Conductive agent and lubricant composition

Abstract

To provide a conductive agent and a lubricant composition, which are highly soluble in a solvent and base oil, are hardly caused sedimentation over time, and exhibit little decrease in conductivity.SOLUTION: There is provided a conductive agent, containing a copolymer (A) having, as essential constituent monomers, a monomer (a) represented by a formula (1), and a (meth)acrylic acid alkyl ester monomer (b) having an alkyl group having 8 to 14 carbon atoms. The conductive agent in a monomer constituting the copolymer (A) has a weight ratio (b / a) of the monomer (b) to a weight of the monomer (a) of 4 to 20.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a conductive agent and a lubricant composition. [Background technology]

[0002] Conventionally, conductive agents having a quaternary ammonium salt at the side chain end of a (meth)acrylic copolymer, carbon black, ionic liquids, and the like have been known to impart antistatic properties and conductivity to lubricants (Patent Documents 1 and 2). However, when using conductive agents having a quaternary ammonium salt at the side chain end of a (meth)acrylic copolymer in a lubricating oil, for example, the monomer containing the quaternary ammonium salt, which is a constituent, is water-soluble. Even when copolymerized with an oil-soluble (meth)acrylic acid alkyl ester, the resulting (meth)acrylic copolymer has poor solubility in base oils, making it usable only with certain base oils or limited to small amounts. Furthermore, carbon black initially exhibits excellent conductivity, but because it is insoluble in base oils and solvents, it settles over time, resulting in a decrease in conductivity (Patent Documents 3 and 4). Furthermore, ionic liquids have poor solubility in base oils, making them usable only with certain base oils (Patent Document 5). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 98 / 00482 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-31715 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-304276 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-250353 [Patent Document 5] Japanese Patent Application Laid-Open No. 2007-99826 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a conductive agent and lubricant composition that is highly soluble in solvents and base oils, does not settle over time, and exhibits little decrease in conductivity. [Means for solving the problem]

[0005] As a result of extensive research, the present inventors have arrived at the present invention. That is, the present invention provides a conductive agent containing a copolymer (A) having, as essential constituent monomers, a monomer (a) represented by the following general formula (1) and a (meth)acrylic acid alkyl ester monomer (b) having an alkyl group having 8 to 14 carbon atoms, wherein, among the monomers constituting copolymer (A), the weight ratio (b / a) of the monomer (b) to the weight of the monomer (a) is 4 to 20; and a lubricant composition containing the conductive agent and a base oil (B).

[0006] [ka] [In formula (1), R 1 ~R 3 each independently represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom; -X- represents a group represented by -O- or -NH-; Q represents an alkylene group having 1 to 4 carbon atoms; Z - represents the residue obtained by removing a proton from a protonic acid. [Effects of the Invention]

[0007] The conductive agent of the present invention has high solubility in solvents and base oils, and a lubricant composition containing the conductive agent of the present invention exhibits the effects of being free from sedimentation over time and exhibiting little decrease in conductivity. DETAILED DESCRIPTION OF THE INVENTION

[0008] The conductive agent of the present invention contains a copolymer (A) having, as essential constituent monomers, a constituent monomer (a) represented by the following general formula (1) and a (meth)acrylic acid alkyl ester monomer (b) having an alkyl group having 8 to 14 carbon atoms, and in the monomers constituting the copolymer (A), the weight ratio (b / a) of the monomer (b) to the weight of the monomer (a) is 4 to 20:

[0009] [ka] [In formula (1), R 1 ~R 3 each independently represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom; -X- represents a group represented by -O- or -NH-; Q represents an alkylene group having 1 to 4 carbon atoms; Z - represents the residue obtained by removing a proton from a protonic acid.

[0010] <Copolymer (A)> In the present invention, the copolymer (A) contains the monomer (a) represented by the general formula (1) as a constituent monomer. By containing the monomer (a) as a constituent monomer, electrical conductivity can be exhibited. The monomer (a) may be used alone or in combination of two or more. In general formula (1), R 1 ~R 3 each independently represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. R 1 ~R 3 From the viewpoint of electrical conductivity, R is preferably a methyl group, an ethyl group, or an isopropyl group, more preferably a methyl group or an ethyl group, and particularly preferably 1 ~R 3 are all methyl groups.

[0011] In the general formula (1), -X- is a group represented by -O- or -NH-, and from the viewpoint of oil solubility, -O- is preferred.

[0012] In the general formula (1), Q is an alkylene group having 1 to 4 carbon atoms, and examples thereof include a methylene group, an ethylene group, a propylene group, and a butylene group. As Q, from the viewpoints of preventing sedimentation, preventing a decrease in electrical conductivity, and oil solubility, a methylene group, an ethylene group, and a propylene group are preferred, and an ethylene group is more preferred.

[0013] In general formula (1), Z - represents a residue obtained by removing a proton from a protonic acid. Examples of protonic acids include organic acids (e.g., organic sulfonic acids, carboxylic acids, etc.) and inorganic acids (e.g., hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, phosphoric acid, etc.). The organic sulfonic acids include those having one or more carbon atoms and a number average molecular weight of 1,000 or less, such as monovalent organic sulfonic acids [aromatic sulfonic acids (benzenesulfonic acid, pentadecylbenzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, naphthalenesulfonic acid, dodecylbenzenesulfonic acid, dodecylnaphthalenesulfonic acid, etc.), alicyclic sulfonic acids (camphorsulfonic acid, etc.), aliphatic sulfonic acids (methanesulfonic acid, ethanesulfonic acid, butanesulfonic acid, etc.)]; and polyvalent organic sulfonic acids having two or more sulfo groups in the molecule. sulfonic acids [aromatic polysulfonic acids (benzene disulfonic acid, naphthalenedisulfonic acid, toluene disulfonic acid, methylnaphthalenedisulfonic acid, anthracene disulfonic acid, anthraquinone disulfonic acid, phenanthrene disulfonic acid, fluorenone disulfonic acid, carbazole disulfonic acid, diphenylmethane disulfonic acid, terphenyl disulfonic acid, terphenyl trisulfonic acid, naphthalenedisulfonic acid-formalin condensate, etc.), aliphatic polysulfonic acids (ethane disulfonic acid, propane disulfonic acid, etc.)]. Carboxylic acids include those having one or more carbon atoms and a number average molecular weight of 1,000 or less, such as aliphatic carboxylic acids, aromatic carboxylic acids, araliphatic carboxylic acids, alicyclic carboxylic acids, and carboxylic acids having a substituent (at least one selected from the group consisting of a hydroxyl group, an alkyloxy group, a halogen group, a nitro group, a cyano group, and an amino group). Specific examples include aliphatic carboxylic acids [acetic acid, butyric acid, lactic acid, formic acid, oxalic acid, (meth)acrylic acid, etc.], aromatic carboxylic acids (benzoic acid, etc.), carboxylic acids having a substituent (monochloroacetic acid, monofluoroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, pentafluoroacetic acid, pentadecafluorooctanoic acid, o-, m-, or p-chlorobenzoic acid, o-, m-, or p-nitrobenzoic acid, o-methoxybenzoic acid, p-oxybenzoic acid, salicylic acid, 5-aminosalicylic acid, etc.). As the protonic acid, from the viewpoint of versatility, organic sulfonic acids, carboxylic acids and hydrochloric acid are preferred, and hydrochloric acid is more preferred.

[0014] Examples of the monomer (a) include, when the protonic acid is an inorganic acid, those of hydrochloric acid {e.g., 2-(meth)acryloyloxyethyltrimethylammonium chloride, 2-(meth)acryloyloxyethyl-N-ethyl-N,N-dimethylammonium chloride, 2-(meth)acryloyloxyethyl-N,N-diethyl-N-methylammonium chloride, [1-{(meth)acryloyloxy}ethyl]trimethylammonium chloride, 2-(meth)acryloyloxyethyl-N,N,N-triethylammonium chloride, N,N,N -Trimethyl-1-(2-methyl-1-oxo-2-propenyloxy)-2-propanaminium chloride, N,N,N-trimethyl-2-[(2-methyl-1-oxo-2-propenyl)oxy]-1-propanaminium chloride, 3-(meth)acryloyloxy-N,N,N-trimethyl-1-propanaminium chloride, 3-(meth)acryloyloxy-N-ethyl-N,N-dimethyl-1-propanaminium chloride, 3-(meth)acryloyloxy-N,N-diethyl-N-methyl-1-propanaminium chloride, 3 -(Meth)acryloyloxy-N,N,N-triethyl-1-propanaminium chloride, 4-(meth)acryloyloxy-N,N,N-trimethyl-1-butanaminium chloride, 4-(meth)acryloyloxy-N-ethyl-N,N-dimethyl-1-butanaminium chloride, 4-(meth)acryloyloxy-N,N-diethyl-N-methyl-1-butanaminium chloride, 4-(meth)acryloyloxy-N,N,N-triethyl-1-butanaminium chloride, N-benzyl-N,N-dimethylammonium-2 -((meth)acryloyloxy)ethylammonium chloride, etc.}, those in which the protonic acid is sulfuric acid {for example, 2-(meth)acryloyloxyethyltrimethylammonium sulfate, 2-(meth)acryloyloxyethyl-N-ethyl-N,N-dimethylammonium sulfate, 2-(meth)acryloyloxyethyl-N,N-diethyl-N-methylammonium sulfate, [1-{(meth)acryloyloxy}ethyl]trimethylammonium sulfate, 2-(meth)acryloyloxyethyl-N,N,N-triethylammonium sulfate, N,N,N-trimethyl-1-(2-methyl-1-oxo-2-propenyloxy)-2-propanaminium sulfate, N,N,N-trimethyl-2-[(2-methyl-1-oxo-2-propenyl)oxy]-1-propanaminium sulfate, 3-(meth)acryloyloxy-N,N,N-trimethyl-1-propanaminium sulfate, 3-(meth)acryloyloxy-N-ethyl-N,N-dimethyl-1-propanaminium sulfate, 3-(meth)acryloyloxy-N,N-diethyl-N-methyl-1-propanaminium aminium sulfate, 3-(meth)acryloyloxy-N,N,N-triethyl-1-propanaminium sulfate, 4-(meth)acryloyloxy-N,N,N-trimethyl-1-butanaminium sulfate, 4-(meth)acryloyloxy-N-ethyl-N,N-dimethyl-1-butanaminium sulfate, 4-(meth)acryloyloxy-N,N-diethyl-N-methyl-1-butanaminium sulfate, 4-(meth)acryloyloxy-N,N,N-triethyl-1-butanaminium sulfate, etc.

[0015] For example, when the protonic acid is an organic acid, for example, the protonic acid is methanesulfonic acid {e.g., 2-(meth)acryloyloxyethyltrimethylammonium methanesulfonate, 2-(meth)acryloyloxyethyl-N-ethyl-N,N-dimethylammonium methanesulfonate, 2-(meth)acryloyloxyethyl-N,N-diethyl-N-methylammonium methanesulfonate, [1-{(meth)acryloyloxy}ethyl N,N,N-trimethyl-1-(2-methyl-1-oxo-2-propenyloxy)-2-propanaminium methanesulfonate, N,N,N-trimethyl-2-[(2-methyl-1-oxo-2-propenyl)oxy]-1-propanaminium methanesulfonate, 3-(meth)acryloyloxyethyl-N,N,N-triethylammonium methanesulfonate, N,N,N-trimethyl-1-(2-methyl-1-oxo-2-propenyloxy)-2-propanaminium methanesulfonate, N,N,N-trimethyl-2-[(2-methyl-1-oxo-2-propenyl)oxy]-1-propanaminium methanesulfonate, 3-(meth)acryloyloxy-N,N,N-trimethyl-1-propanaminium methanesulfonate, 3-(meth)acryloyloxy-N-ethyl-N,N-dimethyl-1-propanaminium methanesulfonate, 3-(meth)acryloyloxy-N,N-diethyl-N-methyl-1-propanaminium methanesulfonate, 3-(meth)acryloyloxy-N,N,N-triethyl-1-propanaminium methanesulfonate, 4-(meth)acryloyloxy acryloyloxy-N,N,N-trimethyl-1-butanaminium methanesulfonate, 4-(meth)acryloyloxy-N-ethyl-N,N-dimethyl-1-butanaminium methanesulfonate, 4-(meth)acryloyloxy-N,N-diethyl-N-methyl-1-butanaminium methanesulfonate, 4-(meth)acryloyloxy-N,N,N-triethyl-1-butanaminium methanesulfonate, and the like. In the present invention, "(meth)acrylate" means "acrylate and / or methacrylate".

[0016] The copolymer (A) of the present invention contains, as a constituent monomer, a (meth)acrylic acid alkyl ester monomer (b) having an alkyl group having 8 to 14 carbon atoms. By containing the monomer (b) as a constituent monomer, the copolymer (A) becomes easily soluble in various base oils (B). The monomer (b) may be used alone or in combination of two or more.

[0017] Examples of the alkyl group having 8 to 14 carbon atoms include linear alkyl groups (e.g., n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, and n-tetradecyl groups), and branched alkyl groups (e.g., isooctyl, 2-ethylhexyl, isononyl, isodecyl, isoundecyl, isododecyl, isotridecyl, isotetradecyl, and 2-butyloctyl groups). As the alkyl group, from the viewpoints of preventing sedimentation, preventing a decrease in conductivity, and oil solubility, an alkyl group having 8 to 12 carbon atoms is preferred, more preferably a 2-ethylhexyl group or an n-dodecyl group, and particularly preferably an n-dodecyl group.

[0018] Examples of the monomer (b) include n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, isoundecyl (meth)acrylate, isododecyl (meth)acrylate, 2-butyloctyl (meth)acrylate, tridecyl (meth)acrylate, and tetradecyl (meth)acrylate. As the monomer (b), from the viewpoints of preventing sedimentation, preventing a decrease in conductivity, and oil solubility, a (meth)acrylic acid alkyl ester having an alkyl group of 8 to 12 carbon atoms is preferred, 2-ethylhexyl (meth)acrylate and n-dodecyl (meth)acrylate are more preferred, and n-dodecyl (meth)acrylate is particularly preferred.

[0019] The molar average carbon number of the alkyl group of the monomer (b) among the monomers constituting the copolymer (A) is preferably 8 to 12, more preferably 10 to 12, from the viewpoints of preventing sedimentation, preventing a decrease in electrical conductivity, and oil solubility.

[0020] In the present invention, the copolymer (A) may be obtained by copolymerizing, in addition to the monomers (a) and (b), a (meth)acrylic acid alkyl ester monomer (d) having an alkyl group with 1 to 7 carbon atoms, a (meth)acrylic acid alkyl ester monomer (e) having an alkyl group with 15 to 50 carbon atoms, a nitrogen atom-containing monomer (f) other than the monomer (a), a hydroxyl group-containing monomer (g), a phosphate ester group-containing monomer (h), an aromatic ring-containing vinyl monomer (i), a monomer (j) having two or more unsaturated groups, and other monomers (k) to (o).

[0021] Examples of the (meth)acrylic acid alkyl ester monomer (d) having an alkyl group having 1 to 7 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isopentyl (meth)acrylate, isohexyl (meth)acrylate, and isoheptyl (meth)acrylate. The monomer (d) may be used alone or in combination of two or more.

[0022] Examples of the (meth)acrylic acid alkyl ester monomer (e) having an alkyl group having 15 to 50 carbon atoms include n-pentadecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-heptadecyl (meth)acrylate, n-octadecyl (meth)acrylate, n-nonadecyl (meth)acrylate, n-icosyl (meth)acrylate, n-docosyl (meth)acrylate, n-tetracosyl (meth)acrylate, n-hexacosyl (meth)acrylate, n-octacosyl (meth)acrylate, and n-triacontyl (meth)acrylate. Examples of the acrylate include isotridecyl (meth)acrylate, isotetradecyl (meth)acrylate, isopentadecyl (meth)acrylate, isohexadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, isooctadecyl (meth)acrylate, isononadecyl (meth)acrylate, isoicosyl (meth)acrylate, 2-decyltetradecyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, 2-tetradecyloctadecyl (meth)acrylate, and 2-hexadecylicosyl (meth)acrylate. The monomer (e) may be used alone or in combination of two or more.

[0023] Examples of the nitrogen atom-containing monomer (f) include the following monomers (f1) to (f4). Amide group-containing monomer (f1): (meth)acrylamide, monoalkyl(meth)acrylamide [one having one alkyl group of 1 to 4 carbon atoms bonded to a nitrogen atom; for example, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and Nn- or isobutyl(meth)acrylamide, etc.], dialkyl(meth)acrylamide [one having two alkyl groups of 1 to 4 carbon atoms bonded to a nitrogen atom; for example, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, and N,N-di-n-butyl(meth)acrylamide, etc.], (meth)acrylamide having a primary, secondary, or tertiary amino group [for example, N-(N'-monoalkylaminoalkyl)(meth)acrylamide [one having an aminoalkyl group (2 to 6 carbon atoms) in which one alkyl group of 1 to 4 carbon atoms is bonded to a nitrogen atom; for example, N-(N'-methylaminoethyl)(meth)acrylamide, N-( N-(N'-ethylaminoethyl)(meth)acrylamide, N-(N'-isopropylamino-n-butyl)(meth)acrylamide, and N-(N'-n- or isobutylamino-n-butyl)(meth)acrylamide, etc.), N-(N',N'-dialkylaminoalkyl)(meth)acrylamides [those having an aminoalkyl group (having 2 to 6 carbon atoms) in which two alkyl groups each having 1 to 4 carbon atoms are bonded to the nitrogen atom of the aminoalkyl group; for example, N-(N',N'-dimethylaminoethyl)(meth)acrylamide, N-(N',N'-diethylaminoethyl)(meth)acrylamide, N-(N',N'-dimethylaminopropyl)(meth)acrylamide, and N-(N',N'-di-n-butylaminobutyl)(meth)acrylamide, etc.]; and N-vinylcarboxylic acid amides [N-vinylformamide, N-vinylacetamide, N-vinyl-n- or isopropionic acid amide, and N-vinylhydroxyacetamide, etc.].

[0024] Nitro group-containing monomer (f2): Examples include 4-nitrostyrene.

[0025] Monomers containing primary to tertiary amino groups (f3): Primary amino group-containing monomers {C3-C6 alkenylamines [(meth)allylamine, crotylamine, etc.], aminoalkyl (C2-C6) (meth)acrylates [aminoethyl (meth)acrylate, etc.]}; secondary amino group-containing monomers {monoalkylaminoalkyl (meth)acrylates [those having an aminoalkyl group (C2-C6) in which one alkyl group having C1-C6 is bonded to a nitrogen atom; for example, Nt-butylaminoethyl (meth)acrylate and N-methylaminoethyl (meth)acrylate, etc.], dialkenylamines having C6-C12 [di(meth)allylamine, etc.]}; tertiary amino group-containing monomers {dialkylamino Examples of the aminoalkyl (meth)acrylate include an aminoalkyl group (having 2 to 6 carbon atoms) in which two alkyl groups having 1 to 6 carbon atoms are bonded to a nitrogen atom; for example, N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate, etc.; an alicyclic (meth)acrylate having a nitrogen atom [morpholinoethyl (meth)acrylate, etc.]; and an aromatic monomer [N-(N',N'-diphenylaminoethyl)(meth)acrylamide, N,N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone, and N-vinylthiopyrrolidone].

[0026] Nitrile group-containing monomer (f4): (Meth)acrylonitrile and the like.

[0027] Of the nitrogen atom-containing monomers (f), (f1) and (f3) are preferred, and N-(N',N'-diphenylaminoethyl)(meth)acrylamide, N-(N',N'-dimethylaminoethyl)(meth)acrylamide, N-(N',N'-diethylaminoethyl)(meth)acrylamide, N-(N',N'-dimethylaminopropyl)(meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and N,N-diethylaminoethyl (meth)acrylate are more preferred. The monomer (f) may be used alone or in combination of two or more.

[0028] Hydroxyl group-containing monomer (g) Hydroxyl group-containing aromatic monomers (e.g., p-hydroxystyrene), hydroxyalkyl (meth)acrylates (having 2 to 6 carbon atoms) [2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxyisobutyl (meth)acrylate, etc.], mono- or bis-hydroxyalkyl (having 1 to 4 carbon atoms) substituted (meth)acrylamides [N,N-bis(hydroxymethyl)(meth)acrylamide, N,N-bis(hydroxypropyl)(meth)acrylamide, N,N-bis(2-hydroxybutyl)(meth)acrylamide, etc.], vinyl alcohol, alkenols having 3 to 12 carbon atoms [(meth)allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-octenol, 1-undecenol, etc.], alkene monools or alkene diols having 4 to 12 carbon atoms [1-buten-3-ol, 2-buten-1-ol, 2-butene-1,4-diol, etc.], hydroxyalkyl (C1 to C6) alkenyl (C3 to C10) ethers (2-hydroxyethylpropenyl ether, etc.), alkenyl (C3 to C10) ethers or (meth)acrylates of polyhydric (tri-octahydric) alcohols (glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, sugars, sucrose, etc.) [sucrose (meth)allyl ether, etc.], and the like; Examples thereof include polyoxyalkylene glycols (alkylene group having 2 to 4 carbon atoms, degree of polymerization 2 to 50), polyoxyalkylene polyols [polyoxyalkylene ethers of the above tri- to octahydric alcohols (alkylene group having 2 to 4 carbon atoms, degree of polymerization 2 to 100)], and mono(meth)acrylates of alkyl (carbon number 1 to 4) ethers of polyoxyalkylene glycols or polyoxyalkylene polyols [polyethylene glycol (Mn: 100 to 300) mono(meth)acrylate, polypropylene glycol (Mn: 130 to 500) mono(meth)acrylate, methoxypolyethylene glycol (Mn: 110 to 310) (meth)acrylate, lauryl alcohol ethylene oxide adduct (2 to 30 mol) (meth)acrylate, and polyoxyethylene (Mn: 150 to 230) sorbitan mono(meth)acrylate].

[0029] Of the monomers (g), hydroxyalkyl (meth)acrylates (having 2 to 6 carbon atoms) are preferred, and hydroxyalkyl (meth)acrylates (having 2 to 4 carbon atoms) are more preferred. The monomer (g) may be used alone or in combination of two or more.

[0030] Examples of the phosphorus atom-containing monomer (h) include the following monomers (h1) to (h2). Phosphate ester group-containing monomer (h1): Examples include (meth)acryloyloxy alkyl (C2-4) phosphate esters [(meth)acryloyloxyethyl phosphate and (meth)acryloyloxyisopropyl phosphate] and alkenyl phosphate esters [vinyl phosphate, allyl phosphate, propenyl phosphate, isopropenyl phosphate, butenyl phosphate, pentenyl phosphate, octenyl phosphate, decenyl phosphate, dodecenyl phosphate, etc.]. Note that "(meth)acryloyloxy" means acryloyloxy or methacryloyloxy.

[0031] Phosphono group-containing monomer (h2): Examples thereof include (meth)acryloyloxyalkyl (C2-4) phosphonic acids [(meth)acryloyloxyethyl phosphonic acid, etc.] and alkenyl (C2-12) phosphonic acids [vinyl phosphonic acid, allyl phosphonic acid, octenyl phosphonic acid, etc.].

[0032] Among (h), (h1) is preferred, (meth)acryloyloxyalkyl (having 2 to 4 carbon atoms) phosphate ester is more preferred, and (meth)acryloyloxyethyl phosphate is particularly preferred. The monomer (h) may be used alone or in combination of two or more.

[0033] Aromatic ring-containing vinyl monomer (i): Examples include styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, 4-crotylbenzene, indene, and 2-vinylnaphthalene. The monomer (i) may be used alone or in combination of two or more.

[0034] Examples of the monomer (j) having two or more unsaturated groups include divinylbenzene, alkadienes having 4 to 12 carbon atoms (such as butadiene, isoprene, 1,4-pentadiene, 1,6-heptadiene, and 1,7-octadiene), (di)cyclopentadiene, vinylcyclohexene, and ethylidenebicycloheptene, limonene, ethylene di(meth)acrylate, polyalkylene oxide glycol di(meth)acrylate, pentaerythritol triallyl ether, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, and esters of unsaturated carboxylic acids and glycols and unsaturated alcohols and carboxylic acids having an Mn of 500 or more, as described in International Publication WO 01 / 009242. The monomer (j) may be used alone or in combination of two or more.

[0035] Vinyl esters, vinyl ethers, vinyl ketones (k): Examples include vinyl esters of saturated fatty acids having 2 to 12 carbon atoms (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octanoate, etc.), alkyl, aryl, or alkoxyalkyl vinyl ethers having 1 to 12 carbon atoms (methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, phenyl vinyl ether, vinyl-2-methoxyethyl ether, vinyl-2-butoxyethyl ether, etc.), and alkyl or aryl vinyl ketones having 1 to 8 carbon atoms (methyl vinyl ketone, ethyl vinyl ketone, phenyl vinyl ketone, etc.). The monomer (k) may be used alone or in combination of two or more.

[0036] Epoxy group-containing monomer (l): Examples include glycidyl (meth)acrylate and glycidyl (meth)allyl ether. The monomer (l) may be used alone or in combination of two or more.

[0037] Halogen-containing monomers (m): Examples include vinyl chloride, vinyl bromide, vinylidene chloride, (meth)allyl chloride, and halogenated styrenes (such as dichlorostyrene). The monomer (m) may be used alone or in combination of two or more.

[0038] Esters of unsaturated polycarboxylic acids (n): Examples include alkyl, cycloalkyl, or aralkyl esters of unsaturated polycarboxylic acids [C1-8 alkyl diesters of unsaturated dicarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.) (dimethyl maleate, dimethyl fumarate, diethyl maleate, and dioctyl maleate)]. The monomer (n) may be used alone or in combination of two or more.

[0039] An ester (o) (monomer (o)) of an alcohol having 1 to 36 carbon atoms to which an alkylene oxide (preferably C2 to C4) is added (preferably 1 to 20 moles) and (meth)acrylic acid. In the monomer (o), examples of the alcohol having 1 to 36 carbon atoms include linear alcohols (methanol, ethanol, n-propanol, n-dodecyl alcohol, n-octadecyl alcohol, n-triacontyl alcohol, etc.) and branched alcohols having 3 to 36 carbon atoms (isopropanol, isobutanol, etc.). Examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide. One type of alkylene oxide may be used, or two or more types may be used in combination. When two or more types are used in combination, they may be added in a block or random manner.

[0040] In the present invention, the weight proportion of the monomer (a) in the constituent monomers of the copolymer (A) is preferably 4.8 to 20% by weight, more preferably 5 to 20% by weight, and particularly preferably 10 to 16.7% by weight, based on the total weight of the constituent monomers of the copolymer (A), from the viewpoints of electrical conductivity and oil solubility. In the present invention, the weight proportion of the monomer (b) in the constituent monomers of the copolymer (A) is preferably 80 to 95.2% by weight, more preferably 80 to 95% by weight, and particularly preferably 83.3 to 90% by weight, based on the total weight of the constituent monomers of the copolymer (A), from the viewpoint of oil solubility. In the present invention, the total weight proportion of the monomers (a) and (b) in the constituent monomers of copolymer (A) is, from the viewpoints of electrical conductivity and oil solubility, preferably 55% by weight or more, more preferably 80% by weight or more, next more preferably 90% by weight or more, and particularly preferably 95% by weight or more, based on the total weight of the constituent monomers of copolymer (A). In the present invention, the weight proportion of the monomer (d) in the constituent monomers of the copolymer (A) is preferably 20% by weight or less, more preferably 10% by weight or less, and particularly preferably 5% by weight or less, based on the total weight of the constituent monomers of the copolymer (A), from the viewpoint of oil solubility. In the present invention, the weight proportion of the monomer (e) in the constituent monomers of the copolymer (A) is, from the viewpoint of oil solubility, preferably 45% by weight or less, more preferably 20% by weight or less, next more preferably 10% by weight or less, and particularly preferably 5% by weight or less, based on the total weight of the constituent monomers of the copolymer (A). In the present invention, the total weight proportion of the monomers (d) to (e) in the constituent monomers of copolymer (A) is, from the viewpoint of oil solubility, preferably 45% by weight or less, more preferably 20% by weight or less, next more preferably 10% by weight or less, and particularly preferably 5% by weight or less, based on the total weight of the constituent monomers of copolymer (A). In the present invention, the weight proportion of the monomer (f) in the constituent monomers of the copolymer (A) is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 3% by weight or less, based on the total weight of the constituent monomers of the copolymer (A), from the viewpoints of oil solubility and electrical conductivity. In the present invention, the weight proportion of the monomer (g) in the constituent monomers of the copolymer (A) is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 3% by weight or less, based on the total weight of the constituent monomers of the copolymer (A), from the viewpoints of oil solubility and electrical conductivity. In the present invention, the weight proportion of the monomer (h) in the constituent monomers of the copolymer (A) is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 3% by weight or less, based on the total weight of the constituent monomers of the copolymer (A), from the viewpoints of oil solubility and electrical conductivity. In the present invention, the total weight proportion of the monomers (f) to (h) in the constituent monomers of copolymer (A) is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 3% by weight or less, based on the total weight of the constituent monomers of copolymer (A), from the viewpoints of oil solubility and electrical conductivity. In the present invention, the total weight proportion of the monomers (i) to (o) in the constituent monomers of copolymer (A) is, from the viewpoints of oil solubility and electrical conductivity, preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 3% by weight or less, based on the total weight of the constituent monomers of copolymer (A).

[0041] In the present invention, the weight ratio (b / a) of the monomer (b) to the weight of the monomer (a) among the monomers constituting the copolymer (A) is 4 to 20. If the weight ratio (b / a) is less than 4, the oil solubility is poor, and if it exceeds 20, the conductivity is poor. The weight ratio (b / a) is preferably 4 to 19, and more preferably 6 to 9, from the viewpoints of oil solubility and electrical conductivity.

[0042] In the present invention, when the copolymer (A) contains the monomers (d) and (e) as constituent monomers, the molar average carbon number of the alkyl groups relative to the total number of moles of the monomers (b), (d) and (e) is preferably 8 to 20, more preferably 10 to 20, from the viewpoints of preventing sedimentation, preventing a decrease in electrical conductivity and oil solubility.

[0043] In the present invention, the concentration of nitrogen atoms derived from the monomer (a) in the copolymer (A) is preferably 0.3 to 1.5% by weight, more preferably 0.7 to 1.3% by weight, from the viewpoints of solubility and conductivity. The nitrogen atom concentration can be calculated using the types and amounts of the monomers used in producing the copolymer (A).

[0044] In the present invention, the concentration of chlorine atoms derived from the monomer (a) in the copolymer (A) is preferably 0.8 to 4.0% by weight, more preferably 1.5 to 3.5% by weight, from the viewpoints of solubility and conductivity. The chlorine atom concentration can be calculated using the types and amounts of the monomers used in producing the copolymer (A).

[0045] In the present invention, the copolymer (A) can be obtained by a known production method, for example, by radically polymerizing a monomer component containing the monomer (a) and the monomer (b), and, if necessary, the above-mentioned monomers (d) to (o), in a solvent in the presence of a polymerization catalyst.

[0046] Examples of solvents that can be used in producing the copolymer (A) include aromatic solvents such as toluene, xylene, and alkylbenzenes having 9 to 10 carbon atoms; aliphatic hydrocarbons (having 6 to 18 carbon atoms) such as n-hexane, n-heptane, cyclohexane, and octane; alcoholic solvents (having 3 to 8 carbon atoms) such as isopropanol, 2-propanol, 1-butanol, and 2-butanol; ether solvents such as tetrahydrofuran; ketone solvents such as methyl ethyl ketone; ester solvents such as ethyl acetate and butyl acetate; and base oils (for example, mineral oils).

[0047] Examples of the polymerization catalyst that can be used include azo catalysts [e.g., 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobisisobutyrate, etc.], and peroxide catalysts [e.g., t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxyneoheptanoate, t-butyl peroxyneodecanoate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxyisobutyrate, t-amyl peroxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexanoate, dibutyl peroxytrimethyladipate, benzoyl peroxide, cumyl peroxide, lauryl peroxide, etc.].

[0048] Furthermore, if necessary, a chain transfer agent [for example, alkyl (having 2 to 20 carbon atoms) mercaptan, etc.] can also be used. The reaction temperature is preferably 50 to 140°C, more preferably 60 to 130°C. In addition to the above solution polymerization, the copolymer (A) can also be obtained by bulk polymerization, emulsion polymerization, or suspension polymerization. The polymerization mode of the copolymer (A) may be either random addition polymerization or alternating copolymerization, or may be either graft copolymerization or block copolymerization.

[0049] The conductive agent of the present invention is only required to contain the copolymer (A), and may contain carbon black (such as acetylene black), carbon nanotubes, ionic liquids, and the like in addition to the copolymer (A).

[0050] From the viewpoint of handling properties, the conductive agent of the present invention may contain a base oil (B) and / or a solvent (C). Examples of the base oil (B) include mineral oils (solvent refined oils, paraffin oils, high viscosity index oils containing isoparaffins, high viscosity index oils obtained by hydrocracking isoparaffins, and naphthenic oils), synthetic lubricating oils (hydrocarbon synthetic lubricating oils (poly-α-olefin synthetic lubricating oils, etc.) and ester synthetic lubricating oils (hereinafter sometimes referred to as ester oils), and mixtures thereof. Among these, ester synthetic lubricating oils are preferred from the viewpoint of electrical conductivity. The solvent (C) includes those exemplified as solvents for producing the copolymer (A), and isopropanol, ethanol, ethyl acetate, methyl ethyl ketone and tetrahydrofuran are preferred in view of versatility and solubility.

[0051] When the conductive agent contains a base oil (B) and / or a solvent (C), the content of the copolymer (A) in the conductive agent is preferably 1 to 90% by weight, more preferably 40 to 80% by weight, from the viewpoints of conductivity and solubility. When the conductive agent contains a base oil (B) and / or a solvent (C), the total content of the base oil (B) and the solvent (C) in the conductive agent is preferably 10 to 99% by weight, more preferably 20 to 60% by weight, from the viewpoints of conductivity and solubility.

[0052] The conductive agent of the present invention has excellent conductivity and oil solubility, and therefore can be used as a conductive agent for imparting conductivity to lubricants such as greases and lubricating oils, etc. In particular, it is suitable as a conductive agent for imparting conductivity to greases used in bearings or sliding parts around electrified parts of various internal combustion engines and machine tools. Furthermore, since the conductive agent of the present invention can be dissolved in solvent (C), it can be applied to a substrate as a coating and used as a conductive agent for imparting conductivity. Furthermore, since a film can be easily formed by application, it is suitable as a conductive coating or an antistatic coating, and can be applied to conductive functional materials, and is also useful as an antistatic film, an electromagnetic wave shielding material, a conductive adhesive, a conductive paint, and a wiring material.

[0053] The lubricant composition of the present invention contains the conductive agent of the present invention and a base oil (B). Examples of the base oil (B) include those described above. Among these, from the viewpoints of conductivity and solubility, base oils and / or ester oils of API Group I to IV are preferred, and ester oils are more preferred. Base oils classified by the American Petroleum Institute (API) (herein referred to as "API classification") as Group I are mineral base oils having a sulfur content of more than 0.03% by mass, a saturated content (saturated hydrocarbons) of less than 90% by volume, and a viscosity index of 80 to less than 120. Base oils classified by API as Group II are mineral base oils having a sulfur content of 0.03% by mass or less, a saturated content (saturated hydrocarbons) of 90% by volume or more, and a viscosity index of 80 to less than 120. Base oils classified by API as Group III are mineral base oils having a sulfur content of 0.03% by mass or less, a saturated content (saturated hydrocarbons) of 90% by volume or more, and a viscosity index of 120 or more. Base oils classified by API as Group IV are poly-alphaolefins. The SP value of the base oil (B) is preferably 7.0 to 11.0 (cal / cm 3 ) from the viewpoint of the solubility of the copolymer (A) in the base oil. 3 ) 1 / 2 and more preferably 7.5 to 10.5 (cal / cm 3 ) 1 / 2 , and particularly preferably 8.0 to 10.0 (cal / cm 3 ) 1 / 2 and most preferably 8.0 to 9.8 (cal / cm 3 ) 1 / 2 is.

[0054] The content of the copolymer (A) in the lubricant composition is preferably 0.1 to 20% by weight, more preferably 1 to 15% by weight, from the viewpoint of electrical conductivity. The content of the base oil (B) in the lubricant composition is preferably 80 to 99.9% by weight, more preferably 85 to 99% by weight, from the viewpoint of electrical conductivity.

[0055] The volume resistivity (25°C) of the lubricant composition is 1.0 x 10 10 Ω·cm or less is preferable.

[0056] The lubricant composition of the present invention may contain a thickener. A lubricant composition containing a thickener is sometimes called a grease. The type of thickener is not particularly limited, and thickeners commonly used in greases can be used without any problems. For example, soaps (including metal salts of fatty acids having 8 to 32 carbon atoms (saturated linear fatty acids, unsaturated linear fatty acids, saturated branched fatty acids, unsaturated branched fatty acids, etc.), specifically metal soaps such as aluminum soap, barium soap, calcium soap, lithium soap, and sodium soap, metal complex soaps such as lithium complex soap, calcium complex soap, and aluminum complex soap), urea compounds such as diurea, triurea, tetraurea, and polyurea, and inorganic compounds such as silica gel and bentonite can also be suitably used. Furthermore, urethane compounds, urea-urethane compounds, sodium terephthalamate, etc. can also be suitably used. These thickeners can be used alone or in combination. From the viewpoint of consistency, the content of the thickener is preferably 5 to 25% by weight, more preferably 10 to 20% by weight, based on the weight of the lubricant composition.

[0057] The lubricant composition of the present invention may further contain, if necessary, an antioxidant, a rust inhibitor, a corrosion inhibitor, an extreme pressure agent, an oiliness agent, a solid lubricant, and the like.

[0058] Examples of antioxidants include phenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and 4,4'-methylenebis(2,6-di-tert-butylphenol), and amine-based antioxidants such as alkyldiphenylamines (wherein the alkyl group has 4 to 20 carbon atoms), triphenylamine, phenyl-α-naphthylamine, phenothiazine, alkylated phenyl-α-naphthylamine, phenithiazine, and alkylated phenothiazine. These can be used alone or in combination of two or more.

[0059] Examples of the rust inhibitor include fatty acid soap, alkyl sulfonate, fatty acid amine, oxidized paraffin, polyoxyethylene alkyl ether, etc. These can be used alone or in combination of two or more.

[0060] Examples of corrosion inhibitors include benzotriazole, benzimidazole, thiadiazole, etc. These can be used alone or in combination of two or more.

[0061] Examples of extreme pressure agents include phosphorus-based compounds such as phosphate esters, phosphites, and phosphate amine salts; sulfur-based compounds such as sulfides and disulfides; chlorine-based compounds such as chlorinated paraffins and chlorinated diphenyls; zinc dialkyldithiophosphates; and organometallic compounds such as molybdenum dialkyldithiocarbamates.

[0062] Examples of oily agents include higher alcohols, polyhydric alcohols, polyhydric alcohol esters, aliphatic esters, aliphatic amines, fatty acid monoglycerides, etc. These can be used alone or in combination of two or more.

[0063] Examples of solid lubricants include molybdenum disulfide, boron nitride, silane nitride, etc. These may be used alone or in combination of two or more.

[0064] Only one of these additives may be added, or two or more additives may be added as needed. The content of each of these additives is preferably 0.1 to 15% by weight based on the total weight of the lubricant composition, and the total content of the additives is preferably 0.1 to 30% by weight, more preferably 0.1 to 10% by weight, based on the total weight of the lubricant composition.

[0065] The lubricant composition of the present invention is free from sedimentation of the conductive agent over time and exhibits little decrease in conductivity, making it particularly suitable as a conductive agent for imparting conductivity to greases used in bearings or sliding parts around electrically charged parts of various internal combustion engines, machine tools, etc. Furthermore, since a coating can be easily formed by application, the composition is suitable for conductive coatings and antistatic coatings, and is also useful as antistatic films, electromagnetic wave shielding materials, conductive adhesives, conductive paints, and wiring materials. [Example]

[0066] The present invention will be further explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0067] Example 1 [Manufacturing of conductive materials] 25 parts by weight of isopropanol was added to a reaction vessel equipped with a stirrer, heating / cooling device, thermometer, dropping funnel, and nitrogen inlet tube. A total of 100 parts by weight of a monomer blend (5 parts by weight of monomer (a-1) [2-methacryloyloxyethyltrimethylammonium chloride], 95 parts by weight of monomer (b-2) [dodecyl acrylate]) was added to a separate glass beaker, along with 25 parts by weight of isopropanol as a polymerization solvent and 0.2 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) as a polymerization catalyst. The mixture was stirred and mixed at 20°C to prepare a monomer solution, which was then placed in the dropping funnel. After nitrogen substitution (gas phase oxygen concentration 100 ppm), the mixture was sealed and heated to 76°C with stirring, and the monomer was added dropwise over 3 hours. The polymerization reaction was carried out at the same temperature for 2 hours. After heating to 90°C, the mixture was aged for 2 hours, and then heated to 120°C. After that, the unreacted monomer and isopropanol were removed at the same temperature under reduced pressure (0.027 to 0.040 MPa) over 1 hour to obtain a conductive agent (R-1) containing copolymer (A-1).

[0068] <Examples 2 to 11 and Comparative Examples 1 to 6> Conductive agents (R-2) to (R-11) or (R'-1) to (R'-4) containing copolymers (A-2) to (A-11) or (A'-1) to (A'-4) were obtained in the same manner as in Example 1, except that the monomer blend was changed to that shown in Table 1. In Comparative Example 5, an ionic liquid (1-ethyl-3-methylimidazolium monomethyl carbonate) was used as the conductive agent (R'-5), and in Comparative Example 6, carbon black (manufactured by Kao Corporation, product name "Ketjenblack EC300J") was used as the conductive agent (R'-6).

[0069] The compositions of the monomer (a), the monomer (b), the base oil (B), and the solvent (C) shown in Table 1 are as follows: (a-1): 2-methacryloyloxyethyltrimethylammonium chloride (a-2): N-benzyl-N,N-dimethyl-2-(methacryloyloxy)ethylammonium chloride (b-1): 2-ethylhexyl acrylate (b-2): Dodecyl acrylate (b-3): Tetradecyl acrylate (b-4): Tetradecyl methacrylate (d-1): Hexyl acrylate (e-1): Hexadecyl methacrylate (e-2): Hexadecyl acrylate (e-1): 2-n-tetradecyl octadecyl methacrylate (B-1): Mineral oil (SK Lubricants YUBASE4) (B-2): Hydrocarbon synthetic oil (Spectrasyn 4 manufactured by Exxon Mobil) (B-3): Diester of 2-ethylhexyl alcohol and sebacic acid (C-1): Ethyl acetate (C-2): Tetrahydrofuran

[0070] [Table 1]

[0071] <Compatibility of copolymer (A) with base oil> Conductive agents (R-1) to (R-11) or (R'-1) to (R'-4) were mixed with base oil (B) or solvent (C) to prepare solutions in which the concentration of conductive agent (R) or (R') was adjusted to the following concentrations. The appearance was visually observed, and the compatibility with base oil (B) or solvent (C) was evaluated according to the following evaluation criteria. [Evaluation criteria] ◎: In a solution with a conductive agent concentration of 10% by weight, the appearance is uniform and there is no insoluble conductive agent. ○: In a solution with a 5% by weight concentration of conductive agent, the appearance is uniform and there is no insoluble conductive agent, but in a solution with a 10% by weight concentration of conductive agent, the appearance is non-uniform and unnecessary conductive agent particles are found. ×: In a solution with a 5% by weight concentration of conductive agent, the appearance was uneven and insoluble conductive agent was observed.

[0072] <Initial volume resistivity (initial volume resistivity) of lubricant composition using base oil (B-3)> Conductive agents (R-1) to (R-11) or (R'-1) to (R'-6) were dissolved or dispersed in base oil (B-3) so that the concentration of the conductive agent was 5% by weight, and the volume resistivity was measured at 25°C in accordance with JIS C 2101, Section 24 (Volume Resistivity Test). In order for the lubricant composition to maintain conductivity and exhibit its performance, the volume resistivity must be 1.0 x 10 10 It is desirable that the resistance be Ω·cm or less.

[0073] <Stability test> A stability test was conducted on the lubricant composition using base oil (B-3) under the following conditions using a tester equipped with a rotating device, and the volume resistivity (Ω·cm) and appearance were checked 200 hours, 400 hours, and 800 hours after the start of the stability test. The appearance was evaluated according to the following criteria. [Test conditions] Temperature: 130℃ Load (load): Fr = 1960N (200kgf) Rotation speed: 100 times per minute [Evaluation criteria] ◯: The appearance is uniform and there is no sedimentation of the conductive agent. ×: The appearance is uneven and sedimentation of the conductive agent is observed.

[0074] The results of Examples 1 to 11 show that the conductive agent of the present invention has high solubility in solvents and base oils. On the other hand, the conductive agents of Comparative Examples 1 and 2, in which the copolymer does not contain monomer (b) as a constituent monomer, have low solubility in base oils and solvents. Furthermore, Comparative Example 3, in which the weight ratio (b / a) of the monomers is outside the lower limit range, also has low solubility in solvents and base oils. Furthermore, Comparative Example 4, in which the weight ratio (b / a) of the monomers is outside the upper limit range, has high solubility but low conductivity. [Industrial Applicability]

[0075] The conductive agent of the present invention is highly soluble in solvents and base oils, does not settle over time, and exhibits minimal loss of conductivity. It can be used as a conductive agent for imparting conductivity to lubricants such as greases and lubricating oils. It is particularly suitable as a conductive agent for imparting conductivity to greases used in bearings or sliding parts around electrically charged parts of various internal combustion engines and machine tools. The lubricant composition of the present invention can also be suitably used as a grease or lubricating oil, and is particularly useful as a grease for applications requiring antistatic properties, such as bearings (e.g., rolling bearings) or sliding parts around electrically charged parts of internal combustion engines and machine tools. Furthermore, since a film can be easily formed by application, it is suitable for conductive coatings and antistatic coatings, and is also useful as an antistatic film, an electromagnetic wave shielding material, a conductive adhesive, a conductive paint, and a wiring material.

Claims

1. A conductive agent containing a copolymer (A) having, as essential constituent monomers, a monomer (a) represented by the following general formula (1) and a (meth)acrylic acid alkyl ester monomer (b) having an alkyl group having 8 to 14 carbon atoms, wherein, in the monomers constituting the copolymer (A), the weight ratio (b / a) of the monomer (b) to the weight of the monomer (a) is 4 to 20: 【Chemistry 1】 [In formula (1), R １ ~R ３ each independently represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom; -X- represents a group represented by -O- or -NH-; Q represents an alkylene group having 1 to 4 carbon atoms; Z － represents a residue obtained by removing a proton from a protonic acid.

2. 2. The conductive agent according to claim 1, wherein the weight ratio of the monomer (a) based on the weight of the constituent monomers of the copolymer (A) is 0.1 to 30% by weight.

3. A lubricant composition comprising the conductive agent according to claim 1 or 2 and a base oil (B).

4. 4. The lubricant composition according to claim 3, wherein the base oil (B) is a base oil and / or an ester oil of API Group I to IV.

5. 4. The lubricant composition according to claim 3, wherein the content of said copolymer (A) is 0.1 to 20% by weight based on the weight of the lubricant composition.

6. The lubricant composition according to claim 3, further comprising a thickener.

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