1-19 mole adducts of hydroxyalkyl (C2-4) (meth)acrylate, hydroxyalkyl (hydroxyalkyl group having 1-4 carbon atoms, preferably 2-4 carbon atoms) (meth)acrylate monoester of an adduct of 1 to 20 moles (preferably 1 to 5 moles) of ε-caprolactone with dimethylmalonic acid, an ester of an adduct of 1 to 19 moles of ε-caprolactone with (meth)acrylic acid and ethylene glycol with dimethylmalonic acid, a monoester of 2,2-dimethylsuccinic acid with hydroxyalkyl (C2-40) (meth)acrylate (2,2-dimethylsuccinic acid monohydroxyethyl (meth)acrylate [2,2-dimethylsuccinic acid mono-2-((meth)acryloyl 2,2-dimethylsuccinic acid monohydroxy-n-propyl (meth)acrylate, 2,2-dimethylsuccinic acid monohydroxyisopropyl (meth)acrylate, 2,2-dimethylsuccinic acid monohydroxy-n-butyl (meth)acrylate, 2,2-dimethylsuccinic acid monohydroxyisobutyl (meth)acrylate, 2,2-dimethylsuccinic acid monohydroxy-n-hexyl (meth)acrylate, 2,2-dimethylsuccinic acid monohydroxy-n-octyl (meth)acrylate, 2,2-dimethylsuccinic acid monohydroxy-n-decyl (meth)acrylate, etc.), monoesters of 2,2-dimethylsuccinic acid and an adduct of hydroxyalkyl (C2-4) (meth)acrylate with 1 to 19 moles of alkylene (C2-4) oxide, monoesters of dimethylsuccinic acid and an adduct of hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms, preferably 2 to 3 carbon atoms) (meth)acrylate with 1 to 20 moles (preferably 1 to 5 moles) of ε-caprolactone, monoesters of dimethylsuccinic acid and an adduct of (meth)acrylic acid with 1 to 19 moles of ε-caprolactone and ethylene glycol monoester of 2-ethyl-2-methylsuccinic acid with 2,2-dimethylsuccinic acid, monoester of 2-ethyl-2-methylsuccinic acid with hydroxyalkyl (C2-40) (meth)acrylate (2-ethyl-2-methylsuccinic acid monohydroxyethyl (meth)acrylate [2-ethyl-2-methylsuccinic acid mono-2-((meth)acryloyloxy)ethyl], 2-ethyl-2-methylsuccinic acid monohydroxy-n-propyl (meth)acrylate, 2-ethyl-2-methylsuccinic acid monohydroxyisopropyl (meth)acrylate, 2-ethyl-2-methylsuccinic acid monohydroxyisopropyl (meth)acrylate, Monohydroxy-n-butyl succinate (meth)acrylate, 2-ethyl-2-methyl succinate monohydroxyisobutyl (meth)acrylate, 2-ethyl-2-methyl succinate monohydroxy-n-hexyl (meth)acrylate, 2-ethyl-2-methyl succinate monohydroxy-n-octyl (meth)acrylate, 2-ethyl-2-methyl succinate monohydroxy-n-decyl (meth)acrylate, etc.), alkylene (C2-4) oxides of 2-ethyl-2-methyl succinic acid and hydroxyalkyl (C2-4) (meth)acrylates 1-19 monoesters of 1 to 20 mole (preferably 1 to 5 mole) adducts of hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms, preferably 2 to 3 carbon atoms) (meth)acrylate with ε-caprolactone, and 2-ethyl-2-methylsuccinic acid; monoesters of 1 to 19 mole adducts of ε-caprolactone of (meth)acrylic acid with ethylene glycol and 2-ethyl-2-methylsuccinic acid; monoesters of 2,2-dimethylglutaric acid with hydroxyalkyl (C2 to 40) (meth)acrylate (2,2-Dimethylglutaric acid monohydroxyethyl (meth)acrylate [2,2-dimethylglutaric acid mono-2-((meth)acryloyloxy)ethyl], 2,2-dimethylglutaric acid monohydroxy-n-propyl (meth)acrylate, 2,2-dimethylglutaric acid monohydroxyisopropyl (meth)acrylate, 2,2-dimethylglutaric acid monohydroxy-n-butyl (meth)acrylate, 2,2-dimethylglutaric acid monohydroxyisobutyl (meth)acrylate, 2,2-dimethylglutaric acid monohydroxy-n-hexyl 2,2-dimethylglutaric acid monohydroxy-n-octyl (meth)acrylate, 2,2-dimethylglutaric acid monohydroxy-n-decyl (meth)acrylate, etc.), monoesters of 2,2-dimethylglutaric acid and an alkylene (C2-4) oxide adduct of 1 to 19 moles, of 2,2-dimethylglutaric acid, and hydroxyalkyl (C2-4) (meth)acrylate with 1 to 20 moles (preferably 1 to 5 moles) of ε-caprolactone. monoester of an ester of an adduct of (meth)acrylic acid with 1 to 19 moles of ε-caprolactone and ethylene glycol with 2,2-dimethylglutaric acid; monoester of 2,2-dimethyladipic acid with hydroxyalkyl (C2-40) (meth)acrylate (monohydroxyethyl 2,2-dimethyladipic acid (meth)acrylate [mono-2-((meth)acryloyloxy)ethyl 2,2-dimethyladipic acid], monohydroxyethyl 2,2-dimethyladipic acid (meth)acrylate [mono-2-((meth)acryloyloxy)ethyl 2,2-dimethyladipic acid (meth)acrylate ... n-propyl (meth)acrylate, 2,2-dimethyladipate monohydroxyisopropyl (meth)acrylate, 2,2-dimethyladipate monohydroxy-n-butyl (meth)acrylate, 2,2-dimethyladipate monohydroxyisobutyl (meth)acrylate, 2,2-dimethyladipate monohydroxy-n-hexyl (meth)acrylate, 2,2-dimethyladipate monohydroxy-n-octyl (meth)acrylate, 2,2-dimethyladipate monohydroxy-n-decyl (meth)acrylate, etc.), 2,Examples of such an ester include a monoester of 2-dimethyladipic acid and an adduct of 1 to 19 moles of alkylene (C2-4) oxide of a hydroxyalkyl (C2-4) (meth)acrylate, a monoester of 2,2-dimethyladipic acid and an adduct of 1 to 20 moles (preferably 1 to 5 moles) of ε-caprolactone of a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms, preferably 2 to 3 carbon atoms) (meth)acrylate, and a monoester of 2,2-dimethyladipic acid and an ester of ethylene glycol and an adduct of 1 to 19 moles of ε-caprolactone of (meth)acrylic acid.

[0068] As examples of the monomer (b), the following can be mentioned, in which the hydroxy(poly)carboxylic acid (Z2) is a chain aliphatic hydroxycarboxylic acid. esters of carboxyalkyl (carboxyalkyl group having 3 to 21 carbon atoms) (meth)acryloyl monomers {e.g., 3-carboxypropyl (meth)acrylate, 5-((meth)acryloyloxy)pentanoic acid, 6-((meth)acryloyloxy)hexanoic acid, 7-((meth)acryloyloxy)heptanoic acid, 8-((meth)acryloyloxy)octanoic acid, 9-((meth)acryloyloxy)nonanoic acid, 10-((meth)acryloyloxy)decanoic acid, etc.} with chain aliphatic hydroxycarboxylic acids (e.g., hydroxypivalic acid, 2-hydroxyisobutyric acid, 2-methylglyceric acid, isomalic acid, 2,2-dimethyl-6-hydroxyhexanoic acid, 2,2-dimethyl-7-hydroxyheptanoic acid, 2,2-dimethyl-8-hydroxyoctanoic acid, etc.); ε-caprolactone of (meth)acrylic acid; Examples of the ester include an ester of an acrylate adduct with a chain aliphatic hydroxycarboxylic acid (for example, hydroxypivalic acid, 2-hydroxyisobutyric acid, 2-methylglyceric acid, isomalic acid, 2,2-dimethyl-6-hydroxyhexanoic acid, 2,2-dimethyl-7-hydroxyheptanoic acid, and 2,2-dimethyl-8-hydroxyoctanoic acid); and an ester of a hydroxyalkyl (hydroxyalkyl group having 1 to 4 carbon atoms) (meth)acrylate with an aliphatic dicarboxylic acid (anhydride) (for example, maleic anhydride) with a chain aliphatic hydroxycarboxylic acid (for example, hydroxypivalic acid, 2-hydroxyisobutyric acid, 2-methylglyceric acid, isomalic acid, 2,2-dimethyl-6-hydroxyhexanoic acid, 2,2-dimethyl-7-hydroxyheptanoic acid, and 2,2-dimethyl-8-hydroxyoctanoic acid).

[0069] As examples of the monomer (b), the following can be mentioned, in which the hydroxy(poly)carboxylic acid (Z2) is an alicyclic group-containing hydroxycarboxylic acid.Carboxyalkyl (carboxyalkyl group having 3 to 21 carbon atoms) (meth)acryloyl monomers {e.g., 3-carboxypropyl (meth)acrylate, 5-((meth)acryloyloxy)pentanoic acid, 6-((meth)acryloyloxy)hexanoic acid, 7-((meth)acryloyloxy)heptanoic acid, 8-((meth)acryloyloxy)octanoic acid, 9-((meth)acryloyloxy)nonanoic acid, 10-((meth)acryloyloxy)decanoic acid, etc.} and alicyclic group-containing hydroxycarboxylic acids (e.g., 2-hydroxy-1- esters of α-hydroxymethylcyclohexane-1-carboxylic acid, ... esters of hydroxyalkyl (hydroxyalkyl groups having 1 to 4 carbon atoms) (meth)acrylates and aliphatic dicarboxylic acids (anhydrides) (e.g., maleic anhydride) with alicyclic group-containing hydroxycarboxylic acids (e.g., 2-hydroxy-1-methylcyclohexane-1-carboxylic acid, 3-hydroxy-1-methylcyclohexane-1-carboxylic acid, 4-hydroxy-1-methylcyclohexane-1-carboxylic acid, 2-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, 3-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, 4-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, etc.); esters of hydroxyalkyl (hydroxyalkyl groups having 1 to 4 carbon atoms) (meth)acrylates and aliphatic dicarboxylic acids (anhydrides) (e.g., maleic anhydride) with alicyclic group-containing hydroxycarboxylic acids (e.g., 2-hydroxy-1-methylcyclohexane-1-carboxylic acid, 3-hydroxy-1-methylcyclohexane-1-carboxylic acid, 4-hydroxy-1-methylcyclohexane-1-carboxylic acid, 2-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, 3-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, 4-hydroxymethyl-1-methylcyclohexane-1-carboxylic acid, etc.).

[0070] It can be confirmed from the chemical structure of the raw material used that no hydrogen atom is bonded to the carbon atom at the α-position relative to the carbonyl group of the carboxy group of the monomer (b). １３ This can also be confirmed by measuring C-NMR. Specifically, by two-dimensional NMR analysis, １３ C- １３ By checking the correlation between C, the state of the carbon atom adjacent to the carboxyl group (which has a peak at 160-185 ppm) can be determined. The fewer the number of hydrogen atoms on a carbon atom, １３ Since the C-NMR spectrum is shifted to the high ppm side, it can be confirmed that no hydrogen atom is bonded to the carbon atom adjacent to the carboxy group.

[0071] It is preferred that the monomer (b) is a compound represented by general formula (2), and the polycarboxylic acid (Z1) is at least one selected from the group consisting of phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, dimethylmalonic acid, 2,2-dimethylsuccinic acid, 2-ethyl-2-methylsuccinic acid, 2,2-dimethylglutaric acid, and 2,2-dimethyladipic acid.

[0072] From the viewpoint of anti-wear properties, the molecular formula weight or Mn of the monomer (b) is preferably 300 to 950, more preferably 300 to 850, and particularly preferably 300 to 800. The Mn of the monomer (b) can be measured under the above-mentioned conditions.

[0073] The structural unit derived from the monomer (b) (a structure in which the polymerizable unsaturated group of the monomer (b) is reacted to form a single bond) preferably has a specific SP value from the viewpoint of solubility in the lubricating base oil. The SP value of the structural unit derived from the monomer (b) is preferably 8 to 13 (cal / cm ３ ) １／２ and more preferably 9 to 12.5 (cal / cm ３ ) １／２ and particularly preferably 10 to 12 (cal / cm ３ ) １／２When two or more types of monomers (b) are used in combination as constituent monomers, it is preferable that the SP values ​​of the constituent units derived from each monomer (b) are calculated by the above-mentioned method, and the weighted average based on the weight fraction of each monomer (b) falls within the above-mentioned range.

[0074] The copolymer (A) may further contain, as a constituent monomer, a monomer (c) represented by the following general formula (6): When the copolymer (A) contains the monomer (c) as a constituent monomer, the copolymer tends to be easily soluble in the base oil, which is preferable. [In general formula (6), R １０ is a hydrogen atom or a methyl group; -X ７ - is a group represented by -O- or -NH-; R １１ is a linear or branched alkyl group having 5 to 44 carbon atoms.

[0075] In general formula (6), R １０ is a hydrogen atom or a methyl group, and is preferably a methyl group from the viewpoint of solubility.

[0076] In the general formula (6), -X ７ - is a group represented by -O- or -NH-, and is preferably -O- from the viewpoint of anti-wear properties.

[0077] In general formula (6), R １１is a linear or branched alkyl group having 5 to 44 carbon atoms. Specific examples include an n-pentyl group, an isopentyl group, an n-hexyl group, an isohexyl group, an n-heptyl group, an isoheptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an isononyl group, an n-decyl group, an isodecyl group, an n-undecyl group, an isoundecyl group, an n-dodecyl group, an isododecyl group, an n-tridecyl group, an isotridecyl group, and an n-tetradecyl group. , 2-ethyldodecyl group, n-pentadecyl group, 2-methyltetradecyl group, n-hexadecyl group, isohexadecyl group, n-heptadecyl group, isoheptadecyl group, 2-ethylpentadecyl group, 2-octylnonyl group, 2-(3-methylhexyl)-7-methyl-nonyl group, n-octadecyl group, isooctadecyl group, 2-hexylundecyl group, 2-ethyl Examples thereof include a heptadecyl group, a 1-hexyltridecyl group, an n-icosyl group, a 2-octylundecyl group, an isoicosyl group, a 1-undecyldodecyl group, a 1-octylpentadecyl group, a 2-decyltridecyl group, an n-tetracosyl group, a 2-decyltetradecyl group, a 2-dodecylpentadecyl group, a 2-heptylicosyl group, a 2-dodecylhexadecyl group, an n-triacontyl group, a 2-tetradecyloctadecyl group, an n-hexatriacontyl group, an n-tetracontyl group, a 2-ethyltetracontyl group, and a residue obtained by removing a hydroxyl group from an oxoalcohol obtained from an olefin [for example, a propylene oligomer (dimer to 14-mer), an ethylene / propylene oligomer (dimer to 20-mer), an isobutene oligomer (dimer to 10-mer), and the like].

[0078] R １１ From the viewpoint of solubility in the base oil, the alkyl group is preferably a linear or branched C8-34 alkyl group, more preferably a linear or branched C8-32 alkyl group, particularly preferably a linear or branched C10-32 alkyl group, and most preferably a linear C10-22 alkyl group or a branched C12-32 alkyl group.

[0079] In the present invention, the copolymer (A) may contain, as constituent monomers, a (meth)acryloyl monomer (d) having an alkyl group having 1 to 4 carbon atoms other than the monomers (a) to (c), a nitrogen atom-containing vinyl monomer (e), a hydroxyl group-containing vinyl monomer (f) other than the monomer (a), a cyclic ether group-containing monomer (g), a carbonyl group-containing monomer (h) other than the monomers (a) and (b), and a phosphorus atom-containing vinyl monomer (i).

[0080] Examples of the (meth)acryloyl monomer (d) having an alkyl group of 1 to 4 carbon atoms include (meth)acrylates having a C1 to 4 alkyl group and (meth)acrylamides having a C1 to 4 alkyl group. More specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, and N-butyl (meth)acrylamide. From the viewpoint of anti-wear properties, the monomer (d) is preferably a (meth)acrylate having a C1 to 4 alkyl group, more preferably a (meth)acrylate having a C1 to 4 linear alkyl group, and particularly preferably methyl (meth)acrylate and butyl (meth)acrylate.

[0081] Examples of the nitrogen atom-containing vinyl monomer (e) include amide group-containing vinyl monomers (e1) such as (meth)acrylamide and monoalkylamino(meth)acrylamide; nitro group-containing monomers (e2) such as 4-nitrostyrene; primary, secondary, or tertiary amino group-containing vinyl monomers (e3) such as (meth)allylamine, methylaminoethyl(meth)acrylate, and dimethylaminoethyl(meth)acrylate; and nitrile group-containing vinyl monomers (e4) such as (meth)acrylonitrile.

[0082] Examples of the hydroxyl group-containing vinyl monomer (f) include N,N-dihydroxymethyl(meth)acrylamide, (meth)allyl alcohol, polyhydric (preferably dihydric to hexahydric) alcohol (C2-6) mono(meth)acrylic acid esters {e.g., 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, glycerin mono(meth)acrylate, pentaerythritol (mono)methacrylate, xylitol mono(meth)acrylate, sorbitol mono(meth)acrylate, etc.}.

[0083] Examples of the cyclic ether group-containing monomer (g) include glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, tetrahydrofuranyl methoxyethyl (meth)acrylate, tetrahydrofuranyl methoxypropyl (meth)acrylate, tetrahydrofuranyl methoxyisopropyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, 2-[(2-tetrahydropyranyl)oxy]ethyl (meth)acrylate, 1,3-dioxane-(meth)acrylate, and (1,3-dioxolan-4-yl)methyl (meth)acrylate.

[0084] The carbonyl group-containing monomer (h) includes monomers other than the monomers (a) and (b) having a carbonyl group other than a carbonyl group derived from a (meth)acryloyl group, and examples thereof include 4-oxohexyl (meth)acrylate, 2-acetoxyethyl (meth)acrylate, 2-(acetoacetyloxy)ethyl (meth)acrylate (also described as ethylene glycol monoacetoacetate mono(meth)acrylate), 1-methyl-2-[(1-oxo-2-propenyl)oxy]ethyl 3-oxobutanoate, 1-methyl-3-[2-((meth)acryloyloxy)ethyl] malonate, and 1-ethyl-3-[2-((meth)acryloyloxy)ethyl] malonate.

[0085] Examples of the phosphorus atom-containing monomer (i) include phosphate ester group-containing monomers (g1) such as (meth)acryloyloxyethyl phosphate and isopropenyl phosphate; and phosphono group-containing monomers (g2) such as (meth)acryloyloxyethyl phosphonic acid and allylphosphonic acid.

[0086] The weight proportion of the monomer (a) constituting the copolymer (A) is preferably 5 to 49.5% by weight, more preferably 15 to 43% by weight, and particularly preferably 24 to 36% by weight, based on the total weight of the monomers constituting (A), from the viewpoint of anti-wear properties. The weight proportion of the monomer (b) constituting the copolymer (A) is preferably 0.5 to 20% by weight, more preferably 2 to 10% by weight, and particularly preferably 4 to 6% by weight, based on the total weight of the monomers constituting (A), from the viewpoint of anti-wear properties.

[0087] When copolymer (A) contains any of the above monomers (c) to (i) as a constituent monomer, the preferred weight proportions of the monomers are as follows. From the viewpoint of anti-wear properties, the weight proportion of monomer (c) is preferably 50 to 85 wt %, more preferably 55 to 80 wt %, and particularly preferably 60 to 70 wt %, based on the total weight of the monomers constituting copolymer (A). From the viewpoint of anti-wear properties, the weight proportion of monomer (d) is preferably 30 wt % or less, more preferably 25 wt % or less, and particularly preferably 5 to 25 wt %, based on the total weight of the monomers constituting copolymer (A). From the viewpoint of anti-wear properties, the weight proportion of monomer (e) is preferably 10 wt % or less, more preferably 7 wt % or less, and particularly preferably 5 wt % or less, based on the total weight of the monomers constituting copolymer (A). From the viewpoint of anti-wear properties, the weight proportion of the monomer (f) 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 monomers constituting the copolymer (A). From the viewpoint of anti-wear properties, the weight proportion of the monomer (g) 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 monomers constituting the copolymer (A). From the viewpoint of anti-wear properties, the weight proportion of the monomer (h) 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 monomers constituting the copolymer (A). From the viewpoint of anti-wear properties, the weight proportion of the monomer (i) 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 monomers constituting the copolymer (A). From the viewpoint of anti-wear properties, the total weight proportion of the monomers (e) to (i) is preferably 10% by weight or less, more preferably 1 to 7% by weight, based on the total weight of the monomers constituting the copolymer (A).

[0088] From the viewpoint of anti-wear properties, the total weight proportion of the monomers (a) and (b) constituting the copolymer (A) is preferably 15 to 50% by weight, more preferably 20 to 45% by weight, and particularly preferably 30 to 40% by weight, based on the total weight of the constituent monomers of the copolymer (A).

[0089] When the copolymer (A) also contains the monomer (c) as a constituent monomer, it is preferred that the total weight proportion of the monomers (a) and (b) constituting the copolymer (A) is 15 to 50% by weight based on the total weight of the constituent monomers of the copolymer (A), and that the weight proportion of the monomer (c) is 50 to 85% by weight based on the total weight of the constituent monomers of the copolymer (A).

[0090] The weight ratio (a / b) of the monomer (a) to the monomer (b) constituting the copolymer (A) is preferably 0.25 to 90, more preferably 1 to 9, even more preferably 3 to 8, and particularly preferably 4 to 7, from the viewpoints of anti-wear properties and oil solubility.

[0091] The SP value of the copolymer (A) is 8.5 to 11.5 (cal / cm) from the viewpoint of solubility in the base oil. ３ ) １／２ is preferable, and more preferably 8.7 to 11.0 (cal / cm ３ ) １／２ , and more preferably 8.9 to 10.5 (cal / cm ３ ) １／２ and particularly preferably 9.2 to 10.2 (cal / cm ３ ) １／２ is.

[0092] From the viewpoint of anti-wear properties, the number of moles of carboxy groups in 1 g of copolymer (A) is preferably 0.008 to 0.35 mmol / g, more preferably 0.03 to 0.25 mmol / g, and particularly preferably 0.06 to 0.17 mmol / g.

[0093] The number of moles of hydroxy groups in 1 g of copolymer (A) is preferably 0.1 to 2.0 mmol / g, more preferably 0.3 to 1.7 mmol / g, and particularly preferably 0.5 to 1.4 mmol / g, from the viewpoint of anti-wear properties.

[0094] The SP value of copolymer (A) means a weighted average value calculated by calculating the SP value of the structural units derived from each monomer constituting copolymer (A) using the above-mentioned method for calculating the SP value (a structure in which a carbon-carbon double bond (e.g., a vinyl group) contained in a polymerizable unsaturated group of each monomer constituting copolymer (A) becomes a single bond through a polymerization reaction) based on the weight fraction of each structural monomer at the time of charging. For example, when the monomer is methyl methacrylate, the structural unit derived from methyl methacrylate has, as an atomic group, CH ３ 2 pieces, CH ２ 1, 1 C, CO ２ Since there is one unit, the SP value of the structural unit derived from methyl methacrylate is 9.933 (cal / cm ３ ) １／２ It can be seen that ΣΔe ｉ =1125×2+1180+350+4300=8080 ΣΔv ｉ = 33.5 x 2 + 16.1 - 19.2 + 18.0 = 81.9 SP value = (8080 / 81.9) １／２ =9.933(cal / cm ３ ) １／２ Similarly, the SP value of the structural unit derived from ethyl methacrylate is 9.721 (cal / cm ３ ) １／２ In the case of a copolymer that is a polymer of 50% by weight of methyl methacrylate and 50% by weight of ethyl methacrylate, the SP value is calculated by taking a weighted average based on the weight fraction of the SP values ​​of the constituent units derived from each monomer, as follows: SP value = (9.933 x 50 + 9.721 x 50) / 100 = 9.827 (cal / cm ３ ) １／２ The SP value of the copolymer (A) can be adjusted to a desired range by appropriately adjusting the monomers and weight fractions used. Specifically, the SP value can be reduced by using a large amount of monomers having a long alkyl group carbon number, and the SP value can be increased by using a large amount of monomers having a short alkyl group carbon number or monomers having many polar groups (-O-, -NH-, -C(=O)O-, -OC(=O)-, -C(=O)NH- and -NHC(=O)-, carboxy groups, hydroxy groups, etc.).

[0095] From the viewpoint of viscosity (handleability), the Mw of the copolymer (A) is preferably from 5,000 to 500,000, more preferably from 10,000 to 35,000, and particularly preferably from 15,000 to 30,000.

[0096] Copolymer (A) can be obtained by known production methods, specifically, a method of solution polymerization of the above-mentioned monomers in a solvent in the presence of a polymerization catalyst. Examples of solvents include toluene, xylene, C9-10 alkylbenzene, methyl ethyl ketone, ethyl acetate, 2-propanol, and the base oils described below. Examples of 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). If necessary, known chain transfer agents (such as C2-20 alkyl mercaptans) can also be used. The polymerization temperature is preferably 25 to 140°C, more preferably 50 to 120°C. In addition to the above-mentioned solution polymerization, copolymer (A) can also be obtained by bulk polymerization, emulsion polymerization, or suspension polymerization. When the copolymer (A) is a copolymer, the polymerization form may be either a random addition copolymer or an alternating copolymer, and may also be either a graft copolymer or a block copolymer.

[0097] The antiwear agent of the present invention may contain the copolymer (A), but may further contain a base oil from the viewpoint of handleability (ease of addition to a lubricating oil composition, etc.). Examples of the base oil include mineral oils (solvent refined oils, paraffin oils, high viscosity index oils containing isoparaffins, high viscosity index oils obtained by hydrocracking isoparaffins, and naphthenic oils), synthetic lubricating oils (hydrocarbon-based synthetic lubricating oils (poly-α-olefin-based synthetic lubricating oils, etc.), and ester-based synthetic lubricating oils), and mixtures thereof. Of these, mineral oils are preferred from the viewpoint of insulating properties.

[0098] The content of copolymer (A) in the antiwear agent is preferably 20 to 90 wt %, more preferably 30 to 80 wt %, based on the weight of the antiwear agent, from the viewpoint of handleability (ease of addition to a lubricating oil composition, etc.). The content of base oil in the antiwear agent is preferably 10 to 80 wt %, more preferably 20 to 70 wt %, based on the weight of the antiwear agent, from the viewpoint of handleability (ease of addition to a lubricating oil composition, etc.).

[0099] The anti-wear agent of the present invention can achieve both anti-wear properties and storage stability, and is therefore suitable for use in gear oils (differential oils, industrial gear oils, etc.), MTFs, transmission oils [ATFs, belt-CVTFs, etc.], traction oils (toroidal-CVTFs, etc.), shock absorber oils, power steering oils, hydraulic oils (construction machinery hydraulic oils, industrial hydraulic oils, etc.), engine oils, etc., and is preferably used as an anti-wear agent for transmission oils, electric motor oils, and dual-purpose oils for transmissions and electric motors in electric vehicles or hybrid vehicles, and particularly preferably used as an anti-wear agent for dual-purpose oils for transmissions and electric motors in electric vehicles or hybrid vehicles.

[0100] <Lubricating Oil Composition> The lubricating oil composition of the present invention contains the antiwear agent of the present invention and a base oil. When a base oil is contained in the antiwear agent, the base oil may be the same as or different from the base oil in the antiwear agent. Examples of base oils used in the lubricating oil composition include mineral oils (solvent refined oils, paraffin oils, high viscosity index oils containing isoparaffins, high viscosity index oils obtained by hydrocracking isoparaffins, and naphthenic oils), synthetic lubricating oils (hydrocarbon-based synthetic lubricating oils (poly-α-olefin-based synthetic lubricating oils, etc.) and ester-based synthetic lubricating oils), and mixtures thereof. Of these, mineral oils are preferred from the viewpoint of insulating properties.

[0101] The kinematic viscosity of the base oil at 100°C (measured according to JIS-K2283 (2000)) is preferably 1 to 10 mmHg from the viewpoint of the solubility of the copolymer (A). ２ / s, and more preferably 1 to 4 mm ２The viscosity index of the base oil (measured in accordance with JIS-K2283 (2000)) is preferably 100 or more, and more preferably 110 or more, from the viewpoint of improving the viscosity index.

[0102] The cloud point of the base oil (measured according to JIS-K2269 (1987)) is preferably −5° C. or lower, and more preferably −15° C. or lower. When the cloud point of the base oil is within this range, the low-temperature viscosity of the lubricating oil composition is good.

[0103] From the viewpoint of compatibility, the absolute value of the difference (ΔSP) between the SP value of the copolymer (A) and the SP value of the base oil in the lubricating oil composition is preferably 0.5 to 3.2 (cal / cm ３ ) １／２ and more preferably 0.6 to 2.5 (cal / cm ３ ) １／２ , and particularly preferably 0.6 to 2.1 (cal / cm ３ ) １／２ and most preferably 0.7 to 1.7 (cal / cm ３ ) １／２ is.

[0104] From the viewpoint of anti-wear properties, 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.

[0105] The viscosity index (measured in accordance with JIS-K2283 (2000)) of the lubricating oil composition of the present invention is preferably 110 or higher, more preferably 120 or higher. The kinematic viscosity (measured in accordance with JIS-K2283 (2000)) of the lubricating oil composition of the present invention at 100°C is preferably 1.1 to 10.1 mm ２ / s, and more preferably 1.1 to 4.1 mm ２ The kinematic viscosity of the lubricating oil composition of the present invention at 40°C (measured in accordance with JIS-K2283 (2000)) is preferably 4 to 50 mm ２ / s, and more preferably 4 to 20 mm ２ / s.

[0106] The lubricating oil composition of the present invention is suitable for use in gear oils (differential oils, industrial gear oils, etc.), MTFs, transmission oils [ATFs, belt-CVTFs, etc.], traction oils (toroidal-CVTFs, etc.), shock absorber oils, power steering oils, hydraulic oils (hydraulic oils for construction machinery, hydraulic oils for industrial use, etc.), engine oils, etc., and is preferably useful as transmission oils, electric motor oils, and dual-purpose oils for transmissions and electric motors in electric vehicles or hybrid vehicles, and particularly preferably as dual-purpose oils for transmissions and electric motors in electric vehicles or hybrid vehicles.

[0107] The lubricating oil composition of the present invention may contain various additives. Examples of the additives include at least one selected from the group consisting of viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, metal-based friction and wear modifiers, extreme pressure agents, antifoaming agents, demulsifiers, corrosion inhibitors, and pour point depressants, and specific examples include the following. (1) Viscosity index improvers: (C1-7) alkyl (meth)acrylate / (C8-40) linear or branched alkyl (meth)acrylate copolymers, dispersant monomers (amine monomers, etc.) / (C1-7) alkyl (meth)acrylate / (C8-40) linear or branched alkyl (meth)acrylate copolymers, hydroxy group-containing monomers / (C1-7) alkyl (meth)acrylate / (C8-40) linear or branched alkyl (meth)acrylate copolymers, comb polymers [(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 / hydrogenated isoprene copolymer, etc.; (2) Detergents: basic, overbased or neutral metal salts [overbased or alkaline earth metal salts of sulfonates (petroleum sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, etc.)], salicylates, phenates, naphthenates, carbonates, phosphonates, and mixtures thereof; (3) Dispersants: succinimides (bis- or mono-polybutenyl succinimides), Mannich condensation products, borates, and the like; (4) Antioxidants: hindered phenols and aromatic secondary amines, and the like; (5) Oiliness improvers: long-chain fatty acids and their esters (oleic acid and oleic acid esters, etc.), long-chain amines and their amides (oleylamine, oleylamide, etc.), and the like; (6) Metal-based friction and wear modifiers: Molybdenum and zinc compounds (molybdenum dithiophosphate, molybdenum dithiocarbamate, zinc dialkyldithiophosphate, etc.);(7) Extreme pressure agents: sulfur-based compounds (mono- or disulfides, sulfoxides, and sulfur phosphate compounds), phosphate compounds, and chlorine-based compounds (chlorinated paraffins, etc.); (8) Antifoaming agents: silicone oils, metal soaps, fatty acid esters, and phosphate compounds; (9) Demulsifiers: quaternary ammonium salts (tetraalkylammonium salts, etc.), sulfated oils, and phosphates (phosphates of polyoxyethylene-containing nonionic surfactants, etc.); (10) Corrosion inhibitors: nitrogen-containing compounds (benzotriazole, 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate, etc.); (11) Pour point depressants: polyalkyl methacrylates, polyalkyl acrylates, polyalkylstyrenes, polyvinyl acetates, etc.;

[0108] The lubricating oil composition of the present invention preferably contains at least one additive selected from the group consisting of viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, metal-based friction and wear modifiers, extreme pressure agents, antifoaming agents, demulsifiers, corrosion inhibitors, and pour point depressants. The lubricating oil composition may contain only one of these additives, or may contain two or more additives as needed. The content of each of these additives is preferably 0.1 to 15 wt % based on the total weight of the lubricating oil composition. The total content of each additive is preferably 0.1 to 30 wt %, more preferably 0.3 to 20 wt %, and even more preferably 3 to 10 wt %, based on the total weight of the lubricating oil composition.

[0109] The present specification discloses the following: The present disclosure (1) is an anti-wear agent containing a copolymer (A) having, as essential constituent monomers, a monomer (a) represented by the following general formula (1) and a monomer (b) represented by the following general formula (2) or (2'), wherein, in the monomers constituting the copolymer (A), the average value of p per mole of the monomer (a) is 1 to 4: [In general formula (1), A １ represents a polymerizable unsaturated group having 2 to 5 carbon atoms; -X １ -, -X ２ - and -X ３ - each independently represents a group represented by -O- or -NH-; R１ is an alkylene group having 1 to 4 carbon atoms; R ２ is an alkylene group having 2 to 20 carbon atoms; p is an integer of 1 to 100, and when p is 2 or more, a plurality of R ２ and X ３ may be the same or different; R ３ represents a hydrogen atom, a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, a phenyl group in which a 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 a hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms.] [In the general formulas (2) and (2′), A ２ represents a polymerizable unsaturated group having 2 to 5 carbon atoms; -X ４ - is a group represented by -O- or -NH-; -Y １ - represents a divalent hydrocarbon group having 2 to 400 carbon atoms, some of the bonds of which may be substituted with at least one bond selected from the group consisting of -O-, -NH-, -C(=O)O-, -OC(=O)-, -C(=O)NH-, and -NHC(=O)-; Z １ represents a residue obtained by removing one carboxy group (X1) from a polycarboxylic acid (Z1), and the polycarboxylic acid (Z1) is a compound in which a hydrogen atom is not bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X2) other than the (X1); Z ２ represents a residue obtained by removing one hydroxy group from a hydroxy(poly)carboxylic acid (Z2), and the hydroxy(poly)carboxylic acid (Z2) is a compound in which no hydrogen atom is bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X3) of (Z2).]

[0110] The present disclosure (2) is the anti-wear agent according to the present disclosure (1), wherein the weight ratio (a / b) of the monomer (a) to the monomer (b) constituting the copolymer (A) is 0.25 to 90.

[0111] The present disclosure (3) relates to -Y in the general formulas (2) and (2′). １The antiwear agent according to the present disclosure (1) or (2), wherein -(R) is an alkylene group having 2 to 20 carbon atoms or a group represented by the following general formula (3), the following general formula (4), or the following general formula (5): ４ O) ｑ -R ５ - (3) [In general formula (3), R ４ O is an alkyleneoxy group having 2 to 4 carbon atoms, q is an integer from 1 to 20, and when q is 2 or more, there are a plurality of R ４ may be the same or different; R ５ is an alkylene group having 2 to 4 carbon atoms. ６ -(X ５ -C(=O)-R ７ ) ｒ - (4) [In general formula (4), R ６ represents an alkylene group having 1 to 4 carbon atoms; X ５ represents a group represented by —O— or —NH—, R ７ represents an alkylene group having 2 to 20 carbon atoms, r is an integer of 1 to 20, and when r is 2 or more, there are a plurality of R ７ and X ５ may be the same or different.] -(R ８ -C(=O)-X ６ ) ｓ -R ９ - (5) [In general formula (5), R ８ represents an alkylene group having 2 to 20 carbon atoms, and -X ６ - represents a group represented by -O- or -NH-, s is an integer of 1 to 20, and when s is 2 or more, there are a plurality of R ８ and X ６ may be the same or different, R ９ is an alkylene group having 2 to 20 carbon atoms.

[0112] The present disclosure (4) is the antiwear agent according to any one of the present disclosures (1) to (3), wherein the copolymer (A) contains a monomer (c) represented by the following general formula (6) as a constituent monomer: [In general formula (6), R １０ is a hydrogen atom or a methyl group; -X ７ - is a group represented by -O- or -NH-; R １１is a linear or branched alkyl group having 5 to 44 carbon atoms.

[0113] The present disclosure (5) is the anti-wear agent according to the present disclosure (4), wherein the total weight ratio of the monomers (a) and (b) constituting the copolymer (A) is 15 to 50% by weight based on the total weight of the constituent monomers of the copolymer (A), and the weight ratio of the monomer (c) is 50 to 85% by weight based on the total weight of the constituent monomers of the copolymer (A).

[0114] The present disclosure (6) is the anti-wear agent according to any one of the present disclosures (1) to (5), wherein the monomer (b) is a compound represented by general formula (2), and the polyvalent carboxylic acid (Z1) is at least one selected from the group consisting of phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, dimethylmalonic acid, 2,2-dimethylsuccinic acid, 2-ethyl-2-methylsuccinic acid, 2,2-dimethylglutaric acid, and 2,2-dimethyladipic acid.

[0115] The present disclosure (7) is the antiwear agent according to any one of the present disclosures (1) to (6), wherein the weight average molecular weight of the copolymer (A) is 5,000 to 500,000.

[0116] The present disclosure (8) is a lubricating oil composition comprising the antiwear agent according to any one of the present disclosures (1) to (7) and a base oil.

[0117] The present disclosure (9) is a method for producing a viscous oil having a kinematic viscosity of 1 to 4 mm at 100 ° C. ２ / s.

[0118] The present disclosure (10) is the lubricating oil composition according to the present disclosure (8) or (9), further comprising at least one selected from the group consisting of a viscosity index improver, a detergent, a dispersant, an antioxidant, an oiliness improver, a metal-based friction and wear modifier, an extreme pressure agent, an antifoaming agent, a demulsifier, a corrosion inhibitor, and a pour point depressant.

[0119] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0120] The various monomers used in the examples and comparative examples are as follows. The SP value refers to the SP value of the constituent units derived from the monomer. The SP value is shown in Table 2. <Production Example 1> [Production of Monomer (a-1)] 260.3 parts by weight (2.0 parts by mole) of 2-hydroxyethyl methacrylate (hereinafter abbreviated as HEMA), 684.8 parts by weight (6.0 parts by mole) of ε-caprolactone, 3.7 parts by weight (0.03 parts by mole) of hydroquinone monomethyl ether, and 0.27 parts by weight of butyl tris(2-ethylhexanoyloxy)tin were charged into a reaction vessel equipped with a temperature controller, a stirring blade, a pressure reducing device, a Dimroth condenser, a fractionating column, a distillate receiving flask, and a nitrogen inlet and outlet, and the mixture was heated to 115°C with stirring while air was passed through. Next, the mixture was reacted at 115°C for 8 hours, and the distilled water was separated. The mixture was further cooled to 25°C, and １ The esterification reaction product was confirmed by H-NMR (yield: 100 mol%). Monomer (a-1) is a compound represented by general formula (1), and A in general formula (1) １ is a methacryloyl group, -X １ -, -X ２ - and -X ３ - is a group represented by -O-, R １ is an ethylene group, the molar average value of p is 3, R ２ is a pentylene group, R ３ is a hydrogen atom. The SP value is 11.04.

[0121] <Production Example 2> [Production of Monomer (a-2)] 260.3 parts by weight (2.0 parts by mole) of 2-hydroxyethyl methacrylate (HEMA), 913.2 parts by weight (8.0 parts by mole) of ε-caprolactone, 3.7 parts by weight (0.03 parts by mole) of hydroquinone monomethyl ether, and 0.27 parts by weight of butyl tris(2-ethylhexanoyloxy)tin were charged into a reaction vessel equipped with a temperature controller, a stirring blade, a pressure reducing device, a Dimroth condenser, a fractionating column, a distillate receiving flask, and a nitrogen inlet and outlet, and the mixture was heated to 115°C with stirring while air was passed through. The mixture was then reacted at 115°C for 8 hours, and the distilled water was separated. The mixture was then further cooled to 25°C. １ The esterification reaction product was confirmed by H-NMR (yield: 100 mol%). Monomer (a-2) is a compound represented by general formula (1), and A in general formula (1)１ is a methacryloyl group, -X １ -, -X ２ - and -X ３ - is a group represented by -O-, R １ is an ethylene group, the molar average value of p is 4, R ２ is a pentylene group, R ３ is a hydrogen atom. The SP value is 10.87.

[0122] <Production Example 3> [Production of Monomer (a-3)] 260.3 parts by weight (2.0 parts by mole) of 2-hydroxyethyl methacrylate (HEMA), 228.3 parts by weight (2.0 parts by mole) of ε-caprolactone, 3.7 parts by weight (0.03 parts by mole) of hydroquinone monomethyl ether, and 0.27 parts by weight of butyl tris(2-ethylhexanoyloxy)tin were charged into a reaction vessel equipped with a temperature controller, a stirring blade, a pressure reducing device, a Dimroth condenser, a fractionating column, a distillate receiving flask, and a nitrogen inlet and outlet, and the mixture was heated to 115°C with stirring while air was passed through. The mixture was then reacted at 115°C for 8 hours, and the distilled water was separated. The mixture was then further cooled to 25°C. １ The esterification reaction product was confirmed by H-NMR (yield: 53 mol%). Thereafter, 2-hydroxyethyl methacrylate (HEMA), which remained as an impurity at 47 mol%, was removed by silica column chromatography. Monomer (a-3) is a compound represented by general formula (1), and A in general formula (1) １ is a methacryloyl group, -X １ -, -X ２ - and -X ３ - is a group represented by -O-, R １ is an ethylene group, the molar average value of p is 1.9, R ２ is a pentylene group, R ３ is a hydrogen atom. The SP value is 11.37.

[0123] <Production Example 4> [Production of Monomer (a-4)] 232.2 parts by weight (2.0 parts by mole) of 2-hydroxyethyl acrylate (hereinafter abbreviated as HEA), 456.6 parts by weight (4.0 parts by mole) of ε-caprolactone, 3.7 parts by weight (0.03 parts by mole) of hydroquinone monomethyl ether, and 0.27 parts by weight of butyl tris(2-ethylhexanoyloxy)tin were charged into a reaction vessel equipped with a temperature controller, a stirring blade, a pressure reducing device, a Dimroth condenser, a fractionating column, a distillate receiving flask, and a nitrogen inlet and outlet, and the mixture was heated to 115°C with stirring while passing air through. The mixture was then reacted at 115°C for 8 hours, and the distilled water was separated. The mixture was then further cooled to 25°C. １ The esterification reaction product was confirmed by H-NMR (yield: 76 mol%). Thereafter, 24 mol% of 2-hydroxyethyl acrylate (HEA) remaining as an impurity was removed by silica column chromatography. Monomer (a-4) is a compound represented by general formula (1), and A in general formula (1) １ is an acryloyl group, -X １ -, -X ２ - and -X ３ - is a group represented by -O-, R １ is an ethylene group, the molar average value of p is 2.6, R ２ is a pentylene group, R ３ is a hydrogen atom. The SP value is 11.32.

[0124] <Production Example 5> [Production of Monomer (b-1)] A reaction vessel equipped with a temperature controller, a stirring blade, a pressure reducing device, a Dimroth condenser, a fractionating column, a distillate receiving flask, and a nitrogen inlet and outlet was charged with 94.4 parts by weight (0.2 parts by mole) of Monomer (a-1), 25.6 parts by weight (0.2 parts by mole) of 2,2-dimethylsuccinic anhydride, and 0.012 parts by weight (9.7 × 10 －５ The mixture was heated to 90°C with stirring while air was passed through, and the reaction was carried out at 90°C for 10 hours. １ The esterification reaction product was confirmed by H-NMR (yield: 98 mol%). Monomer (b-1) is a compound represented by general formula (2), and A in general formula (2) ２ is a methacryloyl group, -X ４ - is a group represented by -O-, -Y１ - is a group represented by general formula (4), Z １ is a residue obtained by removing one carboxy group from dimethylsuccinic acid, and R in general formula (4) ６ is an ethylene group, X ５ is a group represented by —O—, R ７ is a pentylene group, the molar average value of r is 3. The SP value is 10.59.

[0125] <Production Example 6> [Production of Monomer (b-2)] A reaction vessel equipped with a temperature controller, a stirring blade, a pressure reducing device, a Dimroth condenser, a fractionating column, a distillate receiving flask, and a nitrogen inlet and outlet was charged with 117.4 parts by weight (0.2 parts by mole) of monomer (a-2), 25.6 parts by weight (0.2 parts by mole) of 2,2-dimethylsuccinic anhydride, and 0.014 parts by weight (11.3 × 10) of hydroquinone monomethyl ether. －５ The mixture was heated to 90°C with stirring while air was passed through, and the reaction was carried out at 90°C for 10 hours. １ The esterification reaction product was confirmed by H-NMR (yield: 98 mol%). Monomer (b-2) is a compound represented by general formula (2), and A in general formula (2) ２ is a methacryloyl group, -X ４ - is a group represented by -O-, -Y １ - is a group represented by general formula (4), Z １ is a residue obtained by removing one carboxy group from dimethylsuccinic acid, and R in general formula (4) ６ is an ethylene group, X ５ is a group represented by —O—, R ７ is a pentylene group, the molar average value of r is 4. The SP value is 10.52.

[0126] (a'-1): 10 moles of ε-caprolactone adduct of HEA (SP value: 10.54) (b-3): Monoesterification reaction product of polyethylene glycol (2 moles) monomethacrylate (diethylene glycol monomethacrylate) and 2,2-dimethylsuccinic acid (SP value: 10.94) {a compound represented by general formula (2), A in general formula (2) ２ is a methacryloyl group, -X ４ - is a group represented by -O-, -Y １- is a group represented by formula (3), Z １ is a residue obtained by removing one carboxy group from dimethylsuccinic acid, and R in general formula (3) ４ and R ５ is an ethylene group, and q=1} (b-4): a monoesterification reaction product of HEMA and 2,2-dimethylsuccinic acid (SP value: 11.21) {a compound represented by general formula (2), where A in general formula (2) ２ is a methacryloyl group, -X ４ - is a group represented by -O-, -Y １ - is an ethylene group, Z １ is a residue obtained by removing one carboxy group from dimethylsuccinic acid} (b-5): a monoesterification reaction product of monomer (a-1) and trimellitic acid (SP value: 11.59) {a compound represented by general formula (2), ２ is a methacryloyl group, -X ４ - is a group represented by -O-, -Y １ - is a group represented by general formula (4), Z １ is a residue obtained by removing one carboxy group from trimellitic acid, and R in general formula (4) ６ is an ethylene group, X ５ is a group represented by —O—, R ７ is a pentylene group, and the molar average value of r is 3} (b-6): a monoesterification reaction product of monomer (a-2) and trimellitic acid (SP value: 11.36) {a compound represented by general formula (2), ２ is a methacryloyl group, -X ４ - is a group represented by -O-, -Y １ - is a group represented by general formula (4), Z １ is a residue obtained by removing one carboxy group from trimellitic acid, and R in general formula (4) ６ is an ethylene group, X ５ is a group represented by —O—, R ７ is a pentylene group, and the molar average value of r is 4} (b-7): phthalic acid monohydroxyethyl acrylate ("Aronix M-5400" manufactured by Toagosei Co., Ltd.) (SP value: 12.87) {a compound represented by general formula (2), ２ is an acryloyl group, -X４ - is a group represented by -O-, -Y １ - is an ethylene group, Z １ is a residue in which one carboxy group has been removed from phthalic acid.} (b'-1): Monoesterification reaction product of monomer (a-1) and succinic acid (SP value: 10.81) (c-1): Methacrylic acid ester of Neodol 23 (manufactured by Shell Chemicals, a mixture of linear or branched alkyl alcohols having 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-dodecylhexadecyl methacrylate (c-6): 2-tetradecyloctadecyl methacrylate (c-7): dodecyl acrylate (c-8): n-octadecyl acrylate (d-1): methyl methacrylate (d-2): butyl methacrylate (e-1): N,N-dimethylaminoethyl methacrylate (f-1): glycerin monomethacrylate (NOF Corporation, "Blenmer GLM") (f-2): 2-hydroxyethyl methacrylate (HEMA) (g-1): tetrahydrofurfuryl methacrylate (tetrahydrofurfuryl methacrylate) (h-1): ethylene glycol monoacetoacetate monomethacrylate

[0127]

[0128] Examples 1 to 38, Comparative Examples 1 to 4 A reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a nitrogen inlet tube was charged with 185 parts by weight of ethyl acetate, 100 parts by weight of a blend of various monomers shown in Tables 3-1 to 3-7, and dodecyl mercaptan and 2,2'-azobis(2-methylbutyronitrile) in the amounts shown in Tables 3-1 to 3-7 as initiators and chain transfer agents, respectively, and then purged with nitrogen (gas phase oxygen concentration: 100 ppm). The vessel was then heated to 76°C with stirring in a sealed container, and a polymerization reaction was carried out at the same temperature for 6 hours. Mineral oil [SP value: 8.3 (cal / cm ３ ) １／２ , kinematic viscosity at 100 ° C: 4.2 mm ２150 parts by weight of a copolymer of 1 / 2, viscosity index: 122 was added, and the mixture was heated to 90°C. After that, the unreacted monomer and ethyl acetate were removed at the same temperature under reduced pressure (0.027 to 0.040 MPa) over 2 hours to obtain anti-wear agents (A-1) to (A-38) of the present invention containing 40% by weight of the copolymer, and comparative anti-wear agents (B-1) to (B-4).

[0129]

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136] Examples 39 to 76, Comparative Examples 5 to 8 The obtained anti-wear agents (A-1) to (A-38) and comparative anti-wear agents (B-1) to (B-4) were mixed with a Toyota Motor Corporation genuine e-transaxle fluid TE (kinematic viscosity at 100°C: 3.30 mmHg) as a base oil. ２ / s) so that the copolymer content in the lubricating oil composition was 2 wt % (solids equivalent), to obtain lubricating oil compositions (V-1) to (V-38) and (W-1) to (W-4).

[0137] The gelling properties of each antiwear agent, and the long-term stability, antiwear properties, etc. of each lubricating oil composition were measured and evaluated using the following methods. The results are shown in Tables 3-1 to 3-7. Note that lubricating oil composition (W-3) had poor long-term stability, and turbidity and precipitates were observed during the performance evaluation, so it was not evaluated for anything other than long-term stability.

[0138] <Additive kinematic viscosity> The kinematic viscosity at 100°C and the kinematic viscosity at 40°C of each lubricating oil composition other than (W-3) were measured by the method described in JIS-K2283 (2000). The results are reported as additive kinematic viscosities (mm ２ / s) are shown in Tables 3-1 to 3-7.

[0139] <Viscosity Index> The viscosity index of each lubricating oil composition other than (W-3) was measured by the method described in JIS-K2283 (2000). The results are shown as viscosity index in Tables 3-1 to 3-7.

[0140] <Long-term stability> 30 g of lubricating oil compositions (V-1) to (V-38) and (W-1) to (W-4) were placed in a container (length x width x height = 45 mm x 45 mm x 80 mm) and stored at 25°C. After 10 days, the presence or absence of turbidity and precipitates was visually confirmed. Compared with the lubricating oil composition immediately after production, those that did not show turbidity or precipitates were rated as ◯ for long-term stability, and those that showed turbidity or precipitates were rated as ×. The results are shown in Tables 3-1 to 3-7.

[0141] <Gelling Properties> 30 g of each anti-wear agent other than (B-3) was placed in a container (length x width x height = 45 mm x 45 mm x 80 mm) and held in a constant temperature bath at 100°C for 135 hours. The container was then turned on its side, and the state of the anti-wear agent was visually confirmed. If the agent was flowing and no solids were found inside, it was considered that no gel had occurred and the gelling properties were rated as "good." If the agent was not flowing or solids were found inside, it was considered that gel had occurred and the gelling properties were rated as "bad." The results are shown in Tables 3-1 to 3-7.

[0142] <Anti-Wear Properties> Tests were conducted in accordance with ASTM D 2783, except for the test conditions below. Specifically, for each lubricating oil composition other than (W-3), a load of 500 N was applied using a high-speed four-ball tester, and the composition was rotated for 16 seconds to check for the presence or absence of seizure. If no seizure was observed, the load was increased by 20 N increments, and the load immediately before seizure occurred was recorded as the maximum non-seizure load (N). The results are shown in Tables 3-1 to 3-7. The higher the maximum non-seizure load, the less likely seizure is to occur and the more excellent the anti-wear effect. (Measurement Conditions) Equipment: Space Creation KRL & Four-Ball Tester Ball: Steel Balls for Four Ball Bearings, Size: 1 / 2 Speed: 1760 rpm Temperature: 25°C Test duration: 16 seconds Test start load: 500 N Load increase interval: 20 N

[0143] As is clear from the results in Tables 3-1 to 3-7, the antiwear agents of the present invention (Examples 1 to 38) are resistant to gelation even at high temperatures, and furthermore, are excellent in long-term stability (the antiwear agent is less likely to precipitate), making it possible to provide lubricating oil compositions (Examples 39 to 76) with high antiwear properties. On the other hand, the antiwear agents of Comparative Examples 1 to 4 are found to have inferior gelation properties compared to the antiwear agents of the present invention, or to significantly reduce at least one of the long-term stability and antiwear properties of the lubricating oil compositions (Comparative Examples 5 to 8).

[0144] The lubricating oil composition containing the antiwear agent of the present invention is suitable as a drive system lubricating oil (MTF, differential gear oil, ATF, belt-CVTF, etc.), hydraulic oil (machine hydraulic oil, power steering oil, shock absorber oil, etc.), engine oil (for gasoline and diesel engines, etc.) and traction oil, and is preferably useful as a transmission oil, electric motor oil, or dual-purpose oil for both transmissions and electric motors in electric vehicles or hybrid vehicles, and particularly preferably as a dual-purpose oil for both transmissions and electric motors in electric vehicles or hybrid vehicles.

Claims

1. An anti-wear agent containing a copolymer (A) having, as essential constituent monomers, a monomer (a) represented by the following general formula (1) and a monomer (b) represented by the following general formula (2) or (2'), wherein, in the monomers constituting the copolymer (A), the average value of p per mole of monomer (a) is 1 to 4. [In general formula (1), A １ represents a polymerizable unsaturated group having 2 to 5 carbon atoms; -X １ -, -X ２ - and -X ３ - each independently represents a group represented by -O- or -NH-; R １ is an alkylene group having 1 to 4 carbon atoms; R ２ is an alkylene group having 2 to 20 carbon atoms; p is an integer of 1 to 100, and when p is 2 or more, a plurality of R ２ and X ３ may be the same or different; R ３ represents a hydrogen atom, a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms, a phenyl group in which a 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 a hydrogen atom in the aromatic ring may be substituted with a linear or branched aliphatic hydrocarbon group having 1 to 44 carbon atoms.] [In the general formulas (2) and (2′), A ２ represents a polymerizable unsaturated group having 2 to 5 carbon atoms; -X ４ - is a group represented by -O- or -NH-; -Y １ - represents a divalent hydrocarbon group having 2 to 400 carbon atoms, some of the bonds of which may be substituted with at least one bond selected from the group consisting of -O-, -NH-, -C(=O)O-, -OC(=O)-, -C(=O)NH-, and -NHC(=O)-; Z １ represents a residue obtained by removing one carboxy group (X1) from a polycarboxylic acid (Z1), and the polycarboxylic acid (Z1) is a compound in which a hydrogen atom is not bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X2) other than the (X1); Z ２ represents a residue obtained by removing one hydroxy group from a hydroxy(poly)carboxylic acid (Z2), and the hydroxy(poly)carboxylic acid (Z2) is a compound in which no hydrogen atom is bonded to the carbon atom at the α-position relative to the carbonyl group in the carboxy group (X3) of (Z2).] 2. The anti-wear agent according to claim 1, wherein the weight ratio (a / b) of the monomer (a) to the monomer (b) constituting the copolymer (A) is 0.25 to 90.

3. -Y in the general formulas (2) and (2') １ The anti-wear agent according to claim 1, wherein -(R) is an alkylene group having 2 to 20 carbon atoms or a group represented by the following general formula (3), (4), or (5): ４ O) ｑ -R ５ - (3) [In general formula (3), R ４ O is an alkyleneoxy group having 2 to 4 carbon atoms, q is an integer from 1 to 20, and when q is 2 or more, there are a plurality of R ４ may be the same or different; R ５ is an alkylene group having 2 to 4 carbon atoms. ６ -(X ５ -C(=O)-R ７ ) ｒ - (4) [In general formula (4), R ６ represents an alkylene group having 1 to 4 carbon atoms; X ５ represents a group represented by —O— or —NH—, R ７ represents an alkylene group having 2 to 20 carbon atoms, r is an integer of 1 to 20, and when r is 2 or more, there are a plurality of R ７ and X ５ may be the same or different.] -(R ８ -C(=O)-X ６ ) ｓ -R ９ - (5) [In general formula (5), R ８ represents an alkylene group having 2 to 20 carbon atoms, and -X ６ - represents a group represented by -O- or -NH-, s is an integer of 1 to 20, and when s is 2 or more, there are a plurality of R ８ and X ６ may be the same or different, R ９ is an alkylene group having 2 to 20 carbon atoms.

4. The anti-wear agent according to claim 1, wherein the copolymer (A) contains, as a constituent monomer, a monomer (c) represented by the following general formula (6): [In general formula (6), R １０ is a hydrogen atom or a methyl group; -X ７ - is a group represented by -O- or -NH-; R １１ is a linear or branched alkyl group having 5 to 44 carbon atoms.

5. The anti-wear agent according to claim 4, wherein the total weight ratio of the monomers (a) and (b) constituting the copolymer (A) is 15 to 50% by weight based on the total weight of the constituent monomers of the copolymer (A), and the weight ratio of the monomer (c) is 50 to 85% by weight based on the total weight of the constituent monomers of the copolymer (A).

6. The anti-wear agent according to claim 1, wherein the monomer (b) is a compound represented by general formula (2), and the polycarboxylic acid (Z1) is at least one selected from the group consisting of phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, dimethylmalonic acid, 2,2-dimethylsuccinic acid, 2-ethyl-2-methylsuccinic acid, 2,2-dimethylglutaric acid, and 2,2-dimethyladipic acid.

7. The anti-wear agent according to claim 1, wherein the weight average molecular weight of said copolymer (A) is 5,000 to 500,000.

8. A lubricating oil composition comprising the antiwear agent according to any one of claims 1 to 7 and a base oil.

9. The kinematic viscosity of the base oil at 100°C is 1 to 4 mm ２ The lubricating oil composition according to claim 8, wherein 10. The lubricating oil composition according to claim 8, further comprising at least one selected from the group consisting of viscosity index improvers, detergents, dispersants, antioxidants, oiliness improvers, metal-based friction and wear modifiers, extreme pressure agents, antifoaming agents, demulsifiers, corrosion inhibitors, and pour point depressants.

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