Lubricant composition and grease

Abstract

To provide a lubricant composition and grease that have excellent storage stability and high friction reduction effect. [Solution] A lubricant composition comprising a polymer block (A) having the structure of the following formula (1), a copolymer (C) having a (meth)acrylic polymer block (B), and a silicone oil. [C1] TIFF2026083996000008.tif35170 (however, in formula (1), R 1 These are alkyl groups, alkenyl groups, aryl groups, alkylaryl groups, arylalkyl groups, alkyl groups containing a fluorine atom, alkenyl groups containing a fluorine atom, aryl groups containing a fluorine atom, alkylaryl groups containing a fluorine atom, or arylalkyl groups containing a fluorine atom. 1 They may be the same or different.

Description

[Technical Field]

[0001] This invention relates to lubricant compositions and greases. [Background technology]

[0002] Lubricants, such as those found in automobile engine oil and drivetrain fluids, contain various friction-reducing agents to reduce energy loss due to friction and extend the lifespan of equipment by preventing seizing. In recent years, with the trend towards lower viscosity lubricants aimed at improving fuel efficiency, the load on metal-to-metal contact surfaces has become more severe, making the role of friction-reducing agents even more crucial.

[0003] Silicone oil has a high viscosity index and its viscosity does not easily increase even at low temperatures, so it can be used as a base oil over a wide temperature range. As a lubricant composition using silicone oil, for example, Patent Document 1 discloses a lubricant composition obtained by dissolving a silicone oil having a specific kinematic viscosity with a mineral oil-based and / or wax isomerized base oil. Patent Document 2 discloses a lubricant composition containing 0.01 to 30% by mass of silicone oil. Patent Document 3 discloses a grease composition containing an aryl group-containing polyorganosiloxane and an acrylic block copolymer having a weight-average molecular weight of 10,000 to 1,000,000 and a molecular weight distribution (Mw / Mn) of 1.5 or less. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2012-207082 [Patent Document 2] Japanese Patent Publication No. 2005-8737 [Patent Document 3] International Publication No. 2017 / 175653 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, conventional lubricant compositions such as those described in Patent Documents 1-3 have insufficient friction reduction effects. The main object of the present invention is to provide a lubricant composition and grease that have excellent storage stability and high friction reduction effect. [Means for solving the problem]

[0006] The present invention includes the following configuration. [1]: A lubricant composition comprising a polymer block (A) having the structure of the following formula (1), a copolymer (C) having a (meth)acrylic polymer block (B), and a silicone oil. [ka] (However, in equation (1), R 1 These are alkyl groups, alkenyl groups, aryl groups, alkylaryl groups, arylalkyl groups, alkyl groups containing a fluorine atom, alkenyl groups containing a fluorine atom, aryl groups containing a fluorine atom, alkylaryl groups containing a fluorine atom, or arylalkyl groups containing a fluorine atom. 1 These may be the same group or different groups. [2]: The lubricant composition according to [1], wherein the (meth)acrylic polymer block (B) comprises a constituent unit derived from alkyl (meth)acrylate having an alkyl group having 1 to 30 carbon atoms. [3]: The lubricant composition according to [1] or [2], wherein the number average molecular weight of the polymer block (A) is 500 to 100,000. [4]: The lubricant composition according to [1] or [2], wherein the number average molecular weight of the polymer block (A) is 2,000 to 100,000. [5]: The lubricant composition according to any one of [1] to [4], wherein the content of the polymer block (A) in the copolymer (C) is 5 to 90% by mass relative to the total mass of the copolymer (C). [6]: The lubricant composition according to any one of [1] to [5], wherein the weight-average molecular weight of the copolymer (C) is 10,000 to 1,000,000. [7]: The lubricant composition according to any one of [1] to [6], wherein the kinematic viscosity at 40 °C when the copolymer (C) is contained at 2% by mass is 10 to 500 cSt. [8]: The lubricant composition according to any one of [1] to [7], wherein the copolymer (C) is a friction reducer. [9]: Grease containing the lubricant composition according to any one of [1] to [8] and a thickener. [Advantages of the Invention]

[0007] According to the present invention, there are provided a lubricant composition excellent in storage stability and having a high friction reduction effect, and grease. [Embodiments for Carrying Out the Invention]

[0008] Hereinafter, the present invention will be described in detail. The following embodiments are merely examples for explaining the present invention, and it is not intended to limit the present invention only to these embodiments. The present invention can be implemented in various modes without departing from the gist thereof. In the present specification and claims, the numerical range represented by "~" means a numerical range including the numerical values before and after ~ as the lower limit value and the upper limit value. For example, A~B is synonymous with A or more and B or less. The numerical ranges of the contents, various physical property values, and property values disclosed in the present specification can be combined arbitrarily with the lower limit value and the upper limit value to form a new numerical range.

[0009] In the present invention and the present specification, the following terms have the following meanings. "Structural unit" means a unit constituting a polymer derived from a monomer, that is, a structural unit formed by polymerization of a monomer, or a structural unit in which a part of the structural unit is converted into another structure by subjecting the polymer to a modification treatment. "(Meth)acryl" is a general term for "acryl" and "methacryl". "(Meth)acrylate" is a general term for "acrylate" and "methacrylate". The "(meth)acryloyl group" is a general term for the "acryloyl group" and the "methacryloyl group", and is a group represented by CH2=C(R')-C(=O)- (where R' is a hydrogen atom or a methyl group). The "(meth)acryloyloxy group" is a general term for the "acryloyloxy group" and the "methacryloyloxy group", and is a group represented by CH2=C(R')-C(=O)-O- (where R' is a hydrogen atom or a methyl group). The "macromonomer" means a polymer having a radically polymerizable group or an addition-reactive functional group. The "radically polymerizable monomer" means a monomer having an ethylenically unsaturated bond that is not a macromonomer. The "graft copolymer" is a polymer having one or more blocks chemically bonded as a side-chain polymer structure (branched polymer structure) to a main-chain polymer structure (trunk polymer structure). The "weight-average molecular weight" and the "number-average molecular weight" each mean the weight-average molecular weight or the number-average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC).

[0010] [Lubricant Composition] The lubricant composition according to the embodiment includes a copolymer (C) and a silicone oil.

[0011] (Copolymer (C)) The copolymer (C) is a copolymer containing a polymer block (A) and a (meth)acrylic polymer block (B). The copolymer (C) may be a block copolymer or a graft copolymer. From the viewpoint of better reducing the friction, the copolymer (C) is preferably a graft copolymer.

[0012] The copolymer (C) is preferably a diblock copolymer consisting of a polymer block (A) and a (meth)acrylic polymer block (B); a triblock copolymer in which polymer block (A) and (meth)acrylic polymer block (B) are arranged as (A)-(B)-(A) or (B)-(A)-(B); or a graft copolymer in which polymer block (A) is the side chain and (meth)acrylic polymer block (B) is the main chain. The graft copolymer in which polymer block (A) is the side chain and (meth)acrylic polymer block (B) is the main chain is more preferred because it can provide a better friction reduction effect.

[0013] There are no particular limitations on the method for producing graft copolymers, but examples include a method in which macromonomers having radically polymerizable double bonds at their ends are produced as a side-chain polymer structure, and then radically polymerized together with monomers that will become the constituent units of the main-chain polymer; a method in which a main-chain polymer having reaction sites and macromonomers having reaction sites are produced in advance and then reacted; and a method in which radicals are generated on the main-chain polymer using an initiator with hydrogen abstraction ability after the main-chain polymer is produced, and monomers that will become the constituent units of the side-chain polymer are reacted to produce a side-chain polymer structure.

[0014] <Polymer block (A)> Polymer block (A) contains the structure of formula (1) below, i.e., a polysiloxane structure.

[0015] [ka]

[0016] However, in equation (1), R 1 These are alkyl groups, alkenyl groups, aryl groups, alkylaryl groups, arylalkyl groups, alkyl groups containing a fluorine atom, alkenyl groups containing a fluorine atom, aryl groups containing a fluorine atom, alkylaryl groups containing a fluorine atom, or arylalkyl groups containing a fluorine atom. 1 These elements may be the same base or different bases. n is an integer greater than or equal to 1.

[0017] The alkyl group may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 30, and more preferably 1 to 4. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, octadecyl, behenyl, cetyl, and stearyl groups.

[0018] The alkenyl group may be linear, branched, or cyclic. The number of carbon atoms in the alkenyl group is preferably 2 to 30, and more preferably 2 to 20. Examples of alkenyl groups include linear alkenyl groups or branched alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, methylheptenyl group, nonyl group, methyloctenyl group, decenyl group, methylnonyl group, undecenyl group, methyldecenyl group, dodecenyl group, methylundecenyl group, tridecenyl group, methyldodecenyl group, tetradecenyl group, methyltridecenyl group, pentadecenyl group, methyltetradecenyl group, hexadecenyl group, methylpentadecenyl group, heptadecenyl group, methylhexadecenyl group, octadecenyl group, methylheptadecenyl group, nonadecenyl group, and methyloctadecenyl group.

[0019] The number of carbon atoms in the aryl group is preferably 6 to 30, and more preferably 6 to 12. Examples of aryl groups include phenyl, naphthyl, anthracenyl, biphenyl, and terphenyl groups.

[0020] Examples of alkylaryl groups include methylphenyl, ethylphenyl, isopropylphenyl, tolyl, dimethylphenyl, butylphenyl, nonylphenyl, methylbenzyl, and dimethylnaphthyl groups. Examples of arylalkyl groups include phenylmethyl, phenylethyl, and diphenylmethyl groups.

[0021] Examples of alkyl groups containing a fluorine atom, alkenyl groups containing a fluorine atom, aryl groups containing a fluorine atom, alkylaryl groups containing a fluorine atom, and arylalkyl groups containing a fluorine atom include groups in which one or more hydrogen atoms of the aforementioned alkyl group, alkenyl group, aryl group, alkylaryl group, or arylalkyl group are substituted with fluorine atoms.

[0022] From the standpoint of availability and industrial considerations, R 1 Preferably, alkyl groups, alkenyl groups, aryl groups, alkylaryl groups, and arylalkyl groups are used, more preferably alkyl groups having 1 to 4 carbon atoms and phenyl groups, and even more preferably methyl groups. n is preferably 1 to 500, more preferably 10 to 200, and even more preferably 50 to 150.

[0023] The polymer block (A) preferably contains polymer chains consisting of constituent units derived from a macromonomer (M) represented by the following formula (M1).

[0024] [ka]

[0025] However, in equation (M1), R 2is an alkyl group, alkenyl group, aryl group, alkylaryl group, arylalkyl group, alkyl group containing a fluorine atom, alkenyl group containing a fluorine atom, aryl group containing a fluorine atom, alkylaryl group containing a fluorine atom, or arylalkyl group containing a fluorine atom. Q is an alkylene group, alkenylene group, arylene group, alkylarylene group, arylalkylene group, alkylene group containing a fluorine atom, alkenylene group containing a fluorine atom, arylene group containing a fluorine atom, alkylarylene group containing a fluorine atom, or arylalkylene group containing a fluorine atom, and may contain a carbonyl group, ester bond, amide bond, ether bond, thioether bond, thioester bond, thionoester bond, thioamide bond, or imide bond. X is a radically polymerizable functional group. R 1 is the same as R in formula (1) 1 and a plurality of R 1 may each be the same group or different groups. n is the same as n in formula (1).

[0026] R 2 as the group of, the same groups as those exemplified for R 1 are mentioned. As R 2 from the viewpoint of availability and industrial aspects, an alkyl group is preferable, an alkyl group having 1 to 4 carbon atoms is more preferable, and an n-butyl group is even more preferable.

[0027] The alkylene group of Q may be linear, branched, or cyclic. The number of carbon atoms of the alkylene group is preferably 1 to 10, more preferably 1 to 4. Examples of the alkylene group include a methylene group, ethylene group, propylene group, isopropylene group, n-butylene group, isobutylene group, t-butylene group, pentylene group, and hexylene group, and a propylene group is more preferable.

[0028] The alkenylene group may be linear, branched, or cyclic.[[ID=​ Examples of alkenylene groups include propynylene, butynylene, pentynylene, and hexynylene.

[0029] The number of carbon atoms in the arylene group is preferably 6 to 30, and more preferably 6 to 12. Examples of allylene groups include phenylene groups, biphenylene groups, terphenylene groups, naphthylene groups, and anthracenylene groups.

[0030] Examples of alkylarylene groups include methylphenylene group, ethylphenylene group, t-butylphenylene group, methylnaphthylene group, ethylnaphthylene group, and t-butylnaphthylene group. Examples of arylalkylene groups include phenylmethylene, phenylethylene, phenylpropylene, and phenylbutylene.

[0031] Examples of alkylene groups containing fluorine atoms, alkenylene groups containing fluorine atoms, arylene groups containing fluorine atoms, alkylarylene groups containing fluorine atoms, and arylalkylene groups containing fluorine atoms include groups in which one or more hydrogen atoms of the aforementioned alkylene group, alkenylene group, arylene group, alkylarylene group, and arylalkylene group are substituted with fluorine atoms.

[0032] From the standpoint of availability and industrial considerations, alkylene groups are preferred for Q, alkylene groups having 1 to 4 carbon atoms are more preferred, and propylene groups are even more preferred.

[0033] The radical polymerizable functional group of X is preferably a (meth)acryloyl group, a (meth)acryloyloxy group, or a vinyl group, with (meth)acryloyl group and (meth)acryloyloxy group being more preferred.

[0034] The macromonomer (M1) may be one that has been prepared by a known method, or one that is commercially available.

[0035] The number-average molecular weight of polymer block (A) is preferably 500 or more, more preferably 1000 or more, even more preferably 2000 or more, and particularly preferably 4000 or more. If the number-average molecular weight of polymer block (A) is above the lower limit, the solubility in silicone oil is improved. The number-average molecular weight of polymer block (A) is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 20,000 or less, and particularly preferably 8,000 or less. If the number-average molecular weight of polymer block (A) is below the upper limit, the friction reduction performance is improved. The preferred lower and upper limits for the number-average molecular weight of polymer block (A) can be arbitrarily combined.

[0036] The content of polymer blocks (A) in copolymer (C) is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more, based on the total mass of copolymer (C). If the content of polymer blocks (A) is above the lower limit, the solubility in silicone oil is improved. The content of polymer blocks (A) in copolymer (C) is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 60% by mass or less, based on the total mass of copolymer (C). If the content of polymer blocks (A) is below the upper limit, the friction reduction performance is improved. The preferred lower and upper limits for the content of polymer blocks (A) can be arbitrarily combined.

[0037] <(Meth)acrylic polymer block (B)> The (meth)acrylic polymer block (B) is composed of polymer chains containing constituent units derived from the (meth)acrylic polymer, i.e., the (meth)acrylic monomer (m1). The (meth)acrylic polymer may also contain constituent units derived from other radical polymerizable monomers (m2) other than the (meth)acrylic monomer (m1).

[0038] The (meth)acrylic monomer (m1) is a radical polymerizable monomer having a (meth)acryloyl group. As the (meth)acrylic monomer (m1), an alkyl (meth)acrylate having an alkyl group with 1 to 30 carbon atoms (hereinafter also referred to as "monomer (m11)") is preferred. Examples of monomers (m11) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, and n-dodecyl (meth)acrylate. (meth)acrylates having linear alkyl groups such as n-tridecyl(meth)acrylate, n-tetradecyl(meth)acrylate, n-pentadecyl(meth)acrylate, n-cetyl(meth)acrylate, n-heptadecyl(meth)acrylate, n-stearyl(meth)acrylate, n-behenyl(meth)acrylate; i-propyl(meth)acrylate, i-butyl(meth)acrylate, t-butyl i-(meth)acrylate, i-nonyl(meth)acrylate, i-decyl(meth)acrylate, i-undecyl(meth)acrylate, i-dodecyl(meth)acrylate, i-tridecyl(meth)acrylate, i-tetradecyl(meth)acrylate, i-pentadecyl(meth)acrylate, i-cetyl(meth)acrylate, i-heptadecyl(meth)acrylate, i-stearyl(meth)acrylate, i-octadecyl(meth)acrylate Examples include alkyl(meth)acrylates having branched alkyl groups such as rilate, i-behenyl(meth)acrylate, and 2-ethylhexyl(meth)acrylate; and alkyl(meth)acrylates having cyclic alkyl groups such as cyclopentyl(meth)acrylate, cyclohexyl(meth)acrylate, dicyclopentanyl(meth)acrylate, isobornyl(meth)acrylate, and 4-t-butylcyclohexyl(meth)acrylate. These monomers (m11) may be used individually or in combination of two or more.

[0039] As monomer (m11), a (meth)acrylate having a linear or branched alkyl group is preferred from the viewpoint of improving solubility in silicone oil and improving friction reduction performance, and it is more preferable to include a (meth)acrylate having a linear or branched alkyl group having 8 to 20 carbon atoms (hereinafter also referred to as "monomer (m12)") and / or a (meth)acrylate having a linear or branched alkyl group having 1 to 7 carbon atoms (hereinafter also referred to as "monomer (m13)"). As monomer (m12), a (meth)acrylate having a linear or branched alkyl group having 10 to 18 carbon atoms is even more preferred, and a (meth)acrylate having a linear or branched alkyl group having 10 to 14 carbon atoms is particularly preferred. As monomer (m13), a (meth)acrylate having a linear or branched alkyl group having 1 to 4 carbon atoms is even more preferred. Either monomer (m12) or monomer (m13) may be used, or both may be used.

[0040] Examples of (meth)acrylic monomers other than monomer (m11) (hereinafter also referred to as "monomer (m14)") include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, ethylene glycol mono(meth)acrylate, and propylene glycol mono(meth)acrylate; (meth)acrylic acid, 2-(meth)acrylophosphate succinate. (Meth)acrylates containing carboxyl groups such as yloxyethyl, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, and 2-(meth)acryloyloxyethyl hexahydrophthalate; phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene (meth)acrylates having an aromatic ring structure such as propyl glycol (meth)acrylate, phenylphenyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, (1-naphthyl)methyl (meth)acrylate; (meth)acrylates having a heterocyclic structure such as tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, (meth)acrylate oil morpholin; methoxyethyl (meth) Examples include acrylates, ethoxyethyl (meth)acrylates, butoxyethyl (meth)acrylates, and other alkoxyalkyl (meth)acrylates; 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, trifluoroethyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and (meth)acrylamide.These monomers (m12) may be used individually or in combination of two or more types.

[0041] The constituent units derived from the (meth)acrylic monomer (m1) contained in the (meth)acrylic polymer block (B) may be one type or two or more types. From the standpoint of improving compatibility with silicone oil and enhancing friction reduction performance, the (meth)acrylic polymer block (B) preferably contains constituent units derived from alkyl (meth)acrylate, and more preferably contains constituent units derived from (meth)acrylate having an alkyl group having 1 to 30 carbon atoms.

[0042] Other examples of radical polymerizable monomers (m2) include the following monomers: Examples include vinyl monomers such as styrene, α-methylstyrene, pt-butylstyrene, vinyltoluene, vinyl chloride, vinyl acetate, and vinyl propionate; carboxyl group-containing vinyl monomers such as crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, and monomethyl itaconic acid; and acid anhydride group-containing vinyl monomers such as maleic anhydride and itaconic anhydride. These other radical polymerizable monomers (m2) may be used individually or in combination of two or more.

[0043] When copolymer (C) is a graft copolymer, copolymer (C) is preferably one in which the main chain contains structural units derived from a (meth)acrylic monomer (m1) and the side chains contain structural units derived from a macromonomer (M1), and copolymer (C) is more preferably one in which the main chain contains structural units derived from a monomer (m11) and the side chains contain structural units derived from a macromonomer (M1).

[0044] The proportion of constituent units derived from (meth)acrylic monomers (m1) in the (meth)acrylic polymer block (B) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the (meth)acrylic polymer block (B). The upper limit of the proportion of constituent units derived from (meth)acrylic monomers (m1) is not particularly limited and can be 100% by mass.

[0045] The proportion of constituent units derived from monomer (m11) in the (meth)acrylic polymer block (B) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the (meth)acrylic polymer block (B). If the proportion of constituent units derived from monomer (m11) is above the lower limit, the compatibility with silicone oil is improved, and the friction reduction performance is improved. The upper limit of the proportion of constituent units derived from monomer (m11) is not particularly limited and can be 100% by mass.

[0046] The proportion of constituent units derived from monomer (m12) in the (meth)acrylic polymer block (B) is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total mass of the (meth)acrylic polymer block (B). If the proportion of constituent units derived from monomer (m12) is above the lower limit, the compatibility with silicone oil is improved. The proportion of constituent units derived from monomer (m12) in the (meth)acrylic polymer block (B) is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, based on the total mass of the (meth)acrylic polymer block (B). If the proportion of constituent units derived from monomer (m12) is below the upper limit, the friction reduction performance is improved. The preferred lower and upper limits for the proportion of constituent units derived from monomer (m12) can be arbitrarily combined.

[0047] The proportion of constituent units derived from monomer (m13) in the (meth)acrylic polymer block (B) is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on the total mass of the (meth)acrylic polymer block (B). If the proportion of constituent units derived from monomer (m13) is above the lower limit, the friction reduction performance is improved. The proportion of constituent units derived from monomer (m13) in the (meth)acrylic polymer block (B) is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 50% by mass or less, based on the total mass of the (meth)acrylic polymer block (B). If the proportion of constituent units derived from monomer (m13) is below the upper limit, the compatibility with silicone oil is improved. The preferred lower and upper limits for the proportion of constituent units derived from monomer (m13) can be arbitrarily combined.

[0048] The proportion of constituent units derived from monomer (m14) in the (meth)acrylic polymer block (B) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, based on the total mass of the (meth)acrylic polymer block (B). If the proportion of constituent units derived from monomer (m14) is above the lower limit, the friction reduction performance is improved. The proportion of constituent units derived from monomer (m14) in the (meth)acrylic polymer block (B) is preferably 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 mass of the (meth)acrylic polymer block (B). If the proportion of constituent units derived from monomer (m14) is below the upper limit, the compatibility with silicone oil is improved. The preferred lower and upper limits for the proportion of constituent units derived from monomer (m14) can be arbitrarily combined.

[0049] The proportion of constituent units derived from other radical polymerizable monomers (m2) in the (meth)acrylic polymer block (B) is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 10% by mass or less, based on the total mass of the (meth)acrylic polymer block (B).

[0050] The weight-average molecular weight of copolymer (C) is preferably 10,000 or more, more preferably 30,000 or more, even more preferably 50,000 or more, and particularly preferably 60,000 or more. If the weight-average molecular weight of copolymer (C) is above the lower limit, the friction reduction performance is improved. The weight-average molecular weight of copolymer (C) is preferably 1,000,000 or less, more preferably 500,000 or less, even more preferably 300,000 or less, and particularly preferably 100,000 or less. If the weight-average molecular weight of copolymer (C) is below the upper limit, the compatibility with silicone oil is improved. The preferred lower and upper limits for the weight-average molecular weight of copolymer (C) can be arbitrarily combined.

[0051] The content of copolymer (C) in the lubricant composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and particularly preferably 2% by mass or more, based on the total mass of the lubricant composition. If the content of copolymer (C) is above the lower limit, the friction reduction performance is improved. The content of copolymer (C) in the composition is preferably 30% by mass or less, more preferably 10% by mass or less, even more preferably 8% by mass or less, and particularly preferably 5% by mass or less, based on the total mass of the lubricant composition. If the content of copolymer (C) is below the upper limit, the compatibility with silicone oil is improved. The preferred lower and upper limits for the content of copolymer (C) can be arbitrarily combined.

[0052] Copolymer (C) can be produced, for example, by polymerizing a monomer mixture containing a (meth)acrylic monomer (m1) and a macromonomer (M1) in a silicone oil; by polymerizing a monomer mixture containing a (meth)acrylic monomer (m1) and a macromonomer (M1) in a volatile organic solvent and dissolving it in a silicone oil by solvent substitution; or by polymerizing a monomer mixture containing a (meth)acrylic monomer (m1) and a macromonomer (M1) without a solvent and then dissolving it in a silicone oil. Silicone oil will be discussed later.

[0053] Polymerization can be carried out under known conditions, but it is preferable to use a chain transfer agent because it is particularly effective in suppressing heat generation during polymerization, and it is preferable to use α-methylstyrene dimer or the like as the chain transfer agent.

[0054] The copolymer (C) described above functions as a friction reducer. It is preferable that the copolymer (C) is dissolved in the silicone oil. Dissolution refers to a state in which it has become a homogeneous solution. It is preferable that the copolymer (C) is not crosslinked with a crosslinking agent or the like, as this improves its solubility in the silicone oil.

[0055] (Silicone oil) The lubricant composition according to this embodiment includes silicone oil. The silicone oil is not particularly limited, and examples include organopolysiloxanes represented by the following formula (2).

[0056] [ka]

[0057] However, in formula (2), R is an alkyl group, an alkenyl group, an aryl group, an alkylaryl group, an aryl alkyl group, an alkyl group containing a fluorine atom, an alkenyl group containing a fluorine atom, an aryl group containing a fluorine atom, an alkylaryl group containing a fluorine atom, or an arylalkyl group containing a fluorine atom. Multiple Rs may be the same group or different groups. m is an integer of 1 or more.

[0058] The basis of R is R in formula (1) above. 1 The same group exemplified above can be used as an example. Specific examples of silicone oils include dimethyl silicone, diphenyl silicone, dimethyl silicate, and trifluoropropyl methyl silicone. As for the silicone oil, one type may be used alone, or two or more types may be used in combination.

[0059] The silicone oil content in the lubricant composition is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and also preferably 99.9% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less, based on the total mass of the lubricant composition. The preferred lower and upper limits of the silicone oil content can be any combination.

[0060] (optional ingredient) The lubricant composition according to the embodiment may contain optional components other than copolymer (C) and silicone oil. For example, the lubricant composition according to this embodiment may contain other base oils in addition to silicone oil. Examples of base oils include mineral-based base oils refined from crude oil and chemically synthesized synthetic oils. For example, these include API Group III base oils such as YUBASE3 from SK Lubricants, API Group III Plus base oils such as YUBASE4 from SK Lubricants, and API Group IV base oils such as polyalphaolefins.

[0061] When a base oil is added, the ratio of the total amount of copolymer (C) and silicone oil in the lubricant composition according to the embodiment is preferably 1 to 99 parts by mass, more preferably 10 to 90 parts by mass, and even more preferably 30 to 70 parts by mass, per 100 parts by mass of base oil.

[0062] Optional components other than base oils include, for example, antioxidants, viscosity index improvers, pour point depressants, detergents, dispersants, corrosion inhibitors, rust inhibitors, defoamers, emulsifiers, fungicides, anti-emulsifiers, colorants, and metal deactivators. As optional ingredients, one type may be used alone, or two or more types may be used in combination.

[0063] The kinematic viscosity at 40°C of a lubricant composition containing 2% by mass of copolymer (C) is preferably 10 cSt or higher, more preferably 18 cSt or higher, even more preferably 20 cSt or higher, particularly preferably 22 cSt or higher, and also preferably 500 cSt or lower, more preferably 100 cSt or lower, even more preferably 50 cSt or lower, and particularly preferably 30 cSt or lower. The lower and upper limits of the kinematic viscosity can be combined arbitrarily. The kinematic viscosity of a lubricant composition at 40°C refers to the kinematic viscosity measured according to the ASTM D7279 (D445) method, with the composition temperature set to 40°C.

[0064] (Method for producing lubricant compositions) The lubricant composition according to this embodiment is obtained by mixing a copolymer (C) and a silicone oil. Furthermore, when copolymer (C) is produced in silicone oil, copolymer (C) is obtained dissolved or dispersed in the silicone oil. The polymer solution containing this copolymer (C) may be used as a composition as is, or optional components may be added to the polymer solution as needed to form a lubricant composition. The polymer solution may also be diluted with silicone oil to form a lubricant composition.

[0065] (Effects and Benefits) The lubricant composition according to this embodiment contains a copolymer (C) and silicone oil, and therefore has a high friction reduction effect and excellent storage stability.

[0066] (Application) The lubricant composition according to this embodiment can be used as a lubricant additive blended into engine oil, drivetrain oil (gear oil, transmission oil), hydraulic oil, metalworking oil, etc., used in mobility such as automobiles and ships, as well as industrial machinery, robots, etc. Examples of additives for lubricating oils include friction reducers such as oiliness improvers, extreme pressure agents, anti-wear agents, and friction modifiers, as well as antioxidants, viscosity index improvers, pour point depressants, detergent dispersants, corrosion inhibitors, rust inhibitors, defoamers, emulsifiers, antifungal agents, and anti-emulsifiers.

[0067] [Grease] The grease according to the embodiment comprises the lubricant composition according to the embodiment described above and a thickener. Examples of thickeners include soap-based materials (lithium soap, calcium soap, sodium soap, aluminum soap, etc.), inorganic materials (bentonite, silica gel, etc.), and organic materials (polyurea, polyurethane, etc.).

[0068] The grease according to this embodiment may contain other additives besides thickeners. Other additives include, for example, antioxidants, viscosity index improvers, pour point depressants, cleaning agents, dispersants, corrosion inhibitors, rust inhibitors, defoamers, emulsifiers, fungicides, and anti-emulsifiers. In addition, other friction-reducing agents besides those embodied in this embodiment may include oiliness enhancers such as long-chain fatty acid esters and fatty acid amides, anti-wear agents such as phosphate esters and zinc dithiophosphate, extreme pressure agents such as organic sulfur compounds and organic halogen compounds, and friction modifiers such as molybdenum dithiocarbamate. [Examples]

[0069] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not exceed the spirit of the invention, and various modifications are possible as long as they do not depart from the spirit of the invention. In the examples, "parts" refers to "parts by mass".

[0070] [Molecular weight of copolymer (C)] The molecular weight of copolymer (C) was measured using gel permeation chromatography (GPC) (manufactured by Tosoh Corporation, product name "HLC-8320"). After preparing a 0.2% by mass solution of copolymer (C) in tetrahydrofuran, 10 μL of the solution was injected into an apparatus equipped with columns manufactured by Tosoh Corporation (two TSKgelSuperHZM-H columns (6.0 mm inner diameter, 15 cm length) and a TSKguardcolumn SuperHZ-H column (4.6 mm inner diameter, 3.5 cm length)). Measurement was performed at a flow rate of 0.5 mL / min, with tetrahydrofuran as the eluent (BHT as a stabilizer) and a column temperature of 40°C. The weight-average molecular weight (Mw) was calculated on a standard polystyrene basis.

[0071] [Raw materials] The abbreviations for the raw materials used in this example are shown below. ·FM-0711: Reactive polydimethylsiloxane (R in formula (M1)) 1 : Methyl group, R 2 Q: n-butyl group, Q: n-propyl group, X: methacryloyloxy group, Mn: 1,000, manufactured by JNC Corporation, product name FM-0711) ·FM-0721: Reactive polydimethylsiloxane (R in formula (M1)) 1 : Methyl group, R 2 Q: n-butyl group, Q: n-propyl group, X: methacryloyloxy group, Mn: 5,000, manufactured by JNC Corporation, product name FM-0721) ·FM-0725: Reactive polydimethylsiloxane (R in formula (M1)) 1 : Methyl group, R 2 Q: n-butyl group, Q: n-propyl group, X: methacryloyloxy group, Mn: 10,000, manufactured by JNC Corporation, product name FM-0725) • LA:n-Lauryl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name: LA) • 4HBA: 4-Hydroxybutyl acrylate (manufactured by Mitsubishi Chemical Corporation, product name: 4HBA) nBA: n-butyl acrylate SLMA: A mixture of alkyl methacrylate with 12 carbon atoms in the alkyl group and alkyl methacrylate with 13 carbon atoms in the alkyl group (Mitsubishi Chemical Corporation's "Acryester SL"). • AMBN: 2,2'-Azobis(2-methylbutyronitrile)

[0072] [Manufacturing Example 1] In a reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet, 70 parts of toluene and 50 parts of FM-0711 were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The liquid temperature was raised to 85°C, and a mixture consisting of 30 parts of toluene, 25 parts of nBA, 25 parts of LA, 0.1 part of Luperox 575 as a polymerization initiator, and 0.3 parts of Nofmer MSD as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of toluene (40 parts) and Luperox 575 (0.5 parts) was added dropwise over 1 hour. The temperature was raised to 105°C and held for 1 hour, then toluene (10 parts) was added and the mixture was cooled to obtain a polymer solution containing 40% by mass of copolymer (C-1).

[0073] [Manufacturing Examples 2-5] A polymer solution containing 40% by mass of copolymers (C-2) to (C-5) was obtained by the same method as in Production Example 1, except that the monomer composition was changed as shown in Table 1.

[0074] [Manufacturing Example 6] (Synthesis of Co complexes (cobalt chain transfer agents)) In a synthesis apparatus equipped with a stirring device, 2.00 g (8.03 mmol) of cobalt(II) acetate tetrahydrate (Wako Pure Chemical Industries, Ltd., Wako Special Grade), 3.86 g (16.1 mmol) of diphenylglyoxime (Tokyo Chemical Industries, Ltd., EP Grade), and 100 mL of diethyl ether that had been deoxygenated beforehand by nitrogen bubbling were added under a nitrogen atmosphere, and the mixture was stirred at 25°C for 2 hours. Next, 20 mL of boron trifluoride diethyl ether complex (Tokyo Chemical Industries, Ltd., EP grade) was added, and the mixture was stirred for a further 6 hours. After filtering the resulting solution, the solid was washed with diethyl ether. Subsequently, it was dried at 20°C under a pressure of 100 MPa or less for 12 hours to obtain 5.02 g (7.93 mmol, yield 99% by mass) of the brownish solid Co complex.

[0075] [Manufacturing Example 7] In a reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet, 100 parts of SLMA, 0.001 parts of the Co complex obtained in Production Example 6 as a chain transfer agent, and 58 parts of ethyl acetate were charged, and oxygen was replaced by nitrogen bubbling for 1 hour. Next, 0.4 parts of AMBN as a polymerization initiator and 2 parts of ethyl acetate were added. Then, the ambient temperature was raised to 90°C using a water bath, and the reaction was carried out under reflux for 2 hours. Next, 0.2 parts of AMBN and 20 parts of ethyl acetate were added dropwise over 1 hour, and the mixture was then maintained under reflux for another 2 hours. The reaction mixture was then cooled to room temperature to obtain a solution containing the macromonomer (SLMA-MM). The non-volatile content was adjusted to 53% by mass by adding ethyl acetate to this solution. The number-average molecular weight of the macromonomer (SLMA-MM) was 5,000.

[0076] [Manufacturing Example 8] In a reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet, 26.7 parts of toluene and 94.34 parts of a solution containing 53% by mass of macromonomer (SLMA-MM) were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the solution was raised to 85°C, and a mixture consisting of 30 parts of toluene, 25 parts of nBA, 25 parts of LA, 0.1 part of Luperox 575 as a polymerization initiator, and 0.3 parts of Nofmer MSD as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of toluene (40 parts) and Luperox 575 (0.5 parts) was added dropwise over 1 hour. The temperature was raised to 105°C and held for 1 hour, then toluene (10 parts) was added and the mixture was cooled to obtain polymer solution (X-1) containing 40% by mass of copolymer (X-1).

[0077] Table 1 shows the monomer composition of each production example and the measurement results of the weight-average molecular weight of the obtained copolymer.

[0078] [Table 1]

[0079] [Kinematic viscosity] A lubricant composition containing 2% by mass of copolymer (C) and 98% by mass of silicone oil was prepared using the method described in the examples. The kinematic viscosity (KV40) of the composition at 40°C was measured using a fully automatic simple kinematic viscometer (Cannon, trade name: Simple-VIS) in accordance with the ASTM D7279 (D445) method.

[0080] [Storage stability when silicone oil is dissolved] Each example composition was left to stand at 25°C, and its condition was visually inspected and evaluated according to the following evaluation criteria. <Evaluation Criteria> A: No separation for more than 3 days B: Separate within 3 days C: Separation within 1 hour

[0081] [Friction test (Stribeck test)] A lubricant composition containing 2% by mass of copolymer (C) and 98% by mass of silicone oil was prepared using the method described in the examples, and the coefficient of friction at 40°C was measured using a UMT TriboLab testing machine (Brukbr). The measurement conditions were as follows, and the average value of the coefficient of friction at each rotational speed was measured when the rotational speed was increased from 1571 mm / s to 2 mm / s for 120 seconds each, and the values ​​of the coefficient of friction at rotational speeds of 52 mm / s and 2 mm / s were evaluated. Measurement conditions for the coefficient of friction: • Test method: Ball on disc (ball diameter: 10mm, ball and disc material: SUJ2). • Test mode: Rotation (average value over 120 seconds each at 1571 mm / s, 1047 mm / s, 524 mm / s, 209 mm / s, 157 mm / s, 105 mm / s, 52 mm / s, 2 mm / s). • Load: 5N.

[0082] [Example 1] 98 parts of dimethyl silicone oil (product name "KF-96-30CS", manufactured by Shin-Etsu Chemical Co., Ltd.) were used as the silicone oil. 5 parts of a polymer solution containing 40% by mass of polymer (C-1) obtained in Production Example 1 were added, and the volatile solvent was removed by vacuum distillation at 100°C for 3 hours under reduced pressure to obtain a lubricant composition containing 98 parts of silicone oil and 2 parts of polymer (C-1).

[0083] [Examples 2-5, Comparative Example 1] A lubricant composition was obtained in the same manner as in Example 1, except that the polymer solution used was changed as shown in Table 2.

[0084] [Comparative Example 2] 100 units of dimethyl silicone oil (product name "KF-96-30CS", manufactured by Shin-Etsu Chemical Co., Ltd.) were used as a comparison sample.

[0085] The evaluation results for each case are shown in Table 2.

[0086] [Table 2]

[0087] As shown in Table 2, the lubricant compositions of Examples 1 to 5, which contain copolymer (C) and silicone oil, exhibited excellent storage stability when copolymer (C) was dissolved in silicone oil, and also showed a higher friction reduction effect compared to Comparative Example 2. In Comparative Example 1, the lubricant composition using copolymer (X-1) could not undergo a friction test because copolymer (X-1) did not dissolve sufficiently in silicone oil.

Claims

1. A lubricant composition comprising a polymer block (A) having the structure of the following formula (1), a copolymer (C) having a (meth)acrylic polymer block (B), and a silicone oil. 【Chemistry 1】 (However, in equation (1), R １ These are alkyl groups, alkenyl groups, aryl groups, alkylaryl groups, arylalkyl groups, alkyl groups containing a fluorine atom, alkenyl groups containing a fluorine atom, aryl groups containing a fluorine atom, alkylaryl groups containing a fluorine atom, or arylalkyl groups containing a fluorine atom. １ These may be the same group or different groups.

2. The lubricant composition according to claim 1, wherein the (meth)acrylic polymer block (B) comprises a constituent unit derived from alkyl (meth)acrylate having an alkyl group having 1 to 30 carbon atoms.

3. The lubricant composition according to claim 1, wherein the number average molecular weight of the polymer block (A) is 500 to 100,000.

4. The lubricant composition according to claim 1, wherein the number average molecular weight of the polymer block (A) is 2,000 to 50,000.

5. The lubricant composition according to claim 1, wherein the content of the polymer block (A) in the copolymer (C) is 5 to 90% by mass relative to the total mass of the copolymer (C).

6. The lubricant composition according to claim 1, wherein the weight-average molecular weight of the copolymer (C) is 10,000 to 1,000,000.

7. The lubricant composition according to claim 1, wherein the kinematic viscosity at 40°C is 10 to 500 cSt when it contains 2% by mass of the copolymer (C).

8. The lubricant composition according to claim 1, wherein the copolymer (C) is a friction reducing agent.

9. A grease comprising the lubricant composition according to any one of claims 1 to 8 and a thickener.

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