Lubricating oil additive, polymer, viscosity index improver, lubricating oil, and method for producing lubricating oil additive

Abstract

To provide a lubricating oil additive, a polymer, a viscosity index improver, a lubricating oil, and a method for producing the lubricating oil additive, which exhibit excellent viscosity index improving capability and oil solubility when added to an oil.SOLUTION: A lubricating oil additive comprises a polymer and a solvent, where the polymer comprises a structural unit (A) derived from a compound represented by the general formula (1) in the figure, and a structural unit (B) derived from a (meth)acryloyl group-containing compound, the (meth)acryloyl group-containing compound having two or more (meth)acryloyl groups, and the content of the structural unit (B) is 0.1 to 20 mass% relative to the total mass of all structural units constituting the polymer. (In the general formula (1), R1 represents a group represented by CnH2n+m, n is an integer of 1-30, m is one of -3, -1 and 1, and 2n+m is an integer of 3 or more.)SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a lubricating oil additive, a polymer, a viscosity index improver, a lubricating oil, and a method for producing a lubricating oil additive.

Background Art

[0002] Conventionally, lubricating oils have been used in internal combustion engines, automatic transmissions, and other mechanical devices to smooth their operation. In recent years, from the perspective of global environmental protection, the fuel-saving performance required of lubricating oils has been increasing, and further improvement of the viscosity index, which is one of the indicators, is required.

[0003] A copolymer composed of a structural unit derived from a conjugated diene and a structural unit derived from an aromatic vinyl compound disclosed in Patent Document 1 is used as a viscosity index improver for lubricating oils.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the viscosity index improver disclosed in Patent Document 1 has a problem that when the content of the structural unit derived from the aromatic vinyl compound is large, the solubility in oil decreases.

[0006] An object of the present invention is to provide a lubricating oil additive, a polymer, a viscosity index improver, a lubricating oil, and a method for producing a lubricating oil additive that have excellent viscosity index improving ability and solubility in oil when added to oil.

Means for Solving the Problems

[0007] The present invention has the following aspects. [1] including a polymer and a solvent, The polymer contains a structural unit (A) derived from a compound represented by the following general formula (1) and a structural unit (B) derived from a (meth)acryloyl group-containing compound, The (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, A lubricating oil additive in which the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer.

[0008]

Chemical formula

[0009] In the general formula (1), R 1 is a group represented by C n H 2n+m n is an integer from 1 to 30, m is any one of -3, -1, and 1, and 2n + m is an integer of 3 or more.

[0010] [2] The polymer further contains a structural unit (C) (excluding the structural unit (B)) derived from a (meth)acryloyl group-containing compound having at least one functional group selected from an alkyl group, a hydroxy group, a silyloxy group, a vinyl group, an ether group, an amino group, a carboxy group, a fluorine atom, and a phosphate group. The lubricating oil additive according to [1] above. [3] In the general formula (1), n is an integer from 2 to 11, m is -3 or -1, and 2n + m is an integer from 3 to 19. The lubricating oil additive according to [1] or [2] above. [4] In the general formula (1), n is an integer from 6 to 11, and m is -3 or -1. The lubricating oil additive according to [1] or [2] above. [5] In the general formula (1), R 1 is a group represented by C6H 11 The lubricating oil additive according to any one of [1] to [4] above. [6] The (meth)acryloyl group-containing compound includes a compound represented by the following general formula (2). The lubricating oil additive according to any one of [1] to [5] above. CH2=CR 2-COO-(R 3 O) n -COCR 4 =CH2···(2) (In general formula (2), R 2 and R 4 are each independently a hydrogen atom or a methyl group, R 3 is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

[0011] [7] A lubricant additive comprising a polymer and a solvent, wherein the polymer contains a structural unit (A1) derived from myrcene and a structural unit (B) derived from a (meth)acryloyl group-containing compound, the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, and the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer.) [8] The lubricant additive according to [7], wherein the (meth)acryloyl group-containing compound contains a compound represented by the following general formula (2). CH2=CR 2 -COO-(R 3 O) n -COCR 4 =CH2···(2) (In general formula (2), R 2 and R 4 are each independently a hydrogen atom or a methyl group, R 3 is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

[0012] [9] A polymer containing a structural unit (A) derived from a compound represented by the following general formula (1) and a structural unit (B) derived from a (meth)acryloyl group-containing compound, wherein the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units, and the weight average molecular weight is 10,000 to 500,000.)

[0013] [Chemical]

[0014] In general formula (1), R 1 is a group represented by C n H 2n+m and n is an integer from 1 to 30, m is any one of -3, -1 and 1, and 2n + m is an integer of 3 or more.

[0015]

[10] In the general formula (1), n is an integer from 2 to 11, m is -3 or -1, and 2n + m is an integer from 3 to 19, the polymer of [9] above.

[11] In the general formula (1), n is an integer from 6 to 11, m is -3 or -1, the polymer of [9] above.

[12] In the general formula (1), R 1 is a group represented by C6H 11 and is the polymer of any one of [9] to

[11] above.

[13] The (meth)acryloyl group-containing compound contains a compound represented by the following general formula (2), and is the polymer of any one of [9] to

[12] above. CH2=CR 2 -COO-(R 3 O) n -COCR 4 =CH2 ··· (2) (In general formula (2), R 2 and R 4 are each independently a hydrogen atom or a methyl group, and R 3 is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

[14] A lubricating oil additive containing the polymer of any one of [9] to

[13] above and a solvent.

[0016]

[15] It contains a structural unit (A1) derived from myrcene and a structural unit (B) derived from a (meth)acryloyl group-containing compound, the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, The content of the constitutional unit (B) is 0.1 to 20% by mass based on the total mass of all constitutional units, a polymer having a weight average molecular weight of 10,000 to 500,000.

[16] The polymer of

[15] above, wherein the (meth)acryloyl group-containing compound includes a compound represented by the following general formula (2). CH2=CR 2 -COO-(R 3 O) n -COCR 4 =CH2···(2) (In the general formula (2), R 2 and R 4 are each independently a hydrogen atom or a methyl group, R 3 is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

[17] A lubricant additive comprising the polymer of

[15] or

[16] above and a solvent.

[0017]

[18] The lubricant additive according to any one of [1] to [8],

[14] , and

[17] above, wherein the solvent includes at least one of mineral oil and synthetic chemical oil.

[19] A viscosity index improver comprising the lubricant additive according to any one of [1] to [8],

[14] ,

[17] , and

[18] above.

[20] A lubricating oil comprising the lubricant additive according to any one of [1] to [8],

[14] ,

[17] , and

[18] above.

[0018]

[21] A method for producing a lubricant additive, comprising a step of producing a polymer in a solvent, wherein the polymer includes a constitutional unit (A) derived from a compound represented by the following general formula (1) and a constitutional unit (B) derived from a (meth)acryloyl group-containing compound, the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, and the content of the constitutional unit (B) is 0.1 to 20% by mass based on the total mass of all constitutional units constituting the polymer.

[0019] [Chemical formula]

[0020] In general formula (1), R 1 is a group represented by C n H 2n+m and n is an integer from 1 to 30, m is any one of -3, -1, and 1, and 2n + m is an integer of 3 or more.

[0021]

[22] A method for producing a lubricant additive, comprising a step of producing a polymer in a solvent, wherein the polymer contains a structural unit (A1) derived from myrcene and a structural unit (B) derived from a (meth)acryloyl group-containing compound, wherein the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, and the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer.

[23] A method for producing a lubricant additive, comprising a step of producing a polymer in a solvent, wherein the polymer contains a structural unit (A) derived from a compound represented by the following general formula (1) and a structural unit (B) derived from a (meth)acryloyl group-containing compound, wherein the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, and the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer, and the weight average molecular weight of the polymer is 10,000 to 500,000.

[0022] [Chemical formula]

[0023] In general formula (1), R 1 is a group represented by C n H 2n+m and n is an integer from 1 to 30, m is any one of -3, -1, and 1, and 2n + m is an integer of 3 or more.

[0024]

[24] The method for producing a lubricant additive includes a step of producing a polymer in a solvent, wherein the polymer includes a structural unit (A1) derived from miltirone and a structural unit (B) derived from a (meth)acryloyl group-containing compound, the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer, and the weight average molecular weight of the polymer is 10,000 to 500,000.

[25] The method for producing a lubricant additive according to any one of

[21] to

[24] , wherein the solvent includes at least one of mineral oil and synthetic chemical oil.

[26] In the general formula (1), n is an integer of 2 to 11, m is -3 or -1, and 2n + m is an integer of 3 to 19. The method for producing a lubricant additive according to

[21] or

[23] .

[27] In the general formula (1), n is an integer of 6 to 11, and m is -3 or -1. The method for producing a lubricant additive according to

[21] or

[23] .

[28] In the general formula (1), R 1 is a group represented by C6H 11 . The method for producing a lubricant additive according to any one of

[21] ,

[23] ,

[26] and

[27] .

[29] The method for producing a lubricant additive according to any one of

[21] to

[28] , wherein the (meth)acryloyl group-containing compound includes a compound represented by the following general formula (2). CH2=CR 2 -COO-(R 3 O) n -COCR 4 =CH2 ··· (2) (In the general formula (2), R 2 and R 4 are each independently a hydrogen atom or a methyl group, R 3 is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

[30] The polymer further contains a structural unit (C) (excluding the structural unit (B)) derived from a (meth)acryloyl group-containing compound having at least one functional group selected from an alkyl group, a hydroxy group, a silyloxy group, a vinyl group, an ether group, an amino group, a carboxy group, a fluorine atom, and a phosphate group, and is a method for producing any one of the lubricant additives according to

[21] to

[29] above.

[31] The polymer further contains a structural unit (C) (excluding the structural unit (B)) derived from a (meth)acryloyl group-containing compound having at least one functional group selected from an alkyl group, a hydroxy group, a silyloxy group, a vinyl group, an ether group, an amino group, a carboxy group, a fluorine atom, and a phosphate group, and is the lubricant additive according to [7] or [8] above.

[32] The polymer further contains a structural unit (C) (excluding the structural unit (B)) derived from a (meth)acryloyl group-containing compound having at least one functional group selected from an alkyl group, a hydroxy group, a silyloxy group, a vinyl group, an ether group, an amino group, a carboxy group, a fluorine atom, and a phosphate group, and is any one of the polymers according to [9] to

[13] ,

[15] , and

[16] above. [Effect of the Invention]

[0025] According to the present invention, when added to oil, it is possible to provide a lubricant additive, a polymer, a viscosity index improver, a lubricating oil, and a method for producing a lubricant additive, which have excellent viscosity index improvement ability and solubility in oil. [Embodiments for Carrying Out the Invention]

[0026] Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited to the following embodiments and can be variously modified and implemented within the scope of the gist thereof. In the present specification and the 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. In the present invention, the "structural unit" means a unit that constitutes 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. Also, the "(meth)acryloyl group" is a general term for the "acryloyl group" and the "methacryloyl group", and the same applies to "(meth)acrylate" and "(meth)acrylic". In this specification, the "weight average molecular weight" and the "number average molecular weight" respectively mean the weight average molecular weight or the number average molecular weight in terms of standard polystyrene measured by the gel permeation chromatography (GPC) method.

[0027] [Polymer] "First Aspect" The polymer of the first aspect of the present invention (hereinafter, also referred to as "polymer (X1)") contains the following structural unit (A) and structural unit (B). The polymer (X1) may further contain, as necessary, a structural unit other than the structural unit (A) and the structural unit (B) (hereinafter, also referred to as "structural unit (C)") within a range not impairing the effects of the present invention.

[0028] <Structural Unit (A)> The structural unit (A) is a structural unit derived from a compound represented by the following general formula (1) (hereinafter, also referred to as "compound (A)"). The structural unit (A) is preferably derived from a monomer obtained from a plant. That is, the compound (A) is preferably a monomer derived from a plant. Whether it is a monomer derived from a plant can be confirmed by measuring the radioactive carbon concentration.

[0029] [Chemical Formula]

[0030] In general formula (1), R 1 is C n H2n+m a group represented by, where n is an integer from 1 to 30, m is either -3, -1 or 1, and 2n + m is an integer of 3 or more.

[0031] n is an integer from 1 to 30, preferably an integer from 2 to 11, more preferably an integer from 6 to 11, still more preferably an integer from 6 to 10, particularly preferably an integer from 6 to 8, and most preferably 6. When n is below the above upper limit, it exhibits excellent solubility in oil. m is either -3, -1 or 1, preferably -3 or -1, and more preferably -1. 2n + m is an integer of 3 or more, preferably an integer from 3 to 61, more preferably an integer from 3 to 21, still more preferably an integer from 3 to 19, particularly preferably 11 to 19, and most preferably 11.

[0032] In particular, n is preferably an integer from 2 to 11 and m is -3 or -1. In this case, 2n + m is preferably an integer from 3 to 21, and more preferably an integer from 3 to 19. Among them, in particular, n is preferably an integer from 6 to 11 and m is -3 or -1, more preferably n is an integer from 6 to 10 and m is -3 or -1, still more preferably n is an integer from 6 to 8 and m is -1, and particularly preferably n is 6 and m is -1. R 1 Examples of include a group represented by C6H 11 a group represented by C6H 13 a group represented by C 11 H 19 a group represented by C 11 H 21 a group represented by C 11 H 23 a group represented by C6H 11 a group represented by C 11 H 19 a group represented by C6H 11 a group represented by are preferred, a group represented by C6H R 1 When is a group represented by C6H 11 Examples of compound (A) include myrcene. R1 is C 11 H 19 When it is a group represented by, β-farnesene can be mentioned as the compound (A).

[0033] As the structural unit (A), a structural unit derived from at least one of myrcene and β-farnesene is preferable, and a structural unit derived from myrcene (hereinafter, also referred to as "structural unit (A1)") is more preferable from the viewpoint of raw material price. Both myrcene and β-farnesene are available as plant-derived monomers, which is preferable from the viewpoint of constructing a carbon recycling society. The polymer (X1) may contain only one type of structural unit (A), or may contain two or more types of structural units (A).

[0034] The content of the structural unit (A) is preferably 80 to 99.9% by mass, more preferably 85 to 99.5% by mass, still more preferably 90 to 99.5% by mass, particularly preferably 95 to 99.5% by mass, and most preferably 95 to 99% by mass with respect to the total mass of all the structural units constituting the polymer (X1). When the content of the structural unit (A) is at least the above lower limit value, the solubility in oil, that is, the solubility in oil is further improved. In addition, the polymer (X1) is less likely to gel. When the content of the structural unit (A) is at most the above upper limit value, the ability to improve the viscosity index is further enhanced. The content of the structural unit (A) can be determined by calculation from the charged amount of the compound (A), which is a monomer for introducing the structural unit (A), as the raw material monomer of the polymer (X1).

[0035] <Structural unit (B)> The structural unit (B) is a structural unit derived from a (meth)acryloyl group-containing compound (hereinafter, also referred to as "compound (B)"). When the polymer (X1) contains the structural unit (B), the ability to improve the viscosity index is enhanced.

[0036] The compound (B) has two or more (meth)acryloyl groups in the molecule. Examples of the compound (B) include bifunctional monomers having two (meth)acryloyl groups, trifunctional monomers having three (meth)acryloyl groups, and tetrafunctional or higher monomers having four or more (meth)acryloyl groups.

[0037] Examples of the bifunctional monomer include compounds represented by the following general formula (2). CH2=CR 2 -COO-(R 3 O) n -COCR 4 =CH2···(2) (In the general formula (2), R 2 and R 4 are each independently a hydrogen atom or a methyl group, R 3 is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

[0038] R 3 is an alkylene group having 1 to 10 carbon atoms, preferably an alkylene group having 1 to 8 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, and even more preferably an alkylene group having 2 to 4 carbon atoms. n is an integer of 1 or more, preferably 1 to 30, more preferably 1 to 20, even more preferably 1 to 16, particularly preferably 1 to 14, and most preferably 1 to 12. When n is 2 or more, the plurality of R 3 O may be the same or different.

[0039] Examples of the compound represented by the general formula (2) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6 - hexanediol di(meth)acrylate, 1,5 - pentanediol di(meth)acrylate, 1,3 - butanediol di(meth)acrylate, polybutylene glycol di(meth)acrylate, and the like.

[0040] Examples of the trifunctional monomer include pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and the like. Examples of the monomer having four or more functional groups include dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane tetraacrylate, tetramethylolmethane tetra(meth)acrylate, and the like.

[0041] As the compound (B), the compound represented by the general formula (2) is preferable, and among them, 1,3 - butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate are more preferable, and 1,3 - butanediol di(meth)acrylate is even more preferable. That is, as the structural unit (B), the structural unit derived from the compound represented by the general formula (2) is preferable. The polymer (X1) may contain only one type of the structural unit (B) or may contain two or more types of the structural unit (B).

[0042] The content of the structural unit (B) is 0.1 to 20% by mass, preferably 0.5 to 15% by mass, more preferably 0.5 to 10% by mass, still more preferably 0.5 to 5% by mass, and particularly preferably 1 to 5% by mass with respect to the total mass of all the structural units constituting the polymer (X1). If the content of the structural unit (B) is at least the above lower limit, the ability to improve the viscosity index is enhanced. If the content of the structural unit (B) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is improved. In addition, the polymer (X1) is less likely to gel. Incidentally, the content of the structural unit (B) can be determined by calculation from the charged amount of the compound (B), which is a monomer for introducing the structural unit (B), as a raw material monomer of the polymer (X1).

[0043] <Structural unit (C)> The structural unit (C) is a structural unit other than the structural unit (A) and the structural unit (B). That is, the structural unit (C) is a structural unit derived from a compound other than the compound (A) and the compound (B) (hereinafter also referred to as "compound (C)").

[0044] The compound (C) is not particularly limited as long as it is copolymerizable with at least one of the compound (A) and the compound (B). Examples thereof include a compound having one (meth)acryloyl group in the molecule (hereinafter also referred to as "(meth)acryloyl group-containing compound (C1)"). (Meth)acryloyl group-containing compounds (C1) include, for example, linear or branched alkyl group-containing (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, i-pentyl (meth)acrylate, 2-methylbutyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, etc.; alicyclic (meth)acrylates such as cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, etc.; hydroxy group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1,2-dihydroxyethyl (meth)acrylate, 1,2-dihydroxypropyl (meth)acrylate, 1,2-dihydroxybutyl (meth)acrylate, 1,2-dihydroxy-5-ethylhexyl (meth)acrylate, 1,1-dihydroxyethyl (meth)acrylate, 1,1-dihydroxypropyl (meth)acrylate, 1,1-dihydroxybutyl (meth)acrylate, 1,2,3-trihydroxypropyl (meth)acrylate, 1,2,3-trihydroxybutyl (meth)acrylate, 1,1,2-trihydroxypropyl (meth)acrylate, 1,1,2-trihydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, etc.; silyloxy group-containing (meth)acrylates such as trimethylsilyloxyethyl (meth)acrylate, etc.; vinyl group-containing (meth)acrylates such as allyl (meth)acrylate, etc.;Ether group-containing acrylic acid esters such as 2-methoxyethyl (meth)acrylate, 1,3-butylene glycol methyl ether (meth)acrylate, butoxyethyl (meth)acrylate, methoxy triethylene glycol (meth)acrylate, methoxy dipropylene glycol (meth)acrylate, methoxy tripropylene glycol (meth)acrylate, methoxy polypropylene glycol (meth)acrylate, ethoxy diethylene glycol (meth)acrylate, ethyl carbitol (meth)acrylate, 2-ethylhexyl carbitol (meth)acrylate; Epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate, glycidyl α-ethylacrylate, 3,4-epoxybutyl (meth)acrylate; Amino group-containing (meth)acrylates such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate; Amide group-containing (meth)acrylates such as (meth)acrylamide, N-t-butyl (meth)acrylamide, N-methylol (meth)acrylamide, N-isopropylacrylamide, hydroxyethylacrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, diacetoneacrylamide; Carboxy group-containing (meth)acrylates such as (meth)acrylic acid, succinic acid mono(2-(meth)acryloyloxyethyl), ω-carboxy-polycaprolactone mono(meth)acrylate;Fluorine atom-containing (meth)acrylates such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3,3-pentafluorophenyl (meth)acrylate, 2-(perfluorobutyl)ethyl (meth)acrylate, 3-(perfluorobutyl)-2-hydroxypropyl (meth)acrylate, 2-(perfluorohexyl)ethyl (meth)acrylate, 3-perfluorohexyl-2-hydroxypropyl (meth)acrylate, 3-(perfluoro-3-methylbutyl)-2-hydroxypropyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)methacrylate, 1H,1H,2H,2H-tridecafluorooctyl (meth)acrylate, 1H-1-(trifluoromethyl)trifluoroethyl (meth)acrylate, 1H,1H,3H-hexafluorobutyl (meth)acrylate, 1,2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl (meth)acrylate; Phosphoric acid group-containing (meth)acrylates such as 2-(meth)acryloyloxyethyl acid phosphate and 2-(meth)acryloyloxyethyl acid phosphate monoethanolamine salt, diphenyl((meth)acryloyloxyethyl)phosphate, (meth)acryloyloxypropyl acid phosphate, 3-chloro-2-acid phosphooxypropyl (meth)acrylate, acid phosphooxypolyoxyethylene glycol mono(meth)acrylate, acid phosphooxypolyoxypropylene glycol (meth)acrylate, etc. are mentioned.;

[0045] Examples of compound (C) include, in addition to the compounds described above, carboxy group-containing monomers such as itaconic acid, crotonic acid, maleic acid, and fumaric acid; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; aromatic vinyl monomers such as styrene, α-methylstyrene, and α-ethylstyrene; vinyl ether monomers such as vinyl methyl ether and vinyl ethyl ether; vinyl carboxylate monomers such as vinyl acetate and vinyl butyrate; olefin monomers such as ethylene, propylene, and isobutylene; vinyl halide monomers such as vinyl chloride and vinylidene chloride; maleimide monomers such as maleimide, N-phenylmaleimide, N-cyclohexylmaleimide, and N-methylmaleimide, and the like.

[0046] As compound (C), a (meth)acryloyl group-containing compound (C1) is preferred. Among them, a (meth)acryloyl group-containing compound (C1) having at least one functional group selected from an alkyl group, a hydroxy group, a silyloxy group, a vinyl group, an ether group, an amino group, a carboxy group, a fluorine atom, and a phosphate group is more preferred, and a hydroxy-containing (meth)acrylate and a carboxy group-containing (meth)acrylate are even more preferred, and 4-hydroxybutyl (meth)acrylate, polypropylene glycol mono (meth)acrylate, and (meth)acrylic acid are particularly preferred. That is, as the constitutional unit (C), it is preferably a constitutional unit derived from a (meth)acrylate having one (meth)acryloyl group and a hydroxy group in the molecule. The polymer (X1) may contain only one type of constitutional unit (C) or may contain two or more types of constitutional units (C).

[0047] The content of the constitutional unit (C) is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 8% by mass or less based on the total mass of all the constitutional units constituting the polymer (X1). When the content of the constitutional unit (C) is below the above upper limit value, the solubility in oil, that is, the solubility in oil is further improved. The content of the constitutional unit (C) can be determined by calculation from the charged amount of the compound (C), which is a monomer for introducing the constitutional unit (C), as a raw material monomer of the polymer (X1).

[0048] <Physical properties> The weight average molecular weight of the polymer (X1) is from 10,000 to 500,000, preferably from 30,000 to 400,000, and more preferably from 40,000 to 300,000. If the weight average molecular weight of the polymer (X1) is at least the above lower limit, the ability to improve the viscosity index is enhanced. If the weight average molecular weight of the polymer (X1) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is improved.

[0049] The number average molecular weight of the polymer (X1) is preferably from 5,000 to 50,000, more preferably from 8,000 to 40,000, and even more preferably from 10,000 to 30,000. If the weight average molecular weight of the polymer (X1) is at least the above lower limit, the ability to improve the viscosity index is further enhanced. If the weight average molecular weight of the polymer (X1) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is further improved.

[0050] <Production method> The polymer (X1) can be obtained by polymerizing the compound (A), the compound (B), and, if necessary, the compound (C). The polymerization method is not particularly limited, and known methods can be adopted. Examples include solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. Among these, from the viewpoint of compatibility with lubricant additives, the solution polymerization method is preferred. That is, it is preferable to produce the polymer (X1) in a solvent. The polymer (X1) obtained by the solution polymerization method is obtained in the state of a polymer solution dissolved in a solvent. Hereinafter, an example of a method for producing the polymer (X1) by the solution polymerization method will be described in detail.

[0051] The polymer (X1) can be produced by polymerizing a monomer mixture (M1) containing the compound (A) and the compound (B) in a solvent by a known solution polymerization method. The monomer mixture (M1) may contain the compound (C) if necessary.

[0052] The content of compound (A) is preferably 80 to 99.9% by mass, more preferably 85 to 99.5% by mass, still more preferably 90 to 99.5% by mass, particularly preferably 95 to 99.5% by mass, and most preferably 95 to 99% by mass based on the total mass of the monomer mixture (M1). The content of compound (B) is 0.1 to 20% by mass, preferably 0.5 to 15% by mass, more preferably 0.5 to 10% by mass, still more preferably 0.5 to 5% by mass, and particularly preferably 1 to 5% by mass based on the total mass of the monomer mixture (M1). The content of compound (C) is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less based on the total mass of the monomer mixture (M1).

[0053] As the solvent, known polymerization solvents can be used. However, from the viewpoint of compatibility with lubricating oil additives, it is preferable to use base oils such as paraffinic oils, naphthenic oils, and aromatic oils (base oils). When using a base oil as the solvent in the production of polymer (X1), the polymer (X1) produced in the base oil and the base oil can be used as lubricating oil additives. Examples of base oils include mineral base oils refined from crude oil (hereinafter also simply referred to as "mineral oils") and synthetic oils chemically synthesized (hereinafter also referred to as "synthetic chemical oils"). Commercially available products can be used as the base oil. For example, API Group III base oils such as the product named "YUBASE3" manufactured by SK Lubricants Co., Ltd., base oils such as API Group III plus like the product named "YUBASE4" manufactured by SK Lubricants Co., Ltd., and polyalphaolefins such as the product named "DURASYN170" manufactured by INEOS Oligomers Co., Ltd. Among these, paraffinic oils such as YUBASE4 and DURASYN170 are preferable from the viewpoint of improving the viscosity index. The solvent may be used alone or in combination of two or more.

[0054] For the polymerization of the monomer mixture (M1), it is preferable to use a radical polymerization initiator. Examples of the radical polymerization initiator include organic peroxides such as t-butyl peroxypivalate, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, cyclohexanone peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate; azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile). Among these, organic peroxides are preferred, and among them, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate is particularly preferred. The radical polymerization initiator may be used alone or in combination of two or more.

[0055] The polymerization temperature is preferably 40 to 150 °C, more preferably 80 to 130 °C. The polymerization time is preferably 1 to 24 hours, more preferably 5 to 15 hours.

[0056] <Use> The polymer (X1) is suitable as an additive to be added to various lubricating oils such as engine oil, gear oil, hydraulic oil, drive system lubricating oil, and automatic transmission oil used in mobility such as industrial machinery, robots, and automobiles, that is, as a lubricating oil additive.

[0057] "Second Aspect" The polymer of the second aspect of the present invention (hereinafter also referred to as "polymer (X2)") contains the following structural unit (A1) and structural unit (B). The polymer (X2) may further contain a constitutional unit (C), in addition to the constitutional unit (A1) and the constitutional unit (B), as long as the effects of the present invention are not impaired.

[0058] <Constitutional unit (A1)> The constitutional unit (A1) is a constitutional unit derived from myrcene. Myrcene is available as a plant-derived monomer and is preferable from the viewpoint of constructing a carbon recycling society. The fact that it is a plant-derived monomer can be confirmed by measuring the radiocarbon concentration.

[0059] The content of the constitutional unit (A1) is preferably 80 to 99.9% by mass, more preferably 85 to 99.5% by mass, still more preferably 90 to 99.5% by mass, particularly preferably 95 to 99.5% by mass, and most preferably 95 to 99% by mass, based on the total mass of all the constitutional units constituting the polymer (X2). When the content of the constitutional unit (A1) is at least the above lower limit, the solubility in oil, that is, the ability to dissolve in oil, is further improved. In addition, the polymer (X2) is less likely to gel. When the content of the constitutional unit (A1) is at most the above upper limit, the ability to improve the viscosity index is further enhanced. The content of the constitutional unit (A1) can be determined by calculation from the charged amount of myrcene, which is a monomer for introducing the constitutional unit (A1), as the raw material monomer of the polymer (X2).

[0060] <Constitutional unit (B)> The constitutional unit (B) is a constitutional unit derived from the compound (B). When the polymer (X2) contains the constitutional unit (B), the ability to improve the viscosity index is enhanced. Examples of the compound (B) include the compounds (B) exemplified above in the description of the polymer (X1) of the first aspect. The polymer (X2) may contain only one type of constitutional unit (B) or may contain two or more types of constitutional units (B).

[0061] The content of the structural unit (B) is 0.1 to 20% by mass, preferably 0.5 to 15% by mass, more preferably 0.5 to 10% by mass, still more preferably 0.5 to 5% by mass, and particularly preferably 1 to 5% by mass, based on the total mass of all the structural units constituting the polymer (X2). If the content of the structural unit (B) is at least the above lower limit, the ability to improve the viscosity index is enhanced. If the content of the structural unit (B) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is improved. In addition, the polymer (X2) is less likely to gel. Incidentally, the content of the structural unit (B) can be determined by calculation from the charged amount of the compound (B), which is a monomer for introducing the structural unit (B), as a raw material monomer of the polymer (X2).

[0062] <Structural unit (C)> The structural unit (C) is a structural unit other than the structural unit (A1) and the structural unit (B). That is, the structural unit (C) is a structural unit derived from a compound other than myrcene and the compound (B). Examples of the compound other than myrcene and the compound (B) include the compound (C) exemplified above in the description of the polymer (X1) of the first aspect. The polymer (X2) may contain only one type of the structural unit (C) or may contain two or more types of the structural unit (C).

[0063] The content of the structural unit (C) is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less, based on the total mass of all the structural units constituting the polymer (X2). If the content of the structural unit (C) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is further improved. Incidentally, the content of the structural unit (C) can be determined by calculation from the charged amount of the compound (C), which is a monomer for introducing the structural unit (C), as a raw material monomer of the polymer (X2).

[0064] <Physical properties> The weight-average molecular weight of the polymer (X2) is from 10,000 to 500,000, preferably from 30,000 to 400,000, and more preferably from 40,000 to 300,000. If the weight-average molecular weight of the polymer (X2) is at least the above lower limit, the ability to improve the viscosity index is enhanced. If the weight-average molecular weight of the polymer (X2) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is improved.

[0065] The number-average molecular weight of the polymer (X2) is preferably from 5,000 to 50,000, more preferably from 8,000 to 40,000, and even more preferably from 10,000 to 30,000. If the weight-average molecular weight of the polymer (X2) is at least the above lower limit, the ability to improve the viscosity index is further enhanced. If the weight-average molecular weight of the polymer (X2) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is further improved.

[0066] <Production method> The polymer (X2) is obtained by polymerizing myrcene, compound (B), and optionally compound (C). The polymerization method is not particularly limited, but it is preferably produced by the same method as the polymer (X1). That is, the polymer (X2) is preferably produced by polymerizing a monomer mixture (M2) containing myrcene and compound (B) in a solvent by a known solution polymerization method. The monomer mixture (M2) may contain compound (C) as required.

[0067] The content of myrcene is preferably 80 to 99.9% by mass, more preferably 85 to 99.5% by mass, even more preferably 90 to 99.5% by mass, particularly preferably 95 to 99.5% by mass, and most preferably 95 to 99% by mass based on the total mass of the monomer mixture (M2). The content of compound (B) is 0.1 to 20% by mass, preferably 0.5 to 15% by mass, more preferably 0.5 to 10% by mass, even more preferably 0.5 to 5% by mass, and particularly preferably 1 to 5% by mass based on the total mass of the monomer mixture (M2). The content of the compound (C) is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less with respect to the total mass of the monomer mixture (M2).

[0068] When the polymer (X2) is produced by a solution polymerization method, examples of the solvent and the radical polymerization initiator used in the polymerization include the solvents and radical polymerization initiators exemplified above in the description of the polymer (X1) of the first aspect. Also, the polymerization temperature and the polymerization time are the same as those in the case of producing the polymer (X1).

[0069] [Use] The polymer (X2) is suitable as an additive to be added to various lubricating oils such as engine oil, gear oil, hydraulic oil, drive system lubricating oil, and automatic transmission oil used in mobility such as industrial machines, robots, and automobiles, that is, as a lubricating oil additive.

[0070] [Lubricating oil additive] "Third aspect" The lubricating oil additive (hereinafter, also referred to as "lubricating oil additive (Y1)") of the third aspect of the present invention contains a polymer and a solvent.

[0071] [Polymer] The polymer (hereinafter, also referred to as "polymer (x1)") contained in the lubricating oil additive (Y1) contains a structural unit (A) derived from the compound (A) and a structural unit (B) derived from the compound (B). The polymer (x1) may further contain a structural unit (C) derived from the compound (C) in addition to the structural unit (A) and the structural unit (B), if necessary, as long as the effects of the present invention are not impaired. Examples of the compound (A), the compound (B), and the compound (C) include the compound (A), the compound (B), and the compound (C) exemplified above in the description of the polymer (X1) of the first aspect.

[0072] The polymer (x1) may contain only one type of structural unit (A) or may contain two or more types of structural units (A). The content of the structural unit (A) is preferably 80 to 99.9% by mass, more preferably 85 to 99.5% by mass, still more preferably 90 to 99.5% by mass, particularly preferably 95 to 99.5% by mass, and most preferably 95 to 99% by mass, based on the total mass of all the structural units constituting the polymer (x1). If the content of the structural unit (A) is at least the above lower limit value, the solubility in oil, i.e., the ability to dissolve in oil, is further improved. In addition, the polymer (x1) is less likely to gel. If the content of the structural unit (A) is at most the above upper limit value, the ability to improve the viscosity index is further enhanced. Incidentally, the content of the structural unit (A) can be determined by calculation from the charged amount of the compound (A), which is a monomer for introducing the structural unit (A), as the raw material monomer of the polymer (x1).

[0073] The polymer (x1) may contain only one kind of structural unit (B) or may contain two or more kinds of structural units (B). The content of the structural unit (B) is 0.1 to 20% by mass, preferably 0.5 to 15% by mass, more preferably 0.5 to 10% by mass, still more preferably 0.5 to 5% by mass, and particularly preferably 1 to 5% by mass, based on the total mass of all the structural units constituting the polymer (x1). If the content of the structural unit (B) is at least the above lower limit value, the ability to improve the viscosity index is enhanced. If the content of the structural unit (B) is at most the above upper limit value, the solubility in oil, i.e., the ability to dissolve in oil, is improved. In addition, the polymer (x1) is less likely to gel. Incidentally, the content of the structural unit (B) can be determined by calculation from the charged amount of the compound (B), which is a monomer for introducing the structural unit (B), as the raw material monomer of the polymer (x1).

[0074] The polymer (x1) may contain only one kind of structural unit (C) or may contain two or more kinds of structural units (C). The content of the structural unit (C) is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less, based on the total mass of all the structural units constituting the polymer (x1). If the content of the structural unit (C) is below the above upper limit value, the solubility in oil, i.e., the solubility in oil, is further improved. Incidentally, the content of the structural unit (C) can be determined by calculation from the charged amount of the compound (C), which is a monomer for introducing the structural unit (C), as the raw material monomer of the polymer (x1).

[0075] The weight average molecular weight of the polymer (x1) is preferably from 10,000 to 500,000, more preferably from 30,000 to 400,000, and still more preferably from 40,000 to 300,000. If the weight average molecular weight of the polymer (x1) is at least the above lower limit value, the ability to improve the viscosity index is further enhanced. If the weight average molecular weight of the polymer (x1) is at most the above upper limit value, the solubility in oil, i.e., the solubility in oil, is further improved.

[0076] The number average molecular weight of the polymer (x1) is preferably from 5,000 to 50,000, more preferably from 8,000 to 40,000, and still more preferably from 10,000 to 30,000. If the weight average molecular weight of the polymer (x1) is at least the above lower limit value, the ability to improve the viscosity index is further enhanced. If the weight average molecular weight of the polymer (x1) is at most the above upper limit value, the solubility in oil, i.e., the solubility in oil, is further improved.

[0077] The polymer (x1) can be produced in the same manner as the polymer (X1) in the first aspect. That is, the polymer (x1) is preferably produced by polymerizing a monomer mixture (M1) containing the compound (A), the compound (B), and, if necessary, the compound (C) in a solvent by a known solution polymerization method.

[0078] The content of the polymer (x1) is preferably 0.1 to 99.9% by mass, more preferably 1 to 90% by mass, and still more preferably 2 to 70% by mass based on the total mass of the lubricant additive (Y1). If the content of the polymer (x1) is at least the above lower limit, the viscosity index improving ability and the solubility in oil are further improved. If the content of the polymer (x1) is at most the above upper limit, a significant thickening of the lubricating oil can be suppressed.

[0079] <Solvent> Examples of the solvent contained in the lubricant additive (Y1) include base oils such as paraffinic oils, naphthenic oils, and aromatic oils. Examples of the base oil include the base oils exemplified in the description of the method for producing the polymer (X1) of the first aspect. The solvent may be used alone or in combination of two or more.

[0080] The content of the solvent is preferably 0.1 to 99.9% by mass, more preferably 10 to 99% by mass, and still more preferably 30 to 98% by mass based on the total mass of the lubricant additive (Y1). If the content of the solvent is at least the above lower limit, a significant thickening of the lubricating oil can be suppressed. If the content of the solvent is at most the above upper limit, the viscosity index improving ability is further enhanced.

[0081] <Optional component> The lubricant additive (Y1) may further contain components other than the polymer (x1) and the solvent (hereinafter also referred to as "optional components") as necessary, as long as the effects of the present invention are not impaired. Examples of the optional components include detergents, dispersants, antioxidants, oiliness improvers, friction and wear modifiers, extreme pressure agents, antifoaming agents, demulsifiers, corrosion inhibitors, pour point depressants, rust inhibitors, emulsifiers, and fungicides. The optional components may be used alone or in combination of two or more.

[0082] <Production method> The lubricating oil additive (Y1) is obtained by mixing a polymer (x1), a solvent, and, if necessary, an optional component. For example, when the polymer (x1) is produced by a solution polymerization method using a base oil as the solvent, since the polymer (x1) produced in the solvent can be used as the lubricating oil additive (Y1) together with the solvent, it is preferable to obtain the lubricating oil additive (Y1) by producing the polymer (x1) in the solvent. That is, the production method of the lubricating oil additive (Y1) preferably includes a step of producing the polymer (x1) in the solvent. Note that the polymer solution in which the polymer (x1) is dissolved obtained by the solution polymerization method may be used as the lubricating oil additive (Y1) as it is, or the polymer solution may be further diluted with a solvent as necessary to be used as the lubricating oil additive (Y1).

[0083] <Use> The lubricating oil additive (Y1) is suitable as a viscosity index improver for lubricating oils.

[0084] "Fourth Aspect" The lubricating oil additive of the fourth aspect of the present invention (hereinafter, also referred to as "lubricating oil additive (Y2)") includes a polymer and a solvent.

[0085] <Polymer> The polymer (hereinafter, also referred to as "polymer (x2)") contained in the lubricating oil additive (Y2) includes a structural unit (A1) derived from myrcene and a structural unit (B) derived from the compound (B). The polymer (x2) may further include a structural unit (C) derived from the compound (C) in addition to the structural unit (A) and the structural unit (B), if necessary, as long as the effects of the present invention are not impaired. As the compound (B) and the compound (C), the compound (B) and the compound (C) exemplified above in the description of the polymer (X1) of the first aspect can be mentioned respectively.

[0086] The content of the constitutional unit (A1) is preferably 80 to 99.9% by mass, more preferably 85 to 99.5% by mass, still more preferably 90 to 99.5% by mass, particularly preferably 95 to 99.5% by mass, and most preferably 95 to 99% by mass, based on the total mass of all the constitutional units constituting the polymer (x2). If the content of the constitutional unit (A1) is at least the above lower limit value, the solubility in oil, i.e., the solubility in oil, is further improved. In addition, the polymer (x2) is less likely to gel. If the content of the constitutional unit (A1) is at most the above upper limit value, the ability to improve the viscosity index is further enhanced. Incidentally, the content of the constitutional unit (A1) can be determined by calculation from the charged amount of myrcene, which is a monomer for introducing the constitutional unit (A1), as the raw material monomer of the polymer (x2).

[0087] The polymer (x2) may contain only one type of constitutional unit (B) or may contain two or more types of constitutional units (B). The content of the constitutional unit (B) is 0.1 to 20% by mass, preferably 0.5 to 15% by mass, more preferably 0.5 to 10% by mass, still more preferably 0.5 to 5% by mass, and particularly preferably 1 to 5% by mass, based on the total mass of all the constitutional units constituting the polymer (x2). If the content of the constitutional unit (B) is at least the above lower limit value, the ability to improve the viscosity index is enhanced. If the content of the constitutional unit (B) is at most the above upper limit value, the solubility in oil, i.e., the solubility in oil, is improved. In addition, the polymer (x2) is less likely to gel. Incidentally, the content of the constitutional unit (B) can be determined by calculation from the charged amount of the compound (B), which is a monomer for introducing the constitutional unit (B), as the raw material monomer of the polymer (x2).

[0088] The polymer (x2) may contain only one type of constitutional unit (C) or may contain two or more types of constitutional units (C). The content of the structural unit (C) is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less, based on the total mass of all the structural units constituting the polymer (x2). If the content of the structural unit (C) is below the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is further improved. Incidentally, the content of the structural unit (C) can be determined by calculation from the charged amount of the compound (C), which is a monomer for introducing the structural unit (C), as a raw material monomer of the polymer (x2).

[0089] The weight average molecular weight of the polymer (x2) is preferably from 10,000 to 500,000, more preferably from 30,000 to 400,000, and still more preferably from 40,000 to 300,000. If the weight average molecular weight of the polymer (x2) is at least the above lower limit, the ability to improve the viscosity index is further enhanced. If the weight average molecular weight of the polymer (x2) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is further improved.

[0090] The number average molecular weight of the polymer (x2) is preferably from 5,000 to 50,000, more preferably from 8,000 to 40,000, and still more preferably from 10,000 to 30,000. If the weight average molecular weight of the polymer (x2) is at least the above lower limit, the ability to improve the viscosity index is further enhanced. If the weight average molecular weight of the polymer (x2) is at most the above upper limit, the solubility in oil, i.e., the ability to dissolve in oil, is further improved.

[0091] The polymer (x2) can be produced by the same method as the polymer (X2) of the second aspect. That is, the polymer (x2) is preferably produced by polymerizing a monomer mixture (M2) containing myrcene, the compound (B), and optionally the compound (C) in a solvent by a known solution polymerization method.

[0092] The content of the polymer (x2) is preferably 0.1 to 99.9% by mass, more preferably 1 to 90% by mass, and even more preferably 2 to 70% by mass based on the total mass of the lubricating oil additive (Y2). If the content of the polymer (x2) is at least the above lower limit, the viscosity index improvement ability and the solubility in oil are further improved. If the content of the polymer (x2) is at most the above upper limit, a significant thickening of the lubricating oil can be suppressed.

[0093] <Solvent> Examples of the solvent contained in the lubricating oil additive (Y2) include base oils such as paraffinic oils, naphthenic oils, and aromatic oils. Examples of the base oil include the base oils exemplified in the description of the method for producing the polymer (X1) of the first aspect. The solvent may be used alone or in combination of two or more.

[0094] The content of the solvent is preferably 0.1 to 99.9% by mass, more preferably 10 to 99% by mass, and even more preferably 30 to 98% by mass based on the total mass of the lubricating oil additive (Y2). If the content of the solvent is at least the above lower limit, a significant thickening of the lubricating oil can be suppressed. If the content of the solvent is at most the above upper limit, the viscosity index improvement ability is further enhanced.

[0095] <Optional component> The lubricating oil additive (Y2) may further contain components other than the polymer (x2) and the solvent (hereinafter also referred to as "optional components") in addition to the polymer (x2) and the solvent, as long as the effects of the present invention are not impaired. Examples of the optional components include the optional components exemplified above in the description of the lubricating oil additive (Y1) of the third aspect. The optional components may be used alone or in combination of two or more.

[0096] <Production method> The lubricating oil additive (Y2) is obtained by mixing the polymer (x2), the solvent, and, if necessary, the optional components. For example, when producing the polymer (x2) by a solution polymerization method using a base oil as a solvent, since the polymer (x2) produced in the solvent can be used as a lubricating oil additive (Y2) together with the solvent, it is preferable to obtain the lubricating oil additive (Y2) by producing the polymer (x2) in the solvent. That is, the method for producing the lubricating oil additive (Y2) preferably includes a step of producing the polymer (x2) in a solvent. In addition, the polymer solution in which the polymer (x2) obtained by the solution polymerization method is dissolved in the solvent may be directly used as the lubricating oil additive (Y2), or the polymer solution may be further diluted with a solvent as necessary to be used as the lubricating oil additive (Y2).

[0097] <Use> The lubricating oil additive (Y2) is suitable as a viscosity index improver for lubricating oils.

[0098] "Fifth Aspect" The lubricating oil additive of the fifth aspect of the present invention (hereinafter, also referred to as "lubricating oil additive (Y3)") includes the above-described polymer (X1) and a solvent.

[0099] <Polymer (X1)> Since the polymer (X1) contained in the lubricating oil additive (Y3) is the same as the polymer (X1) of the first aspect, the description thereof is omitted. The content of the polymer (X1) is preferably 0.1 to 99.9% by mass, more preferably 1 to 90% by mass, and even more preferably 2 to 70% by mass with respect to the total mass of the lubricating oil additive (Y3). If the content of the polymer (X1) is at least the above lower limit value, the viscosity index improving ability and the solubility in oil are further improved. If the content of the polymer (X1) is at most the above upper limit value, a significant thickening of the lubricating oil can be suppressed.

[0100] <Solvent> Examples of the solvent contained in the lubricating oil additive (Y3) include base oils such as paraffinic oils, naphthenic oils, and aromatic oils. Examples of the base oil include the base oils exemplified in the description of the method for producing the polymer (X1) of the first aspect. The solvent may be used alone or in combination of two or more kinds.

[0101] The content of the solvent is preferably 0.1 to 99.9% by mass, more preferably 10 to 99% by mass, and still more preferably 30 to 98% by mass based on the total mass of the lubricating oil additive (Y3). If the content of the solvent is at least the above lower limit value, a significant thickening of the lubricating oil can be suppressed. If the content of the solvent is at most the above upper limit value, the viscosity index improvement ability is further enhanced.

[0102] <Optional component> The lubricating oil additive (Y3) may further contain components other than the polymer (X1) and the solvent (hereinafter also referred to as "optional components") as necessary, as long as the effects of the present invention are not impaired. Examples of the optional components include the optional components exemplified above in the description of the lubricating oil additive (Y1) of the third aspect. The optional components may be used alone or in combination of two or more kinds.

[0103] <Production method> The lubricating oil additive (Y3) can be obtained by mixing the polymer (X1), the solvent, and, if necessary, the optional components. For example, when the polymer (X1) is produced by a solution polymerization method using a base oil as the solvent, since the polymer (X1) produced in the solvent can be used as the lubricating oil additive (Y3) together with the solvent, it is preferable to obtain the lubricating oil additive (Y3) by producing the polymer (X1) in the solvent. That is, the production method of the lubricating oil additive (Y3) preferably includes a step of producing the polymer (X1) in the solvent. In addition, the polymer solution in which the polymer (X1) is dissolved and obtained by the solution polymerization method may be used as it is as the lubricating oil additive (Y3), or may be further diluted with a solvent as necessary to be used as the lubricating oil additive (Y3).

[0104] <Use> The lubricating oil additive (Y3) is suitable as a viscosity index improver for lubricating oils.

[0105] "Sixth Aspect" The lubricating oil additive of the sixth aspect of the present invention (hereinafter, also referred to as "lubricating oil additive (Y4)") contains the above-described polymer (X2) and a solvent.

[0106] <Polymer (X2)> Since the polymer (X2) contained in the lubricating oil additive (Y4) is the same as the polymer (X2) of the second aspect, the description thereof is omitted. The content of the polymer (X2) is preferably 0.1 to 99.9% by mass, more preferably 1 to 90% by mass, and still more preferably 2 to 70% by mass with respect to the total mass of the lubricating oil additive (Y4). If the content of the polymer (X2) is at least the above lower limit value, the viscosity index improvement ability and the solubility in oil are further improved. If the content of the polymer (X2) is at most the above upper limit value, a significant thickening of the lubricating oil can be suppressed.

[0107] <Solvent> Examples of the solvent contained in the lubricating oil additive (Y4) include base oils such as paraffinic oils, naphthenic oils, and aromatic oils. Examples of the base oil include the base oils exemplified in the description of the production method of the polymer (X1) of the first aspect. The solvent may be used alone or in combination of two or more.

[0108] The content of the solvent is preferably 0.1 to 99.9% by mass, more preferably 10 to 99% by mass, and still more preferably 30 to 98% by mass with respect to the total mass of the lubricating oil additive (Y4). If the content of the solvent is at least the above lower limit value, a significant thickening of the lubricating oil can be suppressed. If the content of the solvent is at most the above upper limit value, the viscosity index improvement ability is further enhanced.

[0109] <Optional Component> The lubricating oil additive (Y4) may further contain components other than the polymer (X2) and the solvent (hereinafter, also referred to as "optional components") as necessary, as long as the effects of the present invention are not impaired. Examples of optional components include those exemplified above in the description of the lubricating oil additive (Y1) of the third aspect. The optional components may be used alone or in combination of two or more.

[0110] <Manufacturing method> The lubricating oil additive (Y4) is obtained by mixing the polymer (X2), a solvent, and optional components as necessary. For example, when the polymer (X2) is produced by a solution polymerization method using a base oil as a solvent, the polymer (X2) produced in the solvent can be used as the lubricating oil additive (Y4) together with the solvent. Therefore, it is preferable to obtain the lubricating oil additive (Y4) by producing the polymer (X2) in a solvent. That is, the manufacturing method of the lubricating oil additive (Y4) preferably includes a step of producing the polymer (X2) in a solvent. Note that the polymer solution in which the polymer (X2) is dissolved obtained by the solution polymerization method may be used as it is as the lubricating oil additive (Y4), or may be further diluted with a solvent as necessary to be used as the lubricating oil additive (Y4).

[0111] <Use> The lubricating oil additive (Y4) is suitable as a viscosity index improver for lubricating oils.

[0112] [Viscosity index improver] The viscosity index improver of the seventh aspect of the present invention includes any of the above-described lubricating oil additives of the present invention, that is, the lubricating oil additive (Y1) of the third aspect, the lubricating oil additive (Y2) of the fourth aspect, the lubricating oil additive (Y3) of the fifth aspect, and the lubricating oil additive (Y4) of the sixth aspect. The viscosity index improver may further contain components other than the lubricating oil additive of the present invention (hereinafter also referred to as "optional components") as necessary, as long as the effects of the present invention are not impaired. Examples of optional components include those exemplified above in the description of the lubricating oil additive (Y1) of the third aspect. Any component may be used alone or in combination of two or more kinds.

[0113] The viscosity index improver is preferably such that the degree of increase in kinematic viscosity due to addition is large at high temperatures and small at low temperatures. Generally, a viscosity index improver composed of a (meth)acrylate polymer forms a fine particle structure without completely dissolving at low temperatures, and as the temperature rises, the solubility improves, the polymer chains expand, and it is known to exhibit the above-mentioned function. As an index of the performance of the viscosity index improver, a viscosity index calculated from the kinematic viscosities at low temperature (for example, 40 °C) and high temperature (for example, 100 °C) is used.

[0114] The viscosity index is a value measured in accordance with JIS K 2283:2000, and the larger the numerical value, the smaller the viscosity change due to temperature. In recent years, for viscosity index improvers, higher numerical values have also been required for the viscosity (HTHS150 °C viscosity) under conditions of higher temperature (150 °C) and higher shear. Therefore, it is preferable that it does not completely dissolve even at 100 °C and the viscosity improvement effect can be expected even at higher temperatures. The dissolution state at 100 °C can be evaluated, for example, by small-angle X-ray scattering measurement (SAXS).

[0115] Since the viscosity index improver of the seventh aspect contains any of the lubricant additives of the present invention described above, it has excellent viscosity index improving ability. Specifically, the viscosity index measured by the method described in the examples below is likely to be 140 to 250. A viscosity index of 150 to 200 is more preferable. If the viscosity index is within the above range, the fuel consumption of vehicles and the like can be reduced.

[0116] [Lubricating oil] The lubricating oil of the eighth aspect of the present invention contains any of the lubricant additives of the present invention described above, that is, any of the lubricant additives (Y1) of the third aspect, the lubricant additives (Y2) of the fourth aspect, the lubricant additives (Y3) of the fifth aspect, and the lubricant additives (Y4) of the sixth aspect. The lubricating oil may further contain, if necessary, components other than the lubricating oil additive of the present invention (hereinafter also referred to as "optional components") within a range not impairing the effects of the present invention, in addition to the lubricating oil additive of the present invention. Examples of the optional components include the optional components exemplified above in the description of the lubricating oil additive (Y1) of the third aspect. The optional components may be used alone or in combination of two or more.

[0117] When the lubricating oil contains the lubricating oil additive (Y1), the content of the polymer (x1) contained in the lubricating oil is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and still more preferably 0.1 to 20% by mass based on the total mass of the lubricating oil. If the content of the polymer (x1) is at least the above lower limit value, the viscosity index of the lubricating oil is improved. If the content of the polymer (x1) is at most the above upper limit value, the kinematic viscosity of the lubricating oil at low temperatures is suppressed and the fuel consumption is improved. The content of the polymer (x2) in the lubricating oil when the lubricating oil contains the lubricating oil additive (Y2), the content of the polymer (X1) in the lubricating oil when the lubricating oil contains the lubricating oil additive (Y3), and the content of the polymer (X2) in the lubricating oil when the lubricating oil contains the lubricating oil additive (Y4) are the same as the content of the polymer (x1).

[0118] The lubricating oil is suitable as various lubricating oils such as engine oil, gear oil, hydraulic oil, drive system lubricating oil, and automatic transmission oil used in mobility such as industrial machines, robots, and automobiles.

Examples

[0119] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as it does not exceed the gist thereof, and various modifications are possible without departing from the gist of the present invention. The measurement and evaluation methods are shown below.

[0120] <Calculation of the content of constitutional units> The content of each constitutional unit in the polymer was calculated from the charged amount of the monomer. The content of the structural unit (A1) with respect to the total mass of the polymer was calculated from the charged amount of myrcene corresponding to the compound (A). The content of the structural unit (B) with respect to the total mass of the polymer was calculated from the charged amount of the compound (B) or its substitute. The content of the structural unit (C) with respect to the total mass of the polymer was calculated from the charged amount of the compound (C).

[0121] <Measurement of weight-average molecular weight (Mw) and number-average molecular weight (Mn)> The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer were determined as molecular weights in terms of standard polystyrene by GPC (gel permeation chromatography). Specifically, after preparing a tetrahydrofuran solution of the polymer solution, it was injected into an apparatus equipped with the separation column shown below, and the molecular weight of the polymer was measured under the measurement conditions shown below, and the mass-average molecular weight (Mw) and number-average molecular weight (Mn) were calculated in terms of standard polystyrene. · Apparatus: Product name "HLC-8220" manufactured by Tosoh Corporation, · Separation column: Product name "TSK-GEL SUPER HM-H" manufactured by Tosoh Corporation, exclusion limit molecular weight = 4×10 8 , inner diameter 6.0 mm, length 150 mm, · Detector: RI (differential refractometer), UV, · Eluent: Tetrahydrofuran (THF), · Flow rate: 0.600 ml / min, · Sample concentration: 0.02 g / 10 mL, · Column temperature: 40 °C.

[0122] <Evaluation of solubility> The transparency of the diluted solution obtained by further diluting the polymer solution with a diluent so that the polymer concentration was 5% by mass was visually confirmed, and the solubility of the polymer in the base oil was evaluated according to the following evaluation criteria. 〇: Transparent. ×: Opaque or insoluble matter is precipitated.

[0123] <Measurement of viscosity index (VI)> For the polymer solution, the kinematic viscosity at 40°C (Vk40) and the kinematic viscosity at 100°C (Vk100) were measured in accordance with JIS K 2283:2000. Using the obtained "Vk40" and "Vk100", the viscosity index (VI) was calculated in accordance with JIS K 2283:2000. The viscosity index is a physical property value representing the temperature dependence of the viscosity of lubricating oil.

[0124] [Example 1] Into a dried Schlenk tube, 33.3 parts by mass of a lubricating oil base oil (manufactured by SK Lubricants Co., Ltd., trade name "YUBASE4"), 98 parts by mass of millicene (manufactured by Yasuhara Chemical Co., Ltd.), and 2 parts by mass of 1,3-butanediol dimethacrylate were charged. After thoroughly replacing the inside of the Schlenk tube with nitrogen, the liquid temperature was raised to 100°C. Then, 10.0 parts by mass of 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name "PEROCTA O") was added as a radical polymerization initiator, and the reaction was carried out for 10 hours to obtain a polymer solution containing 75% by mass of the polymer, which was used as a lubricating oil additive. For the obtained polymer solution, the molecular weight and viscosity index of the polymer were measured. Also, the polymer solution was diluted with the dilution solvents shown in Table 1 to evaluate the solubility. The results are shown in Table 1.

[0125] [Examples 2 to 16, Comparative Examples 1 to 3] The amounts of millicene, compound (B) or its substitute, and compound (C) were changed so that the types and contents of the structural units (A1), (B), and (C) constituting the polymer became the values shown in Tables 1 and 2. Also, except that the addition amount of PEROCTA O was changed to the value shown in Table 1, the polymer solution was produced in the same manner as in Example 1, and various measurements and evaluations were performed. The results are shown in Tables 1 and 2.

[0126]

Table 1

[0127]

Table 2

[0128] The abbreviations in Tables 1 and 2 are as follows. · 1,3-BDMA: 1,3-butanediol dimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), · ADE-400A: polyethylene glycol diacrylate (manufactured by NOF Corporation, where R 2 and R 4 are hydrogen atoms, R 3 is an ethylene group, and n is 9 (compound (B))), · PDE-400: polyethylene glycol dimethacrylate (manufactured by NOF Corporation, where R 2 and R 4 are methyl groups, R 3 is an ethylene group, and n is 9 (compound (B))), · PDP-400N: polypropylene glycol dimethacrylate (manufactured by NOF Corporation, where R 2 and R 4 are methyl groups, R 3 is a propylene group, and n is 7 (compound (B))), · AMA: allyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd., substitute for compound (B)), · 4HBA: 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., compound (C)), · PP-800: polypropylene glycol monomethacrylate (manufactured by NOF Corporation, compound (C)), · AA: acrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd., compound (C)), · PeroctO: 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation), · YUBASE4: API Group III+ mineral base oil (manufactured by SK Lubricants Co., Ltd.), · PAO170: polyalphaolefin (manufactured by INEOS Oligomers, trade name "DURASYN170", synthetic chemical oil). Note that allyl methacrylate corresponds to compound (C), but it was used as a substitute for compound (B) in Comparative Example 1.

[0129] As is clear from Tables 1 and 2, the lubricant additives, which are polymer solutions obtained in each Example, were excellent in solubility in the base oil and had good kinematic viscosity and viscosity index. The lubricant additives, which are polymer solutions obtained in Comparative Examples 1 and 2 that do not contain constitutional unit (B), had low kinematic viscosity and viscosity index. Since the polymer solution obtained in Comparative Example 3 gelled, the molecular weight, kinematic viscosity, and viscosity index could not be measured.

Industrial Applicability

[0130] The lubricant additive of the present invention is excellent in viscosity index improvement ability and solubility in oil, and is suitable as an additive to be added to various lubricating oils such as engine oil, gear oil, hydraulic oil, drive system lubricating oil, and automatic transmission oil used in the mobility of industrial machines, robots, automobiles, etc.

Claims

1. A lubricant additive comprising a polymer and a solvent, wherein the polymer comprises a structural unit (A) derived from a compound represented by the following general formula (1) and a structural unit (B) derived from a (meth)acryloyl group-containing compound, wherein the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, and the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer. 【Chemical 1】 (In general formula (1), R １ is a group represented by C ｎ H ２ｎ＋ｍ , n is an integer from 1 to 30, m is any one of -3, -1, and 1, and 2n + m is an integer of 3 or more.)

2. The polymer further comprises a structural unit (C) (excluding the structural unit (B)) derived from a (meth)acryloyl group-containing compound having at least one functional group selected from an alkyl group, a hydroxy group, a silyloxy group, a vinyl group, an ether group, an amino group, a carboxy group, a fluorine atom, and a phosphate group. The lubricant additive according to claim 1.

3. In the general formula (1), n is an integer of 2 to 11, m is -3 or -1, and 2n + m is an integer of 3 to 19. The lubricant additive according to claim 1.

4. In the general formula (1), n is an integer of 6 to 11, and m is -3 or -1. The lubricant additive according to claim 1.

5. In the general formula (1), R １ is a group represented by C ６ H １１ The lubricating oil additive according to claim 1.

6. The (meth)acryloyl group-containing compound comprises a compound represented by the following general formula (2). The lubricant additive according to claim 1. CH ２ =CR ２ -COO-(R ３ O) ｎ -COCR ４ =CH ２ ...(2) (In general formula (2), R ２ and R ４ are each independently a hydrogen atom or a methyl group, R ３ is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

7. A lubricant additive comprising a polymer and a solvent, wherein the polymer comprises a structural unit (A1) derived from myrcene and a structural unit (B) derived from a (meth)acryloyl group-containing compound, wherein the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, and the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer.

8. The (meth)acryloyl group-containing compound comprises a compound represented by the following general formula (2). The lubricant additive according to claim 7. CH ２ =CR ２ -COO-(R ３ O) ｎ -COCR ４ =CH ２ ...(2) (In general formula (2), R ２ and R ４ are each independently a hydrogen atom or a methyl group, R ３ is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

9. A polymer comprising a structural unit (A) derived from a compound represented by the following general formula (1) and a structural unit (B) derived from a (meth)acryloyl group-containing compound, wherein the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units, and the weight average molecular weight is 10,000 to 500,000. 【Chemical 2】 (In the general formula (1), R １ is a group represented by C ｎ H ２ｎ＋ｍ , n is an integer from 1 to 30, m is any one of -3, -1, and 1, and 2n + m is an integer of 3 or more.)

10. In the general formula (1), n is an integer from 2 to 11, m is -3 or -1, and 2n + m is an integer from 3 to 19. The polymer according to claim 9.

11. In the general formula (1), n is an integer from 6 to 11, and m is -3 or -1. The polymer according to claim 9.

12. In the general formula (1), R １ is a group represented by C ６ H １１ The polymer according to claim 9, which is a group represented by

13. The (meth)acryloyl group-containing compound includes a compound represented by the following general formula (2). The polymer according to claim 9. CH ２ =CR ２ -COO-(R ３ O) ｎ -COCR ４ =CH ２ ...(2) (In general formula (2), R ２ and R ４ are each independently a hydrogen atom or a methyl group, R ３ is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

14. A lubricating oil additive comprising the polymer according to claim 9 and a solvent.

15. Comprising a structural unit (A1) derived from myrcene and a structural unit (B) derived from a (meth)acryloyl group-containing compound, The (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, Based on the total mass of all the structural units, the content of the structural unit (B) is 0.1 to 20% by mass, A polymer having a weight average molecular weight of 10,000 to 500,000.

16. The (meth)acryloyl group-containing compound includes a compound represented by the following general formula (2). The polymer according to claim 15. CH ２ =CR ２ -COO-(R ３ O) ｎ -COCR ４ =CH ２ ...(2) (In general formula (2), R ２ and R ４ are each independently a hydrogen atom or a methyl group, R ３ is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more.)

17. A lubricating oil additive comprising the polymer according to claim 15 and a solvent.

18. The solvent includes at least one of mineral oil and synthetic chemical oil. The lubricating oil additive according to any one of claims 1 to 8, 14, and 17.

19. A viscosity index improver comprising the lubricating oil additive according to any one of claims 1 to 8, 14, and 17.

20. A lubricating oil comprising the lubricating oil additive according to any one of claims 1 to 8, 14, and 17.

21. Including the step of producing a polymer in a solvent, The polymer includes a structural unit (A) derived from a compound represented by the following general formula (1) and a structural unit (B) derived from a (meth)acryloyl group-containing compound, The (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, Based on the total mass of all the structural units constituting the polymer, the content of the structural unit (B) is 0.1 to 20% by mass. A method for producing a lubricating oil additive. 【Chemical Formula 3】 (In the general formula (1), R １ is a group represented by C ｎ H ２ｎ＋ｍ , n is an integer from 1 to 30, m is any one of -3, -1, and 1, and 2n + m is an integer of 3 or more.)

22. Including the step of producing a polymer in a solvent, The polymer includes a structural unit (A1) derived from myrcene and a structural unit (B) derived from a (meth)acryloyl group-containing compound, The (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, A method for producing a lubricant additive, wherein the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer.

23. including a step of producing a polymer in a solvent, the polymer includes a structural unit (A) derived from a compound represented by the following general formula (1) and a structural unit (B) derived from a (meth)acryloyl group-containing compound, the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer, and the weight average molecular weight of the polymer is 10,000 to 500,000. A method for producing a lubricant additive. 【Chemical Formula 4】 (In general formula (1), R １ is a group represented by C ｎ H ２ｎ＋ｍ , n is an integer from 1 to 30, m is any one of -3, -1, and 1, and 2n + m is an integer of 3 or more.)

24. including a step of producing a polymer in a solvent, the polymer includes a structural unit (A1) derived from myrcene and a structural unit (B) derived from a (meth)acryloyl group-containing compound, the (meth)acryloyl group-containing compound has two or more (meth)acryloyl groups, the content of the structural unit (B) is 0.1 to 20% by mass based on the total mass of all the structural units constituting the polymer, and the weight average molecular weight of the polymer is 10,000 to 500,000. A method for producing a lubricant additive.

25. The method for producing a lubricant additive according to any one of claims 21 to 24, wherein the solvent contains at least one of mineral oil and synthetic chemical oil.

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