Additive composition for lubricating oil and lubricating oil composition

Abstract

The present application provides a lubricating oil additive composition comprising a high molecular compound, which is excellent in solubility in mineral oil and wear resistance, is suitable as a friction modifier, and a lubricating oil composition containing the same. The problem is solved by producing a lubricating oil additive composition containing a copolymer (X) comprising structural units (a) to (c) below: structural unit (a): a structural unit derived from a monomer (A) having a (meth) acryloyl group and a linear or branched alkyl group having 6 or more and 24 or less carbon atoms structural unit (b): a structural unit derived from a monomer (B) having a (meth) acryloyl group and a polar group structural unit (c): a structural unit derived from a monomer (C) having a polymerizable functional group and a cyclic structural group The content of the above structural unit (a) is 43 mol% or more based on the total structural units of the copolymer (X), and the mass average molecular weight (Mw) of the copolymer (X) is 5,000 or more and 90,000 or less.

Description

Technical Field

[0001] This invention relates to additive compositions for lubricating oils and lubricating oil compositions containing the additive compositions for lubricating oils. Background Technology

[0002] Friction modifiers are a representative example of lubricant additives. Examples of widely used friction modifiers include phosphorus compounds such as phosphate esters, sulfur compounds such as sulfide olefins, and sulfur-phosphorus compounds such as thiophosphate esters.

[0003] However, phosphorus and sulfur are highly corrosive elements. Therefore, there is a need to create new load-bearing additives that do not contain phosphorus and sulfur. As such new friction modifiers, research has been conducted in recent years on polymeric compounds (see, for example, Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2012-041407 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, the wear resistance of polymeric compounds, as proposed in Patent Document 1, which only contain structural units derived from alkyl acrylates and hydroxyalkyl acrylates as structural units, is insufficient.

[0009] Furthermore, polymeric compounds sometimes exhibit turbidity when dissolved in mineral oils, which are commonly used as base oils for lubricants. When turbidity occurs, the insufficient solubility of the polymeric compound sometimes prevents it from fully realizing its intended function. Additionally, precipitation may sometimes occur at low temperatures. Therefore, polymeric compounds used as friction modifiers are required to have excellent solubility in mineral oils.

[0010] Therefore, the objective of this invention is to provide a lubricating oil additive composition containing a polymeric compound that exhibits excellent solubility and wear resistance in mineral oil and is suitable as a friction modifier, as well as a lubricating oil composition containing the lubricating oil additive composition.

[0011] Methods for solving problems

[0012] The inventors conducted in-depth research to solve the aforementioned problems. As a result, they discovered that copolymers containing structural units derived from specific monomers can solve these problems, thus completing the present invention.

[0013] That is, the present invention relates to the following [1] to [3].

[0014] [1] A composition for use as an additive in lubricating oil, comprising a copolymer (X) including the following structural units (a) to (c),

[0015] • Structural unit (a): A structural unit derived from a monomer (A) having a (meth)acryloyl group and a straight-chain or branched alkyl group having 6 or more carbon atoms and 24 or fewer carbon atoms.

[0016] • Structural unit (b): a structural unit derived from monomer (B) having a (meth)acryloyl group and a polar group.

[0017] • Structural unit (c): A structural unit derived from a monomer (C) having polymerizable functional groups and cyclic structural groups.

[0018] The content of the above-mentioned structural unit (a) is 43 mol% or more based on all structural units of the above-mentioned copolymer (X).

[0019] The mass-average molecular weight (Mw) of the copolymer (X) is 5,000 or more and 90,000 or less.

[0020] [2] A lubricating oil composition comprising the lubricating oil additive composition described in [1] above and a lubricating oil base oil.

[0021] [3] A manufacturing method for producing the lubricating oil additive composition described in [1] above.

[0022] The process (S) includes the polymerization of the monomers (A) to (C) to produce copolymer (X).

[0023] • Monomer (A): A monomer having a (meth)acryloyl group and a straight-chain or branched alkyl group having 6 or more but 24 or fewer carbon atoms.

[0024] • Monomer (B): A monomer having a (meth)acryloyl group and a polar group.

[0025] • Monomer (C): A monomer possessing polymerizable functional groups and cyclic structural groups.

[0026] Invention Effects

[0027] According to the present invention, it is possible to provide a lubricating oil additive composition containing a polymeric compound that has excellent solubility and wear resistance in mineral oil and is suitable as a friction modifier, as well as a lubricating oil composition containing the lubricating oil additive composition. Detailed Implementation

[0028] The upper and lower limits of the numerical ranges described in this specification can be combined arbitrarily. For example, when “A~B” and “C~D” are described as numerical ranges, the numerical ranges of “A~D” and “C~B” are also included within the scope of this invention.

[0029] In addition, unless otherwise specified, the numerical range “lower limit to upper limit” described in this specification refers to the value above the lower limit and below the upper limit.

[0030] In addition, the numerical values ​​in the embodiments described in this specification are values ​​that can be used as upper or lower limits.

[0031] In this specification, "(meth)acrylate" means acrylate or methacrylate, and other similar terms have the same meaning.

[0032] In this specification, "number of cyclic carbon atoms" refers to the number of carbon atoms in the atoms constituting the ring itself in a compound that has formed a cyclic structure by atomic bonds. When the ring is substituted with a substituent, the carbon atoms contained in the substituent are not included in the number of cyclic carbon atoms. The "number of cyclic carbon atoms" described below is the same unless otherwise stated. For example, the number of cyclic carbon atoms in a benzene ring is 6. Furthermore, when the benzene ring is substituted with, for example, an alkyl group, the number of carbon atoms in that alkyl group is not included in the number of cyclic carbon atoms in the benzene ring. Therefore, the number of cyclic carbon atoms in a benzene ring substituted with an alkyl group is 6.

[0033] In this specification, "number of cyclic atoms" refers to the number of atoms constituting the ring itself in a compound that has a cyclic structure formed by atomic bonds. Atoms that do not form a ring (e.g., hydrogen atoms that end the bonds of the atoms forming the ring) and atoms contained in substituents when the ring is substituted are not included in the number of cyclic atoms. The "number of cyclic atoms" described below is the same unless otherwise stated. For example, the number of cyclic atoms in a pyridine ring is 6. Furthermore, the number of hydrogen atoms bonded to the pyridine ring or the number of atoms constituting substituents are not included in the number of cyclic atoms in the pyridine ring. Therefore, the number of cyclic atoms in a pyridine ring bonded with hydrogen atoms or substituents is 6.

[0034] [Form of additive compositions for lubricating oils]

[0035] The lubricant additive composition of this embodiment contains copolymer (X).

[0036] The copolymer (X) comprises the following structural units (a) to (c).

[0037] • Structural unit (a): A structural unit derived from a monomer (A) having a (meth)acryloyl group and a straight-chain or branched alkyl group having 6 or more carbon atoms and 24 or fewer carbon atoms.

[0038] • Structural unit (b): a structural unit derived from monomer (B) having a (meth)acryloyl group and a polar group.

[0039] • Structural unit (c): A structural unit derived from a monomer (C) having polymerizable functional groups and cyclic structural groups.

[0040] Furthermore, the content of structural unit (a) in copolymer (X) is 43 mol% or more based on all structural units of copolymer (X), and the mass-average molecular weight (Mw) is 5,000 or more and 90,000 or less.

[0041] The inventors conducted in-depth research to solve the aforementioned problems. Their findings revealed that a copolymer (X) comprising structural units (a) derived from monomers (A) having a (meth)acryloyl group and a straight-chain or branched alkyl group having 6 or more and 24 carbon atoms, structural units (b) derived from monomers (B) having a (meth)acryloyl group and a polar group, and structural units (c) derived from monomers (C) having polymerizable functional groups and cyclic structural groups, with the content of structural unit (a) adjusted to the aforementioned range and the mass-average molecular weight (Mw) adjusted to the aforementioned range, exhibits excellent solubility and wear resistance in lubricating oil base oils.

[0042] The reasons for the excellent solubility and wear resistance of copolymer (X) in lubricating oil base oil are speculated as follows.

[0043] (1) Ensure appropriate oil solubility (solubility in mineral oil) by including a certain amount or more of the above structural unit (a).

[0044] (2) A copolymer that is multi-point adsorption type by including the above-mentioned structural unit (b).

[0045] (3) By including the above-mentioned structural unit (c), intermolecular interactions based on cyclic structural groups are generated. As a result, when the copolymer (X) is adsorbed on the surfaces of the two opposing components, a moderate repulsive force is generated between the components, resulting in a friction reduction effect.

[0046] (4) By adjusting the mass-average molecular weight (Mw) of copolymer (X) to a certain range, copolymer (X) becomes easier to enter between two opposing components, thus fully utilizing the friction reduction effect brought about by copolymer (X).

[0047] In this embodiment, the copolymer (X) may consist only of structural units (a) derived from monomer (A), structural units (b) derived from monomer (B), and structural units (c) derived from monomer (C). However, without impairing the effects of the present invention, it may also contain other structural units besides structural units (a), (b), and (c).

[0048] In this embodiment, the total content of structural units (a), (b), and (c) in the copolymer (X) is preferably 70 mol% to 100 mol% based on all structural units of the copolymer (X), more preferably 80 mol% to 100 mol%, and even more preferably 90 mol% to 100 mol%.

[0049] The monomers (A) to (C) will be described in detail below.

[0050] <Monotype (A), Structural Unit (a)>

[0051] The monomer (A) used in this embodiment has a (meth)acryloyl group and a straight-chain or branched alkyl group with 6 or more and 24 or fewer carbon atoms.

[0052] The structural unit (a) derived from monomer (A) mainly plays the role of oil solubility (solubility in mineral oil) in copolymer (X).

[0053] It should be noted that monomer (A) can be used alone or in combination with two or more monomers. Therefore, copolymer (X) can contain one structural unit (a) derived from monomer (A) alone or in combination with two or more monomers.

[0054] It should be noted that, in this specification, monomer (A) is not included in monomers (B) and (C). Therefore, structural unit (a) derived from monomer (A) is also not included in structural unit (b) derived from monomer (B) and structural unit (c) derived from monomer (C).

[0055] (Single unit (A1), Structural unit (a1))

[0056] In this embodiment, from the viewpoint of more easily achieving the effects of the present invention, the monomer (A) preferably comprises the monomer (A1) shown in the following general formula (a-1). That is, the structural unit (a) preferably comprises the structural unit (a1) derived from the monomer (A1).

[0057] [Chemical Formula 1]

[0058]

[0059] In the above general formula (a-1), R a1 It can be a hydrogen atom or a methyl group. That is, the monomer (A1) has an acryloyl group or a methacryloyl group as a polymerizable functional group.

[0060] R a1 Monomers with substituents other than hydrogen atoms and methyl groups are difficult to obtain, and these monomers have low reactivity, making them difficult to polymerize.

[0061] It should be noted that, from the perspective of easily further improving wear resistance, R a1 The preferred component is a hydrogen atom. That is, the polymerizable functional group of the monomer (A1) is preferably an acryloyl group.

[0062] In the above general formula (a-1), R a2 It refers to a straight-chain or branched alkyl group with 6 or more but less than 24 carbon atoms.

[0063] When the number of carbon atoms in the alkyl group is less than 6 or more than 24, it is difficult to ensure the oil solubility (solubility in mineral oil) of the copolymer (X).

[0064] As can be selected as R a2 Straight-chain alkyl groups with 6 or more carbon atoms and 24 or fewer, for example, n-hexyl, n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl, n-docodecyl and n-tetradecyl.

[0065] Examples of branched alkyl groups with 6 or more carbon atoms and 24 or fewer include isooctyl, tert-octyl, 2-ethylhexyl, isononyl, isodecyl, and isooctadecyl.

[0066] From the viewpoint that it is easier to ensure the oil solubility of the poly(meth)acrylate copolymer (X), the alkyl group preferably has 7 or more carbon atoms, more preferably 8 or more. Furthermore, it is preferably 22 or less, more preferably 20 or less.

[0067] The structural unit (a1) of a monomer (A1) can contain one type or more types.

[0068] It should be noted that, in this specification, monomer (A1) is not included in monomers (B) and (C). Therefore, structural unit (a1) derived from monomer (A1) is also not included in structural unit (b) derived from monomer (B) and structural unit (c) derived from monomer (C).

[0069] (Content of structural unit (a1))

[0070] In this embodiment, the content of structural unit (a1) is preferably 50 mol% to 100 mol% based on all structural units of structural unit (a), more preferably 60 mol% to 100 mol%, even more preferably 70 mol% to 100 mol%, even more preferably 80 mol% to 100 mol%, and even more preferably 90 mol% to 100 mol%.

[0071] <Monotype (B), Structural Unit (b)>

[0072] The monomer (B) used in this embodiment has (meth)acryloyl and polar groups.

[0073] It is speculated that the structural unit (b) derived from monomer (B) functions to make copolymer (X) a multi-point adsorption type copolymer, which is beneficial to improving wear resistance.

[0074] It should be noted that monomer (B) can be used alone or in combination with two or more monomers. Therefore, copolymer (X) can contain one structural unit (b) derived from monomer (B) alone or in combination with two or more monomers.

[0075] It should be noted that in this specification, monomer (B) is not included in monomers (A) and (C). Therefore, structural unit (b) derived from monomer (B) is also not included in structural unit (a) derived from monomer (A) and structural unit (c) derived from monomer (C).

[0076] (Single unit (B1), Structural unit (b1))

[0077] In this embodiment, from the viewpoint of more easily achieving the effects of the present invention (especially from the viewpoint of easily improving the solubility of copolymer (X) in mineral oil), monomer (B) preferably comprises monomer (B1) having one or more polar groups selected from nitrogen-containing groups, hydroxyl groups, and carboxyl groups. That is, structural unit (b) preferably comprises structural unit (b1) derived from monomer (B1) having (meth)acryloyl groups and these polar groups.

[0078] Monomers having (meth)acryloyl groups and nitrogen-containing groups

[0079] Examples of monomers having (meth)acryloyl groups and nitrogen-containing groups include amide-containing acrylic monomers, primary amino-containing acrylic monomers, secondary amino-containing acrylic monomers, tertiary amino-containing acrylic monomers, nitrile-containing acrylic monomers, urea-containing acrylic monomers, and urethane-containing acrylic monomers.

[0080] Examples of amide-containing acrylic monomers include (meth)acrylamide; monoalkylamino (meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-n-butyl(meth)acrylamide, and N-isobutyl(meth)acrylamide; and N-methylaminoethyl(meth)acrylamide, N-ethylaminoethyl(meth)acrylamide, N-isopropylaminon-butyl(meth)acrylamide, N-n-butylaminon-butyl(meth)acrylamide, and N-isobutylaminon-butyl(meth)acrylamide. Monoalkylaminoalkyl (methyl)acrylamides such as methacrylamide; dialkylamino (methyl)acrylamides such as N,N-dimethyl (methyl)acrylamide, N,N-diethyl (methyl)acrylamide, N,N-diisopropyl (methyl)acrylamide, and N,N-di-n-butyl (methyl)acrylamide; dialkylaminoalkyl (methyl)acrylamides such as N,N-dimethylaminoethyl (methyl)acrylamide, N,N-diethylaminoethyl (methyl)acrylamide, N,N-dimethylaminopropyl (methyl)acrylamide, and N,N-di-n-butylaminobutyl (methyl)acrylamide.

[0081] Examples of acrylic monomers containing primary amino groups include aminoethyl methacrylate and aminoalkyl methacrylates having alkyl groups with 2 to 6 carbon atoms.

[0082] Examples of acrylic monomers containing secondary amino groups include tert-butylaminoethyl methacrylate and methylaminoethyl methacrylate, as well as monoalkylaminoalkyl methacrylates.

[0083] Examples of acrylic monomers containing tertiary amino groups include dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, as well as dialkylaminoalkyl methacrylates.

[0084] Examples of acrylic monomers containing nitrile groups include (meth)acrylonitrile.

[0085] Examples of urea-containing acrylic monomers include ethyl (meth)acrylate and others.

[0086] Examples of acrylic monomers containing urethane groups include monofunctional urethane acrylates.

[0087] Monomers containing (meth)acryloyl and hydroxyl groups

[0088] Examples of monomers containing (meth)acryloyl and hydroxyl groups include hydroxyl-containing acrylic monomers.

[0089] Examples of hydroxyl-containing acrylic monomers include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 3-hydroxypropyl methacrylate, etc., which are hydroxyalkyl methacrylates; monohydroxyalkyl-substituted (meth)acrylamides or dihydroxyalkyl-substituted (meth)acrylamides, such as N,N-dihydroxymethyl (meth)acrylamide, N,N-dihydroxypropyl (meth)acrylamide, and N,N-di-2-hydroxybutyl (meth)acrylamide.

[0090] Monomers containing (meth)acryloyl and carboxyl groups

[0091] Examples of monomers containing (meth)acryloyl and carboxyl groups include, for example, acrylic monomers containing carboxyl groups.

[0092] Examples of acrylic monomers containing carboxyl groups include (meth)acrylic acid; carboxyethyl (meth)acrylic acid esters and other carboxyalkyl (meth)acrylic acid esters.

[0093] Preferred acrylic monomers

[0094] From the viewpoint that it is easier to achieve the effects of the present invention, the acrylic monomers mentioned above are preferably selected from one or more of dialkylaminoalkyl (meth)acrylamide, hydroxyalkyl (meth)acrylate, and carboxylalkyl (meth)acrylate.

[0095] It should be noted that the alkyl groups of these monomers preferably have 1 to 6 carbon atoms, more preferably 1 to 4.

[0096] The structural unit (b1) derived from the monomer (B1) can contain one type or more types.

[0097] It should be noted that, in this specification, monomer (B1) is not included in monomer (A) and monomer (C). Therefore, structural unit (b1) derived from monomer (B1) is also not included in structural unit (a) derived from monomer (A) and structural unit (c) derived from monomer (C).

[0098] (Content of structural unit (b 1))

[0099] In this embodiment, the content of structural unit (b1) is preferably 50 mol% to 100 mol% based on all structural units of structural unit (b), more preferably 60 mol% to 100 mol%, further preferably 70 mol% to 100 mol%, even more preferably 80 mol% to 100 mol%, and still more preferably 90 mol% to 100 mol%.

[0100] (Single unit (B2), Structural unit (b2))

[0101] In this embodiment, from the viewpoint of improving the oil solubility (solubility in mineral oil) of the copolymer (X), it is preferable to have a low content of structural units (b2) derived from monomers (B2) having polyoxyalkylene groups as polar groups.

[0102] Specifically, the content of structural unit (b2) derived from monomer (B2) having (meth)acryloyl and polyoxyalkylene groups is preferably less than 5 mol%, more preferably less than 1 mol%, further preferably less than 0.1 mol%, and most preferably does not contain structural unit (b2) based on all structural units of structural unit (b).

[0103] Examples of monomers (B2) having (meth)acryloyl and polyoxyalkylene groups include polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol monomethyl ether acrylate, lauryl ethylene oxide adduct (meth)acrylate, etc.

[0104] It should be noted that the number of carbon atoms in the alkylene chain of polyoxyalkylene is, for example, 2 or more and 4 or less, and the degree of polymerization is 2 or more (e.g., 2 to 50).

[0105] <Monomers with polymerizable functional groups and cyclic structural groups (C)>

[0106] The monomer (C) used in this invention has polymerizable functional groups and cyclic structural groups.

[0107] It is hypothesized that structural units (c) derived from monomer (C) function as friction-reducing agents in copolymer (X). Specifically, it is hypothesized that through intermolecular interactions based on the cyclic structural groups of structural unit (c), when copolymer (X) adsorbs onto the surfaces of two opposing components, a moderate repulsive force is generated between the components, thereby reducing friction.

[0108] It should be noted that monomer (C) can be used alone or in combination with two or more monomers. Therefore, copolymer (X) can contain one structural unit (c) derived from monomer (C) alone or in combination with two or more monomers.

[0109] It should be noted that, in this specification, monomer (C) is not included in monomers (A) and (B). Therefore, structural unit (c) derived from monomer (C) is also not included in structural unit (a) derived from monomer (A) and structural unit (b) derived from monomer (B).

[0110] As a polymerizable functional group of monomer (C), there are no particular limitations as long as it can form copolymer (X) with monomer (A) and monomer (B), and acryloyl, methacryloyl or vinyl are preferred examples.

[0111] It should be noted that, from the viewpoint of easily improving wear resistance, the polymerizable functional group is preferably acryloyl or methacryloyl, and more preferably acryloyl.

[0112] (Single unit (C1), Structural unit (c1))

[0113] In this embodiment, from the viewpoint of more easily achieving the effects of the present invention, the monomer (C) preferably contains a monomer (C1) having one or more cyclic structures selected from (I) to (III) below as cyclic structure groups.

[0114] (I) Aromatic rings with 6 or more but less than 14 carbon atoms

[0115] (II) Alicyclic rings with 3 or more but less than 14 carbon atoms

[0116] (III) A heterocycle containing 3 or more but less than 14 heteroatoms selected from nitrogen and oxygen atoms.

[0117] That is, the structural unit (c) preferably includes polymerizable functional groups and structural units (c1) derived from monomers (C1) having one or more ring structures selected from (I) to (III) below.

[0118] • (I) Aromatic rings with 6 or more but less than 14 carbon atoms

[0119] Examples of aromatic rings with 6 or more but less than 14 carbon atoms include benzene, naphthalene, anthracene, and phenanthrene.

[0120] It should be noted that, from the viewpoint of more easily achieving the effects of the present invention, the number of carbon atoms in the aromatic ring is preferably 6 or more and 10 or less. Specifically, the aromatic ring is preferably benzene.

[0121] (II) Alicyclic rings with 3 or more but less than 14 carbon atoms

[0122] Examples of alicyclic rings with 3 or more but less than 14 carbon atoms include monocyclic saturated alicyclic rings such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, and cyclododecane; monocyclic unsaturated alicyclic rings such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, and cyclododecene; polycyclic saturated alicyclic rings such as norbornane and adamantene; and polycyclic saturated alicyclic rings such as norbornene and adamantene.

[0123] It should be noted that, from the viewpoint of more easily achieving the effects of the present invention, the number of carbon atoms forming the alicyclic ring is preferably 5 or more and 14 or less, more preferably 5 or more and 10 or less.

[0124] Furthermore, from the viewpoint that it is easier to achieve the effects of the present invention, the alicyclic ring is preferably a saturated alicyclic ring with a monocyclic structure or an unsaturated alicyclic ring with a monocyclic structure, and more preferably a saturated alicyclic ring with a monocyclic structure.

[0125] Specifically, the alicyclic ring is preferably cyclohexane or cyclohexene, more preferably cyclohexane.

[0126] (III) A heterocycle containing 3 or more but less than 14 heteroatoms selected from nitrogen and oxygen atoms.

[0127] As a heterocycle containing one or more heteroatoms selected from nitrogen and oxygen atoms, having a cyclic carbon atom number of 3 or more and less, examples of monocyclic heterocycles include aziridine, ethylene oxide, diaziridine, oxapropidine, and dioxacyclopropane, etc., which are saturated 3-membered ring heterocycles; acrylidine, ethylene oxide, diapropidine, etc. Unsaturated 3-membered heterocycles such as aziridine, oxadiene, diazabutane, and dioxadiene; unsaturated 4-membered heterocycles such as aziridine, oxadiene, diazabutane, and dioxadiene; pyrrolidine, tetrahydrofuran, and imidazole; Saturated 5-membered heterocyclic rings such as pyrazolidine, oxazolidine, isoxazolidine, and dioxolane; unsaturated 5-membered heterocyclic rings such as pyrrole, furan, imidazole, pyrazole, oxazole, isoxazole, triazole, furazolidone, oxadiazole, dioxazole, tetrazolium, oxatetrazole, and pentaazole; saturated 6-membered heterocyclic rings such as piperidine, tetrahydropyran, piperazine, morpholine, dioxane, hexahydro-1,3,5-triazine, and trioxane; pyridine, tetrahydropyran, diazine, and oxazine. Unsaturated 6-membered heterocyclic rings such as dioxins, triazines, tetraazines, and pentaazines; saturated 7-membered heterocyclic rings such as azirheptan, oxepine, and diazirheptan; and unsaturated 7-membered heterocyclic rings such as azepine, oxepine, and diazirheptan.

[0128] Examples of heterocyclic compounds with polycyclic structures include 1H-pyrrolidine, indazine, isoindole, indole, indazole, purine, 4H-quinazine, isoquinoline, quinoline, phthalazine, naphthidine, quinoxaline, quinazoline, cyclophosphine, pteridine, carbazole, β-carboline, phenanthridine, acridine, perimidine, phenanthridine, phenazine, and phenoxazine.

[0129] It should be noted that, from the viewpoint of making it easier to achieve the effects of the present invention, the number of cyclic atoms in the heterocycle is preferably 5 or more and 14 or less, more preferably 5 or more and 10 or less.

[0130] · Substituents

[0131] The cyclic structures (I) to (III) above may be unsubstituted or may have substituents.

[0132] As a substituent, there is no particular limitation as long as it is within the scope of the effect of the present invention. For example, organic groups with 1 to 30 carbon atoms can be cited, and the organic group can have at least one of nitrogen atoms and oxygen atoms.

[0133] Specifically, examples include groups selected from alkyl groups having 1 to 30 carbon atoms (preferably 1 to 16, more preferably 1 to 8, and even more preferably 1 to 4), alkoxy groups having alkyl groups having 1 to 30 carbon atoms (preferably 1 to 16, more preferably 1 to 8, and even more preferably 1 to 4), amino groups, cyano groups, nitro groups, alkyl carbonyl groups having alkyl groups having 1 to 30 carbon atoms (preferably 1 to 16, more preferably 1 to 8, and even more preferably 1 to 4), hydroxyl groups, alkyl-substituted carbonyl groups, and carboxyl groups.

[0134] The substituents can be further replaced by any of the substituents mentioned above.

[0135] It should be noted that, from the viewpoint that it is easier to achieve the effects of the present invention, the ring structures in (I) to (III) above are preferably unsubstituted.

[0136] • Preferred method for monomer (C1)

[0137] From the viewpoint that it is easier to achieve the effects of the present invention, the monomer (C1) is preferably the monomer shown in the following general formula (c-1).

[0138] YLZ (c-1)

[0139] In the above general formula (c-1), Y represents a polymerizable functional group, L represents a direct bonding or linking group, and Z represents a cyclic structural group having the cyclic structures of (I) to (III) above.

[0140] Examples of polymerizable functional groups that can be selected as Y include acryloyl, methacryl, or vinyl. It should be noted that, from the viewpoint of easily further improving wear resistance, the polymerizable functional group is preferably acryloyl.

[0141] Examples of linking groups that can be selected as L include divalent aliphatic hydrocarbon groups with 1 to 4 carbon atoms, such as methylene, ethylene, n-propylene, and n-butylene; divalent groups with 6 to 10 carbon atoms having a cyclic structure, such as phenyl ethylene and phenylene; -O-; oxoalkylene (preferably with 1 to 4 carbon atoms); polyoxoalkylene (preferably with 1 to 4 carbon atoms), etc.

[0142] As a cyclic structure group that can be selected as Z, examples include monovalent cyclic structure groups obtained by removing one hydrogen atom from any of the cyclic structures (I) to (III) above. It should be noted that, from the viewpoint of easily further improving wear resistance, the cyclic structure group is preferably a monovalent cyclic structure group obtained by removing one hydrogen atom from the cyclic structure (I) or (II) above.

[0143] In (I) above, the aromatic ring having 6 or more but less than 10 carbon atoms is preferred.

[0144] In (II) above, a saturated alicyclic ring with a monocyclic structure or an unsaturated alicyclic ring with a monocyclic structure is preferred, and a saturated alicyclic ring with a monocyclic structure is more preferred. The number of carbon atoms in the ring is preferably 6 or more and 10 or less.

[0145] Examples of preferred compounds as monomers (C1) include benzyl acrylate, cyclohexyl acrylate, and styrene.

[0146] The structural unit (c1) derived from the monomer (C1) can contain one type or more types.

[0147] For example, the structural unit (c1) derived from the monomer (C1) may comprise two or more structural units derived from two or more monomers with different cyclic structural groups. Specifically, it may comprise structural units derived from a monomer having the cyclic structural group described above (I) and structural units derived from a monomer having the cyclic structural group described above (II); it may comprise structural units derived from a monomer having the cyclic structural group described above (I) and structural units derived from a monomer having the cyclic structural group described above (III); it may comprise structural units derived from a monomer having the cyclic structural group described above (II) and structural units derived from a monomer having the cyclic structural group described above (III); it may comprise structural units derived from a monomer having the cyclic structural group described above (I), structural units derived from a monomer having the cyclic structural group described above (II), and structural units derived from a monomer having the cyclic structural group described above (III).

[0148] It should be noted that, in this specification, monomer (C1) is not included in monomer (A) and monomer (B). Therefore, structural unit (c1) derived from monomer (C1) is also not included in structural unit (a) derived from monomer (A) and structural unit (b) derived from monomer (B).

[0149] (Content of structural unit (c1))

[0150] In this embodiment, the content of structural unit (c1) is preferably 50 mol% to 100 mol% based on all structural units of structural unit (c), more preferably 60 mol% to 100 mol%, further preferably 70 mol% to 100 mol%, even more preferably 80 mol% to 100 mol%, and even more preferably 90 mol% to 100 mol%.

[0151] <Content of structural unit (a)>

[0152] In this embodiment, the content of structural unit (a) from monomer (A) needs to be 43 mol% or more based on all structural units of copolymer (X).

[0153] If the content of structural unit (a) is less than 43 mol%, the copolymer (X) may not be able to achieve sufficient solubility in mineral oil.

[0154] It should be noted that, from the viewpoint of more easily exerting the effects of the present invention, the content of structural unit (a) from monomer (A) is preferably 50 mol% or more, more preferably 55 mol% or more, based on all structural units of copolymer (X).

[0155] Furthermore, from the viewpoint that achieving a balance in the content of each structural unit by ensuring the content of structural units (b) from monomer (B) and structural units (c) from monomer (C) makes it easier to exert the effects of the present invention, the content of structural unit (a) from monomer (A), based on all structural units of copolymer (X), is preferably 84 mol% or less, more preferably 80 mol% or less, and even more preferably 76 mol% or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, it is preferably 50 mol% to 84 mol%, more preferably 50 mol% to 80 mol%, and even more preferably 55 mol% to 76 mol%.

[0156] It should be noted that, in this specification, the proportion of each structural unit in the copolymer (X) is generally consistent with the ratio (feed ratio) of each monomer constituting the copolymer (X).

[0157] <Content of structural unit (b)>

[0158] In this embodiment, from the viewpoint of more easily exerting the effects of the present invention, the content of structural unit (b) from monomer (B) based on all structural units of copolymer (X) is preferably 9 mol% or more, more preferably 10 mol% or more, and even more preferably 12 mol% or more.

[0159] Furthermore, from the viewpoint that achieving a balance in the content of each structural unit by ensuring the content of structural units (a) from monomer (A) and structural units (c) from monomer (C) makes it easier to exert the effects of the present invention, the content of structural unit (b) from monomer (B), based on all structural units of copolymer (X), is preferably 50 mol% or less, more preferably 40 mol% or less, further preferably 30 mol% or less, and even more preferably 25 mol% or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, it is preferably 9 mol% to 50 mol%, more preferably 10 mol% to 40 mol%, and even more preferably 12 mol% to 30 mol%.

[0160] <Content of structural unit (c)>

[0161] In this embodiment, from the viewpoint of more easily exerting the effects of the present invention, the content of structural unit (c) from monomer (C) based on all structural units of copolymer (X) is preferably 7 mol% or more, more preferably 8 mol% or more, and even more preferably 10 mol% or more.

[0162] Furthermore, from the viewpoint that achieving a balance in the content of each structural unit by ensuring the content of structural units (a) from monomer (A) and structural units (b) from monomer (B) makes it easier to exert the effects of the present invention, the content of structural units (c) from monomer (C) is preferably 30 mol% or less, more preferably 28 mol% or less, further preferably 26 mol% or less, and even more preferably 25 mol% or less, based on all structural units of the copolymer (X). The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, it is preferably 7 mol% to 30 mol%, more preferably 8 mol% to 28 mol%, further preferably 10 mol% to 26 mol%, and even more preferably 10 mol% to 25 mol%.

[0163] <Containment ratio of each structural unit>

[0164] (The ratio of structural unit (b) to structural unit (a))

[0165] In the copolymer (X) of this embodiment, from the viewpoint of more easily exerting the effects of the present invention, the molar ratio of structural unit (b) to structural unit (a) [(b) / (a)] is preferably 0.15 or more, more preferably 0.20 or more, further preferably 0.25 or more, and even more preferably 0.30 or more. Additionally, it is preferably 0.50 or less, more preferably 0.45 or less, and even more preferably 0.40 or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, it is preferably 0.15 to 0.50, more preferably 0.20 to 0.45, further preferably 0.25 to 0.40, and even more preferably 0.30 to 0.40.

[0166] (Ratio of structural unit (c) to structural unit (a))

[0167] In the copolymer (X) of this embodiment, from the viewpoint of more easily exerting the effects of the present invention, the molar ratio of structural unit (c) to structural unit (a) [(c) / (a)] is preferably 0.10 or more, more preferably 0.20 or more, further preferably 0.30 or more, and even more preferably 0.40 or more. Additionally, it is preferably 0.48 or less, more preferably 0.46 or less, and even more preferably 0.45 or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, it is preferably 0.10 to 0.48, more preferably 0.20 to 0.46, further preferably 0.30 to 0.45, and even more preferably 0.40 to 0.45.

[0168] <Other Individuals>

[0169] In addition to the structural units (a), (b), and (c) described above, copolymer (X) may also contain structural units derived from other monomers, to the extent that it does not impair the effects of the present invention. Examples of such other monomers include functionalized monomers other than monomers (A), (B), and (C). Examples of such functionalized monomers include (meth)acrylates other than monomers (A), (B), and (C).

[0170] From the viewpoint that it is easier to achieve the effects of the present invention, the content of structural units of functionalized monomers other than monomers (A), (B) and (C) in copolymer (X) is preferably less than 30 mol%, more preferably less than 20 mol%, further preferably less than 10 mol%, even more preferably less than 1 mol%, and still more preferably less than 0.1 mol%.

[0171] Properties and polymerization methods of copolymer (X)

[0172] (weight-average molecular weight (Mw), molecular weight distribution (Mw / Mn))

[0173] The copolymer (X) in this embodiment needs to have a mass-average molecular weight (Mw) of 5,000 or more and 90,000 or less.

[0174] If the mass-average molecular weight (Mw) of the copolymer (X) is less than 5000, it is difficult to improve the wear resistance.

[0175] Furthermore, if the mass-average molecular weight (Mw) of copolymer (X) exceeds 90,000, its solubility in mineral oil is sometimes poor. Additionally, copolymer (X) has difficulty penetrating the gap between two components, thus hindering its ability to improve wear resistance.

[0176] From the viewpoint of more easily achieving the effects of the present invention and more easily improving solubility in lubricating oil base oils, a concentration of 5500 or more is preferred, more preferably 6000 or more, and even more preferably 7000 or more. Furthermore, a concentration of 80000 or less is preferred, more preferably 60000 or less, and even more preferably 50000 or less.

[0177] The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 5500 to 80000, more preferably 6000 to 60000, and even more preferably 7000 to 50000.

[0178] Furthermore, from the viewpoint of more easily achieving a friction-reducing effect, the molecular weight distribution (Mw / Mn) of the copolymer (X) in this embodiment is preferably 3.5 or less, more preferably 3.0 or less, and even more preferably 2.8 or less. It should be noted that the molecular weight distribution (Mw / Mn) of the copolymer (X) in this embodiment can be 1.01 or more, 1.3 or more, or 1.5 or more.

[0179] The mass-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) are values ​​determined or calculated using the methods described in the examples below.

[0180] (Aggregation Method)

[0181] The polymerization method of the copolymer (X) in this embodiment is not particularly limited, and can be any of block copolymerization, random copolymerization, or block / random copolymerization.

[0182] [Method for manufacturing additive compositions for lubricating oils]

[0183] The method for manufacturing the lubricating oil additive composition of this embodiment includes a step (S) of polymerizing the following monomers (A) to (C) to manufacture a copolymer (X).

[0184] • Monomer (A): A monomer having a (meth)acryloyl group and a straight-chain or branched alkyl group having 6 or more but 24 or fewer carbon atoms.

[0185] • Monomer (B): A monomer having a (meth)acryloyl group and a polar group.

[0186] • Monomer (C): A monomer possessing polymerizable functional groups and cyclic structural groups.

[0187] The following describes in detail the process (S) for manufacturing copolymer (X).

[0188] <Process (S) for manufacturing copolymer (X)>

[0189] The method for manufacturing copolymer (X) (polymerization method) is not particularly limited, and any known method can be used. Examples of such methods include emulsion polymerization, suspension polymerization, and solution polymerization.

[0190] From the viewpoint of the use of copolymer (X) in this invention, that is, its use as an additive composition for lubricating oil, the preferred method for manufacturing copolymer (X) is solution polymerization, which uses a solvent soluble in lubricating oil base oil as the solvent.

[0191] (Solution polymerization)

[0192] Solution polymerization is carried out, for example, by introducing monomers (A), (B), and (C), along with a solvent and an initiator, into a reactor, purging the reactor with nitrogen, and then stirring at 60°C to 100°C for 2 to 10 hours to allow the reaction to proceed. Optional monomers other than monomers (A), (B), and (C) may also be introduced into the reactor.

[0193] There are no particular limitations on the solvents used in solution polymerization, but esters such as polyol esters, diesters, hindered esters, and monoesters are preferred.

[0194] These can be used individually or in combination of two or more.

[0195] Examples of initiators used in solution polymerization include azo initiators such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-amidinylpropane) dihydrochloride, 2,2'-azobis-(N,N-dimethyleneisobutylamidinium) dihydrochloride, 1,1'-azobis(cyclohexyl-1-carboxynitrile), and 2,2'-azobis(2,4-dimethylpentanitrile); hydrogen peroxide; organic peroxides such as benzoyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, methyl ethyl ketone peroxide, and perbenzoic acid; persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; and hydrogen peroxide-Fe 2+Redox initiators; other existing free radical initiators.

[0196] Chain transfer agents used in solution polymerization include, for example, thiocarboxylic acids, secondary alcohols such as isopropanol, amines such as dibutylamine, hypophosphites such as sodium hypophosphite, chlorinated compounds, and alkylbenzene compounds.

[0197] It should be noted that the molecular weight of copolymer (X) can be controlled by known methods. For example, the molecular weight of copolymer (X) can be controlled by the reaction temperature, reaction time, amount of initiator, amount of each monomer added, type of solvent, and use of chain transfer agent.

[0198] (Input amount of monomer (A))

[0199] In the manufacturing method of this embodiment, from the viewpoint of easily adjusting the content of the above-described structural unit (a), the amount of monomer (A) added, based on all the monomers added, is preferably 57% by mass or more, 65% by mass or more, and more preferably 70% by mass or more. Furthermore, it is preferably 90% by mass or less, more preferably 87% by mass or less, and even more preferably 85% by mass or less.

[0200] The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the preferred values ​​are 57% to 90% by mass, 65% to 87% by mass, and more preferably 70% to 85% by mass.

[0201] It should be noted that the preferred compound as monomer (A) is as described above.

[0202] (Input amount of monomer (B))

[0203] In the manufacturing method of this embodiment, from the viewpoint that the content of the above-described structural unit (b) can be easily adjusted, the amount of monomer (B) added is preferably 5% by mass or more, more preferably 6% by mass or more, and even more preferably 7% by mass or more, based on all the monomers added.

[0204] Furthermore, the content is preferably 38% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 15% by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, it is preferably 5% by mass to 38% by mass, more preferably 6% by mass to 20% by mass, and even more preferably 7% by mass to 15% by mass.

[0205] It should be noted that the preferred compound as monomer (B) is as described above.

[0206] (Input amount of monomer (C))

[0207] In the manufacturing method of this embodiment, from the viewpoint that the content of the above-mentioned structural unit (c) can be easily adjusted, the amount of monomer (C) added is preferably 5% by mass or more, more preferably 6% by mass or more, and even more preferably 7% by mass or more, based on all the monomers added.

[0208] Furthermore, it is preferably 27% by mass or less, more preferably 23% by mass or less, and even more preferably 20% by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, it is preferably 5% by mass to 27% by mass, more preferably 6% by mass to 23% by mass, and even more preferably 7% by mass to 20% by mass.

[0209] It should be noted that the preferred compound as monomer (C) is as described above.

[0210] <Content of copolymer (X) in lubricating oil additive compositions>

[0211] From the viewpoint that the effects of the present invention are more easily achieved when added to a lubricating oil base oil, the content of copolymer (X) based on the total amount of the lubricating oil additive composition is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more. Furthermore, considering the purity of copolymer (X), the content of copolymer (X) is generally less than 99% by mass based on the total amount of the lubricating oil additive composition.

[0212] It should be noted that, from an operational point of view, the lubricant additive composition of this embodiment can be diluted using a diluent. It should also be noted that the content of copolymer (X) in the lubricant additive composition refers to the content relative to the total amount of active ingredients in the lubricant additive composition excluding the diluent.

[0213] As a diluent, it is preferable to use the same solvent as the polymerization solvent described above.

[0214] <Uses of Additive Compositions for Lubricating Oils>

[0215] The lubricating oil additive composition of this embodiment exhibits excellent solubility and wear resistance in lubricating oil base oils. Therefore, it is useful as a friction modifier.

[0216] Therefore, in this embodiment, a method of using the lubricating oil additive composition as a friction modifier is provided.

[0217] [Lubricating oil composition]

[0218] The lubricating oil composition of this embodiment contains a lubricating oil additive composition and a lubricating oil base oil, wherein the lubricating oil additive composition contains a copolymer (X).

[0219] Regarding the content of the additive composition for lubricating oil, from the viewpoint of maximizing the additive effect of the additive composition for lubricating oil, the content of copolymer (X) is preferably adjusted to 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, based on the total amount of the lubricating oil composition. Furthermore, the content of copolymer (X) is preferably adjusted to 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, based on the total amount of the lubricating oil composition.

[0220] The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, it is preferably 0.1% to 10% by mass, more preferably 0.2% to 5% by mass, and even more preferably 0.3% to 3% by mass.

[0221] <Lubricating Oil Base Oil>

[0222] The base oil for lubricating oils may be any commonly used base oils in lubricating oil compositions without particular limitation. Specifically, for example, one or more selected from mineral oils and synthetic oils may be cited.

[0223] The kinematic viscosity of the lubricating oil base oil at 100°C is preferably 1 mm. 2 / s~50mm 2 The range of / s is more preferably within 2mm. 2 / s~30mm 2 The range of / s is further preferably within 3mm. 2 / s~20mm 2 The viscosity index of the lubricating oil base oil is preferably 80 or higher, more preferably 90 or higher, and even more preferably 100 or higher.

[0224] The kinematic viscosity and viscosity index of lubricating oil base oil are values ​​determined or calculated according to JIS K2283:2000.

[0225] The following are specific examples of lubricating oil base oils.

[0226] Examples of mineral oils include distillates obtained by atmospheric distillation and / or vacuum distillation of paraffinic crude oil, intermediate-based crude oil, or naphthenic crude oil; and refined oils obtained by refining the distillates using conventional methods. Examples of refining methods for obtaining refined oils include solvent dewaxing, hydroisomerization, hydrorefining, and clay treatment.

[0227] Examples of synthetic oils include hydrocarbon oils, aromatic oils, ester oils, and ether oils. Additionally, GTL (Gas To Liquids) can be obtained by altering the properties of waxes (GTL waxes, Gas To Liquids Wax) produced from natural gas using the Fischer-Tropsch process or similar methods.

[0228] <Other Additives>

[0229] The lubricating oil composition of this embodiment may contain antioxidants, oiliness agents, detergents and dispersants, viscosity index improvers, rust inhibitors, metal passivators, and defoamers, etc., within a range that does not impair the effects of the above-described lubricating oil additive compositions. These additives may be used individually or in combination of two or more.

[0230] In addition, in this embodiment, an additive package is provided for a lubricating oil composition containing a lubricating oil additive composition comprising copolymer (X) and containing one or more additives selected from antioxidants, oiliness agents, detergents and dispersants, viscosity index improvers, rust inhibitors, metal passivators and defoamers as other additives besides the lubricating oil additive composition containing copolymer (X).

[0231] (Antioxidants)

[0232] As antioxidants, amine-based antioxidants, phenolic antioxidants, and other antioxidants commonly used in conventional lubricant compositions can be used. These antioxidants can be used alone or in combination of two or more.

[0233] Examples of amine-based antioxidants include monoalkyl diphenylamine compounds such as monooctyl diphenylamine and monononyl diphenylamine; dialkyl diphenylamine compounds such as 4,4'-dibutyl diphenylamine, 4,4'-dipentyl diphenylamine, 4,4'-dihexyl diphenylamine, 4,4'-diheptyl diphenylamine, 4,4'-dioctyl diphenylamine and 4,4'-dinonyl diphenylamine; polyalkyl diphenylamine compounds such as tetrabutyl diphenylamine, tetrahexyl diphenylamine, tetraoctyl diphenylamine and tetranonyl diphenylamine; and naphthylamine compounds such as α-naphthylamine, phenyl-α-naphthylamine, butylphenyl-α-naphthylamine, pentylphenyl-α-naphthylamine, hexylphenyl-α-naphthylamine, heptylphenyl-α-naphthylamine, octylphenyl-α-naphthylamine and nonylphenyl-α-naphthylamine.

[0234] Examples of phenolic antioxidants include monophenolic compounds such as 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butyl-4-ethylphenol; and bisphenolic compounds such as 4,4'-methylenebis(2,6-di-tert-butylphenol) and 2,2'-methylenebis(4-ethyl-6-tert-butylphenol).

[0235] The antioxidant content should be only the minimum amount required to maintain the oxidative stability of the lubricating oil composition. Specifically, for example, it is preferably 0.01 to 1% by mass based on the total amount of the lubricating oil composition.

[0236] (Oil-based agent)

[0237] Examples of oil-reducing agents include aliphatic alcohols; fatty acid compounds such as fatty acids and fatty acid metal salts; ester compounds such as polyol esters, sorbitol esters and glycerides; and amine compounds such as aliphatic amines.

[0238] From the perspective of additive effect, the content of oiliness agent is generally 0.1 to 20% by mass based on the total amount of the lubricating oil composition, preferably 0.5 to 10% by mass.

[0239] (Detergent Dispersant)

[0240] Examples of cleaning and dispersing agents include metal sulfonates, metal salicylates, metal phenolates, and succinimides.

[0241] From the viewpoint of additive effect, the content of detergent-dispersant is generally 0.01 to 10% by mass based on the total amount of the lubricating oil composition, preferably 0.1 to 5% by mass.

[0242] (Viscosity index improver)

[0243] Examples of viscosity index improvers include polymethyl methacrylate, dispersed polymethyl methacrylate, olefin copolymers (e.g., ethylene-propylene copolymers), dispersed olefin copolymers, and styrene copolymers (e.g., styrene-diene hydrogenated copolymers).

[0244] The content of the viscosity index improver is preferably 0.3 to 5% by mass, based on the total amount of the lubricating oil composition.

[0245] (Rust inhibitor)

[0246] Examples of rust inhibitors include metal sulfonates, succinates, and alkanolamines such as alkylamines and monoisopropanolamines.

[0247] From the perspective of additive effect, the content of rust inhibitor is generally 0.01 to 5% by mass based on the total amount of the lubricating oil composition, preferably 0.03 to 3% by mass.

[0248] (Metal passivating agent)

[0249] Examples of metal passivating agents include benzotriazole and thiadiazole.

[0250] From the viewpoint of additive effect, the preferred content of metal passivator, based on the total amount of the lubricating oil composition, is generally 0.01 to 5% by mass, preferably 0.01 to 1% by mass.

[0251] (Defoamer)

[0252] Examples of defoamers include methyl silicone oil, fluorosilicone oil, and polyacrylate.

[0253] From the perspective of additive effect, the content of defoamer is usually 0.0005 to 0.01% by mass, based on the total amount of the lubricating oil composition.

[0254] <Lubricating Grease Composition>

[0255] The lubricating oil additive composition of this embodiment can also be used in conjunction with a lubricating grease composition.

[0256] That is, in this embodiment, a grease composition containing the above-mentioned lubricating oil additive composition, thickener and lubricating oil base oil can also be provided.

[0257] <Physical properties of lubricating oil compositions, etc.>

[0258] (Kinematic viscosity, viscosity index)

[0259] The kinematic viscosity of the lubricating oil composition in this embodiment at 100°C is preferably 1.0 mm. 2 / s~50mm 2 / s, more preferably 2.0mm 2 / s~30mm 2 / s, further preferably 3.0mm 2 / s~20mm 2 / s.

[0260] The viscosity index of the lubricating oil composition in this embodiment is preferably 90 or higher, more preferably 100 or higher, and even more preferably 110 or higher.

[0261] The kinematic viscosity and viscosity index of the lubricating oil composition are values ​​determined or calculated according to JIS K2283:2000.

[0262] (Abrasion resistance)

[0263] The wear track diameter of the lubricating oil composition of this embodiment, as obtained from the ball-and-disc test described in the examples below, is preferably less than 520 μm, more preferably less than 500 μm, even more preferably less than 480 μm, even more preferably less than 460 μm, and even more preferably less than 440 μm.

[0264] [Uses of Lubricating Oil Compositions]

[0265] Because the lubricating oil composition of this embodiment contains copolymer (X), it has excellent wear resistance.

[0266] Therefore, the lubricating oil composition of this embodiment can be suitably used for various applications, such as drive system oils (gear oil, manual transmission oil, differential oil, etc.), automatic transmission oil (automatic transmission oil, etc.), continuously variable transmission oil (belt CVT oil, ring CVT oil, etc.), power steering oil, shock absorber oil, and electric motor oil; internal combustion engine (engine) oils for gasoline engines, diesel engines, and gas engines; hydraulic working oils; turbine oils; compressor oils; fluid bearing oils; rolling bearing oils; refrigeration oils, etc., and can be suitably used as a lubricating oil composition to be filled into devices used in these various applications to lubricate the various components of the device.

[0267] [Lubrication methods using lubricating oil compositions]

[0268] As a lubrication method using the lubricating oil composition of this embodiment, a preferred method is to fill the above-described lubricating oil composition into the apparatus used in the above-described applications and lubricate the components involved in the apparatus.

[0269] [One aspect of the present invention provided]

[0270] According to one aspect of the present invention, the following [1] to

[12] are provided.

[0271] [1] A composition for use as an additive in lubricating oil, comprising a copolymer (X) including the following structural units (a) to (c),

[0272] • Structural unit (a): A structural unit derived from a monomer (A) having a (meth)acryloyl group and a straight-chain or branched alkyl group having 6 or more carbon atoms and 24 or fewer carbon atoms.

[0273] • Structural unit (b): a structural unit derived from monomer (B) having a (meth)acryloyl group and a polar group.

[0274] • Structural unit (c): A structural unit derived from a monomer (C) having polymerizable functional groups and cyclic structural groups.

[0275] The content of the above-mentioned structural unit (a) is 43 mol% or more based on all structural units of the above-mentioned copolymer (X).

[0276] The mass-average molecular weight (Mw) of the copolymer (X) is 5,000 or more and 90,000 or less.

[0277] [2] The additive composition for lubricating oil according to [1] above, wherein the above structural unit (a) comprises a structural unit (a1) derived from a monomer (A1) represented by the following general formula (a-1).

[0278] [Chemical Formula 2]

[0279]

[0280] In the above general formula (a-1), R a1 Represents a hydrogen atom or a methyl group. R a2 This refers to a straight-chain or branched alkyl group with 6 or more but less than 24 carbon atoms.

[0281] [3] According to the above [1] or [2], the above structural unit (b) comprises a structural unit (b1) derived from a monomer (B1) having one or more groups selected from nitrogen-containing groups, hydroxyl groups and carboxyl groups as the above polar groups.

[0282] [4] The lubricating oil additive composition according to any one of [1] to [3] above, wherein, based on all the structural units of the above structural unit (b), the content of structural unit (b2) derived from the monomer (B2) having a polyoxyalkylene group as the above polar group is less than 5 mol%.

[0283] [5] The lubricating oil additive composition according to any one of [1] to [4] above, wherein the monomer (C) has a polymerizable functional group of (meth)acryloyl or vinyl.

[0284] [6] The lubricating oil additive composition according to any one of [1] to [5] above, wherein the structural unit (c) comprises a structural unit (c1) derived from a monomer (C1) having one or more cyclic structures selected from (I) to (III) below as cyclic structure groups.

[0285] (I) Aromatic rings with 6 or more but less than 14 carbon atoms

[0286] (II) Alicyclic rings with 3 or more but less than 14 carbon atoms

[0287] (III) A heterocycle containing 3 or more but less than 14 heteroatoms selected from nitrogen and oxygen atoms.

[0288] [7] The lubricating oil additive composition according to any one of [1] to [6] above, wherein the content of the above-mentioned structural unit (b) from the above-mentioned monomer (B) is 9 mol% or more based on all structural units of the above-mentioned copolymer (X).

[0289] [8] The lubricating oil additive composition according to any one of [1] to [7] above, wherein the content of the above-mentioned structural unit (c) from the above-mentioned monomer (C) is 7 mol% or more and 30 mol% or less based on all structural units of the above-mentioned copolymer (X).

[0290] [9] The lubricating oil additive composition according to any one of [1] to [8] above is used as a friction modifier.

[0291]

[10] A method of use, wherein the lubricating oil additive composition described in any one of [1] to [8] above is used as a friction modifier.

[0292]

[11] A lubricating oil composition comprising the lubricating oil additive composition described in any one of [1] to [9] above and a lubricating oil base oil.

[0293]

[12] A manufacturing method for producing the lubricating oil additive composition described in [1] above.

[0294] The process (S) includes the polymerization of the monomers (A) to (C) to produce copolymer (X).

[0295] • Monomer (A): A monomer having a (meth)acryloyl group and a straight-chain or branched alkyl group having 6 or more but 24 or fewer carbon atoms.

[0296] • Monomer (B): A monomer having a (meth)acryloyl group and a polar group.

[0297] • Monomer (C): A monomer possessing polymerizable functional groups and cyclic structural groups.

[0298] Example

[0299] The present invention will be specifically described through the following embodiments, but the present invention is not limited to the following embodiments.

[0300] [Methods for determining various physical properties]

[0301] The determination of the properties of each raw material used in each embodiment and each comparative example, as well as the properties of each lubricating oil composition in each embodiment and each comparative example, was carried out according to the following procedures.

[0302] (1) Kinematic viscosity, viscosity index

[0303] The kinematic viscosity and viscosity index of the base oil and lubricating oil composition at 100°C were determined or calculated according to JIS K2283:2000.

[0304] (2) Mass-average molecular weight (Mw), molecular weight distribution (Mw / Mn)

[0305] On a Waters HPLC pump (1515 isocratic) and detector (2414 differential refractive index (RI)), one TSK Guardcolumn SuperHZ-L column and two TSK SuperMultipore HZ-M columns were installed sequentially from the upstream side. The determination was performed at a temperature of 40°C, a mobile phase of tetrahydrofuran, a flow rate of 0.35 mL / min, and a sample concentration of 1.0 mg / mL. The results were obtained by conversion using standard polystyrene.

[0306] [Manufacturing Examples 1-11, Comparative Manufacturing Examples 1-5]

[0307] Various copolymers were manufactured using manufacturing examples 1 to 11 and comparative manufacturing examples 1 to 5 as described below.

[0308] <Single used>

[0309] (Single(A))

[0310] • "Dodecyl acrylate": R in the above general formula (a-1) a1 For hydrogen atoms, R a2 It is a compound of n-dodecyl (a straight-chain alkyl group with 12 carbon atoms).

[0311] • "Dodecyl methacrylate": In the above general formula (a-1), R a1 Methyl, R a2 It is a compound of n-dodecyl (a straight-chain alkyl group with 12 carbon atoms).

[0312] • "2-Ethylhexyl acrylate": R in the above general formula (a-1) a1 For hydrogen atoms, R a2 It is a compound of 2-ethylhexyl (a branched alkyl group with 8 carbon atoms).

[0313] • "Stearyl acrylate": R in the above general formula (a-1) a1 For hydrogen atoms, R a2 It is a compound with a stearyl group (a straight-chain alkyl group with 18 carbon atoms).

[0314] (Single(B))

[0315] • "2-Hydroxyethyl Acrylate": A monomer having an acryloyl group and a hydroxyl group as a polar group. The structural formula is shown below.

[0316] [Chemical Formula 3]

[0317]

[0318] • "2-Hydroxyethyl methacrylate": A monomer having a methacrylamide group and a hydroxyl group as a polar group. The structural formula is shown below.

[0319] [Chemical Formula 4]

[0320]

[0321] • "Carboxyethyl acrylate": A monomer having an acryloyl group and a carboxyl group as a polar group. The structural formula is shown below.

[0322] [Chemical Formula 5]

[0323]

[0324] • “N-[3-(dimethylamino)propyl]acrylamide (also known as: N,N-dimethylaminopropyl(methyl)acrylamide)”: A monomer having an acryloyl group and a nitrogen-containing group as a polar group. The structural formula is shown below.

[0325] [Chemical Formula 6]

[0326]

[0327] (Single(C))

[0328] • "Benzyl acrylate": A monomer with an acryloyl group as its polymerizable functional group and a benzene ring structure. More specifically, it is a monomer in the above general formula (c-1) where Y is an acryloyl group, L is an oxymethylene group, and Z is a phenyl group.

[0329] • "Benzyl methacrylate": A monomer with a polymerizable functional group of methacryloyl and a cyclic structure of benzene. More specifically, it is a monomer in the above general formula (c-1) where Y is methacryloyl, L is oxymethylene, and Z is phenyl.

[0330] • "Cyclohexyl acrylate": A monomer with an acryloyl functional group and a cyclohexane cyclic structure. More specifically, it is a monomer in the above general formula (c-1) where Y is acryloyl, L is -O-, and Z is cyclohexyl.

[0331] • "Furfuryl acrylate": A monomer with an acryloyl group as its polymerizable functional group and a furan ring structure. More specifically, it is a monomer in the above general formula (c-1) where Y is an acryloyl group, L is an oxymethylene group, and Z is a furan group.

[0332] • "Tetrahydrofurfuryl acrylate": A monomer with an acryloyl functional group and a tetrahydrofuran cyclic structure. Specifically, it is a monomer in the above general formula (c-1) where Y is an acryloyl group, L is an oxymethylene group, and Z is a tetrahydrofuran group.

[0333] <Manufacturing Example 1: Manufacturing of Copolymer (X)-1>

[0334] In a reaction vessel equipped with a stirring device, a heating and cooling device, a thermometer, a dropping funnel, and a nitrogen blowing tube, 20 g (83 mmol) of dodecyl acrylate as monomer (A), 3 g (26 mmol) of 2-hydroxyethyl acrylate as monomer (B), 5 g (31 mmol) of benzyl acrylate as monomer (C), and 28 g of bis(2-ethylhexyl) sebacate as solvent were added.

[0335] Next, nitrogen was purged from the reaction vessel, and 0.1 g (0.4 mmol) of 2,2'-azobis(2,4-dimethylpentanonitrile) and 0.08 g (0.4 mmol) of dodecyl mercaptan were added as initiators. The mixture was stirred and slowly heated to 75–85 °C for 6 hours. After the reaction was complete, unreacted monomers were removed by vacuum distillation to obtain copolymer (X)-1.

[0336] <Manufacturing Example 2: Manufacturing of Copolymer (X)-2>

[0337] 20 g (83 mmol) of dodecyl acrylate as monomer (A) and 28 g of bis(2-ethylhexyl) sebacate as solvent were added to a reaction vessel equipped with a stirring device, a heating and cooling device, a thermometer, a dropping funnel and a nitrogen blowing tube.

[0338] Next, nitrogen was purged from the reaction vessel. Then, 0.1 g (0.4 mmol) of 2,2'-azobis(2,4-dimethylpentanonitrile) and 0.13 g (0.4 mmol) of dodecyl cyanomethyl trithiocarbonate were added as initiators. The mixture was stirred and slowly heated at 75–85 °C for 6 hours. After confirming that more than 96% of the dodecyl acrylate had been converted to polymer, 5 g (31 mmol) of benzyl acrylate and 0.05 g (0.2 mmol) of 2,2'-azobis(2,4-dimethylpentanonitrile) were added as monomer (C), and the reaction was further carried out at 75–85 °C for 6 hours. After confirming that more than 96% of the benzyl acrylate had been converted to polymer, 3 g (26 mmol) of 2-hydroxyethyl acrylate and 0.05 g (0.2 mmol) of 2,2'-azobis(2,4-dimethylpentanonitrile) were added as monomer (B), and the reaction was further carried out at 75–85 °C for 6 hours. After the reaction was completed, unreacted monomers were removed by vacuum distillation to obtain copolymer (X)-2.

[0339] <Manufacturing Example 3: Manufacturing of Copolymer (X)-3>

[0340] The monomer (B) was changed to carboxyethyl acrylate, and the amount of monomers (A) to (C) was adjusted in the manner shown in Table 1 by mass ratio and molar ratio. Copolymer (X)-3 was manufactured by the same method as in Manufacturing Example 1.

[0341] <Manufacturing Example 4: Manufacturing of Copolymer (X)-4>

[0342] The monomer (B) was changed to N-[3-(dimethylamino)propyl]acrylamide, and the amount of monomers (A) to (C) was adjusted in such a way as shown in Table 1 by mass ratio and molar ratio. Copolymer (X)-4 was manufactured by the same method as in Manufacturing Example 1.

[0343] <Manufacturing Example 5: Manufacturing of Copolymer (X)-5>

[0344] Copolymer (X)-5 was manufactured by combining dodecyl acrylate and 2-ethylhexyl acrylate as monomers (A) and adjusting the addition amounts of monomers (A) to (C) in the manner shown in Table 1 by means of the same method as in Manufacturing Example 1.

[0345] <Manufacturing Example 6: Manufacturing of Copolymer (X)-6>

[0346] Copolymer (X)-6 was manufactured by combining dodecyl acrylate and stearyl acrylate as monomers (A) and adjusting the addition amounts of monomers (A) to (C) in the manner shown in Table 1 by means of the same method as in Manufacturing Example 1.

[0347] <Manufacturing Example 7: Manufacturing of Copolymer (X)-7>

[0348] The amount of monomers (A) to (C) added was adjusted in the manner shown in Table 1 to achieve the mass ratio and molar ratio, and copolymer (X)-7 was manufactured by the same method as in manufacturing example 1.

[0349] <Manufacturing Example 8: Manufacturing of Copolymer (X)-8>

[0350] The monomer (C) was changed to cyclohexyl acrylate, and the amount of monomers (A) to (C) was adjusted in the manner shown in Table 1 in terms of mass ratio and molar ratio. Copolymer (X)-8 was manufactured by the same method as in Manufacturing Example 1.

[0351] <Manufacturing Example 9: Manufacturing of Copolymer (X)-9>

[0352] Monomer (A) was changed to dodecyl methacrylate, monomer (B) was changed to 2-hydroxyethyl methacrylate, and monomer (C) was changed to benzyl methacrylate. The amount of monomers (A) to (C) was adjusted to achieve the mass ratio and molar ratio shown in Table 1. Copolymer (X)-9 was manufactured by the same method as in Manufacturing Example 1.

[0353] <Manufacturing Example 10: Manufacturing of Copolymer (X)-10>

[0354] As monomer (C), benzyl acrylate was added together with furfuryl acrylate, and the amount of monomers (A) to (C) was adjusted in such a way as shown in Table 1 by adjusting the mass ratio and molar ratio. Copolymer (X)-10 was manufactured by the same method as in Manufacturing Example 1.

[0355] <Manufacturing Example 11: Manufacturing of Copolymer (X)-11>

[0356] As monomer (C), tetrahydrofurfuryl acrylate was added together with benzyl acrylate, and the amount of monomers (A) to (C) was adjusted in such a way as shown in Table 1 by adjusting the mass ratio and molar ratio. Copolymer (X)-11 was manufactured by the same method as in Manufacturing Example 1.

[0357] <Comparative Manufacturing Example 1: Manufacturing of Copolymer (X')-1>

[0358] Without adding monomer (C), monomer (B) was replaced with N-[3-(dimethylamino)propyl]acrylamide, and the amounts of monomers (A) and (B) were adjusted to the mass ratio and molar ratio shown in Table 2. Copolymer (X')-1 was manufactured by the same method as in Manufacturing Example 1.

[0359] <Comparative Manufacturing Example 2: Manufacturing of Polymer (X')-2>

[0360] Polymer (X')-2 was manufactured using the same method as in Manufacturing Example 1, without adding monomers (B) and (C).

[0361] It should be noted that the composite obtained in Comparative Manufacturing Example 2 is strictly speaking a polymer rather than a copolymer, but for the sake of simplicity, this polymer will also be referred to as a copolymer in the following description.

[0362] <Comparative Manufacturing Example 3: Manufacturing of Copolymer (X')-3>

[0363] Without adding monomer (B), the amounts of monomers (A) and (C) were adjusted to achieve the mass ratio and molar ratio shown in Table 2, and copolymer (X')-3 was manufactured using the same method as in Manufacturing Example 1.

[0364] <Comparative Manufacturing Example 4: Manufacturing of Copolymer (X')-4>

[0365] Without adding monomer (C), the amounts of monomers (A) and (B) were adjusted to achieve the mass ratio and molar ratio shown in Table 2, and copolymer (X')-4 was manufactured using the same method as in Manufacturing Example 1.

[0366] <Comparative Manufacturing Example 5: Manufacturing of Copolymer (X')-5>

[0367] The amount of monomers (A) to (C) added was adjusted to the mass ratio and molar ratio shown in Table 2, and copolymer (X')-5 was manufactured by the same method as in manufacturing example 1.

[0368] [Examples 1-11, Comparative Examples 1-5]

[0369] The lubricating oil base oil was thoroughly mixed with each copolymer manufactured in Manufacturing Examples 1-11 and Comparative Examples 1-5 to prepare the lubricating oil compositions of Examples 1-11 and Comparative Examples 1-5, respectively.

[0370] The base oil for the lubricating oil is mineral oil (kinematic viscosity at 100℃: 5.3 mm). 2 / s, viscosity index: 104, API classification: Group II).

[0371] The content of lubricating base oil in the lubricating oil composition is 99% by mass, based on the total amount of the lubricating oil composition.

[0372] The copolymers manufactured in Manufacturing Examples 1-11 and Comparative Manufacturing Examples 1-5 were formulated into lubricating oil base oils in a state of dissolution in bis(2-ethylhexyl) sebacate, which served as a polymerization solvent (hereinafter also referred to as "solvent"). The mixing ratio of the copolymer to bis(2-ethylhexyl) sebacate was set to 1:1 (mass ratio).

[0373] The content of copolymers (including solvents) in the lubricating oil composition is 1% by mass based on the total amount of the lubricating oil composition. Therefore, the content of copolymers (the content of solvent-free copolymers) in the lubricating oil composition is 0.5% by mass based on the total amount of the lubricating oil composition.

[0374] [Evaluation Method]

[0375] The following tests were performed to evaluate the solubility and wear resistance in mineral oil.

[0376] Evaluation of solubility in lubricating oil base oils (mineral oils)

[0377] The above-mentioned mineral oil (kinematic viscosity at 100℃: 5.3 mm) 2 / s, viscosity index: 104, API classification: Group II) added 1% by mass of each copolymer (solvent-free copolymer) manufactured in Manufacturing Examples 1-11 and Comparative Manufacturing Examples 1-5. Next, the mineral oil was heated to 80°C, stirred for 30 minutes, and then allowed to stand at room temperature (25°C). Then, the state of the oil at room temperature was visually evaluated. The evaluation criteria are as follows.

[0378] • Rating "A": Transparent.

[0379] • Evaluation "B": Precipitation and turbidity were observed.

[0380] <Evaluation of Abrasion Resistance (Ball-Disc Test)>

[0381] Using a high-speed reciprocating friction testing machine TE77 (manufactured by Phoenix Tribology), a lubricating oil composition is introduced between the test plate and the test ball. The test ball is moved under the following conditions to conduct the test, and the wear mark diameter of the test ball after the test is measured.

[0382] • Test plate material: SUJ2, shape: 58mm (length) × 38mm (width) × 3.9mm (thickness)

[0383] • Test ball material: SUJ2, diameter 10mm

[0384] • Oil supply conditions: oil bath, oil volume 3mL

[0385] • Load: 50N (5 minutes) → 100N (5 minutes) → 150N (5 minutes) → 200N (5 minutes)

[0386] Temperature: 100℃

[0387] • Amplitude: 10mm

[0388] • Frequency: 10Hz

[0389] The smaller the value of the wear mark diameter, the better the lubricating oil composition in terms of wear resistance.

[0390] In this embodiment, lubricating oil compositions with wear marks diameter less than 520 μm are judged to be qualified.

[0391] The results are shown in Tables 1 and 2.

[0392] [Table 1]

[0393]

[0394] [Table 2]

[0395] Table 2

[0396]

[0397] The following information can be obtained from Table 1.

[0398] As shown in Examples 1 to 11, the copolymer containing structural units (a) derived from monomers (A) having (meth)acryloyl groups and straight-chain or branched alkyl groups having 6 or more and 24 or fewer carbon atoms, structural units (b) derived from monomers (B) having (meth)acryloyl groups and polar groups, and structural units (c) derived from monomers (C) having polymerizable functional groups and cyclic structural groups, wherein the content of structural unit (a) is 43 mol% or more based on all structural units of the copolymer (X) and the mass-average molecular weight (Mw) is 5000 or more and 90000 or less, exhibits excellent solubility in lubricating oil base oil (mineral oil) and can impart sufficient wear resistance to the lubricating oil composition.

[0399] The following information can be found in Table 2.

[0400] According to the results shown in Comparative Example 2, although the copolymer containing structural units (a) derived from monomers (A) having (meth)acryloyl groups and straight-chain or branched alkyl groups with 6 or more and 24 or fewer carbon atoms, and not containing structural units (b) derived from monomers (B) having (meth)acryloyl groups and polar groups, and structural units (c) derived from monomers (C) having polymerizable functional groups and cyclic structural groups, has excellent solubility in lubricating oil base oils, it cannot impart sufficient wear resistance to the lubricating oil composition.

[0401] According to the results shown in Comparative Examples 1 and 4, although the copolymer containing structural units (a) derived from monomers (A) having (meth)acryloyl groups and straight-chain or branched alkyl groups having 6 or more and 24 carbon atoms, structural units (b) derived from monomers (B) having (meth)acryloyl groups and polar groups, and structural units (c) not derived from monomers (C) having polymerizable functional groups and cyclic structural groups, has excellent solubility in lubricating oil base oils, it cannot impart sufficient wear resistance to the lubricating oil composition.

[0402] According to the results shown in Comparative Example 3, although the copolymer containing structural units (a) derived from monomers (A) having (meth)acryloyl groups and straight-chain or branched alkyl groups with 6 or more and 24 or fewer carbon atoms, structural units (c) derived from monomers (C) having polymerizable functional groups and cyclic structural groups, and structural units (b) not derived from monomers (B) having (meth)acryloyl groups and polar groups, has excellent solubility in lubricating oil base oils, it cannot impart sufficient wear resistance to the lubricating oil composition.

[0403] According to the results shown in Comparative Example 5, even copolymers containing structural units (a) from monomers (A) having (meth)acryloyl groups and straight-chain or branched alkyl groups with 6 or more and 24 or fewer carbon atoms, structural units (b) from monomers (B) having (meth)acryloyl groups and polar groups, and structural units (c) from monomers (C) having polymerizable functional groups and cyclic structural groups, exhibit poor solubility in lubricating oil base oils if the content of structural unit (a) is less than 43 mol% based on all structural units of the copolymer.

Claims

1. A lubricating oil additive composition comprising a copolymer X containing structural units a to c, • Structural unit a: A structural unit derived from monomer A having a (meth)acryloyl group and a straight-chain or branched alkyl group having 6 or more carbon atoms and 24 or fewer carbon atoms. • Structural unit b: A structural unit derived from monomer B, which has a (meth)acryloyl group and a polar group. • Structural unit c: A structural unit derived from monomer C, which possesses polymerizable functional groups and cyclic structural groups. The content of structural unit a, based on all structural units of copolymer X, is 43 mol% or more. The structural unit a comprises a structural unit a1 derived from the monomer A1 shown in the following general formula (a-1). In the general formula (a-1), R a1 R represents a hydrogen atom or a methyl group. a2 Alkyl groups, representing straight-chain or branched alkyl groups with 6 or more but less than 24 carbon atoms. The structural unit b comprises a structural unit b1 derived from a monomer B1 having one or more groups selected from nitrogen-containing groups, hydroxyl groups, and carboxyl groups as the polar group. Based on all structural units of structural unit b, the content of structural unit b2 derived from monomer B2 having polyoxyalkylene as the polar group is less than 5 mol%. The copolymer X has a mass-average molecular weight Mw of 5000 or more and 90000 or less. The monomer C includes monomer C1. The monomer C1 is a monomer represented by the following general formula (c-1). YLZ (c-1) In the general formula (c-1), Y represents a polymerizable functional group, L represents a direct bonding or linking group, and Z represents a cyclic structural group. The polymerizable functional group of Y is chosen to be acryloyl or methacryloyl. The linking group selected as L is a divalent aliphatic hydrocarbon group with 1 to 4 carbon atoms, a divalent group with 6 to 10 carbon atoms having a cyclic structure, -O-, an alkylene group with 1 to 4 carbon atoms, or a polyalkylene group with 1 to 4 carbon atoms. The cyclic group selected as Z is a monovalent cyclic group formed by removing one hydrogen atom from any of the cyclic structures (I) to (III) below. (I) Aromatic rings with 6 or more but less than 14 carbon atoms (II) Alicyclic rings with 3 or more but less than 14 carbon atoms (III) A heterocycle containing 3 or more but less than 14 heteroatoms selected from nitrogen and oxygen atoms.

2. The additive composition for lubricating oil according to claim 1, wherein, Selected as R a2 The straight-chain alkyl group with 6 or more carbon atoms and 24 or fewer carbon atoms is selected from n-hexyl, n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl, n-docodialkyl, and n-tetradecyl.

3. The additive composition for lubricating oil according to claim 1, wherein, Selected as R a2 The branched alkyl group with 6 or more carbon atoms and 24 or fewer carbon atoms is selected from isooctyl, tert-octyl, 2-ethylhexyl, isononyl, isodecyl, and isooctadecyl.

4. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The content of structural unit a1 is 50 mol% to 100 mol% based on all structural units of structural unit a.

5. The additive composition for lubricating oil according to claim 1, wherein, The monomer having a nitrogen-containing group as the polar group is selected from one or more of the following: acrylic monomers containing amide groups, acrylic monomers containing primary amino groups, acrylic monomers containing secondary amino groups, acrylic monomers containing tertiary amino groups, acrylic monomers containing nitrile groups, acrylic monomers containing urea groups, and acrylic monomers containing urethane groups.

6. The additive composition for lubricating oil according to claim 5, wherein, The amide-containing acrylic monomer is selected from one or more of monoalkylamino(meth)acrylamide, monoalkylaminoalkyl(meth)acrylamide, dialkylamino(meth)acrylamide, and dialkylaminoalkyl(meth)acrylamide.

7. The additive composition for lubricating oil according to claim 1, wherein, The monomer having a hydroxyl group as the polar group is an acrylic monomer containing hydroxyl groups.

8. The additive composition for lubricating oil according to claim 7, wherein, The hydroxyl-containing acrylic monomer is selected from one or more of (meth)acrylate hydroxyalkyl esters, monohydroxyalkyl-substituted (meth)acrylamides, and dihydroxyalkyl-substituted (meth)acrylamides.

9. The additive composition for lubricating oil according to claim 1, wherein, The monomer having a carboxyl group as the polar group is an acrylic monomer containing a carboxyl group.

10. The additive composition for lubricating oil according to claim 9, wherein, The carboxyl-containing acrylic monomer is a carboxyl alkyl ester of (meth)acrylate.

11. The additive composition for lubricating oil according to claim 1, wherein, The content of structural unit b1 is 50 mol% to 100 mol% based on all structural units of structural unit b.

12. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The aromatic rings having 6 or more but less than 14 carbon atoms are selected from benzene, naphthalene, anthracene, and phenanthrene.

13. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The alicyclic ring with 3 or more but less than 14 carbon atoms is selected from cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, cyclododecane, cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, cyclododecene, norbornane, adamantane, norbornene, and adamantaneene.

14. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The heterocycles having 3 or more but less than 14 cyclic atoms are selected from aziridine, ethylene oxide, diaziridine, oxapropidine, dioxacyclopropane, acrylonitrile, ethylene oxide, dioxacyclopropane, aziridine, oxacyclobutane, dioxacyclobutane, dioxacyclobutane, aziridine, oxacyclobutane, dioxacyclobutane, pyrrolidine, tetrahydrofuran, imidazoline, pyrazolidine, oxazolidine, isoxazolidine, dioxazolidine, and dioxacyclobutane. Cyclohexane, pyrrole, furan, imidazole, pyrazole, oxazole, isoxazole, triazole, furazolidone, oxadiazole, dioxazole, tetrazolium, oxa-tetrazolium, pentaazole, piperidine, tetrahydropyran, piperazine, morpholine, dioxane, hexahydro-1,3,5-triazine, trioxane, pyridine, pyran, diazine, oxazine, dioxazine, triazine, tetraazine, pentaazine, azircycloheptane, oxa-cycloheptane, diazircycloheptane, azircycloheptane, oxa-cycloheptane, and diazircycloheptane.

15. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The content of structural unit c1 from the monomer C1 is 50 mol% to 100 mol% based on all structural units of structural unit c.

16. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The content of structural unit a from monomer A is 50 mol% to 84 mol% based on all structural units of copolymer X.

17. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The content of the structural unit b from the monomer B is 9 mol% or more based on all structural units of the copolymer X.

18. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The content of structural unit b from monomer B is 9 mol% to 50 mol% based on all structural units of copolymer X.

19. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The content of the structural unit c from the monomer C is 7 mol% or more and 30 mol% or less, based on all structural units of the copolymer X.

20. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, In the copolymer X, the ratio of structural unit b to structural unit a [b / a] is 0.15 to 0.50 in molar ratio.

21. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, In the copolymer X, the ratio of structural unit c to structural unit a [c / a] is 0.10 to 0.48 in molar ratio.

22. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The molecular weight distribution of copolymer X, Mw / Mn, is greater than 1.01 and less than 3.

5.

23. The additive composition for lubricating oil according to any one of claims 1 to 3, wherein, The content of copolymer X is 50% by mass or more, based on the total amount of the lubricating oil additive composition.

24. The lubricating oil additive composition according to any one of claims 1 to 3, wherein it is used as a friction modifier.

25. A method of use, wherein, The lubricating oil additive composition according to any one of claims 1 to 23 is used as a friction modifier.

26. A lubricating oil composition comprising the lubricating oil additive composition according to any one of claims 1 to 24 and a lubricating oil base oil.

27. The lubricating oil composition according to claim 26, wherein, The content of copolymer X is 0.1% to 10% by mass based on the total amount of the lubricating oil composition.

28. The lubricating oil composition according to claim 26 or 27, wherein, The base oil of the lubricating oil is selected from one or more mineral oils and synthetic oils.

29. The lubricating oil composition according to claim 26 or 27, wherein, The kinematic viscosity of the lubricating oil base oil at 100°C is 1 mm. 2 / s~50mm 2 / s.

30. The lubricating oil composition according to claim 26 or 27, wherein, The viscosity index of the base oil for the lubricating oil is above 80.

31. The lubricating oil composition according to claim 26 or 27, wherein, It also contains one or more additives selected from antioxidants, oiliness agents, detergents and dispersants, viscosity index improvers, rust inhibitors, metal passivators, and defoamers.

32. The lubricating oil composition according to claim 26 or 27, wherein its kinematic viscosity at 100°C is 1.0 mm. 2 / s~50mm 2 / s.

33. The lubricating oil composition according to claim 26 or 27, wherein the viscosity index is 90 or higher.

34. A manufacturing method for producing the lubricating oil additive composition of claim 1. The process S includes polymerizing monomer A, monomer B, and monomer C to produce copolymer X.

35. The manufacturing method according to claim 34, wherein, The copolymer X is manufactured by a polymerization method selected from emulsion polymerization, suspension polymerization and solution polymerization.

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