Lubricant additives and lubricant compositions

Abstract

To provide a lubricant additive with an enhanced friction reduction effect, and a lubricant composition.SOLUTION: A lubricant additive comprises a (meth)acrylic graft copolymer A comprising (a) a constitutional unit derived from a vinyl monomer with a fluorine atom, and a lubricant composition comprises the lubricant additive.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to lubricating oil additives and lubricating oil compositions used in lubricating oils. [Background technology]

[0002] Lubricants, such as those used in automobile engines and drivetrains, 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 important. Examples of friction-reducing agents 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 organic molybdenum compounds. However, depending on the usage conditions and environment, these additives alone may not provide sufficient friction reduction. To overcome this challenge, research is underway to use polymer materials as friction-reducing agents. For example, Patent Document 1 discloses that a lubricating oil composition containing a copolymer comprising a (meth)acryloyl monomer having a fluoroalkyl group and a (meth)acryloyl monomer having a linear or branched alkyl group having 1 to 36 carbon atoms exhibits excellent friction reduction effects. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-172701 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the method described in Patent Document 1 is insufficient in reducing friction. The object of the present invention is to provide a lubricating oil additive and a lubricating oil composition that have excellent friction reduction effects. [Means for solving the problem]

[0005] The present invention has the following aspects. [1] A lubricating oil additive containing a (meth)acrylic graft copolymer A that includes constituent units derived from (meth)acrylate (a) having a fluorine atom. [2] The lubricating oil additive according to [1], wherein the (meth)acrylate (a) having a fluorine atom comprises a (meth)acrylate represented by the following formula (1).

[0006] [ka]

[0007] (In the formula, R 1 is a hydrogen atom or a methyl group, -R 2 - is -(CH2) p - or -CH2CH(OH)CH2- is a group where p is 0 to 4, R 3 (This represents a linear or branched alkyl group having 1 to 10 carbon atoms, in which one or more hydrogen atoms are replaced by fluorine atoms.) [3] The lubricating oil additive according to [1] or [2], wherein the (meth)acrylic graft copolymer A further comprises a constituent unit derived from alkyl (meth)acrylate (b) having a linear or branched alkyl group. [4] The lubricating oil additive according to [3], wherein the alkyl(meth)acrylate(b) has 1 to 20 carbon atoms in the alkyl group. [5] The lubricating oil additive according to any one of [1] to [4], wherein the (meth)acrylic graft copolymer A comprises a constituent unit derived from a vinyl radical polymerizable monomer (m1) and a constituent unit derived from a macromonomer (M). [6] The lubricating oil additive according to [5], wherein the macromonomer (M) comprises a constituent unit derived from a vinyl radical polymerizable monomer (m2). [7] The lubricant additive according to [5], wherein the macromonomer (M) has a structure represented by the following formula (2).

[0008]

Chemical formula

[0009] (In the formula, X 1 ~X n-1 each independently represents a hydrogen atom, a methyl group or CH2OH, and Y 1 ~Y n each independently represents a substituent other than X 1 ~X n-1 that binds to the vinyl group of the vinyl-based radically polymerizable monomer (m2) which is a monomer of the macromonomer (M). Z represents a terminal group, and n represents an integer of 2 to 10,000.) [8] The lubricant additive according to any one of [1] to [7], wherein the mass average molecular weight of the (meth)acrylic graft copolymer A is 5,000 to 200,000. [9] The lubricant additive according to any one of [1] to [8], which is a friction reducer for lubricating oil.

[10] A lubricant composition containing the lubricant additive according to any one of [1] to [9].

Advantages of the Invention

[0010] According to the present invention, a lubricant additive and a lubricant composition excellent in friction reduction effect can be provided.

Modes for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in detail. The following embodiments are merely illustrative 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. [[ID=​​In this invention, "(meth)acrylic" is a general term for "acrylic" and "methacrylic". "(meth)acrylate" is a general term for "acrylate" and "methacrylate". "(meth)acryloyl group" is a general term for "acryloyl group" and "methacryloyl group", and is a group represented by CH2=C(R)-C(=O)-(R is a hydrogen atom or a methyl group). "Macromonomer" means a polymer having a radical polymerizable group or an addition-reactive functional group. "Vinyl radical polymerizable monomer" means a monomer having an ethylenically unsaturated bond that is not a macromonomer.

[0013] The lubricating oil additive of the present invention contains (meth)acrylic graft copolymer A. (Meth)acrylic graft copolymer A is a graft copolymer in which at least a portion of the constituent units are derived from (meth)acrylic monomers. (Meth)acrylic graft copolymer A may further contain constituent units derived from monomers other than (meth)acrylic monomers (e.g., styrene).

[0014] (Meth)acrylic graft copolymer A is a graft copolymer composed of a main chain polymer structure and side chain polymer structures (branch polymer structures) that are chemically bonded to the main chain polymer structure (stem polymer structure). In this specification, a graft copolymer is a polymer having a main chain polymer structure to which one or more blocks are connected as side chain polymer structures. The structures of the main chain polymer and the side chain polymer may be different or the same. There are no particular limitations on the method for producing a graft copolymer, but examples include a method in which a macromonomer having a radically polymerizable double bond at its terminal is produced as a side chain polymer structure, and then radically polymerized with monomers that will become the constituent units of the main chain polymer; a method in which a main chain polymer having a reaction site and a macromonomer having a reaction site are produced in advance and then reacted; and a method in which, after producing the main chain polymer, a hydrogen abstraction initiator is used to generate radicals on the main chain polymer, and then monomers that will become the constituent units of the side chain polymer are reacted to produce the side chain polymer structure.

[0015] (Meth)acrylic graft copolymer A contains constituent units derived from (meth)acrylate (a) having a fluorine atom (hereinafter also referred to as "component (a)"). It may further contain constituent units derived from alkyl (meth)acrylate (b) having a linear or branched alkyl group (hereinafter also referred to as "component (b)").

[0016] It is preferable that the total mass of the (meth)acrylic graft copolymer A contains 70% by mass or more of components (a) and (b) as constituent units, more preferably 75% by mass or more, and even more preferably 80% by mass or more.

[0017] Examples of component (a) include 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,3,3,3-pentafluoropropyl (meth)acrylate, 1,1,1,3,3,3-hexafluoroisopropyl (meth)acrylate, 1H,1H,3H-hexafluorobutyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,2H,2H-nonylfluorohexyl (meth)acrylate, 1H,1H,6H-decafluorohexyl (meth)acrylate, 1H,1H,2H,2H,7H-decafluoroheptyl (meth)acrylate, and 1H,1H,2H,4 Examples include H,7H-decafluoroheptyl (meth)acrylate, 1H,1H,7H-dodecafluoroheptyl (meth)acrylate, 1H,1H,2H,2H-undecafluoro-5-methylhexyl (meth)acrylate, 1H,1H,2H,2H-tridecafluorooctyl (meth)acrylate, 1H,1H,9H-hexadecafluorononyl (meth)acrylate, 1H,1H-nonadecafluorodecyl (meth)acrylate, 1H,1H-undecafluorocyclohexyl (meth)acrylate, pentafluorophenyl (meth)acrylate, pentafluorobenzyl (meth)acrylate, and 3-perfluorohexyl-2-hydroxypropyl (meth)acrylate. Two or more of these may be used in combination.

[0018] From the standpoint of achieving high solubility in the base oil, component (a) is preferably a (meth)acrylate represented by the following formula (1): 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,3,3,3-pentafluoropropyl (meth)acrylate, 1,1,1,3,3,3-hexafluoroisopropyl (meth)acrylate, 1H,1H,3H-hexafluorobutyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, and 1H,1H,2H,2H-nonylfluorohexyl (meth)acrylate. 1H,1H,6H-decafluorohexyl (meth)acrylate, 1H,1H,2H,2H,7H-decafluoroheptyl (meth)acrylate, 1H,1H,2H,4H,7H-decafluoroheptyl (meth)acrylate, 1H,1H,7H-dodecafluoroheptyl (meth)acrylate, 1H,1H,2H,2H-undecafluoro-5-methylhexyl (meth)acrylate, 1H,1H,2H,2H-tridecafluorooctyl (meth)acrylate, 1H,1H,9H-hexadecafluorononyl (meth)acrylate, and 1H,1H-nonadecafluorodecyl (meth)acrylate are more preferred.

[0019] [ka]

[0020] (In the formula, R 1 is a hydrogen atom or a methyl group, -R 2 - is -(CH2) p - or -CH2CH(OH)CH2- is a group where p is 0 to 4, R 3 (This represents a linear or branched alkyl group having 1 to 10 carbon atoms, in which one or more hydrogen atoms are replaced by fluorine atoms.) In the above general formula (1), R 1 is a hydrogen atom or a methyl group. "-R 2 -」 is -(CH2) pIt is represented as - or -CH2CH(OH)CH2-, and is a group with p from 0 to 4, such as the methylene group, ethylene group, propylene group, butylene group, 2-hydroxypropylene group, etc. When p is 0, it is "-(CH2) p The hyphen "-" indicates a single conjunction. R 3 This is a linear or branched alkyl group having 1 to 10 carbon atoms in which one or more hydrogen atoms are replaced with fluorine atoms, for example, 2,2,2-trifluoroethyl group, 2,2,3,3-tetrafluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoroisopropyl group, 1H,1H,3H-hexafluorobutyl group, 1H,1H,5H-octafluoropentyl group, 1H,1H,2H,2H-nonylfluorohexyl Examples include the groups 1H,1H,6H-decafluorohexyl, 1H,1H,2H,2H,7H-decafluoroheptyl, 1H,1H,2H,4H,7H-decafluoroheptyl, 1H,1H,7H-dodecafluoroheptyl, 1H,1H,2H,2H-undecafluoro-5-methylhexyl, 1H,1H,2H,2H-tridecafluorooctyl, 1H,1H,9H-hexadecafluorononyl, and 1H,1H-nonadecafluorodecyl.

[0021] (a) The constituent units derived from component (meth)acrylic graft copolymer A are preferably in an amount of 0.05 to 40% by mass, more preferably 0.1 to 30% by mass, and even more preferably 0.2 to 20% by mass, based on the total mass of the (meth)acrylic graft copolymer A, in order to enhance the friction reduction effect. The (meth)acrylic graft copolymer A may contain constituent units derived from component (a) in both the side-chain polymer structure and the main-chain polymer structure. It is preferable to include the constituent units derived from component (a) in the side-chain polymer structure in order to enhance the friction reduction effect.

[0022] Specific examples of component (b) 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, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, n-pentadecyl (meth)acrylate, n-cetyl (meth)acrylate, n-heptadecyl (meth)acrylate, and n-stearyl (meth)acrylate. Examples include alkyl(meth)acrylates having linear alkyl groups such as acrylate; and alkyl(meth)acrylates having branched alkyl groups such as i-propyl(meth)acrylate, i-butyl(meth)acrylate, t-butyl(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, and 2-ethylhexyl(meth)acrylate.

[0023] (b) As for component (b), alkyl(meth)acrylates with 1 to 20 carbon atoms in the alkyl group are preferred, alkyl(meth)acrylates with 2 to 18 carbon atoms in the alkyl group are more preferred, and alkyl(meth)acrylates with 4 to 14 carbon atoms in the alkyl group are particularly preferred, in order to improve solubility in the base oil.

[0024] (b) The constituent units derived from component are preferably in an amount of 60 to 99.95% by mass, more preferably 70 to 99.9% by mass, and even more preferably 80 to 99.8% by mass, relative to the total mass of (meth)acrylic graft copolymer A, in order to improve solubility in the base oil.

[0025] The (meth)acrylic graft copolymer A may contain constituent units derived from component (b) in both the side-chain polymer structure and the main-chain polymer structure as constituent units. From the viewpoint of increasing solubility in base oil, it is preferable to contain alkyl methacrylates with 1 to 20 C1 of the alkyl group in the side-chain polymer structure, more preferably alkyl methacrylates with 2 to 18 C1 of the alkyl group, and even more preferably alkyl methacrylates with 4 to 14 C1 of the alkyl group. Furthermore, from the viewpoint of increasing the friction reduction effect, it is preferable to contain alkyl acrylates with 1 to 20 C1 of the alkyl group in the main-chain polymer structure, more preferably alkyl acrylates with 2 to 18 C1 of the alkyl group, and even more preferably alkyl acrylates with 4 to 14 C1 of the alkyl group.

[0026] The (meth)acrylic graft copolymer A may contain constituent units derived from other radical polymerizable vinyl compounds other than components (a) and (b) (hereinafter also referred to as "component (c)"). Examples of component (c) include styrene, α-methylstyrene, pt-butylstyrene, vinyltoluene, vinyl acetate, and (meth)acrylate compounds other than components (a) and (b).

[0027] (a) Other (meth)acrylate compounds include cyclic alkyl group (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and 4-t-butylcyclohexyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-t-butyl (meth)acrylate. (meth)acrylates having hydroxyl groups such as acrylate, 6-hydroxyhexyl (meth)acrylate, glycerin mono(meth)acrylate, ethylene glycol mono(meth)acrylate, propylene glycol mono(meth)acrylate; (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, etc. (meth)acrylate; phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene glycol (meth)acrylate, phenylphenyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate (meth)acrylates having an aromatic ring structure such as phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, and (1-naphthyl)methyl (meth)acrylate; (meth)acrylates having a heterocyclic structure such as tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, and (meth)acrylate oil morpholine; alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and butoxyethyl (meth)acrylate;Examples include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and (meth)acrylamide. Two or more of these may be used in combination.

[0028] From the standpoint of achieving a higher friction reduction effect, the content of constituent units derived from component (c) relative to the total mass of (meth)acrylic graft copolymer A is preferably 0.01 to 30% by mass, more preferably 0.03 to 20% by mass, and even more preferably 0.5 to 10% by mass. Note that (meth)acrylic graft copolymer A does not necessarily have to contain constituent units derived from component (c). The (meth)acrylic graft copolymer A may contain the constituent units derived from component (c) in the side chain polymer structure or in the main chain polymer structure. The total amount of constituent units derived from components (a) to (c) above shall not exceed 100% by mass of the total mass of the (meth)acrylic graft copolymer A.

[0029] The (meth)acrylic graft copolymer A may contain constituent units derived from a vinyl radical polymerizable monomer (m1) (hereinafter also referred to as "(m1) component") and constituent units derived from a macromonomer (M) (hereinafter also referred to as "(M) component").

[0030] Examples of component (m1) include the compounds listed as components (a) to (c). Two or more of these may be used in combination. It is preferable that component (m1) contains a (meth)acrylate compound from the viewpoint of excellent radical polymerization properties. From the viewpoint of being able to enhance the friction reduction effect, alkyl acrylates with 1 to 20 C1 of the alkyl group are preferred as component (m1), alkyl acrylates with 2 to 18 C1 of the alkyl group are more preferred, and alkyl acrylates with 4 to 14 C1 of the alkyl group are even more preferred.

[0031] The (M) component is not particularly limited as long as it is a compound having a radical polymerizable group and a repeating structure. Examples include compounds obtained by modifying the terminals of polyisobutylene or hydrogenated polybutadiene with vinyl-based radical polymerizable groups, and compounds containing two or more constituent units derived from a monomer (m2) having a vinyl-based radical polymerizable group (hereinafter also referred to as "(m2) component") and having a radical polymerizable group at its terminal. Due to the high degree of design for solubility in base oil, it is preferable that the (m2) component contains two or more constituent units and has a radical polymerizable group at its terminal. It is preferable that the (m2) component contains the (b) component, and more preferably contains both the (b) component and the (c) component. Two or more macromonomers M may be used in combination.

[0032] Examples of component (m2) include the compounds listed as components (a) to (c) above. It is preferable that component (m2) contains a (meth)acrylate compound due to its excellent radical polymerization properties. From the standpoint of achieving high solubility in the base oil, the (m2) component is preferably an alkyl methacrylate with 1 to 20 carbon atoms in the alkyl group, more preferably an alkyl methacrylate with 2 to 18 carbon atoms in the alkyl group, and even more preferably an alkyl methacrylate with 4 to 14 carbon atoms in the alkyl group.

[0033] Furthermore, from the viewpoint of radical polymerization, the (M) component is preferably structured as shown in the following formula (2).

[0034] [ka]

[0035] (In the formula, X 1 ~X n-1 Each of these independently represents a hydrogen atom, a methyl group, or CH2OH, and Y 1 ~Y n Each of these independently bonds to the vinyl group of the vinyl radical polymerizable monomer (m2), which is the monomer of the macromonomer (M), X 1 ~X n-1This shows substituents other than the specified ones. Z represents a terminal group, and n represents an integer from 2 to 10000.

[0036] X 1 ~X n-1 and Y 1 ~Y n These are substituents that independently bond to the vinyl group of component (m2), for example, OR 11 , halogen atom, COR 12 COOR 13 , CN, CONR 14 R 15 NHCOR 16 , or R 17 Show, R 11 ~R 17 Each of these independently represents a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, etc.

[0037] The Z terminal group can be derived from a hydrogen atom or a radical polymerization initiator, similar to the terminal groups of polymers obtained by known radical polymerization.

[0038] Furthermore, in order to increase the solubility of (meth)acrylic graft copolymer A in the base oil and to enhance the friction reduction effect, the content of the constituent units derived from component (M) relative to the total mass of (meth)acrylic graft copolymer A is preferably 1 to 70% by mass, more preferably 2 to 60% by mass, and even more preferably 5 to 50% by mass.

[0039] In order to increase the solubility of the (meth)acrylic graft copolymer A in the base oil, it is preferable to contain 50% by mass or more of the constituent units derived from component (b) relative to the total mass of component (M), more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0040] In order to improve the solubility of the (meth)acrylic graft copolymer A in the base oil and to improve the friction reduction effect, the mass-average molecular weight (Mw) of the macromonomer (M), as measured by gel permeation chromatography (GPC), is preferably 1,000 to 50,000, more preferably 2,000 to 40,000, and even more preferably 3,000 to 30,000.

[0041] In order to improve the solubility of the (meth)acrylic graft copolymer A in the base oil and to improve the friction reduction effect, the number average molecular weight (Mn) of component (M) measured by gel permeation chromatography is preferably 500 to 30000, more preferably 1000 to 25000, and particularly preferably 2000 to 20000.

[0042] In order to improve the solubility of the (meth)acrylic graft copolymer A in the base oil and to improve the friction reduction effect, the molecular weight distribution (Mw / Mn) of the macromonomer (M) measured by gel permeation chromatography (GPC) is preferably 1.0 or more and 10 or less, more preferably 1.2 or more and 8 or less, and even more preferably 1.5 or more and 5 or less.

[0043] The aforementioned (M) component may be one that has been manufactured by a known method or one that is commercially available. Examples of methods for manufacturing the aforementioned M component include a method using a cobalt chain transfer agent (U.S. Patent No. 4,680,352), a method using an α-substituted unsaturated compound such as α-bromomethylstyrene as a chain transfer agent (International Publication No. 88 / 04304), a method of chemically bonding polymerizable groups (Japanese Patent Publication No. 60-133007 and U.S. Patent No. 5,147,952), and a method of thermal decomposition (Japanese Patent Publication No. 11-240,854).

[0044] The method using a cobalt chain transfer agent is preferred because it involves fewer manufacturing steps and utilizes a catalyst with a high chain transfer constant. Because cobalt chain transfer agents have a high chain transfer constant, macromonomers with controlled molecular weights can be obtained with only a small amount of addition.

[0045] Known cobalt complexes can be used as cobalt chain transfer agents. The amount of the cobalt chain transfer agent is preferably 0.00001 to 0.1 parts by mass, more preferably 0.00005 to 0.05 parts by mass, and particularly preferably 0.0001 to 0.02 parts by mass, per 100 parts by mass of the (m2) component.

[0046] Furthermore, the mass-average molecular weight (Mw) of the (meth)acrylic graft copolymer A contained in the lubricating oil additive of the present invention, as measured by GPC, is preferably 10,000 to 300,000, more preferably 20,000 to 250,000, and even more preferably 30,000 to 200,000, in order to increase the solubility of the (meth)acrylic graft copolymer A in the base oil and to increase the friction reduction effect.

[0047] Furthermore, the number-average molecular weight (Mn) of the (meth)acrylic graft copolymer A contained in the lubricating oil additive of the present invention, as measured by gel permeation chromatography (GPC), is preferably 5,000 to 100,000, more preferably 10,000 to 80,000, and even more preferably 15,000 to 50,000, in order to increase the solubility of the (meth)acrylic graft copolymer A in the base oil and to increase the friction reduction effect.

[0048] Furthermore, the molecular weight distribution (Mw / Mn) of the (meth)acrylic graft copolymer A contained in the lubricating oil additive of the present invention, as measured by gel permeation chromatography (GPC), is preferably 1.0 to 30, more preferably 2.0 to 25, and even more preferably 3.0 to 10, in order to increase the solubility of the (meth)acrylic graft copolymer A in the base oil and to enhance the friction reduction effect.

[0049] Next, an example of a method for producing the lubricating oil additive of the present invention is shown. The lubricating oil additive of the present invention can be produced by polymerizing a monomer mixture containing component (m1) and component (M) in a base oil using a known method. Polymerization can be carried out under known conditions, but it is preferable to use α-methylstyrene dimer as a chain transfer agent because it has a particularly excellent effect in suppressing heat generation during polymerization.

[0050] The aforementioned base oils are not particularly limited, but examples include API Group III base oils such as YUBASE3 manufactured by SK Lubricants, API Group III Plus base oils such as YUBASE4 manufactured by SK Lubricants, and API Group IV base oils such as polyalphaolefins.

[0051] Furthermore, the (M) component is preferably a macromonomer obtained by polymerizing a monomer mixture containing a vinyl-based radical polymerizable monomer in the base oil using a cobalt chain transfer agent. Because the cobalt chain transfer agent has a high chain transfer constant, a macromonomer with a controlled molecular weight can be obtained by adding only a small amount.

[0052] The lubricating oil additive containing (meth)acrylic graft copolymer A of the present invention can be used as a lubricating oil additive blended into engine oil, drive system 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 lubricant additives 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. The lubricating oil additive of the present invention is particularly preferable to be used as a friction reducer because it has excellent friction-reducing effects.

[0053] Examples of base oils for the aforementioned lubricating oils include mineral-based base oils refined from crude oil and chemically synthesized synthetic oils. Examples include API Group III base oils such as YUBASE3 manufactured by SK Lubricants, API Group III Plus base oils such as YUBASE4 manufactured by SK Lubricants, and API Group IV base oils such as polyalphaolefins.

[0054] The lubricating oil composition of the present invention is obtained by blending the lubricating oil additive of the present invention with a base oil. The lubricating oil composition of the present invention may contain other additives besides the lubricating oil additive of the present invention. Examples of other additives include antioxidants, viscosity index improvers, pour point depressants, detergent dispersants, corrosion inhibitors, rust inhibitors, defoaming agents, emulsifiers, antifungal agents, and anti-emulsifiers. In addition, other friction reducing agents may include oiliness improvers 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 organic molybdenum compounds. Furthermore, the lubricating oil composition of the present invention may also be a grease containing a thickener. Examples of thickeners include soap-based (lithium soap, calcium soap, sodium soap, aluminum soap, etc.), inorganic (bentonite, silica gel, etc.), and organic (polyurea, polyurethane, etc.).

[0055] The content of the lubricating oil additive of the present invention in the lubricating oil composition is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and even more preferably 0.1 to 20% by mass, based on 100% by mass of the lubricating oil composition. A content of 0.01% by mass or more of the lubricating oil additive can enhance the friction reduction effect. A content of 30% by mass or less can lower the viscosity of the lubricating oil composition. [Examples]

[0056] The present invention will be described in more detail below with reference to examples and comparative examples. In the examples, "parts" refers to "parts by mass." In Tables 1 to 4, the content of constituent units derived from each monomer is shown in mass percent. The content of each constituent unit was calculated from the mass of the monomer relative to the total mass of the monomers used in the polymerization reaction. The evaluation was performed by the following method.

[0057] <Molecular weight of macromonomer (M)> Measurements were performed using gel permeation chromatography (GPC) (HLC-8320, manufactured by Tosoh Corporation). After preparing a 0.2% by mass solution of macromonomer (M) in tetrahydrofuran, 10 μl of the solution was injected into an apparatus equipped with Tosoh Corporation columns (TSKgel SuperHZM-M (inner diameter 4.6 mm, length 15 cm), HZM-M (inner diameter 4.6 mm, length 15 cm), HZ-2000 (inner diameter 4.6 mm, length 15 cm), TSKguardcolumn SuperHZ-L (inner diameter 4.6 mm, length 3.5 cm)). Measurements were performed under the following conditions: flow rate: 0.35 ml / min, eluent: tetrahydrofuran (stabilizer BHT), column temperature: 40°C, and Mw, Mn, and Mw / Mn were calculated in terms of standard polystyrene.

[0058] <Molecular weight of (meth)acrylic copolymer> The measurements were performed using gel permeation chromatography (GPC) (HLC-8320, manufactured by Tosoh Corporation). After preparing a 0.2% by mass solution of the (meth)acrylic copolymer obtained in the examples using tetrahydrofuran, 10 μl of the above solution was injected into an apparatus equipped with two Tosoh columns (TSKgelSuperHZM-H (inner diameter 6.0 mm, length 15 cm) and a TSKguardcolumn SuperHZ-H (inner diameter 4.6 mm, length 3.5 cm)). Measurements were performed under the conditions of a flow rate of 0.5 ml / min, eluent: tetrahydrofuran (stabilizer BHT), and column temperature: 40°C. The mass-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were calculated in terms of standard polystyrene.

[0059] <Coefficient of friction at 40℃> A YUBASE4 solution containing 2% by mass of the obtained (meth)acrylic copolymer was prepared, and the coefficient of friction at 40°C was measured using an SRV5 tester (manufactured by Optimol Instruments Pruftechnik GmbH). The measurement conditions were as follows, and the coefficient of friction was evaluated 30 minutes after the start of measurement. • Test method: Ball on disc (Ball diameter: 10mm, Ball and disc material: SUJ2) • Test mode: Reciprocating (50Hz, 1mm stroke) • Load: 200N

[0060] [Manufacturing Example 1] (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 (manufactured by Wako Pure Chemical Industries, Ltd., Wako Special Grade), 3.86 g (16.1 mmol) of diphenylglyoxime (manufactured by Tokyo Chemical Industry Co., 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. The resulting solution was filtered, the solid was washed with diethyl ether, and dried at 20°C under 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.

[0061] [Manufacturing Example 2] (Synthesis of macromonomer M1) In a reaction vessel equipped with a stirrer, condenser, and thermometer, 58 parts of YUBASE4, 96 parts of Acryester SL (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester SL, a mixture of alkyl methacrylate with 12 carbon atoms in the alkyl group and alkyl methacrylate with 13 carbon atoms in the alkyl group), 2 parts of 2,2,2-trifluoroethyl methacrylate (manufactured by Mitsubishi Chemical Corporation, trade name: 3FE), 2 parts of methyl methacrylate (MMA), and 0.005 parts of the Co complex prepared in Production Example 1 were added. The liquid temperature was raised to 40°C, and dissolved oxygen was removed by bubbling nitrogen over the mixture for 2 hours while stirring. A mixture of YUBASE4 (2 parts) and the polymerization initiator t-butyl peroxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 26) (0.1 parts) was added, and the temperature was raised to 90°C. After stirring for 2.5 hours, a mixture of YUBASE4 (10 parts) and 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perocta O) (0.7 parts) was added dropwise over 1 hour. After the dropwise addition, the temperature was raised to 95°C and held for 2 hours. Then, 20 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M1. The GPC results of the obtained macromonomer M1 are shown in Table 1.

[0062] [Manufacturing Example 3] (Synthesis of macromonomer M2) In a reaction vessel equipped with a stirrer, condenser, and thermometer, 58 parts of YUBASE4, 88 parts of acrylic ester SL, 10 parts of 3FE, 2 parts of MMA, and 0.005 parts of the Co complex prepared in Production Example 1 were added. The temperature was raised to 40°C, and dissolved oxygen was removed by bubbling nitrogen over the mixture for 2 hours while stirring. A mixture of YUBASE4 (2 parts) and Luperox 26 (0.1 parts) was added, and the temperature was raised to 90°C. After stirring for 2.5 hours, a mixture of YUBASE4 (10 parts) and Perocta O (0.7 parts) was added dropwise over 1 hour. After the dropwise addition, the temperature was raised to 95°C and held for 2 hours. Then, 20 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M2. The GPC results of the obtained macromonomer M2 are shown in Table 1.

[0063] [Manufacturing Example 4] (Synthesis of macromonomer M3) In a reaction vessel equipped with a stirrer, condenser, and thermometer, 58 parts of YUBASE4, 73 parts of acrylic ester SL, 25 parts of 3FE, 2 parts of MMA, and 0.005 parts of the Co complex prepared in Production Example 1 were added. The temperature was raised to 40°C, and dissolved oxygen was removed by bubbling nitrogen over the mixture for 2 hours while stirring. A mixture of YUBASE4 (2 parts) and Luperox 26 (0.1 parts) was added, and the temperature was raised to 90°C. After stirring for 2.5 hours, a mixture of YUBASE4 (10 parts) and Perocta O (0.7 parts) was added dropwise over 1 hour. After the dropwise addition, the temperature was raised to 95°C and held for 2 hours. Then, 20 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M3. The GPC results of the obtained macromonomer M3 are shown in Table 1.

[0064] [Manufacturing Example 5] (Synthesis of macromonomer M4) In a reaction vessel equipped with a stirrer, condenser, and thermometer, 58 parts of YUBASE4, 96 parts of Acryester SL, 2 parts of 1H,1H,2H,2H-tridecafluorooctyl (meth)acrylate methacrylic acid (manufactured by Daikin Industries, Ltd., trade name: C6SFMA), 2 parts of MMA, and 0.005 parts of the Co complex prepared in Production Example 1 were added. The temperature was raised to 40°C, and dissolved oxygen was removed by bubbling nitrogen over the mixture for 2 hours while stirring. A mixture of YUBASE4 (2 parts) and Luperox 26 (0.1 parts) was added, the temperature was raised to 90°C, and after stirring for 2.5 hours, a mixture of YUBASE4 (10 parts) and Perocta O (0.7 parts) was added dropwise over 1 hour. After dropwise addition, the temperature was raised to 95°C and maintained for 2 hours. Then, 20 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M4. The GPC results of the obtained macromonomer M4 are shown in Table 1.

[0065] [Manufacturing Example 6] (Synthesis of macromonomer M5) In a reaction vessel equipped with a stirrer, condenser, and thermometer, 58 parts of YUBASE4, 98 parts of acrylic ester SL, 2 parts of MMA, and 0.005 parts of the Co complex prepared in Production Example 1 were added. The temperature was raised to 40°C, and dissolved oxygen was removed by bubbling nitrogen over the mixture for 2 hours while stirring. A mixture of YUBASE4 (2 parts) and Luperox 26 (0.1 parts) was added, and the temperature was raised to 90°C. After stirring for 2.5 hours, a mixture of YUBASE4 (10 parts) and Luperox 26 (0.7 parts) was added dropwise over 1 hour. After the dropwise addition, the temperature was raised to 105°C and held for 1.5 hours. Then, 20 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M5. The GPC results of the obtained macromonomer M5 are shown in Table 1.

[0066] [Manufacturing Example 7] (Synthesis of macromonomer M6) In a reaction vessel equipped with a stirrer, condenser, and thermometer, 58 parts of YUBASE4, 98 parts of acrylic ester SL, 2 parts of methyl methacrylate (MMA), and 0.005 parts of the Co complex prepared in Production Example 1 were added. The temperature was raised to 40°C, and dissolved oxygen was removed by bubbling nitrogen over the mixture for 2 hours while stirring. A mixture of 2 parts of YUBASE4 and 0.1 parts of t-amyl peroxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi, trade name: Luperox 575), a polymerization initiator, was added, and the temperature was raised to 90°C. After stirring for 2.5 hours, a mixture of 10 parts of YUBASE4 and 0.7 parts of Luperox 26 was added dropwise over 1 hour. After dropwise addition, the temperature was raised to 105°C and maintained for 1.5 hours. Then, 20 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M6. The GPC results of the obtained macromonomer M6 are shown in Table 1.

[0067] <Example 1> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of a YUBASE4 solution of macromonomer M1 (a macromonomer containing 2% by mass of constituent units derived from 2,2,2-trifluoroethyl methacrylate as component (a)) obtained in Production Example 2 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 YUBASE4 (25 parts), n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: nBA) (56 parts), lauryl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., trade name: LA) (19 parts), t-amyl peroxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 575) (0.4 parts) as a polymerization initiator, and α-methylstyrene dimer (manufactured by NOF Corporation, trade name: Nofmer MSD) (0.9 parts) as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. The temperature was raised to 95°C and held for 2 hours, after which YUBASE4 (58.1 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 2 shows the GPC results for the obtained (meth)acrylic copolymers and the evaluation results for friction reducers for lubricating oils. The monomer composition in Table 2 contains 25% by mass of macromonomer M1, and the monomers constituting macromonomer M1 are 0.5% by mass of 3FE, 24% by mass of SLMA, and 0.5% by mass of MMA, indicating that constituent units derived from 3FE are present in the side chains of the graft copolymer.

[0068] <Example 2> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of a YUBASE4 solution of macromonomer M2 (a macromonomer containing 10% by mass of constituent units derived from 2,2,2-trifluoroethyl methacrylate as component (a)) obtained in Production Example 3 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 YUBASE4 (25 parts), nBA (56 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding it for 2 hours, 58.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 2 shows the GPC results for the obtained (meth)acrylic copolymers and the evaluation results for friction reducers for lubricating oils. The monomer composition in Table 2 contains 25% by mass of macromonomer M2, and the monomers constituting macromonomer M2 are 2.5% by mass of 3FE, 22% by mass of SLMA, and 0.5% by mass of MMA, indicating that constituent units derived from 3FE are present in the side chains of the graft copolymer.

[0069] <Example 3> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 95.1 parts of a YUBASE4 solution of macromonomer M2 (a macromonomer containing 10% by mass of constituent units derived from 2,2,2-trifluoroethyl methacrylate as component (a)) obtained in Production Example 3 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 YUBASE4 (25 parts), nBA (50 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding it for 2 hours, 35.5 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 2 shows the GPC results for the obtained (meth)acrylic copolymers and the evaluation results for friction reducers for lubricating oils. The monomer composition in Table 2 contains 50% by mass of macromonomer M2, and the monomers constituting macromonomer M2 are 5% by mass of 3FE, 44% by mass of SLMA, and 1% by mass of MMA, indicating that constituent units derived from 3FE are present in the side chains of the graft copolymer.

[0070] <Example 4> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of a YUBASE4 solution of macromonomer M3 (a macromonomer containing 25% by mass of constituent units derived from 2,2,2-trifluoroethyl methacrylate as component (a)) obtained in Production Example 4 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 YUBASE4 (25 parts), n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: nBA) (56 parts), lauryl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., trade name: LA) (19 parts), t-amyl peroxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 575) (0.4 parts) as a polymerization initiator, and α-methylstyrene dimer (manufactured by NOF Corporation, trade name: Nofmer MSD) (0.9 parts) as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. The temperature was raised to 95°C and held for 2 hours, after which YUBASE4 (58.1 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 2 shows the GPC results for the obtained (meth)acrylic copolymers and the evaluation results for friction reducers for lubricating oils. The monomer composition in Table 2 includes 25% by mass of macromonomer M3, and the monomers constituting macromonomer M1 are 6.25% by mass of 3FE, 18.25% by mass of SLMA, and 0.5% by mass of MMA, indicating that constituent units derived from 3FE are present in the side chains of the graft copolymer.

[0071] <Example 5> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 95.1 parts of a YUBASE4 solution of macromonomer M3 (a macromonomer containing 25% by mass of constituent units derived from 2,2,2-trifluoroethyl methacrylate as component (a)) obtained in Production Example 4 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 YUBASE4 (25 parts), nBA (50 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding it for 2 hours, 35.5 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 2 shows the GPC results for the obtained (meth)acrylic copolymers and the evaluation results for friction reducers for lubricating oils. The monomer composition in Table 2 contains 50% by mass of macromonomer M3, and the monomers constituting macromonomer M3 are 12.5% ​​by mass of 3FE, 36.5% by mass of SLMA, and 1% by mass of MMA, indicating that constituent units derived from 3FE are present in the side chains of the graft copolymer.

[0072] <Example 6> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of a YUBASE4 solution of macromonomer M4 (a macromonomer containing 2% by mass of 1H,1H,2H,2H-tridecafluorooctyl (meth)acrylate as component (a)) obtained in Production Example 5 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 YUBASE4 (25 parts), nBA (56 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding it for 2 hours, 58.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 2 shows the GPC results for the obtained (meth)acrylic copolymers and the evaluation results for friction reducers for lubricating oils. The monomer composition in Table 2 contains 25% by mass of macromonomer M4, and the monomers constituting macromonomer M4 are 0.5% by mass of C6SFMA, 24% by mass of SLMA, and 0.5% by mass of MMA, indicating that the constituent units derived from C6SFMA are present in the side chains of the graft copolymer.

[0073] <Example 7> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M5 obtained in Production Example 6 were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the liquid was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), 3FE (0.5 parts), nBA (55.5 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding for 2 hours, YUBASE4 (58.1 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 3 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 3 indicates that the polymer contains 25% by mass of macromonomer M5, and that the monomers constituting macromonomer M5 are 24.5% by mass of SLMA and 0.5% by mass of MMA, and that the constituent units derived from 3FE are present in the main chain of the graft copolymer.

[0074] <Example 8> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M5 obtained in Production Example 6 were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the liquid was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), 3FE (2.5 parts), nBA (53.5 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding for 2 hours, YUBASE4 (58.1 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 3 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 3 indicates that the polymer contains 25% by mass of macromonomer M5, and that the monomers constituting macromonomer M5 are 24.5% by mass of SLMA and 0.5% by mass of MMA, and that the constituent units derived from 3FE are present in the main chain of the graft copolymer.

[0075] <Example 9> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M5 obtained in Production Example 5 were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the liquid was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), 3FE (5 parts), nBA (51 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding for 2 hours, YUBASE4 (58.1 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 3 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 3 indicates that the polymer contains 25% by mass of macromonomer M5, and that the monomers constituting macromonomer M5 are 24.5% by mass of SLMA and 0.5% by mass of MMA, and that the constituent units derived from 3FE are present in the main chain of the graft copolymer.

[0076] <Example 10> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M6 obtained in Production Example 7 were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the liquid was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), 3FE (2.5 parts), nBA (53.5 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding for 2 hours, YUBASE4 (58.1 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 3 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 3 indicates that the polymer contains 25% by mass of macromonomer M6, and that the monomers constituting macromonomer M6 are 24.5% by mass of SLMA and 0.5% by mass of MMA, and that constituent units derived from 3FE are present in the main chain of the graft copolymer.

[0077] <Example 11> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of a YUBASE4 solution of macromonomer M2 (a macromonomer containing 10% by mass of constituent units derived from 2,2,2-trifluoroethyl methacrylate as component (a)) obtained in Production Example 3 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 YUBASE4 (25 parts), nBA (56 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.7 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding it for 2 hours, 58.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 3 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 3 contains 25% by mass of macromonomer M2, and the monomers constituting macromonomer M2 are 2.5% by mass of 3FE, 22% by mass of SLMA, and 0.5% by mass of MMA, indicating that constituent units derived from 3FE are present in the side chains of the graft copolymer.

[0078] <Example 12> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of a YUBASE4 solution of macromonomer M2 (a macromonomer containing 10% by mass of constituent units derived from 2,2,2-trifluoroethyl methacrylate as component (a)) obtained in Production Example 3 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 YUBASE4 (25 parts), nBA (56 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.5 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding it for 2 hours, 58.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 3 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 3 contains 25% by mass of macromonomer M2, and the monomers constituting macromonomer M2 are 2.5% by mass of 3FE, 22% by mass of SLMA, and 0.5% by mass of MMA, indicating that constituent units derived from 3FE are present in the side chains of the graft copolymer.

[0079] <Example 13> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of a YUBASE4 solution of macromonomer M2 (a macromonomer containing 10% by mass of constituent units derived from 2,2,2-trifluoroethyl methacrylate as component (a)) obtained in Production Example 3 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 YUBASE4 (25 parts), nBA (56 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.3 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding it for 2 hours, 58.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 3 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 3 contains 25% by mass of macromonomer M2, and the monomers constituting macromonomer M2 are 2.5% by mass of 3FE, 22% by mass of SLMA, and 0.5% by mass of MMA, indicating that constituent units derived from 3FE are present in the side chains of the graft copolymer.

[0080] <Example 14> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M5 obtained in Production Example 5 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 YUBASE4 (25 parts), 3FE (5 parts), nBA (51 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.5 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding for 2 hours, YUBASE4 (58.1 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 3 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 3 indicates that the polymer contains 25% by mass of macromonomer M5, and that the monomers constituting macromonomer M5 are 24.5% by mass of SLMA and 0.5% by mass of MMA, and that the constituent units derived from 3FE are present in the main chain of the graft copolymer.

[0081] <Example 15> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 30 parts of YUBASE4 and 47.6 parts of a YUBASE4 solution of macromonomer M2 (a macromonomer containing 10% by mass of constituent units derived from 2,2,2-trifluoroethyl methacrylate as component (a)) obtained in Production Example 3 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 YUBASE4 (25 parts), 3FE (2.5 parts), nBA (53.5 parts), LA (19 parts), Luperox 575 (0.4 parts), and Nofmer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Perocta O (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and holding it for 2 hours, 58.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 3 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 3 indicates that the polymer contains 25% by mass of macromonomer M2, and that the monomers constituting macromonomer M2 are 2.5% by mass of 3FE, 22% by mass of SLMA, and 0.5% by mass of MMA. This means that 2.5% by mass of the constituent units derived from 3FE are present in the side chains of the graft copolymer, and 2.5% by mass are present in the main chain.

[0082] <Comparative Example 1> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 50 parts of YUBASE4, 47.6 parts of a YUBASE4 solution of macromonomer M5 obtained in Production Example 6, 56 parts of nBA, 19 parts of LA, 0.03 parts of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O) as a polymerization initiator, and 0.4 parts of Nofmer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the mixture was raised to 85°C and held for 3.5 hours, after which a mixture of YUBASE4 (42 parts) and Perbutyl O (0.015 parts) was added dropwise over 2 hours. Furthermore, after holding at 85°C for 1 hour, a mixture of YUBASE4 (30 parts) and Perocta O (0.5 parts) was added dropwise over 1 hour. The temperature was then raised to 110°C and held for 1 hour. After that, 41.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 4 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil. The monomer composition in Table 4 indicates that the product contains 25% by mass of macromonomer M5, and that the monomers constituting macromonomer M5 are 24.5% by mass of SLMA and 0.5% by mass of MMA.

[0083] <Comparative Example 2> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 72.6 parts of YUBASE4, 0.5 parts of 3FE, 45 parts of nBA, 30 parts of LA, 24.5 parts of acrylic SL, 0.03 parts of perbutyl O, and 0.15 parts of Nofmer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature was raised to 85°C and held for 3.5 hours, after which a mixture of YUBASE4 (42 parts) and perbutyl O (0.015 parts) was added dropwise over 2 hours. After further holding at 85°C for 1 hour, a mixture of YUBASE4 (60 parts) and perocta O (0.5 parts) was added dropwise over 1 hour. Then the temperature was raised to 95°C and held for 2 hours, after which 11.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 4 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil.

[0084] <Comparative Example 3> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 72.6 parts of YUBASE4, 0.5 parts of C6SFMA, 45 parts of nBA, 30 parts of LA, 24.5 parts of acrylic SL, 0.03 parts of perbutyl O, and 0.15 parts of Nofmer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature was raised to 85°C and held for 3.5 hours, after which a mixture of YUBASE4 (42 parts) and perbutyl O (0.015 parts) was added dropwise over 2 hours. After further holding at 85°C for 1 hour, a mixture of YUBASE4 (60 parts) and perocta O (0.5 parts) was added dropwise over 1 hour. The temperature was then raised to 95°C and held for 2 hours, after which 11.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 4 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil.

[0085] <Comparative Example 4> In a reaction vessel equipped with a stirrer, condenser, and thermometer, 72.6 parts of YUBASE4, 10 parts of C6SFMA, 35 parts of nBA, 30 parts of LA, 25 parts of acrylic ester SL, 0.03 parts of perbutyl O, and 0.15 parts of nofmer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature was raised to 85°C and held for 3.5 hours, after which a mixture of YUBASE4 (42 parts) and perbutyl O (0.015 parts) was added dropwise over 2 hours. After further holding at 85°C for 1 hour, a mixture of YUBASE4 (60 parts) and perocta O (0.5 parts) was added dropwise over 1 hour. Then the temperature was raised to 95°C and held for 2 hours, after which 11.1 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic copolymer. Table 4 shows the GPC results for the obtained (meth)acrylic copolymer and the evaluation results for the friction reducer for lubricating oil.

[0086] As shown in the results in Table 4, Comparative Example 1 is a graft copolymer, but because it does not contain constituent units derived from fluorine-containing (meth)acrylate (a), the coefficient of friction was high. Also, Comparative Examples 2-4 are not graft copolymers, and therefore the coefficient of friction was high.

[0087] [Table 1]

[0088] [Table 2]

[0089] [Table 3]

[0090] [Table 4]

[0091] The abbreviations in Tables 1-4 are as follows: • 3FE: 2,2,2-trifluoroethyl methacrylate (manufactured by Mitsubishi Chemical Corporation, product name: 3FE) • C6SFMA: 1H,1H,2H,2H-Tridecafluorooctyl (meth)acrylate (manufactured by Daikin Industries, Ltd., product name: C6SFMA) • MMA: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, product name: Acryester M) • 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 (manufactured by Mitsubishi Chemical Corporation, product name: Acryester SL) • M1: Macromonomer synthesized in Manufacturing Example 2 • M2: Macromonomer synthesized in Manufacturing Example 3 • M3: Macromonomer synthesized in Manufacturing Example 4 • M4: Macromonomer synthesized in Manufacturing Example 5 • M5: Macromonomer synthesized in Manufacturing Example 6 • M6: Macromonomer synthesized in Manufacturing Example 7 nBA: n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation, product name: butyl acrylate) • LA: Lauryl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name: LA)

Claims

1. A lubricating oil additive containing a (meth)acrylic graft copolymer A that includes a constituent unit derived from (meth)acrylate (a) having a fluorine atom, The (meth)acrylic graft copolymer A comprises a constituent unit derived from a vinyl radical polymerizable monomer (m1) and a constituent unit derived from a macromonomer (M). A lubricating oil additive wherein the macromonomer (M) comprises a constituent unit derived from a vinyl-based radical polymerizable monomer (m2), and the vinyl-based radical polymerizable monomer (m2) comprises a constituent unit derived from an alkyl (meth)acrylate (b) having a linear or branched alkyl group.

2. The lubricating oil additive according to claim 1, wherein the (meth)acrylate (a) having a fluorine atom includes a (meth)acrylate represented by the following formula (1). 【Chemistry 1】 (In the formula, R １ is a hydrogen atom or a methyl group, -R ２ - is, - (CH ２ ) ｐ - or -CH ２ CH(OH)CH ２ It is a group represented by -, where p is 0 to 4, and R ３ (This represents a linear or branched alkyl group having 1 to 10 carbon atoms, in which one or more hydrogen atoms are replaced by fluorine atoms.)

3. The lubricating oil additive according to claim 1, wherein the alkyl (meth)acrylate (b) has 1 to 20 carbon atoms in the alkyl group.

4. The lubricating oil additive according to claim 1, wherein the macromonomer (M) has the structure of the following formula (2). 【Chemistry 2】 (In the formula, X １ to X ｎ－１ each independently represents a hydrogen atom, a methyl group or CH ２ OH, Y １ to Y ｎ each independently represents a substituent other than X １ to X ｎ－１ bonded to the vinyl group of the vinyl radical-polymerizable monomer (m2) which is a monomer of the macromonomer (M). Z represents a terminal group, and n represents an integer of 2 to 10,000.)

5. The lubricating oil additive according to claim 1, wherein the mass-average molecular weight of the (meth)acrylic graft copolymer A is 5,000 to 200,000.

6. The lubricating oil additive according to claim 1, which is a friction reducing agent for lubricating oil.

7. A lubricating oil composition comprising the lubricating oil additive according to any one of claims 1 to 6.

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